[PATCH v3 1/2] gpio: Add driver for Zynq GPIO controller

[Harini Katakam <harinik@xxxxxxxxxx>]

From: Harini Katakam <harini.katakam@xxxxxxxxxx>

Add support for GPIO controller used by Xilinx Zynq.

Signed-off-by: Harini Katakam <harinik@xxxxxxxxxx>
Signed-off-by: Soren Brinkmann <soren.brinkmann@xxxxxxxxxx>
---

v3 changes:
 - Use linux/gpio/driver.h instead of linux/gpio.h
 - Make irq a local variable in probe

v2 changes:
 - convert to pm_runtime_force_(suspend|resume)
 - add pm_runtime_set_active in probe()
 - also (un)prepare clocks when they are dis-/enabled
 - add some missing calls to pm_runtime_get()
 - use pm_runtime_put() instead of sync variant
 - remove gpio chip in driver remove()
 - remove redundant type casts
 - directly use IO helpers
 - use BIT macro to set/clear bits
 - migrate to GPIOLIB_IRQCHIP

---
 drivers/gpio/Kconfig     |    7 +
 drivers/gpio/Makefile    |    1 +
 drivers/gpio/gpio-zynq.c |  649 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 657 insertions(+)
 create mode 100644 drivers/gpio/gpio-zynq.c

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 4a1b511..bdeef02 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -340,6 +340,13 @@ config GPIO_XILINX
 	help
 	  Say yes here to support the Xilinx FPGA GPIO device
 
+config GPIO_ZYNQ
+	tristate "Xilinx Zynq GPIO support"
+	depends on ARCH_ZYNQ
+	select GPIOLIB_IRQCHIP
+	help
+	  Say yes here to support Xilinx Zynq GPIO controller.
+
 config GPIO_XTENSA
 	bool "Xtensa GPIO32 support"
 	depends on XTENSA
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index d10f6a9..033fd7c 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -101,3 +101,4 @@ obj-$(CONFIG_GPIO_WM8994)	+= gpio-wm8994.o
 obj-$(CONFIG_GPIO_XILINX)	+= gpio-xilinx.o
 obj-$(CONFIG_GPIO_XTENSA)	+= gpio-xtensa.o
 obj-$(CONFIG_GPIO_ZEVIO)	+= gpio-zevio.o
+obj-$(CONFIG_GPIO_ZYNQ)		+= gpio-zynq.o
diff --git a/drivers/gpio/gpio-zynq.c b/drivers/gpio/gpio-zynq.c
new file mode 100644
index 0000000..c0c53fd
--- /dev/null
+++ b/drivers/gpio/gpio-zynq.c
@@ -0,0 +1,649 @@
+/*
+ * Xilinx Zynq GPIO device driver
+ *
+ * Copyright (C) 2009 - 2014 Xilinx, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 2 of the License, or (at your option) any later
+ * version.
+ */
+
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/gpio/driver.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+
+#define DRIVER_NAME "zynq-gpio"
+
+/* Maximum banks */
+#define ZYNQ_GPIO_MAX_BANK	4
+
+#define ZYNQ_GPIO_BANK0_NGPIO	32
+#define ZYNQ_GPIO_BANK1_NGPIO	22
+#define ZYNQ_GPIO_BANK2_NGPIO	32
+#define ZYNQ_GPIO_BANK3_NGPIO	32
+
+#define ZYNQ_GPIO_NR_GPIOS	(ZYNQ_GPIO_BANK0_NGPIO + \
+				 ZYNQ_GPIO_BANK1_NGPIO + \
+				 ZYNQ_GPIO_BANK2_NGPIO + \
