After being requested, a PWM has to be configured using:
-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);
-To start/stop toggling the PWM output use pwm_enable()/pwm_disable().
+This API controls both the PWM period/duty_cycle config and the
+enable/disable state.
+
+The pwm_config(), pwm_enable() and pwm_disable() functions are just wrappers
+around pwm_apply_state() and should not be used if the user wants to change
+several parameter at once. For example, if you see pwm_config() and
+pwm_{enable,disable}() calls in the same function, this probably means you
+should switch to pwm_apply_state().
+
+The PWM user API also allows one to query the PWM state with pwm_get_state().
+
+In addition to the PWM state, the PWM API also exposes PWM arguments, which
+are the reference PWM config one should use on this PWM.
+PWM arguments are usually platform-specific and allows the PWM user to only
+care about dutycycle relatively to the full period (like, duty = 50% of the
+period). struct pwm_args contains 2 fields (period and polarity) and should
+be used to set the initial PWM config (usually done in the probe function
+of the PWM user). PWM arguments are retrieved with pwm_get_args().
Using PWMs with the sysfs interface
-----------------------------------
polarity starts low for the duration of the duty cycle and goes high for the
remainder of the period.
+Drivers are encouraged to implement ->apply() instead of the legacy
+->enable(), ->disable() and ->config() methods. Doing that should provide
+atomicity in the PWM config workflow, which is required when the PWM controls
+a critical device (like a regulator).
+
+The implementation of ->get_state() (a method used to retrieve initial PWM
+state) is also encouraged for the same reason: letting the PWM user know
+about the current PWM state would allow him to avoid glitches.
+
Locking
-------
return PTR_ERR(lcd_pwm);
}
+ /*
+ * FIXME: pwm_apply_args() should be removed when switching to
+ * the atomic PWM API.
+ */
+ pwm_apply_args(lcd_pwm);
+
rx1950_lcd_power(1);
rx1950_bl_power(1);
struct clk_init_data init;
struct clk_pwm *clk_pwm;
struct pwm_device *pwm;
+ struct pwm_args pargs;
const char *clk_name;
struct clk *clk;
int ret;
if (IS_ERR(pwm))
return PTR_ERR(pwm);
- if (!pwm->period) {
+ pwm_get_args(pwm, &pargs);
+ if (!pargs.period) {
dev_err(&pdev->dev, "invalid PWM period\n");
return -EINVAL;
}
if (of_property_read_u32(node, "clock-frequency", &clk_pwm->fixed_rate))
- clk_pwm->fixed_rate = NSEC_PER_SEC / pwm->period;
+ clk_pwm->fixed_rate = NSEC_PER_SEC / pargs.period;
- if (pwm->period != NSEC_PER_SEC / clk_pwm->fixed_rate &&
- pwm->period != DIV_ROUND_UP(NSEC_PER_SEC, clk_pwm->fixed_rate)) {
+ if (pargs.period != NSEC_PER_SEC / clk_pwm->fixed_rate &&
+ pargs.period != DIV_ROUND_UP(NSEC_PER_SEC, clk_pwm->fixed_rate)) {
dev_err(&pdev->dev,
"clock-frequency does not match PWM period\n");
return -EINVAL;
}
- ret = pwm_config(pwm, (pwm->period + 1) >> 1, pwm->period);
+ /*
+ * FIXME: pwm_apply_args() should be removed when switching to the
+ * atomic PWM API.
+ */
+ pwm_apply_args(pwm);
+ ret = pwm_config(pwm, (pargs.period + 1) >> 1, pargs.period);
if (ret < 0)
return ret;
return -ENODEV;
}
+ /*
+ * FIXME: pwm_apply_args() should be removed when switching to
+ * the atomic PWM API.
