forked from mirrors/linux
pwm: Add core infrastructure to allow atomic updates
Add an ->apply() method to the pwm_ops struct to allow PWM drivers to implement atomic updates. This method is preferred over the ->enable(), ->disable() and ->config() methods if available. Add the pwm_apply_state() function to the PWM user API. Note that the pwm_apply_state() does not guarantee the atomicity of the update operation, it all depends on the availability and implementation of the ->apply() method. pwm_enable/disable/set_polarity/config() are now implemented as wrappers around the pwm_apply_state() function. pwm_adjust_config() is allowing smooth handover between the bootloader and the kernel. This function tries to adapt the current PWM state to the PWM arguments coming from a PWM lookup table or a DT definition without changing the duty_cycle/period proportion. Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> [thierry.reding@gmail.com: fix a couple of typos] Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This commit is contained in:
Boris Brezillon
Thierry Reding
parent
15fa8a43c1
commit
5ec803edcb
2 changed files with 314 additions and 164 deletions
|
|
@ -226,6 +226,19 @@ void *pwm_get_chip_data(struct pwm_device *pwm)
|
|||
}
|
||||
EXPORT_SYMBOL_GPL(pwm_get_chip_data);
|
||||
|
||||
static bool pwm_ops_check(const struct pwm_ops *ops)
|
||||
{
|
||||
/* driver supports legacy, non-atomic operation */
|
||||
if (ops->config && ops->enable && ops->disable)
|
||||
return true;
|
||||
|
||||
/* driver supports atomic operation */
|
||||
if (ops->apply)
|
||||
return true;
|
||||
|
||||
return false;
|
||||
}
|
||||
|
||||
/**
|
||||
* pwmchip_add_with_polarity() - register a new PWM chip
|
||||
* @chip: the PWM chip to add
|
||||
|
|
@ -244,8 +257,10 @@ int pwmchip_add_with_polarity(struct pwm_chip *chip,
|
|||
unsigned int i;
|
||||
int ret;
|
||||
|
||||
if (!chip || !chip->dev || !chip->ops || !chip->ops->config ||
|
||||
!chip->ops->enable || !chip->ops->disable || !chip->npwm)
|
||||
if (!chip || !chip->dev || !chip->ops || !chip->npwm)
|
||||
return -EINVAL;
|
||||
|
||||
if (!pwm_ops_check(chip->ops))
|
||||
return -EINVAL;
|
||||
|
||||
mutex_lock(&pwm_lock);
|
||||
|
|
@ -431,102 +446,138 @@ void pwm_free(struct pwm_device *pwm)
|
|||
EXPORT_SYMBOL_GPL(pwm_free);
|
||||
|
||||
/**
|
||||
* pwm_config() - change a PWM device configuration
|
||||
* pwm_apply_state() - atomically apply a new state to a PWM device
|
||||
* @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.
|
||||
* @state: new state to apply. This can be adjusted by the PWM driver
|
||||
* if the requested config is not achievable, for example,
|
||||
* ->duty_cycle and ->period might be approximated.
|
||||
*/
|
||||
int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
|
||||
int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state)
|
||||
{
|
||||
int err;
|
||||
|
||||
if (!pwm || duty_ns < 0 || period_ns <= 0 || duty_ns > period_ns)
|
||||
if (!pwm)
|
||||
return -EINVAL;
|
||||
|
||||
err = pwm->chip->ops->config(pwm->chip, pwm, duty_ns, period_ns);
|
||||
if (!memcmp(state, &pwm->state, sizeof(*state)))
|
||||
return 0;
|
||||
|
||||
if (pwm->chip->ops->apply) {
|
||||
err = pwm->chip->ops->apply(pwm->chip, pwm, state);
|
||||
if (err)
|
||||
return err;
|
||||
|
||||
pwm->state.duty_cycle = duty_ns;
|
||||
pwm->state.period = period_ns;
|
||||
|
||||
return 0;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(pwm_config);
|
||||
|
||||
/**
|
||||
* 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.
|
||||
pwm->state = *state;
|
||||
} else {
|
||||
/*
|
||||
* FIXME: restore the initial state in case of error.
|
||||
*/
|
||||
int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity)
|
||||
{
|
||||
int err;
|
||||
|
||||
if (!pwm || !pwm->chip->ops)
|
||||
return -EINVAL;
|
||||
|
||||
if (state->polarity != pwm->state.polarity) {
|
||||
if (!pwm->chip->ops->set_polarity)
|
||||
return -ENOSYS;
|
||||
return -ENOTSUPP;
|
||||
|
||||
if (pwm_is_enabled(pwm))
|
||||
return -EBUSY;
|
||||
|
||||
err = pwm->chip->ops->set_polarity(pwm->chip, pwm, polarity);
|
||||
if (err)
|
||||
return err;
|
||||
|
||||
pwm->state.polarity = polarity;
|
||||
|
||||
return 0;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(pwm_set_polarity);
|
||||
|
||||
/**
|
||||
* pwm_enable() - start a PWM output toggling
|
||||
* @pwm: PWM device
|
||||
*
|
||||
* Returns: 0 on success or a negative error code on failure.
|
||||
/*
|
||||
* Changing the polarity of a running PWM is
|
||||
* only allowed when the PWM driver implements
|
||||
* ->apply().
