[PATCH v2 3/4] pwm: kona: Fix enable, disable and config procedures
From: Scott Branden
Date: Tue Nov 25 2014 - 14:41:34 EST
From: Arun Ramamurthy <arunrama@xxxxxxxxxxxx>
- Added helper functions to set and clear smooth and trigger bits
- Added 400ns delays when clearing and setting trigger bit as requied
by spec
- Added helper function to write prescale and other settings
- Updated config procedure to match spec
- Added code to handle pwn config when channel is disabled
- Updated disable procedure to match spec
Signed-off-by: Arun Ramamurthy <arunrama@xxxxxxxxxxxx>
Reviewed-by: Ray Jui <rjui@xxxxxxxxxxxx>
Signed-off-by: Scott Branden <sbranden@xxxxxxxxxxxx>
---
drivers/pwm/pwm-bcm-kona.c | 100 +++++++++++++++++++++++++++++++++++----------
1 file changed, 78 insertions(+), 22 deletions(-)
diff --git a/drivers/pwm/pwm-bcm-kona.c b/drivers/pwm/pwm-bcm-kona.c
index fa0b5bf..06fa983 100644
--- a/drivers/pwm/pwm-bcm-kona.c
+++ b/drivers/pwm/pwm-bcm-kona.c
@@ -65,6 +65,10 @@
#define DUTY_CYCLE_HIGH_MIN (0x00000000)
#define DUTY_CYCLE_HIGH_MAX (0x00ffffff)
+/* The delay required after clearing or setting
+ PWMOUT_ENABLE*/
+#define PWMOUT_ENABLE_HOLD_DELAY 400
+
struct kona_pwmc {
struct pwm_chip chip;
void __iomem *base;
@@ -76,28 +80,70 @@ static inline struct kona_pwmc *to_kona_pwmc(struct pwm_chip *_chip)
return container_of(_chip, struct kona_pwmc, chip);
}
-static void kona_pwmc_apply_settings(struct kona_pwmc *kp, unsigned int chan)
+static inline void kona_pwmc_set_trigger(struct kona_pwmc *kp,
+ unsigned int chan)
{
unsigned int value = readl(kp->base + PWM_CONTROL_OFFSET);
- /* Clear trigger bit but set smooth bit to maintain old output */
- value |= 1 << PWM_CONTROL_SMOOTH_SHIFT(chan);
+ /* set trigger bit to enable channel */
+ value |= 1 << PWM_CONTROL_TRIGGER_SHIFT(chan);
+ writel(value, kp->base + PWM_CONTROL_OFFSET);
+ ndelay(PWMOUT_ENABLE_HOLD_DELAY);
+}
+static inline void kona_pwmc_clear_trigger(struct kona_pwmc *kp,
+ unsigned int chan)
+{
+ unsigned int value = readl(kp->base + PWM_CONTROL_OFFSET);
+
+ /* Clear trigger bit */
value &= ~(1 << PWM_CONTROL_TRIGGER_SHIFT(chan));
writel(value, kp->base + PWM_CONTROL_OFFSET);
+ ndelay(PWMOUT_ENABLE_HOLD_DELAY);
+}
- /* Set trigger bit and clear smooth bit to apply new settings */
+static inline void kona_pwmc_clear_smooth(struct kona_pwmc *kp,
+ unsigned int chan)
+{
+ unsigned int value = readl(kp->base + PWM_CONTROL_OFFSET);
+
+ /* Clear smooth bit */
value &= ~(1 << PWM_CONTROL_SMOOTH_SHIFT(chan));
- value |= 1 << PWM_CONTROL_TRIGGER_SHIFT(chan);
writel(value, kp->base + PWM_CONTROL_OFFSET);
}
+static inline void kona_pwmc_set_smooth(struct kona_pwmc *kp, unsigned int chan)
+{
+ unsigned int value = readl(kp->base + PWM_CONTROL_OFFSET);
+
+ /* set smooth bit to maintain old output */
+ value |= 1 << PWM_CONTROL_SMOOTH_SHIFT(chan);
+ writel(value, kp->base + PWM_CONTROL_OFFSET);
+}
+
+static void kona_pwmc_write_settings(struct kona_pwmc *kp, unsigned int chan,
