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Message-Id: <20230608-pwm-stm32-get-state-v1-1-db7e58a7461b@pengutronix.de>
Date: Thu, 08 Jun 2023 16:06:02 +0200
From: Philipp Zabel <p.zabel@...gutronix.de>
To: Fabrice Gasnier <fabrice.gasnier@...s.st.com>,
Thierry Reding <thierry.reding@...il.com>,
Uwe Kleine-König
<u.kleine-koenig@...gutronix.de>,
Maxime Coquelin <mcoquelin.stm32@...il.com>,
Alexandre Torgue <alexandre.torgue@...s.st.com>
Cc: linux-pwm@...r.kernel.org,
linux-stm32@...md-mailman.stormreply.com,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Philipp Zabel <p.zabel@...gutronix.de>
Subject: [PATCH] pwm: stm32: Implement .get_state()
Stop stm32_pwm_detect_channels() from disabling all channels and count
the number of enabled PWMs to keep the clock running. Implement the
&pwm_ops->get_state callback so drivers can inherit PWM state set by
the bootloader.
Signed-off-by: Philipp Zabel <p.zabel@...gutronix.de>
---
Make the necessary changes to allow inheriting PWM state set by the
bootloader, for example to avoid flickering with a pre-enabled PWM
backlight.
---
drivers/pwm/pwm-stm32.c | 75 ++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 59 insertions(+), 16 deletions(-)
diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c
index 62e397aeb9aa..e0677c954bdf 100644
--- a/drivers/pwm/pwm-stm32.c
+++ b/drivers/pwm/pwm-stm32.c
@@ -52,6 +52,21 @@ static u32 active_channels(struct stm32_pwm *dev)
return ccer & TIM_CCER_CCXE;
}
+static int read_ccrx(struct stm32_pwm *dev, int ch, u32 *value)
+{
+ switch (ch) {
+ case 0:
+ return regmap_read(dev->regmap, TIM_CCR1, value);
+ case 1:
+ return regmap_read(dev->regmap, TIM_CCR2, value);
+ case 2:
+ return regmap_read(dev->regmap, TIM_CCR3, value);
+ case 3:
+ return regmap_read(dev->regmap, TIM_CCR4, value);
+ }
+ return -EINVAL;
+}
+
static int write_ccrx(struct stm32_pwm *dev, int ch, u32 value)
{
switch (ch) {
@@ -486,9 +501,40 @@ static int stm32_pwm_apply_locked(struct pwm_chip *chip, struct pwm_device *pwm,
return ret;
}
+static int stm32_pwm_get_state(struct pwm_chip *chip,
+ struct pwm_device *pwm, struct pwm_state *state)
+{
+ struct stm32_pwm *priv = to_stm32_pwm_dev(chip);
+ int ch = pwm->hwpwm;
+ unsigned long rate;
+ u32 ccer, psc, arr, ccr;
+ u64 dty, prd;
+ int ret;
+
+ ret = regmap_read(priv->regmap, TIM_CCER, &ccer);
+ if (ret)
+ return ret;
+
+ state->enabled = ccer & (TIM_CCER_CC1E << (ch * 4));
+ state->polarity = (ccer & (TIM_CCER_CC1P << (ch * 4))) ?
+ PWM_POLARITY_INVERSED : PWM_POLARITY_NORMAL;
+ regmap_read(priv->regmap, TIM_PSC, &psc);
+ regmap_read(priv->regmap, TIM_ARR, &arr);
+ read_ccrx(priv, ch, &ccr);
+ rate = clk_get_rate(priv->clk);
+
+ prd = (u64)NSEC_PER_SEC * (psc + 1) * (arr + 1);
+ state->period = DIV_ROUND_UP_ULL(prd, rate);
+ dty = (u64)NSEC_PER_SEC * (psc + 1) * ccr;
+ state->duty_cycle = DIV_ROUND_UP_ULL(dty, rate);
+
+ return ret;
+}
+
static const struct pwm_ops stm32pwm_ops = {
.owner = THIS_MODULE,
.apply = stm32_pwm_apply_locked,
+ .get_state = stm32_pwm_get_state,
.capture = IS_ENABLED(CONFIG_DMA_ENGINE) ? stm32_pwm_capture : NULL,
};
@@ -579,30 +625,22 @@ static void stm32_pwm_detect_complementary(struct stm32_pwm *priv)
priv->have_complementary_output = (ccer != 0);
}
-static int stm32_pwm_detect_channels(struct stm32_pwm *priv)
+static int stm32_pwm_detect_channels(struct stm32_pwm *priv, int *n_enabled)
{
- u32 ccer;
- int npwm = 0;
+ u32 ccer, ccer_backup;
+ int npwm;
/*
* If channels enable bits don't exist writing 1 will have no
* effect so we can detect and count them.
*/
+ regmap_read(priv->regmap, TIM_CCER, &ccer_backup);
regmap_set_bits(priv->regmap, TIM_CCER, TIM_CCER_CCXE);
regmap_read(priv->regmap, TIM_CCER, &ccer);
- regmap_clear_bits(priv->regmap, TIM_CCER, TIM_CCER_CCXE);
+ regmap_write(priv->regmap, TIM_CCER, ccer_backup);
- if (ccer & TIM_CCER_CC1E)
- npwm++;
-
- if (ccer & TIM_CCER_CC2E)
- npwm++;
-
- if (ccer & TIM_CCER_CC3E)
- npwm++;
-
- if (ccer & TIM_CCER_CC4E)
- npwm++;
+ npwm = hweight32(ccer & TIM_CCER_CCXE);
+ *n_enabled = hweight32(ccer_backup & TIM_CCER_CCXE);
return npwm;
}
@@ -613,7 +651,9 @@ static int stm32_pwm_probe(struct platform_device *pdev)
struct device_node *np = dev->of_node;
struct stm32_timers *ddata = dev_get_drvdata(pdev->dev.parent);
struct stm32_pwm *priv;
+ int n_enabled;
int ret;
+ int i;
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
@@ -635,7 +675,10 @@ static int stm32_pwm_probe(struct platform_device *pdev)
priv->chip.dev = dev;
priv->chip.ops = &stm32pwm_ops;
- priv->chip.npwm = stm32_pwm_detect_channels(priv);
+ priv->chip.npwm = stm32_pwm_detect_channels(priv, &n_enabled);
+
+ for (i = 0; i < n_enabled; i++)
+ clk_enable(priv->clk);
ret = pwmchip_add(&priv->chip);
if (ret < 0)
---
base-commit: ac9a78681b921877518763ba0e89202254349d1b
change-id: 20230608-pwm-stm32-get-state-4107bcadd786
Best regards,
--
Philipp Zabel <p.zabel@...gutronix.de>
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