1 files changed, 96 insertions, 44 deletions

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index 76346e32f40..2d3260571b5 100644
--- a/drivers/pwm/pwm-sti.c
+++ b/drivers/pwm/pwm-sti.c
@@ -58,6 +58,7 @@ struct sti_pwm_chip {
 	struct regmap_field *pwm_int_en;
 	unsigned long *pwm_periods;
 	struct pwm_chip chip;
+	struct pwm_device *cur;
 	void __iomem *mmio;
 };
 
@@ -99,6 +100,24 @@ static void sti_pwm_calc_periods(struct sti_pwm_chip *pc)
 	}
 }
 
+/* Calculate the number of PWM devices configured with a period. */
+static unsigned int sti_pwm_count_configured(struct pwm_chip *chip)
+{
+	struct pwm_device *pwm;
+	unsigned int ncfg = 0;
+	unsigned int i;
+
+	for (i = 0; i < chip->npwm; i++) {
+		pwm = &chip->pwms[i];
+		if (test_bit(PWMF_REQUESTED, &pwm->flags)) {
+			if (pwm_get_period(pwm))
+				ncfg++;
+		}
+	}
+
+	return ncfg;
+}
+
 static int sti_pwm_cmp_periods(const void *key, const void *elt)
 {
 	unsigned long i = *(unsigned long *)key;
@@ -124,57 +143,90 @@ static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 {
 	struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
 	struct sti_pwm_compat_data *cdata = pc->cdata;
+	struct pwm_device *cur = pc->cur;
 	struct device *dev = pc->dev;
-	unsigned int prescale, pwmvalx;
+	unsigned int prescale = 0, pwmvalx;
 	unsigned long *found;
 	int ret;
-
-	/*
-	 * Search for matching period value. The corresponding index is our
-	 * prescale value
+	unsigned int ncfg;
+	bool period_same = false;
+
+	ncfg = sti_pwm_count_configured(chip);
+	if (ncfg)
+		period_same = (period_ns == pwm_get_period(cur));
+
+	/* Allow configuration changes if one of the
+	 * following conditions satisfy.
+	 * 1. No channels have been configured.
+	 * 2. Only one channel has been configured and the new request
+	 *    is for the same channel.
+	 * 3. Only one channel has been configured and the new request is
+	 *    for a new channel and period of the new channel is same as
+	 *    the current configured period.
+	 * 4. More than one channels are configured and period of the new
+	 *    requestis the same as the current period.
 	 */
-	found = bsearch(&period_ns, &pc->pwm_periods[0],
-			cdata->max_prescale + 1, sizeof(unsigned long),
-			sti_pwm_cmp_periods);
-	if (!found) {
-		dev_err(dev, "failed to find matching period\n");
+	if (!ncfg ||
+	    ((ncfg == 1) && (pwm->hwpwm == cur->hwpwm)) ||
+	    ((ncfg == 1) && (pwm->hwpwm != cur->hwpwm) && period_same) ||
+	    ((ncfg > 1) && period_same)) {
+		/* Enable clock before writing to PWM registers. */
+		ret = clk_enable(pc->clk);
+		if (ret)
+			return ret;
+
+		if (!period_same) {
+			/*
+			 * Search for matching period value.
+			 * The corresponding index is our prescale value.
+			 */
+			found = bsearch(&period_ns, &pc->pwm_periods[0],
+					cdata->max_prescale + 1,
+					sizeof(unsigned long),
+					sti_pwm_cmp_periods);
+			if (!found) {
+				dev_err(dev,
+					"failed to find matching period\n");
+				ret = -EINVAL;
+				goto clk_dis;
+			}
+			prescale = found - &pc->pwm_periods[0];
+
+			ret =
+			regmap_field_write(pc->prescale_low,
+					   prescale & PWM_PRESCALE_LOW_MASK);
+			if (ret)
+				goto clk_dis;
+
+			ret =
+			regmap_field_write(pc->prescale_high,
+				(prescale & PWM_PRESCALE_HIGH_MASK) >> 4);
+			if (ret)
+				goto clk_dis;
+		}
+
+		/*
+		 * When PWMVal == 0, PWM pulse = 1 local clock cycle.
+		 * When PWMVal == max_pwm_count,
+		 * PWM pulse = (max_pwm_count + 1) local cycles,
+		 * that is continuous pulse: signal never goes low.
+		 */
+		pwmvalx = cdata->max_pwm_cnt * duty_ns / period_ns;
+
+		ret = regmap_write(pc->regmap, STI_DS_REG(pwm->hwpwm), pwmvalx);
+		if (ret)
+			goto clk_dis;
+
+		ret = regmap_field_write(pc->pwm_int_en, 0);
+
+		pc->cur = pwm;
+
+		dev_dbg(dev, "prescale:%u, period:%i, duty:%i, pwmvalx:%u\n",
+			prescale, period_ns, duty_ns, pwmvalx);
+	} else {
 		return -EINVAL;
 	}
 
-	prescale = found - &pc->pwm_periods[0];
-
-	/*
-	 * When PWMVal == 0, PWM pulse = 1 local clock cycle.
-	 * When PWMVal == max_pwm_count,
-	 * PWM pulse = (max_pwm_count + 1) local cycles,
-	 * that is continuous pulse: signal never goes low.
-	 */
-	pwmvalx = cdata->max_pwm_cnt * duty_ns / period_ns;
-
-	dev_dbg(dev, "prescale:%u, period:%i, duty:%i, pwmvalx:%u\n",
-		prescale, period_ns, duty_ns, pwmvalx);
-
-	/* Enable clock before writing to PWM registers */
-	ret = clk_enable(pc->clk);
-	if (ret)
-		return ret;
-
-	ret = regmap_field_write(pc->prescale_low,
-				 prescale & PWM_PRESCALE_LOW_MASK);
-	if (ret)
-		goto clk_dis;
-
-	ret = regmap_field_write(pc->prescale_high,
-				 (prescale & PWM_PRESCALE_HIGH_MASK) >> 4);
-	if (ret)
-		goto clk_dis;
-
-	ret = regmap_write(pc->regmap, STI_PWMVAL(pwm->hwpwm), pwmvalx);
-	if (ret)
-		goto clk_dis;
-
-	ret = regmap_field_write(pc->pwm_int_en, 0);
-
 clk_dis:
 	clk_disable(pc->clk);
 	return ret;