diff options
| -rw-r--r-- | Documentation/ABI/testing/sysfs-class-pwm | 9 | ||||
| -rw-r--r-- | drivers/pwm/core.c | 30 | ||||
| -rw-r--r-- | drivers/pwm/pwm-atmel-hlcdc.c | 2 | ||||
| -rw-r--r-- | drivers/pwm/sysfs.c | 19 | ||||
| -rw-r--r-- | include/linux/pwm.h | 132 |
5 files changed, 182 insertions, 10 deletions
diff --git a/Documentation/ABI/testing/sysfs-class-pwm b/Documentation/ABI/testing/sysfs-class-pwm index c479d77b67c5..c20e61354561 100644 --- a/Documentation/ABI/testing/sysfs-class-pwm +++ b/Documentation/ABI/testing/sysfs-class-pwm @@ -77,3 +77,12 @@ Description: Enable/disable the PWM signal. 0 is disabled 1 is enabled + +What: /sys/class/pwm/pwmchipN/pwmX/capture +Date: June 2016 +KernelVersion: 4.8 +Contact: Lee Jones <[email protected]> +Description: + Capture information about a PWM signal. The output format is a + pair unsigned integers (period and duty cycle), separated by a + single space. diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index dba3843c53b8..0dbd29e287db 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -457,7 +457,8 @@ int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state) { int err; - if (!pwm) + if (!pwm || !state || !state->period || + state->duty_cycle > state->period) return -EINVAL; if (!memcmp(state, &pwm->state, sizeof(*state))) @@ -525,6 +526,33 @@ int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state) EXPORT_SYMBOL_GPL(pwm_apply_state); /** + * pwm_capture() - capture and report a PWM signal + * @pwm: PWM device + * @result: structure to fill with capture result + * @timeout: time to wait, in milliseconds, before giving up on capture + * + * Returns: 0 on success or a negative error code on failure. + */ +int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result, + unsigned long timeout) +{ + int err; + + if (!pwm || !pwm->chip->ops) + return -EINVAL; + + if (!pwm->chip->ops->capture) + return -ENOSYS; + + mutex_lock(&pwm_lock); + err = pwm->chip->ops->capture(pwm->chip, pwm, result, timeout); + mutex_unlock(&pwm_lock); + + return err; +} +EXPORT_SYMBOL_GPL(pwm_capture); + +/** * pwm_adjust_config() - adjust the current PWM config to the PWM arguments * @pwm: PWM device * diff --git a/drivers/pwm/pwm-atmel-hlcdc.c b/drivers/pwm/pwm-atmel-hlcdc.c index f994c7eaf41c..14fc011faa32 100644 --- a/drivers/pwm/pwm-atmel-hlcdc.c +++ b/drivers/pwm/pwm-atmel-hlcdc.c @@ -272,7 +272,7 @@ static int atmel_hlcdc_pwm_probe(struct platform_device *pdev) chip->chip.of_pwm_n_cells = 3; chip->chip.can_sleep = 1; - ret = pwmchip_add(&chip->chip); + ret = pwmchip_add_with_polarity(&chip->chip, PWM_POLARITY_INVERSED); if (ret) { clk_disable_unprepare(hlcdc->periph_clk); return ret; diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c index d98599249a05..18ed725594c3 100644 --- a/drivers/pwm/sysfs.c +++ b/drivers/pwm/sysfs.c @@ -152,7 +152,7 @@ static ssize_t enable_store(struct device *child, goto unlock; } - pwm_apply_state(pwm, &state); + ret = pwm_apply_state(pwm, &state); unlock: mutex_unlock(&export->lock); @@ -208,16 +208,33 @@ static ssize_t polarity_store(struct device *child, return ret ? : size; } +static ssize_t capture_show(struct device *child, + struct device_attribute *attr, + char *buf) +{ + struct pwm_device *pwm = child_to_pwm_device(child); + struct pwm_capture result; + int ret; + + ret = pwm_capture(pwm, &result, jiffies_to_msecs(HZ)); + if (ret) + return ret; + + return sprintf(buf, "%u %u\n", result.period, result.duty_cycle); +} + static DEVICE_ATTR_RW(period); static DEVICE_ATTR_RW(duty_cycle); static