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/module.h> 18 #include <linux/of_device.h> 19 #include <linux/of_platform.h> 20 #include <linux/of_gpio.h> 21 #include <linux/io.h> 22 #include <linux/gpio.h> 23 #include <linux/slab.h> 24 25 /* Register Offset Definitions */ 26 #define XGPIO_DATA_OFFSET (0x0) /* Data register */ 27 #define XGPIO_TRI_OFFSET (0x4) /* I/O direction register */ 28 29 struct xgpio_instance { 30 struct of_mm_gpio_chip mmchip; 31 u32 gpio_state; /* GPIO state shadow register */ 32 u32 gpio_dir; /* GPIO direction shadow register */ 33 spinlock_t gpio_lock; /* Lock used for synchronization */ 34 }; 35 36 /** 37 * xgpio_get - Read the specified signal of the GPIO device. 38 * @gc: Pointer to gpio_chip device structure. 39 * @gpio: GPIO signal number. 40 * 41 * This function reads the specified signal of the GPIO device. It returns 0 if 42 * the signal clear, 1 if signal is set or negative value on error. 43 */ 44 static int xgpio_get(struct gpio_chip *gc, unsigned int gpio) 45 { 46 struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc); 47 48 return (in_be32(mm_gc->regs + XGPIO_DATA_OFFSET) >> gpio) & 1; 49 } 50 51 /** 52 * xgpio_set - Write the specified signal of the GPIO device. 53 * @gc: Pointer to gpio_chip device structure. 54 * @gpio: GPIO signal number. 55 * @val: Value to be written to specified signal. 56 * 57 * This function writes the specified value in to the specified signal of the 58 * GPIO device. 59 */ 60 static void xgpio_set(struct gpio_chip *gc, unsigned int gpio, int val) 61 { 62 unsigned long flags; 63 struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc); 64 struct xgpio_instance *chip = 65 container_of(mm_gc, struct xgpio_instance, mmchip); 66 67 spin_lock_irqsave(&chip->gpio_lock, flags); 68 69 /* Write to GPIO signal and set its direction to output */ 70 if (val) 71 chip->gpio_state |= 1 << gpio; 72 else 73 chip->gpio_state &= ~(1 << gpio); 74 out_be32(mm_gc->regs + XGPIO_DATA_OFFSET, chip->gpio_state); 75 76 spin_unlock_irqrestore(&chip->gpio_lock, flags); 77 } 78 79 /** 80 * xgpio_dir_in - Set the direction of the specified GPIO signal as input. 81 * @gc: Pointer to gpio_chip device structure. 82 * @gpio: GPIO signal number. 83 * 84 * This function sets the direction of specified GPIO signal as input. 85 * It returns 0 if direction of GPIO signals is set as input otherwise it 86 * returns negative error value. 87 */ 88 static int xgpio_dir_in(struct gpio_chip *gc, unsigned int gpio) 89 { 90 unsigned long flags; 91 struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc); 92 struct xgpio_instance *chip = 93 container_of(mm_gc, struct xgpio_instance, mmchip); 94 95 spin_lock_irqsave(&chip->gpio_lock, flags); 96 97 /* Set the GPIO bit in shadow register and set direction as input */ 98 chip->gpio_dir |= (1 << gpio); 99 out_be32(mm_gc->regs + XGPIO_TRI_OFFSET, chip->gpio_dir); 100 101 spin_unlock_irqrestore(&chip->gpio_lock, flags); 102 103 return 0; 104 } 105 106 /** 107 * xgpio_dir_out - Set the direction of the specified GPIO signal as output. 108 * @gc: Pointer to gpio_chip device structure. 109 * @gpio: GPIO signal number. 110 * @val: Value to be written to specified signal. 111 * 112 * This function sets the direction of specified GPIO signal as output. If all 113 * GPIO signals of GPIO chip is configured as input then it returns 114 * error otherwise it returns 0. 