|
||||
*/
|
||||
int pwm_enable(struct pwm_device *pwm)
|
||||
{
|
||||
int err = 0;
|
||||
|
||||
if (!pwm)
|
||||
return -EINVAL;
|
||||
|
||||
if (!pwm_is_enabled(pwm)) {
|
||||
err = pwm->chip->ops->enable(pwm->chip, pwm);
|
||||
if (!err)
|
||||
pwm->state.enabled = true;
|
||||
}
|
||||
|
||||
return err;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(pwm_enable);
|
||||
|
||||
/**
|
||||
* pwm_disable() - stop a PWM output toggling
|
||||
* @pwm: PWM device
|
||||
*/
|
||||
void pwm_disable(struct pwm_device *pwm)
|
||||
{
|
||||
if (!pwm)
|
||||
return;
|
||||
|
||||
if (pwm_is_enabled(pwm)) {
|
||||
if (pwm->state.enabled) {
|
||||
pwm->chip->ops->disable(pwm->chip, pwm);
|
||||
pwm->state.enabled = false;
|
||||
}
|
||||
|
||||
err = pwm->chip->ops->set_polarity(pwm->chip, pwm,
|
||||
state->polarity);
|
||||
if (err)
|
||||
return err;
|
||||
|
||||
pwm->state.polarity = state->polarity;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(pwm_disable);
|
||||
|
||||
if (state->period != pwm->state.period ||
|
||||
state->duty_cycle != pwm->state.duty_cycle) {
|
||||
err = pwm->chip->ops->config(pwm->chip, pwm,
|
||||
state->duty_cycle,
|
||||
state->period);
|
||||
if (err)
|
||||
return err;
|
||||
|
||||
pwm->state.duty_cycle = state->duty_cycle;
|
||||
pwm->state.period = state->period;
|
||||
}
|
||||
|
||||
if (state->enabled != pwm->state.enabled) {
|
||||
if (state->enabled) {
|
||||
err = pwm->chip->ops->enable(pwm->chip, pwm);
|
||||
if (err)
|
||||
return err;
|
||||
} else {
|
||||
pwm->chip->ops->disable(pwm->chip, pwm);
|
||||
}
|
||||
|
||||
pwm->state.enabled = state->enabled;
|
||||
}
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(pwm_apply_state);
|
||||
|
||||
/**
|
||||
* pwm_adjust_config() - adjust the current PWM config to the PWM arguments
|
||||
* @pwm: PWM device
|
||||
*
|
||||
* This function will adjust the PWM config to the PWM arguments provided
|
||||
* by the DT or PWM lookup table. This is particularly useful to adapt
|
||||
* the bootloader config to the Linux one.
|
||||
*/
|
||||
int pwm_adjust_config(struct pwm_device *pwm)
|
||||
{
|
||||
struct pwm_state state;
|
||||
struct pwm_args pargs;
|
||||
|
||||
pwm_get_args(pwm, &pargs);
|
||||
pwm_get_state(pwm, &state);
|
||||
|
||||
/*
|
||||
* If the current period is zero it means that either the PWM driver
|
||||
* does not support initial state retrieval or the PWM has not yet
|
||||
* been configured.
|
||||
*
|
||||
* In either case, we setup the new period and polarity, and assign a
|
||||
* duty cycle of 0.
|
||||
*/
|
||||
if (!state.period) {
|
||||
state.duty_cycle = 0;
|
||||
state.period = pargs.period;
|
||||
state.polarity = pargs.polarity;
|
||||
|
||||
return pwm_apply_state(pwm, &state);
|
||||
}
|
||||
|
||||
/*
|
||||
* Adjust the PWM duty cycle/period based on the period value provided
|
||||
* in PWM args.
|
||||
*/
|
||||
if (pargs.period != state.period) {
|
||||
u64 dutycycle = (u64)state.duty_cycle * pargs.period;
|
||||
|
||||
do_div(dutycycle, state.period);
|
||||
state.duty_cycle = dutycycle;
|
||||
state.period = pargs.period;
|
||||
}
|
||||
|
||||
/*
|
||||
* If the polarity changed, we should also change the duty cycle.
|
||||
*/
|
||||
if (pargs.polarity != state.polarity) {
|
||||
state.polarity = pargs.polarity;
|
||||
state.duty_cycle = state.period - state.duty_cycle;
|
||||
}
|
||||
|
||||
return pwm_apply_state(pwm, &state);
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(pwm_adjust_config);
|
||||
|
||||
static struct pwm_chip *of_node_to_pwmchip(struct device_node *np)
|
||||
{
|
||||
|
|
|
|||
|
|
@ -5,59 +5,7 @@
|
|||
#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;
|
||||
|
||||
/**
|
||||
|
|
@ -184,11 +132,6 @@ static inline unsigned int pwm_get_duty_cycle(const struct pwm_device *pwm)
|
|||
return state.duty_cycle;
|
||||
}
|
||||
|
||||
/*
|
||||
* pwm_set_polarity - configure the polarity of a PWM signal
|
||||
*/
|
||||
int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity);
|
||||
|
||||
static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm)
|
||||
{
|
||||
struct pwm_state state;
|
||||
|
|
@ -204,34 +147,6 @@ 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 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_ops - PWM controller operations
|
||||
* @request: optional hook for requesting a PWM
|
||||
|
|
@ -240,6 +155,10 @@ static inline void pwm_apply_args(struct pwm_device *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.
|
||||
|
|
@ -255,6 +174,8 @@ struct pwm_ops {
|
|||
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
|
||||
|
|
@ -292,6 +213,115 @@ struct pwm_chip {
|
|||
};
|
||||
|
||||
#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);
|
||||
|
||||
|
|
@ -317,6 +347,47 @@ void devm_pwm_put(struct device *dev, 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;
|
||||
|
|
@ -388,6 +459,34 @@ static inline bool pwm_can_sleep(struct pwm_device *pwm)
|
|||
}
|
||||
#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;
|
||||
|
|
|
|||
Loading…
Reference in a new issue