#include <linux/mutex.h>
#include <linux/of.h>
-struct pwm_device;
+struct pwm_capture;
struct seq_file;
-#if IS_ENABLED(CONFIG_PWM)
-/*
- * pwm_request - request a PWM device
- */
-struct pwm_device *pwm_request(int pwm_id, const char *label);
-
-/*
- * pwm_free - free a PWM device
- */
-void pwm_free(struct pwm_device *pwm);
-
-/*
- * pwm_config - change a PWM device configuration
- */
-int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns);
-
-/*
- * pwm_enable - start a PWM output toggling
- */
-int pwm_enable(struct pwm_device *pwm);
-
-/*
- * pwm_disable - stop a PWM output toggling
- */
-void pwm_disable(struct pwm_device *pwm);
-#else
-static inline struct pwm_device *pwm_request(int pwm_id, const char *label)
-{
- return ERR_PTR(-ENODEV);
-}
-
-static inline void pwm_free(struct pwm_device *pwm)
-{
-}
-
-static inline int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
-{
- return -EINVAL;
-}
-
-static inline int pwm_enable(struct pwm_device *pwm)
-{
- return -EINVAL;
-}
-
-static inline void pwm_disable(struct pwm_device *pwm)
-{
-}
-#endif
-
struct pwm_chip;
/**
PWM_POLARITY_INVERSED,
};
+/**
+ * struct pwm_args - board-dependent PWM arguments
+ * @period: reference period
+ * @polarity: reference polarity
+ *
+ * This structure describes board-dependent arguments attached to a PWM
+ * device. These arguments are usually retrieved from the PWM lookup table or
+ * device tree.
+ *
+ * Do not confuse this with the PWM state: PWM arguments represent the initial
+ * configuration that users want to use on this PWM device rather than the
+ * current PWM hardware state.
+ */
+struct pwm_args {
+ unsigned int period;
+ enum pwm_polarity polarity;
+};
+
enum {
PWMF_REQUESTED = 1 << 0,
- PWMF_ENABLED = 1 << 1,
- PWMF_EXPORTED = 1 << 2,
+ PWMF_EXPORTED = 1 << 1,
+};
+
+/*
+ * struct pwm_state - state of a PWM channel
+ * @period: PWM period (in nanoseconds)
+ * @duty_cycle: PWM duty cycle (in nanoseconds)
+ * @polarity: PWM polarity
+ * @enabled: PWM enabled status
+ */
+struct pwm_state {
+ unsigned int period;
+ unsigned int duty_cycle;
+ enum pwm_polarity polarity;
+ bool enabled;
};
/**
* @pwm: global index of the PWM device
* @chip: PWM chip providing this PWM device
* @chip_data: chip-private data associated with the PWM device
- * @lock: used to serialize accesses to the PWM device where necessary
- * @period: period of the PWM signal (in nanoseconds)
- * @duty_cycle: duty cycle of the PWM signal (in nanoseconds)
- * @polarity: polarity of the PWM signal
+ * @args: PWM arguments
+ * @state: curent PWM channel state
*/
struct pwm_device {
const char *label;
unsigned int pwm;
struct pwm_chip *chip;
void *chip_data;
- struct mutex lock;
- unsigned int period;
- unsigned int duty_cycle;
- enum pwm_polarity polarity;
+ struct pwm_args args;
+ struct pwm_state state;
};
+/**
+ * pwm_get_state() - retrieve the current PWM state
+ * @pwm: PWM device
+ * @state: state to fill with the current PWM state
+ */
+static inline void pwm_get_state(const struct pwm_device *pwm,
+ struct pwm_state *state)
+{
+ *state = pwm->state;
+}
+
static inline bool pwm_is_enabled(const struct pwm_device *pwm)
{
- return test_bit(PWMF_ENABLED, &pwm->flags);
+ struct pwm_state state;
+
+ pwm_get_state(pwm, &state);
+
+ return state.enabled;
}
static inline void pwm_set_period(struct pwm_device *pwm, unsigned int period)
{
if (pwm)
- pwm->period = period;
+ pwm->state.period = period;
}
static inline unsigned int pwm_get_period(const struct pwm_device *pwm)
{
- return pwm ? pwm->period : 0;
+ struct pwm_state state;
+
+ pwm_get_state(pwm, &state);
+
+ return state.period;
}
static inline void pwm_set_duty_cycle(struct pwm_device *pwm, unsigned int duty)
{
if (pwm)
- pwm->duty_cycle = duty;
+ pwm->state.duty_cycle = duty;
}
static inline unsigned int pwm_get_duty_cycle(const struct pwm_device *pwm)
{
- return pwm ? pwm->duty_cycle : 0;
+ struct pwm_state state;
+
+ pwm_get_state(pwm, &state);
+
+ return state.duty_cycle;
}
-/*
- * pwm_set_polarity - configure the polarity of a PWM signal
+static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm)
+{
+ struct pwm_state state;
+
+ pwm_get_state(pwm, &state);
+
+ return state.polarity;
+}
+
+static inline void pwm_get_args(const struct pwm_device *pwm,
+ struct pwm_args *args)
+{
+ *args = pwm->args;
+}
+
+/**
+ * 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.
*/
-int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity);
+static inline void pwm_init_state(const struct pwm_device *pwm,
+ struct pwm_state *state)
+{
+ struct pwm_args args;
-static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm)
+ /* 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)
{
- return pwm ? pwm->polarity : PWM_POLARITY_NORMAL;
+ 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;
}
/**
* @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
+ * should be adjusted with the real hardware config (if the
+ * approximate the period or duty_cycle value, state should
+ * reflect it)
+ * @get_state: get the current PWM state. This function is only
+ * called once per PWM device when the PWM chip is
+ * registered.