+ unsigned long prescale, unsigned long pc,
+ unsigned long dc)
+{
+ unsigned int value;
+
+ value = readl(kp->base + PRESCALE_OFFSET);
+ value &= ~PRESCALE_MASK(chan);
+ value |= prescale << PRESCALE_SHIFT(chan);
+ writel(value, kp->base + PRESCALE_OFFSET);
+
+ writel(pc, kp->base + PERIOD_COUNT_OFFSET(chan));
+
+ writel(dc, kp->base + DUTY_CYCLE_HIGH_OFFSET(chan));
+
+}
+
static int kona_pwmc_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
struct kona_pwmc *kp = to_kona_pwmc(chip);
u64 val, div, rate;
unsigned long prescale = PRESCALE_MIN, pc, dc;
- unsigned int value, chan = pwm->hwpwm;
+ unsigned int ret, chan = pwm->hwpwm;
/*
* Find period count, duty count and prescale to suit duty_ns and
@@ -133,19 +179,30 @@ static int kona_pwmc_config(struct pwm_chip *chip, struct pwm_device *pwm,
return -EINVAL;
}
- /* If the PWM channel is enabled, write the settings to the HW */
- if (test_bit(PWMF_ENABLED, &pwm->flags)) {
- value = readl(kp->base + PRESCALE_OFFSET);
- value &= ~PRESCALE_MASK(chan);
- value |= prescale << PRESCALE_SHIFT(chan);
- writel(value, kp->base + PRESCALE_OFFSET);
- writel(pc, kp->base + PERIOD_COUNT_OFFSET(chan));
+ /* If the PWM channel is not enabled, enable the clock */
+ if (!test_bit(PWMF_ENABLED, &pwm->flags)) {
+ ret = clk_prepare_enable(kp->clk);
+ if (ret < 0) {
+ dev_err(chip->dev, "failed to enable clock: %d\n", ret);
+ return ret;
+ }
+ }
- writel(dc, kp->base + DUTY_CYCLE_HIGH_OFFSET(chan));
+ /* Set smooth bit to maintain old output */
+ kona_pwmc_set_smooth(kp, chan);
+ kona_pwmc_clear_trigger(kp, chan);
+
+ /* apply new settings */
+ kona_pwmc_write_settings(kp, chan, prescale, pc, dc);
+
+ /*If the PWM is enabled, enable the channel with the new settings
+ and if not disable the clock*/
+ if (test_bit(PWMF_ENABLED, &pwm->flags))
+ kona_pwmc_set_trigger(kp, chan);
+ else
+ clk_disable_unprepare(kp->clk);
- kona_pwmc_apply_settings(kp, chan);
- }
return 0;
}
@@ -188,7 +245,6 @@ static int kona_pwmc_enable(struct pwm_chip *chip, struct pwm_device *pwm)
dev_err(chip->dev, "failed to enable clock: %d\n", ret);
return ret;
}
-
ret = kona_pwmc_config(chip, pwm, pwm->duty_cycle, pwm->period);
if (ret < 0) {
clk_disable_unprepare(kp->clk);
@@ -203,12 +259,12 @@ static void kona_pwmc_disable(struct pwm_chip *chip, struct pwm_device *pwm)
struct kona_pwmc *kp = to_kona_pwmc(chip);
unsigned int chan = pwm->hwpwm;
+ kona_pwmc_clear_smooth(kp, chan);
+ kona_pwmc_clear_trigger(kp, chan);
/* Simulate a disable by configuring for zero duty */
- writel(0, kp->base + DUTY_CYCLE_HIGH_OFFSET(chan));
- kona_pwmc_apply_settings(kp, chan);
-
- /* Wait for waveform to settle before gating off the clock */
- ndelay(400);
+ kona_pwmc_write_settings(kp, chan, 0, 0, 0);
+ kona_pwmc_set_polarity(chip, pwm, PWM_POLARITY_NORMAL);
+ kona_pwmc_set_trigger(kp, chan);
clk_disable_unprepare(kp->clk);
}
--
2.1.3
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