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Subject[PATCH 4/4] iio: counter: stm32-lptimer: Add power management support
Date
Add suspend/resume PM sleep ops. When going to low power, disable
active counter. Only active counter should be resumed: don't touch
disabled counter, as it may be used by other LPTimer MFD child driver.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
drivers/iio/counter/stm32-lptimer-cnt.c | 55 +++++++++++++++++++++++++++++++++
1 file changed, 55 insertions(+)

diff --git a/drivers/iio/counter/stm32-lptimer-cnt.c b/drivers/iio/counter/stm32-lptimer-cnt.c
index 42fb8ba..2a49cce 100644
--- a/drivers/iio/counter/stm32-lptimer-cnt.c
+++ b/drivers/iio/counter/stm32-lptimer-cnt.c
@@ -14,6 +14,7 @@
#include <linux/iio/iio.h>
#include <linux/mfd/stm32-lptimer.h>
#include <linux/module.h>
+#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>

struct stm32_lptim_cnt {
@@ -23,6 +24,7 @@ struct stm32_lptim_cnt {
u32 preset;
u32 polarity;
u32 quadrature_mode;
+ bool enabled;
};

static int stm32_lptim_is_enabled(struct stm32_lptim_cnt *priv)
@@ -50,6 +52,7 @@ static int stm32_lptim_set_enable_state(struct stm32_lptim_cnt *priv,

if (!enable) {
clk_disable(priv->clk);
+ priv->enabled = false;
return 0;
}

@@ -79,6 +82,7 @@ static int stm32_lptim_set_enable_state(struct stm32_lptim_cnt *priv,
regmap_write(priv->regmap, STM32_LPTIM_CR, 0);
return ret;
}
+ priv->enabled = true;

/* Start LP timer in continuous mode */
return regmap_update_bits(priv->regmap, STM32_LPTIM_CR,
@@ -361,6 +365,56 @@ static int stm32_lptim_cnt_probe(struct platform_device *pdev)
return devm_iio_device_register(&pdev->dev, indio_dev);
}

+#ifdef CONFIG_PM_SLEEP
+static int stm32_lptim_cnt_suspend(struct device *dev)
+{
+ struct stm32_lptim_cnt *priv = dev_get_drvdata(dev);
+ int ret;
+
+ /* Only take care of enabled counter: don't disturb other MFD child */
+ if (priv->enabled) {
+ ret = stm32_lptim_setup(priv, 0);
+ if (ret)
+ return ret;
+
+ ret = stm32_lptim_set_enable_state(priv, 0);
+ if (ret)
+ return ret;
+
+ /* Force enable state for later resume */
+ priv->enabled = true;
+ }
+
+ return pinctrl_pm_select_sleep_state(dev);
+}
+
+static int stm32_lptim_cnt_resume(struct device *dev)
+{
+ struct stm32_lptim_cnt *priv = dev_get_drvdata(dev);
+ int ret;
+
+ ret = pinctrl_pm_select_default_state(dev);
+ if (ret)
+ return ret;
+
+ if (priv->enabled) {
+ priv->enabled = false;
+ ret = stm32_lptim_setup(priv, 1);
+ if (ret)
+ return ret;
+
+ ret = stm32_lptim_set_enable_state(priv, 1);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(stm32_lptim_cnt_pm_ops, stm32_lptim_cnt_suspend,
+ stm32_lptim_cnt_resume);
+
static const struct of_device_id stm32_lptim_cnt_of_match[] = {
{ .compatible = "st,stm32-lptimer-counter", },
{},
@@ -372,6 +426,7 @@ static int stm32_lptim_cnt_probe(struct platform_device *pdev)
.driver = {
.name = "stm32-lptimer-counter",
.of_match_table = stm32_lptim_cnt_of_match,
+ .pm = &stm32_lptim_cnt_pm_ops,
},
};
module_platform_driver(stm32_lptim_cnt_driver);
--
1.9.1
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