i2c: designware: add reset interface

Some platforms like hi3660 need do reset first to allow accessing registers

Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Ramiro Oliveira <ramiro.oliveira@synopsys.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

2 files changed, 25 insertions, 4 deletions

diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index c1db3a5a340f..d9aaf1790e0e 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -88,6 +88,7 @@ struct dw_i2c_dev {
         void __iomem            *base;
         struct completion       cmd_complete;
         struct clk              *clk;
+        struct reset_control    *rst;
         u32                     (*get_clk_rate_khz) (struct dw_i2c_dev *dev);
         struct dw_pci_controller *controller;
         int                     cmd_err;
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 6ce431323125..79c4b4ea0539 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -38,6 +38,7 @@
 #include <linux/pm_runtime.h>
 #include <linux/property.h>
 #include <linux/io.h>
+#include <linux/reset.h>
 #include <linux/slab.h>
 #include <linux/acpi.h>
 #include <linux/platform_data/i2c-designware.h>
@@ -199,6 +200,14 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
         dev->irq = irq;
         platform_set_drvdata(pdev, dev);
 
+        dev->rst = devm_reset_control_get_optional_exclusive(&pdev->dev, NULL);
+        if (IS_ERR(dev->rst)) {
+                if (PTR_ERR(dev->rst) == -EPROBE_DEFER)
+                        return -EPROBE_DEFER;
+        } else {
+                reset_control_deassert(dev->rst);
+        }
+
         if (pdata) {
                 dev->clk_freq = pdata->i2c_scl_freq;
         } else {
@@ -235,12 +244,13 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
             && dev->clk_freq != 1000000 && dev->clk_freq != 3400000) {
                 dev_err(&pdev->dev,
                         "Only 100kHz, 400kHz, 1MHz and 3.4MHz supported");
-                return -EINVAL;
+                r = -EINVAL;
+                goto exit_reset;
         }
 
         r = i2c_dw_eval_lock_support(dev);
         if (r)
-                return r;
+                goto exit_reset;
 
         dev->functionality = I2C_FUNC_10BIT_ADDR | DW_IC_DEFAULT_FUNCTIONALITY;
 
@@ -286,10 +296,18 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
         }
 
         r = i2c_dw_probe(dev);
-        if (r && !dev->pm_runtime_disabled)
-                pm_runtime_disable(&pdev->dev);
+        if (r)
+                goto exit_probe;
 
         return r;
+
+exit_probe:
+        if (!dev->pm_runtime_disabled)
+                pm_runtime_disable(&pdev->dev);
+exit_reset:
+        if (!IS_ERR_OR_NULL(dev->rst))
+                reset_control_assert(dev->rst);
+        return r;
 }
 
 static int dw_i2c_plat_remove(struct platform_device *pdev)
@@ -306,6 +324,8 @@ static int dw_i2c_plat_remove(struct platform_device *pdev)
         pm_runtime_put_sync(&pdev->dev);
         if (!dev->pm_runtime_disabled)
                 pm_runtime_disable(&pdev->dev);
+        if (!IS_ERR_OR_NULL(dev->rst))
+                reset_control_assert(dev->rst);
 
         return 0;
 }