+ */
+ pwm_apply_args(panel->backlight.pwm);
+
retval = pwm_config(panel->backlight.pwm, CRC_PMIC_PWM_PERIOD_NS,
CRC_PMIC_PWM_PERIOD_NS);
if (retval < 0) {
static int __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
{
+ struct pwm_args pargs;
unsigned long duty;
int ret = 0;
+ pwm_get_args(ctx->pwm, &pargs);
+
mutex_lock(&ctx->lock);
if (ctx->pwm_value == pwm)
goto exit_set_pwm_err;
- duty = DIV_ROUND_UP(pwm * (ctx->pwm->period - 1), MAX_PWM);
- ret = pwm_config(ctx->pwm, duty, ctx->pwm->period);
+ duty = DIV_ROUND_UP(pwm * (pargs.period - 1), MAX_PWM);
+ ret = pwm_config(ctx->pwm, duty, pargs.period);
if (ret)
goto exit_set_pwm_err;
{
struct thermal_cooling_device *cdev;
struct pwm_fan_ctx *ctx;
+ struct pwm_args pargs;
struct device *hwmon;
int duty_cycle;
int ret;
platform_set_drvdata(pdev, ctx);
+ /*
+ * FIXME: pwm_apply_args() should be removed when switching to the
+ * atomic PWM API.
+ */
+ pwm_apply_args(ctx->pwm);
+
/* Set duty cycle to maximum allowed */
- duty_cycle = ctx->pwm->period - 1;
+ pwm_get_args(ctx->pwm, &pargs);
+
+ duty_cycle = pargs.period - 1;
ctx->pwm_value = MAX_PWM;
- ret = pwm_config(ctx->pwm, duty_cycle, ctx->pwm->period);
+ ret = pwm_config(ctx->pwm, duty_cycle, pargs.period);
if (ret) {
dev_err(&pdev->dev, "Failed to configure PWM\n");
return ret;
static int pwm_fan_resume(struct device *dev)
{
struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
+ struct pwm_args pargs;
unsigned long duty;
int ret;
if (ctx->pwm_value == 0)
return 0;
- duty = DIV_ROUND_UP(ctx->pwm_value * (ctx->pwm->period - 1), MAX_PWM);
- ret = pwm_config(ctx->pwm, duty, ctx->pwm->period);
+ pwm_get_args(ctx->pwm, &pargs);
+ duty = DIV_ROUND_UP(ctx->pwm_value * (pargs.period - 1), MAX_PWM);
+ ret = pwm_config(ctx->pwm, duty, pargs.period);
if (ret)
return ret;
return pwm_enable(ctx->pwm);
static int max77693_haptic_set_duty_cycle(struct max77693_haptic *haptic)
{
- int delta = (haptic->pwm_dev->period + haptic->pwm_duty) / 2;
+ struct pwm_args pargs;
+ int delta;
int error;
- error = pwm_config(haptic->pwm_dev, delta, haptic->pwm_dev->period);
+ pwm_get_args(haptic->pwm_dev, &pargs);
+ delta = (pargs.period + haptic->pwm_duty) / 2;
+ error = pwm_config(haptic->pwm_dev, delta, pargs.period);
if (error) {
dev_err(haptic->dev, "failed to configure pwm: %d\n", error);
return error;
struct ff_effect *effect)
{
struct max77693_haptic *haptic = input_get_drvdata(dev);
+ struct pwm_args pargs;
u64 period_mag_multi;
haptic->magnitude = effect->u.rumble.strong_magnitude;
* The formula to convert magnitude to pwm_duty as follows:
* - pwm_duty = (magnitude * pwm_period) / MAX_MAGNITUDE(0xFFFF)
*/
- period_mag_multi = (u64)haptic->pwm_dev->period * haptic->magnitude;
+ pwm_get_args(haptic->pwm_dev, &pargs);
+ period_mag_multi = (u64)pargs.period * haptic->magnitude;
haptic->pwm_duty = (unsigned int)(period_mag_multi >>
MAX_MAGNITUDE_SHIFT);
return PTR_ERR(haptic->pwm_dev);
}
+ /*
+ * FIXME: pwm_apply_args() should be removed when switching to the
+ * atomic PWM API.
+ */
+ pwm_apply_args(haptic->pwm_dev);
+
haptic->motor_reg = devm_regulator_get(&pdev->dev, "haptic");
if (IS_ERR(haptic->motor_reg)) {
dev_err(&pdev->dev, "failed to get regulator\n");
error);
goto err_free_mem;
}
+
+ /*
+ * FIXME: pwm_apply_args() should be removed when switching to
+ * the atomic PWM API.
