gpio.c

/*
 * linux/arch/arm/mach-at91/gpio.c
 *
 * Copyright (C) 2005 HP Labs
 *
 * 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/clk.h>
#include <linux/errno.h>
#include <linux/device.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/irqdomain.h>
#include <linux/irqchip/chained_irq.h>
#include <linux/of_address.h>

#include <mach/hardware.h>
#include <mach/at91_pio.h>

#include "generic.h"
#include "gpio.h"

#define MAX_NB_GPIO_PER_BANK	32

struct at91_gpio_chip {
	struct gpio_chip	chip;
	struct at91_gpio_chip	*next;		/* Bank sharing same clock */
	int			pioc_hwirq;	/* PIO bank interrupt identifier on AIC */
	int			pioc_virq;	/* PIO bank Linux virtual interrupt */
	int			pioc_idx;	/* PIO bank index */
	void __iomem		*regbase;	/* PIO bank virtual address */
	struct clk		*clock;		/* associated clock */
	struct irq_domain	*domain;	/* associated irq domain */
};

#define to_at91_gpio_chip(c) container_of(c, struct at91_gpio_chip, chip)

static int at91_gpiolib_request(struct gpio_chip *chip, unsigned offset);
static void at91_gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip);
static void at91_gpiolib_set(struct gpio_chip *chip, unsigned offset, int val);
static int at91_gpiolib_get(struct gpio_chip *chip, unsigned offset);
static int at91_gpiolib_direction_output(struct gpio_chip *chip,
					 unsigned offset, int val);
static int at91_gpiolib_direction_input(struct gpio_chip *chip,
					unsigned offset);
static int at91_gpiolib_to_irq(struct gpio_chip *chip, unsigned offset);

#define AT91_GPIO_CHIP(name)						\
	{								\
		.chip = {						\
			.label		  = name,			\
			.request	  = at91_gpiolib_request,	\
			.direction_input  = at91_gpiolib_direction_input, \
			.direction_output = at91_gpiolib_direction_output, \
			.get		  = at91_gpiolib_get,		\
			.set		  = at91_gpiolib_set,		\
			.dbg_show	  = at91_gpiolib_dbg_show,	\
			.to_irq		  = at91_gpiolib_to_irq,	\
			.ngpio		  = MAX_NB_GPIO_PER_BANK,	\
		},							\
	}

static struct at91_gpio_chip gpio_chip[] = {
	AT91_GPIO_CHIP("pioA"),
	AT91_GPIO_CHIP("pioB"),
	AT91_GPIO_CHIP("pioC"),
	AT91_GPIO_CHIP("pioD"),
	AT91_GPIO_CHIP("pioE"),
};

static int gpio_banks;
static unsigned long at91_gpio_caps;

/* All PIO controllers support PIO3 features */
#define AT91_GPIO_CAP_PIO3	(1 <<  0)

#define has_pio3()	(at91_gpio_caps & AT91_GPIO_CAP_PIO3)

/*--------------------------------------------------------------------------*/

static inline void __iomem *pin_to_controller(unsigned pin)
{
	pin /= MAX_NB_GPIO_PER_BANK;
	if (likely(pin < gpio_banks))
		return gpio_chip[pin].regbase;

	return NULL;
}

static inline unsigned pin_to_mask(unsigned pin)
{
	return 1 << (pin % MAX_NB_GPIO_PER_BANK);
}


static char peripheral_function(void __iomem *pio, unsigned mask)
{
	char	ret = 'X';
	u8	select;

	if (pio) {
		if (has_pio3()) {
			select = !!(__raw_readl(pio + PIO_ABCDSR1) & mask);
			select |= (!!(__raw_readl(pio + PIO_ABCDSR2) & mask) << 1);
			ret = 'A' + select;
		} else {
			ret = __raw_readl(pio + PIO_ABSR) & mask ?
							'B' : 'A';
		}
	}

	return ret;
}

/*--------------------------------------------------------------------------*/

/* Not all hardware capabilities are exposed through these calls; they
 * only encapsulate the most common features and modes.  (So if you
 * want to change signals in groups, do it directly.)
 *
 * Bootloaders will usually handle some of the pin multiplexing setup.
 * The intent is certainly that by the time Linux is fully booted, all
 * pins should have been fully initialized.  These setup calls should
 * only be used by board setup routines, or possibly in driver probe().
 *
 * For bootloaders doing all that setup, these calls could be inlined
 * as NOPs so Linux won't duplicate any setup code
 */


