Loading...
1/*
2 * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com/
3 * Andrew F. Davis <afd@ti.com>
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 *
9 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
10 * kind, whether expressed or implied; without even the implied warranty
11 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License version 2 for more details.
13 */
14
15#include <linux/delay.h>
16#include <linux/gpio/consumer.h>
17#include <linux/gpio/driver.h>
18#include <linux/module.h>
19#include <linux/mutex.h>
20#include <linux/spi/spi.h>
21
22#define DEFAULT_NGPIO 8
23
24/**
25 * struct pisosr_gpio - GPIO driver data
26 * @chip: GPIO controller chip
27 * @spi: SPI device pointer
28 * @buffer: Buffer for device reads
29 * @buffer_size: Size of buffer
30 * @load_gpio: GPIO pin used to load input into device
31 * @lock: Protects read sequences
32 */
33struct pisosr_gpio {
34 struct gpio_chip chip;
35 struct spi_device *spi;
36 u8 *buffer;
37 size_t buffer_size;
38 struct gpio_desc *load_gpio;
39 struct mutex lock;
40};
41
42static int pisosr_gpio_refresh(struct pisosr_gpio *gpio)
43{
44 int ret;
45
46 mutex_lock(&gpio->lock);
47
48 if (gpio->load_gpio) {
49 gpiod_set_value_cansleep(gpio->load_gpio, 1);
50 udelay(1); /* registers load time (~10ns) */
51 gpiod_set_value_cansleep(gpio->load_gpio, 0);
52 udelay(1); /* registers recovery time (~5ns) */
53 }
54
55 ret = spi_read(gpio->spi, gpio->buffer, gpio->buffer_size);
56
57 mutex_unlock(&gpio->lock);
58
59 return ret;
60}
61
62static int pisosr_gpio_get_direction(struct gpio_chip *chip,
63 unsigned offset)
64{
65 /* This device always input */
66 return 1;
67}
68
69static int pisosr_gpio_direction_input(struct gpio_chip *chip,
70 unsigned offset)
71{
72 /* This device always input */
73 return 0;
74}
75
76static int pisosr_gpio_direction_output(struct gpio_chip *chip,
77 unsigned offset, int value)
78{
79 /* This device is input only */
80 return -EINVAL;
81}
82
83static int pisosr_gpio_get(struct gpio_chip *chip, unsigned offset)
84{
85 struct pisosr_gpio *gpio = gpiochip_get_data(chip);
86
87 /* Refresh may not always be needed */
88 pisosr_gpio_refresh(gpio);
89
90 return (gpio->buffer[offset / 8] >> (offset % 8)) & 0x1;
91}
92
93static struct gpio_chip template_chip = {
94 .label = "pisosr-gpio",
95 .owner = THIS_MODULE,
96 .get_direction = pisosr_gpio_get_direction,
97 .direction_input = pisosr_gpio_direction_input,
98 .direction_output = pisosr_gpio_direction_output,
99 .get = pisosr_gpio_get,
100 .base = -1,
101 .ngpio = DEFAULT_NGPIO,
102 .can_sleep = true,
103};
104
105static int pisosr_gpio_probe(struct spi_device *spi)
106{
107 struct device *dev = &spi->dev;
108 struct pisosr_gpio *gpio;
109 int ret;
110
111 gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL);
112 if (!gpio)
113 return -ENOMEM;
114
115 spi_set_drvdata(spi, gpio);
116
117 gpio->chip = template_chip;
118 gpio->chip.parent = dev;
119 of_property_read_u16(dev->of_node, "ngpios", &gpio->chip.ngpio);
120
121 gpio->spi = spi;
122
123 gpio->buffer_size = DIV_ROUND_UP(gpio->chip.ngpio, 8);
124 gpio->buffer = devm_kzalloc(dev, gpio->buffer_size, GFP_KERNEL);
