mtd: rawnand: tegra: Add runtime PM and OPP support

The NAND on Tegra belongs to the core power domain and we're going to
enable GENPD support for the core domain. Now NAND must be resumed using
runtime PM API in order to initialize the NAND power state. Add runtime PM
and OPP support to the NAND driver.

Reviewed-by: Ulf Hansson <[e-mail]>
Acked-by: Miquel Raynal <[e-mail]>
Signed-off-by: Dmitry Osipenko <[e-mail]>
Signed-off-by: Thierry Reding <[e-mail]>

drivers/mtd/nand/raw/tegra_nand.c

···
 #include <linux/mtd/rawnand.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
 #include <linux/reset.h>
+
+#include <soc/tegra/common.h>
 
 #define COMMAND					0x00
 #define   COMMAND_GO				BIT(31)
···
 		return -ENOMEM;
 
 	ctrl->dev = &pdev->dev;
+	platform_set_drvdata(pdev, ctrl);
 	nand_controller_init(&ctrl->controller);
 	ctrl->controller.ops = &tegra_nand_controller_ops;
 
···
 	if (IS_ERR(ctrl->clk))
 		return PTR_ERR(ctrl->clk);
 
-	err = clk_prepare_enable(ctrl->clk);
+	err = devm_tegra_core_dev_init_opp_table_common(&pdev->dev);
+	if (err)
+		return err;
+
+	/*
+	 * This driver doesn't support active power management yet,
+	 * so we will simply keep device resumed.
+	 */
+	pm_runtime_enable(&pdev->dev);
+	err = pm_runtime_resume_and_get(&pdev->dev);
 	if (err)
 		return err;
 
 	err = reset_control_reset(rst);
 	if (err) {
 		dev_err(ctrl->dev, "Failed to reset HW: %d\n", err);
-		goto err_disable_clk;
+		goto err_put_pm;
 	}
 
 	writel_relaxed(HWSTATUS_CMD_DEFAULT, ctrl->regs + HWSTATUS_CMD);
···
 			       dev_name(&pdev->dev), ctrl);
 	if (err) {
 		dev_err(ctrl->dev, "Failed to get IRQ: %d\n", err);
-		goto err_disable_clk;
+		goto err_put_pm;
 	}
 
 	writel_relaxed(DMA_MST_CTRL_IS_DONE, ctrl->regs + DMA_MST_CTRL);
 
 	err = tegra_nand_chips_init(ctrl->dev, ctrl);
 	if (err)
-		goto err_disable_clk;
-
-	platform_set_drvdata(pdev, ctrl);
+		goto err_put_pm;
 
 	return 0;
 
-err_disable_clk:
-	clk_disable_unprepare(ctrl->clk);
+err_put_pm:
+	pm_runtime_put_sync_suspend(ctrl->dev);
+	pm_runtime_force_suspend(ctrl->dev);
 	return err;
 }
 
···
 
 	nand_cleanup(chip);
 
+	pm_runtime_put_sync_suspend(ctrl->dev);
+	pm_runtime_force_suspend(ctrl->dev);
+
+	return 0;
+}
+
+static int __maybe_unused tegra_nand_runtime_resume(struct device *dev)
+{
+	struct tegra_nand_controller *ctrl = dev_get_drvdata(dev);
+	int err;
+
+	err = clk_prepare_enable(ctrl->clk);
+	if (err) {
+		dev_err(dev, "Failed to enable clock: %d\n", err);
+		return err;
+	}
+
+	return 0;
+}
+
+static int __maybe_unused tegra_nand_runtime_suspend(struct device *dev)
+{
+	struct tegra_nand_controller *ctrl = dev_get_drvdata(dev);
+
 	clk_disable_unprepare(ctrl->clk);
 
 	return 0;
 }
+
+static const struct dev_pm_ops tegra_nand_pm = {
+	SET_RUNTIME_PM_OPS(tegra_nand_runtime_suspend, tegra_nand_runtime_resume,
+			   NULL)
+};
 
 static const struct of_device_id tegra_nand_of_match[] = {
 	{ .compatible = "nvidia,tegra20-nand" },
···
 	.driver = {
 		.name = "tegra-nand",
 		.of_match_table = tegra_nand_of_match,
+		.pm = &tegra_nand_pm,
 	},
 	.probe = tegra_nand_probe,
 	.remove = tegra_nand_remove,