The latest kernel PWM drivers enable the polarity settings. When system run from U-Boot to kerenl, if there are differences in polarity set or duty cycle, the PMW will re-init: close -> set polarity and duty cycle -> enable the PWM. The power supply controled by pwm regulator may have voltage shaking, which lead to the system not stable.
Signed-off-by: Elaine Zhang zhangqing@rock-chips.com Signed-off-by: Kever Yang kever.yang@rock-chips.com Acked-by: Simon Glass sjg@chromium.org ---
Changes in v4: - Split patch into uclass and rockchip patch
Changes in v3: - use bool type for polarity
Changes in v2: - use pwm_set_invert() instead of pwm_set_init() - add comment for polarity
drivers/power/regulator/pwm_regulator.c | 16 ++++++++++++++-- drivers/pwm/pwm-uclass.c | 10 ++++++++++ include/pwm.h | 19 +++++++++++++++++++ 3 files changed, 43 insertions(+), 2 deletions(-)
diff --git a/drivers/power/regulator/pwm_regulator.c b/drivers/power/regulator/pwm_regulator.c index 4875238..a6c9fcc 100644 --- a/drivers/power/regulator/pwm_regulator.c +++ b/drivers/power/regulator/pwm_regulator.c @@ -24,6 +24,12 @@ struct pwm_regulator_info { int pwm_id; /* the period of one PWM cycle */ int period_ns; + /* + * the polarity of one PWM + * 0: normal polarity + * 1: inverted polarity + */ + bool polarity; struct udevice *pwm; /* initialize voltage of regulator */ unsigned int init_voltage; @@ -49,7 +55,7 @@ static int pwm_voltage_to_duty_cycle_percentage(struct udevice *dev, int req_uV) int max_uV = priv->max_voltage; int diff = max_uV - min_uV;
- return 100 - (((req_uV * 100) - (min_uV * 100)) / diff); + return ((req_uV * 100) - (min_uV * 100)) / diff; }
static int pwm_regulator_get_voltage(struct udevice *dev) @@ -67,6 +73,12 @@ static int pwm_regulator_set_voltage(struct udevice *dev, int uvolt)
duty_cycle = pwm_voltage_to_duty_cycle_percentage(dev, uvolt);
+ ret = pwm_set_invert(priv->pwm, priv->pwm_id, priv->polarity); + if (ret) { + dev_err(dev, "Failed to init PWM\n"); + return ret; + } + ret = pwm_set_config(priv->pwm, priv->pwm_id, (priv->period_ns / 100) * duty_cycle, priv->period_ns); if (ret) { @@ -97,9 +109,9 @@ static int pwm_regulator_ofdata_to_platdata(struct udevice *dev) debug("%s: Cannot get PWM phandle: ret=%d\n", __func__, ret); return ret; } - /* TODO: pwm_id here from device tree if needed */
priv->period_ns = args.args[1]; + priv->polarity = args.args[2];
priv->init_voltage = fdtdec_get_int(blob, node, "regulator-init-microvolt", -1); diff --git a/drivers/pwm/pwm-uclass.c b/drivers/pwm/pwm-uclass.c index c2200af..69051fe 100644 --- a/drivers/pwm/pwm-uclass.c +++ b/drivers/pwm/pwm-uclass.c @@ -9,6 +9,16 @@ #include <dm.h> #include <pwm.h>
+int pwm_set_invert(struct udevice *dev, uint channel, bool polarity) +{ + struct pwm_ops *ops = pwm_get_ops(dev); + + if (!ops->set_invert) + return -ENOSYS; + + return ops->set_invert(dev, channel, polarity); +} + int pwm_set_config(struct udevice *dev, uint channel, uint period_ns, uint duty_ns) { diff --git a/include/pwm.h b/include/pwm.h index 851915e..ebee227 100644 --- a/include/pwm.h +++ b/include/pwm.h @@ -34,6 +34,15 @@ struct pwm_ops { * @return 0 if OK, -ve on error */ int (*set_enable)(struct udevice *dev, uint channel, bool enable); + /** + * set_invert() - Set the PWM invert + * + * @dev: PWM device to update + * @channel: PWM channel to update + * @polarity: true to invert, false to keep normal polarity + * @return 0 if OK, -ve on error + */ + int (*set_invert)(struct udevice *dev, uint channel, bool polarity); };
#define pwm_get_ops(dev) ((struct pwm_ops *)(dev)->driver->ops) @@ -60,6 +69,16 @@ int pwm_set_config(struct udevice *dev, uint channel, uint period_ns, */ int pwm_set_enable(struct udevice *dev, uint channel, bool enable);
+/** + * pwm_set_invert() - Set pwm default polarity + * + * @dev: PWM device to update + * @channel: PWM channel to update + * @polarity: true to invert, false to keep normal polarity + * @return 0 if OK, -ve on error + */ +int pwm_set_invert(struct udevice *dev, uint channel, bool polarity); + /* Legacy interface */ #ifndef CONFIG_DM_PWM int pwm_init (int pwm_id, int div, int invert);