125 if (!gpio->buffer)
126 return -ENOMEM;
127
128 gpio->load_gpio = devm_gpiod_get_optional(dev, "load", GPIOD_OUT_LOW);
129 if (IS_ERR(gpio->load_gpio)) {
130 ret = PTR_ERR(gpio->load_gpio);
131 if (ret != -EPROBE_DEFER)
132 dev_err(dev, "Unable to allocate load GPIO\n");
133 return ret;
134 }
135
136 mutex_init(&gpio->lock);
137
138 ret = gpiochip_add_data(&gpio->chip, gpio);
139 if (ret < 0) {
140 dev_err(dev, "Unable to register gpiochip\n");
141 return ret;
142 }
143
144 return 0;
145}
146
147static int pisosr_gpio_remove(struct spi_device *spi)
148{
149 struct pisosr_gpio *gpio = spi_get_drvdata(spi);
150
151 gpiochip_remove(&gpio->chip);
152
153 mutex_destroy(&gpio->lock);
154
155 return 0;
156}
157
158static const struct spi_device_id pisosr_gpio_id_table[] = {
159 { "pisosr-gpio", },
160 { /* sentinel */ }
161};
162MODULE_DEVICE_TABLE(spi, pisosr_gpio_id_table);
163
164static const struct of_device_id pisosr_gpio_of_match_table[] = {
165 { .compatible = "pisosr-gpio", },
166 { /* sentinel */ }
167};
168MODULE_DEVICE_TABLE(of, pisosr_gpio_of_match_table);
169
170static struct spi_driver pisosr_gpio_driver = {
171 .driver = {
172 .name = "pisosr-gpio",
173 .of_match_table = pisosr_gpio_of_match_table,
174 },
175 .probe = pisosr_gpio_probe,
176 .remove = pisosr_gpio_remove,
177 .id_table = pisosr_gpio_id_table,
178};
179module_spi_driver(pisosr_gpio_driver);
180
181MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
182MODULE_DESCRIPTION("SPI Compatible PISO Shift Register GPIO Driver");
183MODULE_LICENSE("GPL v2");
1/*
2 * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com/
3 * Andrew F. Davis <afd@ti.com>
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 *
9 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
10 * kind, whether expressed or implied; without even the implied warranty
11 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License version 2 for more details.
13 */
14
15#include <linux/delay.h>
16#include <linux/gpio/consumer.h>
17#include <linux/gpio/driver.h>
18#include <linux/module.h>
19#include <linux/mutex.h>
20#include <linux/spi/spi.h>
21
22#define DEFAULT_NGPIO 8
23
24/**
25 * struct pisosr_gpio - GPIO driver data
26 * @chip: GPIO controller chip
27 * @spi: SPI device pointer
28 * @buffer: Buffer for device reads
29 * @buffer_size: Size of buffer
30 * @load_gpio: GPIO pin used to load input into device
31 * @lock: Protects read sequences
32 */
33struct pisosr_gpio {
34 struct gpio_chip chip;
35 struct spi_device *spi;
36 u8 *buffer;
37 size_t buffer_size;
38 struct gpio_desc *load_gpio;
39 struct mutex lock;
40};
41
42static int pisosr_gpio_refresh(struct pisosr_gpio *gpio)
43{
44 int ret;
45
46 mutex_lock(&gpio->lock);
47
48 if (gpio->load_gpio) {
49 gpiod_set_value_cansleep(gpio->load_gpio, 1);
50 udelay(1); /* registers load time (~10ns) */
51 gpiod_set_value_cansleep(gpio->load_gpio, 0);
52 udelay(1); /* registers recovery time (~5ns) */
53 }
54
55 ret = spi_read(gpio->spi, gpio->buffer, gpio->buffer_size);
56
57 mutex_unlock(&gpio->lock);
58
59 return ret;
60}
61
62static int pisosr_gpio_get_direction(struct gpio_chip *chip,
