1/* 2 * Xilinx gpio driver 3 * 4 * Copyright 2008 Xilinx, Inc. 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 8 * as published by the Free Software Foundation. 9 * 10 * You should have received a copy of the GNU General Public License 11 * along with this program; if not, write to the Free Software 12 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 13 */ 14 15#include <linux/init.h> 16#include <linux/errno.h> 17#include <linux/of_device.h> 18#include <linux/of_platform.h> 19#include <linux/of_gpio.h> 20#include <linux/io.h> 21#include <linux/gpio.h> 22#include <linux/slab.h> 23 24/* Register Offset Definitions */ 25#define XGPIO_DATA_OFFSET (0x0) /* Data register */ 26#define XGPIO_TRI_OFFSET (0x4) /* I/O direction register */ 27 28struct xgpio_instance { 29 struct of_mm_gpio_chip mmchip; 30 u32 gpio_state; /* GPIO state shadow register */ 31 u32 gpio_dir; /* GPIO direction shadow register */ 32 spinlock_t gpio_lock; /* Lock used for synchronization */ 33}; 34 35/** 36 * xgpio_get - Read the specified signal of the GPIO device. 37 * @gc: Pointer to gpio_chip device structure. 38 * @gpio: GPIO signal number. 39 * 40 * This function reads the specified signal of the GPIO device. It returns 0 if 41 * the signal clear, 1 if signal is set or negative value on error. 42 */ 43static int xgpio_get(struct gpio_chip *gc, unsigned int gpio) 44{ 45 struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc); 46 47 return (in_be32(mm_gc->regs + XGPIO_DATA_OFFSET) >> gpio) & 1; 48} 49 50/** 51 * xgpio_set - Write the specified signal of the GPIO device. 52 * @gc: Pointer to gpio_chip device structure. 53 * @gpio: GPIO signal number. 54 * @val: Value to be written to specified signal. 55 * 56 * This function writes the specified value in to the specified signal of the 57 * GPIO device. 58 */ 59static void xgpio_set(struct gpio_chip *gc, unsigned int gpio, int val) 60{ 61 unsigned long flags; 62 struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc); 63 struct xgpio_instance *chip = 64 container_of(mm_gc, struct xgpio_instance, mmchip); 65 66 spin_lock_irqsave(&chip->gpio_lock, flags); 67 68 /* Write to GPIO signal and set its direction to output */ 69 if (val) 70 chip->gpio_state |= 1 << gpio; 71 else 72 chip->gpio_state &= ~(1 << gpio); 73 out_be32(mm_gc->regs + XGPIO_DATA_OFFSET, chip->gpio_state); 74 75 spin_unlock_irqrestore(&chip->gpio_lock, flags); 76} 77 78/** 79 * xgpio_dir_in - Set the direction of the specified GPIO signal as input. 80 * @gc: Pointer to gpio_chip device structure. 81 * @gpio: GPIO signal number. 82 * 83 * This function sets the direction of specified GPIO signal as input. 84 * It returns 0 if direction of GPIO signals is set as input otherwise it 85 * returns negative error value. 86 */ 87static int xgpio_dir_in(struct gpio_chip *gc, unsigned int gpio) 88{ 89 unsigned long flags; 90 struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc); 91 struct xgpio_instance *chip = 92 container_of(mm_gc, struct xgpio_instance, mmchip); 93 94 spin_lock_irqsave(&chip->gpio_lock, flags); 95 96 /* Set the GPIO bit in shadow register and set direction as input */ 97 chip->gpio_dir |= (1 << gpio); 98 out_be32(mm_gc->regs + XGPIO_TRI_OFFSET, chip->gpio_dir); 99 100 spin_unlock_irqrestore(&chip->gpio_lock, flags); 101 102 return 0; 103} 104 105/** 106 * xgpio_dir_out - Set the direction of the specified GPIO signal as output. 107 * @gc: Pointer to gpio_chip device structure. 108 * @gpio: GPIO signal number. 109 * @val: Value to be written to specified signal. 110 * 111 * This function sets the direction of specified GPIO signal as output. If all 112 * GPIO signals of GPIO chip is configured as input then it returns 113 * error otherwise it returns 0. 