i2c: at91: slave mode support

In order to implement slave mode support for the at91 hardware we have to segregate all master mode specific function parts from the general parts. The upcoming slave mode patch will call its sepcific probe resp. init function instead of the master mode functions after the shared general code has been executed.

This concept has been influenced by the i2c-designware driver.

Signed-off-by Juergen Fitschen <[email protected]>

---
 drivers/i2c/busses/i2c-at91.c | 90 ++++++++++++++++++++++++++-----------------
 1 file changed, 55 insertions(+), 35 deletions(-)

drivers/i2c/busses/i2c-at91.c +55 -35

index bfd1fdf..73b6582 100644
@@ -174,10 +174,8 @@ static void at91_twi_irq_restore(struct at91_twi_dev *dev)
 	at91_twi_write(dev, AT91_TWI_IER, dev->imr);
 }
 
-static void at91_init_twi_bus(struct at91_twi_dev *dev)
+static void at91_init_twi_bus_master(struct at91_twi_dev *dev)
 {
-	at91_disable_twi_interrupts(dev);
-	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SWRST);
 	/* FIFO should be enabled immediately after the software reset */
 	if (dev->fifo_size)
 		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_FIFOEN);

@@ -186,6 +184,14 @@ static void at91_init_twi_bus(struct at91_twi_dev *dev)
 	at91_twi_write(dev, AT91_TWI_CWGR, dev->twi_cwgr_reg);
 }
 
+static void at91_init_twi_bus(struct at91_twi_dev *dev)
+{
+	at91_disable_twi_interrupts(dev);
+	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SWRST);
+
+	at91_init_twi_bus_master(dev);
+}
+
 /*
  * Calculate symmetric clock as stated in datasheet:
  * twi_clk = F_MAIN / (2 * (cdiv * (1 << ckdiv) + offset))

@@ -1038,18 +1044,56 @@ static struct at91_twi_pdata *at91_twi_get_driver_data(
 	return (struct at91_twi_pdata *) platform_get_device_id(pdev)->driver_data;
 }
 
+static int at91_twi_probe_master(struct platform_device *pdev,
+				 u32 phy_addr, struct at91_twi_dev *dev)
+{
+	int rc;
+	u32 bus_clk_rate;
+
+	init_completion(&dev->cmd_complete);
+
+	rc = devm_request_irq(&pdev->dev, dev->irq, atmel_twi_interrupt, 0,
+			      dev_name(dev->dev), dev);
+	if (rc) {
+		dev_err(dev->dev, "Cannot get irq %d: %d\n", dev->irq, rc);
+		return rc;
+	}
+
+	if (dev->dev->of_node) {
+		rc = at91_twi_configure_dma(dev, phy_addr);
+		if (rc == -EPROBE_DEFER)
+			return rc;
+	}
+
+	if (!of_property_read_u32(pdev->dev.of_node, "atmel,fifo-size",
+				  &dev->fifo_size)) {
+		dev_info(dev->dev, "Using FIFO (%u data)\n", dev->fifo_size);
+	}
+
+	rc = of_property_read_u32(dev->dev->of_node, "clock-frequency",
+				  &bus_clk_rate);
+	if (rc)
+		bus_clk_rate = DEFAULT_TWI_CLK_HZ;
+
+	at91_calc_twi_clock(dev, bus_clk_rate);
+
+	dev->adapter.algo = &at91_twi_algorithm;
+	dev->adapter.quirks = &at91_twi_quirks;
+
+	return 0;
+}
+
 static int at91_twi_probe(struct platform_device *pdev)
 {
 	struct at91_twi_dev *dev;
 	struct resource *mem;
 	int rc;
 	u32 phy_addr;
-	u32 bus_clk_rate;
 
 	dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
 	if (!dev)
 		return -ENOMEM;
-	init_completion(&dev->cmd_complete);
+
 	dev->dev = &pdev->dev;
 
 	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);

@@ -1069,13 +1113,6 @@ static int at91_twi_probe(struct platform_device *pdev)
 	if (dev->irq < 0)
 		return dev->irq;
 
-	rc = devm_request_irq(&pdev->dev, dev->irq, atmel_twi_interrupt, 0,
-			 dev_name(dev->dev), dev);
-	if (rc) {
-		dev_err(dev->dev, "Cannot get irq %d: %d\n", dev->irq, rc);
-		return rc;
-	}
-
 	platform_set_drvdata(pdev, dev);
 
 	dev->clk = devm_clk_get(dev->dev, NULL);

@@ -1087,38 +1124,21 @@ static int at91_twi_probe(struct platform_device *pdev)
 	if (rc)
 		return rc;
 
-	if (dev->dev->of_node) {
-		rc = at91_twi_configure_dma(dev, phy_addr);
-		if (rc == -EPROBE_DEFER) {
-			clk_disable_unprepare(dev->clk);
-			return rc;
-		}
-	}
-
-	if (!of_property_read_u32(pdev->dev.of_node, "atmel,fifo-size",
-				  &dev->fifo_size)) {
-		dev_info(dev->dev, "Using FIFO (%u data)\n", dev->fifo_size);
-	}
-
-	rc = of_property_read_u32(dev->dev->of_node, "clock-frequency",
-			&bus_clk_rate);
-	if (rc)
-		bus_clk_rate = DEFAULT_TWI_CLK_HZ;
-
-	at91_calc_twi_clock(dev, bus_clk_rate);
-	at91_init_twi_bus(dev);
-
 	snprintf(dev->adapter.name, sizeof(dev->adapter.name), "AT91");
 	i2c_set_adapdata(&dev->adapter, dev);
 	dev->adapter.owner = THIS_MODULE;
 	dev->adapter.class = I2C_CLASS_DEPRECATED;
-	dev->adapter.algo = &at91_twi_algorithm;
-	dev->adapter.quirks = &at91_twi_quirks;
 	dev->adapter.dev.parent = dev->dev;
 	dev->adapter.nr = pdev->id;
 	dev->adapter.timeout = AT91_I2C_TIMEOUT;
 	dev->adapter.dev.of_node = pdev->dev.of_node;
 
+	rc = at91_twi_probe_master(pdev, phy_addr, dev);
+	if (rc)
+		return rc;
+
+	at91_init_twi_bus(dev);
+
 	pm_runtime_set_autosuspend_delay(dev->dev, AUTOSUSPEND_TIMEOUT);
 	pm_runtime_use_autosuspend(dev->dev);
 	pm_runtime_set_active(dev->dev);

Signature · 1 line

2.7.4

The single file i2c-at91.c has been split into core code (i2c-at91-core.c) and master mode specific code (i2c-at91-master.c). This should enhance maintainability and reduce ifdeffery for slave mode related code.

The code itself hasn't been touched. Shared functions only had to be made non-static. Furthermore, includes have been cleaned up.

Signed-off-by Juergen Fitschen <[email protected]>

---
 MAINTAINERS                          |    3 +-
 drivers/i2c/busses/Makefile          |    1 +
 drivers/i2c/busses/i2c-at91-core.c   |  373 ++++++++++
 drivers/i2c/busses/i2c-at91-master.c |  804 ++++++++++++++++++++++
 drivers/i2c/busses/i2c-at91.c        | 1263 ----------------------------------
 drivers/i2c/busses/i2c-at91.h        |  151 ++++
 6 files changed, 1331 insertions(+), 1264 deletions(-)
 create mode 100644 drivers/i2c/busses/i2c-at91-core.c
 create mode 100644 drivers/i2c/busses/i2c-at91-master.c
 delete mode 100644 drivers/i2c/busses/i2c-at91.c
 create mode 100644 drivers/i2c/busses/i2c-at91.h

MAINTAINERS +2 -1

index d85c089..b697db8 100644
@@ -2341,7 +2341,8 @@ ATMEL I2C DRIVER
 M:	Ludovic Desroches <[email protected]>
 L:	[email protected]
 S:	Supported
-F:	drivers/i2c/busses/i2c-at91.c
+F:	drivers/i2c/busses/i2c-at91.h
+F:	drivers/i2c/busses/i2c-at91-*.c
 
 ATMEL ISI DRIVER
 M:	Ludovic Desroches <[email protected]>

drivers/i2c/busses/Makefile +1 -0

index 47f3ac9..2a79c3d 100644
@@ -33,6 +33,7 @@ obj-$(CONFIG_I2C_POWERMAC)	+= i2c-powermac.o
 obj-$(CONFIG_I2C_ALTERA)	+= i2c-altera.o
 obj-$(CONFIG_I2C_ASPEED)	+= i2c-aspeed.o
 obj-$(CONFIG_I2C_AT91)		+= i2c-at91.o
+i2c-at91-objs			:= i2c-at91-core.o i2c-at91-master.o
 obj-$(CONFIG_I2C_AU1550)	+= i2c-au1550.o
 obj-$(CONFIG_I2C_AXXIA)		+= i2c-axxia.o
 obj-$(CONFIG_I2C_BCM2835)	+= i2c-bcm2835.o

drivers/i2c/busses/i2c-at91-core.c new file +373 -0

new file mode 100644
index 0000000..4fed72d
@@ -0,0 +1,373 @@
+/*
+ *  i2c Support for Atmel's AT91 Two-Wire Interface (TWI)
+ *
+ *  Copyright (C) 2011 Weinmann Medical GmbH
+ *  Author: Nikolaus Voss <[email protected]>
+ *
+ *  Evolved from original work by:
+ *  Copyright (C) 2004 Rick Bronson
+ *  Converted to 2.6 by Andrew Victor <[email protected]>
+ *
+ *  Borrowed heavily from original work by:
+ *  Copyright (C) 2000 Philip Edelbrock <[email protected]>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/pinctrl/consumer.h>
+
+#include "i2c-at91.h"
+
+unsigned at91_twi_read(struct at91_twi_dev *dev, unsigned reg)
+{
+	return readl_relaxed(dev->base + reg);
+}
+
+void at91_twi_write(struct at91_twi_dev *dev, unsigned reg, unsigned val)
+{
+	writel_relaxed(val, dev->base + reg);
+}
+
+void at91_disable_twi_interrupts(struct at91_twi_dev *dev)
+{
+	at91_twi_write(dev, AT91_TWI_IDR, AT91_TWI_INT_MASK);
+}
+
+void at91_twi_irq_save(struct at91_twi_dev *dev)
+{
+	dev->imr = at91_twi_read(dev, AT91_TWI_IMR) & AT91_TWI_INT_MASK;
+	at91_disable_twi_interrupts(dev);
+}
+
+void at91_twi_irq_restore(struct at91_twi_dev *dev)
+{
+	at91_twi_write(dev, AT91_TWI_IER, dev->imr);
+}
+
+void at91_init_twi_bus(struct at91_twi_dev *dev)
+{
+	at91_disable_twi_interrupts(dev);
+	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SWRST);
+
+	at91_init_twi_bus_master(dev);
+}
+
+static struct at91_twi_pdata at91rm9200_config = {
+	.clk_max_div = 5,
+	.clk_offset = 3,
+	.has_unre_flag = true,
+	.has_alt_cmd = false,
+	.has_hold_field = false,
+};
+
+static struct at91_twi_pdata at91sam9261_config = {
+	.clk_max_div = 5,
+	.clk_offset = 4,
+	.has_unre_flag = false,
+	.has_alt_cmd = false,
+	.has_hold_field = false,
+};
+
+static struct at91_twi_pdata at91sam9260_config = {
+	.clk_max_div = 7,
+	.clk_offset = 4,
+	.has_unre_flag = false,
+	.has_alt_cmd = false,
+	.has_hold_field = false,
+};
+
+static struct at91_twi_pdata at91sam9g20_config = {
+	.clk_max_div = 7,
+	.clk_offset = 4,
+	.has_unre_flag = false,
+	.has_alt_cmd = false,
+	.has_hold_field = false,
+};
+
+static struct at91_twi_pdata at91sam9g10_config = {
+	.clk_max_div = 7,
+	.clk_offset = 4,
+	.has_unre_flag = false,
+	.has_alt_cmd = false,
+	.has_hold_field = false,
+};
+
+static const struct platform_device_id at91_twi_devtypes[] = {
+	{
+		.name = "i2c-at91rm9200",
+		.driver_data = (unsigned long) &at91rm9200_config,
+	}, {
+		.name = "i2c-at91sam9261",
+		.driver_data = (unsigned long) &at91sam9261_config,
+	}, {
+		.name = "i2c-at91sam9260",
+		.driver_data = (unsigned long) &at91sam9260_config,
+	}, {
+		.name = "i2c-at91sam9g20",
+		.driver_data = (unsigned long) &at91sam9g20_config,
+	}, {
+		.name = "i2c-at91sam9g10",
+		.driver_data = (unsigned long) &at91sam9g10_config,
+	}, {
+		/* sentinel */
+	}
+};
+
+#if defined(CONFIG_OF)
+static struct at91_twi_pdata at91sam9x5_config = {
+	.clk_max_div = 7,
+	.clk_offset = 4,
+	.has_unre_flag = false,
+	.has_alt_cmd = false,
+	.has_hold_field = false,
+};
+
+static struct at91_twi_pdata sama5d4_config = {
+	.clk_max_div = 7,
+	.clk_offset = 4,
+	.has_unre_flag = false,
+	.has_alt_cmd = false,
+	.has_hold_field = true,
+};
+
+static struct at91_twi_pdata sama5d2_config = {
+	.clk_max_div = 7,
+	.clk_offset = 4,
+	.has_unre_flag = true,
+	.has_alt_cmd = true,
+	.has_hold_field = true,
+};
+
+static const struct of_device_id atmel_twi_dt_ids[] = {
+	{
+		.compatible = "atmel,at91rm9200-i2c",
+		.data = &at91rm9200_config,
+	} , {
+		.compatible = "atmel,at91sam9260-i2c",
+		.data = &at91sam9260_config,
+	} , {
+		.compatible = "atmel,at91sam9261-i2c",
+		.data = &at91sam9261_config,
+	} , {
+		.compatible = "atmel,at91sam9g20-i2c",
+		.data = &at91sam9g20_config,
+	} , {
+		.compatible = "atmel,at91sam9g10-i2c",
+		.data = &at91sam9g10_config,
+	}, {
+		.compatible = "atmel,at91sam9x5-i2c",
+		.data = &at91sam9x5_config,
+	}, {
+		.compatible = "atmel,sama5d4-i2c",
+		.data = &sama5d4_config,
+	}, {
+		.compatible = "atmel,sama5d2-i2c",
+		.data = &sama5d2_config,
+	}, {
+		/* sentinel */
+	}
+};
+MODULE_DEVICE_TABLE(of, atmel_twi_dt_ids);
+#endif
+
+static struct at91_twi_pdata *at91_twi_get_driver_data(
+					struct platform_device *pdev)
+{
+	if (pdev->dev.of_node) {
+		const struct of_device_id *match;
+		match = of_match_node(atmel_twi_dt_ids, pdev->dev.of_node);
+		if (!match)
+			return NULL;
+		return (struct at91_twi_pdata *)match->data;
+	}
+	return (struct at91_twi_pdata *) platform_get_device_id(pdev)->driver_data;
+}
+
+static int at91_twi_probe(struct platform_device *pdev)
+{
+	struct at91_twi_dev *dev;
+	struct resource *mem;
+	int rc;
+	u32 phy_addr;
+
+	dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return -ENOMEM;
+
+	dev->dev = &pdev->dev;
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!mem)
+		return -ENODEV;
+	phy_addr = mem->start;
+
+	dev->pdata = at91_twi_get_driver_data(pdev);
+	if (!dev->pdata)
+		return -ENODEV;
+
+	dev->base = devm_ioremap_resource(&pdev->dev, mem);
+	if (IS_ERR(dev->base))
+		return PTR_ERR(dev->base);
+
+	dev->irq = platform_get_irq(pdev, 0);
+	if (dev->irq < 0)
+		return dev->irq;
+
+	platform_set_drvdata(pdev, dev);
+
+	dev->clk = devm_clk_get(dev->dev, NULL);
+	if (IS_ERR(dev->clk)) {
+		dev_err(dev->dev, "no clock defined\n");
+		return -ENODEV;
+	}
+	clk_prepare_enable(dev->clk);
+
+	snprintf(dev->adapter.name, sizeof(dev->adapter.name), "AT91");
+	i2c_set_adapdata(&dev->adapter, dev);
+	dev->adapter.owner = THIS_MODULE;
+	dev->adapter.class = I2C_CLASS_DEPRECATED;
+	dev->adapter.dev.parent = dev->dev;
+	dev->adapter.nr = pdev->id;
+	dev->adapter.timeout = AT91_I2C_TIMEOUT;
+	dev->adapter.dev.of_node = pdev->dev.of_node;
+
+	rc = at91_twi_probe_master(pdev, phy_addr, dev);
+	if (rc)
+		return rc;
+
+	at91_init_twi_bus(dev);
+
+	pm_runtime_set_autosuspend_delay(dev->dev, AUTOSUSPEND_TIMEOUT);
+	pm_runtime_use_autosuspend(dev->dev);
+	pm_runtime_set_active(dev->dev);
+	pm_runtime_enable(dev->dev);
+
+	rc = i2c_add_numbered_adapter(&dev->adapter);
+	if (rc) {
+		clk_disable_unprepare(dev->clk);
+
+		pm_runtime_disable(dev->dev);
+		pm_runtime_set_suspended(dev->dev);
+
+		return rc;
+	}
+
+	dev_info(dev->dev, "AT91 i2c bus driver (hw version: %#x).\n",
+		 at91_twi_read(dev, AT91_TWI_VER));
+	return 0;
+}
+
+static int at91_twi_remove(struct platform_device *pdev)
+{
+	struct at91_twi_dev *dev = platform_get_drvdata(pdev);
+
+	i2c_del_adapter(&dev->adapter);
+	clk_disable_unprepare(dev->clk);
+
+	pm_runtime_disable(dev->dev);
+	pm_runtime_set_suspended(dev->dev);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+
+static int at91_twi_runtime_suspend(struct device *dev)
+{
+	struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);
+
+	clk_disable_unprepare(twi_dev->clk);
+
+	pinctrl_pm_select_sleep_state(dev);
+
+	return 0;
+}
+
+static int at91_twi_runtime_resume(struct device *dev)
+{
+	struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);
+
+	pinctrl_pm_select_default_state(dev);
+
+	return clk_prepare_enable(twi_dev->clk);
+}
+
+static int at91_twi_suspend_noirq(struct device *dev)
+{
+	if (!pm_runtime_status_suspended(dev))
+		at91_twi_runtime_suspend(dev);
+
+	return 0;
+}
+
+static int at91_twi_resume_noirq(struct device *dev)
+{
+	struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);
+	int ret;
+
+	if (!pm_runtime_status_suspended(dev)) {
+		ret = at91_twi_runtime_resume(dev);
+		if (ret)
+			return ret;
+	}
+
+	pm_runtime_mark_last_busy(dev);
+	pm_request_autosuspend(dev);
+
+	at91_init_twi_bus(twi_dev);
+
+	return 0;
+}
+
+static const struct dev_pm_ops at91_twi_pm = {
+	.suspend_noirq	= at91_twi_suspend_noirq,
+	.resume_noirq	= at91_twi_resume_noirq,
+	.runtime_suspend	= at91_twi_runtime_suspend,
+	.runtime_resume		= at91_twi_runtime_resume,
+};
+
+#define at91_twi_pm_ops (&at91_twi_pm)
+#else
+#define at91_twi_pm_ops NULL
+#endif
+
+static struct platform_driver at91_twi_driver = {
+	.probe		= at91_twi_probe,
+	.remove		= at91_twi_remove,
+	.id_table	= at91_twi_devtypes,
+	.driver		= {
+		.name	= "at91_i2c",
+		.of_match_table = of_match_ptr(atmel_twi_dt_ids),
+		.pm	= at91_twi_pm_ops,
+	},
+};
+
+static int __init at91_twi_init(void)
+{
+	return platform_driver_register(&at91_twi_driver);
+}
+
+static void __exit at91_twi_exit(void)
+{
+	platform_driver_unregister(&at91_twi_driver);
+}
+
+subsys_initcall(at91_twi_init);
+module_exit(at91_twi_exit);
+
+MODULE_AUTHOR("Nikolaus Voss <[email protected]>");
+MODULE_DESCRIPTION("I2C (TWI) driver for Atmel AT91");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:at91_i2c");

