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path: root/drivers/pwm/pwm-cros-ec.c
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Diffstat (limited to 'drivers/pwm/pwm-cros-ec.c')
-rw-r--r--drivers/pwm/pwm-cros-ec.c58
1 files changed, 54 insertions, 4 deletions
diff --git a/drivers/pwm/pwm-cros-ec.c b/drivers/pwm/pwm-cros-ec.c
index 89497448d217..09c08dee099e 100644
--- a/drivers/pwm/pwm-cros-ec.c
+++ b/drivers/pwm/pwm-cros-ec.c
@@ -25,11 +25,39 @@ struct cros_ec_pwm_device {
struct pwm_chip chip;
};
+/**
+ * struct cros_ec_pwm - per-PWM driver data
+ * @duty_cycle: cached duty cycle
+ */
+struct cros_ec_pwm {
+ u16 duty_cycle;
+};
+
static inline struct cros_ec_pwm_device *pwm_to_cros_ec_pwm(struct pwm_chip *c)
{
return container_of(c, struct cros_ec_pwm_device, chip);
}
+static int cros_ec_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct cros_ec_pwm *channel;
+
+ channel = kzalloc(sizeof(*channel), GFP_KERNEL);
+ if (!channel)
+ return -ENOMEM;
+
+ pwm_set_chip_data(pwm, channel);
+
+ return 0;
+}
+
+static void cros_ec_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
+
+ kfree(channel);
+}
+
static int cros_ec_pwm_set_duty(struct cros_ec_device *ec, u8 index, u16 duty)
{
struct {
@@ -96,7 +124,9 @@ static int cros_ec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
const struct pwm_state *state)
{
struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip);
- int duty_cycle;
+ struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
+ u16 duty_cycle;
+ int ret;
/* The EC won't let us change the period */
if (state->period != EC_PWM_MAX_DUTY)
@@ -108,13 +138,20 @@ static int cros_ec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
*/
duty_cycle = state->enabled ? state->duty_cycle : 0;
- return cros_ec_pwm_set_duty(ec_pwm->ec, pwm->hwpwm, duty_cycle);
+ ret = cros_ec_pwm_set_duty(ec_pwm->ec, pwm->hwpwm, duty_cycle);
+ if (ret < 0)
+ return ret;
+
+ channel->duty_cycle = state->duty_cycle;
+
+ return 0;
}
static void cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
struct pwm_state *state)
{
struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip);
+ struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
int ret;
ret = cros_ec_pwm_get_duty(ec_pwm->ec, pwm->hwpwm);
@@ -126,8 +163,19 @@ static void cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
state->enabled = (ret > 0);
state->period = EC_PWM_MAX_DUTY;
- /* Note that "disabled" and "duty cycle == 0" are treated the same */
- state->duty_cycle = ret;
+ /*
+ * Note that "disabled" and "duty cycle == 0" are treated the same. If
+ * the cached duty cycle is not zero, used the cached duty cycle. This
+ * ensures that the configured duty cycle is kept across a disable and
+ * enable operation and avoids potentially confusing consumers.
+ *
+ * For the case of the initial hardware readout, channel->duty_cycle
+ * will be 0 and the actual duty cycle read from the EC is used.
+ */
+ if (ret == 0 && channel->duty_cycle > 0)
+ state->duty_cycle = channel->duty_cycle;
+ else
+ state->duty_cycle = ret;
}
static struct pwm_device *
@@ -149,6 +197,8 @@ cros_ec_pwm_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
}
static const struct pwm_ops cros_ec_pwm_ops = {
+ .request = cros_ec_pwm_request,
+ .free = cros_ec_pwm_free,
.get_state = cros_ec_pwm_get_state,
.apply = cros_ec_pwm_apply,
.owner = THIS_MODULE,