+				 ZYNQ_GPIO_BANK3_NGPIO)
+
+#define ZYNQ_GPIO_BANK0_PIN_MIN	0
+#define ZYNQ_GPIO_BANK0_PIN_MAX	(ZYNQ_GPIO_BANK0_PIN_MIN + \
+					ZYNQ_GPIO_BANK0_NGPIO - 1)
+#define ZYNQ_GPIO_BANK1_PIN_MIN	(ZYNQ_GPIO_BANK0_PIN_MAX + 1)
+#define ZYNQ_GPIO_BANK1_PIN_MAX	(ZYNQ_GPIO_BANK1_PIN_MIN + \
+					ZYNQ_GPIO_BANK1_NGPIO - 1)
+#define ZYNQ_GPIO_BANK2_PIN_MIN	(ZYNQ_GPIO_BANK1_PIN_MAX + 1)
+#define ZYNQ_GPIO_BANK2_PIN_MAX	(ZYNQ_GPIO_BANK2_PIN_MIN + \
+					ZYNQ_GPIO_BANK2_NGPIO - 1)
+#define ZYNQ_GPIO_BANK3_PIN_MIN	(ZYNQ_GPIO_BANK2_PIN_MAX + 1)
+#define ZYNQ_GPIO_BANK3_PIN_MAX	(ZYNQ_GPIO_BANK3_PIN_MIN + \
+					ZYNQ_GPIO_BANK3_NGPIO - 1)
+
+
+/* Register offsets for the GPIO device */
+/* LSW Mask & Data -WO */
+#define ZYNQ_GPIO_DATA_LSW_OFFSET(BANK)	(0x000 + (8 * BANK))
+/* MSW Mask & Data -WO */
+#define ZYNQ_GPIO_DATA_MSW_OFFSET(BANK)	(0x004 + (8 * BANK))
+/* Data Register-RW */
+#define ZYNQ_GPIO_DATA_RO_OFFSET(BANK)	(0x060 + (4 * BANK))
+/* Direction mode reg-RW */
+#define ZYNQ_GPIO_DIRM_OFFSET(BANK)	(0x204 + (0x40 * BANK))
+/* Output enable reg-RW */
+#define ZYNQ_GPIO_OUTEN_OFFSET(BANK)	(0x208 + (0x40 * BANK))
+/* Interrupt mask reg-RO */
+#define ZYNQ_GPIO_INTMASK_OFFSET(BANK)	(0x20C + (0x40 * BANK))
+/* Interrupt enable reg-WO */
+#define ZYNQ_GPIO_INTEN_OFFSET(BANK)	(0x210 + (0x40 * BANK))
+/* Interrupt disable reg-WO */
+#define ZYNQ_GPIO_INTDIS_OFFSET(BANK)	(0x214 + (0x40 * BANK))
+/* Interrupt status reg-RO */
+#define ZYNQ_GPIO_INTSTS_OFFSET(BANK)	(0x218 + (0x40 * BANK))
+/* Interrupt type reg-RW */
+#define ZYNQ_GPIO_INTTYPE_OFFSET(BANK)	(0x21C + (0x40 * BANK))
+/* Interrupt polarity reg-RW */
+#define ZYNQ_GPIO_INTPOL_OFFSET(BANK)	(0x220 + (0x40 * BANK))
+/* Interrupt on any, reg-RW */
+#define ZYNQ_GPIO_INTANY_OFFSET(BANK)	(0x224 + (0x40 * BANK))
+
+/* Disable all interrupts mask */
+#define ZYNQ_GPIO_IXR_DISABLE_ALL	0xFFFFFFFF
+
+/* Mid pin number of a bank */
+#define ZYNQ_GPIO_MID_PIN_NUM 16
+
+/* GPIO upper 16 bit mask */
+#define ZYNQ_GPIO_UPPER_MASK 0xFFFF0000
+
+/**
+ * struct zynq_gpio - gpio device private data structure
+ * @chip:	instance of the gpio_chip
+ * @base_addr:	base address of the GPIO device
+ * @clk:	clock resource for this controller
+ */
+struct zynq_gpio {
+	struct gpio_chip chip;
+	void __iomem *base_addr;
+	struct clk *clk;
+};
+
+/**
+ * zynq_gpio_get_bank_pin - Get the bank number and pin number within that bank
+ * for a given pin in the GPIO device
+ * @pin_num:	gpio pin number within the device
+ * @bank_num:	an output parameter used to return the bank number of the gpio
+ *		pin
+ * @bank_pin_num: an output parameter used to return pin number within a bank
+ *		  for the given gpio pin
+ *
+ * Returns the bank number and pin offset within the bank.
