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 <zhangq...@rock-chips.com>
Signed-off-by: Kever Yang <kever.y...@rock-chips.com>
Acked-by: Simon Glass <s...@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);
--
1.9.1
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