/*
 * mux the pin to the "GPIO" peripheral role.
 */
int __init_or_module at91_set_GPIO_periph(unsigned pin, int use_pullup)
{
	void __iomem	*pio = pin_to_controller(pin);
	unsigned	mask = pin_to_mask(pin);

	if (!pio)
		return -EINVAL;
	__raw_writel(mask, pio + PIO_IDR);
	__raw_writel(mask, pio + (use_pullup ? PIO_PUER : PIO_PUDR));
	__raw_writel(mask, pio + PIO_PER);
	return 0;
}
EXPORT_SYMBOL(at91_set_GPIO_periph);


/*
 * mux the pin to the "A" internal peripheral role.
 */
int __init_or_module at91_set_A_periph(unsigned pin, int use_pullup)
{
	void __iomem	*pio = pin_to_controller(pin);
	unsigned	mask = pin_to_mask(pin);

	if (!pio)
		return -EINVAL;

	__raw_writel(mask, pio + PIO_IDR);
	__raw_writel(mask, pio + (use_pullup ? PIO_PUER : PIO_PUDR));
	if (has_pio3()) {
		__raw_writel(__raw_readl(pio + PIO_ABCDSR1) & ~mask,
							pio + PIO_ABCDSR1);
		__raw_writel(__raw_readl(pio + PIO_ABCDSR2) & ~mask,
							pio + PIO_ABCDSR2);
	} else {
		__raw_writel(mask, pio + PIO_ASR);
	}
	__raw_writel(mask, pio + PIO_PDR);
	return 0;
}
EXPORT_SYMBOL(at91_set_A_periph);


/*
 * mux the pin to the "B" internal peripheral role.
 */
int __init_or_module at91_set_B_periph(unsigned pin, int use_pullup)
{
	void __iomem	*pio = pin_to_controller(pin);
	unsigned	mask = pin_to_mask(pin);

	if (!pio)
		return -EINVAL;

	__raw_writel(mask, pio + PIO_IDR);
	__raw_writel(mask, pio + (use_pullup ? PIO_PUER : PIO_PUDR));
	if (has_pio3()) {
		__raw_writel(__raw_readl(pio + PIO_ABCDSR1) | mask,
							pio + PIO_ABCDSR1);
		__raw_writel(__raw_readl(pio + PIO_ABCDSR2) & ~mask,
							pio + PIO_ABCDSR2);
	} else {
		__raw_writel(mask, pio + PIO_BSR);
	}
	__raw_writel(mask, pio + PIO_PDR);
	return 0;
}
EXPORT_SYMBOL(at91_set_B_periph);


/*
 * mux the pin to the "C" internal peripheral role.
 */
int __init_or_module at91_set_C_periph(unsigned pin, int use_pullup)
{
	void __iomem	*pio = pin_to_controller(pin);
	unsigned	mask = pin_to_mask(pin);

	if (!pio || !has_pio3())
		return -EINVAL;

	__raw_writel(mask, pio + PIO_IDR);
	__raw_writel(mask, pio + (use_pullup ? PIO_PUER : PIO_PUDR));
	__raw_writel(__raw_readl(pio + PIO_ABCDSR1) & ~mask, pio + PIO_ABCDSR1);
	__raw_writel(__raw_readl(pio + PIO_ABCDSR2) | mask, pio + PIO_ABCDSR2);
	__raw_writel(mask, pio + PIO_PDR);
	return 0;
}
EXPORT_SYMBOL(at91_set_C_periph);


/*
 * mux the pin to the "D" internal peripheral role.
 */
int __init_or_module at91_set_D_periph(unsigned pin, int use_pullup)
{
	void __iomem	*pio = pin_to_controller(pin);
	unsigned	mask = pin_to_mask(pin);

	if (!pio || !has_pio3())
		return -EINVAL;

