diff options
| -rw-r--r-- | Documentation/pwm.txt | 30 | ||||
| -rw-r--r-- | arch/arm/mach-s3c24xx/mach-rx1950.c | 6 | ||||
| -rw-r--r-- | drivers/clk/clk-pwm.c | 17 | ||||
| -rw-r--r-- | drivers/gpu/drm/i915/intel_panel.c | 6 | ||||
| -rw-r--r-- | drivers/hwmon/pwm-fan.c | 26 | ||||
| -rw-r--r-- | drivers/input/misc/max77693-haptic.c | 17 | ||||
| -rw-r--r-- | drivers/input/misc/max8997_haptic.c | 6 | ||||
| -rw-r--r-- | drivers/input/misc/pwm-beeper.c | 6 | ||||
| -rw-r--r-- | drivers/leds/leds-pwm.c | 11 | ||||
| -rw-r--r-- | drivers/pwm/core.c | 224 | ||||
| -rw-r--r-- | drivers/pwm/pwm-crc.c | 2 | ||||
| -rw-r--r-- | drivers/pwm/pwm-lpc18xx-sct.c | 2 | ||||
| -rw-r--r-- | drivers/pwm/pwm-omap-dmtimer.c | 2 | ||||
| -rw-r--r-- | drivers/pwm/pwm-rcar.c | 2 | ||||
| -rw-r--r-- | drivers/pwm/pwm-sun4i.c | 3 | ||||
| -rw-r--r-- | drivers/pwm/sysfs.c | 70 | ||||
| -rw-r--r-- | drivers/video/backlight/lm3630a_bl.c | 9 | ||||
| -rw-r--r-- | drivers/video/backlight/lp855x_bl.c | 6 | ||||
| -rw-r--r-- | drivers/video/backlight/lp8788_bl.c | 6 | ||||
| -rw-r--r-- | drivers/video/backlight/pwm_bl.c | 14 | ||||
| -rw-r--r-- | drivers/video/fbdev/ssd1307fb.c | 11 | ||||
| -rw-r--r-- | include/linux/pwm.h | 319 |
22 files changed, 585 insertions, 210 deletions
diff --git a/Documentation/pwm.txt b/Documentation/pwm.txt index ca895fd211e4..789b27c6ec99 100644 --- a/Documentation/pwm.txt +++ b/Documentation/pwm.txt @@ -42,9 +42,26 @@ variants of these functions, devm_pwm_get() and devm_pwm_put(), also exist. 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 ----------------------------------- @@ -105,6 +122,15 @@ goes low for the remainder of the period. Conversely, a signal with inversed 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 ------- diff --git a/arch/arm/mach-s3c24xx/mach-rx1950.c b/arch/arm/mach-s3c24xx/mach-rx1950.c index 774c982a7b7e..25a139bb9826 100644 --- a/arch/arm/mach-s3c24xx/mach-rx1950.c +++ b/arch/arm/mach-s3c24xx/mach-rx1950.c @@ -496,6 +496,12 @@ static int rx1950_backlight_init(struct device *dev) 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); diff --git a/drivers/clk/clk-pwm.c b/drivers/clk/clk-pwm.c index 883045814dac..1630a1f085f7 100644 --- a/drivers/clk/clk-pwm.c +++ b/drivers/clk/clk-pwm.c @@ -59,6 +59,7 @@ static int clk_pwm_probe(struct platform_device *pdev) 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; @@ -71,22 +72,28 @@ static int clk_pwm_probe(struct platform_device *pdev) 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; diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c index a0788763757b..8357d571553a 100644 --- a/drivers/gpu/drm/i915/intel_panel.c +++ b/drivers/gpu/drm/i915/intel_panel.c @@ -1638,6 +1638,12 @@ static int pwm_setup_backlight(struct intel_connector *connector, 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) { diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c index 3e23003f78b0..f9af3935b427 100644 --- a/drivers/hwmon/pwm-fan.c +++ b/drivers/hwmon/pwm-fan.c @@ -40,15 +40,18 @@ struct pwm_fan_ctx { 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; @@ -215,6 +218,7 @@ static int pwm_fan_probe(struct platform_device *pdev) { struct thermal_cooling_device *cdev; struct pwm_fan_ctx *ctx; + struct pwm_args pargs; struct device *hwmon; int duty_cycle; int ret; @@ -233,11 +237,19 @@ static int pwm_fan_probe(struct platform_device *pdev) 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; @@ -303,14 +315,16 @@ static int pwm_fan_suspend(struct device *dev) 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); diff --git a/drivers/input/misc/max77693-haptic.c b/drivers/input/misc/max77693-haptic.c index 6d96bff32a0e..29ddeb7be84b 100644 --- a/drivers/input/misc/max77693-haptic.c +++ b/drivers/input/misc/max77693-haptic.c @@ -70,10 +70,13 @@ struct max77693_haptic { 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; @@ -234,6 +237,7 @@ static int max77693_haptic_play_effect(struct input_dev *dev, void *data, 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; @@ -245,7 +249,8 @@ static int max77693_haptic_play_effect(struct input_dev *dev, void *data, * 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); @@ -329,6 +334,12 @@ static int max77693_haptic_probe(struct platform_device *pdev) 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"); diff --git a/drivers/input/misc/max8997_haptic.c