pwm: tegra: Add support for reset control

Add reset control of the PWM controller to reset it before
accessing the PWM register.

Signed-off-by: Rohith Seelaboyina <rseelaboyina@nvidia.com>
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/drivers/pwm/pwm-tegra.c b/drivers/pwm/pwm-tegra.c
index 3cbb32d8064f..097658e0751b 100644
--- a/drivers/pwm/pwm-tegra.c
+++ b/drivers/pwm/pwm-tegra.c
@@ -29,6 +29,7 @@
 #include <linux/pwm.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
+#include <linux/reset.h>
 
 #define PWM_ENABLE      (1 << 31)
 #define PWM_DUTY_WIDTH  8
@@ -41,6 +42,7 @@ struct tegra_pwm_chip {
         struct device *dev;
 
         struct clk *clk;
+        struct reset_control*rst;
 
         void __iomem *regs;
 };
@@ -187,6 +189,15 @@ static int tegra_pwm_probe(struct platform_device *pdev)
         if (IS_ERR(pwm->clk))
                 return PTR_ERR(pwm->clk);
 
+        pwm->rst = devm_reset_control_get(&pdev->dev, "pwm");
+        if (IS_ERR(pwm->rst)) {
+                ret = PTR_ERR(pwm->rst);
+                dev_err(&pdev->dev, "Reset control is not found: %d\n", ret);
+                return ret;
+        }
+
+        reset_control_deassert(pwm->rst);
+
         pwm->chip.dev = &pdev->dev;
         pwm->chip.ops = &tegra_pwm_ops;
         pwm->chip.base = -1;
@@ -195,6 +206,7 @@ static int tegra_pwm_probe(struct platform_device *pdev)
         ret = pwmchip_add(&pwm->chip);
         if (ret < 0) {
                 dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
+                reset_control_assert(pwm->rst);
                 return ret;
         }
 
@@ -205,10 +217,15 @@ static int tegra_pwm_remove(struct platform_device *pdev)
 {
         struct tegra_pwm_chip *pc = platform_get_drvdata(pdev);
         unsigned int i;
+        int err;
 
         if (WARN_ON(!pc))
                 return -ENODEV;
 
+        err = clk_prepare_enable(pc->clk);
+        if (err < 0)
+                return err;
+
         for (i = 0; i < pc->chip.npwm; i++) {
                 struct pwm_device *pwm = &pc->chip.pwms[i];
 
@@ -221,6 +238,9 @@ static int tegra_pwm_remove(struct platform_device *pdev)
                 clk_disable_unprepare(pc->clk);
         }
 
+        reset_control_assert(pc->rst);
+        clk_disable_unprepare(pc->clk);
+
         return pwmchip_remove(&pc->chip);
 }