drivers/gpio/gpio-xilinx.c

   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 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[] = {
 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");