#include <linux/mutex.h>
#include <linux/of.h>
-struct pwm_device;
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;
/**
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_set_polarity - configure the polarity of a PWM signal
- */
-int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity);
+ pwm_get_state(pwm, &state);
+
+ return state.duty_cycle;
+}
static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm)
{
- return pwm ? pwm->polarity : PWM_POLARITY_NORMAL;
+ struct pwm_state state;
+
+ pwm_get_state(pwm, &state);
+
+ return state.polarity;
}
static inline void pwm_get_args(const struct pwm_device *pwm,
*args = pwm->args;
}
-static inline void pwm_apply_args(struct pwm_device *pwm)
-{
- pwm_set_period(pwm, pwm->args.period);
- pwm_set_polarity(pwm, pwm->args.polarity);
-}
-
/**
* struct pwm_ops - PWM controller operations
* @request: optional hook for requesting a PWM
* @set_polarity: configure the polarity of this PWM
* @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
*/
enum pwm_polarity polarity);
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
};
#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;
+
+ 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_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_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)
+{
+ /*
+ * 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.
+ *
+ * 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.
+ *
+ * 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);
+}
+
struct pwm_lookup {
struct list_head list;
const char *provider;
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