1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  74Hx164 - Generic serial-in/parallel-out 8-bits shift register GPIO driver
4  *
5  *  Copyright (C) 2010 Gabor Juhos <juhosg@openwrt.org>
6  *  Copyright (C) 2010 Miguel Gaio <miguel.gaio@efixo.com>
7  */
8 
9 #include <linux/bitops.h>
10 #include <linux/gpio/consumer.h>
11 #include <linux/gpio/driver.h>
12 #include <linux/module.h>
13 #include <linux/mutex.h>
14 #include <linux/property.h>
15 #include <linux/slab.h>
16 #include <linux/spi/spi.h>
17 
18 #define GEN_74X164_NUMBER_GPIOS	8
19 
20 struct gen_74x164_chip {
21 	struct gpio_chip	gpio_chip;
22 	struct mutex		lock;
23 	struct gpio_desc	*gpiod_oe;
24 	u32			registers;
25 	/*
26 	 * Since the registers are chained, every byte sent will make
27 	 * the previous byte shift to the next register in the
28 	 * chain. Thus, the first byte sent will end up in the last
29 	 * register at the end of the transfer. So, to have a logical
30 	 * numbering, store the bytes in reverse order.
31 	 */
32 	u8			buffer[];
33 };
34 
__gen_74x164_write_config(struct gen_74x164_chip * chip)35 static int __gen_74x164_write_config(struct gen_74x164_chip *chip)
36 {
37 	return spi_write(to_spi_device(chip->gpio_chip.parent), chip->buffer,
38 			 chip->registers);
39 }
40 
gen_74x164_get_value(struct gpio_chip * gc,unsigned offset)41 static int gen_74x164_get_value(struct gpio_chip *gc, unsigned offset)
42 {
43 	struct gen_74x164_chip *chip = gpiochip_get_data(gc);
44 	u8 bank = chip->registers - 1 - offset / 8;
45 	u8 pin = offset % 8;
46 	int ret;
47 
48 	mutex_lock(&chip->lock);
49 	ret = (chip->buffer[bank] >> pin) & 0x1;
50 	mutex_unlock(&chip->lock);
51 
52 	return ret;
53 }
54 
gen_74x164_set_value(struct gpio_chip * gc,unsigned offset,int val)55 static void gen_74x164_set_value(struct gpio_chip *gc,
56 		unsigned offset, int val)
57 {
58 	struct gen_74x164_chip *chip = gpiochip_get_data(gc);
59 	u8 bank = chip->registers - 1 - offset / 8;
60 	u8 pin = offset % 8;
61 
62 	mutex_lock(&chip->lock);
63 	if (val)
64 		chip->buffer[bank] |= (1 << pin);
65 	else
66 		chip->buffer[bank] &= ~(1 << pin);
67 
68 	__gen_74x164_write_config(chip);
69 	mutex_unlock(&chip->lock);
70 }
71 
gen_74x164_set_multiple(struct gpio_chip * gc,unsigned long * mask,unsigned long * bits)72 static void gen_74x164_set_multiple(struct gpio_chip *gc, unsigned long *mask,
73 				    unsigned long *bits)
74 {
75 	struct gen_74x164_chip *chip = gpiochip_get_data(gc);
76 	unsigned long offset;
77 	unsigned long bankmask;
78 	size_t bank;
79 	unsigned long bitmask;
80 
81 	mutex_lock(&chip->lock);
82 	for_each_set_clump8(offset, bankmask, mask, chip->registers * 8) {
83 		bank = chip->registers - 1 - offset / 8;
84 		bitmask = bitmap_get_value8(bits, offset) & bankmask;
85 
86 		chip->buffer[bank] &= ~bankmask;
87 		chip->buffer[bank] |= bitmask;
88 	}
89 	__gen_74x164_write_config(chip);
90 	mutex_unlock(&chip->lock);
91 }
92 
gen_74x164_direction_output(struct gpio_chip * gc,unsigned offset,int val)93 static int gen_74x164_direction_output(struct gpio_chip *gc,
