gpio: zynq: Provided workaround for GPIO

This patch provides workaround in the gpio driver
for Zynq and ZynqMP Platforms by reading pin value
of EMIO banks through DATA register as it was unable
to read the value of it from DATA_RO register.

Signed-off-by: Swapna Manupati <swapnam@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-zynq.c

@@ -67,6 +67,7 @@
 /* MSW Mask & Data -WO */
 #define ZYNQ_GPIO_DATA_MSW_OFFSET(BANK)	(0x004 + (8 * BANK))
 /* Data Register-RW */
+#define ZYNQ_GPIO_DATA_OFFSET(BANK)	(0x040 + (4 * BANK))
 #define ZYNQ_GPIO_DATA_RO_OFFSET(BANK)	(0x060 + (4 * BANK))
 /* Direction mode reg-RW */
 #define ZYNQ_GPIO_DIRM_OFFSET(BANK)	(0x204 + (0x40 * BANK))
@@ -98,6 +99,7 @@
 
 /* set to differentiate zynq from zynqmp, 0=zynqmp, 1=zynq */
 #define ZYNQ_GPIO_QUIRK_IS_ZYNQ	BIT(0)
+#define GPIO_QUIRK_DATA_RO_BUG	BIT(1)
 
 struct gpio_regs {
 	u32 datamsw[ZYNQMP_GPIO_MAX_BANK];
@@ -159,6 +161,17 @@ static int zynq_gpio_is_zynq(struct zynq_gpio *gpio)
 	return !!(gpio->p_data->quirks & ZYNQ_GPIO_QUIRK_IS_ZYNQ);
 }
 
+/**
+ * gpio_data_ro_bug - test if HW bug exists or not
+ * @gpio:       Pointer to driver data struct
+ *
+ * Return: 0 if bug doesnot exist, 1 if bug exists.
+ */
+static int gpio_data_ro_bug(struct zynq_gpio *gpio)
+{
+	return !!(gpio->p_data->quirks & GPIO_QUIRK_DATA_RO_BUG);
+}
+
 /**
  * zynq_gpio_get_bank_pin - Get the bank number and pin number within that bank
  * for a given pin in the GPIO device
@@ -210,9 +223,28 @@ static int zynq_gpio_get_value(struct gpio_chip *chip, unsigned int pin)
 
 	zynq_gpio_get_bank_pin(pin, &bank_num, &bank_pin_num, gpio);
 
-	data = readl_relaxed(gpio->base_addr +
-			     ZYNQ_GPIO_DATA_RO_OFFSET(bank_num));
-
+	if (gpio_data_ro_bug(gpio)) {
+		if (zynq_gpio_is_zynq(gpio)) {
+			if (bank_num <= 1) {
+				data = readl_relaxed(gpio->base_addr +
+					ZYNQ_GPIO_DATA_RO_OFFSET(bank_num));
+			} else {
+				data = readl_relaxed(gpio->base_addr +
+					ZYNQ_GPIO_DATA_OFFSET(bank_num));
+			}
+		} else {
+			if (bank_num <= 2) {
+				data = readl_relaxed(gpio->base_addr +
+					ZYNQ_GPIO_DATA_RO_OFFSET(bank_num));
+			} else {
+				data = readl_relaxed(gpio->base_addr +
+					ZYNQ_GPIO_DATA_OFFSET(bank_num));
+			}
+		}
+	} else {
+		data = readl_relaxed(gpio->base_addr +
+			ZYNQ_GPIO_DATA_RO_OFFSET(bank_num));
+	}
 	return (data >> bank_pin_num) & 1;
 }
 
@@ -704,6 +736,7 @@ static const struct dev_pm_ops zynq_gpio_dev_pm_ops = {
 
 static const struct zynq_platform_data zynqmp_gpio_def = {
 	.label = "zynqmp_gpio",
+	.quirks = GPIO_QUIRK_DATA_RO_BUG,
 	.ngpio = ZYNQMP_GPIO_NR_GPIOS,
 	.max_bank = ZYNQMP_GPIO_MAX_BANK,
 	.bank_min[0] = ZYNQ_GPIO_BANK0_PIN_MIN(MP),
@@ -722,7 +755,7 @@ static const struct zynq_platform_data zynqmp_gpio_def = {
 
 static const struct zynq_platform_data zynq_gpio_def = {
 	.label = "zynq_gpio",
-	.quirks = ZYNQ_GPIO_QUIRK_IS_ZYNQ,
+	.quirks = ZYNQ_GPIO_QUIRK_IS_ZYNQ | GPIO_QUIRK_DATA_RO_BUG,
 	.ngpio = ZYNQ_GPIO_NR_GPIOS,
 	.max_bank = ZYNQ_GPIO_MAX_BANK,
 	.bank_min[0] = ZYNQ_GPIO_BANK0_PIN_MIN(),