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/gpio/consumer.h>
13 #include <linux/init.h>
14 #include <linux/mutex.h>
15 #include <linux/spi/spi.h>
16 #include <linux/gpio.h>
17 #include <linux/of_gpio.h>
18 #include <linux/slab.h>
19 #include <linux/module.h>
21 #define GEN_74X164_NUMBER_GPIOS 8
23 struct gen_74x164_chip
{
24 struct gpio_chip gpio_chip
;
28 * Since the registers are chained, every byte sent will make
29 * the previous byte shift to the next register in the
30 * chain. Thus, the first byte sent will end up in the last
31 * register at the end of the transfer. So, to have a logical
32 * numbering, store the bytes in reverse order.
35 struct gpio_desc
*gpiod_oe
;
38 static int __gen_74x164_write_config(struct gen_74x164_chip
*chip
)
40 return spi_write(to_spi_device(chip
->gpio_chip
.parent
), chip
->buffer
,
44 static int gen_74x164_get_value(struct gpio_chip
*gc
, unsigned offset
)
46 struct gen_74x164_chip
*chip
= gpiochip_get_data(gc
);
47 u8 bank
= chip
->registers
- 1 - offset
/ 8;
51 mutex_lock(&chip
->lock
);
52 ret
= (chip
->buffer
[bank
] >> pin
) & 0x1;
53 mutex_unlock(&chip
->lock
);
58 static void gen_74x164_set_value(struct gpio_chip
*gc
,
59 unsigned offset
, int val
)
61 struct gen_74x164_chip
*chip
= gpiochip_get_data(gc
);
62 u8 bank
= chip
->registers
- 1 - offset
/ 8;
65 mutex_lock(&chip
->lock
);
67 chip
->buffer
[bank
] |= (1 << pin
);
69 chip
->buffer
[bank
] &= ~(1 << pin
);
71 __gen_74x164_write_config(chip
);
72 mutex_unlock(&chip
->lock
);
75 static void gen_74x164_set_multiple(struct gpio_chip
*gc
, unsigned long *mask
,
78 struct gen_74x164_chip
*chip
= gpiochip_get_data(gc
);
79 unsigned int i
, idx
, shift
;
82 mutex_lock(&chip
->lock
);
83 for (i
= 0, bank
= chip
->registers
- 1; i
< chip
->registers
;
85 idx
= i
/ sizeof(*mask
);
86 shift
= i
% sizeof(*mask
) * BITS_PER_BYTE
;
87 bankmask
= mask
[idx
] >> shift
;
91 chip
->buffer
[bank
] &= ~bankmask
;
92 chip
->buffer
[bank
] |= bankmask
& (bits
[idx
] >> shift
);
94 __gen_74x164_write_config(chip
);
95 mutex_unlock(&chip
->lock
);
98 static int gen_74x164_direction_output(struct gpio_chip
*gc
,
99 unsigned offset
, int val
)
101 gen_74x164_set_value(gc
, offset
, val
);
105 static int gen_74x164_probe(struct spi_device
*spi
)
107 struct gen_74x164_chip
*chip
;
112 * bits_per_word cannot be configured in platform data
114 spi
->bits_per_word
= 8;
116 ret
= spi_setup(spi
);
120 if (of_property_read_u32(spi
->dev
.of_node
, "registers-number",
123 "Missing registers-number property in the DT.\n");
127 chip
= devm_kzalloc(&spi
->dev
, sizeof(*chip
) + nregs
, GFP_KERNEL
);
131 chip
->gpiod_oe
= devm_gpiod_get_optional(&spi
->dev
, "enable",
133 if (IS_ERR(chip
->gpiod_oe
))
134 return PTR_ERR(chip
->gpiod_oe
);
136 gpiod_set_value_cansleep(chip
->gpiod_oe
, 1);
138 spi_set_drvdata(spi
, chip
);
140 chip
->gpio_chip
.label
= spi
->modalias
;
141 chip
->gpio_chip
.direction_output
= gen_74x164_direction_output
;
142 chip
->gpio_chip
.get
= gen_74x164_get_value
;
143 chip
->gpio_chip
.set
= gen_74x164_set_value
;
144 chip
->gpio_chip
.set_multiple
= gen_74x164_set_multiple
;
145 chip
->gpio_chip
.base
= -1;
147 chip
->registers
= nregs
;
148 chip
->gpio_chip
.ngpio
= GEN_74X164_NUMBER_GPIOS
* chip
->registers
;
150 chip
->gpio_chip
.can_sleep
= true;
151 chip
->gpio_chip
.parent
= &spi
->dev
;
152 chip
->gpio_chip
.owner
= THIS_MODULE
;
154 mutex_init(&chip
->lock
);
156 ret
= __gen_74x164_write_config(chip
);
158 dev_err(&spi
->dev
, "Failed writing: %d\n", ret
);
162 ret
= gpiochip_add_data(&chip
->gpio_chip
, chip
);
167 mutex_destroy(&chip
->lock
);
172 static int gen_74x164_remove(struct spi_device
*spi
)
174 struct gen_74x164_chip
*chip
= spi_get_drvdata(spi
);
176 gpiod_set_value_cansleep(chip
->gpiod_oe
, 0);
177 gpiochip_remove(&chip
->gpio_chip
);
178 mutex_destroy(&chip
->lock
);
183 static const struct of_device_id gen_74x164_dt_ids
[] = {
184 { .compatible
= "fairchild,74hc595" },
185 { .compatible
= "nxp,74lvc594" },
188 MODULE_DEVICE_TABLE(of
, gen_74x164_dt_ids
);
190 static struct spi_driver gen_74x164_driver
= {
193 .of_match_table
= gen_74x164_dt_ids
,
195 .probe
= gen_74x164_probe
,
196 .remove
= gen_74x164_remove
,
198 module_spi_driver(gen_74x164_driver
);
200 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
201 MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.com>");
202 MODULE_DESCRIPTION("GPIO expander driver for 74X164 8-bits shift register");
203 MODULE_LICENSE("GPL v2");