i3c: ast2600: Add AST2600 platform-specific driver

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 <jk@codeconstruct.com.au>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20230331091501.3800299-4-jk@codeconstruct.com.au
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

diff --git a/MAINTAINERS b/MAINTAINERS
index 8d5bc22..cb91cc1 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9713,6 +9713,12 @@ 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 <jk@codeconstruct.com.au>
+S:     Maintained
+F:     Documentation/devicetree/bindings/i3c/aspeed,ast2600-i3c.yaml
+F:     drivers/i3c/master/ast2600-i3c-master.c
+
 I3C SUBSYSTEM
 M:     Alexandre Belloni <alexandre.belloni@bootlin.com>
 L:     linux-i3c@lists.infradead.org (moderated for non-subscribers)

diff --git a/drivers/i3c/master/Kconfig b/drivers/i3c/master/Kconfig
index 3b8f959..90dee3e 100644 (file)
--- a/drivers/i3c/master/Kconfig
+++ b/drivers/i3c/master/Kconfig
@@ -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

diff --git a/drivers/i3c/master/Makefile b/drivers/i3c/master/Makefile
index b3fee0f..3e97960 100644 (file)
--- a/drivers/i3c/master/Makefile
+++ b/drivers/i3c/master/Makefile
@@ -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/

diff --git a/drivers/i3c/master/ast2600-i3c-master.c b/drivers/i3c/master/ast2600-i3c-master.c
new file mode 100644 (file)
index 0000000..b3f0fe1
--- /dev/null
+++ b/drivers/i3c/master/ast2600-i3c-master.c
@@ -0,0 +1,168 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2023 Code Construct
+ *
+ * Author: Jeremy Kerr <jk@codeconstruct.com.au>
+ */
+
+#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 {
+       struct dw_i3c_master dw;
+       struct regmap *global_regs;
+       unsigned int global_idx;
+       unsigned int sda_pullup;
+};
+
+static struct ast2600_i3c *to_ast2600_i3c(struct dw_i3c_master *dw)
+{
+       return container_of(dw, struct ast2600_i3c, dw);
+}
+
+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 *dw)
+{
+       struct ast2600_i3c *i3c = to_ast2600_i3c(dw);
+       u32 reg = 0;
+       int rc;
+
+       /* reg0: set SDA pullup values */
+       rc = ast2600_i3c_pullup_to_reg(i3c->sda_pullup, &reg);
+       if (rc)
+               return rc;
+
+       rc = regmap_write(i3c->global_regs,
+                         AST2600_I3CG_REG0(i3c->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(i3c->global_idx);
+       rc = regmap_write(i3c->global_regs,
+                         AST2600_I3CG_REG1(i3c->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)
+{
+       struct device_node *np = pdev->dev.of_node;
+       struct of_phandle_args gspec;
+       struct ast2600_i3c *i3c;
+       int rc;
+
+       i3c = devm_kzalloc(&pdev->dev, sizeof(*i3c), GFP_KERNEL);
+       if (!i3c)
+               return -ENOMEM;
+
+       rc = of_parse_phandle_with_fixed_args(np, "aspeed,global-regs", 1, 0,
+                                             &gspec);
+       if (rc)
+               return -ENODEV;
+
+       i3c->global_regs = syscon_node_to_regmap(gspec.np);
+       of_node_put(gspec.np);
+
+       if (IS_ERR(i3c->global_regs))
+               return PTR_ERR(i3c->global_regs);
+
+       i3c->global_idx = gspec.args[0];
+
+       rc = of_property_read_u32(np, "sda-pullup-ohms", &i3c->sda_pullup);
+       if (rc)
+               i3c->sda_pullup = AST2600_DEFAULT_SDA_PULLUP_OHMS;
+
+       rc = ast2600_i3c_pullup_to_reg(i3c->sda_pullup, NULL);
+       if (rc)
+               dev_err(&pdev->dev, "invalid sda-pullup value %d\n",
+                       i3c->sda_pullup);
+
+       i3c->dw.platform_ops = &ast2600_i3c_ops;
+       return dw_i3c_common_probe(&i3c->dw, pdev);
+}
+
+static void ast2600_i3c_remove(struct platform_device *pdev)
+{
+       struct dw_i3c_master *dw_i3c = platform_get_drvdata(pdev);
+
+       dw_i3c_common_remove(dw_i3c);
+}
+
+static const struct of_device_id ast2600_i3c_master_of_match[] = {
+       { .compatible = "aspeed,ast2600-i3c", },
+       {},
+};
+MODULE_DEVICE_TABLE(of, ast2600_i3c_master_of_match);
+
+static struct platform_driver ast2600_i3c_driver = {
+       .probe = ast2600_i3c_probe,
+       .remove_new = ast2600_i3c_remove,
+       .driver = {
+               .name = "ast2600-i3c-master",
+               .of_match_table = ast2600_i3c_master_of_match,
+       },
+};
+module_platform_driver(ast2600_i3c_driver);
+
+MODULE_AUTHOR("Jeremy Kerr <jk@codeconstruct.com.au>");
+MODULE_DESCRIPTION("ASPEED AST2600 I3C driver");
+MODULE_LICENSE("GPL");