drivers/i2c/busses/i2c-at91-master.c new file +804 -0

new file mode 100644
index 0000000..6dcdb04
@@ -0,0 +1,804 @@
+/*
+ *  i2c Support for Atmel's AT91 Two-Wire Interface (TWI)
+ *
+ *  Copyright (C) 2011 Weinmann Medical GmbH
+ *  Author: Nikolaus Voss <[email protected]>
+ *
+ *  Evolved from original work by:
+ *  Copyright (C) 2004 Rick Bronson
+ *  Converted to 2.6 by Andrew Victor <[email protected]>
+ *
+ *  Borrowed heavily from original work by:
+ *  Copyright (C) 2000 Philip Edelbrock <[email protected]>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ */
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/platform_data/dma-atmel.h>
+#include <linux/pm_runtime.h>
+
+#include "i2c-at91.h"
+
+void at91_init_twi_bus_master(struct at91_twi_dev *dev)
+{
+	/* FIFO should be enabled immediately after the software reset */
+	if (dev->fifo_size)
+		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_FIFOEN);
+	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_MSEN);
+	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SVDIS);
+	at91_twi_write(dev, AT91_TWI_CWGR, dev->twi_cwgr_reg);
+}
+
+/*
+ * Calculate symmetric clock as stated in datasheet:
+ * twi_clk = F_MAIN / (2 * (cdiv * (1 << ckdiv) + offset))
+ */
+static void at91_calc_twi_clock(struct at91_twi_dev *dev, int twi_clk)
+{
+	int ckdiv, cdiv, div, hold = 0;
+	struct at91_twi_pdata *pdata = dev->pdata;
+	int offset = pdata->clk_offset;
+	int max_ckdiv = pdata->clk_max_div;
+	u32 twd_hold_time_ns = 0;
+
+	div = max(0, (int)DIV_ROUND_UP(clk_get_rate(dev->clk),
+				       2 * twi_clk) - offset);
+	ckdiv = fls(div >> 8);
+	cdiv = div >> ckdiv;
+
+	if (ckdiv > max_ckdiv) {
+		dev_warn(dev->dev, "%d exceeds ckdiv max value which is %d.\n",
+			 ckdiv, max_ckdiv);
+		ckdiv = max_ckdiv;
+		cdiv = 255;
+	}
+
+	if (pdata->has_hold_field) {
+		of_property_read_u32(dev->dev->of_node, "i2c-sda-hold-time-ns",
+				     &twd_hold_time_ns);
+
+		/*
+		 * hold time = HOLD + 3 x T_peripheral_clock
+		 * Use clk rate in kHz to prevent overflows when computing
+		 * hold.
+		 */
+		hold = DIV_ROUND_UP(twd_hold_time_ns
+				    * (clk_get_rate(dev->clk) / 1000), 1000000);
+		hold -= 3;
+		if (hold < 0)
+			hold = 0;
+		if (hold > AT91_TWI_CWGR_HOLD_MAX) {
+			dev_warn(dev->dev,
+				 "HOLD field set to its maximum value (%d instead of %d)\n",
+				 AT91_TWI_CWGR_HOLD_MAX, hold);
+			hold = AT91_TWI_CWGR_HOLD_MAX;
+		}
+	}
+
+	dev->twi_cwgr_reg = (ckdiv << 16) | (cdiv << 8) | cdiv
+			    | AT91_TWI_CWGR_HOLD(hold);
+
+	dev_dbg(dev->dev, "cdiv %d ckdiv %d hold %d (%d ns)\n",
+		cdiv, ckdiv, hold, twd_hold_time_ns);
+}
+
+static void at91_twi_dma_cleanup(struct at91_twi_dev *dev)
+{
+	struct at91_twi_dma *dma = &dev->dma;
+
+	at91_twi_irq_save(dev);
+
+	if (dma->xfer_in_progress) {
+		if (dma->direction == DMA_FROM_DEVICE)
+			dmaengine_terminate_all(dma->chan_rx);
+		else
+			dmaengine_terminate_all(dma->chan_tx);
+		dma->xfer_in_progress = false;
+	}
+	if (dma->buf_mapped) {
+		dma_unmap_single(dev->dev, sg_dma_address(&dma->sg[0]),
+				 dev->buf_len, dma->direction);
+		dma->buf_mapped = false;
+	}
+
+	at91_twi_irq_restore(dev);
+}
+
+static void at91_twi_write_next_byte(struct at91_twi_dev *dev)
+{
+	if (!dev->buf_len)
+		return;
+
+	/* 8bit write works with and without FIFO */
+	writeb_relaxed(*dev->buf, dev->base + AT91_TWI_THR);
+
+	/* send stop when last byte has been written */
+	if (--dev->buf_len == 0)
+		if (!dev->use_alt_cmd)
+			at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
+
+	dev_dbg(dev->dev, "wrote 0x%x, to go %zu\n", *dev->buf, dev->buf_len);
+
+	++dev->buf;
+}
+
+static void at91_twi_write_data_dma_callback(void *data)
+{
+	struct at91_twi_dev *dev = (struct at91_twi_dev *)data;
+
+	dma_unmap_single(dev->dev, sg_dma_address(&dev->dma.sg[0]),
+			 dev->buf_len, DMA_TO_DEVICE);
+
+	/*
+	 * When this callback is called, THR/TX FIFO is likely not to be empty
+	 * yet. So we have to wait for TXCOMP or NACK bits to be set into the
+	 * Status Register to be sure that the STOP bit has been sent and the
+	 * transfer is completed. The NACK interrupt has already been enabled,
+	 * we just have to enable TXCOMP one.
+	 */
+	at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_TXCOMP);
+	if (!dev->use_alt_cmd)
+		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
+}
+
+static void at91_twi_write_data_dma(struct at91_twi_dev *dev)
+{
+	dma_addr_t dma_addr;
+	struct dma_async_tx_descriptor *txdesc;
+	struct at91_twi_dma *dma = &dev->dma;
+	struct dma_chan *chan_tx = dma->chan_tx;
+	unsigned int sg_len = 1;
+
+	if (!dev->buf_len)
+		return;
+
+	dma->direction = DMA_TO_DEVICE;
+
+	at91_twi_irq_save(dev);
+	dma_addr = dma_map_single(dev->dev, dev->buf, dev->buf_len,
+				  DMA_TO_DEVICE);
+	if (dma_mapping_error(dev->dev, dma_addr)) {
+		dev_err(dev->dev, "dma map failed\n");
+		return;
+	}
+	dma->buf_mapped = true;
+	at91_twi_irq_restore(dev);
+
+	if (dev->fifo_size) {
+		size_t part1_len, part2_len;
+		struct scatterlist *sg;
+		unsigned fifo_mr;
+
+		sg_len = 0;
+
+		part1_len = dev->buf_len & ~0x3;
+		if (part1_len) {
+			sg = &dma->sg[sg_len++];
+			sg_dma_len(sg) = part1_len;
+			sg_dma_address(sg) = dma_addr;
+		}
+
+		part2_len = dev->buf_len & 0x3;
+		if (part2_len) {
+			sg = &dma->sg[sg_len++];
+			sg_dma_len(sg) = part2_len;
+			sg_dma_address(sg) = dma_addr + part1_len;
+		}
+
+		/*
+		 * DMA controller is triggered when at least 4 data can be
+		 * written into the TX FIFO
+		 */
+		fifo_mr = at91_twi_read(dev, AT91_TWI_FMR);
+		fifo_mr &= ~AT91_TWI_FMR_TXRDYM_MASK;
+		fifo_mr |= AT91_TWI_FMR_TXRDYM(AT91_TWI_FOUR_DATA);
+		at91_twi_write(dev, AT91_TWI_FMR, fifo_mr);
+	} else {
+		sg_dma_len(&dma->sg[0]) = dev->buf_len;
+		sg_dma_address(&dma->sg[0]) = dma_addr;
+	}
+
+	txdesc = dmaengine_prep_slave_sg(chan_tx, dma->sg, sg_len,
+					 DMA_MEM_TO_DEV,
+					 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+	if (!txdesc) {
+		dev_err(dev->dev, "dma prep slave sg failed\n");
+		goto error;
+	}
+
+	txdesc->callback = at91_twi_write_data_dma_callback;
+	txdesc->callback_param = dev;
+
+	dma->xfer_in_progress = true;
+	dmaengine_submit(txdesc);
+	dma_async_issue_pending(chan_tx);
+
+	return;
+
+error:
+	at91_twi_dma_cleanup(dev);
+}
+
+static void at91_twi_read_next_byte(struct at91_twi_dev *dev)
+{
+	/*
+	 * If we are in this case, it means there is garbage data in RHR, so
+	 * delete them.
+	 */
+	if (!dev->buf_len) {
+		at91_twi_read(dev, AT91_TWI_RHR);
+		return;
+	}
+
+	/* 8bit read works with and without FIFO */
+	*dev->buf = readb_relaxed(dev->base + AT91_TWI_RHR);
+	--dev->buf_len;
+
+	/* return if aborting, we only needed to read RHR to clear RXRDY*/
+	if (dev->recv_len_abort)
+		return;
+
+	/* handle I2C_SMBUS_BLOCK_DATA */
+	if (unlikely(dev->msg->flags & I2C_M_RECV_LEN)) {
+		/* ensure length byte is a valid value */
+		if (*dev->buf <= I2C_SMBUS_BLOCK_MAX && *dev->buf > 0) {
+			dev->msg->flags &= ~I2C_M_RECV_LEN;
+			dev->buf_len += *dev->buf;
+			dev->msg->len = dev->buf_len + 1;
+			dev_dbg(dev->dev, "received block length %zu\n",
+					 dev->buf_len);
+		} else {
+			/* abort and send the stop by reading one more byte */
+			dev->recv_len_abort = true;
+			dev->buf_len = 1;
+		}
+	}
+
+	/* send stop if second but last byte has been read */
+	if (!dev->use_alt_cmd && dev->buf_len == 1)
+		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
+
+	dev_dbg(dev->dev, "read 0x%x, to go %zu\n", *dev->buf, dev->buf_len);
+
+	++dev->buf;
+}
+
+static void at91_twi_read_data_dma_callback(void *data)
+{
+	struct at91_twi_dev *dev = (struct at91_twi_dev *)data;
+	unsigned ier = AT91_TWI_TXCOMP;
+
+	dma_unmap_single(dev->dev, sg_dma_address(&dev->dma.sg[0]),
+			 dev->buf_len, DMA_FROM_DEVICE);
+
+	if (!dev->use_alt_cmd) {
+		/* The last two bytes have to be read without using dma */
+		dev->buf += dev->buf_len - 2;
+		dev->buf_len = 2;
+		ier |= AT91_TWI_RXRDY;
+	}
+	at91_twi_write(dev, AT91_TWI_IER, ier);
+}
+
+static void at91_twi_read_data_dma(struct at91_twi_dev *dev)
+{
+	dma_addr_t dma_addr;
+	struct dma_async_tx_descriptor *rxdesc;
+	struct at91_twi_dma *dma = &dev->dma;
+	struct dma_chan *chan_rx = dma->chan_rx;
+	size_t buf_len;
+
+	buf_len = (dev->use_alt_cmd) ? dev->buf_len : dev->buf_len - 2;
+	dma->direction = DMA_FROM_DEVICE;
+
+	/* Keep in mind that we won't use dma to read the last two bytes */
+	at91_twi_irq_save(dev);
+	dma_addr = dma_map_single(dev->dev, dev->buf, buf_len, DMA_FROM_DEVICE);
+	if (dma_mapping_error(dev->dev, dma_addr)) {
+		dev_err(dev->dev, "dma map failed\n");
+		return;
+	}
+	dma->buf_mapped = true;
+	at91_twi_irq_restore(dev);
+
+	if (dev->fifo_size && IS_ALIGNED(buf_len, 4)) {
+		unsigned fifo_mr;
+
+		/*
+		 * DMA controller is triggered when at least 4 data can be
+		 * read from the RX FIFO
+		 */
+		fifo_mr = at91_twi_read(dev, AT91_TWI_FMR);
+		fifo_mr &= ~AT91_TWI_FMR_RXRDYM_MASK;
+		fifo_mr |= AT91_TWI_FMR_RXRDYM(AT91_TWI_FOUR_DATA);
+		at91_twi_write(dev, AT91_TWI_FMR, fifo_mr);
+	}
+
+	sg_dma_len(&dma->sg[0]) = buf_len;
+	sg_dma_address(&dma->sg[0]) = dma_addr;
+
+	rxdesc = dmaengine_prep_slave_sg(chan_rx, dma->sg, 1, DMA_DEV_TO_MEM,
+					 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+	if (!rxdesc) {
+		dev_err(dev->dev, "dma prep slave sg failed\n");
+		goto error;
+	}
+
+	rxdesc->callback = at91_twi_read_data_dma_callback;
+	rxdesc->callback_param = dev;
+
+	dma->xfer_in_progress = true;
+	dmaengine_submit(rxdesc);
+	dma_async_issue_pending(dma->chan_rx);
+
+	return;
+
+error:
+	at91_twi_dma_cleanup(dev);
+}
+
+static irqreturn_t atmel_twi_interrupt(int irq, void *dev_id)
+{
+	struct at91_twi_dev *dev = dev_id;
+	const unsigned status = at91_twi_read(dev, AT91_TWI_SR);
+	const unsigned irqstatus = status & at91_twi_read(dev, AT91_TWI_IMR);
+
+	if (!irqstatus)
+		return IRQ_NONE;
+	/*
+	 * In reception, the behavior of the twi device (before sama5d2) is
+	 * weird. There is some magic about RXRDY flag! When a data has been
+	 * almost received, the reception of a new one is anticipated if there
+	 * is no stop command to send. That is the reason why ask for sending
+	 * the stop command not on the last data but on the second last one.
+	 *
+	 * Unfortunately, we could still have the RXRDY flag set even if the
+	 * transfer is done and we have read the last data. It might happen
+	 * when the i2c slave device sends too quickly data after receiving the
+	 * ack from the master. The data has been almost received before having
+	 * the order to send stop. In this case, sending the stop command could
+	 * cause a RXRDY interrupt with a TXCOMP one. It is better to manage
+	 * the RXRDY interrupt first in order to not keep garbage data in the
+	 * Receive Holding Register for the next transfer.
+	 */
+	if (irqstatus & AT91_TWI_RXRDY)
+		at91_twi_read_next_byte(dev);
+
+	/*
+	 * When a NACK condition is detected, the I2C controller sets the NACK,
+	 * TXCOMP and TXRDY bits all together in the Status Register (SR).
+	 *
+	 * 1 - Handling NACK errors with CPU write transfer.
+	 *
+	 * In such case, we should not write the next byte into the Transmit
+	 * Holding Register (THR) otherwise the I2C controller would start a new
+	 * transfer and the I2C slave is likely to reply by another NACK.
+	 *
+	 * 2 - Handling NACK errors with DMA write transfer.
+	 *
+	 * By setting the TXRDY bit in the SR, the I2C controller also triggers
+	 * the DMA controller to write the next data into the THR. Then the
+	 * result depends on the hardware version of the I2C controller.
+	 *
+	 * 2a - Without support of the Alternative Command mode.
+	 *
+	 * This is the worst case: the DMA controller is triggered to write the
+	 * next data into the THR, hence starting a new transfer: the I2C slave
+	 * is likely to reply by another NACK.
+	 * Concurrently, this interrupt handler is likely to be called to manage
+	 * the first NACK before the I2C controller detects the second NACK and
+	 * sets once again the NACK bit into the SR.
+	 * When handling the first NACK, this interrupt handler disables the I2C
+	 * controller interruptions, especially the NACK interrupt.
+	 * Hence, the NACK bit is pending into the SR. This is why we should
+	 * read the SR to clear all pending interrupts at the beginning of
+	 * at91_do_twi_transfer() before actually starting a new transfer.
+	 *
+	 * 2b - With support of the Alternative Command mode.
+	 *
+	 * When a NACK condition is detected, the I2C controller also locks the
+	 * THR (and sets the LOCK bit in the SR): even though the DMA controller
+	 * is triggered by the TXRDY bit to write the next data into the THR,
+	 * this data actually won't go on the I2C bus hence a second NACK is not
+	 * generated.
+	 */
+	if (irqstatus & (AT91_TWI_TXCOMP | AT91_TWI_NACK)) {
+		at91_disable_twi_interrupts(dev);