	__raw_writel(mask, pio + PIO_IDR);
	__raw_writel(mask, pio + (use_pullup ? PIO_PUER : PIO_PUDR));
	__raw_writel(__raw_readl(pio + PIO_ABCDSR1) | mask, pio + PIO_ABCDSR1);
	__raw_writel(__raw_readl(pio + PIO_ABCDSR2) | mask, pio + PIO_ABCDSR2);
	__raw_writel(mask, pio + PIO_PDR);
	return 0;
}
EXPORT_SYMBOL(at91_set_D_periph);


/*
 * mux the pin to the gpio controller (instead of "A", "B", "C"
 * or "D" peripheral), and configure it for an input.
 */
int __init_or_module at91_set_gpio_input(unsigned pin, int use_pullup)
{
	void __iomem	*pio = pin_to_controller(pin);
	unsigned	mask = pin_to_mask(pin);

	if (!pio)
		return -EINVAL;

	__raw_writel(mask, pio + PIO_IDR);
	__raw_writel(mask, pio + (use_pullup ? PIO_PUER : PIO_PUDR));
	__raw_writel(mask, pio + PIO_ODR);
	__raw_writel(mask, pio + PIO_PER);
	return 0;
}
EXPORT_SYMBOL(at91_set_gpio_input);


/*
 * mux the pin to the gpio controller (instead of "A", "B", "C"
 * or "D" peripheral), and configure it for an output.
 */
int __init_or_module at91_set_gpio_output(unsigned pin, int value)
{
	void __iomem	*pio = pin_to_controller(pin);
	unsigned	mask = pin_to_mask(pin);

	if (!pio)
		return -EINVAL;

	__raw_writel(mask, pio + PIO_IDR);
	__raw_writel(mask, pio + PIO_PUDR);
	__raw_writel(mask, pio + (value ? PIO_SODR : PIO_CODR));
	__raw_writel(mask, pio + PIO_OER);
	__raw_writel(mask, pio + PIO_PER);
	return 0;
}
EXPORT_SYMBOL(at91_set_gpio_output);


/*
 * enable/disable the glitch filter; mostly used with IRQ handling.
 */
int __init_or_module at91_set_deglitch(unsigned pin, int is_on)
{
	void __iomem	*pio = pin_to_controller(pin);
	unsigned	mask = pin_to_mask(pin);

	if (!pio)
		return -EINVAL;

	if (has_pio3() && is_on)
		__raw_writel(mask, pio + PIO_IFSCDR);
	__raw_writel(mask, pio + (is_on ? PIO_IFER : PIO_IFDR));
	return 0;
}
EXPORT_SYMBOL(at91_set_deglitch);

/*
 * enable/disable the debounce filter;
 */
int __init_or_module at91_set_debounce(unsigned pin, int is_on, int div)
{
	void __iomem	*pio = pin_to_controller(pin);
	unsigned	mask = pin_to_mask(pin);

	if (!pio || !has_pio3())
		return -EINVAL;

	if (is_on) {
		__raw_writel(mask, pio + PIO_IFSCER);
		__raw_writel(div & PIO_SCDR_DIV, pio + PIO_SCDR);
		__raw_writel(mask, pio + PIO_IFER);
	} else {
		__raw_writel(mask, pio + PIO_IFDR);
	}
	return 0;
}
EXPORT_SYMBOL(at91_set_debounce);

/*
 * enable/disable the multi-driver; This is only valid for output and
 * allows the output pin to run as an open collector output.
 */
int __init_or_module at91_set_multi_drive(unsigned pin, int is_on)
{
	void __iomem	*pio = pin_to_controller(pin);
	unsigned	mask = pin_to_mask(pin);

	if (!pio)
		return -EINVAL;

	__raw_writel(mask, pio + (is_on ? PIO_MDER : PIO_MDDR));
	return 0;
}
EXPORT_SYMBOL(at91_set_multi_drive);

/*
 * enable/disable the pull-down.
 * If pull-up already enabled while calling the function, we disable it.
 */
int __init_or_module at91_set_pulldown(unsigned pin, int is_on)
{
	void __iomem	*pio = pin_to_controller(pin);
	unsigned	mask = pin_to_mask(pin);

	if (!pio || !has_pio3())
		return -EINVAL;

