spi: stm32-qspi: Add pm_runtime support

By default, STM32_AUTOSUSPEND_DELAY is set to -1 which has for
effect to prevent runtime suspends.
Runtime suspends can be activated by setting autosuspend_delay_ms using
sysfs entry :
echo {delay_in_ms} > /sys/devices/platform/soc/58003000.spi/power/autosusp
end_delay_ms)

Signed-off-by: Christophe Kerello <christophe.kerello@st.com>
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
Link: https://lore.kernel.org/r/20200417121241.6473-1-patrice.chotard@st.com
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-stm32-qspi.c

@@ -16,6 +16,7 @@
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/pinctrl/consumer.h>
+#include <linux/pm_runtime.h>
 #include <linux/platform_device.h>
 #include <linux/reset.h>
 #include <linux/sizes.h>
@@ -87,6 +88,7 @@
 #define STM32_BUSY_TIMEOUT_US 100000
 #define STM32_ABT_TIMEOUT_US 100000
 #define STM32_COMP_TIMEOUT_MS 1000
+#define STM32_AUTOSUSPEND_DELAY -1
 
 struct stm32_qspi_flash {
 	struct stm32_qspi *qspi;
@@ -431,10 +433,17 @@ static int stm32_qspi_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
 	struct stm32_qspi *qspi = spi_controller_get_devdata(mem->spi->master);
 	int ret;
 
+	ret = pm_runtime_get_sync(qspi->dev);
+	if (ret < 0)
+		return ret;
+
 	mutex_lock(&qspi->lock);
 	ret = stm32_qspi_send(mem, op);
 	mutex_unlock(&qspi->lock);
 
+	pm_runtime_mark_last_busy(qspi->dev);
+	pm_runtime_put_autosuspend(qspi->dev);
+
 	return ret;
 }
 
@@ -444,13 +453,18 @@ static int stm32_qspi_setup(struct spi_device *spi)
 	struct stm32_qspi *qspi = spi_controller_get_devdata(ctrl);
 	struct stm32_qspi_flash *flash;
 	u32 presc;
+	int ret;
 
 	if (ctrl->busy)
 		return -EBUSY;
 
 	if (!spi->max_speed_hz)
 		return -EINVAL;
 
+	ret = pm_runtime_get_sync(qspi->dev);
+	if (ret < 0)
+		return ret;
+
 	presc = DIV_ROUND_UP(qspi->clk_rate, spi->max_speed_hz) - 1;
 
 	flash = &qspi->flash[spi->chip_select];
@@ -467,6 +481,9 @@ static int stm32_qspi_setup(struct spi_device *spi)
 	writel_relaxed(qspi->dcr_reg, qspi->io_base + QSPI_DCR);
 	mutex_unlock(&qspi->lock);
 
+	pm_runtime_mark_last_busy(qspi->dev);
+	pm_runtime_put_autosuspend(qspi->dev);
+
 	return 0;
 }
 
@@ -643,9 +660,20 @@ static int stm32_qspi_probe(struct platform_device *pdev)
 	ctrl->num_chipselect = STM32_QSPI_MAX_NORCHIP;
 	ctrl->dev.of_node = dev->of_node;
 
+	pm_runtime_set_autosuspend_delay(dev, STM32_AUTOSUSPEND_DELAY);
+	pm_runtime_use_autosuspend(dev);
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+	pm_runtime_get_noresume(dev);
+
 	ret = devm_spi_register_master(dev, ctrl);
-	if (!ret)
-		return 0;
+	if (ret)
+		goto err_qspi_release;
+
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_put_autosuspend(dev);
+
+	return 0;
 
 err_qspi_release:
 	stm32_qspi_release(qspi);
@@ -660,14 +688,28 @@ static int stm32_qspi_remove(struct platform_device *pdev)
 	struct stm32_qspi *qspi = platform_get_drvdata(pdev);
 
 	stm32_qspi_release(qspi);
+
 	return 0;
 }
 
-static int __maybe_unused stm32_qspi_suspend(struct device *dev)
+static int __maybe_unused stm32_qspi_runtime_suspend(struct device *dev)
 {
 	struct stm32_qspi *qspi = dev_get_drvdata(dev);
 
 	clk_disable_unprepare(qspi->clk);
+
+	return 0;
+}
+
+static int __maybe_unused stm32_qspi_runtime_resume(struct device *dev)
+{
+	struct stm32_qspi *qspi = dev_get_drvdata(dev);
+
+	return clk_prepare_enable(qspi->clk);
+}
+
+static int __maybe_unused stm32_qspi_suspend(struct device *dev)
+{
 	pinctrl_pm_select_sleep_state(dev);
 
 	return 0;
@@ -683,10 +725,17 @@ static int __maybe_unused stm32_qspi_resume(struct device *dev)
 	writel_relaxed(qspi->cr_reg, qspi->io_base + QSPI_CR);
 	writel_relaxed(qspi->dcr_reg, qspi->io_base + QSPI_DCR);
 
+	pm_runtime_mark_last_busy(qspi->dev);
+	pm_runtime_put_autosuspend(qspi->dev);
+
 	return 0;
 }
 
-static SIMPLE_DEV_PM_OPS(stm32_qspi_pm_ops, stm32_qspi_suspend, stm32_qspi_resume);
+static const struct dev_pm_ops stm32_qspi_pm_ops = {
+	SET_RUNTIME_PM_OPS(stm32_qspi_runtime_suspend,
+			   stm32_qspi_runtime_resume, NULL)
+	SET_SYSTEM_SLEEP_PM_OPS(stm32_qspi_suspend, stm32_qspi_resume)
+};
 
 static const struct of_device_id stm32_qspi_match[] = {
 	{.compatible = "st,stm32f469-qspi"},