DEVICE_ATTR_RW(enable); static DEVICE_ATTR_RW(polarity); +static DEVICE_ATTR_RO(capture); static struct attribute *pwm_attrs[] = { &dev_attr_period.attr, &dev_attr_duty_cycle.attr, &dev_attr_enable.attr, &dev_attr_polarity.attr, + &dev_attr_capture.attr, NULL }; ATTRIBUTE_GROUPS(pwm); diff --git a/include/linux/pwm.h b/include/linux/pwm.h index 17018f3c066e..f1bbae014889 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -5,7 +5,9 @@ #include <linux/mutex.h> #include <linux/of.h> +struct pwm_capture; struct seq_file; + struct pwm_chip; /** @@ -148,11 +150,100 @@ static inline void pwm_get_args(const struct pwm_device *pwm, } /** + * pwm_init_state() - prepare a new state to be applied with pwm_apply_state() + * @pwm: PWM device + * @state: state to fill with the prepared PWM state + * + * This functions prepares a state that can later be tweaked and applied + * to the PWM device with pwm_apply_state(). This is a convenient function + * that first retrieves the current PWM state and the replaces the period + * and polarity fields with the reference values defined in pwm->args. + * Once the function returns, you can adjust the ->enabled and ->duty_cycle + * fields according to your needs before calling pwm_apply_state(). + * + * ->duty_cycle is initially set to zero to avoid cases where the current + * ->duty_cycle value exceed the pwm_args->period one, which would trigger + * an error if the user calls pwm_apply_state() without adjusting ->duty_cycle + * first. + */ +static inline void pwm_init_state(const struct pwm_device *pwm, + struct pwm_state *state) +{ + struct pwm_args args; + + /* First get the current state. */ + pwm_get_state(pwm, state); + + /* Then fill it with the reference config */ + pwm_get_args(pwm, &args); + + state->period = args.period; + state->polarity = args.polarity; + state->duty_cycle = 0; +} + +/** + * pwm_get_relative_duty_cycle() - Get a relative duty cycle value + * @state: PWM state to extract the duty cycle from + * @scale: target scale of the relative duty cycle + * + * This functions converts the absolute duty cycle stored in @state (expressed + * in nanosecond) into a value relative to the period. + * + * For example if you want to get the duty_cycle expressed in percent, call: + * + * pwm_get_state(pwm, &state); + * duty = pwm_get_relative_duty_cycle(&state, 100); + */ +static inline unsigned int +pwm_get_relative_duty_cycle(const struct pwm_state *state, unsigned int scale) +{ + if (!state->period) + return 0; + + return DIV_ROUND_CLOSEST_ULL((u64)state->duty_cycle * scale, + state->period); +} + +/** + * pwm_set_relative_duty_cycle() - Set a relative duty cycle value + * @state: PWM state to fill + * @duty_cycle: relative duty cycle value + * @scale: scale in which @duty_cycle is expressed + * + * This functions converts a relative into an absolute duty cycle (expressed + * in nanoseconds), and puts the result in state->duty_cycle. + * + * For example if you want to configure a 50% duty cycle, call: + * + * pwm_init_state(pwm, &state); + * pwm_set_relative_duty_cycle(&state, 50, 100); + * pwm_apply_state(pwm, &state); + * + * This functions returns -EINVAL if @duty_cycle and/or @scale are + * inconsistent (@scale == 0 or @duty_cycle > @scale). + */ +static inline int +pwm_set_relative_duty_cycle(struct pwm_state *state, unsigned int duty_cycle, + unsigned int scale) +{ + if (!scale || duty_cycle > scale) + return -EINVAL; + + state->duty_cycle = DIV_ROUND_CLOSEST_ULL((u64)duty_cycle * + state->period, + scale); + + return 