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(chip->dev);
 41	} else if (chip->desc->out_mask & BIT(offset)) {
 42		ret = moxtet_device_written(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(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(chip->dev, 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, 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, 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");