+		complete(&dev->cmd_complete);
+	} else if (irqstatus & AT91_TWI_TXRDY) {
+		at91_twi_write_next_byte(dev);
+	}
+
+	/* catch error flags */
+	dev->transfer_status |= status;
+
+	return IRQ_HANDLED;
+}
+
+static int at91_do_twi_transfer(struct at91_twi_dev *dev)
+{
+	int ret;
+	unsigned long time_left;
+	bool has_unre_flag = dev->pdata->has_unre_flag;
+	bool has_alt_cmd = dev->pdata->has_alt_cmd;
+
+	/*
+	 * WARNING: the TXCOMP bit in the Status Register is NOT a clear on
+	 * read flag but shows the state of the transmission at the time the
+	 * Status Register is read. According to the programmer datasheet,
+	 * TXCOMP is set when both holding register and internal shifter are
+	 * empty and STOP condition has been sent.
+	 * Consequently, we should enable NACK interrupt rather than TXCOMP to
+	 * detect transmission failure.
+	 * Indeed let's take the case of an i2c write command using DMA.
+	 * Whenever the slave doesn't acknowledge a byte, the LOCK, NACK and
+	 * TXCOMP bits are set together into the Status Register.
+	 * LOCK is a clear on write bit, which is set to prevent the DMA
+	 * controller from sending new data on the i2c bus after a NACK
+	 * condition has happened. Once locked, this i2c peripheral stops
+	 * triggering the DMA controller for new data but it is more than
+	 * likely that a new DMA transaction is already in progress, writing
+	 * into the Transmit Holding Register. Since the peripheral is locked,
+	 * these new data won't be sent to the i2c bus but they will remain
+	 * into the Transmit Holding Register, so TXCOMP bit is cleared.
+	 * Then when the interrupt handler is called, the Status Register is
+	 * read: the TXCOMP bit is clear but NACK bit is still set. The driver
+	 * manage the error properly, without waiting for timeout.
+	 * This case can be reproduced easyly when writing into an at24 eeprom.
+	 *
+	 * Besides, the TXCOMP bit is already set before the i2c transaction
+	 * has been started. For read transactions, this bit is cleared when
+	 * writing the START bit into the Control Register. So the
+	 * corresponding interrupt can safely be enabled just after.
+	 * However for write transactions managed by the CPU, we first write
+	 * into THR, so TXCOMP is cleared. Then we can safely enable TXCOMP
+	 * interrupt. If TXCOMP interrupt were enabled before writing into THR,
+	 * the interrupt handler would be called immediately and the i2c command
+	 * would be reported as completed.
+	 * Also when a write transaction is managed by the DMA controller,
+	 * enabling the TXCOMP interrupt in this function may lead to a race
+	 * condition since we don't know whether the TXCOMP interrupt is enabled
+	 * before or after the DMA has started to write into THR. So the TXCOMP
+	 * interrupt is enabled later by at91_twi_write_data_dma_callback().
+	 * Immediately after in that DMA callback, if the alternative command
+	 * mode is not used, we still need to send the STOP condition manually
+	 * writing the corresponding bit into the Control Register.
+	 */
+
+	dev_dbg(dev->dev, "transfer: %s %zu bytes.\n",
+		(dev->msg->flags & I2C_M_RD) ? "read" : "write", dev->buf_len);
+
+	reinit_completion(&dev->cmd_complete);
+	dev->transfer_status = 0;
+
+	/* Clear pending interrupts, such as NACK. */
+	at91_twi_read(dev, AT91_TWI_SR);
+
+	if (dev->fifo_size) {
+		unsigned fifo_mr = at91_twi_read(dev, AT91_TWI_FMR);
+
+		/* Reset FIFO mode register */
+		fifo_mr &= ~(AT91_TWI_FMR_TXRDYM_MASK |
+			     AT91_TWI_FMR_RXRDYM_MASK);
+		fifo_mr |= AT91_TWI_FMR_TXRDYM(AT91_TWI_ONE_DATA);
+		fifo_mr |= AT91_TWI_FMR_RXRDYM(AT91_TWI_ONE_DATA);
+		at91_twi_write(dev, AT91_TWI_FMR, fifo_mr);
+
+		/* Flush FIFOs */
+		at91_twi_write(dev, AT91_TWI_CR,
+			       AT91_TWI_THRCLR | AT91_TWI_RHRCLR);
+	}
+
+	if (!dev->buf_len) {
+		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_QUICK);
+		at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_TXCOMP);
+	} else if (dev->msg->flags & I2C_M_RD) {
+		unsigned start_flags = AT91_TWI_START;
+
+		/* if only one byte is to be read, immediately stop transfer */
+		if (!dev->use_alt_cmd && dev->buf_len <= 1 &&
+		    !(dev->msg->flags & I2C_M_RECV_LEN))
+			start_flags |= AT91_TWI_STOP;
+		at91_twi_write(dev, AT91_TWI_CR, start_flags);
+		/*
+		 * When using dma without alternative command mode, the last
+		 * byte has to be read manually in order to not send the stop
+		 * command too late and then to receive extra data.
+		 * In practice, there are some issues if you use the dma to
+		 * read n-1 bytes because of latency.
+		 * Reading n-2 bytes with dma and the two last ones manually
+		 * seems to be the best solution.
+		 */
+		if (dev->use_dma && (dev->buf_len > AT91_I2C_DMA_THRESHOLD)) {
+			at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_NACK);
+			at91_twi_read_data_dma(dev);
+		} else {
+			at91_twi_write(dev, AT91_TWI_IER,
+				       AT91_TWI_TXCOMP |
+				       AT91_TWI_NACK |
+				       AT91_TWI_RXRDY);
+		}
+	} else {
+		if (dev->use_dma && (dev->buf_len > AT91_I2C_DMA_THRESHOLD)) {
+			at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_NACK);
+			at91_twi_write_data_dma(dev);
+		} else {
+			at91_twi_write_next_byte(dev);
+			at91_twi_write(dev, AT91_TWI_IER,
+				       AT91_TWI_TXCOMP |
+				       AT91_TWI_NACK |
+				       AT91_TWI_TXRDY);
+		}
+	}
+
+	time_left = wait_for_completion_timeout(&dev->cmd_complete,
+					      dev->adapter.timeout);
+	if (time_left == 0) {
+		dev->transfer_status |= at91_twi_read(dev, AT91_TWI_SR);
+		dev_err(dev->dev, "controller timed out\n");
+		at91_init_twi_bus(dev);
+		ret = -ETIMEDOUT;
+		goto error;
+	}
+	if (dev->transfer_status & AT91_TWI_NACK) {
+		dev_dbg(dev->dev, "received nack\n");
+		ret = -EREMOTEIO;
+		goto error;
+	}
+	if (dev->transfer_status & AT91_TWI_OVRE) {
+		dev_err(dev->dev, "overrun while reading\n");
+		ret = -EIO;
+		goto error;
+	}
+	if (has_unre_flag && dev->transfer_status & AT91_TWI_UNRE) {
+		dev_err(dev->dev, "underrun while writing\n");
+		ret = -EIO;
+		goto error;
+	}
+	if ((has_alt_cmd || dev->fifo_size) &&
+	    (dev->transfer_status & AT91_TWI_LOCK)) {
+		dev_err(dev->dev, "tx locked\n");
+		ret = -EIO;
+		goto error;
+	}
+	if (dev->recv_len_abort) {
+		dev_err(dev->dev, "invalid smbus block length recvd\n");
+		ret = -EPROTO;
+		goto error;
+	}
+
+	dev_dbg(dev->dev, "transfer complete\n");
+
+	return 0;
+
+error:
+	/* first stop DMA transfer if still in progress */
+	at91_twi_dma_cleanup(dev);
+	/* then flush THR/FIFO and unlock TX if locked */
+	if ((has_alt_cmd || dev->fifo_size) &&
+	    (dev->transfer_status & AT91_TWI_LOCK)) {
+		dev_dbg(dev->dev, "unlock tx\n");
+		at91_twi_write(dev, AT91_TWI_CR,
+			       AT91_TWI_THRCLR | AT91_TWI_LOCKCLR);
+	}
+	return ret;
+}
+
+static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num)
+{
+	struct at91_twi_dev *dev = i2c_get_adapdata(adap);
+	int ret;
+	unsigned int_addr_flag = 0;
+	struct i2c_msg *m_start = msg;
+	bool is_read;
+
+	dev_dbg(&adap->dev, "at91_xfer: processing %d messages:\n", num);
+
+	ret = pm_runtime_get_sync(dev->dev);
+	if (ret < 0)
+		goto out;
+
+	if (num == 2) {
+		int internal_address = 0;
+		int i;
+
+		/* 1st msg is put into the internal address, start with 2nd */
+		m_start = &msg[1];
+		for (i = 0; i < msg->len; ++i) {
+			const unsigned addr = msg->buf[msg->len - 1 - i];
+
+			internal_address |= addr << (8 * i);
+			int_addr_flag += AT91_TWI_IADRSZ_1;
+		}
+		at91_twi_write(dev, AT91_TWI_IADR, internal_address);
+	}
+
+	dev->use_alt_cmd = false;
+	is_read = (m_start->flags & I2C_M_RD);
+	if (dev->pdata->has_alt_cmd) {
+		if (m_start->len > 0 &&
+		    m_start->len < AT91_I2C_MAX_ALT_CMD_DATA_SIZE) {
+			at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_ACMEN);
+			at91_twi_write(dev, AT91_TWI_ACR,
+				       AT91_TWI_ACR_DATAL(m_start->len) |
+				       ((is_read) ? AT91_TWI_ACR_DIR : 0));
+			dev->use_alt_cmd = true;
+		} else {
+			at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_ACMDIS);
+		}
+	}
+
+	at91_twi_write(dev, AT91_TWI_MMR,
+		       (m_start->addr << 16) |
+		       int_addr_flag |
+		       ((!dev->use_alt_cmd && is_read) ? AT91_TWI_MREAD : 0));
+
+	dev->buf_len = m_start->len;
+	dev->buf = m_start->buf;
+	dev->msg = m_start;
+	dev->recv_len_abort = false;
+
+	ret = at91_do_twi_transfer(dev);
+
+	ret = (ret < 0) ? ret : num;
+out:
+	pm_runtime_mark_last_busy(dev->dev);
+	pm_runtime_put_autosuspend(dev->dev);
+
+	return ret;
+}
+
+/*
+ * The hardware can handle at most two messages concatenated by a
+ * repeated start via it's internal address feature.
+ */
+static const struct i2c_adapter_quirks at91_twi_quirks = {
+	.flags = I2C_AQ_COMB | I2C_AQ_COMB_WRITE_FIRST | I2C_AQ_COMB_SAME_ADDR,
+	.max_comb_1st_msg_len = 3,
+};
+
+static u32 at91_twi_func(struct i2c_adapter *adapter)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL
+		| I2C_FUNC_SMBUS_READ_BLOCK_DATA;
+}
+
+static const struct i2c_algorithm at91_twi_algorithm = {
+	.master_xfer	= at91_twi_xfer,
+	.functionality	= at91_twi_func,
+};
+
+static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr)
+{
+	int ret = 0;
+	struct dma_slave_config slave_config;
+	struct at91_twi_dma *dma = &dev->dma;
+	enum dma_slave_buswidth addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+
+	/*
+	 * The actual width of the access will be chosen in
+	 * dmaengine_prep_slave_sg():
+	 * for each buffer in the scatter-gather list, if its size is aligned
+	 * to addr_width then addr_width accesses will be performed to transfer
+	 * the buffer. On the other hand, if the buffer size is not aligned to
+	 * addr_width then the buffer is transferred using single byte accesses.
+	 * Please refer to the Atmel eXtended DMA controller driver.
+	 * When FIFOs are used, the TXRDYM threshold can always be set to
+	 * trigger the XDMAC when at least 4 data can be written into the TX
+	 * FIFO, even if single byte accesses are performed.
+	 * However the RXRDYM threshold must be set to fit the access width,
+	 * deduced from buffer length, so the XDMAC is triggered properly to
+	 * read data from the RX FIFO.
+	 */
+	if (dev->fifo_size)
+		addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+
+	memset(&slave_config, 0, sizeof(slave_config));
+	slave_config.src_addr = (dma_addr_t)phy_addr + AT91_TWI_RHR;
+	slave_config.src_addr_width = addr_width;
+	slave_config.src_maxburst = 1;
+	slave_config.dst_addr = (dma_addr_t)phy_addr + AT91_TWI_THR;
+	slave_config.dst_addr_width = addr_width;
+	slave_config.dst_maxburst = 1;
+	slave_config.device_fc = false;
+
+	dma->chan_tx = dma_request_slave_channel_reason(dev->dev, "tx");
+	if (IS_ERR(dma->chan_tx)) {
+		ret = PTR_ERR(dma->chan_tx);
+		dma->chan_tx = NULL;
+		goto error;
+	}
+
+	dma->chan_rx = dma_request_slave_channel_reason(dev->dev, "rx");
+	if (IS_ERR(dma->chan_rx)) {
+		ret = PTR_ERR(dma->chan_rx);
+		dma->chan_rx = NULL;
+		goto error;
+	}
+
+	slave_config.direction = DMA_MEM_TO_DEV;
+	if (dmaengine_slave_config(dma->chan_tx, &slave_config)) {
+		dev_err(dev->dev, "failed to configure tx channel\n");
+		ret = -EINVAL;
+		goto error;
+	}
+
+	slave_config.direction = DMA_DEV_TO_MEM;
+	if (dmaengine_slave_config(dma->chan_rx, &slave_config)) {
+		dev_err(dev->dev, "failed to configure rx channel\n");
+		ret = -EINVAL;
+		goto error;
+	}
+
+	sg_init_table(dma->sg, 2);
+	dma->buf_mapped = false;
+	dma->xfer_in_progress = false;
+	dev->use_dma = true;
+
+	dev_info(dev->dev, "using %s (tx) and %s (rx) for DMA transfers\n",
+		 dma_chan_name(dma->chan_tx), dma_chan_name(dma->chan_rx));
+
+	return ret;
+
+error:
+	if (ret != -EPROBE_DEFER)
+		dev_info(dev->dev, "can't get DMA channel, continue without DMA support\n");
+	if (dma->chan_rx)
+		dma_release_channel(dma->chan_rx);
+	if (dma->chan_tx)
+		dma_release_channel(dma->chan_tx);
+	return ret;
+}
+
+int at91_twi_probe_master(struct platform_device *pdev,
+			  u32 phy_addr, struct at91_twi_dev *dev)
+{
+	int rc;
+	u32 bus_clk_rate;
+
+	init_completion(&dev->cmd_complete);
+
+	rc = devm_request_irq(&pdev->dev, dev->irq, atmel_twi_interrupt, 0,
+			      dev_name(dev->dev), dev);
+	if (rc) {
+		dev_err(dev->dev, "Cannot get irq %d: %d\n", dev->irq, rc);
+		return rc;
+	}
+
+	if (dev->dev->of_node) {
+		rc = at91_twi_configure_dma(dev, phy_addr);
+		if (rc == -EPROBE_DEFER)
+			return rc;
+	}
+
+	if (!of_property_read_u32(pdev->dev.of_node, "atmel,fifo-size",
+				  &dev->fifo_size)) {
+		dev_info(dev->dev, "Using FIFO (%u data)\n", dev->fifo_size);
+	}
+
+	rc = of_property_read_u32(dev->dev->of_node, "clock-frequency",
+				  &bus_clk_rate);
+	if (rc)
+		bus_clk_rate = DEFAULT_TWI_CLK_HZ;
+
+	at91_calc_twi_clock(dev, bus_clk_rate);
+
+	dev->adapter.algo = &at91_twi_algorithm;
+	dev->adapter.quirks = &at91_twi_quirks;
+
+	return 0;
+}

