mtd: rawnand: denali_dt: add more clocks based on IP datasheet

Currently, denali_dt.c requires a single anonymous clock, but
the Denali User's Guide requires three clocks for this IP:

 - clk: controller core clock

 - clk_x: bus interface clock

 - ecc_clk: clock at which ECC circuitry is run

This commit supports these named clocks to represent the real hardware.

For the backward compatibility, the driver still accepts a single clock
just as before.  The clk_x_rate is taken from the clock driver again if
the named clock "clk_x" is available.  This will happen only for future
DT, hence the existing DT files are not affected.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Richard Weinberger <richard@nod.at>
Tested-by: Richard Weinberger <richard@nod.at>
Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

drivers/mtd/nand/raw/denali_dt.c

@@ -27,7 +27,9 @@
 
 struct denali_dt {
 	struct denali_nand_info	denali;
-	struct clk		*clk;
+	struct clk *clk;	/* core clock */
+	struct clk *clk_x;	/* bus interface clock */
+	struct clk *clk_ecc;	/* ECC circuit clock */
 };
 
 struct denali_dt_data {
@@ -115,28 +117,61 @@ static int denali_dt_probe(struct platform_device *pdev)
 	if (IS_ERR(denali->host))
 		return PTR_ERR(denali->host);
 
-	dt->clk = devm_clk_get(dev, NULL);
+	/*
+	 * A single anonymous clock is supported for the backward compatibility.
+	 * New platforms should support all the named clocks.
+	 */
+	dt->clk = devm_clk_get(dev, "nand");
+	if (IS_ERR(dt->clk))
+		dt->clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(dt->clk)) {
 		dev_err(dev, "no clk available\n");
 		return PTR_ERR(dt->clk);
 	}
+
+	dt->clk_x = devm_clk_get(dev, "nand_x");
+	if (IS_ERR(dt->clk_x))
+		dt->clk_x = NULL;
+
+	dt->clk_ecc = devm_clk_get(dev, "ecc");
+	if (IS_ERR(dt->clk_ecc))
+		dt->clk_ecc = NULL;
+
 	ret = clk_prepare_enable(dt->clk);
 	if (ret)
 		return ret;
 
-	/*
-	 * Hardcode the clock rate for the backward compatibility.
-	 * This works for both SOCFPGA and UniPhier.
-	 */
-	denali->clk_x_rate = 200000000;
+	ret = clk_prepare_enable(dt->clk_x);
+	if (ret)
+		goto out_disable_clk;
+
+	ret = clk_prepare_enable(dt->clk_ecc);
+	if (ret)
+		goto out_disable_clk_x;
+
+	if (dt->clk_x) {
+		denali->clk_x_rate = clk_get_rate(dt->clk_x);
+	} else {
+		/*
+		 * Hardcode the clock rates for the backward compatibility.
+		 * This works for both SOCFPGA and UniPhier.
+		 */
+		dev_notice(dev,
+			   "necessary clock is missing. default clock rates are used.\n");
+		denali->clk_x_rate = 200000000;
+	}
 
 	ret = denali_init(denali);
 	if (ret)
-		goto out_disable_clk;
+		goto out_disable_clk_ecc;
 
 	platform_set_drvdata(pdev, dt);
 	return 0;
 
+out_disable_clk_ecc:
+	clk_disable_unprepare(dt->clk_ecc);
+out_disable_clk_x:
+	clk_disable_unprepare(dt->clk_x);
 out_disable_clk:
 	clk_disable_unprepare(dt->clk);
 
@@ -148,6 +183,8 @@ static int denali_dt_remove(struct platform_device *pdev)
 	struct denali_dt *dt = platform_get_drvdata(pdev);
 
 	denali_remove(&dt->denali);
+	clk_disable_unprepare(dt->clk_ecc);
+	clk_disable_unprepare(dt->clk_x);
 	clk_disable_unprepare(dt->clk);
 
 	return 0;