1/*
  2 *  SYSCON GPIO driver
  3 *
  4 *  Copyright (C) 2014 Alexander Shiyan <shc_work@mail.ru>
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License as published by
  8 * the Free Software Foundation; either version 2 of the License, or
  9 * (at your option) any later version.
 10 */
 11
 12#include <linux/err.h>
 13#include <linux/gpio.h>
 14#include <linux/module.h>
 15#include <linux/of.h>
 16#include <linux/of_device.h>
 17#include <linux/platform_device.h>
 18#include <linux/regmap.h>
 19#include <linux/mfd/syscon.h>
 20
 21#define GPIO_SYSCON_FEAT_IN	BIT(0)
 22#define GPIO_SYSCON_FEAT_OUT	BIT(1)
 23#define GPIO_SYSCON_FEAT_DIR	BIT(2)
 24
 25/* SYSCON driver is designed to use 32-bit wide registers */
 26#define SYSCON_REG_SIZE		(4)
 27#define SYSCON_REG_BITS		(SYSCON_REG_SIZE * 8)
 28
 29/**
 30 * struct syscon_gpio_data - Configuration for the device.
 31 * compatible:		SYSCON driver compatible string.
 32 * flags:		Set of GPIO_SYSCON_FEAT_ flags:
 33 *			GPIO_SYSCON_FEAT_IN:	GPIOs supports input,
 34 *			GPIO_SYSCON_FEAT_OUT:	GPIOs supports output,
 35 *			GPIO_SYSCON_FEAT_DIR:	GPIOs supports switch direction.
 36 * bit_count:		Number of bits used as GPIOs.
 37 * dat_bit_offset:	Offset (in bits) to the first GPIO bit.
 38 * dir_bit_offset:	Optional offset (in bits) to the first bit to switch
 39 *			GPIO direction (Used with GPIO_SYSCON_FEAT_DIR flag).
 40 */
 41
 42struct syscon_gpio_data {
 43	const char	*compatible;
 44	unsigned int	flags;
 45	unsigned int	bit_count;
 46	unsigned int	dat_bit_offset;
 47	unsigned int	dir_bit_offset;
 48};
 49
 50struct syscon_gpio_priv {
 51	struct gpio_chip		chip;
 52	struct regmap			*syscon;
 53	const struct syscon_gpio_data	*data;
 54};
 55
 56static inline struct syscon_gpio_priv *to_syscon_gpio(struct gpio_chip *chip)
 57{
 58	return container_of(chip, struct syscon_gpio_priv, chip);
 59}
 60
 61static int syscon_gpio_get(struct gpio_chip *chip, unsigned offset)
 62{
 63	struct syscon_gpio_priv *priv = to_syscon_gpio(chip);
 64	unsigned int val, offs = priv->data->dat_bit_offset + offset;
 65	int ret;
 66
 67	ret = regmap_read(priv->syscon,
 68			  (offs / SYSCON_REG_BITS) * SYSCON_REG_SIZE, &val);
 69	if (ret)
 70		return ret;
 71
 72	return !!(val & BIT(offs % SYSCON_REG_BITS));
 73}
 74
 75static void syscon_gpio_set(struct gpio_chip *chip, unsigned offset, int val)
 76{
 77	struct syscon_gpio_priv *priv = to_syscon_gpio(chip);
 78	unsigned int offs = priv->data->dat_bit_offset + offset;
 79
 80	regmap_update_bits(priv->syscon,
 81			   (offs / SYSCON_REG_BITS) * SYSCON_REG_SIZE,
 82			   BIT(offs % SYSCON_REG_BITS),
 83			   val ? BIT(offs % SYSCON_REG_BITS) : 0);
 84}
 85
 86static int syscon_gpio_dir_in(struct gpio_chip *chip, unsigned offset)
 87{
 88	struct syscon_gpio_priv *priv = to_syscon_gpio(chip);
 89
 90	if (priv->data->flags & GPIO_SYSCON_FEAT_DIR) {
