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Commit 18c58878 authored by Thierry Reding's avatar Thierry Reding
Browse files

Merge branch 'for-4.7/pwm-atomic' into for-next

parents d2a3f206 23e3523f

Documentation/pwm.txt

+28 −2
Original line number Diff line number Diff line
@@ -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

-------

arch/arm/mach-s3c24xx/mach-rx1950.c

+6 −0
Original line number Diff line number Diff line
@@ -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);

drivers/clk/clk-pwm.c

+12 −5
Original line number Diff line number Diff line
@@ -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;

drivers/gpu/drm/i915/intel_panel.c

+6 −0
Original line number Diff line number Diff line
@@ -1640,6 +1640,12 @@ 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) {

drivers/hwmon/pwm-fan.c

+20 −6
Original line number Diff line number Diff line
@@ -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);