[PATCH] mmc: arasan: add runtime power management support

[Kyle Copperfield]

Add runtime power management support in Arasan SDHCI driver.

This patch is largely based on the original Arasan PM patch from
https://lore.kernel.org/linux-mmc/1537283046-13985-1-git-send-email-manish.narani@xilinx.com/
that was left abandoned since 2018 for an unknown reason.

Changes made to the original patch include reducing the runtime
suspend timeout to 50 ms and reusing the runtime PM configuration
found in sdhci-of-at91 driver.

Power consumption is measurably reduced on the Pinebook Pro and
PinePhone Pro, on which the patch was tested.  More precisely,
a reduction of about 200 mW was measured on the latter.

Originally-by: Manish Narani <manish.narani at xilinx.com>
Reviewed-by: Dragan Simic <dragan.simic at gmail.com>
Tested-by: Ondrej Jirman <megous at megous.com>
Signed-off-by: Kyle Copperfield <kmcopper at danwin1210.me>
---
 drivers/mmc/host/sdhci-of-arasan.c | 88 +++++++++++++++++++++++++++++-
 1 file changed, 86 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/sdhci-of-arasan.c b/drivers/mmc/host/sdhci-of-arasan.c
index 737e2bfdedc2..63095d91a672 100644
--- a/drivers/mmc/host/sdhci-of-arasan.c
+++ b/drivers/mmc/host/sdhci-of-arasan.c
@@ -19,6 +19,7 @@
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
+#include <linux/pm_runtime.h>
 #include <linux/phy/phy.h>
 #include <linux/regmap.h>
 #include <linux/of.h>
@@ -27,6 +28,7 @@
 #include "cqhci.h"
 #include "sdhci-pltfm.h"
 
+#define SDHCI_ARASAN_AUTOSUSPEND_DELAY	50 /* ms */
 #define SDHCI_ARASAN_VENDOR_REGISTER	0x78
 
 #define SDHCI_ARASAN_ITAPDLY_REGISTER	0xF0F8
@@ -456,6 +458,70 @@ static const struct sdhci_pltfm_data sdhci_arasan_cqe_pdata = {
 			SDHCI_QUIRK2_CLOCK_DIV_ZERO_BROKEN,
 };
 
+static int __maybe_unused sdhci_arasan_runtime_suspend(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct sdhci_host *host = platform_get_drvdata(pdev);
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct sdhci_arasan_data *sdhci_arasan = sdhci_pltfm_priv(pltfm_host);
+	int ret;
+
+	if (sdhci_arasan->has_cqe) {
+		ret = cqhci_suspend(host->mmc);
+		if (ret)
+			return ret;
+	}
+
+	ret = sdhci_runtime_suspend_host(host);
+	if (ret)
+		return ret;
+
+	if (host->tuning_mode != SDHCI_TUNING_MODE_3)
+		mmc_retune_needed(host->mmc);
+
+	clk_disable(pltfm_host->clk);
+	clk_disable(sdhci_arasan->clk_ahb);
+
+	return 0;
+}
+
+static int __maybe_unused sdhci_arasan_runtime_resume(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct sdhci_host *host = platform_get_drvdata(pdev);
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct sdhci_arasan_data *sdhci_arasan = sdhci_pltfm_priv(pltfm_host);
+	int ret;
+
+	ret = clk_enable(sdhci_arasan->clk_ahb);
+	if (ret) {
+		dev_err(dev, "Cannot enable AHB clock: %d\n", ret);
+		return ret;
+	}
+
+	ret = clk_enable(pltfm_host->clk);
+	if (ret) {
+		dev_err(dev, "Cannot enable SD clock: %d\n", ret);
+		goto err_clk_ahb;
+	}
+
+	ret = sdhci_runtime_resume_host(host, 0);
+	if (ret)
+		goto err_clk_disable;
+
+	if (sdhci_arasan->has_cqe)
+		return cqhci_resume(host->mmc);
+
+	return 0;
+
+err_clk_disable:
+	clk_disable(pltfm_host->clk);
+err_clk_ahb:
+	clk_disable(sdhci_arasan->clk_ahb);
+
+	return ret;
+}
+
 #ifdef CONFIG_PM_SLEEP
 /**
  * sdhci_arasan_suspend - Suspend method for the driver
@@ -552,8 +618,10 @@ static int sdhci_arasan_resume(struct device *dev)
 }
 #endif /* ! CONFIG_PM_SLEEP */
 
-static SIMPLE_DEV_PM_OPS(sdhci_arasan_dev_pm_ops, sdhci_arasan_suspend,
-			 sdhci_arasan_resume);
+static const struct dev_pm_ops sdhci_arasan_dev_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(sdhci_arasan_suspend, sdhci_arasan_resume)
+	SET_RUNTIME_PM_OPS(sdhci_arasan_runtime_suspend,
+			   sdhci_arasan_runtime_resume, NULL) };
 
 /**
  * sdhci_arasan_sdcardclk_recalc_rate - Return the card clock rate
@@ -1681,13 +1749,25 @@ static int sdhci_arasan_probe(struct platform_device *pdev)
 			host->mmc->caps2 |= MMC_CAP2_CQE_DCMD;
 	}
 
+	pm_runtime_get_noresume(&pdev->dev);
+	pm_runtime_set_active(&pdev->dev);
+	pm_runtime_enable(&pdev->dev);
+	pm_runtime_set_autosuspend_delay(&pdev->dev, SDHCI_ARASAN_AUTOSUSPEND_DELAY);
+	pm_runtime_use_autosuspend(&pdev->dev);
+
 	ret = sdhci_arasan_add_host(sdhci_arasan);
 	if (ret)
 		goto err_add_host;
 
+	pm_runtime_put_autosuspend(&pdev->dev);
+
 	return 0;
 
 err_add_host:
+	pm_runtime_disable(&pdev->dev);
+	pm_runtime_set_suspended(&pdev->dev);
+	pm_runtime_put_noidle(&pdev->dev);
+
 	if (!IS_ERR(sdhci_arasan->phy))
 		phy_exit(sdhci_arasan->phy);
 unreg_clk:
@@ -1715,6 +1795,10 @@ static int sdhci_arasan_remove(struct platform_device *pdev)
 		phy_exit(sdhci_arasan->phy);
 	}
 
+	pm_runtime_get_sync(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+	pm_runtime_put_noidle(&pdev->dev);
+
 	sdhci_arasan_unregister_sdclk(&pdev->dev);
 
 	ret = sdhci_pltfm_unregister(pdev);
-- 
2.34.0