+ */
+ pwm_apply_args(chip->pwm);
break;
default:
goto err_free;
}
+ /*
+ * FIXME: pwm_apply_args() should be removed when switching to
+ * the atomic PWM API.
+ */
+ pwm_apply_args(beeper->pwm);
+
beeper->input = input_allocate_device();
if (!beeper->input) {
dev_err(&pdev->dev, "Failed to allocate input device\n");
struct led_pwm *led, struct device_node *child)
{
struct led_pwm_data *led_data = &priv->leds[priv->num_leds];
+ struct pwm_args pargs;
int ret;
led_data->active_low = led->active_low;
else
led_data->cdev.brightness_set_blocking = led_pwm_set_blocking;
- led_data->period = pwm_get_period(led_data->pwm);
+ /*
+ * FIXME: pwm_apply_args() should be removed when switching to the
+ * atomic PWM API.
+ */
+ pwm_apply_args(led_data->pwm);
+
+ pwm_get_args(led_data->pwm, &pargs);
+
+ led_data->period = pargs.period;
if (!led_data->period && (led->pwm_period_ns > 0))
led_data->period = led->pwm_period_ns;
for (i = 0; i < chip->npwm; i++) {
struct pwm_device *pwm = &chip->pwms[i];
+
radix_tree_delete(&pwm_tree, pwm->pwm);
}
set_bit(PWMF_REQUESTED, &pwm->flags);
pwm->label = label;
- /*
- * FIXME: This should be removed once all PWM users properly make use
- * of struct pwm_args to initialize the PWM device. As long as this is
- * here, the PWM state and hardware state can get out of sync.
- */
- pwm_apply_args(pwm);
-
return 0;
}
}
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
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);
if (ret < 0)
goto out;
- chip->pwms = kzalloc(chip->npwm * sizeof(*pwm), GFP_KERNEL);
+ chip->pwms = kcalloc(chip->npwm, sizeof(*pwm), GFP_KERNEL);
if (!chip->pwms) {
ret = -ENOMEM;
goto out;
pwm->chip = chip;
pwm->pwm = chip->base + i;
pwm->hwpwm = i;
- pwm->polarity = polarity;
- mutex_init(&pwm->lock);
+ pwm->state.polarity = polarity;
+
+ if (chip->ops->get_state)
+ chip->ops->get_state(chip, pwm, &pwm->state);
radix_tree_insert(&pwm_tree, pwm->pwm, 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 (err)
- return err;
-
- pwm->duty_cycle = duty_ns;
- pwm->period = period_ns;
+ if (!memcmp(state, &pwm->state, sizeof(*state)))
+ return 0;
- return 0;
-}
-EXPORT_SYMBOL_GPL(pwm_config);
+ if (pwm->chip->ops->apply) {
+ err = pwm->chip->ops->apply(pwm->chip, pwm, state);
+ if (err)
+ return err;
-/**
- * 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.
- */
-int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity)
-{
- int err;
+ pwm->state = *state;
+ } else {
+ /*
+ * FIXME: restore the initial state in case of error.
+ */
+ if (state->polarity != pwm->state.polarity) {
+ if (!pwm->chip->ops->set_polarity)
+ return -ENOTSUPP;
+
+ /*
+ * Changing the polarity of a running PWM is
+ * only allowed when the PWM driver implements
+ * ->apply().
+ */
+ 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;
+ }
- if (!pwm || !pwm->chip->ops)
- return -EINVAL;
+ 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;
- if (!pwm->chip->ops->set_polarity)
- return -ENOSYS;
+ pwm->state.duty_cycle = state->duty_cycle;
+ pwm->state.period = state->period;
+ }
- mutex_lock(&pwm->lock);
+ 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);
+ }
- if (pwm_is_enabled(pwm)) {
- err = -EBUSY;
- goto unlock;
+ pwm->state.enabled = state->enabled;
+ }
}
- err = pwm->chip->ops->set_polarity(pwm->chip, pwm, polarity);
- if (err)
- goto unlock;
-
- pwm->polarity = polarity;
-
-unlock:
- mutex_unlock(&pwm->lock);
- return err;
+ return 0;
}
-EXPORT_SYMBOL_GPL(pwm_set_polarity);
+EXPORT_SYMBOL_GPL(pwm_apply_state);
/**
- * pwm_enable() - start a PWM output toggling
+ * pwm_adjust_config() - adjust the current PWM config to the PWM arguments
* @pwm: PWM device
*
- * Returns: 0 on success or a negative error code on failure.