+ */
+static inline void zynq_gpio_get_bank_pin(unsigned int pin_num,
+					  unsigned int *bank_num,
+					  unsigned int *bank_pin_num)
+{
+	switch (pin_num) {
+	case ZYNQ_GPIO_BANK0_PIN_MIN ... ZYNQ_GPIO_BANK0_PIN_MAX:
+		*bank_num = 0;
+		*bank_pin_num = pin_num;
+		break;
+	case ZYNQ_GPIO_BANK1_PIN_MIN ... ZYNQ_GPIO_BANK1_PIN_MAX:
+		*bank_num = 1;
+		*bank_pin_num = pin_num - ZYNQ_GPIO_BANK1_PIN_MIN;
+		break;
+	case ZYNQ_GPIO_BANK2_PIN_MIN ... ZYNQ_GPIO_BANK2_PIN_MAX:
+		*bank_num = 2;
+		*bank_pin_num = pin_num - ZYNQ_GPIO_BANK2_PIN_MIN;
+		break;
+	case ZYNQ_GPIO_BANK3_PIN_MIN ... ZYNQ_GPIO_BANK3_PIN_MAX:
+		*bank_num = 3;
+		*bank_pin_num = pin_num - ZYNQ_GPIO_BANK3_PIN_MIN;
+		break;
+	default:
+		WARN(true, "invalid GPIO pin number: %u", pin_num);
+		*bank_num = 0;
+		*bank_pin_num = 0;
+		break;
+	}
+}
+
+/**
+ * zynq_gpio_get_value - Get the state of the specified pin of GPIO device
+ * @chip:	gpio_chip instance to be worked on
+ * @pin:	gpio pin number within the device
+ *
+ * This function reads the state of the specified pin of the GPIO device.
+ *
+ * Return: 0 if the pin is low, 1 if pin is high.
+ */
+static int zynq_gpio_get_value(struct gpio_chip *chip, unsigned int pin)
+{
+	u32 data;
+	unsigned int bank_num, bank_pin_num;
+	struct zynq_gpio *gpio = container_of(chip, struct zynq_gpio, chip);
+
+	zynq_gpio_get_bank_pin(pin, &bank_num, &bank_pin_num);
+
+	data = readl_relaxed(gpio->base_addr +
+			     ZYNQ_GPIO_DATA_RO_OFFSET(bank_num));
+
+	return (data >> bank_pin_num) & 1;
+}
+
+/**
+ * zynq_gpio_set_value - Modify the state of the pin with specified value
+ * @chip:	gpio_chip instance to be worked on
+ * @pin:	gpio pin number within the device
+ * @state:	value used to modify the state of the specified pin
+ *
+ * This function calculates the register offset (i.e to lower 16 bits or
+ * upper 16 bits) based on the given pin number and sets the state of a
+ * gpio pin to the specified value. The state is either 0 or non-zero.
+ */
+static void zynq_gpio_set_value(struct gpio_chip *chip, unsigned int pin,
+				int state)
+{
+	unsigned int reg_offset, bank_num, bank_pin_num;
+	struct zynq_gpio *gpio = container_of(chip, struct zynq_gpio, chip);
+
+	zynq_gpio_get_bank_pin(pin, &bank_num, &bank_pin_num);
+
+	if (bank_pin_num >= ZYNQ_GPIO_MID_PIN_NUM) {
+		/* only 16 data bits in bit maskable reg */
+		bank_pin_num -= ZYNQ_GPIO_MID_PIN_NUM;
+		reg_offset = ZYNQ_GPIO_DATA_MSW_OFFSET(bank_num);
+	} else {
+		reg_offset = ZYNQ_GPIO_DATA_LSW_OFFSET(bank_num);
+	}
+
+	/*
+	 * get the 32 bit value to be written to the mask/data register where
+	 * the upper 16 bits is the mask and lower 16 bits is the data
+	 */
+	state = !!state;
+	state = ~(1 << (bank_pin_num + ZYNQ_GPIO_MID_PIN_NUM)) &
+		((state << bank_pin_num) | ZYNQ_GPIO_UPPER_MASK);
+
+	writel_relaxed(state, gpio->base_addr + reg_offset);
+}
+
+/**
+ * zynq_gpio_dir_in - Set the direction of the specified GPIO pin as input
+ * @chip:	gpio_chip instance to be worked on
+ * @pin:	gpio pin number within the device
+ *
+ * This function uses the read-modify-write sequence to set the direction of
+ * the gpio pin as input.
