i3c dw,ast2600: Add a driver for the AST2600 i3c controller

Add a devicetree binding for the ast2600 i3c controller hardware. This is heavily based on the designware i3c core, plus a reset facility and two platform-specific properties:

- sda-pullup-ohms: to specify the value of the configurable pullup resistors on the SDA line

- aspeed,global-regs: to reference the (ast2600-specific) i3c global register block, and the device index to use within it.

Reviewed-by Krzysztof Kozlowski <[email protected]> (on v1)

Signed-off-by Jeremy Kerr <[email protected]>

This series adds a new i3c controller driver, for the ASPEED AST2600 13c SoC peripheral. This device is very similar to the dw i3c controller, so we implement this by adding a little platform abstraction to the dw driver, and then a platform implementation for ast2600.

v2: This is a rework from an earlier series that implemented this as part of the dw driver; I have adopted Ben Dooks' suggestion to split into a new driver + exported hooks from the dw base.

As always: comments, queries etc. are most welcome.

Cheers,

Jeremy

Jeremy Kerr (3):
i3c: dw: Add infrastructure for platform-specific implementations
dt-bindings: i3c: Add AST2600 i3c controller
i3c: ast2600: Add AST2600 platform-specific driver

 .../bindings/i3c/aspeed,ast2600-i3c.yaml      |  72 ++++++++
 MAINTAINERS                                   |   6 +
 drivers/i3c/master/Kconfig                    |  14 ++
 drivers/i3c/master/Makefile                   |   1 +
 drivers/i3c/master/ast2600-i3c-master.c       | 169 ++++++++++++++++++
 drivers/i3c/master/dw-i3c-master.c            |  76 ++++----
 drivers/i3c/master/dw-i3c-master.h            |  55 ++++++
 7 files changed, 360 insertions(+), 33 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/i3c/aspeed,ast2600-i3c.yaml
 create mode 100644 drivers/i3c/master/ast2600-i3c-master.c
 create mode 100644 drivers/i3c/master/dw-i3c-master.h

--
2.39.2

Now that we have platform-specific infrastructure for the dw i3c driver, add platform support for the ASPEED AST2600 SoC.

The AST2600 has a small set of "i3c global" registers, providing platform-level i3c configuration outside of the i3c core.

For the ast2600, we need a couple of extra setup operations:

- on probe: find the i3c global register set and parse the SDA pullup resistor values

- on init: set the pullups accordingly, and set the i3c instance IDs

Signed-off-by Jeremy Kerr <[email protected]>

---
v2:
- use new dw platform infrastructure

---
  MAINTAINERS                             |   6 +
  drivers/i3c/master/Kconfig              |  14 ++
  drivers/i3c/master/Makefile             |   1 +
  drivers/i3c/master/ast2600-i3c-master.c | 169 ++++++++++++++++++++++++
  4 files changed, 190 insertions(+)

create mode 100644 drivers/i3c/master/ast2600-i3c-master.c

MAINTAINERS +6 -0

index bd8ebc25afcf..ecadd5ccf771 100644
@@ -9714,6 +9714,12 @@ S:	Orphan
  F:	Documentation/devicetree/bindings/i3c/snps,dw-i3c-master.yaml
  F:	drivers/i3c/master/dw*
 
+I3C DRIVER FOR ASPEED AST2600
+M:	Jeremy Kerr <[email protected]>
+S:	Maintained
+F:	Documentation/devicetree/bindings/i3c/aspeed,ast2600-i3c.yaml
+F:	drivers/i3c/master/ast2600-i3c-master.c
+
  I3C SUBSYSTEM
  M:	Alexandre Belloni <[email protected]>
  L:	[email protected] (moderated for non-subscribers)

drivers/i3c/master/Kconfig +14 -0

index 3b8f95916f46..90dee3ec5520 100644
@@ -22,6 +22,20 @@ config DW_I3C_MASTER
  	  This driver can also be built as a module.  If so, the module
  	  will be called dw-i3c-master.
 