	/* Disable pull-up anyway */
	__raw_writel(mask, pio + PIO_PUDR);
	__raw_writel(mask, pio + (is_on ? PIO_PPDER : PIO_PPDDR));
	return 0;
}
EXPORT_SYMBOL(at91_set_pulldown);

/*
 * disable Schmitt trigger
 */
int __init_or_module at91_disable_schmitt_trig(unsigned pin)
{
	void __iomem	*pio = pin_to_controller(pin);
	unsigned	mask = pin_to_mask(pin);

	if (!pio || !has_pio3())
		return -EINVAL;

	__raw_writel(__raw_readl(pio + PIO_SCHMITT) | mask, pio + PIO_SCHMITT);
	return 0;
}
EXPORT_SYMBOL(at91_disable_schmitt_trig);

/*
 * assuming the pin is muxed as a gpio output, set its value.
 */
int at91_set_gpio_value(unsigned pin, int value)
{
	void __iomem	*pio = pin_to_controller(pin);
	unsigned	mask = pin_to_mask(pin);

	if (!pio)
		return -EINVAL;
	__raw_writel(mask, pio + (value ? PIO_SODR : PIO_CODR));
	return 0;
}
EXPORT_SYMBOL(at91_set_gpio_value);


/*
 * read the pin's value (works even if it's not muxed as a gpio).
 */
int at91_get_gpio_value(unsigned pin)
{
	void __iomem	*pio = pin_to_controller(pin);
	unsigned	mask = pin_to_mask(pin);
	u32		pdsr;

	if (!pio)
		return -EINVAL;
	pdsr = __raw_readl(pio + PIO_PDSR);
	return (pdsr & mask) != 0;
}
EXPORT_SYMBOL(at91_get_gpio_value);

/*--------------------------------------------------------------------------*/

#ifdef CONFIG_PM

static u32 wakeups[MAX_GPIO_BANKS];
static u32 backups[MAX_GPIO_BANKS];

static int gpio_irq_set_wake(struct irq_data *d, unsigned state)
{
	struct at91_gpio_chip *at91_gpio = irq_data_get_irq_chip_data(d);
	unsigned	mask = 1 << d->hwirq;
	unsigned	bank = at91_gpio->pioc_idx;

	if (unlikely(bank >= MAX_GPIO_BANKS))
		return -EINVAL;

	if (state)
		wakeups[bank] |= mask;
	else
		wakeups[bank] &= ~mask;

	irq_set_irq_wake(at91_gpio->pioc_virq, state);

	return 0;
}

void at91_gpio_suspend(void)
{
	int i;

	for (i = 0; i < gpio_banks; i++) {
		void __iomem	*pio = gpio_chip[i].regbase;

		backups[i] = __raw_readl(pio + PIO_IMR);
		__raw_writel(backups[i], pio + PIO_IDR);
		__raw_writel(wakeups[i], pio + PIO_IER);

		if (!wakeups[i]) {
			clk_unprepare(gpio_chip[i].clock);
			clk_disable(gpio_chip[i].clock);
		} else {
#ifdef CONFIG_PM_DEBUG
			printk(KERN_DEBUG "GPIO-%c may wake for %08x\n", 'A'+i, wakeups[i]);
#endif
		}
	}
}

void at91_gpio_resume(void)
{
	int i;

	for (i = 0; i < gpio_banks; i++) {
		void __iomem	*pio = gpio_chip[i].regbase;

		if (!wakeups[i]) {
			if (clk_prepare(gpio_chip[i].clock) == 0)
				clk_enable(gpio_chip[i].clock);
		}

