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1/*
2 * 74Hx164 - Generic serial-in/parallel-out 8-bits shift register GPIO driver
3 *
4 * Copyright (C) 2010 Gabor Juhos <juhosg@openwrt.org>
5 * Copyright (C) 2010 Miguel Gaio <miguel.gaio@efixo.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11
12#include <linux/init.h>
13#include <linux/mutex.h>
14#include <linux/spi/spi.h>
15#include <linux/gpio.h>
16#include <linux/of_gpio.h>
17#include <linux/slab.h>
18#include <linux/module.h>
19
20#define GEN_74X164_NUMBER_GPIOS 8
21
22struct gen_74x164_chip {
23 u8 *buffer;
24 struct gpio_chip gpio_chip;
25 struct mutex lock;
26 u32 registers;
27};
28
29static struct gen_74x164_chip *gpio_to_74x164_chip(struct gpio_chip *gc)
30{
31 return container_of(gc, struct gen_74x164_chip, gpio_chip);
32}
33
34static int __gen_74x164_write_config(struct gen_74x164_chip *chip)
35{
36 struct spi_device *spi = to_spi_device(chip->gpio_chip.dev);
37 struct spi_message message;
38 struct spi_transfer *msg_buf;
39 int i, ret = 0;
40
41 msg_buf = kzalloc(chip->registers * sizeof(struct spi_transfer),
42 GFP_KERNEL);
43 if (!msg_buf)
44 return -ENOMEM;
45
46 spi_message_init(&message);
47
48 /*
49 * Since the registers are chained, every byte sent will make
50 * the previous byte shift to the next register in the
51 * chain. Thus, the first byte send will end up in the last
52 * register at the end of the transfer. So, to have a logical
53 * numbering, send the bytes in reverse order so that the last
54 * byte of the buffer will end up in the last register.
55 */
56 for (i = chip->registers - 1; i >= 0; i--) {
57 msg_buf[i].tx_buf = chip->buffer + i;
58 msg_buf[i].len = sizeof(u8);
59 spi_message_add_tail(msg_buf + i, &message);
60 }
61
62 ret = spi_sync(spi, &message);
63
64 kfree(msg_buf);
65
66 return ret;
67}
68
69static int gen_74x164_get_value(struct gpio_chip *gc, unsigned offset)
70{
71 struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc);
72 u8 bank = offset / 8;
73 u8 pin = offset % 8;
74 int ret;
75
76 mutex_lock(&chip->lock);
77 ret = (chip->buffer[bank] >> pin) & 0x1;
78 mutex_unlock(&chip->lock);
79
80 return ret;
81}
82
83static void gen_74x164_set_value(struct gpio_chip *gc,
84 unsigned offset, int val)
85{
86 struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc);
87 u8 bank = offset / 8;
88 u8 pin = offset % 8;
89
90 mutex_lock(&chip->lock);
91 if (val)
92 chip->buffer[bank] |= (1 << pin);
93 else
94 chip->buffer[bank] &= ~(1 << pin);
95
96 __gen_74x164_write_config(chip);
97 mutex_unlock(&chip->lock);
98}
99
100static int gen_74x164_direction_output(struct gpio_chip *gc,
101 unsigned offset, int val)
102{
103 gen_74x164_set_value(gc, offset, val);
104 return 0;
105}
106
107static int gen_74x164_probe(struct spi_device *spi)
108{
109 struct gen_74x164_chip *chip;
110 int ret;
111
112 /*
113 * bits_per_word cannot be configured in platform data
114 */
115 spi->bits_per_word = 8;
116
117 ret = spi_setup(spi);
118 if (ret < 0)
119 return ret;
120
121 chip = devm_kzalloc(&spi->dev, sizeof(*chip), GFP_KERNEL);
122 if (!chip)
123 return -ENOMEM;
124
125 spi_set_drvdata(spi, chip);
126