* @dbg_show: optional routine to show contents in debugfs
* @owner: helps prevent removal of modules exporting active PWMs
*/
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,
+ struct pwm_state *state);
+ void (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm,
+ struct pwm_state *state);
#ifdef CONFIG_DEBUG_FS
void (*dbg_show)(struct pwm_chip *chip, struct seq_file *s);
#endif
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);
+void pwm_free(struct pwm_device *pwm);
+int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state);
+int pwm_adjust_config(struct pwm_device *pwm);
+
+/**
+ * pwm_config() - change a PWM device configuration
+ * @pwm: PWM device
+ * @duty_ns: "on" time (in nanoseconds)
+ * @period_ns: duration (in nanoseconds) of one cycle
+ *
+ * Returns: 0 on success or a negative error code on failure.
+ */
+static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
+ int period_ns)
+{
+ struct pwm_state state;
+
+ 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;
+
+ state.duty_cycle = duty_ns;
+ state.period = period_ns;
+ return pwm_apply_state(pwm, &state);
+}
+
+/**
+ * pwm_set_polarity() - configure the polarity of a PWM signal
+ * @pwm: PWM device
+ * @polarity: new polarity of the PWM signal
+ *
+ * Note that the polarity cannot be configured while the PWM device is
+ * enabled.
+ *
+ * Returns: 0 on success or a negative error code on failure.
+ */
+static inline int pwm_set_polarity(struct pwm_device *pwm,
+ enum pwm_polarity polarity)
+{
+ struct pwm_state state;
+
+ if (!pwm)
+ return -EINVAL;
+
+ pwm_get_state(pwm, &state);
+ if (state.polarity == polarity)
+ return 0;
+
+ /*
+ * Changing the polarity of a running PWM without adjusting the
+ * dutycycle/period value is a bit risky (can introduce glitches).
+ * Return -EBUSY in this case.
+ * Note that this is allowed when using pwm_apply_state() because
+ * the user specifies all the parameters.
+ */
+ if (state.enabled)
+ return -EBUSY;
+
+ state.polarity = polarity;
+ return pwm_apply_state(pwm, &state);
+}
+
+/**
+ * pwm_enable() - start a PWM output toggling
+ * @pwm: PWM device
+ *
+ * Returns: 0 on success or a negative error code on failure.
+ */
+static inline int pwm_enable(struct pwm_device *pwm)
+{
+ struct pwm_state state;
+
+ if (!pwm)
+ return -EINVAL;
+
+ pwm_get_state(pwm, &state);
+ if (state.enabled)
+ return 0;
+
+ state.enabled = true;
+ return pwm_apply_state(pwm, &state);
+}
+
+/**
+ * pwm_disable() - stop a PWM output toggling
+ * @pwm: PWM device
+ */
+static inline void pwm_disable(struct pwm_device *pwm)
+{
+ struct pwm_state state;
+
+ if (!pwm)
+ return;
+
+ pwm_get_state(pwm, &state);
+ if (!state.enabled)
+ return;
+
+ state.enabled = false;
+ 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);
bool pwm_can_sleep(struct pwm_device *pwm);
#else
+static inline struct pwm_device *pwm_request(int pwm_id, const char *label)
+{
+ return ERR_PTR(-ENODEV);
+}
+
+static inline void pwm_free(struct pwm_device *pwm)
+{
+}
+
+static inline int pwm_apply_state(struct pwm_device *pwm,
+ const struct pwm_state *state)
+{
+ return -ENOTSUPP;
+}
+
+static inline int pwm_adjust_config(struct pwm_device *pwm)
+{
+ return -ENOTSUPP;
+}
+
+static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
+ int period_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)
+{
+ return -ENOTSUPP;
+}
+
+static inline int pwm_enable(struct pwm_device *pwm)
+{
+ return -EINVAL;
+}
+
+static inline void pwm_disable(struct pwm_device *pwm)
+{
+}
+
static inline int pwm_set_chip_data(struct pwm_device *pwm, void *data)
{
return -EINVAL;
}
#endif
+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.
+ * The problem is, polarity can only be changed when the PWM is
+ * disabled.
+ *
+ * PWM drivers supporting hardware readout may declare the PWM device
+ * as enabled, and prevent polarity setting, which changes from the
+ * existing behavior, where all PWM devices are declared as disabled
+ * at startup (even if they are actually enabled), thus authorizing
+ * polarity setting.
+ *
+ * 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().
+ */
+
+ state.enabled = false;
+ state.polarity = pwm->args.polarity;
+ state.period = pwm->args.period;
+
+ pwm_apply_state(pwm, &state);
+}
+
struct pwm_lookup {
struct list_head list;
const char *provider;
#ifdef CONFIG_PWM_SYSFS
void pwmchip_sysfs_export(struct pwm_chip *chip);
void pwmchip_sysfs_unexport(struct pwm_chip *chip);
+void pwmchip_sysfs_unexport_children(struct pwm_chip *chip);
#else
static inline void pwmchip_sysfs_export(struct pwm_chip *chip)
{
static inline void pwmchip_sysfs_unexport(struct pwm_chip *chip)
{
}
+
+static inline void pwmchip_sysfs_unexport_children(struct pwm_chip *chip)
+{
+}
#endif /* CONFIG_PWM_SYSFS */
#endif /* __LINUX_PWM_H */
projects / firefly-linux-kernel-4.4.55.git / blobdiff