1/*
  2 * Kontron PLD GPIO driver
  3 *
  4 * Copyright (c) 2010-2013 Kontron Europe GmbH
  5 * Author: Michael Brunner <michael.brunner@kontron.com>
  6 *
  7 * This program is free software; you can redistribute it and/or modify
  8 * it under the terms of the GNU General Public License 2 as published
  9 * by the Free Software Foundation.
 10 *
 11 * This program is distributed in the hope that it will be useful,
 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14 * GNU General Public License for more details.
 15 */
 16
 17#include <linux/init.h>
 18#include <linux/kernel.h>
 19#include <linux/module.h>
 20#include <linux/bitops.h>
 21#include <linux/errno.h>
 22#include <linux/platform_device.h>
 23#include <linux/gpio.h>
 24#include <linux/mfd/kempld.h>
 25
 26#define KEMPLD_GPIO_MAX_NUM		16
 27#define KEMPLD_GPIO_MASK(x)		(BIT((x) % 8))
 28#define KEMPLD_GPIO_DIR_NUM(x)		(0x40 + (x) / 8)
 29#define KEMPLD_GPIO_LVL_NUM(x)		(0x42 + (x) / 8)
 30#define KEMPLD_GPIO_EVT_LVL_EDGE	0x46
 31#define KEMPLD_GPIO_IEN			0x4A
 32
 33struct kempld_gpio_data {
 34	struct gpio_chip		chip;
 35	struct kempld_device_data	*pld;
 36};
 37
 38/*
 39 * Set or clear GPIO bit
 40 * kempld_get_mutex must be called prior to calling this function.
 41 */
 42static void kempld_gpio_bitop(struct kempld_device_data *pld,
 43			      u8 reg, u8 bit, u8 val)
 44{
 45	u8 status;
 46
 47	status = kempld_read8(pld, reg);
 48	if (val)
 49		status |= KEMPLD_GPIO_MASK(bit);
 50	else
 51		status &= ~KEMPLD_GPIO_MASK(bit);
 52	kempld_write8(pld, reg, status);
 53}
 54
 55static int kempld_gpio_get_bit(struct kempld_device_data *pld, u8 reg, u8 bit)
 56{
 57	u8 status;
 58
 59	kempld_get_mutex(pld);
 60	status = kempld_read8(pld, reg);
 61	kempld_release_mutex(pld);
 62
 63	return !!(status & KEMPLD_GPIO_MASK(bit));
 64}
 65
 66static int kempld_gpio_get(struct gpio_chip *chip, unsigned offset)
 67{
 68	struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
 69	struct kempld_device_data *pld = gpio->pld;
 70
 71	return !!kempld_gpio_get_bit(pld, KEMPLD_GPIO_LVL_NUM(offset), offset);
 72}
 73
 74static void kempld_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
 75{
 76	struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
 77	struct kempld_device_data *pld = gpio->pld;
 78
 79	kempld_get_mutex(pld);
 80	kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value);
 81	kempld_release_mutex(pld);
 82}
 83
 84static int kempld_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
 85{
 86	struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
 87	struct kempld_device_data *pld = gpio->pld;
 88
 89	kempld_get_mutex(pld);
 90	kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 0);
 91	kempld_release_mutex(pld);
 92
 93	return 0;
 94}
 95
 96static int kempld_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
 97					int value)
 98{
 99	struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
100	struct kempld_device_data *pld = gpio->pld;
101
102	kempld_get_mutex(pld);
103	kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value);
104	kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 1);
105	kempld_release_mutex(pld);
106
107	return 0;
108}
109
110static int kempld_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
111{
112	struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
113	struct kempld_device_data *pld = gpio->pld;
114
115	return !kempld_gpio_get_bit(pld, KEMPLD_GPIO_DIR_NUM(offset), offset);
116}
117
118static int kempld_gpio_pincount(struct kempld_device_data *pld)
119{
120	u16 evt, evt_back;
121
122	kempld_get_mutex(pld);
123
124	/* Backup event register as it might be already initialized */
125	evt_back = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE);
126	/* Clear event register */
127	kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, 0x0000);
128	/* Read back event register */
129	evt = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE);
130	/* Restore event register */
131	kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, evt_back);
132
133	kempld_release_mutex(pld);
134
135	return evt ? __ffs(evt) : 16;
136}
137
138static int kempld_gpio_probe(struct platform_device *pdev)
139{
140	struct device *dev = &pdev->dev;
141	struct kempld_device_data *pld = dev_get_drvdata(dev->parent);
142	struct kempld_platform_data *pdata = dev_get_platdata(pld->dev);
143	struct kempld_gpio_data *gpio;
144	struct gpio_chip *chip;
145	int ret;
146
147	if (pld->info.spec_major < 2) {
148		dev_err(dev,
149			"Driver only supports GPIO devices compatible to PLD spec. rev. 2.0 or higher\n");
150		return -ENODEV;
151	}
152
153	gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL);
154	if (!gpio)
155		return -ENOMEM;
156
157	gpio->pld = pld;
158
159	platform_set_drvdata(pdev, gpio);
160
161	chip = &gpio->chip;
162	chip->label = "gpio-kempld";
163	chip->owner = THIS_MODULE;
164	chip->parent = dev;
165	chip->can_sleep = true;
166	if (pdata && pdata->gpio_base)
167		chip->base = pdata->gpio_base;
168	else
169		chip->base = -1;
170	chip->direction_input = kempld_gpio_direction_input;
171	chip->direction_output = kempld_gpio_direction_output;
172	chip->get_direction = kempld_gpio_get_direction;
173	chip->get = kempld_gpio_get;
174	chip->set = kempld_gpio_set;
175	chip->ngpio = kempld_gpio_pincount(pld);
176	if (chip->ngpio == 0) {
177		dev_err(dev, "No GPIO pins detected\n");
178		return -ENODEV;
179	}
180
181	ret = devm_gpiochip_add_data(dev, chip, gpio);
182	if (ret) {
183		dev_err(dev, "Could not register GPIO chip\n");
184		return ret;
185	}
186
187	dev_info(dev, "GPIO functionality initialized with %d pins\n",
188		 chip->ngpio);
189
190	return 0;
191}
192
193static struct platform_driver kempld_gpio_driver = {
194	.driver = {
195		.name = "kempld-gpio",
196	},
197	.probe		= kempld_gpio_probe,
198};
199
200module_platform_driver(kempld_gpio_driver);
201
202MODULE_DESCRIPTION("KEM PLD GPIO Driver");
203MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
204MODULE_LICENSE("GPL");
205MODULE_ALIAS("platform:kempld-gpio");