0; +} + +/** * struct pwm_ops - PWM controller operations * @request: optional hook for requesting a PWM * @free: optional hook for freeing a PWM * @config: configure duty cycles and period length for this PWM * @set_polarity: configure the polarity of this PWM + * @capture: capture and report PWM signal * @enable: enable PWM output toggling * @disable: disable PWM output toggling * @apply: atomically apply a new PWM config. The state argument @@ -172,6 +263,8 @@ struct pwm_ops { int duty_ns, int period_ns); int (*set_polarity)(struct pwm_chip *chip, struct pwm_device *pwm, enum pwm_polarity polarity); + int (*capture)(struct pwm_chip *chip, struct pwm_device *pwm, + struct pwm_capture *result, unsigned long timeout); int (*enable)(struct pwm_chip *chip, struct pwm_device *pwm); void (*disable)(struct pwm_chip *chip, struct pwm_device *pwm); int (*apply)(struct pwm_chip *chip, struct pwm_device *pwm, @@ -212,6 +305,16 @@ struct pwm_chip { bool can_sleep; }; +/** + * struct pwm_capture - PWM capture data + * @period: period of the PWM signal (in nanoseconds) + * @duty_cycle: duty cycle of the PWM signal (in nanoseconds) + */ +struct pwm_capture { + unsigned int period; + unsigned int duty_cycle; +}; + #if IS_ENABLED(CONFIG_PWM) /* PWM user APIs */ struct pwm_device *pwm_request(int pwm_id, const char *label); @@ -235,6 +338,9 @@ static inline int pwm_config(struct pwm_device *pwm, int duty_ns, if (!pwm) return -EINVAL; + if (duty_ns < 0 || period_ns < 0) + return -EINVAL; + pwm_get_state(pwm, &state); if (state.duty_cycle == duty_ns && state.period == period_ns) return 0; @@ -320,8 +426,9 @@ static inline void pwm_disable(struct pwm_device *pwm) pwm_apply_state(pwm, &state); } - /* PWM provider APIs */ +int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result, + unsigned long timeout); int pwm_set_chip_data(struct pwm_device *pwm, void *data); void *pwm_get_chip_data(struct pwm_device *pwm); @@ -373,6 +480,13 @@ static inline int pwm_config(struct pwm_device *pwm, int duty_ns, return -EINVAL; } +static inline int pwm_capture(struct pwm_device *pwm, + struct pwm_capture *result, + unsigned long timeout) +{ + return -EINVAL; +} + static inline int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity) { @@ -461,6 +575,8 @@ static inline bool pwm_can_sleep(struct pwm_device *pwm) static inline void pwm_apply_args(struct pwm_device *pwm) { + struct pwm_state state = { }; + /* * PWM users calling pwm_apply_args() expect to have a fresh config * where the polarity and period are set according to pwm_args info. @@ -473,18 +589,20 @@ static inline void pwm_apply_args(struct pwm_device *pwm) * at startup (even if they are actually enabled), thus authorizing * polarity setting. * - * Instead of setting ->enabled to false, we call pwm_disable() - * before pwm_set_polarity() to ensure that everything is configured - * as expected, and the PWM is really disabled when the user request - * it. + * To fulfill this requirement, we apply a new state which disables + * the PWM device and set the reference period and polarity config. * * Note that PWM users requiring a smooth handover between the * bootloader and the kernel (like critical regulators controlled by * PWM devices) will have to switch to the atomic API and avoid calling * pwm_apply_args(). */ - pwm_disable(pwm); - pwm_set_polarity(pwm, pwm->args.polarity); + + state.enabled = false; + state.polarity = pwm->args.polarity; + state.period = pwm->args.period; + + pwm_apply_state(pwm, &state); } struct pwm_lookup { |