114 */ 115static int xgpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val) 116{ 117 unsigned long flags; 118 struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc); 119 struct xgpio_instance *chip = 120 container_of(mm_gc, struct xgpio_instance, mmchip); 121 122 spin_lock_irqsave(&chip->gpio_lock, flags); 123 124 /* Write state of GPIO signal */ 125 if (val) 126 chip->gpio_state |= 1 << gpio; 127 else 128 chip->gpio_state &= ~(1 << gpio); 129 out_be32(mm_gc->regs + XGPIO_DATA_OFFSET, chip->gpio_state); 130 131 /* Clear the GPIO bit in shadow register and set direction as output */ 132 chip->gpio_dir &= (~(1 << gpio)); 133 out_be32(mm_gc->regs + XGPIO_TRI_OFFSET, chip->gpio_dir); 134 135 spin_unlock_irqrestore(&chip->gpio_lock, flags); 136 137 return 0; 138} 139 140/** 141 * xgpio_save_regs - Set initial values of GPIO pins 142 * @mm_gc: pointer to memory mapped GPIO chip structure 143 */ 144static void xgpio_save_regs(struct of_mm_gpio_chip *mm_gc) 145{ 146 struct xgpio_instance *chip = 147 container_of(mm_gc, struct xgpio_instance, mmchip); 148 149 out_be32(mm_gc->regs + XGPIO_DATA_OFFSET, chip->gpio_state); 150 out_be32(mm_gc->regs + XGPIO_TRI_OFFSET, chip->gpio_dir); 151} 152 153/** 154 * xgpio_of_probe - Probe method for the GPIO device. 155 * @np: pointer to device tree node 156 * 157 * This function probes the GPIO device in the device tree. It initializes the 158 * driver data structure. It returns 0, if the driver is bound to the GPIO 159 * device, or a negative value if there is an error. 160 */ 161static int __devinit xgpio_of_probe(struct device_node *np) 162{ 163 struct xgpio_instance *chip; 164 int status = 0; 165 const u32 *tree_info; 166 167 chip = kzalloc(sizeof(*chip), GFP_KERNEL); 168 if (!chip) 169 return -ENOMEM; 170 171 /* Update GPIO state shadow register with default value */ 172 tree_info = of_get_property(np, "xlnx,dout-default", NULL); 173 if (tree_info) 174 chip->gpio_state = *tree_info; 175 176 /* Update GPIO direction shadow register with default value */ 177 chip->gpio_dir = 0xFFFFFFFF; /* By default, all pins are inputs */ 178 tree_info = of_get_property(np, "xlnx,tri-default", NULL); 179 if (tree_info) 180 chip->gpio_dir = *tree_info; 181 182 /* Check device node and parent device node for device width */ 183 chip->mmchip.gc.ngpio = 32; /* By default assume full GPIO controller */ 184 tree_info = of_get_property(np, "xlnx,gpio-width", NULL); 185 if (!tree_info) 186 tree_info = of_get_property(np->parent, 187 "xlnx,gpio-width", NULL); 188 if (tree_info) 189 chip->mmchip.gc.ngpio = *tree_info; 190 191 spin_lock_init(&chip->gpio_lock); 192 193 chip->mmchip.gc.direction_input = xgpio_dir_in; 194 chip->mmchip.gc.direction_output = xgpio_dir_out; 195 chip->mmchip.gc.get = xgpio_get; 196 chip->mmchip.gc.set = xgpio_set; 197 198 chip->mmchip.save_regs = xgpio_save_regs; 199 200 /* Call the OF gpio helper to setup and register the GPIO device */ 201 status = of_mm_gpiochip_add(np, &chip->mmchip); 202 if (status) { 203 kfree(chip); 204 pr_err("%s: error in probe function with status %d\n", 205 np->full_name, status); 206 return status; 207 } 208 pr_info("XGpio: %s: registered\n", np->full_name); 209 return 0; 210} 211 212static struct of_device_id xgpio_of_match[] __devinitdata = { 213 { .compatible = "xlnx,xps-gpio-1.00.a", }, 214 { /* end of list */ }, 215}; 216 217static int __init xgpio_init(void) 218{ 219 struct device_node *np; 220 221 for_each_matching_node(np, xgpio_of_match) 222 xgpio_of_probe(np); 223 224 return 0; 225} 226 227/* Make sure we get initialized before anyone else tries to use us */ 228subsys_initcall(xgpio_init); 229/* No exit call at the moment as we cannot unregister of GPIO chips */ 230 231MODULE_AUTHOR("Xilinx, Inc."); 232MODULE_DESCRIPTION("Xilinx GPIO driver"); 233MODULE_LICENSE("GPL"); 234