115 */ 116 static int xgpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val) 117 { 118 unsigned long flags; 119 struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc); 120 struct xgpio_instance *chip = 121 container_of(mm_gc, struct xgpio_instance, mmchip); 122 123 spin_lock_irqsave(&chip->gpio_lock, flags); 124 125 /* Write state of GPIO signal */ 126 if (val) 127 chip->gpio_state |= 1 << gpio; 128 else 129 chip->gpio_state &= ~(1 << gpio); 130 out_be32(mm_gc->regs + XGPIO_DATA_OFFSET, chip->gpio_state); 131 132 /* Clear the GPIO bit in shadow register and set direction as output */ 133 chip->gpio_dir &= (~(1 << gpio)); 134 out_be32(mm_gc->regs + XGPIO_TRI_OFFSET, chip->gpio_dir); 135 136 spin_unlock_irqrestore(&chip->gpio_lock, flags); 137 138 return 0; 139 } 140 141 /** 142 * xgpio_save_regs - Set initial values of GPIO pins 143 * @mm_gc: pointer to memory mapped GPIO chip structure 144 */ 145 static void xgpio_save_regs(struct of_mm_gpio_chip *mm_gc) 146 { 147 struct xgpio_instance *chip = 148 container_of(mm_gc, struct xgpio_instance, mmchip); 149 150 out_be32(mm_gc->regs + XGPIO_DATA_OFFSET, chip->gpio_state); 151 out_be32(mm_gc->regs + XGPIO_TRI_OFFSET, chip->gpio_dir); 152 } 153 154 /** 155 * xgpio_of_probe - Probe method for the GPIO device. 156 * @np: pointer to device tree node 157 * 158 * This function probes the GPIO device in the device tree. It initializes the 159 * driver data structure. It returns 0, if the driver is bound to the GPIO 160 * device, or a negative value if there is an error. 161 */ 162 static int __devinit xgpio_of_probe(struct device_node *np) 163 { 164 struct xgpio_instance *chip; 165 int status = 0; 166 const u32 *tree_info; 167 168 chip = kzalloc(sizeof(*chip), GFP_KERNEL); 169 if (!chip) 170 return -ENOMEM; 171 172 /* Update GPIO state shadow register with default value */ 173 tree_info = of_get_property(np, "xlnx,dout-default", NULL); 174 if (tree_info) 175 chip->gpio_state = be32_to_cpup(tree_info); 176 177 /* Update GPIO direction shadow register with default value */ 178 chip->gpio_dir = 0xFFFFFFFF; /* By default, all pins are inputs */ 179 tree_info = of_get_property(np, "xlnx,tri-default", NULL); 180 if (tree_info) 181 chip->gpio_dir = be32_to_cpup(tree_info); 182 183 /* Check device node and parent device node for device width */ 184 chip->mmchip.gc.ngpio = 32; /* By default assume full GPIO controller */ 185 tree_info = of_get_property(np, "xlnx,gpio-width", NULL); 186 if (!tree_info) 187 tree_info = of_get_property(np->parent, 188 "xlnx,gpio-width", NULL); 189 if (tree_info) 190 chip->mmchip.gc.ngpio = be32_to_cpup(tree_info); 191 192 spin_lock_init(&chip->gpio_lock); 193 194 chip->mmchip.gc.direction_input = xgpio_dir_in; 195 chip->mmchip.gc.direction_output = xgpio_dir_out; 196 chip->mmchip.gc.get = xgpio_get; 197 chip->mmchip.gc.set = xgpio_set; 198 199 chip->mmchip.save_regs = xgpio_save_regs; 200 201 /* Call the OF gpio helper to setup and register the GPIO device */ 202 status = of_mm_gpiochip_add(np, &chip->mmchip); 203 if (status) { 204 kfree(chip); 205 pr_err("%s: error in probe function with status %d\n", 206 np->full_name, status); 207 return status; 208 } 209 return 0; 210 } 211 212 static struct of_device_id xgpio_of_match[] __devinitdata = { 213 { .compatible = "xlnx,xps-gpio-1.00.a", }, 214 { /* end of list */ }, 215 }; 216 217 static 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 */ 228 subsys_initcall(xgpio_init); 229 /* No exit call at the moment as we cannot unregister of GPIO chips */ 230 231 MODULE_AUTHOR("Xilinx, Inc."); 232 MODULE_DESCRIPTION("Xilinx GPIO driver"); 233 MODULE_LICENSE("GPL"); 234