i2c: designware: Add Baikal-T1 System I2C support

Baikal-T1 System Controller is equipped with a dedicated I2C Controller
which functionality is based on the DW APB I2C IP-core, the only
difference in a way it' registers are accessed. There are three access
register provided in the System Controller registers map, which indirectly
address the normal DW APB I2C registers space. So in order to have the
Baikal-T1 System I2C Controller supported by the common DW APB I2C driver
we created a dedicated Dw I2C controller model quirk, which retrieves the
syscon regmap from the parental dt node and creates a new regmap based on
it.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index c748beaaa8903912b77cd1509edfce88c79471ff..14e2e93a5698c72fd9fb7f82817da88b6090c742 100644 (file)
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -541,8 +541,9 @@ config I2C_DESIGNWARE_SLAVE
 
 config I2C_DESIGNWARE_PLATFORM
        tristate "Synopsys DesignWare Platform"
-       select I2C_DESIGNWARE_CORE
        depends on (ACPI && COMMON_CLK) || !ACPI
+       select I2C_DESIGNWARE_CORE
+       select MFD_SYSCON if MIPS_BAIKAL_T1
        help
          If you say yes to this option, support will be included for the
          Synopsys DesignWare I2C adapter.

diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index f5bbe3d6bcf8bab2b0eda1ac6ae6a0efa13825cf..556673a1f61bd30cf4fbbb03a72f4f98244d3ade 100644 (file)
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -183,6 +183,7 @@ struct reset_control;
  * struct dw_i2c_dev - private i2c-designware data
  * @dev: driver model device node
  * @map: IO registers map
+ * @sysmap: System controller registers map
  * @base: IO registers pointer
  * @ext: Extended IO registers pointer
  * @cmd_complete: tx completion indicator
@@ -235,6 +236,7 @@ struct reset_control;
 struct dw_i2c_dev {
        struct device           *dev;
        struct regmap           *map;
+       struct regmap           *sysmap;
        void __iomem            *base;
        void __iomem            *ext;
        struct completion       cmd_complete;
@@ -290,6 +292,7 @@ struct dw_i2c_dev {
 #define ACCESS_NO_IRQ_SUSPEND  0x00000002
 
 #define MODEL_MSCC_OCELOT      0x00000100
+#define MODEL_BAIKAL_BT1       0x00000200
 #define MODEL_MASK             0x00000f00
 
 int i2c_dw_init_regmap(struct dw_i2c_dev *dev);

diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 9d467fa0e1634ff22d5d8224a3063e58f571c090..b55c730f28cf89f92d18d81016d87b39d71e4a04 100644 (file)
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -18,6 +18,7 @@
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
+#include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_data/i2c-designware.h>
@@ -25,6 +26,7 @@
 #include <linux/pm.h>
 #include <linux/pm_runtime.h>
 #include <linux/property.h>
+#include <linux/regmap.h>
 #include <linux/reset.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
@@ -58,6 +60,63 @@ MODULE_DEVICE_TABLE(acpi, dw_i2c_acpi_match);
 #endif
 
 #ifdef CONFIG_OF
+#define BT1_I2C_CTL                    0x100
+#define BT1_I2C_CTL_ADDR_MASK          GENMASK(7, 0)
+#define BT1_I2C_CTL_WR                 BIT(8)
+#define BT1_I2C_CTL_GO                 BIT(31)
+#define BT1_I2C_DI                     0x104
+#define BT1_I2C_DO                     0x108
+
+static int bt1_i2c_read(void *context, unsigned int reg, unsigned int *val)
+{
+       struct dw_i2c_dev *dev = context;
+       int ret;
+
+       /*
+        * Note these methods shouldn't ever fail because the system controller
+        * registers are memory mapped. We check the return value just in case.
+        */
+       ret = regmap_write(dev->sysmap, BT1_I2C_CTL,
+                          BT1_I2C_CTL_GO | (reg & BT1_I2C_CTL_ADDR_MASK));
+       if (ret)
+               return ret;
+
+       return regmap_read(dev->sysmap, BT1_I2C_DO, val);
+}
+
+static int bt1_i2c_write(void *context, unsigned int reg, unsigned int val)
+{
+       struct dw_i2c_dev *dev = context;
+       int ret;
+
+       ret = regmap_write(dev->sysmap, BT1_I2C_DI, val);
+       if (ret)
+               return ret;
+
+       return regmap_write(dev->sysmap, BT1_I2C_CTL,
+               BT1_I2C_CTL_GO | BT1_I2C_CTL_WR | (reg & BT1_I2C_CTL_ADDR_MASK));
+}
+
+static struct regmap_config bt1_i2c_cfg = {
+       .reg_bits = 32,
+       .val_bits = 32,
+       .reg_stride = 4,
+       .fast_io = true,
+       .reg_read = bt1_i2c_read,
+       .reg_write = bt1_i2c_write,
+       .max_register = DW_IC_COMP_TYPE,
+};
+
+static int bt1_i2c_request_regs(struct dw_i2c_dev *dev)
+{
+       dev->sysmap = syscon_node_to_regmap(dev->dev->of_node->parent);
+       if (IS_ERR(dev->sysmap))
+               return PTR_ERR(dev->sysmap);
+
+       dev->map = devm_regmap_init(dev->dev, NULL, dev, &bt1_i2c_cfg);
+       return PTR_ERR_OR_ZERO(dev->map);
+}
+
 #define MSCC_ICPU_CFG_TWI_DELAY                0x0
 #define MSCC_ICPU_CFG_TWI_DELAY_ENABLE BIT(0)
 #define MSCC_ICPU_CFG_TWI_SPIKE_FILTER 0x4
@@ -90,10 +149,16 @@ static int dw_i2c_of_configure(struct platform_device *pdev)
 static const struct of_device_id dw_i2c_of_match[] = {
        { .compatible = "snps,designware-i2c", },
        { .compatible = "mscc,ocelot-i2c", .data = (void *)MODEL_MSCC_OCELOT },
+       { .compatible = "baikal,bt1-sys-i2c", .data = (void *)MODEL_BAIKAL_BT1 },
        {},
 };
 MODULE_DEVICE_TABLE(of, dw_i2c_of_match);
 #else
+static int bt1_i2c_request_regs(struct dw_i2c_dev *dev)
+{
+       return -ENODEV;
+}
+
 static inline int dw_i2c_of_configure(struct platform_device *pdev)
 {
        return -ENODEV;
@@ -111,10 +176,19 @@ static void dw_i2c_plat_pm_cleanup(struct dw_i2c_dev *dev)
 static int dw_i2c_plat_request_regs(struct dw_i2c_dev *dev)
 {
        struct platform_device *pdev = to_platform_device(dev->dev);
+       int ret;
 
-       dev->base = devm_platform_ioremap_resource(pdev, 0);
+       switch (dev->flags & MODEL_MASK) {
+       case MODEL_BAIKAL_BT1:
+               ret = bt1_i2c_request_regs(dev);
+               break;
+       default:
+               dev->base = devm_platform_ioremap_resource(pdev, 0);
+               ret = PTR_ERR_OR_ZERO(dev->base);
+               break;
+       }
 
-       return PTR_ERR_OR_ZERO(dev->base);
+       return ret;
 }
 
 static int dw_i2c_plat_probe(struct platform_device *pdev)