+ *
+ * Return: 0 always
+ */
+static int zynq_gpio_dir_in(struct gpio_chip *chip, unsigned int pin)
+{
+	u32 reg;
+	unsigned int bank_num, bank_pin_num;
+	struct zynq_gpio *gpio = container_of(chip, struct zynq_gpio, chip);
+
+	zynq_gpio_get_bank_pin(pin, &bank_num, &bank_pin_num);
+
+	/* bank 0 pins 7 and 8 are special and cannot be used as inputs */
+	if (bank_num == 0 && (bank_pin_num == 7 || bank_pin_num == 8))
+		return -EINVAL;
+
+	/* clear the bit in direction mode reg to set the pin as input */
+	reg = readl_relaxed(gpio->base_addr + ZYNQ_GPIO_DIRM_OFFSET(bank_num));
+	reg &= ~BIT(bank_pin_num);
+	writel_relaxed(reg, gpio->base_addr + ZYNQ_GPIO_DIRM_OFFSET(bank_num));
+
+	return 0;
+}
+
+/**
+ * zynq_gpio_dir_out - Set the direction of the specified GPIO pin as output
+ * @chip:	gpio_chip instance to be worked on
+ * @pin:	gpio pin number within the device
+ * @state:	value to be written to specified pin
+ *
+ * This function sets the direction of specified GPIO pin as output, configures
+ * the Output Enable register for the pin and uses zynq_gpio_set to set
+ * the state of the pin to the value specified.
+ *
+ * Return: 0 always
+ */
+static int zynq_gpio_dir_out(struct gpio_chip *chip, unsigned int pin,
+			     int state)
+{
+	u32 reg;
+	unsigned int bank_num, bank_pin_num;
+	struct zynq_gpio *gpio = container_of(chip, struct zynq_gpio, chip);
+
+	zynq_gpio_get_bank_pin(pin, &bank_num, &bank_pin_num);
+
+	/* set the GPIO pin as output */
+	reg = readl_relaxed(gpio->base_addr + ZYNQ_GPIO_DIRM_OFFSET(bank_num));
+	reg |= BIT(bank_pin_num);
+	writel_relaxed(reg, gpio->base_addr + ZYNQ_GPIO_DIRM_OFFSET(bank_num));
+
+	/* configure the output enable reg for the pin */
+	reg = readl_relaxed(gpio->base_addr + ZYNQ_GPIO_OUTEN_OFFSET(bank_num));
+	reg |= BIT(bank_pin_num);
+	writel_relaxed(reg, gpio->base_addr + ZYNQ_GPIO_OUTEN_OFFSET(bank_num));
+
+	/* set the state of the pin */
+	zynq_gpio_set_value(chip, pin, state);
+	return 0;
+}
+
+/**
+ * zynq_gpio_irq_mask - Disable the interrupts for a gpio pin
+ * @irq_data:	per irq and chip data passed down to chip functions
+ *
+ * This function calculates gpio pin number from irq number and sets the
+ * bit in the Interrupt Disable register of the corresponding bank to disable
+ * interrupts for that pin.
+ */
+static void zynq_gpio_irq_mask(struct irq_data *irq_data)
+{
+	unsigned int device_pin_num, bank_num, bank_pin_num;
+	struct zynq_gpio *gpio = irq_data_get_irq_chip_data(irq_data);
+
+	device_pin_num = irq_data->hwirq;
+	zynq_gpio_get_bank_pin(device_pin_num, &bank_num, &bank_pin_num);
+	writel_relaxed(BIT(bank_pin_num),
+		       gpio->base_addr + ZYNQ_GPIO_INTDIS_OFFSET(bank_num));
+}
+
+/**
+ * zynq_gpio_irq_unmask - Enable the interrupts for a gpio pin
+ * @irq_data:	irq data containing irq number of gpio pin for the interrupt
+ *		to enable
+ *
+ * This function calculates the gpio pin number from irq number and sets the
+ * bit in the Interrupt Enable register of the corresponding bank to enable
+ * interrupts for that pin.
+ */
+static void zynq_gpio_irq_unmask(struct irq_data *irq_data)
+{
+	unsigned int device_pin_num, bank_num, bank_pin_num;
+	struct zynq_gpio *gpio = irq_data_get_irq_chip_data(irq_data);
+
+	device_pin_num = irq_data->hwirq;
+	zynq_gpio_get_bank_pin(device_pin_num, &bank_num, &bank_pin_num);
+	writel_relaxed(BIT(bank_pin_num),
+		       gpio->base_addr + ZYNQ_GPIO_INTEN_OFFSET(bank_num));
+}
+
+/**
+ * zynq_gpio_set_irq_type - Set the irq type for a gpio pin
+ * @irq_data:	irq data containing irq number of gpio pin
+ * @type:	interrupt type that is to be set for the gpio pin
+ *
+ * This function gets the gpio pin number and its bank from the gpio pin number
+ * and configures the INT_TYPE, INT_POLARITY and INT_ANY registers.