		__raw_writel(wakeups[i], pio + PIO_IDR);
		__raw_writel(backups[i], pio + PIO_IER);
	}
}

#else
#define gpio_irq_set_wake	NULL
#endif


/* Several AIC controller irqs are dispatched through this GPIO handler.
 * To use any AT91_PIN_* as an externally triggered IRQ, first call
 * at91_set_gpio_input() then maybe enable its glitch filter.
 * Then just request_irq() with the pin ID; it works like any ARM IRQ
 * handler.
 * First implementation always triggers on rising and falling edges
 * whereas the newer PIO3 can be additionally configured to trigger on
 * level, edge with any polarity.
 *
 * Alternatively, certain pins may be used directly as IRQ0..IRQ6 after
 * configuring them with at91_set_a_periph() or at91_set_b_periph().
 * IRQ0..IRQ6 should be configurable, e.g. level vs edge triggering.
 */

static void gpio_irq_mask(struct irq_data *d)
{
	struct at91_gpio_chip *at91_gpio = irq_data_get_irq_chip_data(d);
	void __iomem	*pio = at91_gpio->regbase;
	unsigned	mask = 1 << d->hwirq;

	if (pio)
		__raw_writel(mask, pio + PIO_IDR);
}

static void gpio_irq_unmask(struct irq_data *d)
{
	struct at91_gpio_chip *at91_gpio = irq_data_get_irq_chip_data(d);
	void __iomem	*pio = at91_gpio->regbase;
	unsigned	mask = 1 << d->hwirq;

	if (pio)
		__raw_writel(mask, pio + PIO_IER);
}

static int gpio_irq_type(struct irq_data *d, unsigned type)
{
	switch (type) {
	case IRQ_TYPE_NONE:
	case IRQ_TYPE_EDGE_BOTH:
		return 0;
	default:
		return -EINVAL;
	}
}

/* Alternate irq type for PIO3 support */
static int alt_gpio_irq_type(struct irq_data *d, unsigned type)
{
	struct at91_gpio_chip *at91_gpio = irq_data_get_irq_chip_data(d);
	void __iomem	*pio = at91_gpio->regbase;
	unsigned	mask = 1 << d->hwirq;

	switch (type) {
	case IRQ_TYPE_EDGE_RISING:
		__raw_writel(mask, pio + PIO_ESR);
		__raw_writel(mask, pio + PIO_REHLSR);
		break;
	case IRQ_TYPE_EDGE_FALLING:
		__raw_writel(mask, pio + PIO_ESR);
		__raw_writel(mask, pio + PIO_FELLSR);
		break;
	case IRQ_TYPE_LEVEL_LOW:
		__raw_writel(mask, pio + PIO_LSR);
		__raw_writel(mask, pio + PIO_FELLSR);
		break;
	case IRQ_TYPE_LEVEL_HIGH:
		__raw_writel(mask, pio + PIO_LSR);
		__raw_writel(mask, pio + PIO_REHLSR);
		break;
	case IRQ_TYPE_EDGE_BOTH:
		/*
		 * disable additional interrupt modes:
		 * fall back to default behavior
		 */
		__raw_writel(mask, pio + PIO_AIMDR);
		return 0;
	case IRQ_TYPE_NONE:
	default:
		pr_warn("AT91: No type for irq %d\n", gpio_to_irq(d->irq));
		return -EINVAL;
	}

	/* enable additional interrupt modes */
	__raw_writel(mask, pio + PIO_AIMER);

	return 0;
}

static struct irq_chip gpio_irqchip = {
	.name		= "GPIO",
	.irq_disable	= gpio_irq_mask,
	.irq_mask	= gpio_irq_mask,
	.irq_unmask	= gpio_irq_unmask,
	/* .irq_set_type is set dynamically */
	.irq_set_wake	= gpio_irq_set_wake,
};

static void gpio_irq_handler(unsigned irq, struct irq_desc *desc)
{
	struct irq_chip *chip = irq_desc_get_chip(desc);
	struct irq_data *idata = irq_desc_get_irq_data(desc);
	struct at91_gpio_chip *at91_gpio = irq_data_get_irq_chip_data(idata);
	void __iomem	*pio = at91_gpio->regbase;
	unsigned long	isr;
	int		n;

