ata: ahci-imx: Covert to use GPIO descriptor

This converts the i.MX AHCI driver to use a GPIO descriptor
instead of parsing the device tree by itself.

This driver is quite obviously device tree only, and the
GPIO line is treated as optional, so let's keep it as
optional.

None of the device trees in the kernel use this GPIO
facility today, so it is hard to test.

Cc: Egor Starkov <[e-mail]>
Cc: Richard Zhu <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

drivers/ata/ahci_imx.c

···
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
 #include <linux/ahci_platform.h>
+#include <linux/gpio/consumer.h>
 #include <linux/of_device.h>
-#include <linux/of_gpio.h>
 #include <linux/mfd/syscon.h>
 #include <linux/mfd/syscon/imx6q-iomuxc-gpr.h>
 #include <linux/libata.h>
···
 	struct clk *phy_pclk0;
 	struct clk *phy_pclk1;
 	void __iomem *phy_base;
-	int clkreq_gpio;
+	struct gpio_desc *clkreq_gpiod;
 	struct regmap *gpr;
 	bool no_device;
 	bool first_time;
···
 
 static int imx8_sata_probe(struct device *dev, struct imx_ahci_priv *imxpriv)
 {
-	int ret;
 	struct resource *phy_res;
 	struct platform_device *pdev = imxpriv->ahci_pdev;
 	struct device_node *np = dev->of_node;
···
 	}
 
 	/* Fetch GPIO, then enable the external OSC */
-	imxpriv->clkreq_gpio = of_get_named_gpio(np, "clkreq-gpio", 0);
-	if (gpio_is_valid(imxpriv->clkreq_gpio)) {
-		ret = devm_gpio_request_one(dev, imxpriv->clkreq_gpio,
-					    GPIOF_OUT_INIT_LOW,
-					    "SATA CLKREQ");
-		if (ret == -EBUSY) {
-			dev_info(dev, "clkreq had been initialized.\n");
-		} else if (ret) {
-			dev_err(dev, "%d unable to get clkreq.\n", ret);
-			return ret;
-		}
-	} else if (imxpriv->clkreq_gpio == -EPROBE_DEFER) {
-		return imxpriv->clkreq_gpio;
-	}
+	imxpriv->clkreq_gpiod = devm_gpiod_get_optional(dev, "clkreq",
+				GPIOD_OUT_LOW | GPIOD_FLAGS_BIT_NONEXCLUSIVE);
+	if (IS_ERR(imxpriv->clkreq_gpiod))
+		return PTR_ERR(imxpriv->clkreq_gpiod);
+	if (imxpriv->clkreq_gpiod)
+		gpiod_set_consumer_name(imxpriv->clkreq_gpiod, "SATA CLKREQ");
 
 	return 0;
 }