drivers/i2c/busses/i2c-at91.c deleted +0 -1263

deleted file mode 100644
index 73b6582..0000000
@@ -1,1263 +0,0 @@
-/*
- *  i2c Support for Atmel's AT91 Two-Wire Interface (TWI)
- *
- *  Copyright (C) 2011 Weinmann Medical GmbH
- *  Author: Nikolaus Voss <[email protected]>
- *
- *  Evolved from original work by:
- *  Copyright (C) 2004 Rick Bronson
- *  Converted to 2.6 by Andrew Victor <[email protected]>
- *
- *  Borrowed heavily from original work by:
- *  Copyright (C) 2000 Philip Edelbrock <[email protected]>
- *
- *  This program is free software; you can redistribute it and/or modify
- *  it under the terms of the GNU General Public License as published by
- *  the Free Software Foundation; either version 2 of the License, or
- *  (at your option) any later version.
- */
-
-#include <linux/clk.h>
-#include <linux/completion.h>
-#include <linux/dma-mapping.h>
-#include <linux/dmaengine.h>
-#include <linux/err.h>
-#include <linux/i2c.h>
-#include <linux/interrupt.h>
-#include <linux/io.h>
-#include <linux/module.h>
-#include <linux/of.h>
-#include <linux/of_device.h>
-#include <linux/platform_device.h>
-#include <linux/slab.h>
-#include <linux/platform_data/dma-atmel.h>
-#include <linux/pm_runtime.h>
-#include <linux/pinctrl/consumer.h>
-
-#define DEFAULT_TWI_CLK_HZ		100000		/* max 400 Kbits/s */
-#define AT91_I2C_TIMEOUT	msecs_to_jiffies(100)	/* transfer timeout */
-#define AT91_I2C_DMA_THRESHOLD	8			/* enable DMA if transfer size is bigger than this threshold */
-#define AUTOSUSPEND_TIMEOUT		2000
-#define AT91_I2C_MAX_ALT_CMD_DATA_SIZE	256
-
-/* AT91 TWI register definitions */
-#define	AT91_TWI_CR		0x0000	/* Control Register */
-#define	AT91_TWI_START		BIT(0)	/* Send a Start Condition */
-#define	AT91_TWI_STOP		BIT(1)	/* Send a Stop Condition */
-#define	AT91_TWI_MSEN		BIT(2)	/* Master Transfer Enable */
-#define	AT91_TWI_MSDIS		BIT(3)	/* Master Transfer Disable */
-#define	AT91_TWI_SVEN		BIT(4)	/* Slave Transfer Enable */
-#define	AT91_TWI_SVDIS		BIT(5)	/* Slave Transfer Disable */
-#define	AT91_TWI_QUICK		BIT(6)	/* SMBus quick command */
-#define	AT91_TWI_SWRST		BIT(7)	/* Software Reset */
-#define	AT91_TWI_ACMEN		BIT(16) /* Alternative Command Mode Enable */
-#define	AT91_TWI_ACMDIS		BIT(17) /* Alternative Command Mode Disable */
-#define	AT91_TWI_THRCLR		BIT(24) /* Transmit Holding Register Clear */
-#define	AT91_TWI_RHRCLR		BIT(25) /* Receive Holding Register Clear */
-#define	AT91_TWI_LOCKCLR	BIT(26) /* Lock Clear */
-#define	AT91_TWI_FIFOEN		BIT(28) /* FIFO Enable */
-#define	AT91_TWI_FIFODIS	BIT(29) /* FIFO Disable */
-
-#define	AT91_TWI_MMR		0x0004	/* Master Mode Register */
-#define	AT91_TWI_IADRSZ_1	0x0100	/* Internal Device Address Size */
-#define	AT91_TWI_MREAD		BIT(12)	/* Master Read Direction */
-
-#define	AT91_TWI_IADR		0x000c	/* Internal Address Register */
-
-#define	AT91_TWI_CWGR		0x0010	/* Clock Waveform Generator Reg */
-#define	AT91_TWI_CWGR_HOLD_MAX	0x1f
-#define	AT91_TWI_CWGR_HOLD(x)	(((x) & AT91_TWI_CWGR_HOLD_MAX) << 24)
-
-#define	AT91_TWI_SR		0x0020	/* Status Register */
-#define	AT91_TWI_TXCOMP		BIT(0)	/* Transmission Complete */
-#define	AT91_TWI_RXRDY		BIT(1)	/* Receive Holding Register Ready */
-#define	AT91_TWI_TXRDY		BIT(2)	/* Transmit Holding Register Ready */
-#define	AT91_TWI_OVRE		BIT(6)	/* Overrun Error */
-#define	AT91_TWI_UNRE		BIT(7)	/* Underrun Error */
-#define	AT91_TWI_NACK		BIT(8)	/* Not Acknowledged */
-#define	AT91_TWI_LOCK		BIT(23) /* TWI Lock due to Frame Errors */
-
-#define	AT91_TWI_INT_MASK \
-	(AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY | AT91_TWI_NACK)
-
-#define	AT91_TWI_IER		0x0024	/* Interrupt Enable Register */
-#define	AT91_TWI_IDR		0x0028	/* Interrupt Disable Register */
-#define	AT91_TWI_IMR		0x002c	/* Interrupt Mask Register */
-#define	AT91_TWI_RHR		0x0030	/* Receive Holding Register */
-#define	AT91_TWI_THR		0x0034	/* Transmit Holding Register */
-
-#define	AT91_TWI_ACR		0x0040	/* Alternative Command Register */
-#define	AT91_TWI_ACR_DATAL(len)	((len) & 0xff)
-#define	AT91_TWI_ACR_DIR	BIT(8)
-
-#define	AT91_TWI_FMR		0x0050	/* FIFO Mode Register */
-#define	AT91_TWI_FMR_TXRDYM(mode)	(((mode) & 0x3) << 0)
-#define	AT91_TWI_FMR_TXRDYM_MASK	(0x3 << 0)
-#define	AT91_TWI_FMR_RXRDYM(mode)	(((mode) & 0x3) << 4)
-#define	AT91_TWI_FMR_RXRDYM_MASK	(0x3 << 4)
-#define	AT91_TWI_ONE_DATA	0x0
-#define	AT91_TWI_TWO_DATA	0x1
-#define	AT91_TWI_FOUR_DATA	0x2
-
-#define	AT91_TWI_FLR		0x0054	/* FIFO Level Register */
-
-#define	AT91_TWI_FSR		0x0060	/* FIFO Status Register */
-#define	AT91_TWI_FIER		0x0064	/* FIFO Interrupt Enable Register */
-#define	AT91_TWI_FIDR		0x0068	/* FIFO Interrupt Disable Register */
-#define	AT91_TWI_FIMR		0x006c	/* FIFO Interrupt Mask Register */
-
-#define	AT91_TWI_VER		0x00fc	/* Version Register */
-
-struct at91_twi_pdata {
-	unsigned clk_max_div;
-	unsigned clk_offset;
-	bool has_unre_flag;
-	bool has_alt_cmd;
-	bool has_hold_field;
-	struct at_dma_slave dma_slave;
-};
-
-struct at91_twi_dma {
-	struct dma_chan *chan_rx;
-	struct dma_chan *chan_tx;
-	struct scatterlist sg[2];
-	struct dma_async_tx_descriptor *data_desc;
-	enum dma_data_direction direction;
-	bool buf_mapped;
-	bool xfer_in_progress;
-};
-
-struct at91_twi_dev {
-	struct device *dev;
-	void __iomem *base;
-	struct completion cmd_complete;
-	struct clk *clk;
-	u8 *buf;
-	size_t buf_len;
-	struct i2c_msg *msg;
-	int irq;
-	unsigned imr;
-	unsigned transfer_status;
-	struct i2c_adapter adapter;
-	unsigned twi_cwgr_reg;
-	struct at91_twi_pdata *pdata;
-	bool use_dma;
-	bool use_alt_cmd;
-	bool recv_len_abort;
-	u32 fifo_size;
-	struct at91_twi_dma dma;
-};
-
-static unsigned at91_twi_read(struct at91_twi_dev *dev, unsigned reg)
-{
-	return readl_relaxed(dev->base + reg);
-}
-
-static void at91_twi_write(struct at91_twi_dev *dev, unsigned reg, unsigned val)
-{
-	writel_relaxed(val, dev->base + reg);
-}
-
-static void at91_disable_twi_interrupts(struct at91_twi_dev *dev)
-{
-	at91_twi_write(dev, AT91_TWI_IDR, AT91_TWI_INT_MASK);
-}
-
-static void at91_twi_irq_save(struct at91_twi_dev *dev)
-{
-	dev->imr = at91_twi_read(dev, AT91_TWI_IMR) & AT91_TWI_INT_MASK;
-	at91_disable_twi_interrupts(dev);
-}
-
-static void at91_twi_irq_restore(struct at91_twi_dev *dev)
-{
-	at91_twi_write(dev, AT91_TWI_IER, dev->imr);
-}
-
-static void at91_init_twi_bus_master(struct at91_twi_dev *dev)
-{
-	/* FIFO should be enabled immediately after the software reset */
-	if (dev->fifo_size)
-		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_FIFOEN);
-	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_MSEN);
-	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SVDIS);
-	at91_twi_write(dev, AT91_TWI_CWGR, dev->twi_cwgr_reg);
-}
-
-static void at91_init_twi_bus(struct at91_twi_dev *dev)
-{
-	at91_disable_twi_interrupts(dev);
-	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SWRST);
-
-	at91_init_twi_bus_master(dev);
-}
-
-/*
- * Calculate symmetric clock as stated in datasheet:
- * twi_clk = F_MAIN / (2 * (cdiv * (1 << ckdiv) + offset))
- */
-static void at91_calc_twi_clock(struct at91_twi_dev *dev, int twi_clk)
-{
-	int ckdiv, cdiv, div, hold = 0;
-	struct at91_twi_pdata *pdata = dev->pdata;
-	int offset = pdata->clk_offset;
-	int max_ckdiv = pdata->clk_max_div;
-	u32 twd_hold_time_ns = 0;
-
-	div = max(0, (int)DIV_ROUND_UP(clk_get_rate(dev->clk),
-				       2 * twi_clk) - offset);
-	ckdiv = fls(div >> 8);
-	cdiv = div >> ckdiv;
-
-	if (ckdiv > max_ckdiv) {
-		dev_warn(dev->dev, "%d exceeds ckdiv max value which is %d.\n",
-			 ckdiv, max_ckdiv);
-		ckdiv = max_ckdiv;
-		cdiv = 255;
-	}
-
-	if (pdata->has_hold_field) {
-		of_property_read_u32(dev->dev->of_node, "i2c-sda-hold-time-ns",
-				     &twd_hold_time_ns);
-
-		/*
-		 * hold time = HOLD + 3 x T_peripheral_clock
-		 * Use clk rate in kHz to prevent overflows when computing
-		 * hold.
-		 */
-		hold = DIV_ROUND_UP(twd_hold_time_ns
-				    * (clk_get_rate(dev->clk) / 1000), 1000000);
-		hold -= 3;
-		if (hold < 0)
-			hold = 0;
-		if (hold > AT91_TWI_CWGR_HOLD_MAX) {
-			dev_warn(dev->dev,
-				 "HOLD field set to its maximum value (%d instead of %d)\n",
-				 AT91_TWI_CWGR_HOLD_MAX, hold);
-			hold = AT91_TWI_CWGR_HOLD_MAX;
-		}
-	}
-
-	dev->twi_cwgr_reg = (ckdiv << 16) | (cdiv << 8) | cdiv
-			    | AT91_TWI_CWGR_HOLD(hold);
-
-	dev_dbg(dev->dev, "cdiv %d ckdiv %d hold %d (%d ns)\n",
-		cdiv, ckdiv, hold, twd_hold_time_ns);
-}
-
-static void at91_twi_dma_cleanup(struct at91_twi_dev *dev)
-{
-	struct at91_twi_dma *dma = &dev->dma;
-
-	at91_twi_irq_save(dev);
-
-	if (dma->xfer_in_progress) {
-		if (dma->direction == DMA_FROM_DEVICE)
-			dmaengine_terminate_all(dma->chan_rx);
-		else
-			dmaengine_terminate_all(dma->chan_tx);
-		dma->xfer_in_progress = false;
-	}
-	if (dma->buf_mapped) {
-		dma_unmap_single(dev->dev, sg_dma_address(&dma->sg[0]),
-				 dev->buf_len, dma->direction);
-		dma->buf_mapped = false;
-	}
-
-	at91_twi_irq_restore(dev);
-}
-
-static void at91_twi_write_next_byte(struct at91_twi_dev *dev)
-{
-	if (!dev->buf_len)
-		return;
-
-	/* 8bit write works with and without FIFO */
-	writeb_relaxed(*dev->buf, dev->base + AT91_TWI_THR);
-
-	/* send stop when last byte has been written */
-	if (--dev->buf_len == 0)
-		if (!dev->use_alt_cmd)
-			at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
-
-	dev_dbg(dev->dev, "wrote 0x%x, to go %zu\n", *dev->buf, dev->buf_len);
-
-	++dev->buf;
-}
-
-static void at91_twi_write_data_dma_callback(void *data)
-{
-	struct at91_twi_dev *dev = (struct at91_twi_dev *)data;
-
-	dma_unmap_single(dev->dev, sg_dma_address(&dev->dma.sg[0]),
-			 dev->buf_len, DMA_TO_DEVICE);
-
-	/*
-	 * When this callback is called, THR/TX FIFO is likely not to be empty
-	 * yet. So we have to wait for TXCOMP or NACK bits to be set into the
-	 * Status Register to be sure that the STOP bit has been sent and the
-	 * transfer is completed. The NACK interrupt has already been enabled,
-	 * we just have to enable TXCOMP one.
-	 */
-	at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_TXCOMP);
-	if (!dev->use_alt_cmd)
-		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
-}
-
-static void at91_twi_write_data_dma(struct at91_twi_dev *dev)
-{
-	dma_addr_t dma_addr;
-	struct dma_async_tx_descriptor *txdesc;
-	struct at91_twi_dma *dma = &dev->dma;
-	struct dma_chan *chan_tx = dma->chan_tx;
-	unsigned int sg_len = 1;
-
-	if (!dev->buf_len)
-		return;
-
-	dma->direction = DMA_TO_DEVICE;
-
-	at91_twi_irq_save(dev);
-	dma_addr = dma_map_single(dev->dev, dev->buf, dev->buf_len,
-				  DMA_TO_DEVICE);
-	if (dma_mapping_error(dev->dev, dma_addr)) {
-		dev_err(dev->dev, "dma map failed\n");
-		return;
-	}
-	dma->buf_mapped = true;
-	at91_twi_irq_restore(dev);
-
-	if (dev->fifo_size) {
-		size_t part1_len, part2_len;
-		struct scatterlist *sg;
-		unsigned fifo_mr;
-
-		sg_len = 0;
-
-		part1_len = dev->buf_len & ~0x3;
-		if (part1_len) {
-			sg = &dma->sg[sg_len++];
-			sg_dma_len(sg) = part1_len;
-			sg_dma_address(sg) = dma_addr;
-		}
-
-		part2_len = dev->buf_len & 0x3;
-		if (part2_len) {
-			sg = &dma->sg[sg_len++];
-			sg_dma_len(sg) = part2_len;
-			sg_dma_address(sg) = dma_addr + part1_len;
-		}
-
-		/*
-		 * DMA controller is triggered when at least 4 data can be
-		 * written into the TX FIFO
-		 */
-		fifo_mr = at91_twi_read(dev, AT91_TWI_FMR);
-		fifo_mr &= ~AT91_TWI_FMR_TXRDYM_MASK;
-		fifo_mr |= AT91_TWI_FMR_TXRDYM(AT91_TWI_FOUR_DATA);
-		at91_twi_write(dev, AT91_TWI_FMR, fifo_mr);
-	} else {
-		sg_dma_len(&dma->sg[0]) = dev->buf_len;
-		sg_dma_address(&dma->sg[0]) = dma_addr;
-	}
-
-	txdesc = dmaengine_prep_slave_sg(chan_tx, dma->sg, sg_len,
-					 DMA_MEM_TO_DEV,
-					 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
-	if (!txdesc) {
-		dev_err(dev->dev, "dma prep slave sg failed\n");
-		goto error;
-	}
-
-	txdesc->callback = at91_twi_write_data_dma_callback;
-	txdesc->callback_param = dev;
-
-	dma->xfer_in_progress = true;
-	dmaengine_submit(txdesc);
-	dma_async_issue_pending(chan_tx);
-
-	return;
-
-error:
-	at91_twi_dma_cleanup(dev);
-}
-
-static void at91_twi_read_next_byte(struct at91_twi_dev *dev)
-{
-	/*
-	 * If we are in this case, it means there is garbage data in RHR, so
-	 * delete them.
-	 */
-	if (!dev->buf_len) {
-		at91_twi_read(dev, AT91_TWI_RHR);
-		return;
-	}
-
-	/* 8bit read works with and without FIFO */
-	*dev->buf = readb_relaxed(dev->base + AT91_TWI_RHR);
-	--dev->buf_len;
-
-	/* return if aborting, we only needed to read RHR to clear RXRDY*/
-	if (dev->recv_len_abort)
-		return;
-
-	/* handle I2C_SMBUS_BLOCK_DATA */
-	if (unlikely(dev->msg->flags & I2C_M_RECV_LEN)) {
-		/* ensure length byte is a valid value */
-		if (*dev->buf <= I2C_SMBUS_BLOCK_MAX && *dev->buf > 0) {
-			dev->msg->flags &= ~I2C_M_RECV_LEN;
-			dev->buf_len += *dev->buf;
-			dev->msg->len = dev->buf_len + 1;
-			dev_dbg(dev->dev, "received block length %zu\n",
-					 dev->buf_len);