+ *
+ * Return: 0, negative error otherwise.
+ * TYPE-EDGE_RISING,  INT_TYPE - 1, INT_POLARITY - 1,  INT_ANY - 0;
+ * TYPE-EDGE_FALLING, INT_TYPE - 1, INT_POLARITY - 0,  INT_ANY - 0;
+ * TYPE-EDGE_BOTH,    INT_TYPE - 1, INT_POLARITY - NA, INT_ANY - 1;
+ * TYPE-LEVEL_HIGH,   INT_TYPE - 0, INT_POLARITY - 1,  INT_ANY - NA;
+ * TYPE-LEVEL_LOW,    INT_TYPE - 0, INT_POLARITY - 0,  INT_ANY - NA
+ */
+static int zynq_gpio_set_irq_type(struct irq_data *irq_data, unsigned int type)
+{
+	u32 int_type, int_pol, int_any;
+	unsigned int device_pin_num, bank_num, bank_pin_num;
+	struct zynq_gpio *gpio = irq_data_get_irq_chip_data(irq_data);
+
+	device_pin_num = irq_data->hwirq;
+	zynq_gpio_get_bank_pin(device_pin_num, &bank_num, &bank_pin_num);
+
+	int_type = readl_relaxed(gpio->base_addr +
+				 ZYNQ_GPIO_INTTYPE_OFFSET(bank_num));
+	int_pol = readl_relaxed(gpio->base_addr +
+				ZYNQ_GPIO_INTPOL_OFFSET(bank_num));
+	int_any = readl_relaxed(gpio->base_addr +
+				ZYNQ_GPIO_INTANY_OFFSET(bank_num));
+
+	/*
+	 * based on the type requested, configure the INT_TYPE, INT_POLARITY
+	 * and INT_ANY registers
+	 */
+	switch (type) {
+	case IRQ_TYPE_EDGE_RISING:
+		int_type |= BIT(bank_pin_num);
+		int_pol |= BIT(bank_pin_num);
+		int_any &= ~BIT(bank_pin_num);
+		break;
+	case IRQ_TYPE_EDGE_FALLING:
+		int_type |= BIT(bank_pin_num);
+		int_pol &= ~BIT(bank_pin_num);
+		int_any &= ~BIT(bank_pin_num);
+		break;
+	case IRQ_TYPE_EDGE_BOTH:
+		int_type |= BIT(bank_pin_num);
+		int_any |= BIT(bank_pin_num);
+		break;
+	case IRQ_TYPE_LEVEL_HIGH:
+		int_type &= ~BIT(bank_pin_num);
+		int_pol |= BIT(bank_pin_num);
+		break;
+	case IRQ_TYPE_LEVEL_LOW:
+		int_type &= ~BIT(bank_pin_num);
+		int_pol &= ~BIT(bank_pin_num);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	writel_relaxed(int_type,
+		       gpio->base_addr + ZYNQ_GPIO_INTTYPE_OFFSET(bank_num));
+	writel_relaxed(int_pol,
+		       gpio->base_addr + ZYNQ_GPIO_INTPOL_OFFSET(bank_num));
+	writel_relaxed(int_any,
+		       gpio->base_addr + ZYNQ_GPIO_INTANY_OFFSET(bank_num));
+	return 0;
+}
+
+static int zynq_gpio_set_wake(struct irq_data *data, unsigned int on)
+{
+	if (on)
+		zynq_gpio_irq_unmask(data);
+	else
+		zynq_gpio_irq_mask(data);
+
+	return 0;
+}
+
+/* irq chip descriptor */
+static struct irq_chip zynq_gpio_irqchip = {
+	.name		= DRIVER_NAME,
+	.irq_mask	= zynq_gpio_irq_mask,
+	.irq_unmask	= zynq_gpio_irq_unmask,
+	.irq_set_type	= zynq_gpio_set_irq_type,
+	.irq_set_wake	= zynq_gpio_set_wake,
+};
+
+/**
+ * zynq_gpio_irqhandler - IRQ handler for the gpio banks of a gpio device
+ * @irq:	irq number of the gpio bank where interrupt has occurred
+ * @desc:	irq descriptor instance of the 'irq'
+ *
+ * This function reads the Interrupt Status Register of each bank to get the
+ * gpio pin number which has triggered an interrupt. It then acks the triggered
+ * interrupt and calls the pin specific handler set by the higher layer
+ * application for that pin.
