xref: /linux/drivers/gpio/gpio-pisosr.c (revision a1c613ae4c322ddd58d5a8539dbfba2a0380a8c0)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2015-2023 Texas Instruments Incorporated - https://www.ti.com/
4  *	Andrew Davis <afd@ti.com>
5  */
6 
7 #include <linux/bitmap.h>
8 #include <linux/bitops.h>
9 #include <linux/delay.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/spi/spi.h>
15 
16 #define DEFAULT_NGPIO 8
17 
18 /**
19  * struct pisosr_gpio - GPIO driver data
20  * @chip: GPIO controller chip
21  * @spi: SPI device pointer
22  * @buffer: Buffer for device reads
23  * @buffer_size: Size of buffer
24  * @load_gpio: GPIO pin used to load input into device
25  * @lock: Protects read sequences
26  */
27 struct pisosr_gpio {
28 	struct gpio_chip chip;
29 	struct spi_device *spi;
30 	u8 *buffer;
31 	size_t buffer_size;
32 	struct gpio_desc *load_gpio;
33 	struct mutex lock;
34 };
35 
pisosr_gpio_refresh(struct pisosr_gpio * gpio)36 static int pisosr_gpio_refresh(struct pisosr_gpio *gpio)
37 {
38 	int ret;
39 
40 	mutex_lock(&gpio->lock);
41 
42 	if (gpio->load_gpio) {
43 		gpiod_set_value_cansleep(gpio->load_gpio, 1);
44 		udelay(1); /* registers load time (~10ns) */
45 		gpiod_set_value_cansleep(gpio->load_gpio, 0);
46 		udelay(1); /* registers recovery time (~5ns) */
47 	}
48 
49 	ret = spi_read(gpio->spi, gpio->buffer, gpio->buffer_size);
50 
51 	mutex_unlock(&gpio->lock);
52 
53 	return ret;
54 }
55 
pisosr_gpio_get_direction(struct gpio_chip * chip,unsigned offset)56 static int pisosr_gpio_get_direction(struct gpio_chip *chip,
57 				     unsigned offset)
58 {
59 	/* This device always input */
60 	return GPIO_LINE_DIRECTION_IN;
61 }
62 
pisosr_gpio_direction_input(struct gpio_chip * chip,unsigned offset)63 static int pisosr_gpio_direction_input(struct gpio_chip *chip,
64 				       unsigned offset)
65 {
66 	/* This device always input */
67 	return 0;
68 }
69 
pisosr_gpio_direction_output(struct gpio_chip * chip,unsigned offset,int value)70 static int pisosr_gpio_direction_output(struct gpio_chip *chip,
71 					unsigned offset, int value)
72 {
73 	/* This device is input only */
74 	return -EINVAL;
75 }
76 
pisosr_gpio_get(struct gpio_chip * chip,unsigned offset)77 static int pisosr_gpio_get(struct gpio_chip *chip, unsigned offset)
78 {
79 	struct pisosr_gpio *gpio = gpiochip_get_data(chip);
80 
81 	/* Refresh may not always be needed */
82 	pisosr_gpio_refresh(gpio);
83 
84 	return (gpio->buffer[offset / 8] >> (offset % 8)) & 0x1;
85 }
86 
pisosr_gpio_get_multiple(struct gpio_chip * chip,unsigned long * mask,unsigned long * bits)87 static int pisosr_gpio_get_multiple(struct gpio_chip *chip,
88 				    unsigned long *mask, unsigned long *bits)
89 {
90 	struct pisosr_gpio *gpio = gpiochip_get_data(chip);
91 	unsigned long offset;
92 	unsigned long gpio_mask;
93 	unsigned long buffer_state;
94 
95 	pisosr_gpio_refresh(gpio);
96 
97 	bitmap_zero(bits, chip->ngpio);
98 	for_each_set_clump8(offset, gpio_mask, mask, chip->ngpio) {
99 		buffer_state = gpio->buffer[offset / 8] & gpio_mask;
100 		bitmap_set_value8(bits, buffer_state, offset);
101 	}
102 
103 	return 0;
104 }
105 
106 static const struct gpio_chip template_chip = {
107 	.label			= "pisosr-gpio",
108 	.owner			= THIS_MODULE,
109 	.get_direction		= pisosr_gpio_get_direction,
110 	.direction_input	= pisosr_gpio_direction_input,
111 	.direction_output	= pisosr_gpio_direction_output,
112 	.get			= pisosr_gpio_get,
113 	.get_multiple		= pisosr_gpio_get_multiple,
114 	.base			= -1,
115 	.ngpio			= DEFAULT_NGPIO,
116 	.can_sleep		= true,
117 };
118 
pisosr_mutex_destroy(void * lock)119 static void pisosr_mutex_destroy(void *lock)
120 {
121 	mutex_destroy(lock);
122 }
123 
pisosr_gpio_probe(struct spi_device * spi)124 static int pisosr_gpio_probe(struct spi_device *spi)
125 {
126 	struct device *dev = &spi->dev;
127 	struct pisosr_gpio *gpio;
128 	int ret;
129 
130 	gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL);
131 	if (!gpio)
132 		return -ENOMEM;
133 
134 	gpio->chip = template_chip;
135 	gpio->chip.parent = dev;
136 	of_property_read_u16(dev->of_node, "ngpios", &gpio->chip.ngpio);
137 
138 	gpio->spi = spi;
139 
140 	gpio->buffer_size = DIV_ROUND_UP(gpio->chip.ngpio, 8);
141 	gpio->buffer = devm_kzalloc(dev, gpio->buffer_size, GFP_KERNEL);
142 	if (!gpio->buffer)
143 		return -ENOMEM;
144 
145 	gpio->load_gpio = devm_gpiod_get_optional(dev, "load", GPIOD_OUT_LOW);
146 	if (IS_ERR(gpio->load_gpio))
147 		return dev_err_probe(dev, PTR_ERR(gpio->load_gpio),
148 				     "Unable to allocate load GPIO\n");
149 
150 	mutex_init(&gpio->lock);
151 	ret = devm_add_action_or_reset(dev, pisosr_mutex_destroy, &gpio->lock);
152 	if (ret)
153 		return ret;
154 
155 	ret = devm_gpiochip_add_data(dev, &gpio->chip, gpio);
156 	if (ret < 0) {
157 		dev_err(dev, "Unable to register gpiochip\n");
158 		return ret;
159 	}
160 
161 	return 0;
162 }
163 
164 static const struct spi_device_id pisosr_gpio_id_table[] = {
165 	{ "pisosr-gpio", },
166 	{ /* sentinel */ }
167 };
168 MODULE_DEVICE_TABLE(spi, pisosr_gpio_id_table);
169 
170 static const struct of_device_id pisosr_gpio_of_match_table[] = {
171 	{ .compatible = "pisosr-gpio", },
172 	{ /* sentinel */ }
173 };
174 MODULE_DEVICE_TABLE(of, pisosr_gpio_of_match_table);
175 
176 static struct spi_driver pisosr_gpio_driver = {
177 	.driver = {
178 		.name = "pisosr-gpio",
179 		.of_match_table = pisosr_gpio_of_match_table,
180 	},
181 	.probe = pisosr_gpio_probe,
182 	.id_table = pisosr_gpio_id_table,
183 };
184 module_spi_driver(pisosr_gpio_driver);
185 
186 MODULE_AUTHOR("Andrew Davis <afd@ti.com>");
187 MODULE_DESCRIPTION("SPI Compatible PISO Shift Register GPIO Driver");
188 MODULE_LICENSE("GPL v2");
189