+ * 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_enable(struct pwm_device *pwm)
+int pwm_adjust_config(struct pwm_device *pwm)
{
- int err = 0;
+ struct pwm_state state;
+ struct pwm_args pargs;
- if (!pwm)
- return -EINVAL;
+ pwm_get_args(pwm, &pargs);
+ pwm_get_state(pwm, &state);
- mutex_lock(&pwm->lock);
+ /*
+ * 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;
- if (!test_and_set_bit(PWMF_ENABLED, &pwm->flags)) {
- err = pwm->chip->ops->enable(pwm->chip, pwm);
- if (err)
- clear_bit(PWMF_ENABLED, &pwm->flags);
+ return pwm_apply_state(pwm, &state);
}
- mutex_unlock(&pwm->lock);
+ /*
+ * 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;
- return err;
-}
-EXPORT_SYMBOL_GPL(pwm_enable);
+ do_div(dutycycle, state.period);
+ state.duty_cycle = dutycycle;
+ state.period = pargs.period;
+ }
-/**
- * pwm_disable() - stop a PWM output toggling
- * @pwm: PWM device
- */
-void pwm_disable(struct pwm_device *pwm)
-{
- if (pwm && test_and_clear_bit(PWMF_ENABLED, &pwm->flags))
- pwm->chip->ops->disable(pwm->chip, pwm);
+ /*
+ * 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_disable);
+EXPORT_SYMBOL_GPL(pwm_adjust_config);
static struct pwm_chip *of_node_to_pwmchip(struct device_node *np)
{
if (!chip)
goto out;
- pwm->args.period = chosen->period;
- pwm->args.polarity = chosen->polarity;
-
pwm = pwm_request_from_chip(chip, chosen->index, con_id ?: dev_id);
if (IS_ERR(pwm))
goto out;
+ pwm->args.period = chosen->period;
+ pwm->args.polarity = chosen->polarity;
+
out:
mutex_unlock(&pwm_lookup_lock);
return pwm;
for (i = 0; i < chip->npwm; i++) {
struct pwm_device *pwm = &chip->pwms[i];
+ struct pwm_state state;
+
+ pwm_get_state(pwm, &state);
seq_printf(s, " pwm-%-3d (%-20.20s):", i, pwm->label);
if (test_bit(PWMF_REQUESTED, &pwm->flags))
seq_puts(s, " requested");
- if (pwm_is_enabled(pwm))
+ if (state.enabled)
seq_puts(s, " enabled");
+ seq_printf(s, " period: %u ns", state.period);
+ seq_printf(s, " duty: %u ns", state.duty_cycle);
+ seq_printf(s, " polarity: %s",
+ state.polarity ? "inverse" : "normal");
+
seq_puts(s, "\n");
}
}
return -EINVAL;
}
- if (pwm->period != period_ns) {
+ if (pwm_get_period(pwm) != period_ns) {
int clk_div;
/* changing the clk divisor, need to disable fisrt */
LPC18XX_PWM_EVSTATEMSK(lpc18xx_data->duty_event),
LPC18XX_PWM_EVSTATEMSK_ALL);
- if (pwm->polarity == PWM_POLARITY_NORMAL) {
+ if (pwm_get_polarity(pwm) == PWM_POLARITY_NORMAL) {
set_event = lpc18xx_pwm->period_event;
clear_event = lpc18xx_data->duty_event;
res_action = LPC18XX_PWM_RES_SET;
load_value, load_value, match_value, match_value);
omap->pdata->set_pwm(omap->dm_timer,
- pwm->polarity == PWM_POLARITY_INVERSED,
+ pwm_get_polarity(pwm) == PWM_POLARITY_INVERSED,
true,
PWM_OMAP_DMTIMER_TRIGGER_OVERFLOW_AND_COMPARE);
return div;
/* Let the core driver set pwm->period if disabled and duty_ns == 0 */
- if (!test_bit(PWMF_ENABLED, &pwm->flags) && !duty_ns)
+ if (!pwm_is_enabled(pwm) && !duty_ns)
return 0;
rcar_pwm_update(rp, RCAR_PWMCR_SYNC, RCAR_PWMCR_SYNC, RCAR_PWMCR);
val = sun4i_pwm_readl(pwm, PWM_CTRL_REG);
for (i = 0; i < pwm->chip.npwm; i++)
if (!(val & BIT_CH(PWM_ACT_STATE, i)))
