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/driver.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");
206