+config AST2600_I3C_MASTER
+	tristate "ASPEED AST2600 I3C master driver"
+	depends on DW_I3C_MASTER
+	depends on ARCH_ASPEED || COMPILE_TEST
+	select MFD_SYSCON
+	help
+	  Support for ASPEED AST2600 I3C Controller.
+
+	  This hardware is an instance of the DW I3C controller; this
+	  driver adds platform- specific support for AST2600 hardware.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called ast2600-i3c-master.
+
  config SVC_I3C_MASTER
  	tristate "Silvaco I3C Dual-Role Master driver"
  	depends on I3C

drivers/i3c/master/Makefile +1 -0

index b3fee0f690b2..3e97960160bc 100644
@@ -1,5 +1,6 @@
  # SPDX-License-Identifier: GPL-2.0-only
  obj-$(CONFIG_CDNS_I3C_MASTER)		+= i3c-master-cdns.o
  obj-$(CONFIG_DW_I3C_MASTER)		+= dw-i3c-master.o
+obj-$(CONFIG_AST2600_I3C_MASTER)	+= ast2600-i3c-master.o
  obj-$(CONFIG_SVC_I3C_MASTER)		+= svc-i3c-master.o
  obj-$(CONFIG_MIPI_I3C_HCI)		+= mipi-i3c-hci/

drivers/i3c/master/ast2600-i3c-master.c new file +101 -0

new file mode 100644
index 000000000000..d3d7b7d19f22
@@ -0,0 +1,169 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2023 Code Construct
+ *
+ * Author: Jeremy Kerr <[email protected]>
+ */
+
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#include "dw-i3c-master.h"
+
+/* AST2600-specific global register set */
+#define AST2600_I3CG_REG0(idx)	(((idx) * 4 * 4) + 0x10)
+#define AST2600_I3CG_REG1(idx)	(((idx) * 4 * 4) + 0x14)
+
+#define AST2600_I3CG_REG0_SDA_PULLUP_EN_MASK	GENMASK(29, 28)
+#define AST2600_I3CG_REG0_SDA_PULLUP_EN_2K	(0x0 << 28)
+#define AST2600_I3CG_REG0_SDA_PULLUP_EN_750	(0x2 << 28)
+
+#define AST2600_I3CG_REG1_I2C_MODE		BIT(0)
+#define AST2600_I3CG_REG1_TEST_MODE		BIT(1)
+#define AST2600_I3CG_REG1_ACT_MODE_MASK		GENMASK(3, 2)
+#define AST2600_I3CG_REG1_ACT_MODE(x)		(((x) << 2) & AST2600_I3CG_REG1_ACT_MODE_MASK)
+#define AST2600_I3CG_REG1_PENDING_INT_MASK	GENMASK(7, 4)
+#define AST2600_I3CG_REG1_PENDING_INT(x)	(((x) << 4) & AST2600_I3CG_REG1_PENDING_INT_MASK)
+#define AST2600_I3CG_REG1_SA_MASK		GENMASK(14, 8)
+#define AST2600_I3CG_REG1_SA(x)			(((x) << 8) & AST2600_I3CG_REG1_SA_MASK)
+#define AST2600_I3CG_REG1_SA_EN			BIT(15)
+#define AST2600_I3CG_REG1_INST_ID_MASK		GENMASK(19, 16)
+#define AST2600_I3CG_REG1_INST_ID(x)		(((x) << 16) & AST2600_I3CG_REG1_INST_ID_MASK)
+
+#define AST2600_DEFAULT_SDA_PULLUP_OHMS		2000
+
+struct ast2600_i3c_platform_data {
+	struct regmap *global_regs;
+	unsigned int global_idx;
+	unsigned int sda_pullup;
+};
+
+static int ast2600_i3c_pullup_to_reg(unsigned int ohms, u32 *regp)
+{
+	u32 reg;
+
+	switch (ohms) {
+	case 2000:
+		reg = AST2600_I3CG_REG0_SDA_PULLUP_EN_2K;
+		break;
+	case 750:
+		reg = AST2600_I3CG_REG0_SDA_PULLUP_EN_750;
+		break;
+	case 545:
+		reg = AST2600_I3CG_REG0_SDA_PULLUP_EN_2K |
+			AST2600_I3CG_REG0_SDA_PULLUP_EN_750;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (regp)
+		*regp = reg;
+
+	return 0;
+}
+
+static int ast2600_i3c_init(struct dw_i3c_master *master)
+{
+	struct ast2600_i3c_platform_data *pdata = master->platform_data;
+	u32 reg = 0;
+	int rc;
+
+	/* reg0: set SDA pullup values */
+	rc = ast2600_i3c_pullup_to_reg(pdata->sda_pullup, &reg);
+	if (rc)
+		return rc;
+
+	rc = regmap_write(pdata->global_regs,
+			  AST2600_I3CG_REG0(pdata->global_idx), reg);
+	if (rc)
+		return rc;
+
+	/* reg1: set up the instance id, but leave everything else disabled,
+	 * as it's all for client mode
+	 */
+	reg = AST2600_I3CG_REG1_INST_ID(pdata->global_idx);
+	rc = regmap_write(pdata->global_regs,
+			  AST2600_I3CG_REG1(pdata->global_idx), reg);
+
+	return rc;
+}
+
+const struct dw_i3c_platform_ops ast2600_i3c_ops = {
+	.init = ast2600_i3c_init,
+};
+
+static int ast2600_i3c_probe(struct platform_device *pdev)
+{