63 unsigned offset)
64{
65 /* This device always input */
66 return 1;
67}
68
69static int pisosr_gpio_direction_input(struct gpio_chip *chip,
70 unsigned offset)
71{
72 /* This device always input */
73 return 0;
74}
75
76static int pisosr_gpio_direction_output(struct gpio_chip *chip,
77 unsigned offset, int value)
78{
79 /* This device is input only */
80 return -EINVAL;
81}
82
83static int pisosr_gpio_get(struct gpio_chip *chip, unsigned offset)
84{
85 struct pisosr_gpio *gpio = gpiochip_get_data(chip);
86
87 /* Refresh may not always be needed */
88 pisosr_gpio_refresh(gpio);
89
90 return (gpio->buffer[offset / 8] >> (offset % 8)) & 0x1;
91}
92
93static struct gpio_chip template_chip = {
94 .label = "pisosr-gpio",
95 .owner = THIS_MODULE,
96 .get_direction = pisosr_gpio_get_direction,
97 .direction_input = pisosr_gpio_direction_input,
98 .direction_output = pisosr_gpio_direction_output,
99 .get = pisosr_gpio_get,
100 .base = -1,
101 .ngpio = DEFAULT_NGPIO,
102 .can_sleep = true,
103};
104
105static int pisosr_gpio_probe(struct spi_device *spi)
106{
107 struct device *dev = &spi->dev;
108 struct pisosr_gpio *gpio;
109 int ret;
110
111 gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL);
112 if (!gpio)
113 return -ENOMEM;
114
115 spi_set_drvdata(spi, gpio);
116
117 gpio->chip = template_chip;
118 gpio->chip.parent = dev;
119 of_property_read_u16(dev->of_node, "ngpios", &gpio->chip.ngpio);
120
121 gpio->spi = spi;
122
123 gpio->buffer_size = DIV_ROUND_UP(gpio->chip.ngpio, 8);
124 gpio->buffer = devm_kzalloc(dev, gpio->buffer_size, GFP_KERNEL);
125 if (!gpio->buffer)
126 return -ENOMEM;
127
128 gpio->load_gpio = devm_gpiod_get_optional(dev, "load", GPIOD_OUT_LOW);
129 if (IS_ERR(gpio->load_gpio)) {
130 ret = PTR_ERR(gpio->load_gpio);
131 if (ret != -EPROBE_DEFER)
132 dev_err(dev, "Unable to allocate load GPIO\n");
133 return ret;
134 }
135
136 mutex_init(&gpio->lock);
137
138 ret = gpiochip_add_data(&gpio->chip, gpio);
139 if (ret < 0) {
140 dev_err(dev, "Unable to register gpiochip\n");
141 return ret;
142 }
143
144 return 0;
145}
146
147static int pisosr_gpio_remove(struct spi_device *spi)
148{
149 struct pisosr_gpio *gpio = spi_get_drvdata(spi);
150
151 gpiochip_remove(&gpio->chip);
152
153 mutex_destroy(&gpio->lock);
154
155 return 0;
156}
157
158static const struct spi_device_id pisosr_gpio_id_table[] = {
159 { "pisosr-gpio", },
160 { /* sentinel */ }
161};
162MODULE_DEVICE_TABLE(spi, pisosr_gpio_id_table);
163
164static const struct of_device_id pisosr_gpio_of_match_table[] = {
165 { .compatible = "pisosr-gpio", },
166 { /* sentinel */ }
167};
168MODULE_DEVICE_TABLE(of, pisosr_gpio_of_match_table);
169
170static struct spi_driver pisosr_gpio_driver = {
171 .driver = {
172 .name = "pisosr-gpio",
173 .of_match_table = pisosr_gpio_of_match_table,
174 },
175 .probe = pisosr_gpio_probe,
176 .remove = pisosr_gpio_remove,
177 .id_table = pisosr_gpio_id_table,
178};
179module_spi_driver(pisosr_gpio_driver);
180
181MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
182MODULE_DESCRIPTION("SPI Compatible PISO Shift Register GPIO Driver");
183MODULE_LICENSE("GPL v2");