linux-kernel - [PATCH v2] mmc: sdhci-omap: Add Support for Suspend/Resume

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Message-ID: <20200305151228.24692-1-faiz_abbas@ti.com>
Date:   Thu, 5 Mar 2020 20:42:28 +0530
From:   Faiz Abbas <faiz_abbas@...com>
To:     <linux-kernel@...r.kernel.org>, <linux-mmc@...r.kernel.org>
CC:     <ulf.hansson@...aro.org>, <kishon@...com>,
        <adrian.hunter@...el.com>, <faiz_abbas@...com>,
        <grygorii.strashko@...com>
Subject: [PATCH v2] mmc: sdhci-omap: Add Support for Suspend/Resume

Add power management ops which save and restore the driver context and
facilitate a system suspend and resume.

Signed-off-by: Faiz Abbas <faiz_abbas@...com>
---
v2:
1. Save and restore only those registers which are not written to by
   core
2. Use force_suspend()/resume() APIs instead of runtime_resume()/suspend()
   as the driver has no runtime PM support.
 drivers/mmc/host/sdhci-omap.c | 57 +++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/drivers/mmc/host/sdhci-omap.c b/drivers/mmc/host/sdhci-omap.c
index 882053151a47..989133ec74d6 100644
--- a/drivers/mmc/host/sdhci-omap.c
+++ b/drivers/mmc/host/sdhci-omap.c
@@ -108,6 +108,11 @@ struct sdhci_omap_host {
 	struct pinctrl		*pinctrl;
 	struct pinctrl_state	**pinctrl_state;
 	bool			is_tuning;
+	/* Omap specific context save */
+	u32			con;
+	u32			hctl;
+	u32			sysctl;
+	u32			capa;
 };
 
 static void sdhci_omap_start_clock(struct sdhci_omap_host *omap_host);
@@ -1232,12 +1237,64 @@ static int sdhci_omap_remove(struct platform_device *pdev)
 
 	return 0;
 }
+#ifdef CONFIG_PM_SLEEP
+static void sdhci_omap_context_save(struct sdhci_omap_host *omap_host)
+{
+	omap_host->con = sdhci_omap_readl(omap_host, SDHCI_OMAP_CON);
+	omap_host->hctl = sdhci_omap_readl(omap_host, SDHCI_OMAP_HCTL);
+	omap_host->capa = sdhci_omap_readl(omap_host, SDHCI_OMAP_CAPA);
+}
+
+static void sdhci_omap_context_restore(struct sdhci_omap_host *omap_host)
+{
+	sdhci_omap_writel(omap_host, SDHCI_OMAP_CON, omap_host->con);
+	sdhci_omap_writel(omap_host, SDHCI_OMAP_HCTL, omap_host->hctl);
+	sdhci_omap_writel(omap_host, SDHCI_OMAP_CAPA, omap_host->capa);
+}
+
+static int __maybe_unused sdhci_omap_suspend(struct device *dev)
+{
+	struct sdhci_host *host = dev_get_drvdata(dev);
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct sdhci_omap_host *omap_host = sdhci_pltfm_priv(pltfm_host);
+
+	sdhci_suspend_host(host);
+
+	sdhci_omap_context_save(omap_host);
+
+	pinctrl_pm_select_idle_state(dev);
+
+	pm_runtime_force_suspend(dev);
+
+	return 0;
+}
+
+static int __maybe_unused sdhci_omap_resume(struct device *dev)
+{
+	struct sdhci_host *host = dev_get_drvdata(dev);
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct sdhci_omap_host *omap_host = sdhci_pltfm_priv(pltfm_host);
+
+	pm_runtime_force_resume(dev);
+
+	pinctrl_pm_select_default_state(dev);
+
+	sdhci_omap_context_restore(omap_host);
+
+	sdhci_resume_host(host);
+
+	return 0;
+}
+#endif
+static SIMPLE_DEV_PM_OPS(sdhci_omap_dev_pm_ops, sdhci_omap_suspend,
+			 sdhci_omap_resume);
 
 static struct platform_driver sdhci_omap_driver = {
 	.probe = sdhci_omap_probe,
 	.remove = sdhci_omap_remove,
 	.driver = {
 		   .name = "sdhci-omap",
+		   .pm = &sdhci_omap_dev_pm_ops,
 		   .of_match_table = omap_sdhci_match,
 		  },
 };
-- 
2.19.2