mmc: sdhci-of-at91: set clocks and presets after resume from deepest PM

This adds deepest (Backup+Self-Refresh) PM support to the ATMEL SAMA5D2
SoC's SDHCI controller.

When resuming from deepest state, it is required to restore preset
registers as the registers are lost since VDD core has been shut down
when entering deepest state on the SAMA5D2. The clocks need to be
reconfigured as well.

The other registers and init process are taken care of by the SDHCI
core.

Signed-off-by: Quentin Schulz <quentin.schulz@free-electrons.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci-of-at91.c

@@ -42,6 +42,7 @@ struct sdhci_at91_priv {
 	struct clk *hclock;
 	struct clk *gck;
 	struct clk *mainck;
+	bool restore_needed;
 };
 
 static void sdhci_at91_set_force_card_detect(struct sdhci_host *host)
@@ -224,6 +225,22 @@ static int sdhci_at91_set_clks_presets(struct device *dev)
 	return 0;
 }
 
+#ifdef CONFIG_PM_SLEEP
+static int sdhci_at91_suspend(struct device *dev)
+{
+	struct sdhci_host *host = dev_get_drvdata(dev);
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct sdhci_at91_priv *priv = sdhci_pltfm_priv(pltfm_host);
+	int ret;
+
+	ret = pm_runtime_force_suspend(dev);
+
+	priv->restore_needed = true;
+
+	return ret;
+}
+#endif /* CONFIG_PM_SLEEP */
+
 #ifdef CONFIG_PM
 static int sdhci_at91_runtime_suspend(struct device *dev)
 {
@@ -251,6 +268,15 @@ static int sdhci_at91_runtime_resume(struct device *dev)
 	struct sdhci_at91_priv *priv = sdhci_pltfm_priv(pltfm_host);
 	int ret;
 
+	if (priv->restore_needed) {
+		ret = sdhci_at91_set_clks_presets(dev);
+		if (ret)
+			return ret;
+
+		priv->restore_needed = false;
+		goto out;
+	}
+
 	ret = clk_prepare_enable(priv->mainck);
 	if (ret) {
 		dev_err(dev, "can't enable mainck\n");
@@ -269,13 +295,13 @@ static int sdhci_at91_runtime_resume(struct device *dev)
 		return ret;
 	}
 
+out:
 	return sdhci_runtime_resume_host(host);
 }
 #endif /* CONFIG_PM */
 
 static const struct dev_pm_ops sdhci_at91_dev_pm_ops = {
-	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
-				pm_runtime_force_resume)
+	SET_SYSTEM_SLEEP_PM_OPS(sdhci_at91_suspend, pm_runtime_force_resume)
 	SET_RUNTIME_PM_OPS(sdhci_at91_runtime_suspend,
 			   sdhci_at91_runtime_resume,
 			   NULL)
@@ -324,6 +350,8 @@ static int sdhci_at91_probe(struct platform_device *pdev)
 	if (ret)
 		goto sdhci_pltfm_free;
 
+	priv->restore_needed = false;
+
 	ret = mmc_of_parse(host->mmc);
 	if (ret)
 		goto clocks_disable_unprepare;