-		} else {
-			/* abort and send the stop by reading one more byte */
-			dev->recv_len_abort = true;
-			dev->buf_len = 1;
-		}
-	}
-
-	/* send stop if second but last byte has been read */
-	if (!dev->use_alt_cmd && dev->buf_len == 1)
-		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
-
-	dev_dbg(dev->dev, "read 0x%x, to go %zu\n", *dev->buf, dev->buf_len);
-
-	++dev->buf;
-}
-
-static void at91_twi_read_data_dma_callback(void *data)
-{
-	struct at91_twi_dev *dev = (struct at91_twi_dev *)data;
-	unsigned ier = AT91_TWI_TXCOMP;
-
-	dma_unmap_single(dev->dev, sg_dma_address(&dev->dma.sg[0]),
-			 dev->buf_len, DMA_FROM_DEVICE);
-
-	if (!dev->use_alt_cmd) {
-		/* The last two bytes have to be read without using dma */
-		dev->buf += dev->buf_len - 2;
-		dev->buf_len = 2;
-		ier |= AT91_TWI_RXRDY;
-	}
-	at91_twi_write(dev, AT91_TWI_IER, ier);
-}
-
-static void at91_twi_read_data_dma(struct at91_twi_dev *dev)
-{
-	dma_addr_t dma_addr;
-	struct dma_async_tx_descriptor *rxdesc;
-	struct at91_twi_dma *dma = &dev->dma;
-	struct dma_chan *chan_rx = dma->chan_rx;
-	size_t buf_len;
-
-	buf_len = (dev->use_alt_cmd) ? dev->buf_len : dev->buf_len - 2;
-	dma->direction = DMA_FROM_DEVICE;
-
-	/* Keep in mind that we won't use dma to read the last two bytes */
-	at91_twi_irq_save(dev);
-	dma_addr = dma_map_single(dev->dev, dev->buf, buf_len, DMA_FROM_DEVICE);
-	if (dma_mapping_error(dev->dev, dma_addr)) {
-		dev_err(dev->dev, "dma map failed\n");
-		return;
-	}
-	dma->buf_mapped = true;
-	at91_twi_irq_restore(dev);
-
-	if (dev->fifo_size && IS_ALIGNED(buf_len, 4)) {
-		unsigned fifo_mr;
-
-		/*
-		 * DMA controller is triggered when at least 4 data can be
-		 * read from the RX FIFO
-		 */
-		fifo_mr = at91_twi_read(dev, AT91_TWI_FMR);
-		fifo_mr &= ~AT91_TWI_FMR_RXRDYM_MASK;
-		fifo_mr |= AT91_TWI_FMR_RXRDYM(AT91_TWI_FOUR_DATA);
-		at91_twi_write(dev, AT91_TWI_FMR, fifo_mr);
-	}
-
-	sg_dma_len(&dma->sg[0]) = buf_len;
-	sg_dma_address(&dma->sg[0]) = dma_addr;
-
-	rxdesc = dmaengine_prep_slave_sg(chan_rx, dma->sg, 1, DMA_DEV_TO_MEM,
-					 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
-	if (!rxdesc) {
-		dev_err(dev->dev, "dma prep slave sg failed\n");
-		goto error;
-	}
-
-	rxdesc->callback = at91_twi_read_data_dma_callback;
-	rxdesc->callback_param = dev;
-
-	dma->xfer_in_progress = true;
-	dmaengine_submit(rxdesc);
-	dma_async_issue_pending(dma->chan_rx);
-
-	return;
-
-error:
-	at91_twi_dma_cleanup(dev);
-}
-
-static irqreturn_t atmel_twi_interrupt(int irq, void *dev_id)
-{
-	struct at91_twi_dev *dev = dev_id;
-	const unsigned status = at91_twi_read(dev, AT91_TWI_SR);
-	const unsigned irqstatus = status & at91_twi_read(dev, AT91_TWI_IMR);
-
-	if (!irqstatus)
-		return IRQ_NONE;
-	/*
-	 * In reception, the behavior of the twi device (before sama5d2) is
-	 * weird. There is some magic about RXRDY flag! When a data has been
-	 * almost received, the reception of a new one is anticipated if there
-	 * is no stop command to send. That is the reason why ask for sending
-	 * the stop command not on the last data but on the second last one.
-	 *
-	 * Unfortunately, we could still have the RXRDY flag set even if the
-	 * transfer is done and we have read the last data. It might happen
-	 * when the i2c slave device sends too quickly data after receiving the
-	 * ack from the master. The data has been almost received before having
-	 * the order to send stop. In this case, sending the stop command could
-	 * cause a RXRDY interrupt with a TXCOMP one. It is better to manage
-	 * the RXRDY interrupt first in order to not keep garbage data in the
-	 * Receive Holding Register for the next transfer.
-	 */
-	if (irqstatus & AT91_TWI_RXRDY)
-		at91_twi_read_next_byte(dev);
-
-	/*
-	 * When a NACK condition is detected, the I2C controller sets the NACK,
-	 * TXCOMP and TXRDY bits all together in the Status Register (SR).
-	 *
-	 * 1 - Handling NACK errors with CPU write transfer.
-	 *
-	 * In such case, we should not write the next byte into the Transmit
-	 * Holding Register (THR) otherwise the I2C controller would start a new
-	 * transfer and the I2C slave is likely to reply by another NACK.
-	 *
-	 * 2 - Handling NACK errors with DMA write transfer.
-	 *
-	 * By setting the TXRDY bit in the SR, the I2C controller also triggers
-	 * the DMA controller to write the next data into the THR. Then the
-	 * result depends on the hardware version of the I2C controller.
-	 *
-	 * 2a - Without support of the Alternative Command mode.
-	 *
-	 * This is the worst case: the DMA controller is triggered to write the
-	 * next data into the THR, hence starting a new transfer: the I2C slave
-	 * is likely to reply by another NACK.
-	 * Concurrently, this interrupt handler is likely to be called to manage
-	 * the first NACK before the I2C controller detects the second NACK and
-	 * sets once again the NACK bit into the SR.
-	 * When handling the first NACK, this interrupt handler disables the I2C
-	 * controller interruptions, especially the NACK interrupt.
-	 * Hence, the NACK bit is pending into the SR. This is why we should
-	 * read the SR to clear all pending interrupts at the beginning of
-	 * at91_do_twi_transfer() before actually starting a new transfer.
-	 *
-	 * 2b - With support of the Alternative Command mode.
-	 *
-	 * When a NACK condition is detected, the I2C controller also locks the
-	 * THR (and sets the LOCK bit in the SR): even though the DMA controller
-	 * is triggered by the TXRDY bit to write the next data into the THR,
-	 * this data actually won't go on the I2C bus hence a second NACK is not
-	 * generated.
-	 */
-	if (irqstatus & (AT91_TWI_TXCOMP | AT91_TWI_NACK)) {
-		at91_disable_twi_interrupts(dev);
-		complete(&dev->cmd_complete);
-	} else if (irqstatus & AT91_TWI_TXRDY) {
-		at91_twi_write_next_byte(dev);
-	}
-
-	/* catch error flags */
-	dev->transfer_status |= status;
-
-	return IRQ_HANDLED;
-}
-
-static int at91_do_twi_transfer(struct at91_twi_dev *dev)
-{
-	int ret;
-	unsigned long time_left;
-	bool has_unre_flag = dev->pdata->has_unre_flag;
-	bool has_alt_cmd = dev->pdata->has_alt_cmd;
-
-	/*
-	 * WARNING: the TXCOMP bit in the Status Register is NOT a clear on
-	 * read flag but shows the state of the transmission at the time the
-	 * Status Register is read. According to the programmer datasheet,
-	 * TXCOMP is set when both holding register and internal shifter are
-	 * empty and STOP condition has been sent.
-	 * Consequently, we should enable NACK interrupt rather than TXCOMP to
-	 * detect transmission failure.
-	 * Indeed let's take the case of an i2c write command using DMA.
-	 * Whenever the slave doesn't acknowledge a byte, the LOCK, NACK and
-	 * TXCOMP bits are set together into the Status Register.
-	 * LOCK is a clear on write bit, which is set to prevent the DMA
-	 * controller from sending new data on the i2c bus after a NACK
-	 * condition has happened. Once locked, this i2c peripheral stops
-	 * triggering the DMA controller for new data but it is more than
-	 * likely that a new DMA transaction is already in progress, writing
-	 * into the Transmit Holding Register. Since the peripheral is locked,
-	 * these new data won't be sent to the i2c bus but they will remain
-	 * into the Transmit Holding Register, so TXCOMP bit is cleared.
-	 * Then when the interrupt handler is called, the Status Register is
-	 * read: the TXCOMP bit is clear but NACK bit is still set. The driver
-	 * manage the error properly, without waiting for timeout.
-	 * This case can be reproduced easyly when writing into an at24 eeprom.
-	 *
-	 * Besides, the TXCOMP bit is already set before the i2c transaction
-	 * has been started. For read transactions, this bit is cleared when
-	 * writing the START bit into the Control Register. So the
-	 * corresponding interrupt can safely be enabled just after.
-	 * However for write transactions managed by the CPU, we first write
-	 * into THR, so TXCOMP is cleared. Then we can safely enable TXCOMP
-	 * interrupt. If TXCOMP interrupt were enabled before writing into THR,
-	 * the interrupt handler would be called immediately and the i2c command
-	 * would be reported as completed.
-	 * Also when a write transaction is managed by the DMA controller,
-	 * enabling the TXCOMP interrupt in this function may lead to a race
-	 * condition since we don't know whether the TXCOMP interrupt is enabled
-	 * before or after the DMA has started to write into THR. So the TXCOMP
-	 * interrupt is enabled later by at91_twi_write_data_dma_callback().
-	 * Immediately after in that DMA callback, if the alternative command
-	 * mode is not used, we still need to send the STOP condition manually
-	 * writing the corresponding bit into the Control Register.
-	 */
-
-	dev_dbg(dev->dev, "transfer: %s %zu bytes.\n",
-		(dev->msg->flags & I2C_M_RD) ? "read" : "write", dev->buf_len);
-
-	reinit_completion(&dev->cmd_complete);
-	dev->transfer_status = 0;
-
-	/* Clear pending interrupts, such as NACK. */
-	at91_twi_read(dev, AT91_TWI_SR);
-
-	if (dev->fifo_size) {
-		unsigned fifo_mr = at91_twi_read(dev, AT91_TWI_FMR);
-
-		/* Reset FIFO mode register */
-		fifo_mr &= ~(AT91_TWI_FMR_TXRDYM_MASK |
-			     AT91_TWI_FMR_RXRDYM_MASK);
-		fifo_mr |= AT91_TWI_FMR_TXRDYM(AT91_TWI_ONE_DATA);
-		fifo_mr |= AT91_TWI_FMR_RXRDYM(AT91_TWI_ONE_DATA);
-		at91_twi_write(dev, AT91_TWI_FMR, fifo_mr);
-
-		/* Flush FIFOs */
-		at91_twi_write(dev, AT91_TWI_CR,
-			       AT91_TWI_THRCLR | AT91_TWI_RHRCLR);
-	}
-
-	if (!dev->buf_len) {
-		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_QUICK);
-		at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_TXCOMP);
-	} else if (dev->msg->flags & I2C_M_RD) {
-		unsigned start_flags = AT91_TWI_START;
-
-		/* if only one byte is to be read, immediately stop transfer */
-		if (!dev->use_alt_cmd && dev->buf_len <= 1 &&
-		    !(dev->msg->flags & I2C_M_RECV_LEN))
-			start_flags |= AT91_TWI_STOP;
-		at91_twi_write(dev, AT91_TWI_CR, start_flags);
-		/*
-		 * When using dma without alternative command mode, the last
-		 * byte has to be read manually in order to not send the stop
-		 * command too late and then to receive extra data.
-		 * In practice, there are some issues if you use the dma to
-		 * read n-1 bytes because of latency.
-		 * Reading n-2 bytes with dma and the two last ones manually
-		 * seems to be the best solution.
-		 */
-		if (dev->use_dma && (dev->buf_len > AT91_I2C_DMA_THRESHOLD)) {
-			at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_NACK);
-			at91_twi_read_data_dma(dev);
-		} else {
-			at91_twi_write(dev, AT91_TWI_IER,
-				       AT91_TWI_TXCOMP |
-				       AT91_TWI_NACK |
-				       AT91_TWI_RXRDY);
-		}
-	} else {
-		if (dev->use_dma && (dev->buf_len > AT91_I2C_DMA_THRESHOLD)) {
-			at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_NACK);
-			at91_twi_write_data_dma(dev);
-		} else {
-			at91_twi_write_next_byte(dev);
-			at91_twi_write(dev, AT91_TWI_IER,
-				       AT91_TWI_TXCOMP |
-				       AT91_TWI_NACK |
-				       AT91_TWI_TXRDY);
-		}
-	}
-
-	time_left = wait_for_completion_timeout(&dev->cmd_complete,
-					      dev->adapter.timeout);
-	if (time_left == 0) {
-		dev->transfer_status |= at91_twi_read(dev, AT91_TWI_SR);
-		dev_err(dev->dev, "controller timed out\n");
-		at91_init_twi_bus(dev);
-		ret = -ETIMEDOUT;
-		goto error;
-	}
-	if (dev->transfer_status & AT91_TWI_NACK) {
-		dev_dbg(dev->dev, "received nack\n");
-		ret = -EREMOTEIO;
-		goto error;
-	}
-	if (dev->transfer_status & AT91_TWI_OVRE) {
-		dev_err(dev->dev, "overrun while reading\n");
-		ret = -EIO;
-		goto error;
-	}
-	if (has_unre_flag && dev->transfer_status & AT91_TWI_UNRE) {
-		dev_err(dev->dev, "underrun while writing\n");
-		ret = -EIO;
-		goto error;
-	}
-	if ((has_alt_cmd || dev->fifo_size) &&
-	    (dev->transfer_status & AT91_TWI_LOCK)) {
-		dev_err(dev->dev, "tx locked\n");
-		ret = -EIO;
-		goto error;
-	}
-	if (dev->recv_len_abort) {
-		dev_err(dev->dev, "invalid smbus block length recvd\n");
-		ret = -EPROTO;
-		goto error;
-	}
-
-	dev_dbg(dev->dev, "transfer complete\n");
-
-	return 0;
-
-error:
-	/* first stop DMA transfer if still in progress */
-	at91_twi_dma_cleanup(dev);
-	/* then flush THR/FIFO and unlock TX if locked */
-	if ((has_alt_cmd || dev->fifo_size) &&
-	    (dev->transfer_status & AT91_TWI_LOCK)) {
-		dev_dbg(dev->dev, "unlock tx\n");
-		at91_twi_write(dev, AT91_TWI_CR,
-			       AT91_TWI_THRCLR | AT91_TWI_LOCKCLR);
-	}
-	return ret;
-}
-
-static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num)
-{
-	struct at91_twi_dev *dev = i2c_get_adapdata(adap);
-	int ret;
-	unsigned int_addr_flag = 0;
-	struct i2c_msg *m_start = msg;
-	bool is_read;
-
-	dev_dbg(&adap->dev, "at91_xfer: processing %d messages:\n", num);
-
-	ret = pm_runtime_get_sync(dev->dev);
-	if (ret < 0)
-		goto out;
-
-	if (num == 2) {
-		int internal_address = 0;