b/drivers/input/misc/max8997_haptic.c index 8d6326d7e7be..99bc762881d5 100644 --- a/drivers/input/misc/max8997_haptic.c +++ b/drivers/input/misc/max8997_haptic.c @@ -306,6 +306,12 @@ static int max8997_haptic_probe(struct platform_device *pdev) 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: diff --git a/drivers/input/misc/pwm-beeper.c b/drivers/input/misc/pwm-beeper.c index f2261ab54701..8d7133268745 100644 --- a/drivers/input/misc/pwm-beeper.c +++ b/drivers/input/misc/pwm-beeper.c @@ -87,6 +87,12 @@ static int pwm_beeper_probe(struct platform_device *pdev) 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"); diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c index 4783bacb2e9d..a9145aa7f36a 100644 --- a/drivers/leds/leds-pwm.c +++ b/drivers/leds/leds-pwm.c @@ -91,6 +91,7 @@ static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv, 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; @@ -117,7 +118,15 @@ static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv, 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; diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index 680fbc795a0a..dba3843c53b8 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -75,6 +75,7 @@ static void free_pwms(struct pwm_chip *chip) for (i = 0; i < chip->npwm; i++) { struct pwm_device *pwm = &chip->pwms[i]; + radix_tree_delete(&pwm_tree, pwm->pwm); } @@ -128,13 +129,6 @@ static int pwm_device_request(struct pwm_device *pwm, const char *label) 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; } @@ -233,6 +227,19 @@ 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 @@ -251,8 +258,10 @@ 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); @@ -261,7 +270,7 @@ int pwmchip_add_with_polarity(struct pwm_chip *chip, 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; @@ -275,8 +284,10 @@ int pwmchip_add_with_polarity(struct pwm_chip *chip, 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); } @@ -436,107 +447,138 @@ 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 (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) { @@ -754,13 +796,13 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id) 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; @@ -907,15 +949,23 @@ static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s) 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"); } } diff --git a/drivers/pwm/pwm-crc.c b/drivers/pwm/pwm-crc.c index 7101c7020bf4..bd0ebd04856a 100644 --- a/drivers/pwm/pwm-crc.c +++ b/drivers/pwm/pwm-crc.c @@ -75,7 +75,7 @@ static int crc_pwm_config(struct pwm_chip *c, struct pwm_device *pwm, 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 */ diff --git a/drivers/pwm/pwm-lpc18xx-sct.c b/drivers/pwm/pwm-lpc18xx-sct.c index 9861fed4e67d..19dc64cab2f0 100644 --- a/drivers/pwm/pwm-lpc18xx-sct.c +++ b/drivers/pwm/pwm-lpc18xx-sct.c @@ -249,7 +249,7 @@ static int lpc18xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) 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; diff --git a/drivers/pwm/pwm-omap-dmtimer.c b/drivers/pwm/pwm-omap-dmtimer.c index b7e6ecba7d5c..3e95090cd7cf 100644 --- a/drivers/pwm/pwm-omap-dmtimer.c +++ b/drivers/pwm/pwm-omap-dmtimer.c @@ -192,7 +192,7 @@ static int pwm_omap_dmtimer_config(struct pwm_chip *chip, 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); diff --git a/drivers/pwm/pwm-rcar.c b/drivers/pwm/pwm-rcar.c index 7b8ac0678137..1c85ecc9e7ac 100644 --- a/drivers/pwm/pwm-rcar.c +++ b/drivers/pwm/pwm-rcar.c @@ -157,7 +157,7 @@ static int rcar_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, 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); diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c index 67af9f62361f..03a99a53c39e 100644 --- a/drivers/pwm/pwm-sun4i.c +++ b/drivers/pwm/pwm-sun4i.c @@ -354,7 +354,8 @@ static int sun4i_pwm_probe(struct platform_device *pdev) 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; diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c index 9c90886f4123..d98599249a05 100644 --- a/drivers/pwm/sysfs.c +++ b/drivers/pwm/sysfs.c @@ -26,6 +26,7 @@ struct pwm_export { struct device child; struct pwm_device *pwm; + struct mutex lock; }; static struct pwm_export *child_to_pwm_export(struct device *child) @@ -45,15 +46,20 @@ static ssize_t period_show(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; @@ -61,7 +67,11 @@ static ssize_t