94 		unsigned offset, int val)
95 {
96 	gen_74x164_set_value(gc, offset, val);
97 	return 0;
98 }
99 
gen_74x164_probe(struct spi_device * spi)100 static int gen_74x164_probe(struct spi_device *spi)
101 {
102 	struct gen_74x164_chip *chip;
103 	u32 nregs;
104 	int ret;
105 
106 	/*
107 	 * bits_per_word cannot be configured in platform data
108 	 */
109 	spi->bits_per_word = 8;
110 
111 	ret = spi_setup(spi);
112 	if (ret < 0)
113 		return ret;
114 
115 	ret = device_property_read_u32(&spi->dev, "registers-number", &nregs);
116 	if (ret) {
117 		dev_err(&spi->dev, "Missing 'registers-number' property.\n");
118 		return -EINVAL;
119 	}
120 
121 	chip = devm_kzalloc(&spi->dev, sizeof(*chip) + nregs, GFP_KERNEL);
122 	if (!chip)
123 		return -ENOMEM;
124 
125 	chip->gpiod_oe = devm_gpiod_get_optional(&spi->dev, "enable",
126 						 GPIOD_OUT_LOW);
127 	if (IS_ERR(chip->gpiod_oe))
128 		return PTR_ERR(chip->gpiod_oe);
129 
130 	gpiod_set_value_cansleep(chip->gpiod_oe, 1);
131 
132 	spi_set_drvdata(spi, chip);
133 
134 	chip->gpio_chip.label = spi->modalias;
135 	chip->gpio_chip.direction_output = gen_74x164_direction_output;
136 	chip->gpio_chip.get = gen_74x164_get_value;
137 	chip->gpio_chip.set = gen_74x164_set_value;
138 	chip->gpio_chip.set_multiple = gen_74x164_set_multiple;
139 	chip->gpio_chip.base = -1;
140 
141 	chip->registers = nregs;
142 	chip->gpio_chip.ngpio = GEN_74X164_NUMBER_GPIOS * chip->registers;
143 
144 	chip->gpio_chip.can_sleep = true;
145 	chip->gpio_chip.parent = &spi->dev;
146 	chip->gpio_chip.owner = THIS_MODULE;
147 
148 	mutex_init(&chip->lock);
149 
150 	ret = __gen_74x164_write_config(chip);
151 	if (ret) {
152 		dev_err(&spi->dev, "Failed writing: %d\n", ret);
153 		goto exit_destroy;
154 	}
155 
156 	ret = gpiochip_add_data(&chip->gpio_chip, chip);
157 	if (!ret)
158 		return 0;
159 
160 exit_destroy:
161 	mutex_destroy(&chip->lock);
162 
163 	return ret;
164 }
165 
gen_74x164_remove(struct spi_device * spi)166 static void gen_74x164_remove(struct spi_device *spi)
167 {
168 	struct gen_74x164_chip *chip = spi_get_drvdata(spi);
169 
170 	gpiod_set_value_cansleep(chip->gpiod_oe, 0);
171 	gpiochip_remove(&chip->gpio_chip);
172 	mutex_destroy(&chip->lock);
173 }
174 
175 static const struct spi_device_id gen_74x164_spi_ids[] = {
176 	{ .name = "74hc595" },
177 	{ .name = "74lvc594" },
178 	{},
179 };
180 MODULE_DEVICE_TABLE(spi, gen_74x164_spi_ids);
181 
182 static const struct of_device_id gen_74x164_dt_ids[] = {
183 	{ .compatible = "fairchild,74hc595" },
184 	{ .compatible = "nxp,74lvc594" },
185 	{},
186 };
187 MODULE_DEVICE_TABLE(of, gen_74x164_dt_ids);
188 
189 static struct spi_driver gen_74x164_driver = {
190 	.driver = {
191 		.name		= "74x164",
192 		.of_match_table	= gen_74x164_dt_ids,
193 	},
194 	.probe		= gen_74x164_probe,
195 	.remove		= gen_74x164_remove,
196 	.id_table	= gen_74x164_spi_ids,
197 };
198 module_spi_driver(gen_74x164_driver);
199 
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");
204