1/*
  2 * TI/National Semiconductor LP3943 GPIO driver
  3 *
  4 * Copyright 2013 Texas Instruments
  5 *
  6 * Author: Milo Kim <milo.kim@ti.com>
  7 *
  8 * This program is free software; you can redistribute it and/or modify
  9 * it under the terms of the GNU General Public License as published by
 10 * the Free Software Foundation; version 2.
 11 */
 12
 13#include <linux/bitops.h>
 14#include <linux/err.h>
 15#include <linux/gpio.h>
 16#include <linux/i2c.h>
 17#include <linux/mfd/lp3943.h>
 18#include <linux/module.h>
 19#include <linux/platform_device.h>
 20#include <linux/slab.h>
 21
 22enum lp3943_gpios {
 23	LP3943_GPIO1,
 24	LP3943_GPIO2,
 25	LP3943_GPIO3,
 26	LP3943_GPIO4,
 27	LP3943_GPIO5,
 28	LP3943_GPIO6,
 29	LP3943_GPIO7,
 30	LP3943_GPIO8,
 31	LP3943_GPIO9,
 32	LP3943_GPIO10,
 33	LP3943_GPIO11,
 34	LP3943_GPIO12,
 35	LP3943_GPIO13,
 36	LP3943_GPIO14,
 37	LP3943_GPIO15,
 38	LP3943_GPIO16,
 39	LP3943_MAX_GPIO,
 40};
 41
 42struct lp3943_gpio {
 43	struct gpio_chip chip;
 44	struct lp3943 *lp3943;
 45	u16 input_mask;		/* 1 = GPIO is input direction, 0 = output */
 46};
 47
 48static inline struct lp3943_gpio *to_lp3943_gpio(struct gpio_chip *_chip)
 49{
 50	return container_of(_chip, struct lp3943_gpio, chip);
 51}
 52
 53static int lp3943_gpio_request(struct gpio_chip *chip, unsigned offset)
 54{
 55	struct lp3943_gpio *lp3943_gpio = to_lp3943_gpio(chip);
 56	struct lp3943 *lp3943 = lp3943_gpio->lp3943;
 57
 58	/* Return an error if the pin is already assigned */
 59	if (test_and_set_bit(offset, &lp3943->pin_used))
 60		return -EBUSY;
 61
 62	return 0;
 63}
 64
 65static void lp3943_gpio_free(struct gpio_chip *chip, unsigned offset)
 66{
 67	struct lp3943_gpio *lp3943_gpio = to_lp3943_gpio(chip);
 68	struct lp3943 *lp3943 = lp3943_gpio->lp3943;
 69
 70	clear_bit(offset, &lp3943->pin_used);
 71}
 72
 73static int lp3943_gpio_set_mode(struct lp3943_gpio *lp3943_gpio, u8 offset,
 74				u8 val)
 75{
 76	struct lp3943 *lp3943 = lp3943_gpio->lp3943;
 77	const struct lp3943_reg_cfg *mux = lp3943->mux_cfg;
 78
 79	return lp3943_update_bits(lp3943, mux[offset].reg, mux[offset].mask,
 80				  val << mux[offset].shift);
 81}
 82
 83static int lp3943_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
 84{
 85	struct lp3943_gpio *lp3943_gpio = to_lp3943_gpio(chip);
 86
 87	lp3943_gpio->input_mask |= BIT(offset);
 88
 89	return lp3943_gpio_set_mode(lp3943_gpio, offset, LP3943_GPIO_IN);
 90}
 91
 92static int lp3943_get_gpio_in_status(struct lp3943_gpio *lp3943_gpio,
 93				     struct gpio_chip *chip, unsigned offset)
 94{
 95	u8 addr, read;
 96	int err;
 97
 98	switch (offset) {
 99	case LP3943_GPIO1 ... LP3943_GPIO8:
100		addr = LP3943_REG_GPIO_A;
101		break;
102	case LP3943_GPIO9 ... LP3943_GPIO16:
103		addr = LP3943_REG_GPIO_B;
104		offset = offset - 8;
105		break;
106	default:
107		return -EINVAL;
108	}
109
110	err = lp3943_read_byte(lp3943_gpio->lp3943, addr, &read);
111	if (err)
112		return err;
113
114	return !!(read & BIT(offset));
115}
116
117static int lp3943_get_gpio_out_status(struct lp3943_gpio *lp3943_gpio,
118				      struct gpio_chip *chip, unsigned offset)
119{
120	struct lp3943 *lp3943 = lp3943_gpio->lp3943;
121	const struct lp3943_reg_cfg *mux = lp3943->mux_cfg;
122	u8 read;
123	int err;
124
125	err = lp3943_read_byte(lp3943, mux[offset].reg, &read);
126	if (err)
127		return err;
128
129	read = (read & mux[offset].mask) >> mux[offset].shift;
130
131	if (read == LP3943_GPIO_OUT_HIGH)
132		return 1;
133	else if (read == LP3943_GPIO_OUT_LOW)
134		return 0;
135	else
136		return -EINVAL;
137}
138
139static int lp3943_gpio_get(struct gpio_chip *chip, unsigned offset)
140{
141	struct lp3943_gpio *lp3943_gpio = to_lp3943_gpio(chip);
142
143	/*
144	 * Limitation:
145	 *   LP3943 doesn't have the GPIO direction register. It provides
146	 *   only input and output status registers.
