i2c: mv64xxx: Add reset deassert call

The Allwinner A31 SoC using that IP has a reset controller maintaining
it reset unless told otherwise.

Add some optional reset support to the driver.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Reviewed-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

2 files changed, 20 insertions, 2 deletions

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index f5ed03164d86..70bcad941657 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -528,6 +528,7 @@ config I2C_MPC
 config I2C_MV64XXX
         tristate "Marvell mv64xxx I2C Controller"
         depends on (MV64X60 || PLAT_ORION || ARCH_SUNXI)
+        select RESET_CONTROLLER
         help
           If you say yes to this option, support will be included for the
           built-in I2C interface on the Marvell 64xxx line of host bridges.
diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
index d52d84937ad3..1bb69b6f746d 100644
--- a/drivers/i2c/busses/i2c-mv64xxx.c
+++ b/drivers/i2c/busses/i2c-mv64xxx.c
@@ -17,6 +17,7 @@
 #include <linux/interrupt.h>
 #include <linux/mv643xx_i2c.h>
 #include <linux/platform_device.h>
+#include <linux/reset.h>
 #include <linux/io.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
@@ -148,6 +149,7 @@ struct mv64xxx_i2c_data {
         bool                    offload_enabled;
 /* 5us delay in order to avoid repeated start timing violation */
         bool                    errata_delay;
+        struct reset_control    *rstc;
 };
 
 static struct mv64xxx_i2c_regs mv64xxx_i2c_regs_mv64xxx = {
@@ -759,6 +761,16 @@ mv64xxx_of_config(struct mv64xxx_i2c_data *drv_data,
         }
         drv_data->irq = irq_of_parse_and_map(np, 0);
 
+        drv_data->rstc = devm_reset_control_get(dev, NULL);
+        if (IS_ERR(drv_data->rstc)) {
+                if (PTR_ERR(drv_data->rstc) == -EPROBE_DEFER) {
+                        rc = -EPROBE_DEFER;
+                        goto out;
+                }
+        } else {
+                reset_control_deassert(drv_data->rstc);
+        }
+
         /* Its not yet defined how timeouts will be specified in device tree.
          * So hard code the value to 1 second.
          */
@@ -845,7 +857,7 @@ mv64xxx_i2c_probe(struct platform_device *pd)
         }
         if (drv_data->irq < 0) {
                 rc = -ENXIO;
-                goto exit_clk;
+                goto exit_reset;
         }
 
         drv_data->adapter.dev.parent = &pd->dev;
@@ -865,7 +877,7 @@ mv64xxx_i2c_probe(struct platform_device *pd)
                 dev_err(&drv_data->adapter.dev,
                         "mv64xxx: Can't register intr handler irq%d: %d\n",
                         drv_data->irq, rc);
-                goto exit_clk;
+                goto exit_reset;
         } else if ((rc = i2c_add_numbered_adapter(&drv_data->adapter)) != 0) {
                 dev_err(&drv_data->adapter.dev,
                         "mv64xxx: Can't add i2c adapter, rc: %d\n", -rc);
@@ -876,6 +888,9 @@ mv64xxx_i2c_probe(struct platform_device *pd)
 
 exit_free_irq:
         free_irq(drv_data->irq, drv_data);
+exit_reset:
+        if (pd->dev.of_node && !IS_ERR(drv_data->rstc))
+                reset_control_assert(drv_data->rstc);
 exit_clk:
 #if defined(CONFIG_HAVE_CLK)
         /* Not all platforms have a clk */
@@ -894,6 +909,8 @@ mv64xxx_i2c_remove(struct platform_device *dev)
 
         i2c_del_adapter(&drv_data->adapter);
         free_irq(drv_data->irq, drv_data);
+        if (dev->dev.of_node && !IS_ERR(drv_data->rstc))
+                reset_control_assert(drv_data->rstc);
 #if defined(CONFIG_HAVE_CLK)
         /* Not all platforms have a clk */
         if (!IS_ERR(drv_data->clk)) {