2 * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com/
3 * Andrew F. Davis <afd@ti.com>
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.
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.
15 #include <linux/bitmap.h>
16 #include <linux/bitops.h>
17 #include <linux/delay.h>
18 #include <linux/gpio/consumer.h>
19 #include <linux/gpio/driver.h>
20 #include <linux/module.h>
21 #include <linux/mutex.h>
22 #include <linux/spi/spi.h>
24 #define DEFAULT_NGPIO 8
27 * struct pisosr_gpio - GPIO driver data
28 * @chip: GPIO controller chip
29 * @spi: SPI device pointer
30 * @buffer: Buffer for device reads
31 * @buffer_size: Size of buffer
32 * @load_gpio: GPIO pin used to load input into device
33 * @lock: Protects read sequences
36 struct gpio_chip chip
;
37 struct spi_device
*spi
;
40 struct gpio_desc
*load_gpio
;
44 static int pisosr_gpio_refresh(struct pisosr_gpio
*gpio
)
48 mutex_lock(&gpio
->lock
);
50 if (gpio
->load_gpio
) {
51 gpiod_set_value_cansleep(gpio
->load_gpio
, 1);
52 udelay(1); /* registers load time (~10ns) */
53 gpiod_set_value_cansleep(gpio
->load_gpio
, 0);
54 udelay(1); /* registers recovery time (~5ns) */
57 ret
= spi_read(gpio
->spi
, gpio
->buffer
, gpio
->buffer_size
);
59 mutex_unlock(&gpio
->lock
);
64 static int pisosr_gpio_get_direction(struct gpio_chip
*chip
,
67 /* This device always input */
68 return GPIO_LINE_DIRECTION_IN
;
71 static int pisosr_gpio_direction_input(struct gpio_chip
*chip
,
74 /* This device always input */
78 static int pisosr_gpio_direction_output(struct gpio_chip
*chip
,
79 unsigned offset
, int value
)
81 /* This device is input only */
85 static int pisosr_gpio_get(struct gpio_chip
*chip
, unsigned offset
)
87 struct pisosr_gpio
*gpio
= gpiochip_get_data(chip
);
89 /* Refresh may not always be needed */
90 pisosr_gpio_refresh(gpio
);
92 return (gpio
->buffer
[offset
/ 8] >> (offset
% 8)) & 0x1;
95 static int pisosr_gpio_get_multiple(struct gpio_chip
*chip
,
96 unsigned long *mask
, unsigned long *bits
)
98 struct pisosr_gpio
*gpio
= gpiochip_get_data(chip
);
100 unsigned long gpio_mask
;
101 unsigned long buffer_state
;
103 pisosr_gpio_refresh(gpio
);
105 bitmap_zero(bits
, chip
->ngpio
);
106 for_each_set_clump8(offset
, gpio_mask
, mask
, chip
->ngpio
) {
107 buffer_state
= gpio
->buffer
[offset
/ 8] & gpio_mask
;
108 bitmap_set_value8(bits
, buffer_state
, offset
);
114 static const struct gpio_chip template_chip
= {
115 .label
= "pisosr-gpio",
116 .owner
= THIS_MODULE
,
117 .get_direction
= pisosr_gpio_get_direction
,
118 .direction_input
= pisosr_gpio_direction_input
,
119 .direction_output
= pisosr_gpio_direction_output
,
120 .get
= pisosr_gpio_get
,
121 .get_multiple
= pisosr_gpio_get_multiple
,
123 .ngpio
= DEFAULT_NGPIO
,
127 static int pisosr_gpio_probe(struct spi_device
*spi
)
129 struct device
*dev
= &spi
->dev
;
130 struct pisosr_gpio
*gpio
;
133 gpio
= devm_kzalloc(dev
, sizeof(*gpio
), GFP_KERNEL
);
137 spi_set_drvdata(spi
, gpio
);
139 gpio
->chip
= template_chip
;
140 gpio
->chip
.parent
= dev
;
141 of_property_read_u16(dev
->of_node
, "ngpios", &gpio
->chip
.ngpio
);
145 gpio
->buffer_size
= DIV_ROUND_UP(gpio
->chip
.ngpio
, 8);
146 gpio
->buffer
= devm_kzalloc(dev
, gpio
->buffer_size
, GFP_KERNEL
);
150 gpio
->load_gpio
= devm_gpiod_get_optional(dev
, "load", GPIOD_OUT_LOW
);
151 if (IS_ERR(gpio
->load_gpio
))
152 return dev_err_probe(dev
, PTR_ERR(gpio
->load_gpio
),
153 "Unable to allocate load GPIO\n");
155 mutex_init(&gpio
->lock
);
157 ret
= gpiochip_add_data(&gpio
->chip
, gpio
);
159 dev_err(dev
, "Unable to register gpiochip\n");
166 static int pisosr_gpio_remove(struct spi_device
*spi
)
168 struct pisosr_gpio
*gpio
= spi_get_drvdata(spi
);
170 gpiochip_remove(&gpio
->chip
);
172 mutex_destroy(&gpio
->lock
);
177 static const struct spi_device_id pisosr_gpio_id_table
[] = {
181 MODULE_DEVICE_TABLE(spi
, pisosr_gpio_id_table
);
183 static const struct of_device_id pisosr_gpio_of_match_table
[] = {
184 { .compatible
= "pisosr-gpio", },
187 MODULE_DEVICE_TABLE(of
, pisosr_gpio_of_match_table
);
189 static struct spi_driver pisosr_gpio_driver
= {
191 .name
= "pisosr-gpio",
192 .of_match_table
= pisosr_gpio_of_match_table
,
194 .probe
= pisosr_gpio_probe
,
195 .remove
= pisosr_gpio_remove
,
196 .id_table
= pisosr_gpio_id_table
,
198 module_spi_driver(pisosr_gpio_driver
);
200 MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
201 MODULE_DESCRIPTION("SPI Compatible PISO Shift Register GPIO Driver");
202 MODULE_LICENSE("GPL v2");