Commit b5a497a7 authored by Fabrice Gasnier's avatar Fabrice Gasnier Committed by Daniel Lezcano
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clocksource/drivers/stm32-lptimer: Add support for suspend / resume 



Add support for power management on STM32 LPTIMER clocksource driver:
- Upon clockevents_suspend(), shutdown the LPTIMER, and balance the
clk_prepare_enable() from the probe routine.
- Upon clockevents_resume(), restore the prescaler that may have been lost
during low power mode, and restore the clock.

Signed-off-by: default avatarFabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20250224172101.3448398-1-fabrice.gasnier@foss.st.com


Signed-off-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
parent f7803f79

drivers/clocksource/timer-stm32-lp.c

+29 −3
Original line number Diff line number Diff line
@@ -24,7 +24,9 @@ struct stm32_lp_private { 
	struct regmap *reg;

	struct clock_event_device clkevt;

	unsigned long period;

	u32 psc;

	struct device *dev;

	struct clk *clk;

};



static struct stm32_lp_private*
@@ -120,6 +122,27 @@ static void stm32_clkevent_lp_set_prescaler(struct stm32_lp_private *priv, 
	/* Adjust rate and period given the prescaler value */

	*rate = DIV_ROUND_CLOSEST(*rate, (1 << i));

	priv->period = DIV_ROUND_UP(*rate, HZ);

	priv->psc = i;

}



static void stm32_clkevent_lp_suspend(struct clock_event_device *clkevt)

{

	struct stm32_lp_private *priv = to_priv(clkevt);



	stm32_clkevent_lp_shutdown(clkevt);



	/* balance clk_prepare_enable() from the probe */

	clk_disable_unprepare(priv->clk);

}



static void stm32_clkevent_lp_resume(struct clock_event_device *clkevt)

{

	struct stm32_lp_private *priv = to_priv(clkevt);



	clk_prepare_enable(priv->clk);



	/* restore prescaler */

	regmap_write(priv->reg, STM32_LPTIM_CFGR, priv->psc << CFGR_PSC_OFFSET);

}



static void stm32_clkevent_lp_init(struct stm32_lp_private *priv,
@@ -134,6 +157,8 @@ static void stm32_clkevent_lp_init(struct stm32_lp_private *priv, 
	priv->clkevt.set_state_oneshot = stm32_clkevent_lp_set_oneshot;

	priv->clkevt.set_next_event = stm32_clkevent_lp_set_next_event;

	priv->clkevt.rating = STM32_LP_RATING;

	priv->clkevt.suspend = stm32_clkevent_lp_suspend;

	priv->clkevt.resume = stm32_clkevent_lp_resume;



	clockevents_config_and_register(&priv->clkevt, rate, 0x1,

					STM32_LPTIM_MAX_ARR);
@@ -151,11 +176,12 @@ static int stm32_clkevent_lp_probe(struct platform_device *pdev) 
		return -ENOMEM;



	priv->reg = ddata->regmap;

	ret = clk_prepare_enable(ddata->clk);

	priv->clk = ddata->clk;

	ret = clk_prepare_enable(priv->clk);

	if (ret)

		return -EINVAL;



	rate = clk_get_rate(ddata->clk);

	rate = clk_get_rate(priv->clk);

	if (!rate) {

		ret = -EINVAL;

		goto out_clk_disable;
@@ -191,7 +217,7 @@ static int stm32_clkevent_lp_probe(struct platform_device *pdev) 
	return 0;



out_clk_disable:

	clk_disable_unprepare(ddata->clk);

	clk_disable_unprepare(priv->clk);

	return ret;

}