period_store(struct device *child, 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; } @@ -71,15 +81,20 @@ static ssize_t duty_cycle_show(struct device *child, 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; @@ -87,7 +102,11 @@ static ssize_t duty_cycle_store(struct device *child, 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; } @@ -97,33 +116,46 @@ static ssize_t enable_show(struct device *child, 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; } @@ -133,8 +165,11 @@ static ssize_t polarity_show(struct device *child, { 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; @@ -151,8 +186,10 @@ static ssize_t polarity_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; enum pwm_polarity polarity; + struct pwm_state state; int ret; if (sysfs_streq(buf, "normal")) @@ -162,7 +199,11 @@ static ssize_t polarity_store(struct device *child, 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; } @@ -203,6 +244,7 @@ static int pwm_export_child(struct device *parent, struct pwm_device *pwm) } export->pwm = pwm; + mutex_init(&export->lock); export->child.release = pwm_export_release; export->child.parent = parent; diff --git a/drivers/video/backlight/lm3630a_bl.c b/drivers/video/backlight/lm3630a_bl.c index 35fe4825a454..60d6c2ac87aa 100644 --- a/drivers/video/backlight/lm3630a_bl.c +++ b/drivers/video/backlight/lm3630a_bl.c @@ -162,7 +162,7 @@ static int lm3630a_intr_config(struct lm3630a_chip *pchip) 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); @@ -424,8 +424,13 @@ static int lm3630a_probe(struct i2c_client *client, 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; diff --git a/drivers/video/backlight/lp855x_bl.c b/drivers/video/backlight/lp855x_bl.c index daca9e6a2bb3..e5b14f52628f 100644 --- a/drivers/video/backlight/lp855x_bl.c +++ b/drivers/video/backlight/lp855x_bl.c @@ -246,6 +246,12 @@ static void lp855x_pwm_ctrl(struct lp855x *lp, int br, int max_br) 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); diff --git a/drivers/video/backlight/lp8788_bl.c b/drivers/video/backlight/lp8788_bl.c index 5d583d7a517b..cf869ec90cce 100644 --- a/drivers/video/backlight/lp8788_bl.c +++ b/drivers/video/backlight/lp8788_bl.c @@ -145,6 +145,12 @@ static void lp8788_pwm_ctrl(struct lp8788_bl *bl, int br, int max_br) } 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); diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c index 64f9e1b8655f..b2b366bb0f97 100644 --- a/drivers/video/backlight/pwm_bl.c +++ b/drivers/video/backlight/pwm_bl.c @@ -201,6 +201,7 @@ static int pwm_backlight_probe(struct platform_device *pdev) 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) { @@ -307,16 +308,21 @@ static int pwm_backlight_probe(struct platform_device *pdev) 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); diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c index 21dafe53ca49..a9c45c89b15e 100644 --- a/drivers/video/fbdev/ssd1307fb.c +++ b/drivers/video/fbdev/ssd1307fb.c @@ -286,6 +286,7 @@ static int ssd1307fb_init(struct ssd1307fb_par *par) { 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); @@ -294,7 +295,15 @@ static int ssd1307fb_init(struct ssd1307fb_par *par) 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); diff --git a/include/linux/pwm.h b/include/linux/pwm.h index b78d27c42629..17018f3c066e 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -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; /** @@ -94,8 +42,21 @@ struct pwm_args { 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; }; /** @@ -106,11 +67,8 @@ enum { * @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; @@ -119,50 +77,68 @@ struct pwm_device { 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, @@ -171,12 +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_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 @@ -185,6 +155,13 @@ 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. * @dbg_show: optional routine to show contents in debugfs * @owner: helps prevent removal of modules exporting active PWMs */ @@ -197,6 +174,10 @@ 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 void (*dbg_show)(struct pwm_chip *chip, struct seq_file *s); #endif @@ -232,6 +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); @@ -257,6 +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; @@ -328,6 +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; |