pwm: sti: Sync between enable/disable calls

ST PWM IP has a common enable/disable control for all the PWM
channels on a PWM cell. Disables PWM output on the PWM HW only
when disable is called for the last channel.

Signed-off-by: Ajit Pal Singh <ajitpal.singh@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

1 files changed, 30 insertions, 14 deletions

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index 2d3260571b5a..f98afe4906fb 100644
--- a/drivers/pwm/pwm-sti.c
+++ b/drivers/pwm/pwm-sti.c
@@ -59,6 +59,8 @@ struct sti_pwm_chip {
         unsigned long *pwm_periods;
         struct pwm_chip chip;
         struct pwm_device *cur;
+        unsigned int en_count;
+        struct mutex sti_pwm_lock; /* To sync between enable/disable calls */
         void __iomem *mmio;
 };
 
@@ -236,32 +238,44 @@ static int sti_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
         struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
         struct device *dev = pc->dev;
-        int ret;
-
-        ret = clk_enable(pc->clk);
-        if (ret)
-                return ret;
+        int ret = 0;
 
-        ret = regmap_field_write(pc->pwm_en, 1);
-        if (ret)
-                dev_err(dev, "%s,pwm_en write failed\n", __func__);
+        /*
+         * Since we have a common enable for all PWM channels,
+         * do not enable if already enabled.
+         */
+        mutex_lock(&pc->sti_pwm_lock);
+        if (!pc->en_count) {
+                ret = clk_enable(pc->clk);
+                if (ret)
+                        goto out;
 
+                ret = regmap_field_write(pc->pwm_en, 1);
+                if (ret) {
+                        dev_err(dev, "failed to enable PWM device:%d\n",
+                                pwm->hwpwm);
+                        goto out;
+                }
+        }
+        pc->en_count++;
+out:
+        mutex_unlock(&pc->sti_pwm_lock);
         return ret;
 }
 
 static void sti_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
         struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
-        struct device *dev = pc->dev;
-        unsigned int val;
 
+        mutex_lock(&pc->sti_pwm_lock);
+        if (--pc->en_count) {
+                mutex_unlock(&pc->sti_pwm_lock);
+                return;
+        }
         regmap_field_write(pc->pwm_en, 0);
 
-        regmap_read(pc->regmap, STI_CNT, &val);
-
-        dev_dbg(dev, "pwm counter :%u\n", val);
-
         clk_disable(pc->clk);
+        mutex_unlock(&pc->sti_pwm_lock);
 }
 
 static const struct pwm_ops sti_pwm_ops = {
@@ -352,6 +366,8 @@ static int sti_pwm_probe(struct platform_device *pdev)
 
         pc->cdata = cdata;
         pc->dev = dev;
+        pc->en_count = 0;
+        mutex_init(&pc->sti_pwm_lock);
 
         ret = sti_pwm_probe_dt(pc);
         if (ret)