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
  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");