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

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.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: 9e37a53eb0 (pwm: sifive: Add a driver for SiFive SoC PWM)
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Tested-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This commit is contained in:
Uwe Kleine-König 2022-07-21 12:31:28 +02:00 • committed by Thierry Reding
parent 1695b421e1
commit ace41d7564
1 changed files with 37 additions and 9 deletions
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46
drivers/pwm/pwm-sifive.c
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@ -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 @@ disable_clk:
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 (pwm->state.enabled)
clk_disable(ddata->clk);
}
if (is_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);