1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Kontron PLD GPIO driver
4 *
5 * Copyright (c) 2010-2013 Kontron Europe GmbH
6 * Author: Michael Brunner <michael.brunner@kontron.com>
7 */
8
9#include <linux/init.h>
10#include <linux/kernel.h>
11#include <linux/module.h>
12#include <linux/bitops.h>
13#include <linux/errno.h>
14#include <linux/platform_device.h>
15#include <linux/gpio/driver.h>
16#include <linux/mfd/kempld.h>
17
18#define KEMPLD_GPIO_MAX_NUM		16
19#define KEMPLD_GPIO_MASK(x)		(BIT((x) % 8))
20#define KEMPLD_GPIO_DIR_NUM(x)		(0x40 + (x) / 8)
21#define KEMPLD_GPIO_LVL_NUM(x)		(0x42 + (x) / 8)
22#define KEMPLD_GPIO_EVT_LVL_EDGE	0x46
23#define KEMPLD_GPIO_IEN			0x4A
24
25struct kempld_gpio_data {
26	struct gpio_chip		chip;
27	struct kempld_device_data	*pld;
28};
29
30/*
31 * Set or clear GPIO bit
32 * kempld_get_mutex must be called prior to calling this function.
33 */
34static void kempld_gpio_bitop(struct kempld_device_data *pld,
35			      u8 reg, u8 bit, u8 val)
36{
37	u8 status;
38
39	status = kempld_read8(pld, reg);
40	if (val)
41		status |= KEMPLD_GPIO_MASK(bit);
42	else
43		status &= ~KEMPLD_GPIO_MASK(bit);
44	kempld_write8(pld, reg, status);
45}
46
47static int kempld_gpio_get_bit(struct kempld_device_data *pld, u8 reg, u8 bit)
48{
49	u8 status;
50
51	kempld_get_mutex(pld);
52	status = kempld_read8(pld, reg);
53	kempld_release_mutex(pld);
54
55	return !!(status & KEMPLD_GPIO_MASK(bit));
56}
57
58static int kempld_gpio_get(struct gpio_chip *chip, unsigned offset)
59{
60	struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
61	struct kempld_device_data *pld = gpio->pld;
62
63	return !!kempld_gpio_get_bit(pld, KEMPLD_GPIO_LVL_NUM(offset), offset);
64}
65
66static void kempld_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
67{
68	struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
69	struct kempld_device_data *pld = gpio->pld;
70
71	kempld_get_mutex(pld);
72	kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value);
73	kempld_release_mutex(pld);
74}
75
76static int kempld_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
77{
78	struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
79	struct kempld_device_data *pld = gpio->pld;
80
81	kempld_get_mutex(pld);
82	kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 0);
83	kempld_release_mutex(pld);
84
85	return 0;
86}
87
88static int kempld_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
89					int value)
90{
91	struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
92	struct kempld_device_data *pld = gpio->pld;
93
94	kempld_get_mutex(pld);
95	kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value);
96	kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 1);
97	kempld_release_mutex(pld);
98
99	return 0;
100}
101
102static int kempld_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
103{
104	struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
105	struct kempld_device_data *pld = gpio->pld;
106
107	if (kempld_gpio_get_bit(pld, KEMPLD_GPIO_DIR_NUM(offset), offset))
108		return GPIO_LINE_DIRECTION_OUT;
109
110	return GPIO_LINE_DIRECTION_IN;
111}
112
113static int kempld_gpio_pincount(struct kempld_device_data *pld)
114{
115	u16 evt, evt_back;
116
117	kempld_get_mutex(pld);
118
119	/* Backup event register as it might be already initialized */
120	evt_back = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE);
121	/* Clear event register */
122	kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, 0x0000);
123	/* Read back event register */
124	evt = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE);
125	/* Restore event register */
126	kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, evt_back);
127
128	kempld_release_mutex(pld);
129
130	return evt ? __ffs(evt) : 16;
131}
132
133static int kempld_gpio_probe(struct platform_device *pdev)
134{
135	struct device *dev = &pdev->dev;
136	struct kempld_device_data *pld = dev_get_drvdata(dev->parent);
137	struct kempld_platform_data *pdata = dev_get_platdata(pld->dev);
138	struct kempld_gpio_data *gpio;
139	struct gpio_chip *chip;
140	int ret;
141
142	if (pld->info.spec_major < 2) {
143		dev_err(dev,
144			"Driver only supports GPIO devices compatible to PLD spec. rev. 2.0 or higher\n");
145		return -ENODEV;
146	}
147
148	gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL);
149	if (!gpio)
150		return -ENOMEM;
151
152	gpio->pld = pld;
153
154	platform_set_drvdata(pdev, gpio);
155
156	chip = &gpio->chip;
157	chip->label = "gpio-kempld";
158	chip->owner = THIS_MODULE;
159	chip->parent = dev;
160	chip->can_sleep = true;
161	if (pdata && pdata->gpio_base)
162		chip->base = pdata->gpio_base;
163	else
164		chip->base = -1;
165	chip->direction_input = kempld_gpio_direction_input;
166	chip->direction_output = kempld_gpio_direction_output;
167	chip->get_direction = kempld_gpio_get_direction;
168	chip->get = kempld_gpio_get;
169	chip->set = kempld_gpio_set;
170	chip->ngpio = kempld_gpio_pincount(pld);
171	if (chip->ngpio == 0) {
172		dev_err(dev, "No GPIO pins detected\n");
173		return -ENODEV;
174	}
175
176	ret = devm_gpiochip_add_data(dev, chip, gpio);
177	if (ret) {
178		dev_err(dev, "Could not register GPIO chip\n");
179		return ret;
180	}
181
182	dev_info(dev, "GPIO functionality initialized with %d pins\n",
183		 chip->ngpio);
184
185	return 0;
186}
187
188static struct platform_driver kempld_gpio_driver = {
189	.driver = {
190		.name = "kempld-gpio",
191	},
192	.probe		= kempld_gpio_probe,
193};
194
195module_platform_driver(kempld_gpio_driver);
196
197MODULE_DESCRIPTION("KEM PLD GPIO Driver");
198MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
199MODULE_LICENSE("GPL");
200MODULE_ALIAS("platform:kempld-gpio");
201