John Linn | 0bcb606 | 2008-11-12 13:25:38 -0800 | [diff] [blame^] | 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 | |
| 23 | /* Register Offset Definitions */ |
| 24 | #define XGPIO_DATA_OFFSET (0x0) /* Data register */ |
| 25 | #define XGPIO_TRI_OFFSET (0x4) /* I/O direction register */ |
| 26 | |
| 27 | struct xgpio_instance { |
| 28 | struct of_mm_gpio_chip mmchip; |
| 29 | u32 gpio_state; /* GPIO state shadow register */ |
| 30 | u32 gpio_dir; /* GPIO direction shadow register */ |
| 31 | spinlock_t gpio_lock; /* Lock used for synchronization */ |
| 32 | }; |
| 33 | |
| 34 | /** |
| 35 | * xgpio_get - Read the specified signal of the GPIO device. |
| 36 | * @gc: Pointer to gpio_chip device structure. |
| 37 | * @gpio: GPIO signal number. |
| 38 | * |
| 39 | * This function reads the specified signal of the GPIO device. It returns 0 if |
| 40 | * the signal clear, 1 if signal is set or negative value on error. |
| 41 | */ |
| 42 | static int xgpio_get(struct gpio_chip *gc, unsigned int gpio) |
| 43 | { |
| 44 | struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc); |
| 45 | |
| 46 | return (in_be32(mm_gc->regs + XGPIO_DATA_OFFSET) >> gpio) & 1; |
| 47 | } |
| 48 | |
| 49 | /** |
| 50 | * xgpio_set - Write the specified signal of the GPIO device. |
| 51 | * @gc: Pointer to gpio_chip device structure. |
| 52 | * @gpio: GPIO signal number. |
| 53 | * @val: Value to be written to specified signal. |
| 54 | * |
| 55 | * This function writes the specified value in to the specified signal of the |
| 56 | * GPIO device. |
| 57 | */ |
| 58 | static void xgpio_set(struct gpio_chip *gc, unsigned int gpio, int val) |
| 59 | { |
| 60 | unsigned long flags; |
| 61 | struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc); |
| 62 | struct xgpio_instance *chip = |
| 63 | container_of(mm_gc, struct xgpio_instance, mmchip); |
| 64 | |
| 65 | spin_lock_irqsave(&chip->gpio_lock, flags); |
| 66 | |
| 67 | /* Write to GPIO signal and set its direction to output */ |
| 68 | if (val) |
| 69 | chip->gpio_state |= 1 << gpio; |
| 70 | else |
| 71 | chip->gpio_state &= ~(1 << gpio); |
| 72 | out_be32(mm_gc->regs + XGPIO_DATA_OFFSET, chip->gpio_state); |
| 73 | |
| 74 | spin_unlock_irqrestore(&chip->gpio_lock, flags); |
| 75 | } |
| 76 | |
| 77 | /** |
| 78 | * xgpio_dir_in - Set the direction of the specified GPIO signal as input. |
| 79 | * @gc: Pointer to gpio_chip device structure. |
| 80 | * @gpio: GPIO signal number. |
| 81 | * |
| 82 | * This function sets the direction of specified GPIO signal as input. |
| 83 | * It returns 0 if direction of GPIO signals is set as input otherwise it |
| 84 | * returns negative error value. |
| 85 | */ |
| 86 | static int xgpio_dir_in(struct gpio_chip *gc, unsigned int gpio) |
| 87 | { |
| 88 | unsigned long flags; |
| 89 | struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc); |
| 90 | struct xgpio_instance *chip = |
| 91 | container_of(mm_gc, struct xgpio_instance, mmchip); |
| 92 | |
| 93 | spin_lock_irqsave(&chip->gpio_lock, flags); |
| 94 | |
| 95 | /* Set the GPIO bit in shadow register and set direction as input */ |
| 96 | chip->gpio_dir |= (1 << gpio); |
| 97 | out_be32(mm_gc->regs + XGPIO_TRI_OFFSET, chip->gpio_dir); |
| 98 | |
| 99 | spin_unlock_irqrestore(&chip->gpio_lock, flags); |
| 100 | |
| 101 | return 0; |
| 102 | } |
| 103 | |
| 104 | /** |
| 105 | * xgpio_dir_out - Set the direction of the specified GPIO signal as output. |
| 106 | * @gc: Pointer to gpio_chip device structure. |
| 107 | * @gpio: GPIO signal number. |
| 108 | * @val: Value to be written to specified signal. |
| 109 | * |
| 110 | * This function sets the direction of specified GPIO signal as output. If all |
| 111 | * GPIO signals of GPIO chip is configured as input then it returns |
| 112 | * error otherwise it returns 0. |
| 113 | */ |
| 114 | static int xgpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val) |
| 115 | { |