- pwm->chip.pwms[i].polarity = PWM_POLARITY_INVERSED;
+ pwm_set_polarity(&pwm->chip.pwms[i],
+ PWM_POLARITY_INVERSED);
clk_disable_unprepare(pwm->clk);
return 0;
struct pwm_export {
struct device child;
struct pwm_device *pwm;
+ struct mutex lock;
};
static struct pwm_export *child_to_pwm_export(struct device *child)
char *buf)
{
const struct pwm_device *pwm = child_to_pwm_device(child);
+ struct pwm_state state;
- return sprintf(buf, "%u\n", pwm_get_period(pwm));
+ pwm_get_state(pwm, &state);
+
+ return sprintf(buf, "%u\n", state.period);
}
static ssize_t period_store(struct device *child,
struct device_attribute *attr,
const char *buf, size_t size)
{
- struct pwm_device *pwm = child_to_pwm_device(child);
+ struct pwm_export *export = child_to_pwm_export(child);
+ struct pwm_device *pwm = export->pwm;
+ struct pwm_state state;
unsigned int val;
int ret;
if (ret)
return ret;
- ret = pwm_config(pwm, pwm_get_duty_cycle(pwm), val);
+ mutex_lock(&export->lock);
+ pwm_get_state(pwm, &state);
+ state.period = val;
+ ret = pwm_apply_state(pwm, &state);
+ mutex_unlock(&export->lock);
return ret ? : size;
}
char *buf)
{
const struct pwm_device *pwm = child_to_pwm_device(child);
+ struct pwm_state state;
+
+ pwm_get_state(pwm, &state);
- return sprintf(buf, "%u\n", pwm_get_duty_cycle(pwm));
+ return sprintf(buf, "%u\n", state.duty_cycle);
}
static ssize_t duty_cycle_store(struct device *child,
struct device_attribute *attr,
const char *buf, size_t size)
{
- struct pwm_device *pwm = child_to_pwm_device(child);
+ struct pwm_export *export = child_to_pwm_export(child);
+ struct pwm_device *pwm = export->pwm;
+ struct pwm_state state;
unsigned int val;
int ret;
if (ret)
return ret;
- ret = pwm_config(pwm, val, pwm_get_period(pwm));
+ mutex_lock(&export->lock);
+ pwm_get_state(pwm, &state);
+ state.duty_cycle = val;
+ ret = pwm_apply_state(pwm, &state);
+ mutex_unlock(&export->lock);
return ret ? : size;
}
char *buf)
{
const struct pwm_device *pwm = child_to_pwm_device(child);
+ struct pwm_state state;
+
+ pwm_get_state(pwm, &state);
- return sprintf(buf, "%d\n", pwm_is_enabled(pwm));
+ return sprintf(buf, "%d\n", state.enabled);
}
static ssize_t enable_store(struct device *child,
struct device_attribute *attr,
const char *buf, size_t size)
{
- struct pwm_device *pwm = child_to_pwm_device(child);
+ struct pwm_export *export = child_to_pwm_export(child);
+ struct pwm_device *pwm = export->pwm;
+ struct pwm_state state;
int val, ret;
ret = kstrtoint(buf, 0, &val);
if (ret)
return ret;
+ mutex_lock(&export->lock);
+
+ pwm_get_state(pwm, &state);
+
switch (val) {
case 0:
- pwm_disable(pwm);
+ state.enabled = false;
break;
case 1:
- ret = pwm_enable(pwm);
+ state.enabled = true;
break;
default:
ret = -EINVAL;
- break;
+ goto unlock;
}
+ pwm_apply_state(pwm, &state);
+
+unlock:
+ mutex_unlock(&export->lock);
return ret ? : size;
}
{
const struct pwm_device *pwm = child_to_pwm_device(child);
const char *polarity = "unknown";
+ struct pwm_state state;
+
+ pwm_get_state(pwm, &state);
- switch (pwm_get_polarity(pwm)) {
+ switch (state.polarity) {
case PWM_POLARITY_NORMAL:
polarity = "normal";
break;
struct device_attribute *attr,
