drivers/gpio/xilinx_gpio.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/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
  28 struct 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  */
  43 static 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  */
  59 static 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  */
  87 static 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  */
 115 static 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  */
 144 static 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  */
 161 static 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 = be32_to_cpup(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 = be32_to_cpup(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 = be32_to_cpup(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
 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");