+ * Note: A bug is reported if no handler is set for the gpio pin.
+ */
+static void zynq_gpio_irqhandler(unsigned int irq, struct irq_desc *desc)
+{
+	u32 int_sts, int_enb;
+	unsigned int bank_num;
+	struct zynq_gpio *gpio = irq_get_handler_data(irq);
+	struct irq_chip *irqchip = irq_desc_get_chip(desc);
+
+	chained_irq_enter(irqchip, desc);
+
+	for (bank_num = 0; bank_num < ZYNQ_GPIO_MAX_BANK; bank_num++) {
+		int_sts = readl_relaxed(gpio->base_addr +
+					ZYNQ_GPIO_INTSTS_OFFSET(bank_num));
+		int_enb = readl_relaxed(gpio->base_addr +
+					ZYNQ_GPIO_INTMASK_OFFSET(bank_num));
+		int_sts &= ~int_enb;
+		if (int_sts) {
+			int offset;
+			unsigned long pending = int_sts;
+
+			for_each_set_bit(offset, &pending, 32) {
+				unsigned int gpio_irq =
+					irq_find_mapping(gpio->chip.irqdomain,
+							offset);
+				generic_handle_irq(gpio_irq);
+			}
+
+			/* clear IRQ in HW */
+			writel_relaxed(int_sts, gpio->base_addr +
+					ZYNQ_GPIO_INTSTS_OFFSET(bank_num));
+		}
+	}
+
+	chained_irq_exit(irqchip, desc);
+}
+
+static int __maybe_unused zynq_gpio_suspend(struct device *dev)
+{
+	if (!device_may_wakeup(dev))
+		return pm_runtime_force_suspend(dev);
+
+	return 0;
+}
+
+static int __maybe_unused zynq_gpio_resume(struct device *dev)
+{
+	if (!device_may_wakeup(dev))
+		return pm_runtime_force_resume(dev);
+
+	return 0;
+}
+
+static int __maybe_unused zynq_gpio_runtime_suspend(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct zynq_gpio *gpio = platform_get_drvdata(pdev);
+
+	clk_disable_unprepare(gpio->clk);
+
+	return 0;
+}
+
+static int __maybe_unused zynq_gpio_runtime_resume(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct zynq_gpio *gpio = platform_get_drvdata(pdev);
+
+	return clk_prepare_enable(gpio->clk);
+}
+
+static int zynq_gpio_request(struct gpio_chip *chip, unsigned offset)
+{
+	int ret;
+
+	ret = pm_runtime_get_sync(chip->dev);
+
+	/*
+	 * If the device is already active pm_runtime_get() will return 1 on
+	 * success, but gpio_request still needs to return 0.
+	 */
+	return ret < 0 ? ret : 0;
+}
+
+static void zynq_gpio_free(struct gpio_chip *chip, unsigned offset)
+{
+	pm_runtime_put(chip->dev);
+}
+
+static const struct dev_pm_ops zynq_gpio_dev_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(zynq_gpio_suspend, zynq_gpio_resume)
+	SET_PM_RUNTIME_PM_OPS(zynq_gpio_runtime_suspend,
+			zynq_gpio_runtime_resume, NULL)
+};
+
+/**
+ * zynq_gpio_probe - Initialization method for a zynq_gpio device
+ * @pdev:	platform device instance
+ *
+ * This function allocates memory resources for the gpio device and registers
+ * all the banks of the device. It will also set up interrupts for the gpio
+ * pins.
+ * Note: Interrupts are disabled for all the banks during initialization.
+ *
+ * Return: 0 on success, negative error otherwise.
