Commit ace41d75 authored by Uwe Kleine-König's avatar Uwe Kleine-König Committed by Thierry Reding
Browse files

pwm: sifive: Ensure the clk is enabled exactly once per running PWM 



.apply() assumes the clk to be for a given PWM iff the PWM is enabled.
So make sure this is the case when .probe() completes. And in .remove()
disable the according number of times.

This fixes a clk enable/disable imbalance, if some PWMs are already running
at probe time.

Fixes: 9e37a53e (pwm: sifive: Add a driver for SiFive SoC PWM)
Signed-off-by: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Tested-by: default avatarEmil Renner Berthing <emil.renner.berthing@canonical.com>
Signed-off-by: default avatarThierry Reding <thierry.reding@gmail.com>
parent 1695b421

drivers/pwm/pwm-sifive.c

+37 −9
Original line number Diff line number Diff line
@@ -216,6 +216,8 @@ static int pwm_sifive_probe(struct platform_device *pdev) 
	struct pwm_sifive_ddata *ddata;

	struct pwm_chip *chip;

	int ret;

	u32 val;

	unsigned int enabled_pwms = 0, enabled_clks = 1;



	ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);

	if (!ddata)
@@ -242,6 +244,33 @@ static int pwm_sifive_probe(struct platform_device *pdev) 
		return ret;

	}



	val = readl(ddata->regs + PWM_SIFIVE_PWMCFG);

	if (val & PWM_SIFIVE_PWMCFG_EN_ALWAYS) {

		unsigned int i;



		for (i = 0; i < chip->npwm; ++i) {

			val = readl(ddata->regs + PWM_SIFIVE_PWMCMP(i));

			if (val > 0)

				++enabled_pwms;

		}

	}



	/* The clk should be on once for each running PWM. */

	if (enabled_pwms) {

		while (enabled_clks < enabled_pwms) {

			/* This is not expected to fail as the clk is already on */

			ret = clk_enable(ddata->clk);

			if (unlikely(ret)) {

				dev_err_probe(dev, ret, "Failed to enable clk\n");

				goto disable_clk;

			}

			++enabled_clks;

		}

	} else {

		clk_disable(ddata->clk);

		enabled_clks = 0;

	}



	/* Watch for changes to underlying clock frequency */

	ddata->notifier.notifier_call = pwm_sifive_clock_notifier;

	ret = clk_notifier_register(ddata->clk, &ddata->notifier);
@@ -264,7 +293,11 @@ static int pwm_sifive_probe(struct platform_device *pdev) 
unregister_clk:

	clk_notifier_unregister(ddata->clk, &ddata->notifier);

disable_clk:

	clk_disable_unprepare(ddata->clk);

	while (enabled_clks) {

		clk_disable(ddata->clk);

		--enabled_clks;

	}

	clk_unprepare(ddata->clk);



	return ret;

}
@@ -272,21 +305,16 @@ static int pwm_sifive_probe(struct platform_device *pdev) 
static int pwm_sifive_remove(struct platform_device *dev)

{

	struct pwm_sifive_ddata *ddata = platform_get_drvdata(dev);

	bool is_enabled = false;

	struct pwm_device *pwm;

	int ch;



	for (ch = 0; ch < ddata->chip.npwm; ch++) {

		pwm = &ddata->chip.pwms[ch];

		if (pwm->state.enabled) {

			is_enabled = true;

			break;

		}

	}

	if (is_enabled)

		if (pwm->state.enabled)

			clk_disable(ddata->clk);

	}



	clk_disable_unprepare(ddata->clk);

	clk_unprepare(ddata->clk);

	pwmchip_remove(&ddata->chip);

	clk_notifier_unregister(ddata->clk, &ddata->notifier);