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iio: counter: stm32-lptimer: Add power management support 

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>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
hifive-unleashed-5.2
Fabrice Gasnier 2019-02-25 11:42:47 +01:00 committed by Jonathan Cameron
parent 74896202df
commit 6dc3e36fbc
1 changed files with 55 additions and 0 deletions
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55
drivers/iio/counter/stm32-lptimer-cnt.c
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@ -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 struct platform_driver stm32_lptim_cnt_driver = {
.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);