Messages in this thread Patch in this message | | | From | Trevor Gamblin <> | Subject | [PATCH 1/2 v2] pwm: add duty offset support | Date | Tue, 9 Apr 2024 13:41:25 -0400 |
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Some PWM chips support a "phase" or "duty_offset" feature. This patch continues adding support for configuring this property in the PWM subsystem.
Functions duty_offset_show(), duty_offset_store(), and pwm_get_duty_offset() are added to match what exists for duty_cycle.
Handle duty_offset in the new pwmchip char device logic.
Add a check to disallow applying a state with both inversed polarity and a nonzero duty_offset.
Also add duty_offset to TP_printk in include/trace/events/pwm.h so that it is reported with other properties when using the event tracing pipe for debug.
Signed-off-by: Trevor Gamblin <tgamblin@baylibre.com> --- v2 changes: * Address feedback in v1: * Remove supports_offset flag in pwm_chip struct * Don't return EINVAL when state->duty_offset + state->duty_cycle > state->period in __pwm_apply(), since this is valid as long as neither is greater than state->period on its own * Add a check to disallow setting the PWM signal as inverse and a nonzero duty_offset at the same time in __pwm_apply(), with a comment explaining why
--- drivers/pwm/core.c | 82 +++++++++++++++++++++++++++++++++++--- include/linux/pwm.h | 15 +++++++ include/trace/events/pwm.h | 6 ++- 3 files changed, 95 insertions(+), 8 deletions(-)
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index 2745941a008b..0d12cce67be7 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -80,6 +80,7 @@ static void pwm_apply_debug(struct pwm_device *pwm, */ if (s1.enabled && s1.polarity != state->polarity) { s2.polarity = state->polarity; + s2.duty_offset = s1.duty_cycle; s2.duty_cycle = s1.period - s1.duty_cycle; s2.period = s1.period; s2.enabled = s1.enabled; @@ -121,6 +122,23 @@ static void pwm_apply_debug(struct pwm_device *pwm, state->duty_cycle, state->period, s2.duty_cycle, s2.period); + if (state->enabled && + last->polarity == state->polarity && + last->period == s2.period && + last->duty_offset > s2.duty_offset && + last->duty_offset <= state->duty_offset) + dev_warn(pwmchip_parent(chip), + ".apply didn't pick the best available duty offset (requested: %llu/%llu, applied: %llu/%llu, possible: %llu/%llu)\n", + state->duty_offset, state->period, + s2.duty_offset, s2.period, + last->duty_offset, last->period); + + if (state->enabled && state->duty_offset < s2.duty_offset) + dev_warn(pwmchip_parent(chip), + ".apply is supposed to round down duty_offset (requested: %llu/%llu, applied: %llu/%llu)\n", + state->duty_offset, state->period, + s2.duty_offset, s2.period); + if (!state->enabled && s2.enabled && s2.duty_cycle > 0) dev_warn(pwmchip_parent(chip), "requested disabled, but yielded enabled with duty > 0\n"); @@ -144,12 +162,13 @@ static void pwm_apply_debug(struct pwm_device *pwm, if (s1.enabled != last->enabled || s1.polarity != last->polarity || (s1.enabled && s1.period != last->period) || + (s1.enabled && s1.duty_offset != last->duty_offset) || (s1.enabled && s1.duty_cycle != last->duty_cycle)) { dev_err(pwmchip_parent(chip), - ".apply is not idempotent (ena=%d pol=%d %llu/%llu) -> (ena=%d pol=%d %llu/%llu)\n", + ".apply is not idempotent (ena=%d pol=%d %llu/%llu/%llu) -> (ena=%d pol=%d %llu/%llu/%llu)\n", s1.enabled, s1.polarity, s1.duty_cycle, s1.period, - last->enabled, last->polarity, last->duty_cycle, - last->period); + s1.duty_offset, last->enabled, last->polarity, + last->duty_cycle, last->period, last->duty_offset); } } @@ -164,13 +183,24 @@ static int __pwm_apply(struct pwm_device *pwm, const struct pwm_state *state) int err; if (!pwm || !state || !state->period || - state->duty_cycle > state->period) + state->duty_cycle > state->period || + state->duty_offset > state->period) return -EINVAL; chip = pwm->chip; + /* + * There is no need to set duty_offset with inverse polarity, + * since signals with duty_offset values greater than 0.5 * + * period can equivalently be represented by an inverted signal + * without offset. + */ + if (state->polarity == PWM_POLARITY_INVERSED && state->duty_offset) + return -EINVAL; + if (state->period == pwm->state.period && state->duty_cycle == pwm->state.duty_cycle && + state->duty_offset == pwm->state.duty_offset && state->polarity == pwm->state.polarity && state->enabled == pwm->state.enabled && state->usage_power == pwm->state.usage_power) @@ -292,10 +322,11 @@ int pwm_adjust_config(struct pwm_device *pwm) * been configured. * * In either case, we setup the new period and polarity, and assign a - * duty cycle of 0. + * duty cycle and offset of 0. */ if (!state.period) { state.duty_cycle = 0; + state.duty_offset = 0; state.period = pargs.period; state.polarity = pargs.polarity; @@ -617,6 +648,41 @@ static ssize_t duty_cycle_store(struct device *pwm_dev, return ret ? : size; } +static ssize_t duty_offset_show(struct device *pwm_dev, + struct device_attribute *attr, + char *buf) +{ + const struct pwm_device *pwm = pwm_from_dev(pwm_dev); + struct pwm_state state; + + pwm_get_state(pwm, &state); + + return sysfs_emit(buf, "%llu\n", state.duty_offset); +} + +static ssize_t duty_offset_store(struct device *pwm_dev, + struct device_attribute *attr, + const char *buf, size_t size) +{ + struct pwm_export *export = pwmexport_from_dev(pwm_dev); + struct pwm_device *pwm = export->pwm; + struct pwm_state state; + u64 val; + int ret; + + ret = kstrtou64(buf, 0, &val); + if (ret) + return ret; + + mutex_lock(&export->lock); + pwm_get_state(pwm, &state); + state.duty_offset = val; + ret = pwm_apply_might_sleep(pwm, &state); + mutex_unlock(&export->lock); + + return ret ? : size; +} + static ssize_t enable_show(struct device *pwm_dev, struct device_attribute *attr, char *buf) @@ -731,6 +797,7 @@ static ssize_t capture_show(struct device *pwm_dev, static DEVICE_ATTR_RW(period); static DEVICE_ATTR_RW(duty_cycle); +static DEVICE_ATTR_RW(duty_offset); static DEVICE_ATTR_RW(enable); static DEVICE_ATTR_RW(polarity); static DEVICE_ATTR_RO(capture); @@ -738,6 +805,7 @@ static DEVICE_ATTR_RO(capture); static struct attribute *pwm_attrs[] = { &dev_attr_period.attr, &dev_attr_duty_cycle.attr, + &dev_attr_duty_offset.attr, &dev_attr_enable.attr, &dev_attr_polarity.attr, &dev_attr_capture.attr, @@ -1290,7 +1358,7 @@ static long pwm_cdev_ioctl(struct file *file, unsigned int cmd, unsigned long ar if (state.enabled) { cstate.period = state.period; if (state.polarity == PWM_POLARITY_NORMAL) { - cstate.duty_offset = 0; + cstate.duty_offset = state.duty_offset; cstate.duty_cycle = state.duty_cycle; } else { cstate.duty_offset = state.duty_cycle; @@ -1356,6 +1424,7 @@ static long pwm_cdev_ioctl(struct file *file, unsigned int cmd, unsigned long ar state.period = cstate.period; state.polarity = PWM_POLARITY_NORMAL; state.duty_cycle = cstate.duty_cycle; + state.duty_offset = cstate.duty_offset; } else { state.enabled = false; } @@ -1991,6 +2060,7 @@ static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s) seq_printf(s, " period: %llu ns", state.period); seq_printf(s, " duty: %llu ns", state.duty_cycle); + seq_printf(s, " duty_offset: %llu ns", state.duty_offset); seq_printf(s, " polarity: %s", state.polarity ? "inverse" : "normal"); diff --git a/include/linux/pwm.h b/include/linux/pwm.h index a58db7011807..5a93212c58eb 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -51,6 +51,7 @@ enum { * struct pwm_state - state of a PWM channel * @period: PWM period (in nanoseconds) * @duty_cycle: PWM duty cycle (in nanoseconds) + * @duty_offset: PWM duty offset (in nanoseconds) * @polarity: PWM polarity * @enabled: PWM enabled status * @usage_power: If set, the PWM driver is only required to maintain the power @@ -61,6 +62,7 @@ enum { struct pwm_state { u64 period; u64 duty_cycle; + u64 duty_offset; enum pwm_polarity polarity; bool enabled; bool usage_power; @@ -130,6 +132,15 @@ static inline u64 pwm_get_duty_cycle(const struct pwm_device *pwm) return state.duty_cycle; } +static inline u64 pwm_get_duty_offset(const struct pwm_device *pwm) +{ + struct pwm_state state; + + pwm_get_state(pwm, &state); + + return state.duty_offset; +} + static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm) { struct pwm_state state; @@ -161,6 +172,9 @@ static inline void pwm_get_args(const struct pwm_device *pwm, * ->duty_cycle value exceed the pwm_args->period one, which would trigger * an error if the user calls pwm_apply_might_sleep() without adjusting ->duty_cycle * first. + * + * ->duty_offset is likewise set to zero to avoid inconsistent default + * states. */ static inline void pwm_init_state(const struct pwm_device *pwm, struct pwm_state *state) @@ -176,6 +190,7 @@ static inline void pwm_init_state(const struct pwm_device *pwm, state->period = args.period; state->polarity = args.polarity; state->duty_cycle = 0; + state->duty_offset = 0; state->usage_power = false; } diff --git a/include/trace/events/pwm.h b/include/trace/events/pwm.h index 12b35e4ff917..2d25ac5de816 100644 --- a/include/trace/events/pwm.h +++ b/include/trace/events/pwm.h @@ -18,6 +18,7 @@ DECLARE_EVENT_CLASS(pwm, __field(struct pwm_device *, pwm) __field(u64, period) __field(u64, duty_cycle) + __field(u64, duty_offset) __field(enum pwm_polarity, polarity) __field(bool, enabled) __field(int, err) @@ -27,13 +28,14 @@ DECLARE_EVENT_CLASS(pwm, __entry->pwm = pwm; __entry->period = state->period; __entry->duty_cycle = state->duty_cycle; + __entry->duty_offset = state->duty_offset; __entry->polarity = state->polarity; __entry->enabled = state->enabled; __entry->err = err; ), - TP_printk("%p: period=%llu duty_cycle=%llu polarity=%d enabled=%d err=%d", - __entry->pwm, __entry->period, __entry->duty_cycle, + TP_printk("%p: period=%llu duty_cycle=%llu duty_offset=%llu polarity=%d enabled=%d err=%d", + __entry->pwm, __entry->period, __entry->duty_cycle, __entry->duty_offset, __entry->polarity, __entry->enabled, __entry->err) ); -- 2.44.0
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