	chained_irq_enter(chip, desc);
	for (;;) {
		/* Reading ISR acks pending (edge triggered) GPIO interrupts.
		 * When there none are pending, we're finished unless we need
		 * to process multiple banks (like ID_PIOCDE on sam9263).
		 */
		isr = __raw_readl(pio + PIO_ISR) & __raw_readl(pio + PIO_IMR);
		if (!isr) {
			if (!at91_gpio->next)
				break;
			at91_gpio = at91_gpio->next;
			pio = at91_gpio->regbase;
			continue;
		}

		n = find_first_bit(&isr, BITS_PER_LONG);
		while (n < BITS_PER_LONG) {
			generic_handle_irq(irq_find_mapping(at91_gpio->domain, n));
			n = find_next_bit(&isr, BITS_PER_LONG, n + 1);
		}
	}
	chained_irq_exit(chip, desc);
	/* now it may re-trigger */
}

/*--------------------------------------------------------------------------*/

#ifdef CONFIG_DEBUG_FS

static void gpio_printf(struct seq_file *s, void __iomem *pio, unsigned mask)
{
	char	*trigger = NULL;
	char	*polarity = NULL;

	if (__raw_readl(pio + PIO_IMR) & mask) {
		if (!has_pio3() || !(__raw_readl(pio + PIO_AIMMR) & mask )) {
			trigger = "edge";
			polarity = "both";
		} else {
			if (__raw_readl(pio + PIO_ELSR) & mask) {
				trigger = "level";
				polarity = __raw_readl(pio + PIO_FRLHSR) & mask ?
					"high" : "low";
			} else {
				trigger = "edge";
				polarity = __raw_readl(pio + PIO_FRLHSR) & mask ?
						"rising" : "falling";
			}
		}
		seq_printf(s, "IRQ:%s-%s\t", trigger, polarity);
	} else {
		seq_printf(s, "GPIO:%s\t\t",
				__raw_readl(pio + PIO_PDSR) & mask ? "1" : "0");
	}
}

static int at91_gpio_show(struct seq_file *s, void *unused)
{
	int bank, j;

	/* print heading */
	seq_printf(s, "Pin\t");
	for (bank = 0; bank < gpio_banks; bank++) {
		seq_printf(s, "PIO%c\t\t", 'A' + bank);
	};
	seq_printf(s, "\n\n");

	/* print pin status */
	for (j = 0; j < 32; j++) {
		seq_printf(s, "%i:\t", j);

		for (bank = 0; bank < gpio_banks; bank++) {
			unsigned	pin  = (32 * bank) + j;
			void __iomem	*pio = pin_to_controller(pin);
			unsigned	mask = pin_to_mask(pin);

			if (__raw_readl(pio + PIO_PSR) & mask)
				gpio_printf(s, pio, mask);
			else
				seq_printf(s, "%c\t\t",
						peripheral_function(pio, mask));
		}

		seq_printf(s, "\n");
	}

	return 0;
}

static int at91_gpio_open(struct inode *inode, struct file *file)
{
	return single_open(file, at91_gpio_show, NULL);
}

static const struct file_operations at91_gpio_operations = {
	.open		= at91_gpio_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
};

static int __init at91_gpio_debugfs_init(void)
{
	/* /sys/kernel/debug/at91_gpio */
	(void) debugfs_create_file("at91_gpio", S_IFREG | S_IRUGO, NULL, NULL, &at91_gpio_operations);
	return 0;
}
postcore_initcall(at91_gpio_debugfs_init);

#endif

/*--------------------------------------------------------------------------*/

/*
 * This lock class tells lockdep that GPIO irqs are in a different
 * category than their parents, so it won't report false recursion.
 */
static struct lock_class_key gpio_lock_class;

/*
 * irqdomain initialization: pile up irqdomains on top of AIC range
 */
static void __init at91_gpio_irqdomain(struct at91_gpio_chip *at91_gpio)
{
	int irq_base;

	irq_base = irq_alloc_descs(-1, 0, at91_gpio->chip.ngpio, 0);
	if (irq_base < 0)
		panic("at91_gpio.%d: error %d: couldn't allocate IRQ numbers.\n",
			at91_gpio->pioc_idx, irq_base);
	at91_gpio->domain = irq_domain_add_legacy(NULL, at91_gpio->chip.ngpio,
						  irq_base, 0,
						  &irq_domain_simple_ops, NULL);
	if (!at91_gpio->domain)
		panic("at91_gpio.%d: couldn't allocate irq domain.\n",
			at91_gpio->pioc_idx);
}