127 chip->gpio_chip.label = spi->modalias;
128 chip->gpio_chip.direction_output = gen_74x164_direction_output;
129 chip->gpio_chip.get = gen_74x164_get_value;
130 chip->gpio_chip.set = gen_74x164_set_value;
131 chip->gpio_chip.base = -1;
132
133 if (of_property_read_u32(spi->dev.of_node, "registers-number",
134 &chip->registers)) {
135 dev_err(&spi->dev,
136 "Missing registers-number property in the DT.\n");
137 return -EINVAL;
138 }
139
140 chip->gpio_chip.ngpio = GEN_74X164_NUMBER_GPIOS * chip->registers;
141 chip->buffer = devm_kzalloc(&spi->dev, chip->registers, GFP_KERNEL);
142 if (!chip->buffer)
143 return -ENOMEM;
144
145 chip->gpio_chip.can_sleep = true;
146 chip->gpio_chip.dev = &spi->dev;
147 chip->gpio_chip.owner = THIS_MODULE;
148
149 mutex_init(&chip->lock);
150
151 ret = __gen_74x164_write_config(chip);
152 if (ret) {
153 dev_err(&spi->dev, "Failed writing: %d\n", ret);
154 goto exit_destroy;
155 }
156
157 ret = gpiochip_add(&chip->gpio_chip);
158 if (!ret)
159 return 0;
160
161exit_destroy:
162 mutex_destroy(&chip->lock);
163
164 return ret;
165}
166
167static int gen_74x164_remove(struct spi_device *spi)
168{
169 struct gen_74x164_chip *chip = spi_get_drvdata(spi);
170 int ret;
171
172 ret = gpiochip_remove(&chip->gpio_chip);
173 if (!ret)
174 mutex_destroy(&chip->lock);
175
176 return ret;
177}
178
179static const struct of_device_id gen_74x164_dt_ids[] = {
180 { .compatible = "fairchild,74hc595" },
181 {},
182};
183MODULE_DEVICE_TABLE(of, gen_74x164_dt_ids);
184
185static struct spi_driver gen_74x164_driver = {
186 .driver = {
187 .name = "74x164",
188 .owner = THIS_MODULE,
189 .of_match_table = gen_74x164_dt_ids,
190 },
191 .probe = gen_74x164_probe,
192 .remove = gen_74x164_remove,
193};
194module_spi_driver(gen_74x164_driver);
195
196MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
197MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.com>");
198MODULE_DESCRIPTION("GPIO expander driver for 74X164 8-bits shift register");
199MODULE_LICENSE("GPL v2");
1/*
2 * 74Hx164 - Generic serial-in/parallel-out 8-bits shift register GPIO driver
3 *
4 * Copyright (C) 2010 Gabor Juhos <juhosg@openwrt.org>
5 * Copyright (C) 2010 Miguel Gaio <miguel.gaio@efixo.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11
12#include <linux/init.h>
13#include <linux/mutex.h>
14#include <linux/spi/spi.h>
15#include <linux/spi/74x164.h>
16#include <linux/gpio.h>
17#include <linux/slab.h>
18#include <linux/module.h>
19
20struct gen_74x164_chip {
21 struct spi_device *spi;
22 struct gpio_chip gpio_chip;
23 struct mutex lock;
24 u8 port_config;
25};
26
27static struct gen_74x164_chip *gpio_to_74x164_chip(struct gpio_chip *gc)
28{
29 return container_of(gc, struct gen_74x164_chip, gpio_chip);
30}
31
32static int __gen_74x164_write_config(struct gen_74x164_chip *chip)
33{
34 return spi_write(chip->spi,
35 &chip->port_config, sizeof(chip->port_config));
36}
37
38static int gen_74x164_get_value(struct gpio_chip *gc, unsigned offset)
39{
40 struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc);
41 int ret;
42
43 mutex_lock(&chip->lock);
44 ret = (chip->port_config >> offset) & 0x1;
45 mutex_unlock(&chip->lock);
46
