1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Turris Mox Moxtet GPIO expander
4 *
5 * Copyright (C) 2018 Marek Behún <kabel@kernel.org>
6 */
7
8#include <linux/bitops.h>
9#include <linux/gpio/driver.h>
10#include <linux/moxtet.h>
11#include <linux/module.h>
12
13#define MOXTET_GPIO_NGPIOS 12
14#define MOXTET_GPIO_INPUTS 4
15
16struct moxtet_gpio_desc {
17 u16 in_mask;
18 u16 out_mask;
19};
20
21static const struct moxtet_gpio_desc descs[] = {
22 [TURRIS_MOX_MODULE_SFP] = {
23 .in_mask = GENMASK(2, 0),
24 .out_mask = GENMASK(5, 4),
25 },
26};
27
28struct moxtet_gpio_chip {
29 struct device *dev;
30 struct gpio_chip gpio_chip;
31 const struct moxtet_gpio_desc *desc;
32};
33
34static int moxtet_gpio_get_value(struct gpio_chip *gc, unsigned int offset)
35{
36 struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);
37 int ret;
38
39 if (chip->desc->in_mask & BIT(offset)) {
40 ret = moxtet_device_read(dev: chip->dev);
41 } else if (chip->desc->out_mask & BIT(offset)) {
42 ret = moxtet_device_written(dev: chip->dev);
43 if (ret >= 0)
44 ret <<= MOXTET_GPIO_INPUTS;
45 } else {
46 return -EINVAL;
47 }
48
49 if (ret < 0)
50 return ret;
51
52 return !!(ret & BIT(offset));
53}
54
55static void moxtet_gpio_set_value(struct gpio_chip *gc, unsigned int offset,
56 int val)
57{
58 struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);
59 int state;
60
61 state = moxtet_device_written(dev: chip->dev);
62 if (state < 0)
63 return;
64
65 offset -= MOXTET_GPIO_INPUTS;
66
67 if (val)
68 state |= BIT(offset);
69 else
70 state &= ~BIT(offset);
71
72 moxtet_device_write(dev: chip->dev, val: state);
73}
74
75static int moxtet_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
76{
77 struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);
78
79 /* All lines are hard wired to be either input or output, not both. */
80 if (chip->desc->in_mask & BIT(offset))
81 return GPIO_LINE_DIRECTION_IN;
82 else if (chip->desc->out_mask & BIT(offset))
83 return GPIO_LINE_DIRECTION_OUT;
84 else
85 return -EINVAL;
86}
87
88static int moxtet_gpio_direction_input(struct gpio_chip *gc,
89 unsigned int offset)
90{
91 struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);
92
93 if (chip->desc->in_mask & BIT(offset))
94 return 0;
95 else if (chip->desc->out_mask & BIT(offset))
96 return -ENOTSUPP;
97 else
98 return -EINVAL;
99}
100
101static int moxtet_gpio_direction_output(struct gpio_chip *gc,
102 unsigned int offset, int val)
103{
104 struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);
105
106 if (chip->desc->out_mask & BIT(offset))
107 moxtet_gpio_set_value(gc, offset, val);
108 else if (chip->desc->in_mask & BIT(offset))
109 return -ENOTSUPP;
110 else
111 return -EINVAL;
112
113 return 0;
114}
115
116static int moxtet_gpio_probe(struct device *dev)
117{
118 struct moxtet_gpio_chip *chip;
119 struct device_node *nc = dev->of_node;
120 int id;
121
122 id = to_moxtet_device(dev)->id;
123
124 if (id >= ARRAY_SIZE(descs)) {
125 dev_err(dev, "%pOF Moxtet device id 0x%x is not supported by gpio-moxtet driver\n",
126 nc, id);
127 return -ENOTSUPP;
128 }
129
130 chip = devm_kzalloc(dev, size: sizeof(*chip), GFP_KERNEL);
131 if (!chip)
132 return -ENOMEM;
133
134 chip->dev = dev;
135 chip->gpio_chip.parent = dev;
136 chip->desc = &descs[id];
137
138 dev_set_drvdata(dev, data: chip);
139
140 chip->gpio_chip.label = dev_name(dev);
141 chip->gpio_chip.get_direction = moxtet_gpio_get_direction;
142 chip->gpio_chip.direction_input = moxtet_gpio_direction_input;
143 chip->gpio_chip.direction_output = moxtet_gpio_direction_output;
144 chip->gpio_chip.get = moxtet_gpio_get_value;
145 chip->gpio_chip.set = moxtet_gpio_set_value;
146 chip->gpio_chip.base = -1;
147
148 chip->gpio_chip.ngpio = MOXTET_GPIO_NGPIOS;
149
150 chip->gpio_chip.can_sleep = true;
151 chip->gpio_chip.owner = THIS_MODULE;
152
153 return devm_gpiochip_add_data(dev, &chip->gpio_chip, chip);
154}
155
156static const struct of_device_id moxtet_gpio_dt_ids[] = {
157 { .compatible = "cznic,moxtet-gpio", },
158 {},
159};
160MODULE_DEVICE_TABLE(of, moxtet_gpio_dt_ids);
161
162static const enum turris_mox_module_id moxtet_gpio_module_table[] = {
163 TURRIS_MOX_MODULE_SFP,
164 0,
165};
166
167static struct moxtet_driver moxtet_gpio_driver = {
168 .driver = {
169 .name = "moxtet-gpio",
170 .of_match_table = moxtet_gpio_dt_ids,
171 .probe = moxtet_gpio_probe,
172 },
173 .id_table = moxtet_gpio_module_table,
174};
175module_moxtet_driver(moxtet_gpio_driver);
176
177MODULE_AUTHOR("Marek Behun <kabel@kernel.org>");
178MODULE_DESCRIPTION("Turris Mox Moxtet GPIO expander");
179MODULE_LICENSE("GPL v2");
180

source code of linux/drivers/gpio/gpio-moxtet.c