Add 1-wire master driver for i.MX27 / i.MX31

From: Sascha Hauer <[email protected]>

This patch adds support for the 1-wire master interface for i.MX27 and i.MX31.

Signed-off-by Luotao Fu <[email protected]>

Signed-off-by Sascha Hauer <[email protected]>

Signed-off-by Evgeniy Polyakov <[email protected]>

---
 drivers/w1/masters/Kconfig  |    6 +
 drivers/w1/masters/Makefile |    2 +
 drivers/w1/masters/mxc_w1.c |  215 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 223 insertions(+), 0 deletions(-)
 create mode 100644 drivers/w1/masters/mxc_w1.c

drivers/w1/masters/Kconfig +6 -0

index a14d5b6..f2da1a8 100644
@@ -34,6 +34,12 @@ config W1_MASTER_DS2482
 	  This driver can also be built as a module.  If so, the module
 	  will be called ds2482.
 
+config W1_MASTER_MXC
+	tristate "Freescale MXC 1-wire busmaster"
+	depends on W1 && ARCH_MXC
+	help
+	  Say Y here to enable MXC 1-wire host
+
 config W1_MASTER_DS1WM
 	tristate "Maxim DS1WM 1-wire busmaster"
 	depends on W1 && ARM

drivers/w1/masters/Makefile +2 -0

index bc4714a..c5a3e96 100644
@@ -5,6 +5,8 @@
 obj-$(CONFIG_W1_MASTER_MATROX)		+= matrox_w1.o
 obj-$(CONFIG_W1_MASTER_DS2490)		+= ds2490.o
 obj-$(CONFIG_W1_MASTER_DS2482)		+= ds2482.o
+obj-$(CONFIG_W1_MASTER_MXC)		+= mxc_w1.o
+
 obj-$(CONFIG_W1_MASTER_DS1WM)		+= ds1wm.o
 obj-$(CONFIG_W1_MASTER_GPIO)		+= w1-gpio.o
 obj-$(CONFIG_HDQ_MASTER_OMAP)		+= omap_hdq.o

drivers/w1/masters/mxc_w1.c new file +215 -0

new file mode 100644
index 0000000..92323be
@@ -0,0 +1,215 @@
+/*
+ * Copyright 2005-2008 Freescale Semiconductor, Inc. All Rights Reserved.
+ * Copyright 2008 Luotao Fu, [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.
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+
+#include "../w1.h"
+#include "../w1_int.h"
+#include "../w1_log.h"
+
+/* According to the mx27 Datasheet the reset procedure should take up to about
+ * 1350us. We set the timeout to 500*100us = 50ms for sure */
+#define MXC_W1_RESET_TIMEOUT 500
+
+/*
+ * MXC W1 Register offsets
+ */
+#define MXC_W1_CONTROL          0x00
+#define MXC_W1_TIME_DIVIDER     0x02
+#define MXC_W1_RESET            0x04
+#define MXC_W1_COMMAND          0x06
+#define MXC_W1_TXRX             0x08
+#define MXC_W1_INTERRUPT        0x0A
+#define MXC_W1_INTERRUPT_EN     0x0C
+
+struct mxc_w1_device {
+	void __iomem *regs;
+	unsigned int clkdiv;
+	struct clk *clk;
+	struct w1_bus_master *bus_master;
+};
+
+/*
+ * this is the low level routine to
+ * reset the device on the One Wire interface
+ * on the hardware
+ */
+static u8 mxc_w1_ds2_reset_bus(void *data)
+{
+	u8 reg_val, rc = 1;
+	unsigned int timeout_cnt = 0;
+
+	struct mxc_w1_device *dev = (struct mxc_w1_device *)data;
+
+	__raw_writeb(0x80, (dev->regs + MXC_W1_CONTROL));
+
+	while (1) {
+		reg_val = __raw_readb(dev->regs + MXC_W1_CONTROL);
+
+		if (((reg_val >> 7) & 0x1) == 0 ||
+		    timeout_cnt > MXC_W1_RESET_TIMEOUT) {
+			rc = 0;
+			break;
+		} else
+			timeout_cnt++;
+
+		udelay(100);
+	}
+	return (reg_val >> 7) & 0x1;
+}
+
+/*
+ * this is the low level routine to read/write a bit on the One Wire
+ * interface on the hardware. It does write 0 if parameter bit is set
+ * to 0, otherwise a write 1/read.
+ */
+static u8 mxc_w1_ds2_touch_bit(void *data, u8 bit)
+{
+	unsigned int timeout_cnt = 400;
+
+	struct mxc_w1_device *mdev = (struct mxc_w1_device *)data;
+	void __iomem *ctrl_addr = mdev->regs + MXC_W1_CONTROL;
+
+	__raw_writeb((1 << (5 - bit)), ctrl_addr);
+
+	while (timeout_cnt--) {
+		if (!((__raw_readb(ctrl_addr) >> (5 - bit)) & 0x1))
+			break;
+
+		udelay(1);
+	}
+
+	return ((__raw_readb(ctrl_addr)) >> 3) & 0x1;
+}
+
+static int __devinit mxc_w1_probe(struct platform_device *pdev)
+{
+	struct mxc_w1_device *mdev;
+	struct resource *res;
+	int err = 0;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+
+	mdev = kzalloc(sizeof(struct mxc_w1_device) +
+		      sizeof(struct w1_bus_master), GFP_KERNEL);
+
+	if (!mdev)
+		return -ENOMEM;
+
+	mdev->clk = clk_get(&pdev->dev, "owire_clk");
+	if (!mdev->clk) {
+		err = -ENODEV;
+		goto failed_clk;
+	}
+
+	mdev->bus_master = (struct w1_bus_master *)(mdev + 1);
+	mdev->clkdiv = (clk_get_rate(mdev->clk) / 1000000) - 1;
+
+	res = request_mem_region(res->start, resource_size(res),
+				"mxc_w1");
+	if (!res) {
+		err = -EBUSY;
+		goto failed_req;
+	}
+
+	mdev->regs = ioremap(res->start, resource_size(res)); 
+	if (!mdev->regs) {
+		printk(KERN_ERR"Cannot map frame buffer registers\n");
+		goto failed_ioremap;
+	}
+
+	clk_enable(mdev->clk);
+	__raw_writeb(mdev->clkdiv, mdev->regs + MXC_W1_TIME_DIVIDER);
+
+	mdev->bus_master->data = mdev;
+	mdev->bus_master->reset_bus = &mxc_w1_ds2_reset_bus;
+	mdev->bus_master->touch_bit = &mxc_w1_ds2_touch_bit;
+
+	err = w1_add_master_device(mdev->bus_master);
+
+	if (err)
+		goto failed_add;
+
+	platform_set_drvdata(pdev, mdev);
+	return 0;
+
+failed_add:
+	iounmap(mdev->regs);
+failed_ioremap:
+	release_mem_region(res->start, resource_size(res));
+failed_req:
+	clk_put(mdev->clk);
+failed_clk:
+	kfree(mdev);
+	return err;
+}
+
+/*
+ * disassociate the w1 device from the driver
+ */
+static int mxc_w1_remove(struct platform_device *pdev)
+{
+	struct mxc_w1_device *mdev = platform_get_drvdata(pdev);
+	struct resource *res;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+	w1_remove_master_device(mdev->bus_master);
+
+	iounmap(mdev->regs);
+	release_mem_region(res->start, resource_size(res));
+	clk_disable(mdev->clk);
+	clk_put(mdev->clk);
+
+	platform_set_drvdata(pdev, NULL);
+
+	return 0;
+}
+
+static struct platform_driver mxc_w1_driver = {
+	.driver = {
+		   .name = "mxc_w1",
+		   },
+	.probe = mxc_w1_probe,
+	.remove = mxc_w1_remove,
+};
+
+static int __init mxc_w1_init(void)
+{
+	return platform_driver_register(&mxc_w1_driver);
+}
+
+static void mxc_w1_exit(void)
+{
+	platform_driver_unregister(&mxc_w1_driver);
+}
+
+module_init(mxc_w1_init);
+module_exit(mxc_w1_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Freescale Semiconductors Inc");
+MODULE_DESCRIPTION("Driver for One-Wire on MXC");

