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
69		= container_of(chip, struct kempld_gpio_data, chip);
70	struct kempld_device_data *pld = gpio->pld;
71
72	return kempld_gpio_get_bit(pld, KEMPLD_GPIO_LVL_NUM(offset), offset);
73}
74
75static void kempld_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
76{
77	struct kempld_gpio_data *gpio
78		= container_of(chip, struct kempld_gpio_data, chip);
79	struct kempld_device_data *pld = gpio->pld;
80
81	kempld_get_mutex(pld);
82	kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value);
83	kempld_release_mutex(pld);
84}
85
86static int kempld_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
87{
88	struct kempld_gpio_data *gpio
89		= container_of(chip, struct kempld_gpio_data, chip);
90	struct kempld_device_data *pld = gpio->pld;
91
92	kempld_get_mutex(pld);
93	kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 0);
94	kempld_release_mutex(pld);
95
96	return 0;
97}
98
99static int kempld_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
100					int value)
101{
102	struct kempld_gpio_data *gpio
103		= container_of(chip, struct kempld_gpio_data, chip);
104	struct kempld_device_data *pld = gpio->pld;
105
106	kempld_get_mutex(pld);
107	kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value);
108	kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 1);
109	kempld_release_mutex(pld);
110
111	return 0;
112}
113
114static int kempld_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
115{
116	struct kempld_gpio_data *gpio
117		= container_of(chip, struct kempld_gpio_data, chip);
118	struct kempld_device_data *pld = gpio->pld;
119
120	return !kempld_gpio_get_bit(pld, KEMPLD_GPIO_DIR_NUM(offset), offset);
121}
122
123static int kempld_gpio_pincount(struct kempld_device_data *pld)
124{
125	u16 evt, evt_back;
126
127	kempld_get_mutex(pld);
128
129	/* Backup event register as it might be already initialized */
130	evt_back = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE);
131	/* Clear event register */
132	kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, 0x0000);
133	/* Read back event register */
134	evt = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE);
135	/* Restore event register */
136	kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, evt_back);
137
138	kempld_release_mutex(pld);
139
140	return evt ? __ffs(evt) : 16;
141}
142
143static int kempld_gpio_probe(struct platform_device *pdev)
144{
145	struct device *dev = &pdev->dev;
146	struct kempld_device_data *pld = dev_get_drvdata(dev->parent);
147	struct kempld_platform_data *pdata = dev_get_platdata(pld->dev);
148	struct kempld_gpio_data *gpio;
149	struct gpio_chip *chip;
150	int ret;
151
152	if (pld->info.spec_major < 2) {
153		dev_err(dev,
154			"Driver only supports GPIO devices compatible to PLD spec. rev. 2.0 or higher\n");
155		return -ENODEV;
156	}
157
158	gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL);
159	if (!gpio)
160		return -ENOMEM;
161
162	gpio->pld = pld;
163
164	platform_set_drvdata(pdev, gpio);
165
166	chip = &gpio->chip;
167	chip->label = "gpio-kempld";
168	chip->owner = THIS_MODULE;
169	chip->dev = dev;
170	chip->can_sleep = true;
171	if (pdata && pdata->gpio_base)
172		chip->base = pdata->gpio_base;
173	else
174		chip->base = -1;
175	chip->direction_input = kempld_gpio_direction_input;
176	chip->direction_output = kempld_gpio_direction_output;
177	chip->get_direction = kempld_gpio_get_direction;
178	chip->get = kempld_gpio_get;
179	chip->set = kempld_gpio_set;
180	chip->ngpio = kempld_gpio_pincount(pld);
181	if (chip->ngpio == 0) {
182		dev_err(dev, "No GPIO pins detected\n");
183		return -ENODEV;
184	}
185
186	ret = gpiochip_add(chip);
187	if (ret) {
188		dev_err(dev, "Could not register GPIO chip\n");
189		return ret;
190	}
191
192	dev_info(dev, "GPIO functionality initialized with %d pins\n",
193		 chip->ngpio);
194
195	return 0;
196}
197
198static int kempld_gpio_remove(struct platform_device *pdev)
199{
200	struct kempld_gpio_data *gpio = platform_get_drvdata(pdev);
201
202	gpiochip_remove(&gpio->chip);
203	return 0;
204}
205
206static struct platform_driver kempld_gpio_driver = {
207	.driver = {
208		.name = "kempld-gpio",
209	},
210	.probe		= kempld_gpio_probe,
211	.remove		= kempld_gpio_remove,
212};
213
214module_platform_driver(kempld_gpio_driver);
215
216MODULE_DESCRIPTION("KEM PLD GPIO Driver");
217MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
218MODULE_LICENSE("GPL");
219MODULE_ALIAS("platform:kempld-gpio");
220