| 116 | unsigned long flags; |
| 117 | struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc); |
| 118 | struct xgpio_instance *chip = |
| 119 | container_of(mm_gc, struct xgpio_instance, mmchip); |
| 120 | |
| 121 | spin_lock_irqsave(&chip->gpio_lock, flags); |
| 122 | |
| 123 | /* Write state of GPIO signal */ |
| 124 | if (val) |
| 125 | chip->gpio_state |= 1 << gpio; |
| 126 | else |
| 127 | chip->gpio_state &= ~(1 << gpio); |
| 128 | out_be32(mm_gc->regs + XGPIO_DATA_OFFSET, chip->gpio_state); |
| 129 | |
| 130 | /* Clear the GPIO bit in shadow register and set direction as output */ |
| 131 | chip->gpio_dir &= (~(1 << gpio)); |
| 132 | out_be32(mm_gc->regs + XGPIO_TRI_OFFSET, chip->gpio_dir); |
| 133 | |
| 134 | spin_unlock_irqrestore(&chip->gpio_lock, flags); |
| 135 | |
| 136 | return 0; |
| 137 | } |
| 138 | |
| 139 | /** |
| 140 | * xgpio_save_regs - Set initial values of GPIO pins |
| 141 | * @mm_gc: pointer to memory mapped GPIO chip structure |
| 142 | */ |
| 143 | static void xgpio_save_regs(struct of_mm_gpio_chip *mm_gc) |
| 144 | { |
| 145 | struct xgpio_instance *chip = |
| 146 | container_of(mm_gc, struct xgpio_instance, mmchip); |
| 147 | |
| 148 | out_be32(mm_gc->regs + XGPIO_DATA_OFFSET, chip->gpio_state); |
| 149 | out_be32(mm_gc->regs + XGPIO_TRI_OFFSET, chip->gpio_dir); |
| 150 | } |
| 151 | |
| 152 | /** |
| 153 | * xgpio_of_probe - Probe method for the GPIO device. |
| 154 | * @np: pointer to device tree node |
| 155 | * |
| 156 | * This function probes the GPIO device in the device tree. It initializes the |
| 157 | * driver data structure. It returns 0, if the driver is bound to the GPIO |
| 158 | * device, or a negative value if there is an error. |
| 159 | */ |
| 160 | static int __devinit xgpio_of_probe(struct device_node *np) |
| 161 | { |
| 162 | struct xgpio_instance *chip; |
| 163 | struct of_gpio_chip *ofchip; |
| 164 | int status = 0; |
| 165 | const u32 *tree_info; |
| 166 | |
| 167 | chip = kzalloc(sizeof(*chip), GFP_KERNEL); |
| 168 | if (!chip) |
| 169 | return -ENOMEM; |
| 170 | ofchip = &chip->mmchip.of_gc; |
| 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 = *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 = *tree_info; |
| 182 | |
| 183 | /* Check device node and parent device node for device width */ |
| 184 | ofchip->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 | ofchip->gc.ngpio = *tree_info; |
| 191 | |
| 192 | spin_lock_init(&chip->gpio_lock); |
| 193 | |
| 194 | ofchip->gpio_cells = 2; |
| 195 | ofchip->gc.direction_input = xgpio_dir_in; |
| 196 | ofchip->gc.direction_output = xgpio_dir_out; |
| 197 | ofchip->gc.get = xgpio_get; |
| 198 | ofchip->gc.set = xgpio_set; |
| 199 | |
| 200 | chip->mmchip.save_regs = xgpio_save_regs; |
| 201 | |
| 202 | /* Call the OF gpio helper to setup and register the GPIO device */ |
| 203 | status = of_mm_gpiochip_add(np, &chip->mmchip); |
| 204 | if (status) { |
| 205 | kfree(chip); |
| 206 | pr_err("%s: error in probe function with status %d\n", |
| 207 | np->full_name, status); |
| 208 | return status; |
| 209 | } |
| 210 | pr_info("XGpio: %s: registered\n", np->full_name); |
| 211 | return 0; |
| 212 | } |
| 213 | |
| 214 | static struct of_device_id xgpio_of_match[] __devinitdata = { |
| 215 | { .compatible = "xlnx,xps-gpio-1.00.a", }, |
| 216 | { /* end of list */ }, |
| 217 | }; |
| 218 | |
| 219 | static int __init xgpio_init(void) |
| 220 | { |
| 221 | struct device_node *np; |
| 222 | |
| 223 | for_each_matching_node(np, xgpio_of_match) |
| 224 | xgpio_of_probe(np); |
| 225 | |
| 226 | return 0; |
| 227 | } |
| 228 | |
| 229 | /* Make sure we get initialized before anyone else tries to use us */ |
| 230 | subsys_initcall(xgpio_init); |
| 231 | /* No exit call at the moment as we cannot unregister of GPIO chips */ |
| 232 | |
| 233 | MODULE_AUTHOR("Xilinx, Inc."); |
| 234 | MODULE_DESCRIPTION("Xilinx GPIO driver"); |
| 235 | MODULE_LICENSE("GPL"); |