1/*
2 *  GPIO interface for IT8761E Super I/O chip
3 *
4 *  Author: Denis Turischev <denis@compulab.co.il>
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 2 as published
8 *  by the Free Software Foundation.
9 *
10 *  This program is distributed in the hope that it will be useful,
11 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
12 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 *  GNU General Public License for more details.
14 *
15 *  You should have received a copy of the GNU General Public License
16 *  along with this program; see the file COPYING.  If not, write to
17 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
18 */
19
20#include <linux/init.h>
21#include <linux/kernel.h>
22#include <linux/module.h>
23#include <linux/io.h>
24#include <linux/errno.h>
25#include <linux/ioport.h>
26
27#include <linux/gpio.h>
28
29#define SIO_CHIP_ID		0x8761
30#define CHIP_ID_HIGH_BYTE	0x20
31#define CHIP_ID_LOW_BYTE	0x21
32
33static u8 ports[2] = { 0x2e, 0x4e };
34static u8 port;
35
36static DEFINE_SPINLOCK(sio_lock);
37
38#define GPIO_NAME		"it8761-gpio"
39#define GPIO_BA_HIGH_BYTE	0x60
40#define GPIO_BA_LOW_BYTE	0x61
41#define GPIO_IOSIZE		4
42#define GPIO1X_IO		0xf0
43#define GPIO2X_IO		0xf1
44
45static u16 gpio_ba;
46
47static u8 read_reg(u8 addr, u8 port)
48{
49	outb(addr, port);
50	return inb(port + 1);
51}
52
53static void write_reg(u8 data, u8 addr, u8 port)
54{
55	outb(addr, port);
56	outb(data, port + 1);
57}
58
59static void enter_conf_mode(u8 port)
60{
61	outb(0x87, port);
62	outb(0x61, port);
63	outb(0x55, port);
64	outb((port == 0x2e) ? 0x55 : 0xaa, port);
65}
66
67static void exit_conf_mode(u8 port)
68{
69	outb(0x2, port);
70	outb(0x2, port + 1);
71}
72
73static void enter_gpio_mode(u8 port)
74{
75	write_reg(0x2, 0x7, port);
76}
77
78static int it8761e_gpio_get(struct gpio_chip *gc, unsigned gpio_num)
79{
80	u16 reg;
81	u8 bit;
82
83	bit = gpio_num % 8;
84	reg = (gpio_num >= 8) ? gpio_ba + 1 : gpio_ba;
85
86	return !!(inb(reg) & (1 << bit));
87}
88
89static int it8761e_gpio_direction_in(struct gpio_chip *gc, unsigned gpio_num)
90{
91	u8 curr_dirs;
92	u8 io_reg, bit;
93
94	bit = gpio_num % 8;
95	io_reg = (gpio_num >= 8) ? GPIO2X_IO : GPIO1X_IO;
96
97	spin_lock(&sio_lock);
98
99	enter_conf_mode(port);
100	enter_gpio_mode(port);
101
102	curr_dirs = read_reg(io_reg, port);
103
104	if (curr_dirs & (1 << bit))
105		write_reg(curr_dirs & ~(1 << bit), io_reg, port);
106
107	exit_conf_mode(port);
108
109	spin_unlock(&sio_lock);
110	return 0;
111}
112
113static void it8761e_gpio_set(struct gpio_chip *gc,
114				unsigned gpio_num, int val)
115{
116	u8 curr_vals, bit;
117	u16 reg;
118
119	bit = gpio_num % 8;
120	reg = (gpio_num >= 8) ? gpio_ba + 1 : gpio_ba;
121
122	spin_lock(&sio_lock);
123
124	curr_vals = inb(reg);
125	if (val)
126		outb(curr_vals | (1 << bit) , reg);
127	else
128		outb(curr_vals & ~(1 << bit), reg);
129
130	spin_unlock(&sio_lock);
131}
132
133static int it8761e_gpio_direction_out(struct gpio_chip *gc,
134					unsigned gpio_num, int val)
135{
136	u8 curr_dirs, io_reg, bit;
137
138	bit = gpio_num % 8;
139	io_reg = (gpio_num >= 8) ? GPIO2X_IO : GPIO1X_IO;
140
141	it8761e_gpio_set(gc, gpio_num, val);
142
143	spin_lock(&sio_lock);
144
145	enter_conf_mode(port);
146	enter_gpio_mode(port);
147
148	curr_dirs = read_reg(io_reg, port);
149
150	if (!(curr_dirs & (1 << bit)))
151		write_reg(curr_dirs | (1 << bit), io_reg, port);
152
153	exit_conf_mode(port);
154
155	spin_unlock(&sio_lock);
156	return 0;
157}
158
159static struct gpio_chip it8761e_gpio_chip = {
160	.label			= GPIO_NAME,
161	.owner			= THIS_MODULE,
162	.get			= it8761e_gpio_get,
163	.direction_input	= it8761e_gpio_direction_in,
164	.set			= it8761e_gpio_set,
165	.direction_output	= it8761e_gpio_direction_out,
166};
167
168static int __init it8761e_gpio_init(void)
169{
170	int i, id, err;
171
172	/* chip and port detection */
173	for (i = 0; i < ARRAY_SIZE(ports); i++) {
174		spin_lock(&sio_lock);
175		enter_conf_mode(ports[i]);
176
177		id = (read_reg(CHIP_ID_HIGH_BYTE, ports[i]) << 8) +
178				read_reg(CHIP_ID_LOW_BYTE, ports[i]);
179
180		exit_conf_mode(ports[i]);
181		spin_unlock(&sio_lock);
182
183		if (id == SIO_CHIP_ID) {
184			port = ports[i];
185			break;
186		}
187	}
188
189	if (!port)
190		return -ENODEV;
191
192	/* fetch GPIO base address */
193	enter_conf_mode(port);
194	enter_gpio_mode(port);
195	gpio_ba = (read_reg(GPIO_BA_HIGH_BYTE, port) << 8) +
196				read_reg(GPIO_BA_LOW_BYTE, port);
197	exit_conf_mode(port);
198
199	if (!request_region(gpio_ba, GPIO_IOSIZE, GPIO_NAME))
200		return -EBUSY;
201
202	it8761e_gpio_chip.base = -1;
203	it8761e_gpio_chip.ngpio = 16;
204
205	err = gpiochip_add(&it8761e_gpio_chip);
206	if (err < 0)
207		goto gpiochip_add_err;
208
209	return 0;
210
211gpiochip_add_err:
212	release_region(gpio_ba, GPIO_IOSIZE);
213	gpio_ba = 0;
214	return err;
215}
216
217static void __exit it8761e_gpio_exit(void)
218{
219	if (gpio_ba) {
220		gpiochip_remove(&it8761e_gpio_chip);
221		release_region(gpio_ba, GPIO_IOSIZE);
222		gpio_ba = 0;
223	}
224}
225module_init(it8761e_gpio_init);
226module_exit(it8761e_gpio_exit);
227
228MODULE_AUTHOR("Denis Turischev <denis@compulab.co.il>");
229MODULE_DESCRIPTION("GPIO interface for IT8761E Super I/O chip");
230MODULE_LICENSE("GPL");
231