So far, even if our card was not in use, we didn't shut down our MMC
controller, which meant that it was still active and clocking the bus.

While this obviously means that we could save some power there, it also
creates issues when it comes to EMC control since we'll have a perfect peak
at the card clock rate.

Let's implement runtime_pm with autosuspend so that we will shut down the
controller when it's not been in use for quite some time.

Signed-off-by: Maxime Ripard <redacted>
---
 drivers/mmc/host/sunxi-mmc.c | 48 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 48 insertions(+)

diff --git a/drivers/mmc/host/sunxi-mmc.c b/drivers/mmc/host/sunxi-mmc.c
index 0165da0d022a..0253deb153a4 100644
--- a/drivers/mmc/host/sunxi-mmc.c
+++ b/drivers/mmc/host/sunxi-mmc.c

@@ -35,6 +35,7 @@
 #include <linux/of_gpio.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
 #include <linux/regulator/consumer.h>
 #include <linux/reset.h>
 #include <linux/scatterlist.h>

@@ -969,6 +970,9 @@ static void sunxi_mmc_enable_sdio_irq(struct mmc_host *mmc, int enable)
 	unsigned long flags;
 	u32 imask;
 
+	if (enable)
+		pm_runtime_get_noresume(host->dev);
+
 	spin_lock_irqsave(&host->lock, flags);
 
 	imask = mmc_readl(host, REG_IMASK);

@@ -981,6 +985,9 @@ static void sunxi_mmc_enable_sdio_irq(struct mmc_host *mmc, int enable)
 	}
 	mmc_writel(host, REG_IMASK, imask);
 	spin_unlock_irqrestore(&host->lock, flags);
+
+	if (!enable)
+		pm_runtime_put_noidle(host->mmc->parent);
 }
 
 static void sunxi_mmc_hw_reset(struct mmc_host *mmc)

@@ -1394,6 +1401,11 @@ static int sunxi_mmc_probe(struct platform_device *pdev)
 	if (ret)
 		goto error_free_dma;
 
+	pm_runtime_set_active(&pdev->dev);
+	pm_runtime_set_autosuspend_delay(&pdev->dev, 50);
+	pm_runtime_use_autosuspend(&pdev->dev);
+	pm_runtime_enable(&pdev->dev);
+
 	ret = mmc_add_host(mmc);
 	if (ret)
 		goto error_free_dma;

@@ -1414,6 +1426,7 @@ static int sunxi_mmc_remove(struct platform_device *pdev)
 	struct sunxi_mmc_host *host = mmc_priv(mmc);
 
 	mmc_remove_host(mmc);
+	pm_runtime_force_suspend(&pdev->dev);
 	disable_irq(host->irq);
 	sunxi_mmc_disable(host);
 	dma_free_coherent(&pdev->dev, PAGE_SIZE, host->sg_cpu, host->sg_dma);

@@ -1422,10 +1435,45 @@ static int sunxi_mmc_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static int sunxi_mmc_runtime_resume(struct device *dev)
+{
+	struct mmc_host	*mmc = dev_get_drvdata(dev);
+	struct sunxi_mmc_host *host = mmc_priv(mmc);
+	int ret;
+
+	ret = sunxi_mmc_enable(host);
+	if (ret)
+		return ret;
+
+	sunxi_mmc_init_host(host);
+	sunxi_mmc_set_bus_width(host, mmc->ios.bus_width);
+	sunxi_mmc_set_clk(host, &mmc->ios);
+
+	return 0;
+}
+
+static int sunxi_mmc_runtime_suspend(struct device *dev)
+{
+	struct mmc_host	*mmc = dev_get_drvdata(dev);
+	struct sunxi_mmc_host *host = mmc_priv(mmc);
+
+	sunxi_mmc_reset_host(host);
+	sunxi_mmc_disable(host);
+
+	return 0;
+}
+
+static const struct dev_pm_ops sunxi_mmc_pm_ops = {
+	SET_RUNTIME_PM_OPS(sunxi_mmc_runtime_suspend,
+			   sunxi_mmc_runtime_resume,
+			   NULL)
+};
+
 static struct platform_driver sunxi_mmc_driver = {
 	.driver = {
 		.name	= "sunxi-mmc",
 		.of_match_table = of_match_ptr(sunxi_mmc_of_match),
+		.pm = &sunxi_mmc_pm_ops,
 	},
 	.probe		= sunxi_mmc_probe,
 	.remove		= sunxi_mmc_remove,