-		int i;
-
-		/* 1st msg is put into the internal address, start with 2nd */
-		m_start = &msg[1];
-		for (i = 0; i < msg->len; ++i) {
-			const unsigned addr = msg->buf[msg->len - 1 - i];
-
-			internal_address |= addr << (8 * i);
-			int_addr_flag += AT91_TWI_IADRSZ_1;
-		}
-		at91_twi_write(dev, AT91_TWI_IADR, internal_address);
-	}
-
-	dev->use_alt_cmd = false;
-	is_read = (m_start->flags & I2C_M_RD);
-	if (dev->pdata->has_alt_cmd) {
-		if (m_start->len > 0 &&
-		    m_start->len < AT91_I2C_MAX_ALT_CMD_DATA_SIZE) {
-			at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_ACMEN);
-			at91_twi_write(dev, AT91_TWI_ACR,
-				       AT91_TWI_ACR_DATAL(m_start->len) |
-				       ((is_read) ? AT91_TWI_ACR_DIR : 0));
-			dev->use_alt_cmd = true;
-		} else {
-			at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_ACMDIS);
-		}
-	}
-
-	at91_twi_write(dev, AT91_TWI_MMR,
-		       (m_start->addr << 16) |
-		       int_addr_flag |
-		       ((!dev->use_alt_cmd && is_read) ? AT91_TWI_MREAD : 0));
-
-	dev->buf_len = m_start->len;
-	dev->buf = m_start->buf;
-	dev->msg = m_start;
-	dev->recv_len_abort = false;
-
-	ret = at91_do_twi_transfer(dev);
-
-	ret = (ret < 0) ? ret : num;
-out:
-	pm_runtime_mark_last_busy(dev->dev);
-	pm_runtime_put_autosuspend(dev->dev);
-
-	return ret;
-}
-
-/*
- * The hardware can handle at most two messages concatenated by a
- * repeated start via it's internal address feature.
- */
-static const struct i2c_adapter_quirks at91_twi_quirks = {
-	.flags = I2C_AQ_COMB | I2C_AQ_COMB_WRITE_FIRST | I2C_AQ_COMB_SAME_ADDR,
-	.max_comb_1st_msg_len = 3,
-};
-
-static u32 at91_twi_func(struct i2c_adapter *adapter)
-{
-	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL
-		| I2C_FUNC_SMBUS_READ_BLOCK_DATA;
-}
-
-static const struct i2c_algorithm at91_twi_algorithm = {
-	.master_xfer	= at91_twi_xfer,
-	.functionality	= at91_twi_func,
-};
-
-static struct at91_twi_pdata at91rm9200_config = {
-	.clk_max_div = 5,
-	.clk_offset = 3,
-	.has_unre_flag = true,
-	.has_alt_cmd = false,
-	.has_hold_field = false,
-};
-
-static struct at91_twi_pdata at91sam9261_config = {
-	.clk_max_div = 5,
-	.clk_offset = 4,
-	.has_unre_flag = false,
-	.has_alt_cmd = false,
-	.has_hold_field = false,
-};
-
-static struct at91_twi_pdata at91sam9260_config = {
-	.clk_max_div = 7,
-	.clk_offset = 4,
-	.has_unre_flag = false,
-	.has_alt_cmd = false,
-	.has_hold_field = false,
-};
-
-static struct at91_twi_pdata at91sam9g20_config = {
-	.clk_max_div = 7,
-	.clk_offset = 4,
-	.has_unre_flag = false,
-	.has_alt_cmd = false,
-	.has_hold_field = false,
-};
-
-static struct at91_twi_pdata at91sam9g10_config = {
-	.clk_max_div = 7,
-	.clk_offset = 4,
-	.has_unre_flag = false,
-	.has_alt_cmd = false,
-	.has_hold_field = false,
-};
-
-static const struct platform_device_id at91_twi_devtypes[] = {
-	{
-		.name = "i2c-at91rm9200",
-		.driver_data = (unsigned long) &at91rm9200_config,
-	}, {
-		.name = "i2c-at91sam9261",
-		.driver_data = (unsigned long) &at91sam9261_config,
-	}, {
-		.name = "i2c-at91sam9260",
-		.driver_data = (unsigned long) &at91sam9260_config,
-	}, {
-		.name = "i2c-at91sam9g20",
-		.driver_data = (unsigned long) &at91sam9g20_config,
-	}, {
-		.name = "i2c-at91sam9g10",
-		.driver_data = (unsigned long) &at91sam9g10_config,
-	}, {
-		/* sentinel */
-	}
-};
-
-#if defined(CONFIG_OF)
-static struct at91_twi_pdata at91sam9x5_config = {
-	.clk_max_div = 7,
-	.clk_offset = 4,
-	.has_unre_flag = false,
-	.has_alt_cmd = false,
-	.has_hold_field = false,
-};
-
-static struct at91_twi_pdata sama5d4_config = {
-	.clk_max_div = 7,
-	.clk_offset = 4,
-	.has_unre_flag = false,
-	.has_alt_cmd = false,
-	.has_hold_field = true,
-};
-
-static struct at91_twi_pdata sama5d2_config = {
-	.clk_max_div = 7,
-	.clk_offset = 4,
-	.has_unre_flag = true,
-	.has_alt_cmd = true,
-	.has_hold_field = true,
-};
-
-static const struct of_device_id atmel_twi_dt_ids[] = {
-	{
-		.compatible = "atmel,at91rm9200-i2c",
-		.data = &at91rm9200_config,
-	} , {
-		.compatible = "atmel,at91sam9260-i2c",
-		.data = &at91sam9260_config,
-	} , {
-		.compatible = "atmel,at91sam9261-i2c",
-		.data = &at91sam9261_config,
-	} , {
-		.compatible = "atmel,at91sam9g20-i2c",
-		.data = &at91sam9g20_config,
-	} , {
-		.compatible = "atmel,at91sam9g10-i2c",
-		.data = &at91sam9g10_config,
-	}, {
-		.compatible = "atmel,at91sam9x5-i2c",
-		.data = &at91sam9x5_config,
-	}, {
-		.compatible = "atmel,sama5d4-i2c",
-		.data = &sama5d4_config,
-	}, {
-		.compatible = "atmel,sama5d2-i2c",
-		.data = &sama5d2_config,
-	}, {
-		/* sentinel */
-	}
-};
-MODULE_DEVICE_TABLE(of, atmel_twi_dt_ids);
-#endif
-
-static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr)
-{
-	int ret = 0;
-	struct dma_slave_config slave_config;
-	struct at91_twi_dma *dma = &dev->dma;
-	enum dma_slave_buswidth addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
-
-	/*
-	 * The actual width of the access will be chosen in
-	 * dmaengine_prep_slave_sg():
-	 * for each buffer in the scatter-gather list, if its size is aligned
-	 * to addr_width then addr_width accesses will be performed to transfer
-	 * the buffer. On the other hand, if the buffer size is not aligned to
-	 * addr_width then the buffer is transferred using single byte accesses.
-	 * Please refer to the Atmel eXtended DMA controller driver.
-	 * When FIFOs are used, the TXRDYM threshold can always be set to
-	 * trigger the XDMAC when at least 4 data can be written into the TX
-	 * FIFO, even if single byte accesses are performed.
-	 * However the RXRDYM threshold must be set to fit the access width,
-	 * deduced from buffer length, so the XDMAC is triggered properly to
-	 * read data from the RX FIFO.
-	 */
-	if (dev->fifo_size)
-		addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
-
-	memset(&slave_config, 0, sizeof(slave_config));
-	slave_config.src_addr = (dma_addr_t)phy_addr + AT91_TWI_RHR;
-	slave_config.src_addr_width = addr_width;
-	slave_config.src_maxburst = 1;
-	slave_config.dst_addr = (dma_addr_t)phy_addr + AT91_TWI_THR;
-	slave_config.dst_addr_width = addr_width;
-	slave_config.dst_maxburst = 1;
-	slave_config.device_fc = false;
-
-	dma->chan_tx = dma_request_slave_channel_reason(dev->dev, "tx");
-	if (IS_ERR(dma->chan_tx)) {
-		ret = PTR_ERR(dma->chan_tx);
-		dma->chan_tx = NULL;
-		goto error;
-	}
-
-	dma->chan_rx = dma_request_slave_channel_reason(dev->dev, "rx");
-	if (IS_ERR(dma->chan_rx)) {
-		ret = PTR_ERR(dma->chan_rx);
-		dma->chan_rx = NULL;
-		goto error;
-	}
-
-	slave_config.direction = DMA_MEM_TO_DEV;
-	if (dmaengine_slave_config(dma->chan_tx, &slave_config)) {
-		dev_err(dev->dev, "failed to configure tx channel\n");
-		ret = -EINVAL;
-		goto error;
-	}
-
-	slave_config.direction = DMA_DEV_TO_MEM;
-	if (dmaengine_slave_config(dma->chan_rx, &slave_config)) {
-		dev_err(dev->dev, "failed to configure rx channel\n");
-		ret = -EINVAL;
-		goto error;
-	}
-
-	sg_init_table(dma->sg, 2);
-	dma->buf_mapped = false;
-	dma->xfer_in_progress = false;
-	dev->use_dma = true;
-
-	dev_info(dev->dev, "using %s (tx) and %s (rx) for DMA transfers\n",
-		 dma_chan_name(dma->chan_tx), dma_chan_name(dma->chan_rx));
-
-	return ret;
-
-error:
-	if (ret != -EPROBE_DEFER)
-		dev_info(dev->dev, "can't get DMA channel, continue without DMA support\n");
-	if (dma->chan_rx)
-		dma_release_channel(dma->chan_rx);
-	if (dma->chan_tx)
-		dma_release_channel(dma->chan_tx);
-	return ret;
-}
-
-static struct at91_twi_pdata *at91_twi_get_driver_data(
-					struct platform_device *pdev)
-{
-	if (pdev->dev.of_node) {
-		const struct of_device_id *match;
-		match = of_match_node(atmel_twi_dt_ids, pdev->dev.of_node);
-		if (!match)
-			return NULL;
-		return (struct at91_twi_pdata *)match->data;
-	}
-	return (struct at91_twi_pdata *) platform_get_device_id(pdev)->driver_data;
-}
-
-static int at91_twi_probe_master(struct platform_device *pdev,
-				 u32 phy_addr, struct at91_twi_dev *dev)
-{
-	int rc;
-	u32 bus_clk_rate;
-
-	init_completion(&dev->cmd_complete);
-
-	rc = devm_request_irq(&pdev->dev, dev->irq, atmel_twi_interrupt, 0,
-			      dev_name(dev->dev), dev);
-	if (rc) {
-		dev_err(dev->dev, "Cannot get irq %d: %d\n", dev->irq, rc);
-		return rc;
-	}
-
-	if (dev->dev->of_node) {
-		rc = at91_twi_configure_dma(dev, phy_addr);
-		if (rc == -EPROBE_DEFER)
-			return rc;
-	}
-
-	if (!of_property_read_u32(pdev->dev.of_node, "atmel,fifo-size",
-				  &dev->fifo_size)) {
-		dev_info(dev->dev, "Using FIFO (%u data)\n", dev->fifo_size);
-	}
-
-	rc = of_property_read_u32(dev->dev->of_node, "clock-frequency",
-				  &bus_clk_rate);
-	if (rc)
-		bus_clk_rate = DEFAULT_TWI_CLK_HZ;
-
-	at91_calc_twi_clock(dev, bus_clk_rate);
-
-	dev->adapter.algo = &at91_twi_algorithm;
-	dev->adapter.quirks = &at91_twi_quirks;
-
-	return 0;
-}
-
-static int at91_twi_probe(struct platform_device *pdev)
-{
-	struct at91_twi_dev *dev;
-	struct resource *mem;
-	int rc;
-	u32 phy_addr;
-
-	dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
-	if (!dev)
-		return -ENOMEM;
-
-	dev->dev = &pdev->dev;
-
-	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	if (!mem)
-		return -ENODEV;
-	phy_addr = mem->start;
-
-	dev->pdata = at91_twi_get_driver_data(pdev);
-	if (!dev->pdata)
-		return -ENODEV;
-
-	dev->base = devm_ioremap_resource(&pdev->dev, mem);
-	if (IS_ERR(dev->base))
-		return PTR_ERR(dev->base);
-
-	dev->irq = platform_get_irq(pdev, 0);
-	if (dev->irq < 0)
-		return dev->irq;
-
-	platform_set_drvdata(pdev, dev);
-
-	dev->clk = devm_clk_get(dev->dev, NULL);
-	if (IS_ERR(dev->clk)) {
-		dev_err(dev->dev, "no clock defined\n");
-		return -ENODEV;
-	}
-	rc = clk_prepare_enable(dev->clk);
-	if (rc)
-		return rc;
-
-	snprintf(dev->adapter.name, sizeof(dev->adapter.name), "AT91");
-	i2c_set_adapdata(&dev->adapter, dev);
-	dev->adapter.owner = THIS_MODULE;
-	dev->adapter.class = I2C_CLASS_DEPRECATED;
-	dev->adapter.dev.parent = dev->dev;
-	dev->adapter.nr = pdev->id;
-	dev->adapter.timeout = AT91_I2C_TIMEOUT;
-	dev->adapter.dev.of_node = pdev->dev.of_node;
-
-	rc = at91_twi_probe_master(pdev, phy_addr, dev);
-	if (rc)
-		return rc;
-
-	at91_init_twi_bus(dev);
-
-	pm_runtime_set_autosuspend_delay(dev->dev, AUTOSUSPEND_TIMEOUT);
-	pm_runtime_use_autosuspend(dev->dev);
-	pm_runtime_set_active(dev->dev);
-	pm_runtime_enable(dev->dev);
-
-	rc = i2c_add_numbered_adapter(&dev->adapter);
-	if (rc) {
-		clk_disable_unprepare(dev->clk);
-
-		pm_runtime_disable(dev->dev);
-		pm_runtime_set_suspended(dev->dev);
-
-		return rc;
-	}
-
-	dev_info(dev->dev, "AT91 i2c bus driver (hw version: %#x).\n",
-		 at91_twi_read(dev, AT91_TWI_VER));
-	return 0;
-}
-
-static int at91_twi_remove(struct platform_device *pdev)
-{
-	struct at91_twi_dev *dev = platform_get_drvdata(pdev);
-
-	i2c_del_adapter(&dev->adapter);
-	clk_disable_unprepare(dev->clk);
-
-	pm_runtime_disable(dev->dev);
-	pm_runtime_set_suspended(dev->dev);
-
-	return 0;
-}
-
-#ifdef CONFIG_PM
-
-static int at91_twi_runtime_suspend(struct device *dev)
-{
-	struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);
-
-	clk_disable_unprepare(twi_dev->clk);
-
-	pinctrl_pm_select_sleep_state(dev);
-
-	return 0;
-}
-
-static int at91_twi_runtime_resume(struct device *dev)
-{
-	struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);
-
-	pinctrl_pm_select_default_state(dev);
-
-	return clk_prepare_enable(twi_dev->clk);
-}
-
-static int at91_twi_suspend_noirq(struct device *dev)
-{
-	if (!pm_runtime_status_suspended(dev))
-		at91_twi_runtime_suspend(dev);
-
-	return 0;
-}
-
-static int at91_twi_resume_noirq(struct device *dev)
-{
-	struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);
-	int ret;
-
-	if (!pm_runtime_status_suspended(dev)) {
-		ret = at91_twi_runtime_resume(dev);
-		if (ret)
-			return ret;
-	}
-
-	pm_runtime_mark_last_busy(dev);
-	pm_request_autosuspend(dev);
-
-	at91_init_twi_bus(twi_dev);
-
-	return 0;
-}
-
-static const struct dev_pm_ops at91_twi_pm = {
-	.suspend_noirq	= at91_twi_suspend_noirq,
-	.resume_noirq	= at91_twi_resume_noirq,
-	.runtime_suspend	= at91_twi_runtime_suspend,
-	.runtime_resume		= at91_twi_runtime_resume,
-};
-
-#define at91_twi_pm_ops (&at91_twi_pm)
-#else
-#define at91_twi_pm_ops NULL
-#endif
-
-static struct platform_driver at91_twi_driver = {
-	.probe		= at91_twi_probe,
-	.remove		= at91_twi_remove,
-	.id_table	= at91_twi_devtypes,
-	.driver		= {
-		.name	= "at91_i2c",
-		.of_match_table = of_match_ptr(atmel_twi_dt_ids),
-		.pm	= at91_twi_pm_ops,
-	},
-};
-
-static int __init at91_twi_init(void)
-{
-	return platform_driver_register(&at91_twi_driver);
-}
-
-static void __exit at91_twi_exit(void)
-{
-	platform_driver_unregister(&at91_twi_driver);
-}
-
-subsys_initcall(at91_twi_init);
-module_exit(at91_twi_exit);
-
-MODULE_AUTHOR("Nikolaus Voss <[email protected]>");
-MODULE_DESCRIPTION("I2C (TWI) driver for Atmel AT91");
-MODULE_LICENSE("GPL");
-MODULE_ALIAS("platform:at91_i2c");