+ */
+static int zynq_gpio_probe(struct platform_device *pdev)
+{
+	int ret, bank_num, irq;
+	struct zynq_gpio *gpio;
+	struct gpio_chip *chip;
+	struct resource *res;
+
+	gpio = devm_kzalloc(&pdev->dev, sizeof(*gpio), GFP_KERNEL);
+	if (!gpio)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, gpio);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	gpio->base_addr = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(gpio->base_addr))
+		return PTR_ERR(gpio->base_addr);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "invalid IRQ\n");
+		return irq;
+	}
+
+	/* configure the gpio chip */
+	chip = &gpio->chip;
+	chip->label = "zynq_gpio";
+	chip->owner = THIS_MODULE;
+	chip->dev = &pdev->dev;
+	chip->get = zynq_gpio_get_value;
+	chip->set = zynq_gpio_set_value;
+	chip->request = zynq_gpio_request;
+	chip->free = zynq_gpio_free;
+	chip->direction_input = zynq_gpio_dir_in;
+	chip->direction_output = zynq_gpio_dir_out;
+	chip->base = -1;
+	chip->ngpio = ZYNQ_GPIO_NR_GPIOS;
+
+	/* Enable GPIO clock */
+	gpio->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(gpio->clk)) {
+		dev_err(&pdev->dev, "input clock not found.\n");
+		return PTR_ERR(gpio->clk);
+	}
+	ret = clk_prepare_enable(gpio->clk);
+	if (ret) {
+		dev_err(&pdev->dev, "Unable to enable clock.\n");
+		return ret;
+	}
+
+	/* report a bug if gpio chip registration fails */
+	ret = gpiochip_add(chip);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to add gpio chip\n");
+		goto err_disable_clk;
+	}
+
+	/* disable interrupts for all banks */
+	for (bank_num = 0; bank_num < ZYNQ_GPIO_MAX_BANK; bank_num++)
+		writel_relaxed(ZYNQ_GPIO_IXR_DISABLE_ALL, gpio->base_addr +
+			       ZYNQ_GPIO_INTDIS_OFFSET(bank_num));
+
+	ret = gpiochip_irqchip_add(chip, &zynq_gpio_irqchip, 0,
+				   handle_simple_irq, IRQ_TYPE_NONE);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to add irq chip\n");
+		goto err_rm_gpiochip;
+	}
+
+	gpiochip_set_chained_irqchip(chip, &zynq_gpio_irqchip, irq,
+				     zynq_gpio_irqhandler);
+
+	pm_runtime_set_active(&pdev->dev);
+	pm_runtime_enable(&pdev->dev);
+
+	device_set_wakeup_capable(&pdev->dev, 1);
+
+	return 0;
+
+err_rm_gpiochip:
+	if (gpiochip_remove(chip))
+		dev_err(&pdev->dev, "Failed to remove gpio chip\n");
+err_disable_clk:
+	clk_disable_unprepare(gpio->clk);
+
+	return ret;
+}
+
+/**
+ * zynq_gpio_remove - Driver removal function
+ * @pdev:	platform device instance
+ *
+ * Return: 0 always
+ */
+static int zynq_gpio_remove(struct platform_device *pdev)
+{
+	int ret;
+	struct zynq_gpio *gpio = platform_get_drvdata(pdev);
+
+	pm_runtime_get_sync(&pdev->dev);
+
+	ret = gpiochip_remove(&gpio->chip);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to remove gpio chip\n");
+		return ret;
+	}
+	clk_disable_unprepare(gpio->clk);
+	device_set_wakeup_capable(&pdev->dev, 0);
+	return 0;
+}
+
+static struct of_device_id zynq_gpio_of_match[] = {
+	{ .compatible = "xlnx,zynq-gpio-1.0", },
+	{ /* end of table */ }
+};
+MODULE_DEVICE_TABLE(of, zynq_gpio_of_match);
+
+static struct platform_driver zynq_gpio_driver = {
+	.driver	= {
+		.name = DRIVER_NAME,
+		.owner = THIS_MODULE,
+		.pm = &zynq_gpio_dev_pm_ops,
+		.of_match_table = zynq_gpio_of_match,
+	},
+	.probe = zynq_gpio_probe,
+	.remove = zynq_gpio_remove,
+};
+
+/**
+ * zynq_gpio_init - Initial driver registration call
+ *
+ * Return: value from platform_driver_register
+ */
+static int __init zynq_gpio_init(void)
+{
+	return platform_driver_register(&zynq_gpio_driver);
+}
+postcore_initcall(zynq_gpio_init);
+
+MODULE_AUTHOR("Xilinx Inc.");
+MODULE_DESCRIPTION("Zynq GPIO driver");
+MODULE_LICENSE("GPL");
-- 
1.7.9.5

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