diff options
| -rw-r--r-- | Documentation/driver-api/pwm.rst | 4 | ||||
| -rw-r--r-- | drivers/pwm/core.c | 6 | ||||
| -rw-r--r-- | include/linux/pwm.h | 7 |
3 files changed, 16 insertions, 1 deletions
diff --git a/Documentation/driver-api/pwm.rst b/Documentation/driver-api/pwm.rst index a7ca4f58305a..750734a7f874 100644 --- a/Documentation/driver-api/pwm.rst +++ b/Documentation/driver-api/pwm.rst @@ -48,6 +48,10 @@ After being requested, a PWM has to be configured using:: This API controls both the PWM period/duty_cycle config and the enable/disable state. +There is also a usage_power setting: If set, the PWM driver is only required to +maintain the power output but has more freedom regarding signal form. +If supported by the driver, the signal can be optimized, for example to improve +EMI by phase shifting the individual channels of a chip. The pwm_config(), pwm_enable() and pwm_disable() functions are just wrappers around pwm_apply_state() and should not be used if the user wants to change diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index c165c5822703..a42999f877d2 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -536,7 +536,8 @@ int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state) if (state->period == pwm->state.period && state->duty_cycle == pwm->state.duty_cycle && state->polarity == pwm->state.polarity && - state->enabled == pwm->state.enabled) + state->enabled == pwm->state.enabled && + state->usage_power == pwm->state.usage_power) return 0; if (chip->ops->apply) { @@ -1241,6 +1242,9 @@ static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s) seq_printf(s, " polarity: %s", state.polarity ? "inverse" : "normal"); + if (state.usage_power) + seq_puts(s, " usage_power"); + seq_puts(s, "\n"); } } diff --git a/include/linux/pwm.h b/include/linux/pwm.h index 5bb90af4997e..5a73251d28e3 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -54,12 +54,17 @@ enum { * @duty_cycle: PWM duty cycle (in nanoseconds) * @polarity: PWM polarity * @enabled: PWM enabled status + * @usage_power: If set, the PWM driver is only required to maintain the power + * output but has more freedom regarding signal form. + * If supported, the signal can be optimized, for example to + * improve EMI by phase shifting individual channels. */ struct pwm_state { u64 period; u64 duty_cycle; enum pwm_polarity polarity; bool enabled; + bool usage_power; }; /** @@ -188,6 +193,7 @@ static inline void pwm_init_state(const struct pwm_device *pwm, state->period = args.period; state->polarity = args.polarity; state->duty_cycle = 0; + state->usage_power = false; } /** @@ -558,6 +564,7 @@ static inline void pwm_apply_args(struct pwm_device *pwm) state.enabled = false; state.polarity = pwm->args.polarity; state.period = pwm->args.period; + state.usage_power = false; pwm_apply_state(pwm, &state); } |