gpio: exar: switch to using regmap

We can simplify the code in gpio-exar by using regmap. This allows us to
drop the mutex (regmap provides its own locking) and we can also reuse
regmap's bit operations instead of implementing our own update function.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Author: brgl

drivers/gpio/Kconfig

@@ -255,6 +255,7 @@ config GPIO_EP93XX
 config GPIO_EXAR
 	tristate "Support for GPIO pins on XR17V352/354/358"
 	depends on SERIAL_8250_EXAR
+	select REGMAP_MMIO
 	help
 	  Selecting this option will enable handling of GPIO pins present
 	  on Exar XR17V352/354/358 chips.

drivers/gpio/gpio-exar.c

@@ -14,6 +14,7 @@
 #include <linux/module.h>
 #include <linux/pci.h>
 #include <linux/platform_device.h>
+#include <linux/regmap.h>
 
 #define EXAR_OFFSET_MPIOLVL_LO 0x90
 #define EXAR_OFFSET_MPIOSEL_LO 0x93
@@ -26,9 +27,8 @@ static DEFINE_IDA(ida_index);
 
 struct exar_gpio_chip {
 	struct gpio_chip gpio_chip;
-	struct mutex lock;
+	struct regmap *regmap;
 	int index;
-	void __iomem *regs;
 	char name[20];
 	unsigned int first_pin;
 };
@@ -53,51 +53,13 @@ exar_offset_to_bit(struct exar_gpio_chip *exar_gpio, unsigned int offset)
 	return (offset + exar_gpio->first_pin) % 8;
 }
 
-static void exar_update(struct gpio_chip *chip, unsigned int reg, int val,
-			unsigned int offset)
-{
-	struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
-	int temp;
-
-	mutex_lock(&exar_gpio->lock);
-	temp = readb(exar_gpio->regs + reg);
-	temp &= ~BIT(offset);
-	if (val)
-		temp |= BIT(offset);
-	writeb(temp, exar_gpio->regs + reg);
-	mutex_unlock(&exar_gpio->lock);
-}
-
-static int exar_set_direction(struct gpio_chip *chip, int direction,
-			      unsigned int offset)
-{
-	struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
-	unsigned int addr = exar_offset_to_sel_addr(exar_gpio, offset);
-	unsigned int bit = exar_offset_to_bit(exar_gpio, offset);
-
-	exar_update(chip, addr, direction, bit);
-	return 0;
-}
-
-static int exar_get(struct gpio_chip *chip, unsigned int reg)
-{
-	struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
-	int value;
-
-	mutex_lock(&exar_gpio->lock);
-	value = readb(exar_gpio->regs + reg);
-	mutex_unlock(&exar_gpio->lock);
-
-	return value;
-}
-
 static int exar_get_direction(struct gpio_chip *chip, unsigned int offset)
 {
 	struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
 	unsigned int addr = exar_offset_to_sel_addr(exar_gpio, offset);
 	unsigned int bit = exar_offset_to_bit(exar_gpio, offset);
 
-	if (exar_get(chip, addr) & BIT(bit))
+	if (regmap_test_bits(exar_gpio->regmap, addr, BIT(bit)))
 		return GPIO_LINE_DIRECTION_IN;
 
 	return GPIO_LINE_DIRECTION_OUT;
@@ -109,7 +71,7 @@ static int exar_get_value(struct gpio_chip *chip, unsigned int offset)
 	unsigned int addr = exar_offset_to_lvl_addr(exar_gpio, offset);
 	unsigned int bit = exar_offset_to_bit(exar_gpio, offset);
 
-	return !!(exar_get(chip, addr) & BIT(bit));
+	return !!(regmap_test_bits(exar_gpio->regmap, addr, BIT(bit)));
 }
 
 static void exar_set_value(struct gpio_chip *chip, unsigned int offset,
@@ -119,21 +81,42 @@ static void exar_set_value(struct gpio_chip *chip, unsigned int offset,
 	unsigned int addr = exar_offset_to_lvl_addr(exar_gpio, offset);
 	unsigned int bit = exar_offset_to_bit(exar_gpio, offset);
 
-	exar_update(chip, addr, value, bit);
+	if (value)
+		regmap_set_bits(exar_gpio->regmap, addr, BIT(bit));
+	else
+		regmap_clear_bits(exar_gpio->regmap, addr, BIT(bit));
 }
 
 static int exar_direction_output(struct gpio_chip *chip, unsigned int offset,
 				 int value)
 {
+	struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
+	unsigned int addr = exar_offset_to_sel_addr(exar_gpio, offset);
+	unsigned int bit = exar_offset_to_bit(exar_gpio, offset);
+
 	exar_set_value(chip, offset, value);
-	return exar_set_direction(chip, 0, offset);
+	regmap_clear_bits(exar_gpio->regmap, addr, BIT(bit));
+
+	return 0;
 }
 
 static int exar_direction_input(struct gpio_chip *chip, unsigned int offset)
 {
-	return exar_set_direction(chip, 1, offset);
+	struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
+	unsigned int addr = exar_offset_to_sel_addr(exar_gpio, offset);
+	unsigned int bit = exar_offset_to_bit(exar_gpio, offset);
+
+	regmap_set_bits(exar_gpio->regmap, addr, BIT(bit));
+
+	return 0;
 }
 
+static const struct regmap_config exar_regmap_config = {
+	.name		= "exar-gpio",
+	.reg_bits	= 16,
+	.val_bits	= 8,
+};
+
 static int gpio_exar_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -163,13 +146,17 @@ static int gpio_exar_probe(struct platform_device *pdev)
 	if (!exar_gpio)
 		return -ENOMEM;
 
-	mutex_init(&exar_gpio->lock);
+	/*
+	 * We don't need to check the return values of mmio regmap operations (unless
+	 * the regmap has a clock attached which is not the case here).
+	 */
+	exar_gpio->regmap = devm_regmap_init_mmio(dev, p, &exar_regmap_config);
+	if (IS_ERR(exar_gpio->regmap))
+		return PTR_ERR(exar_gpio->regmap);
 
 	index = ida_alloc(&ida_index, GFP_KERNEL);
-	if (index < 0) {
-		ret = index;
-		goto err_mutex_destroy;
-	}
+	if (index < 0)
+		return index;
 
 	sprintf(exar_gpio->name, "exar_gpio%d", index);
 	exar_gpio->gpio_chip.label = exar_gpio->name;
@@ -181,7 +168,6 @@ static int gpio_exar_probe(struct platform_device *pdev)
 	exar_gpio->gpio_chip.set = exar_set_value;
 	exar_gpio->gpio_chip.base = -1;
 	exar_gpio->gpio_chip.ngpio = ngpios;
-	exar_gpio->regs = p;
 	exar_gpio->index = index;
 	exar_gpio->first_pin = first_pin;
 
@@ -195,8 +181,6 @@ static int gpio_exar_probe(struct platform_device *pdev)
 
 err_destroy:
 	ida_free(&ida_index, index);
-err_mutex_destroy:
-	mutex_destroy(&exar_gpio->lock);
 	return ret;
 }
 
@@ -205,7 +189,6 @@ static int gpio_exar_remove(struct platform_device *pdev)
 	struct exar_gpio_chip *exar_gpio = platform_get_drvdata(pdev);
 
 	ida_free(&ida_index, exar_gpio->index);
-	mutex_destroy(&exar_gpio->lock);
 
 	return 0;
 }