mtd: rawnand: renesas: Use runtime PM instead of the raw clock API

This NAND controller is part of a well defined power domain handled by
the runtime PM core. Let's keep the harmony with the other RZ/N1 drivers
and exclusively use the runtime PM API to enable/disable the clocks.

We still need to retrieve the external clock rate in order to derive the
NAND timings, but that is not a big deal, we can still do that in the
probe and just save this value to reuse it later.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/linux-mtd/20220513104957.257721-3-miquel.raynal@bootlin.com

drivers/mtd/nand/raw/renesas-nand-controller.c

@@ -16,6 +16,7 @@
 #include <linux/mtd/rawnand.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
 #include <linux/slab.h>
 
 #define COMMAND_REG 0x00
@@ -216,8 +217,7 @@ struct rnandc {
 	struct nand_controller controller;
 	struct device *dev;
 	void __iomem *regs;
-	struct clk *hclk;
-	struct clk *eclk;
+	unsigned long ext_clk_rate;
 	unsigned long assigned_cs;
 	struct list_head chips;
 	struct nand_chip *selected_chip;
@@ -891,7 +891,7 @@ static int rnandc_setup_interface(struct nand_chip *chip, int chipnr,
 {
 	struct rnand_chip *rnand = to_rnand(chip);
 	struct rnandc *rnandc = to_rnandc(chip->controller);
-	unsigned int period_ns = 1000000000 / clk_get_rate(rnandc->eclk);
+	unsigned int period_ns = 1000000000 / rnandc->ext_clk_rate;
 	const struct nand_sdr_timings *sdr;
 	unsigned int cyc, cle, ale, bef_dly, ca_to_data;
 
@@ -1319,6 +1319,7 @@ static int rnandc_chips_init(struct rnandc *rnandc)
 static int rnandc_probe(struct platform_device *pdev)
 {
 	struct rnandc *rnandc;
+	struct clk *eclk;
 	int irq, ret;
 
 	rnandc = devm_kzalloc(&pdev->dev, sizeof(*rnandc), GFP_KERNEL);
@@ -1335,29 +1336,26 @@ static int rnandc_probe(struct platform_device *pdev)
 	if (IS_ERR(rnandc->regs))
 		return PTR_ERR(rnandc->regs);
 
-	/* APB clock */
-	rnandc->hclk = devm_clk_get(&pdev->dev, "hclk");
-	if (IS_ERR(rnandc->hclk))
-		return PTR_ERR(rnandc->hclk);
-
-	/* External NAND bus clock */
-	rnandc->eclk = devm_clk_get(&pdev->dev, "eclk");
-	if (IS_ERR(rnandc->eclk))
-		return PTR_ERR(rnandc->eclk);
-
-	ret = clk_prepare_enable(rnandc->hclk);
-	if (ret)
+	devm_pm_runtime_enable(&pdev->dev);
+	ret = pm_runtime_resume_and_get(&pdev->dev);
+	if (ret < 0)
 		return ret;
 
-	ret = clk_prepare_enable(rnandc->eclk);
-	if (ret)
-		goto disable_hclk;
+	/* The external NAND bus clock rate is needed for computing timings */
+	eclk = clk_get(&pdev->dev, "eclk");
+	if (IS_ERR(eclk)) {
+		ret = PTR_ERR(eclk);
+		goto dis_runtime_pm;
+	}
+
+	rnandc->ext_clk_rate = clk_get_rate(eclk);
+	clk_put(eclk);
 
 	rnandc_dis_interrupts(rnandc);
 	irq = platform_get_irq_optional(pdev, 0);
 	if (irq == -EPROBE_DEFER) {
 		ret = irq;
-		goto disable_eclk;
+		goto dis_runtime_pm;
 	} else if (irq < 0) {
 		dev_info(&pdev->dev, "No IRQ found, fallback to polling\n");
 		rnandc->use_polling = true;
@@ -1365,12 +1363,12 @@ static int rnandc_probe(struct platform_device *pdev)
 		ret = devm_request_irq(&pdev->dev, irq, rnandc_irq_handler, 0,
 				       "renesas-nand-controller", rnandc);
 		if (ret < 0)
-			goto disable_eclk;
+			goto dis_runtime_pm;
 	}
 
 	ret = dma_set_mask(&pdev->dev, DMA_BIT_MASK(32));
 	if (ret)
-		goto disable_eclk;
+		goto dis_runtime_pm;
 
 	rnandc_clear_fifo(rnandc);
 
@@ -1378,14 +1376,12 @@ static int rnandc_probe(struct platform_device *pdev)
 
 	ret = rnandc_chips_init(rnandc);
 	if (ret)
-		goto disable_eclk;
+		goto dis_runtime_pm;
 
 	return 0;
 
-disable_eclk:
-	clk_disable_unprepare(rnandc->eclk);
-disable_hclk:
-	clk_disable_unprepare(rnandc->hclk);
+dis_runtime_pm:
+	pm_runtime_put(&pdev->dev);
 
 	return ret;
 }
@@ -1396,8 +1392,7 @@ static int rnandc_remove(struct platform_device *pdev)
 
 	rnandc_chips_cleanup(rnandc);
 
-	clk_disable_unprepare(rnandc->eclk);
-	clk_disable_unprepare(rnandc->hclk);
+	pm_runtime_put(&pdev->dev);
 
 	return 0;
 }