drivers/i2c/busses/i2c-at91.h new file +151 -0

new file mode 100644
index 0000000..555b167
@@ -0,0 +1,151 @@
+/*
+ *  i2c Support for Atmel's AT91 Two-Wire Interface (TWI)
+ *
+ *  Copyright (C) 2011 Weinmann Medical GmbH
+ *  Author: Nikolaus Voss <[email protected]>
+ *
+ *  Evolved from original work by:
+ *  Copyright (C) 2004 Rick Bronson
+ *  Converted to 2.6 by Andrew Victor <[email protected]>
+ *
+ *  Borrowed heavily from original work by:
+ *  Copyright (C) 2000 Philip Edelbrock <[email protected]>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ */
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/i2c.h>
+#include <linux/platform_data/dma-atmel.h>
+#include <linux/platform_device.h>
+
+#define DEFAULT_TWI_CLK_HZ		100000		/* max 400 Kbits/s */
+#define AT91_I2C_TIMEOUT	msecs_to_jiffies(100)	/* transfer timeout */
+#define AT91_I2C_DMA_THRESHOLD	8			/* enable DMA if transfer size is bigger than this threshold */
+#define AUTOSUSPEND_TIMEOUT		2000
+#define AT91_I2C_MAX_ALT_CMD_DATA_SIZE	256
+
+/* AT91 TWI register definitions */
+#define	AT91_TWI_CR		0x0000	/* Control Register */
+#define	AT91_TWI_START		BIT(0)	/* Send a Start Condition */
+#define	AT91_TWI_STOP		BIT(1)	/* Send a Stop Condition */
+#define	AT91_TWI_MSEN		BIT(2)	/* Master Transfer Enable */
+#define	AT91_TWI_MSDIS		BIT(3)	/* Master Transfer Disable */
+#define	AT91_TWI_SVEN		BIT(4)	/* Slave Transfer Enable */
+#define	AT91_TWI_SVDIS		BIT(5)	/* Slave Transfer Disable */
+#define	AT91_TWI_QUICK		BIT(6)	/* SMBus quick command */
+#define	AT91_TWI_SWRST		BIT(7)	/* Software Reset */
+#define	AT91_TWI_ACMEN		BIT(16) /* Alternative Command Mode Enable */
+#define	AT91_TWI_ACMDIS		BIT(17) /* Alternative Command Mode Disable */
+#define	AT91_TWI_THRCLR		BIT(24) /* Transmit Holding Register Clear */
+#define	AT91_TWI_RHRCLR		BIT(25) /* Receive Holding Register Clear */
+#define	AT91_TWI_LOCKCLR	BIT(26) /* Lock Clear */
+#define	AT91_TWI_FIFOEN		BIT(28) /* FIFO Enable */
+#define	AT91_TWI_FIFODIS	BIT(29) /* FIFO Disable */
+
+#define	AT91_TWI_MMR		0x0004	/* Master Mode Register */
+#define	AT91_TWI_IADRSZ_1	0x0100	/* Internal Device Address Size */
+#define	AT91_TWI_MREAD		BIT(12)	/* Master Read Direction */
+
+#define	AT91_TWI_IADR		0x000c	/* Internal Address Register */
+
+#define	AT91_TWI_CWGR		0x0010	/* Clock Waveform Generator Reg */
+#define	AT91_TWI_CWGR_HOLD_MAX	0x1f
+#define	AT91_TWI_CWGR_HOLD(x)	(((x) & AT91_TWI_CWGR_HOLD_MAX) << 24)
+
+#define	AT91_TWI_SR		0x0020	/* Status Register */
+#define	AT91_TWI_TXCOMP		BIT(0)	/* Transmission Complete */
+#define	AT91_TWI_RXRDY		BIT(1)	/* Receive Holding Register Ready */
+#define	AT91_TWI_TXRDY		BIT(2)	/* Transmit Holding Register Ready */
+#define	AT91_TWI_OVRE		BIT(6)	/* Overrun Error */
+#define	AT91_TWI_UNRE		BIT(7)	/* Underrun Error */
+#define	AT91_TWI_NACK		BIT(8)	/* Not Acknowledged */
+#define	AT91_TWI_LOCK		BIT(23) /* TWI Lock due to Frame Errors */
+
+#define	AT91_TWI_INT_MASK \
+	(AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY | AT91_TWI_NACK)
+
+#define	AT91_TWI_IER		0x0024	/* Interrupt Enable Register */
+#define	AT91_TWI_IDR		0x0028	/* Interrupt Disable Register */
+#define	AT91_TWI_IMR		0x002c	/* Interrupt Mask Register */
+#define	AT91_TWI_RHR		0x0030	/* Receive Holding Register */
+#define	AT91_TWI_THR		0x0034	/* Transmit Holding Register */
+
+#define	AT91_TWI_ACR		0x0040	/* Alternative Command Register */
+#define	AT91_TWI_ACR_DATAL(len)	((len) & 0xff)
+#define	AT91_TWI_ACR_DIR	BIT(8)
+
+#define	AT91_TWI_FMR		0x0050	/* FIFO Mode Register */
+#define	AT91_TWI_FMR_TXRDYM(mode)	(((mode) & 0x3) << 0)
+#define	AT91_TWI_FMR_TXRDYM_MASK	(0x3 << 0)
+#define	AT91_TWI_FMR_RXRDYM(mode)	(((mode) & 0x3) << 4)
+#define	AT91_TWI_FMR_RXRDYM_MASK	(0x3 << 4)
+#define	AT91_TWI_ONE_DATA	0x0
+#define	AT91_TWI_TWO_DATA	0x1
+#define	AT91_TWI_FOUR_DATA	0x2
+
+#define	AT91_TWI_FLR		0x0054	/* FIFO Level Register */
+
+#define	AT91_TWI_FSR		0x0060	/* FIFO Status Register */
+#define	AT91_TWI_FIER		0x0064	/* FIFO Interrupt Enable Register */
+#define	AT91_TWI_FIDR		0x0068	/* FIFO Interrupt Disable Register */
+#define	AT91_TWI_FIMR		0x006c	/* FIFO Interrupt Mask Register */
+
+#define	AT91_TWI_VER		0x00fc	/* Version Register */
+
+struct at91_twi_pdata {
+	unsigned clk_max_div;
+	unsigned clk_offset;
+	bool has_unre_flag;
+	bool has_alt_cmd;
+	bool has_hold_field;
+	struct at_dma_slave dma_slave;
+};
+
+struct at91_twi_dma {
+	struct dma_chan *chan_rx;
+	struct dma_chan *chan_tx;
+	struct scatterlist sg[2];
+	struct dma_async_tx_descriptor *data_desc;
+	enum dma_data_direction direction;
+	bool buf_mapped;
+	bool xfer_in_progress;
+};
+
+struct at91_twi_dev {
+	struct device *dev;
+	void __iomem *base;
+	struct completion cmd_complete;
+	struct clk *clk;
+	u8 *buf;
+	size_t buf_len;
+	struct i2c_msg *msg;
+	int irq;
+	unsigned imr;
+	unsigned transfer_status;
+	struct i2c_adapter adapter;
+	unsigned twi_cwgr_reg;
+	struct at91_twi_pdata *pdata;
+	bool use_dma;
+	bool use_alt_cmd;
+	bool recv_len_abort;
+	u32 fifo_size;
+	struct at91_twi_dma dma;
+};
+
+unsigned at91_twi_read(struct at91_twi_dev *dev, unsigned reg);
+void at91_twi_write(struct at91_twi_dev *dev, unsigned reg, unsigned val);
+void at91_disable_twi_interrupts(struct at91_twi_dev *dev);
+void at91_twi_irq_save(struct at91_twi_dev *dev);
+void at91_twi_irq_restore(struct at91_twi_dev *dev);
+void at91_init_twi_bus(struct at91_twi_dev *dev);
+
+void at91_init_twi_bus_master(struct at91_twi_dev *dev);
+int at91_twi_probe_master(struct platform_device *pdev, u32 phy_addr,
+			  struct at91_twi_dev *dev);

Signature · 1 line

2.7.4

Slave mode driver is based on the concept of i2c-designware driver.

