tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
29struct 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 */
44static 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 */
60static 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 */
88static 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 */
116static 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 */
145static 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 */
162static 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
212static struct of_device_id xgpio_of_match[] __devinitdata = {
213 { .compatible = "xlnx,xps-gpio-1.00.a", },
214 { /* end of list */ },
215};
216
217static 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 */
228subsys_initcall(xgpio_init);
229/* No exit call at the moment as we cannot unregister of GPIO chips */
230
231MODULE_AUTHOR("Xilinx, Inc.");
232MODULE_DESCRIPTION("Xilinx GPIO driver");
233MODULE_LICENSE("GPL");