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>

diff --git a/drivers/iio/counter/stm32-lptimer-cnt.c b/drivers/iio/counter/stm32-lptimer-cnt.c
index 42fb8ba670903a9450dc77fb1d04efd13e69546f..2a49cce0edb439465690def17865593651898959 100644 (file)
--- 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 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);