147	 *   So, direction info is required to handle the 'get' operation.
148	 *   This variable is updated whenever the direction is changed and
149	 *   it is used here.
150	 */
151
152	if (lp3943_gpio->input_mask & BIT(offset))
153		return lp3943_get_gpio_in_status(lp3943_gpio, chip, offset);
154	else
155		return lp3943_get_gpio_out_status(lp3943_gpio, chip, offset);
156}
157
158static void lp3943_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
159{
160	struct lp3943_gpio *lp3943_gpio = to_lp3943_gpio(chip);
161	u8 data;
162
163	if (value)
164		data = LP3943_GPIO_OUT_HIGH;
165	else
166		data = LP3943_GPIO_OUT_LOW;
167
168	lp3943_gpio_set_mode(lp3943_gpio, offset, data);
169}
170
171static int lp3943_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
172					int value)
173{
174	struct lp3943_gpio *lp3943_gpio = to_lp3943_gpio(chip);
175
176	lp3943_gpio_set(chip, offset, value);
177	lp3943_gpio->input_mask &= ~BIT(offset);
178
179	return 0;
180}
181
182static const struct gpio_chip lp3943_gpio_chip = {
183	.label			= "lp3943",
184	.owner			= THIS_MODULE,
185	.request		= lp3943_gpio_request,
186	.free			= lp3943_gpio_free,
187	.direction_input	= lp3943_gpio_direction_input,
188	.get			= lp3943_gpio_get,
189	.direction_output	= lp3943_gpio_direction_output,
190	.set			= lp3943_gpio_set,
191	.base			= -1,
192	.ngpio			= LP3943_MAX_GPIO,
193	.can_sleep		= 1,
194};
195
196static int lp3943_gpio_probe(struct platform_device *pdev)
197{
198	struct lp3943 *lp3943 = dev_get_drvdata(pdev->dev.parent);
199	struct lp3943_gpio *lp3943_gpio;
200
201	lp3943_gpio = devm_kzalloc(&pdev->dev, sizeof(*lp3943_gpio),
202				GFP_KERNEL);
203	if (!lp3943_gpio)
204		return -ENOMEM;
205
206	lp3943_gpio->lp3943 = lp3943;
207	lp3943_gpio->chip = lp3943_gpio_chip;
208	lp3943_gpio->chip.dev = &pdev->dev;
209
210	platform_set_drvdata(pdev, lp3943_gpio);
211
212	return gpiochip_add(&lp3943_gpio->chip);
213}
214
215static int lp3943_gpio_remove(struct platform_device *pdev)
216{
217	struct lp3943_gpio *lp3943_gpio = platform_get_drvdata(pdev);
218
219	return gpiochip_remove(&lp3943_gpio->chip);
220}
221
222static const struct of_device_id lp3943_gpio_of_match[] = {
223	{ .compatible = "ti,lp3943-gpio", },
224	{ }
225};
226MODULE_DEVICE_TABLE(of, lp3943_gpio_of_match);
227
228static struct platform_driver lp3943_gpio_driver = {
229	.probe = lp3943_gpio_probe,
230	.remove = lp3943_gpio_remove,
231	.driver = {
232		.name = "lp3943-gpio",
233		.owner = THIS_MODULE,
234		.of_match_table = lp3943_gpio_of_match,
235	},
236};
237module_platform_driver(lp3943_gpio_driver);
238
239MODULE_DESCRIPTION("LP3943 GPIO driver");
240MODULE_ALIAS("platform:lp3943-gpio");
241MODULE_AUTHOR("Milo Kim");
242MODULE_LICENSE("GPL");