1 files changed, 28 insertions, 0 deletions

diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c
index 89f9ca41d9af..a947c9095d9d 100644
--- a/drivers/pwm/pwm-atmel.c
+++ b/drivers/pwm/pwm-atmel.c
@@ -8,9 +8,11 @@
  */
 
 #include <linux/clk.h>
+#include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
@@ -21,6 +23,7 @@
 #define PWM_ENA                 0x04
 #define PWM_DIS                 0x08
 #define PWM_SR                  0x0C
+#define PWM_ISR                 0x1C
 /* Bit field in SR */
 #define PWM_SR_ALL_CH_ON        0x0F
 
@@ -60,6 +63,9 @@ struct atmel_pwm_chip {
         struct clk *clk;
         void __iomem *base;
 
+        unsigned int updated_pwms;
+        struct mutex isr_lock; /* ISR is cleared when read, ensure only one thread does that */
+
         void (*config)(struct pwm_chip *chip, struct pwm_device *pwm,
                        unsigned long dty, unsigned long prd);
 };
@@ -144,6 +150,10 @@ static int atmel_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
         val = (val & ~PWM_CMR_CPRE_MSK) | (pres & PWM_CMR_CPRE_MSK);
         atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val);
         atmel_pwm->config(chip, pwm, dty, prd);
+        mutex_lock(&atmel_pwm->isr_lock);
+        atmel_pwm->updated_pwms |= atmel_pwm_readl(atmel_pwm, PWM_ISR);
+        atmel_pwm->updated_pwms &= ~(1 << pwm->hwpwm);
+        mutex_unlock(&atmel_pwm->isr_lock);
 
         clk_disable(atmel_pwm->clk);
         return ret;
@@ -243,7 +253,22 @@ static int atmel_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 static void atmel_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
         struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
+        unsigned long timeout = jiffies + 2 * HZ;
+
+        /*
+         * Wait for at least a complete period to have passed before disabling a
+         * channel to be sure that CDTY has been updated
+         */
+        mutex_lock(&atmel_pwm->isr_lock);
+        atmel_pwm->updated_pwms |= atmel_pwm_readl(atmel_pwm, PWM_ISR);
+
+        while (!(atmel_pwm->updated_pwms & (1 << pwm->hwpwm)) &&
+               time_before(jiffies, timeout)) {
+                usleep_range(10, 100);
+                atmel_pwm->updated_pwms |= atmel_pwm_readl(atmel_pwm, PWM_ISR);
+        }
 
+        mutex_unlock(&atmel_pwm->isr_lock);
         atmel_pwm_writel(atmel_pwm, PWM_DIS, 1 << pwm->hwpwm);
 
         clk_disable(atmel_pwm->clk);
@@ -358,6 +383,8 @@ static int atmel_pwm_probe(struct platform_device *pdev)
         atmel_pwm->chip.npwm = 4;
         atmel_pwm->chip.can_sleep = true;
         atmel_pwm->config = data->config;
+        atmel_pwm->updated_pwms = 0;
+        mutex_init(&atmel_pwm->isr_lock);
 
         ret = pwmchip_add(&atmel_pwm->chip);
         if (ret < 0) {
@@ -379,6 +406,7 @@ static int atmel_pwm_remove(struct platform_device *pdev)
         struct atmel_pwm_chip *atmel_pwm = platform_get_drvdata(pdev);
 
         clk_unprepare(atmel_pwm->clk);
+        mutex_destroy(&atmel_pwm->isr_lock);
 
         return pwmchip_remove(&atmel_pwm->chip);
 }