Signed-off-by Juergen Fitschen <[email protected]>

---
 drivers/i2c/busses/Makefile         |   3 +
 drivers/i2c/busses/i2c-at91-core.c  |  13 +++-
 drivers/i2c/busses/i2c-at91-slave.c | 147 ++++++++++++++++++++++++++++++++++++
 drivers/i2c/busses/i2c-at91.h       |  30 +++++++-
 4 files changed, 189 insertions(+), 4 deletions(-)
 create mode 100644 drivers/i2c/busses/i2c-at91-slave.c

new file mode 100644
index 0000000..4b4808e

drivers/i2c/busses/i2c-at91-slave.c new file +133 -0

@@ -0,0 +1,147 @@
+/*
+ *  i2c slave support for Atmel's AT91 Two-Wire Interface (TWI)
+ *
+ *  Copyright (C) 2017 Juergen Fitschen <[email protected]>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/pm_runtime.h>
+
+#include "i2c-at91.h"
+
+static irqreturn_t atmel_twi_interrupt_slave(int irq, void *dev_id)
+{
+	struct at91_twi_dev *dev = dev_id;
+	const unsigned status = at91_twi_read(dev, AT91_TWI_SR);
+	const unsigned irqstatus = status & at91_twi_read(dev, AT91_TWI_IMR);
+	u8 value;
+
+	if (!irqstatus)
+		return IRQ_NONE;
+
+	/* slave address has been detected on I2C bus */
+	if (irqstatus & AT91_TWI_SVACC) {
+		if (status & AT91_TWI_SVREAD) {
+			i2c_slave_event(dev->slave,
+					I2C_SLAVE_READ_REQUESTED, &value);
+			writeb_relaxed(value, dev->base + AT91_TWI_THR);
+			at91_twi_write(dev, AT91_TWI_IER,
+				       AT91_TWI_TXRDY | AT91_TWI_EOSACC);
+		} else {
+			i2c_slave_event(dev->slave,
+					I2C_SLAVE_WRITE_REQUESTED, &value);
+			at91_twi_write(dev, AT91_TWI_IER,
+				       AT91_TWI_RXRDY | AT91_TWI_EOSACC);
+		}
+		at91_twi_write(dev, AT91_TWI_IDR, AT91_TWI_SVACC);
+	}
+
+	/* byte transmitted to remote master */
+	if (irqstatus & AT91_TWI_TXRDY) {
+		i2c_slave_event(dev->slave, I2C_SLAVE_READ_PROCESSED, &value);
+		writeb_relaxed(value, dev->base + AT91_TWI_THR);
+	}
+
+	/* byte received from remote master */
+	if (irqstatus & AT91_TWI_RXRDY) {
+		value = readb_relaxed(dev->base + AT91_TWI_RHR);
+		i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_RECEIVED, &value);
+	}
+
+	/* master sent stop */
+	if (irqstatus & AT91_TWI_EOSACC) {
+		at91_twi_write(dev, AT91_TWI_IDR,
+			       AT91_TWI_TXRDY | AT91_TWI_RXRDY | AT91_TWI_EOSACC);
+		at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_SVACC);
+		i2c_slave_event(dev->slave, I2C_SLAVE_STOP, &value);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int at91_reg_slave(struct i2c_client *slave)
+{
+	struct at91_twi_dev *dev = i2c_get_adapdata(slave->adapter);
+
+	if (dev->slave)
+		return -EBUSY;
+
+	if (slave->flags & I2C_CLIENT_TEN)
+		return -EAFNOSUPPORT;
+
+	/* Make sure twi_clk doesn't get turned off! */
+	pm_runtime_get_sync(dev->dev);
+
+	dev->slave = slave;
+	dev->smr = AT91_TWI_SMR_SADR(slave->addr);
+
+	at91_init_twi_bus(dev);
+	at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_SVACC);
+
+	dev_info(dev->dev, "entered slave mode (ADR=%d)\n", slave->addr);
+
+	return 0;
+}
+
+static int at91_unreg_slave(struct i2c_client *slave)
+{
+	struct at91_twi_dev *dev = i2c_get_adapdata(slave->adapter);
+
+	WARN_ON(!dev->slave);
+
+	dev_info(dev->dev, "leaving slave mode\n");
+
+	dev->slave = NULL;
+	dev->smr = 0;
+
+	at91_init_twi_bus(dev);
+
+	pm_runtime_put(dev->dev);
+
+	return 0;
+}
+
+static u32 at91_twi_func(struct i2c_adapter *adapter)
+{
+	return I2C_FUNC_SLAVE | I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL
+		| I2C_FUNC_SMBUS_READ_BLOCK_DATA;
+}
+
+static const struct i2c_algorithm at91_twi_algorithm_slave = {
+	.reg_slave	= at91_reg_slave,
+	.unreg_slave	= at91_unreg_slave,
+	.functionality	= at91_twi_func,
+};
+
+int at91_twi_probe_slave(struct platform_device *pdev,
+			 u32 phy_addr, struct at91_twi_dev *dev)
+{
+	int rc;
+
+	rc = devm_request_irq(&pdev->dev, dev->irq, atmel_twi_interrupt_slave,
+			      0, dev_name(dev->dev), dev);
+	if (rc) {
+		dev_err(dev->dev, "Cannot get irq %d: %d\n", dev->irq, rc);
+		return rc;
+	}

drivers/i2c/busses/i2c-at91-slave.c new file +4 -0

+		at91_twi_write(dev, AT91_TWI_SMR, dev->smr);
+		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SVEN);
+	}
+}

drivers/i2c/busses/i2c-at91.h +29 -1

index 555b167..bb502c1 100644
@@ -53,6 +53,10 @@
 #define	AT91_TWI_IADRSZ_1	0x0100	/* Internal Device Address Size */
 #define	AT91_TWI_MREAD		BIT(12)	/* Master Read Direction */
 
+#define	AT91_TWI_SMR		0x0008	/* Slave Mode Register */
+#define	AT91_TWI_SMR_SADR_MAX	0x007f
+#define	AT91_TWI_SMR_SADR(x)	(((x) & AT91_TWI_SMR_SADR_MAX) << 16)
+
 #define	AT91_TWI_IADR		0x000c	/* Internal Address Register */
 
 #define	AT91_TWI_CWGR		0x0010	/* Clock Waveform Generator Reg */

@@ -63,13 +67,17 @@
 #define	AT91_TWI_TXCOMP		BIT(0)	/* Transmission Complete */
 #define	AT91_TWI_RXRDY		BIT(1)	/* Receive Holding Register Ready */
 #define	AT91_TWI_TXRDY		BIT(2)	/* Transmit Holding Register Ready */
+#define	AT91_TWI_SVREAD		BIT(3)	/* Slave Read */
+#define	AT91_TWI_SVACC		BIT(4)	/* Slave Access */
 #define	AT91_TWI_OVRE		BIT(6)	/* Overrun Error */
 #define	AT91_TWI_UNRE		BIT(7)	/* Underrun Error */
 #define	AT91_TWI_NACK		BIT(8)	/* Not Acknowledged */
+#define	AT91_TWI_EOSACC		BIT(11)	/* End Of Slave Access */
 #define	AT91_TWI_LOCK		BIT(23) /* TWI Lock due to Frame Errors */
 
 #define	AT91_TWI_INT_MASK \
-	(AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY | AT91_TWI_NACK)
+	(AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY | AT91_TWI_NACK \
+	| AT91_TWI_SVACC | AT91_TWI_EOSACC)
 
 #define	AT91_TWI_IER		0x0024	/* Interrupt Enable Register */
 #define	AT91_TWI_IDR		0x0028	/* Interrupt Disable Register */

@@ -137,6 +145,11 @@ struct at91_twi_dev {
 	bool recv_len_abort;
 	u32 fifo_size;
 	struct at91_twi_dma dma;
+	bool slave_detected;
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+	unsigned smr;
+	struct i2c_client *slave;
+#endif
 };
 
 unsigned at91_twi_read(struct at91_twi_dev *dev, unsigned reg);

@@ -149,3 +162,18 @@ void at91_init_twi_bus(struct at91_twi_dev *dev);
 void at91_init_twi_bus_master(struct at91_twi_dev *dev);
 int at91_twi_probe_master(struct platform_device *pdev, u32 phy_addr,
 			  struct at91_twi_dev *dev);
+
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+void at91_init_twi_bus_slave(struct at91_twi_dev *dev);
+int at91_twi_probe_slave(struct platform_device *pdev, u32 phy_addr,
+			 struct at91_twi_dev *dev);
+
+#else
+static inline void at91_init_twi_bus_slave(struct at91_twi_dev *dev) {}
+static inline int at91_twi_probe_slave(struct platform_device *pdev,
+				       u32 phy_addr, struct at91_twi_dev *dev)
+{
+	return -EINVAL;
+}
+
+#endif

Signature · 1 line

2.7.4

Quoted 11 lines · Juergen Fitschen

Slave mode driver is based on the concept of i2c-designware driver.

Signed-off-by Juergen Fitschen <[email protected]>

---
 drivers/i2c/busses/Makefile         |   3 +
 drivers/i2c/busses/i2c-at91-core.c  |  13 +++-
 drivers/i2c/busses/i2c-at91-slave.c | 147 ++++++++++++++++++++++++++++++++++++
 drivers/i2c/busses/i2c-at91.h       |  30 +++++++-
 4 files changed, 189 insertions(+), 4 deletions(-)
 create mode 100644 drivers/i2c/busses/i2c-at91-slave.c

Adding an example in Documentation/devicetree/bindings/i2c/i2c-at91.txt could be useful.

drivers/i2c/busses/Makefile obj-$(CONFIG_I2C_ALTERA) += i2c-altera.o · line 39

Quoted 11 lines

drivers/i2c/busses/Makefile +3 -0

index 2a79c3d..b38fb8e9 100644
@@ -34,6 +34,9 @@ obj-$(CONFIG_I2C_ALTERA)	+= i2c-altera.o
 obj-$(CONFIG_I2C_ASPEED)	+= i2c-aspeed.o
 obj-$(CONFIG_I2C_AT91)		+= i2c-at91.o
 i2c-at91-objs			:= i2c-at91-core.o i2c-at91-master.o
+ifeq ($(CONFIG_I2C_SLAVE),y)
+	i2c-at91-objs		+= i2c-at91-slave.o
+endif

As Designware driver, I would add an entry in 'I2C Hardware Bus Support'.

If a user wants to use the I2C GPIO driver as the I2C slave (once it has the slave support), it's not useful to embed i2c-at91-slave code.

drivers/i2c/busses/Makefile obj-$(CONFIG_I2C_ALTERA) += i2c-altera.o

Quoted 4 lines

drivers/i2c/busses/Makefile +4 -0

+void at91_init_twi_bus_slave(struct at91_twi_dev *dev)
+{
+	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_MSDIS);
+	if (dev->slave_detected && dev->smr) {

slave_detected has been checked in the caller. smr has been set just before calling at91_init_twi_bus().

Helle Ludovic,

while going through this patch a question related to the Atmel / Microchip HW came into mind:

drivers/i2c/busses/i2c-at91.h line 80

Quoted 6 lines · Juergen Fitschen

drivers/i2c/busses/i2c-at91.h +2 -1

(...)
 #define	AT91_TWI_INT_MASK \
-	(AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY | AT91_TWI_NACK)
+	(AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY | AT91_TWI_NACK \
+	| AT91_TWI_SVACC | AT91_TWI_EOSACC)

The AT91_TWI_INT_MASK is used to disable all interrputs in the at91_disable_twi_interrupts function by writing the mask to the interrupt disable register (IDR). I wonder what happens on MPUs that don't have AT91_TWI_SVACC and AT91_TWI_EOSACC implemented, like the AT91RM9200? Do you think we should revise this and write specific masks depending on the current moude the I2C HW is in?

Something like this:

void at91_disable_twi_interrupts(struct at91_twi_dev *dev)

{
        if (dev->slave_detected)
                at91_twi_write(dev, AT91_TWI_IDR, AT91_TWI_INT_MASK_SLAVE);
        else
                at91_twi_write(dev, AT91_TWI_IDR, AT91_TWI_INT_MASK_MASTER);
}

Some AT91 hardware has no slave mode included or only limited features (i.e. no fifos).

Signed-off-by Juergen Fitschen <[email protected]>

---
 drivers/i2c/busses/i2c-at91-core.c | 14 ++++++++++++--
 drivers/i2c/busses/i2c-at91.h      |  5 +++++
 2 files changed, 17 insertions(+), 2 deletions(-)

drivers/i2c/busses/i2c-at91-core.c +12 -2

index 3d7287c..9bf1e9d 100644
@@ -69,6 +69,7 @@ void at91_init_twi_bus(struct at91_twi_dev *dev)
 static struct at91_twi_pdata at91rm9200_config = {
 	.clk_max_div = 5,
 	.clk_offset = 3,
+	.slave_mode_features = 0,
 	.has_unre_flag = true,
 	.has_alt_cmd = false,
 	.has_hold_field = false,

@@ -77,6 +78,7 @@ static struct at91_twi_pdata at91rm9200_config = {
 static struct at91_twi_pdata at91sam9261_config = {
 	.clk_max_div = 5,
 	.clk_offset = 4,
+	.slave_mode_features = AT91_TWI_SM_AVAILABLE,
 	.has_unre_flag = false,
 	.has_alt_cmd = false,
 	.has_hold_field = false,

@@ -85,6 +87,7 @@ static struct at91_twi_pdata at91sam9261_config = {
 static struct at91_twi_pdata at91sam9260_config = {
 	.clk_max_div = 7,
 	.clk_offset = 4,
+	.slave_mode_features = AT91_TWI_SM_AVAILABLE,
 	.has_unre_flag = false,
 	.has_alt_cmd = false,
 	.has_hold_field = false,

@@ -93,6 +96,7 @@ static struct at91_twi_pdata at91sam9260_config = {
 static struct at91_twi_pdata at91sam9g20_config = {
 	.clk_max_div = 7,
 	.clk_offset = 4,
+	.slave_mode_features = AT91_TWI_SM_AVAILABLE,
 	.has_unre_flag = false,
 	.has_alt_cmd = false,
 	.has_hold_field = false,

@@ -101,6 +105,7 @@ static struct at91_twi_pdata at91sam9g20_config = {
 static struct at91_twi_pdata at91sam9g10_config = {
 	.clk_max_div = 7,
 	.clk_offset = 4,
+	.slave_mode_features = AT91_TWI_SM_AVAILABLE,
 	.has_unre_flag = false,
 	.has_alt_cmd = false,
 	.has_hold_field = false,

@@ -131,6 +136,7 @@ static const struct platform_device_id at91_twi_devtypes[] = {
 static struct at91_twi_pdata at91sam9x5_config = {
 	.clk_max_div = 7,
 	.clk_offset = 4,
+	.slave_mode_features = AT91_TWI_SM_AVAILABLE,
 	.has_unre_flag = false,
 	.has_alt_cmd = false,
 	.has_hold_field = false,

@@ -139,6 +145,7 @@ static struct at91_twi_pdata at91sam9x5_config = {
 static struct at91_twi_pdata sama5d4_config = {
 	.clk_max_div = 7,
 	.clk_offset = 4,
+	.slave_mode_features = AT91_TWI_SM_AVAILABLE,
 	.has_unre_flag = false,
 	.has_alt_cmd = false,
 	.has_hold_field = true,

@@ -147,6 +154,7 @@ static struct at91_twi_pdata sama5d4_config = {
 static struct at91_twi_pdata sama5d2_config = {
 	.clk_max_div = 7,
 	.clk_offset = 4,
+	.slave_mode_features = AT91_TWI_SM_AVAILABLE | AT91_TWI_SM_HAS_FIFO | AT91_TWI_SM_CAN_NACK,
 	.has_unre_flag = true,
 	.has_alt_cmd = true,
 	.has_hold_field = true,

@@ -219,6 +227,10 @@ static int at91_twi_probe(struct platform_device *pdev)
 	if (!dev->pdata)
 		return -ENODEV;
 
+	dev->slave_detected = i2c_detect_slave_mode(&pdev->dev);
+	if (dev->slave_detected && dev->pdata->slave_mode_features == 0)
+		return -EPFNOSUPPORT;
+
 	dev->base = devm_ioremap_resource(&pdev->dev, mem);
 	if (IS_ERR(dev->base))
 		return PTR_ERR(dev->base);

@@ -245,8 +257,6 @@ static int at91_twi_probe(struct platform_device *pdev)
 	dev->adapter.timeout = AT91_I2C_TIMEOUT;
 	dev->adapter.dev.of_node = pdev->dev.of_node;
 
-	dev->slave_detected = i2c_detect_slave_mode(&pdev->dev);
-
 	if (dev->slave_detected)
 		rc = at91_twi_probe_slave(pdev, phy_addr, dev);
 	else

drivers/i2c/busses/i2c-at91.h +0 -0

index bb502c1..4a4fa67 100644