/*
 * Called from the processor-specific init to enable GPIO interrupt support.
 */
void __init at91_gpio_irq_setup(void)
{
	unsigned		pioc;
	int			gpio_irqnbr = 0;
	struct at91_gpio_chip	*this, *prev;

	/* Setup proper .irq_set_type function */
	if (has_pio3())
		gpio_irqchip.irq_set_type = alt_gpio_irq_type;
	else
		gpio_irqchip.irq_set_type = gpio_irq_type;

	for (pioc = 0, this = gpio_chip, prev = NULL;
			pioc++ < gpio_banks;
			prev = this, this++) {
		int offset;

		__raw_writel(~0, this->regbase + PIO_IDR);

		/* setup irq domain for this GPIO controller */
		at91_gpio_irqdomain(this);

		for (offset = 0; offset < this->chip.ngpio; offset++) {
			unsigned int virq = irq_find_mapping(this->domain, offset);
			irq_set_lockdep_class(virq, &gpio_lock_class);

			/*
			 * Can use the "simple" and not "edge" handler since it's
			 * shorter, and the AIC handles interrupts sanely.
			 */
			irq_set_chip_and_handler(virq, &gpio_irqchip,
						 handle_simple_irq);
			set_irq_flags(virq, IRQF_VALID);
			irq_set_chip_data(virq, this);

			gpio_irqnbr++;
		}

		/* The toplevel handler handles one bank of GPIOs, except
		 * on some SoC it can handles up to three...
		 * We only set up the handler for the first of the list.
		 */
		if (prev && prev->next == this)
			continue;

		this->pioc_virq = irq_create_mapping(NULL, this->pioc_hwirq);
		irq_set_chip_data(this->pioc_virq, this);
		irq_set_chained_handler(this->pioc_virq, gpio_irq_handler);
	}
	pr_info("AT91: %d gpio irqs in %d banks\n", gpio_irqnbr, gpio_banks);
}

/* gpiolib support */
static int at91_gpiolib_request(struct gpio_chip *chip, unsigned offset)
{
	struct at91_gpio_chip *at91_gpio = to_at91_gpio_chip(chip);
	void __iomem *pio = at91_gpio->regbase;
	unsigned mask = 1 << offset;

	__raw_writel(mask, pio + PIO_PER);
	return 0;
}

static int at91_gpiolib_direction_input(struct gpio_chip *chip,
					unsigned offset)
{
	struct at91_gpio_chip *at91_gpio = to_at91_gpio_chip(chip);
	void __iomem *pio = at91_gpio->regbase;
	unsigned mask = 1 << offset;

	__raw_writel(mask, pio + PIO_ODR);
	return 0;
}

static int at91_gpiolib_direction_output(struct gpio_chip *chip,
					 unsigned offset, int val)
{
	struct at91_gpio_chip *at91_gpio = to_at91_gpio_chip(chip);
	void __iomem *pio = at91_gpio->regbase;
	unsigned mask = 1 << offset;

	__raw_writel(mask, pio + (val ? PIO_SODR : PIO_CODR));
	__raw_writel(mask, pio + PIO_OER);
	return 0;
}

static int at91_gpiolib_get(struct gpio_chip *chip, unsigned offset)
{
	struct at91_gpio_chip *at91_gpio = to_at91_gpio_chip(chip);
	void __iomem *pio = at91_gpio->regbase;
	unsigned mask = 1 << offset;
	u32 pdsr;

	pdsr = __raw_readl(pio + PIO_PDSR);
	return (pdsr & mask) != 0;
}

static void at91_gpiolib_set(struct gpio_chip *chip, unsigned offset, int val)
{
	struct at91_gpio_chip *at91_gpio = to_at91_gpio_chip(chip);
	void __iomem *pio = at91_gpio->regbase;
	unsigned mask = 1 << offset;

