diff options
Diffstat (limited to 'drivers/gpio/xilinx_gpio.c')
| -rw-r--r-- | drivers/gpio/xilinx_gpio.c | 235 |
1 files changed, 235 insertions, 0 deletions
diff --git a/drivers/gpio/xilinx_gpio.c b/drivers/gpio/xilinx_gpio.c new file mode 100644 index 0000000..3c1177a --- /dev/null +++ b/drivers/gpio/xilinx_gpio.c @@ -0,0 +1,235 @@ +/* + * 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/of_device.h> +#include <linux/of_platform.h> +#include <linux/of_gpio.h> +#include <linux/io.h> +#include <linux/gpio.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 __devinit xgpio_of_probe(struct device_node *np) +{ + struct xgpio_instance *chip; + struct of_gpio_chip *ofchip; + int status = 0; + const u32 *tree_info; + + chip = kzalloc(sizeof(*chip), GFP_KERNEL); + if (!chip) + return -ENOMEM; + ofchip = &chip->mmchip.of_gc; + + /* Update GPIO state shadow register with default value */ + tree_info = of_get_property(np, "xlnx,dout-default", NULL); + if (tree_info) + chip->gpio_state = *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 = *tree_info; + + /* Check device node and parent device node for device width */ + ofchip->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) + ofchip->gc.ngpio = *tree_info; + + spin_lock_init(&chip->gpio_lock); + + ofchip->gpio_cells = 2; + ofchip->gc.direction_input = xgpio_dir_in; + ofchip->gc.direction_output = xgpio_dir_out; + ofchip->gc.get = xgpio_get; + ofchip->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; + } + pr_info("XGpio: %s: registered\n", np->full_name); + return 0; +} + +static struct of_device_id xgpio_of_match[] __devinitdata = { + { .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"); |