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/*
* Xilinx gpio driver
*
* Copyright 2008 Xilinx, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/of_platform.h>
#include <linux/of_gpio.h>
#include <linux/io.h>
#include <linux/gpio.h>
#include <linux/slab.h>
/* Register Offset Definitions */
#define XGPIO_DATA_OFFSET (0x0) /* Data register */
#define XGPIO_TRI_OFFSET (0x4) /* I/O direction register */
struct xgpio_instance {
struct of_mm_gpio_chip mmchip;
u32 gpio_state; /* GPIO state shadow register */
u32 gpio_dir; /* GPIO direction shadow register */
spinlock_t gpio_lock; /* Lock used for synchronization */
};
/**
* xgpio_get - Read the specified signal of the GPIO device.
* @gc: Pointer to gpio_chip device structure.
* @gpio: GPIO signal number.
*
* This function reads the specified signal of the GPIO device. It returns 0 if
* the signal clear, 1 if signal is set or negative value on error.
*/
static int xgpio_get(struct gpio_chip *gc, unsigned int gpio)
{
struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
return (in_be32(mm_gc->regs + XGPIO_DATA_OFFSET) >> gpio) & 1;
}
/**
* xgpio_set - Write the specified signal of the GPIO device.
* @gc: Pointer to gpio_chip device structure.
* @gpio: GPIO signal number.
* @val: Value to be written to specified signal.
*
* This function writes the specified value in to the specified signal of the
* GPIO device.
*/
static void xgpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
{
unsigned long flags;
struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
struct xgpio_instance *chip =
container_of(mm_gc, struct xgpio_instance, mmchip);
spin_lock_irqsave(&chip->gpio_lock, flags);
/* Write to GPIO signal and set its direction to output */
if (val)
chip->gpio_state |= 1 << gpio;
else
chip->gpio_state &= ~(1 << gpio);
out_be32(mm_gc->regs + XGPIO_DATA_OFFSET, chip->gpio_state);
spin_unlock_irqrestore(&chip->gpio_lock, flags);
}
/**
* xgpio_dir_in - Set the direction of the specified GPIO signal as input.
* @gc: Pointer to gpio_chip device structure.
* @gpio: GPIO signal number.
*
* This function sets the direction of specified GPIO signal as input.
* It returns 0 if direction of GPIO signals is set as input otherwise it
* returns negative error value.
*/
static int xgpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
{
unsigned long flags;
struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
struct xgpio_instance *chip =
container_of(mm_gc, struct xgpio_instance, mmchip);
spin_lock_irqsave(&chip->gpio_lock, flags);
/* Set the GPIO bit in shadow register and set direction as input */
chip->gpio_dir |= (1 << gpio);
out_be32(mm_gc->regs + XGPIO_TRI_OFFSET, chip->gpio_dir);
spin_unlock_irqrestore(&chip->gpio_lock, flags);
return 0;
}
/**
* xgpio_dir_out - Set the direction of the specified GPIO signal as output.
* @gc: Pointer to gpio_chip device structure.
* @gpio: GPIO signal number.
* @val: Value to be written to specified signal.
*
* This function sets the direction of specified GPIO signal as output. If all
* GPIO signals of GPIO chip is configured as input then it returns
* error otherwise it returns 0.
*/
static int xgpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
{
unsigned long flags;
struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
struct xgpio_instance *chip =
container_of(mm_gc, struct xgpio_instance, mmchip);
spin_lock_irqsave(&chip->gpio_lock, flags);
/* Write state of GPIO signal */
if (val)
chip->gpio_state |= 1 << gpio;
else
chip->gpio_state &= ~(1 << gpio);
out_be32(mm_gc->regs + XGPIO_DATA_OFFSET, chip->gpio_state);
/* Clear the GPIO bit in shadow register and set direction as output */
chip->gpio_dir &= (~(1 << gpio));
out_be32(mm_gc->regs + XGPIO_TRI_OFFSET, chip->gpio_dir);
spin_unlock_irqrestore(&chip->gpio_lock, flags);
return 0;
}
/**
* xgpio_save_regs - Set initial values of GPIO pins
* @mm_gc: pointer to memory mapped GPIO chip structure
*/
static void xgpio_save_regs(struct of_mm_gpio_chip *mm_gc)
{
struct xgpio_instance *chip =
container_of(mm_gc, struct xgpio_instance, mmchip);
out_be32(mm_gc->regs + XGPIO_DATA_OFFSET, chip->gpio_state);
out_be32(mm_gc->regs + XGPIO_TRI_OFFSET, chip->gpio_dir);
}
/**
* xgpio_of_probe - Probe method for the GPIO device.
* @np: pointer to device tree node
*
* This function probes the GPIO device in the device tree. It initializes the
* driver data structure. It returns 0, if the driver is bound to the GPIO
* device, or a negative value if there is an error.
*/
static int xgpio_of_probe(struct device_node *np)
{
struct xgpio_instance *chip;
int status = 0;
const u32 *tree_info;
chip = kzalloc(sizeof(*chip), GFP_KERNEL);
if (!chip)
return -ENOMEM;
/* Update GPIO state shadow register with default value */
tree_info = of_get_property(np, "xlnx,dout-default", NULL);
if (tree_info)
chip->gpio_state = be32_to_cpup(tree_info);
/* Update GPIO direction shadow register with default value */
chip->gpio_dir = 0xFFFFFFFF; /* By default, all pins are inputs */
tree_info = of_get_property(np, "xlnx,tri-default", NULL);
if (tree_info)
chip->gpio_dir = be32_to_cpup(tree_info);
/* Check device node and parent device node for device width */
chip->mmchip.gc.ngpio = 32; /* By default assume full GPIO controller */
tree_info = of_get_property(np, "xlnx,gpio-width", NULL);
if (!tree_info)
tree_info = of_get_property(np->parent,
"xlnx,gpio-width", NULL);
if (tree_info)
chip->mmchip.gc.ngpio = be32_to_cpup(tree_info);
spin_lock_init(&chip->gpio_lock);
chip->mmchip.gc.direction_input = xgpio_dir_in;
chip->mmchip.gc.direction_output = xgpio_dir_out;
chip->mmchip.gc.get = xgpio_get;
chip->mmchip.gc.set = xgpio_set;
chip->mmchip.save_regs = xgpio_save_regs;
/* Call the OF gpio helper to setup and register the GPIO device */
status = of_mm_gpiochip_add(np, &chip->mmchip);
if (status) {
kfree(chip);
pr_err("%s: error in probe function with status %d\n",
np->full_name, status);
return status;
}
return 0;
}
static struct of_device_id xgpio_of_match[] = {
{ .compatible = "xlnx,xps-gpio-1.00.a", },
{ /* end of list */ },
};
static int __init xgpio_init(void)
{
struct device_node *np;
for_each_matching_node(np, xgpio_of_match)
xgpio_of_probe(np);
return 0;
}
/* Make sure we get initialized before anyone else tries to use us */
subsys_initcall(xgpio_init);
/* No exit call at the moment as we cannot unregister of GPIO chips */
MODULE_AUTHOR("Xilinx, Inc.");
MODULE_DESCRIPTION("Xilinx GPIO driver");
MODULE_LICENSE("GPL");
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