	__raw_writel(mask, pio + (val ? PIO_SODR : PIO_CODR));
}

static void at91_gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
{
	int i;

	for (i = 0; i < chip->ngpio; i++) {
		unsigned pin = chip->base + i;
		void __iomem *pio = pin_to_controller(pin);
		unsigned mask = pin_to_mask(pin);
		const char *gpio_label;

		gpio_label = gpiochip_is_requested(chip, i);
		if (gpio_label) {
			seq_printf(s, "[%s] GPIO%s%d: ",
				   gpio_label, chip->label, i);
			if (__raw_readl(pio + PIO_PSR) & mask)
				seq_printf(s, "[gpio] %s\n",
					   at91_get_gpio_value(pin) ?
					   "set" : "clear");
			else
				seq_printf(s, "[periph %c]\n",
					   peripheral_function(pio, mask));
		}
	}
}

static int at91_gpiolib_to_irq(struct gpio_chip *chip, unsigned offset)
{
	struct at91_gpio_chip *at91_gpio = to_at91_gpio_chip(chip);
	int virq;

	if (offset < chip->ngpio)
		virq = irq_create_mapping(at91_gpio->domain, offset);
	else
		virq = -ENXIO;

	dev_dbg(chip->dev, "%s: request IRQ for GPIO %d, return %d\n",
				chip->label, offset + chip->base, virq);
	return virq;
}

static int __init at91_gpio_setup_clk(int idx)
{
	struct at91_gpio_chip *at91_gpio = &gpio_chip[idx];

	/* retreive PIO controller's clock */
	at91_gpio->clock = clk_get_sys(NULL, at91_gpio->chip.label);
	if (IS_ERR(at91_gpio->clock)) {
		pr_err("at91_gpio.%d, failed to get clock, ignoring.\n", idx);
		goto err;
	}

	if (clk_prepare(at91_gpio->clock))
		goto clk_prep_err;

	/* enable PIO controller's clock */
	if (clk_enable(at91_gpio->clock)) {
		pr_err("at91_gpio.%d, failed to enable clock, ignoring.\n", idx);
		goto clk_err;
	}

	return 0;

clk_err:
	clk_unprepare(at91_gpio->clock);
clk_prep_err:
	clk_put(at91_gpio->clock);
err:
	return -EINVAL;
}

static void __init at91_gpio_init_one(int idx, u32 regbase, int pioc_hwirq)
{
	struct at91_gpio_chip *at91_gpio = &gpio_chip[idx];

	at91_gpio->chip.base = idx * MAX_NB_GPIO_PER_BANK;
	at91_gpio->pioc_hwirq = pioc_hwirq;
	at91_gpio->pioc_idx = idx;

	at91_gpio->regbase = ioremap(regbase, 512);
	if (!at91_gpio->regbase) {
		pr_err("at91_gpio.%d, failed to map registers, ignoring.\n", idx);
		return;
	}

	if (at91_gpio_setup_clk(idx))
		goto ioremap_err;

	gpio_banks = max(gpio_banks, idx + 1);
	return;

ioremap_err:
	iounmap(at91_gpio->regbase);
}

/*
 * Called from the processor-specific init to enable GPIO pin support.
 */
void __init at91_gpio_init(struct at91_gpio_bank *data, int nr_banks)
{
	unsigned i;
	struct at91_gpio_chip *at91_gpio, *last = NULL;

	BUG_ON(nr_banks > MAX_GPIO_BANKS);

	if (of_have_populated_dt())
		return;

	for (i = 0; i < nr_banks; i++)
		at91_gpio_init_one(i, data[i].regbase, data[i].id);

	for (i = 0; i < gpio_banks; i++) {
		at91_gpio = &gpio_chip[i];

		/*
		 * GPIO controller are grouped on some SoC:
		 * PIOC, PIOD and PIOE can share the same IRQ line
		 */
		if (last && last->pioc_hwirq == at91_gpio->pioc_hwirq)
			last->next = at91_gpio;
		last = at91_gpio;

		gpiochip_add(&at91_gpio->chip);
	}
}