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ead6db08 MG |
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> | |
ead6db08 | 15 | #include <linux/gpio.h> |
20bc4d5d | 16 | #include <linux/of_gpio.h> |
ead6db08 | 17 | #include <linux/slab.h> |
bb207ef1 | 18 | #include <linux/module.h> |
ead6db08 | 19 | |
20bc4d5d MR |
20 | #define GEN_74X164_NUMBER_GPIOS 8 |
21 | ||
ead6db08 | 22 | struct gen_74x164_chip { |
20bc4d5d | 23 | u8 *buffer; |
ead6db08 MG |
24 | struct gpio_chip gpio_chip; |
25 | struct mutex lock; | |
20bc4d5d | 26 | u32 registers; |
ead6db08 MG |
27 | }; |
28 | ||
12610be3 | 29 | static struct gen_74x164_chip *gpio_to_74x164_chip(struct gpio_chip *gc) |
ead6db08 MG |
30 | { |
31 | return container_of(gc, struct gen_74x164_chip, gpio_chip); | |
32 | } | |
33 | ||
34 | static int __gen_74x164_write_config(struct gen_74x164_chip *chip) | |
35 | { | |
bcc0562c | 36 | struct spi_device *spi = to_spi_device(chip->gpio_chip.dev); |
20bc4d5d MR |
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--) { | |
bcc0562c | 57 | msg_buf[i].tx_buf = chip->buffer + i; |
20bc4d5d MR |
58 | msg_buf[i].len = sizeof(u8); |
59 | spi_message_add_tail(msg_buf + i, &message); | |
60 | } | |
61 | ||
bcc0562c | 62 | ret = spi_sync(spi, &message); |
20bc4d5d MR |
63 | |
64 | kfree(msg_buf); | |
65 | ||
66 | return ret; | |
ead6db08 MG |
67 | } |
68 | ||
ead6db08 MG |
69 | static int gen_74x164_get_value(struct gpio_chip *gc, unsigned offset) |
70 | { | |
12610be3 | 71 | struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc); |
20bc4d5d MR |
72 | u8 bank = offset / 8; |
73 | u8 pin = offset % 8; | |
ead6db08 MG |
74 | int ret; |
75 | ||
76 | mutex_lock(&chip->lock); | |
20bc4d5d | 77 | ret = (chip->buffer[bank] >> pin) & 0x1; |
ead6db08 MG |
78 | mutex_unlock(&chip->lock); |
79 | ||
80 | return ret; | |
81 | } | |
82 | ||
83 | static void gen_74x164_set_value(struct gpio_chip *gc, | |
84 | unsigned offset, int val) | |
85 | { | |
12610be3 | 86 | struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc); |
20bc4d5d MR |
87 | u8 bank = offset / 8; |
88 | u8 pin = offset % 8; | |
ead6db08 MG |
89 | |
90 | mutex_lock(&chip->lock); | |
91 | if (val) | |
20bc4d5d | 92 | chip->buffer[bank] |= (1 << pin); |
ead6db08 | 93 | else |
20bc4d5d | 94 | chip->buffer[bank] &= ~(1 << pin); |
ead6db08 MG |
95 | |
96 | __gen_74x164_write_config(chip); | |
97 | mutex_unlock(&chip->lock); | |
98 | } | |
99 | ||
a3cc68c3 HS |
100 | static 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 | ||
3836309d | 107 | static int gen_74x164_probe(struct spi_device *spi) |
ead6db08 MG |
108 | { |
109 | struct gen_74x164_chip *chip; | |
ead6db08 MG |
110 | int ret; |
111 | ||
ead6db08 MG |
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 | ||
72eac302 | 121 | chip = devm_kzalloc(&spi->dev, sizeof(*chip), GFP_KERNEL); |
ead6db08 MG |
122 | if (!chip) |
123 | return -ENOMEM; | |
124 | ||
6c0cf42b | 125 | spi_set_drvdata(spi, chip); |
ead6db08 | 126 | |
a3cc68c3 HS |
127 | chip->gpio_chip.label = spi->modalias; |
128 | chip->gpio_chip.direction_output = gen_74x164_direction_output; | |
ead6db08 MG |
129 | chip->gpio_chip.get = gen_74x164_get_value; |
130 | chip->gpio_chip.set = gen_74x164_set_value; | |
61e73804 | 131 | chip->gpio_chip.base = -1; |
20bc4d5d | 132 | |
bcc0562c AS |
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; | |
20bc4d5d MR |
138 | } |
139 | ||
140 | chip->gpio_chip.ngpio = GEN_74X164_NUMBER_GPIOS * chip->registers; | |
a48221a2 | 141 | chip->buffer = devm_kzalloc(&spi->dev, chip->registers, GFP_KERNEL); |
bcc0562c AS |
142 | if (!chip->buffer) |
143 | return -ENOMEM; | |
20bc4d5d | 144 | |
9fb1f39e | 145 | chip->gpio_chip.can_sleep = true; |
ead6db08 MG |
146 | chip->gpio_chip.dev = &spi->dev; |
147 | chip->gpio_chip.owner = THIS_MODULE; | |
148 | ||
bcc0562c AS |
149 | mutex_init(&chip->lock); |
150 | ||
ead6db08 MG |
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); | |
bcc0562c AS |
158 | if (!ret) |
159 | return 0; | |
ead6db08 MG |
160 | |
161 | exit_destroy: | |
ead6db08 | 162 | mutex_destroy(&chip->lock); |
bcc0562c | 163 | |
ead6db08 MG |
164 | return ret; |
165 | } | |
166 | ||
206210ce | 167 | static int gen_74x164_remove(struct spi_device *spi) |
ead6db08 | 168 | { |
bcc0562c | 169 | struct gen_74x164_chip *chip = spi_get_drvdata(spi); |
ead6db08 | 170 | |
9f5132ae | 171 | gpiochip_remove(&chip->gpio_chip); |
172 | mutex_destroy(&chip->lock); | |
ead6db08 | 173 | |
9f5132ae | 174 | return 0; |
ead6db08 MG |
175 | } |
176 | ||
0a90a9fb MR |
177 | static const struct of_device_id gen_74x164_dt_ids[] = { |
178 | { .compatible = "fairchild,74hc595" }, | |
179 | {}, | |
180 | }; | |
181 | MODULE_DEVICE_TABLE(of, gen_74x164_dt_ids); | |
182 | ||
ead6db08 MG |
183 | static struct spi_driver gen_74x164_driver = { |
184 | .driver = { | |
a3cc68c3 | 185 | .name = "74x164", |
ead6db08 | 186 | .owner = THIS_MODULE, |
187a53a5 | 187 | .of_match_table = gen_74x164_dt_ids, |
ead6db08 MG |
188 | }, |
189 | .probe = gen_74x164_probe, | |
8283c4ff | 190 | .remove = gen_74x164_remove, |
ead6db08 | 191 | }; |
ab3b8782 | 192 | module_spi_driver(gen_74x164_driver); |
ead6db08 MG |
193 | |
194 | MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>"); | |
195 | MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.com>"); | |
196 | MODULE_DESCRIPTION("GPIO expander driver for 74X164 8-bits shift register"); | |
197 | MODULE_LICENSE("GPL v2"); |