 91		unsigned int offs = priv->data->dir_bit_offset + offset;
 92
 93		regmap_update_bits(priv->syscon,
 94				   (offs / SYSCON_REG_BITS) * SYSCON_REG_SIZE,
 95				   BIT(offs % SYSCON_REG_BITS), 0);
 96	}
 97
 98	return 0;
 99}
100
101static int syscon_gpio_dir_out(struct gpio_chip *chip, unsigned offset, int val)
102{
103	struct syscon_gpio_priv *priv = to_syscon_gpio(chip);
104
105	if (priv->data->flags & GPIO_SYSCON_FEAT_DIR) {
106		unsigned int offs = priv->data->dir_bit_offset + offset;
107
108		regmap_update_bits(priv->syscon,
109				   (offs / SYSCON_REG_BITS) * SYSCON_REG_SIZE,
110				   BIT(offs % SYSCON_REG_BITS),
111				   BIT(offs % SYSCON_REG_BITS));
112	}
113
114	syscon_gpio_set(chip, offset, val);
115
116	return 0;
117}
118
119static const struct syscon_gpio_data clps711x_mctrl_gpio = {
120	/* ARM CLPS711X SYSFLG1 Bits 8-10 */
121	.compatible	= "cirrus,clps711x-syscon1",
122	.flags		= GPIO_SYSCON_FEAT_IN,
123	.bit_count	= 3,
124	.dat_bit_offset	= 0x40 * 8 + 8,
125};
126
127static const struct of_device_id syscon_gpio_ids[] = {
128	{
129		.compatible	= "cirrus,clps711x-mctrl-gpio",
130		.data		= &clps711x_mctrl_gpio,
131	},
132	{ }
133};
134MODULE_DEVICE_TABLE(of, syscon_gpio_ids);
135
136static int syscon_gpio_probe(struct platform_device *pdev)
137{
138	struct device *dev = &pdev->dev;
139	const struct of_device_id *of_id = of_match_device(syscon_gpio_ids, dev);
140	struct syscon_gpio_priv *priv;
141
142	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
143	if (!priv)
144		return -ENOMEM;
145
146	priv->data = of_id->data;
147
148	priv->syscon =
149		syscon_regmap_lookup_by_compatible(priv->data->compatible);
150	if (IS_ERR(priv->syscon))
151		return PTR_ERR(priv->syscon);
152
153	priv->chip.dev = dev;
154	priv->chip.owner = THIS_MODULE;
155	priv->chip.label = dev_name(dev);
156	priv->chip.base = -1;
157	priv->chip.ngpio = priv->data->bit_count;
158	priv->chip.get = syscon_gpio_get;
159	if (priv->data->flags & GPIO_SYSCON_FEAT_IN)
160		priv->chip.direction_input = syscon_gpio_dir_in;
161	if (priv->data->flags & GPIO_SYSCON_FEAT_OUT) {
162		priv->chip.set = syscon_gpio_set;
163		priv->chip.direction_output = syscon_gpio_dir_out;
164	}
165
166	platform_set_drvdata(pdev, priv);
167
168	return gpiochip_add(&priv->chip);
169}
170
171static int syscon_gpio_remove(struct platform_device *pdev)
172{
173	struct syscon_gpio_priv *priv = platform_get_drvdata(pdev);
174
175	return gpiochip_remove(&priv->chip);
176}
177
178static struct platform_driver syscon_gpio_driver = {
179	.driver	= {
180		.name		= "gpio-syscon",
181		.owner		= THIS_MODULE,
182		.of_match_table	= syscon_gpio_ids,
183	},
184	.probe	= syscon_gpio_probe,
185	.remove	= syscon_gpio_remove,
186};
187module_platform_driver(syscon_gpio_driver);
188
189MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
190MODULE_DESCRIPTION("SYSCON GPIO driver");
191MODULE_LICENSE("GPL");