drivers/i3c/master/ast2600-i3c-master.c new file +40 -0

+	pdata = (void *)(dw_i3c + 1);
+
+	rc = of_parse_phandle_with_fixed_args(np, "aspeed,global-regs", 1, 0,
+					      &gspec);
+	if (rc)
+		return -ENODEV;
+
+	pdata->global_regs = syscon_node_to_regmap(gspec.np);
+	of_node_put(gspec.np);
+
+	if (IS_ERR(pdata->global_regs))
+		return PTR_ERR(pdata->global_regs);
+
+	pdata->global_idx = gspec.args[0];
+
+	rc = of_property_read_u32(np, "sda-pullup-ohms", &pdata->sda_pullup);
+	if (rc)
+		pdata->sda_pullup = AST2600_DEFAULT_SDA_PULLUP_OHMS;
+
+	rc = ast2600_i3c_pullup_to_reg(pdata->sda_pullup, NULL);
+	if (rc)
+		dev_err(&dw_i3c->base.dev, "invalid sda-pullup value %d\n",
+			pdata->sda_pullup);
+
+	dw_i3c->platform_ops = &ast2600_i3c_ops;
+	dw_i3c->platform_data = pdata;
+	rc = dw_i3c_common_probe(dw_i3c, pdev);
+
+	return rc;
+}
+
+static int ast2600_i3c_remove(struct platform_device *pdev)
+{
+	struct dw_i3c_master *dw_i3c = platform_get_drvdata(pdev);
+
+	return dw_i3c_common_remove(dw_i3c);
+}
+
+static const struct of_device_id ast2600_i3c_master_of_match[] = {
+	{ .compatible = "aspeed,ast2600-i3c", },

drivers/i3c/master/ast2600-i3c-master.c new file +7 -0

+	},
+};
+module_platform_driver(ast2600_i3c_driver);
+
+MODULE_AUTHOR("Jeremy Kerr <[email protected]>");
+MODULE_DESCRIPTION("ASPEED AST2600 I3C driver");
+MODULE_LICENSE("GPL");

How about wrapping the dw_i3c_master struct in an as2600_master struct and then you can use container of, and simply do sizeof(struct ast2600_master) ?

Also removes the need below to set pdata at-all

Quoted 7 lines

+static struct platform_driver ast2600_i3c_driver = { +       .probe = ast2600_i3c_probe,
+       .remove = ast2600_i3c_remove,
+       .driver = {
+               .name = "ast2600-i3c-master", +               .of_match_table = of_match_ptr(ast2600_i3c_master_of_match),

given this is probably an of-device only, of_match_ptr not needed here?

Thanks for the change, especially IBI features in other threads. From my understanding, ASPEED AST2600 is a SoC which uses Synopsys' I3C IP core, and several different registers, especially the pull-up resistor.
If so, I am wondering if this is the right place to add ast2600-i3c-master.c, given that all current three xxx-i3c-master.c drivers in this directory are from IP providers directly. What about moving it under ~/driver/soc/?

Hi Zenghu,

Quoted 8 lines

Thanks for the change, especially IBI features in other threads. From my understanding, ASPEED AST2600 is a SoC which uses Synopsys' I3C IP core, and several different registers, especially the pull-up resistor.
If so, I am wondering if this is the right place to add ast2600-i3c-master.c, given that all current three xxx-i3c-master.c drivers in this directory are from IP providers directly. What about moving it under ~/driver/soc/?

It's my understanding that drivers/soc/ is for smaller parts of SoC-specific functions, rather than implementing SoC driver instances for existing subsystems.

I'd prefer to keep it with the i3c controller drivers; this means we can keep the dw platform API as contained as possible (ie., within drivers/i3c/master/). I expect that we will need some coordination of changes until we have the platform-specific behaviour mostly described (see the IBI series for another hook), and so coordinating changes between drivers/soc/ and drivers/i3c/ may make things more complicated than necessary.

There's certainly precedence for this pattern:

* the aspeed ethernet mac is provided by the ftgmac100 driver plus some SoC-specific behaviour; that's entirely within drivers/net/

* the aspeed VUART device is essentially a 16550 plus extra registers; that's entirely within drivers/tty/