const char *buf, size_t size)
{
- struct pwm_device *pwm = child_to_pwm_device(child);
+ struct pwm_export *export = child_to_pwm_export(child);
+ struct pwm_device *pwm = export->pwm;
enum pwm_polarity polarity;
+ struct pwm_state state;
int ret;
if (sysfs_streq(buf, "normal"))
else
return -EINVAL;
- ret = pwm_set_polarity(pwm, polarity);
+ mutex_lock(&export->lock);
+ pwm_get_state(pwm, &state);
+ state.polarity = polarity;
+ ret = pwm_apply_state(pwm, &state);
+ mutex_unlock(&export->lock);
return ret ? : size;
}
}
export->pwm = pwm;
+ mutex_init(&export->lock);
export->child.release = pwm_export_release;
export->child.parent = parent;
static void lm3630a_pwm_ctrl(struct lm3630a_chip *pchip, int br, int br_max)
{
- unsigned int period = pwm_get_period(pchip->pwmd);
+ unsigned int period = pchip->pdata->pwm_period;
unsigned int duty = br * period / br_max;
pwm_config(pchip->pwmd, duty, period);
dev_err(&client->dev, "fail : get pwm device\n");
return PTR_ERR(pchip->pwmd);
}
+
+ /*
+ * FIXME: pwm_apply_args() should be removed when switching to
+ * the atomic PWM API.
+ */
+ pwm_apply_args(pchip->pwmd);
}
- pchip->pwmd->period = pdata->pwm_period;
/* interrupt enable : irq 0 is not allowed */
pchip->irq = client->irq;
return;
lp->pwm = pwm;
+
+ /*
+ * FIXME: pwm_apply_args() should be removed when switching to
+ * the atomic PWM API.
+ */
+ pwm_apply_args(pwm);
}
pwm_config(lp->pwm, duty, period);
}
bl->pwm = pwm;
+
+ /*
+ * FIXME: pwm_apply_args() should be removed when switching to
+ * the atomic PWM API.
+ */
+ pwm_apply_args(pwm);
}
pwm_config(bl->pwm, duty, period);
struct device_node *node = pdev->dev.of_node;
struct pwm_bl_data *pb;
int initial_blank = FB_BLANK_UNBLANK;
+ struct pwm_args pargs;
int ret;
if (!data) {
dev_dbg(&pdev->dev, "got pwm for backlight\n");
+ /*
+ * FIXME: pwm_apply_args() should be removed when switching to
+ * the atomic PWM API.
+ */
+ pwm_apply_args(pb->pwm);
+
/*
* The DT case will set the pwm_period_ns field to 0 and store the
* period, parsed from the DT, in the PWM device. For the non-DT case,
* set the period from platform data if it has not already been set
* via the PWM lookup table.
*/
- pb->period = pwm_get_period(pb->pwm);
- if (!pb->period && (data->pwm_period_ns > 0)) {
+ pwm_get_args(pb->pwm, &pargs);
+ pb->period = pargs.period;
+ if (!pb->period && (data->pwm_period_ns > 0))
pb->period = data->pwm_period_ns;
- pwm_set_period(pb->pwm, data->pwm_period_ns);
- }
pb->lth_brightness = data->lth_brightness * (pb->period / pb->scale);
{
int ret;
u32 precharge, dclk, com_invdir, compins;
+ struct pwm_args pargs;
if (par->device_info->need_pwm) {
par->pwm = pwm_get(&par->client->dev, NULL);
return PTR_ERR(par->pwm);
}
- par->pwm_period = pwm_get_period(par->pwm);
+ /*
+ * FIXME: pwm_apply_args() should be removed when switching to
+ * the atomic PWM API.
+ */
+ pwm_apply_args(par->pwm);
+
+ pwm_get_args(par->pwm, &pargs);
+
+ par->pwm_period = pargs.period;
/* Enable the PWM */
pwm_config(par->pwm, par->pwm_period / 2, par->pwm_period);
pwm_enable(par->pwm);
#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;
projects / linux-2.6-block.git / commitdiff