Signature · 1 line

1.5.2.5

From: Sascha Hauer <[email protected]>

This patch adds support for the 1-wire master interface for i.MX27 and i.MX31.

Ack for this one, the other patches from this series need to go via Russell King to prevent merge conflicts with other MX2 patches. Sorry, I should have made that clear.

...

(quoted diff) +2 -0

+static int __devinit mxc_w1_probe(struct platform_device *pdev)
+{

(quoted diff) +28 -0

+	res = request_mem_region(res->start, resource_size(res),
+				"mxc_w1");
+	if (!res) {
+		err = -EBUSY;
+		goto failed_req;
+	}
+
+	mdev->regs = ioremap(res->start, resource_size(res)); 
+	if (!mdev->regs) {
+		printk(KERN_ERR"Cannot map frame buffer registers\n");
+		goto failed_ioremap;
+	}
+
+	clk_enable(mdev->clk);
+	__raw_writeb(mdev->clkdiv, mdev->regs + MXC_W1_TIME_DIVIDER);
+
+	mdev->bus_master->data = mdev;
+	mdev->bus_master->reset_bus = &mxc_w1_ds2_reset_bus;
+	mdev->bus_master->touch_bit = &mxc_w1_ds2_touch_bit;
+
+	err = w1_add_master_device(mdev->bus_master);
+
+	if (err)
+		goto failed_add;
+
+	platform_set_drvdata(pdev, mdev);
+	return 0;
+

Quoted 4 lines · On Wed, 19 Nov 2008 01:16:13 +0300 Evgeniy Polyakov <[email protected]> wrote:

From: Sascha Hauer <[email protected]>

This patch adds support for the 1-wire master interface for i.MX27 and i.MX31.

Looks sane.

Quoted 3 lines

Ack for this one, the other patches from this series need to go via Russell King to prevent merge conflicts with other MX2 patches. Sorry, I should have made that clear.

Is this patch fully independent of the others?

Quoted 6 lines

...

(quoted diff) +2 -0

+static int __devinit mxc_w1_probe(struct platform_device *pdev)
+{

Review

Quoted 10 lines

(quoted diff) +10 -0

+	struct mxc_w1_device *mdev;
+	struct resource *res;
+	int err = 0;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+
+	mdev = kzalloc(sizeof(struct mxc_w1_device) +
+		      sizeof(struct w1_bus_master), GFP_KERNEL);

whee, that's a bit of a hack. It would be better to do

struct foo {
	struct mxc_w1_device mxc_w1_device;
	struct w1_bus_master w1_bus_master;
};

no?

Review

Quoted 12 lines

(quoted diff) +11 -0

+	if (!mdev)
+		return -ENOMEM;
+
+	mdev->clk = clk_get(&pdev->dev, "owire_clk");
+	if (!mdev->clk) {
+		err = -ENODEV;
+		goto failed_clk;
+	}
+
+	mdev->bus_master = (struct w1_bus_master *)(mdev + 1);
+	mdev->clkdiv = (clk_get_rate(mdev->clk) / 1000000) - 1;

If that 1000000 refers to microseconds then the use of USEC_PER_SEC would be clearer.