Input: pmic8xxx-pwrkey - migrate to regmap APIs

Use the regmap APIs for this driver instead of custom pm8xxx
APIs. This breaks this driver's dependency on the pm8xxx APIs and
allows us to easily port it to other bus protocols in the future.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/misc/pmic8xxx-pwrkey.c

@@ -18,9 +18,9 @@
 #include <linux/input.h>
 #include <linux/interrupt.h>
 #include <linux/platform_device.h>
+#include <linux/regmap.h>
 #include <linux/log2.h>
 
-#include <linux/mfd/pm8xxx/core.h>
 #include <linux/input/pmic8xxx-pwrkey.h>
 
 #define PON_CNTL_1 0x1C
@@ -88,7 +88,8 @@ static int pmic8xxx_pwrkey_probe(struct platform_device *pdev)
 	int key_press_irq = platform_get_irq(pdev, 1);
 	int err;
 	unsigned int delay;
-	u8 pon_cntl;
+	unsigned int pon_cntl;
+	struct regmap *regmap;
 	struct pmic8xxx_pwrkey *pwrkey;
 	const struct pm8xxx_pwrkey_platform_data *pdata =
 					dev_get_platdata(&pdev->dev);
@@ -103,6 +104,12 @@ static int pmic8xxx_pwrkey_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
+	regmap = dev_get_regmap(pdev->dev.parent, NULL);
+	if (!regmap) {
+		dev_err(&pdev->dev, "failed to locate regmap for the device\n");
+		return -ENODEV;
+	}
+
 	pwrkey = kzalloc(sizeof(*pwrkey), GFP_KERNEL);
 	if (!pwrkey)
 		return -ENOMEM;
@@ -123,7 +130,7 @@ static int pmic8xxx_pwrkey_probe(struct platform_device *pdev)
 	delay = (pdata->kpd_trigger_delay_us << 10) / USEC_PER_SEC;
 	delay = 1 + ilog2(delay);
 
-	err = pm8xxx_readb(pdev->dev.parent, PON_CNTL_1, &pon_cntl);
+	err = regmap_read(regmap, PON_CNTL_1, &pon_cntl);
 	if (err < 0) {
 		dev_err(&pdev->dev, "failed reading PON_CNTL_1 err=%d\n", err);
 		goto free_input_dev;
@@ -136,7 +143,7 @@ static int pmic8xxx_pwrkey_probe(struct platform_device *pdev)
 	else
 		pon_cntl &= ~PON_CNTL_PULL_UP;
 
-	err = pm8xxx_writeb(pdev->dev.parent, PON_CNTL_1, pon_cntl);
+	err = regmap_write(regmap, PON_CNTL_1, pon_cntl);
 	if (err < 0) {
 		dev_err(&pdev->dev, "failed writing PON_CNTL_1 err=%d\n", err);
 		goto free_input_dev;