dm thin metadata: fix __udivdi3 undefined on 32-bit
[linux/fpc-iii.git] / drivers / gpio / gpio-74x164.c
blob60172f835d15f1398fa8c7ac58901f40d0a5914c
1 /*
2 * 74Hx164 - Generic serial-in/parallel-out 8-bits shift register GPIO driver
4 * Copyright (C) 2010 Gabor Juhos <juhosg@openwrt.org>
5 * Copyright (C) 2010 Miguel Gaio <miguel.gaio@efixo.com>
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.
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>
20 #define GEN_74X164_NUMBER_GPIOS 8
22 struct gen_74x164_chip {
23 u8 *buffer;
24 struct gpio_chip gpio_chip;
25 struct mutex lock;
26 u32 registers;
29 static struct gen_74x164_chip *gpio_to_74x164_chip(struct gpio_chip *gc)
31 return container_of(gc, struct gen_74x164_chip, gpio_chip);
34 static int __gen_74x164_write_config(struct gen_74x164_chip *chip)
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;
41 msg_buf = kzalloc(chip->registers * sizeof(struct spi_transfer),
42 GFP_KERNEL);
43 if (!msg_buf)
44 return -ENOMEM;
46 spi_message_init(&message);
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.
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);
62 ret = spi_sync(spi, &message);
64 kfree(msg_buf);
66 return ret;
69 static int gen_74x164_get_value(struct gpio_chip *gc, unsigned offset)
71 struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc);
72 u8 bank = offset / 8;
73 u8 pin = offset % 8;
74 int ret;
76 mutex_lock(&chip->lock);
77 ret = (chip->buffer[bank] >> pin) & 0x1;
78 mutex_unlock(&chip->lock);
80 return ret;
83 static void gen_74x164_set_value(struct gpio_chip *gc,
84 unsigned offset, int val)
86 struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc);
87 u8 bank = offset / 8;
88 u8 pin = offset % 8;
90 mutex_lock(&chip->lock);
91 if (val)
92 chip->buffer[bank] |= (1 << pin);
93 else
94 chip->buffer[bank] &= ~(1 << pin);
96 __gen_74x164_write_config(chip);
97 mutex_unlock(&chip->lock);
100 static int gen_74x164_direction_output(struct gpio_chip *gc,
101 unsigned offset, int val)
103 gen_74x164_set_value(gc, offset, val);
104 return 0;
107 static int gen_74x164_probe(struct spi_device *spi)
109 struct gen_74x164_chip *chip;
110 int ret;
113 * bits_per_word cannot be configured in platform data
115 spi->bits_per_word = 8;
117 ret = spi_setup(spi);
118 if (ret < 0)
119 return ret;
121 chip = devm_kzalloc(&spi->dev, sizeof(*chip), GFP_KERNEL);
122 if (!chip)
123 return -ENOMEM;
125 spi_set_drvdata(spi, chip);
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;
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;
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;
145 chip->gpio_chip.can_sleep = true;
146 chip->gpio_chip.dev = &spi->dev;
147 chip->gpio_chip.owner = THIS_MODULE;
149 mutex_init(&chip->lock);
151 ret = __gen_74x164_write_config(chip);
152 if (ret) {
153 dev_err(&spi->dev, "Failed writing: %d\n", ret);
154 goto exit_destroy;
157 ret = gpiochip_add(&chip->gpio_chip);
158 if (!ret)
159 return 0;
161 exit_destroy:
162 mutex_destroy(&chip->lock);
164 return ret;
167 static int gen_74x164_remove(struct spi_device *spi)
169 struct gen_74x164_chip *chip = spi_get_drvdata(spi);
171 gpiochip_remove(&chip->gpio_chip);
172 mutex_destroy(&chip->lock);
174 return 0;
177 static const struct of_device_id gen_74x164_dt_ids[] = {
178 { .compatible = "fairchild,74hc595" },
181 MODULE_DEVICE_TABLE(of, gen_74x164_dt_ids);
183 static struct spi_driver gen_74x164_driver = {
184 .driver = {
185 .name = "74x164",
186 .of_match_table = gen_74x164_dt_ids,
188 .probe = gen_74x164_probe,
189 .remove = gen_74x164_remove,
191 module_spi_driver(gen_74x164_driver);
193 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
194 MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.com>");
195 MODULE_DESCRIPTION("GPIO expander driver for 74X164 8-bits shift register");
196 MODULE_LICENSE("GPL v2");