47 return ret;
48}
49
50static void gen_74x164_set_value(struct gpio_chip *gc,
51 unsigned offset, int val)
52{
53 struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc);
54
55 mutex_lock(&chip->lock);
56 if (val)
57 chip->port_config |= (1 << offset);
58 else
59 chip->port_config &= ~(1 << offset);
60
61 __gen_74x164_write_config(chip);
62 mutex_unlock(&chip->lock);
63}
64
65static int gen_74x164_direction_output(struct gpio_chip *gc,
66 unsigned offset, int val)
67{
68 gen_74x164_set_value(gc, offset, val);
69 return 0;
70}
71
72static int __devinit gen_74x164_probe(struct spi_device *spi)
73{
74 struct gen_74x164_chip *chip;
75 struct gen_74x164_chip_platform_data *pdata;
76 int ret;
77
78 pdata = spi->dev.platform_data;
79 if (!pdata || !pdata->base) {
80 dev_dbg(&spi->dev, "incorrect or missing platform data\n");
81 return -EINVAL;
82 }
83
84 /*
85 * bits_per_word cannot be configured in platform data
86 */
87 spi->bits_per_word = 8;
88
89 ret = spi_setup(spi);
90 if (ret < 0)
91 return ret;
92
93 chip = kzalloc(sizeof(*chip), GFP_KERNEL);
94 if (!chip)
95 return -ENOMEM;
96
97 mutex_init(&chip->lock);
98
99 dev_set_drvdata(&spi->dev, chip);
100
101 chip->spi = spi;
102
103 chip->gpio_chip.label = spi->modalias;
104 chip->gpio_chip.direction_output = gen_74x164_direction_output;
105 chip->gpio_chip.get = gen_74x164_get_value;
106 chip->gpio_chip.set = gen_74x164_set_value;
107 chip->gpio_chip.base = pdata->base;
108 chip->gpio_chip.ngpio = 8;
109 chip->gpio_chip.can_sleep = 1;
110 chip->gpio_chip.dev = &spi->dev;
111 chip->gpio_chip.owner = THIS_MODULE;
112
113 ret = __gen_74x164_write_config(chip);
114 if (ret) {
115 dev_err(&spi->dev, "Failed writing: %d\n", ret);
116 goto exit_destroy;
117 }
118
119 ret = gpiochip_add(&chip->gpio_chip);
120 if (ret)
121 goto exit_destroy;
122
123 return ret;
124
125exit_destroy:
126 dev_set_drvdata(&spi->dev, NULL);
127 mutex_destroy(&chip->lock);
128 kfree(chip);
129 return ret;
130}
131
132static int __devexit gen_74x164_remove(struct spi_device *spi)
133{
134 struct gen_74x164_chip *chip;
135 int ret;
136
137 chip = dev_get_drvdata(&spi->dev);
138 if (chip == NULL)
139 return -ENODEV;
140
141 dev_set_drvdata(&spi->dev, NULL);
142
143 ret = gpiochip_remove(&chip->gpio_chip);
144 if (!ret) {
145 mutex_destroy(&chip->lock);
146 kfree(chip);
147 } else
148 dev_err(&spi->dev, "Failed to remove the GPIO controller: %d\n",
149 ret);
150
151 return ret;
152}
153
154static struct spi_driver gen_74x164_driver = {
155 .driver = {
156 .name = "74x164",
157 .owner = THIS_MODULE,
158 },
159 .probe = gen_74x164_probe,
160 .remove = __devexit_p(gen_74x164_remove),
161};
162
163static int __init gen_74x164_init(void)
164{
165 return spi_register_driver(&gen_74x164_driver);
166}
167subsys_initcall(gen_74x164_init);
168
169static void __exit gen_74x164_exit(void)
170{
171 spi_unregister_driver(&gen_74x164_driver);
172}
173module_exit(gen_74x164_exit);
174
175MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
176MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.com>");
177MODULE_DESCRIPTION("GPIO expander driver for 74X164 8-bits shift register");
178MODULE_LICENSE("GPL v2");