1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * GPIO driver for Exar XR17V35X chip
4 *
5 * Copyright (C) 2015 Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
6 */
7#include <linux/bitops.h>
8#include <linux/device.h>
9#include <linux/gpio/driver.h>
10#include <linux/init.h>
11#include <linux/kernel.h>
12#include <linux/module.h>
13#include <linux/pci.h>
14#include <linux/platform_device.h>
15
16#define EXAR_OFFSET_MPIOLVL_LO 0x90
17#define EXAR_OFFSET_MPIOSEL_LO 0x93
18#define EXAR_OFFSET_MPIOLVL_HI 0x96
19#define EXAR_OFFSET_MPIOSEL_HI 0x99
20
21#define DRIVER_NAME "gpio_exar"
22
23static DEFINE_IDA(ida_index);
24
25struct exar_gpio_chip {
26	struct gpio_chip gpio_chip;
27	struct mutex lock;
28	int index;
29	void __iomem *regs;
30	char name[20];
31	unsigned int first_pin;
32};
33
34static void exar_update(struct gpio_chip *chip, unsigned int reg, int val,
35			unsigned int offset)
36{
37	struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
38	int temp;
39
40	mutex_lock(&exar_gpio->lock);
41	temp = readb(exar_gpio->regs + reg);
42	temp &= ~BIT(offset);
43	if (val)
44		temp |= BIT(offset);
45	writeb(temp, exar_gpio->regs + reg);
46	mutex_unlock(&exar_gpio->lock);
47}
48
49static int exar_set_direction(struct gpio_chip *chip, int direction,
50			      unsigned int offset)
51{
52	struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
53	unsigned int addr = (offset + exar_gpio->first_pin) / 8 ?
54		EXAR_OFFSET_MPIOSEL_HI : EXAR_OFFSET_MPIOSEL_LO;
55	unsigned int bit  = (offset + exar_gpio->first_pin) % 8;
56
57	exar_update(chip, addr, direction, bit);
58	return 0;
59}
60
61static int exar_get(struct gpio_chip *chip, unsigned int reg)
62{
63	struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
64	int value;
65
66	mutex_lock(&exar_gpio->lock);
67	value = readb(exar_gpio->regs + reg);
68	mutex_unlock(&exar_gpio->lock);
69
70	return value;
71}
72
73static int exar_get_direction(struct gpio_chip *chip, unsigned int offset)
74{
75	struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
76	unsigned int addr = (offset + exar_gpio->first_pin) / 8 ?
77		EXAR_OFFSET_MPIOSEL_HI : EXAR_OFFSET_MPIOSEL_LO;
78	unsigned int bit  = (offset + exar_gpio->first_pin) % 8;
79
80	if (exar_get(chip, addr) & BIT(bit))
81		return GPIO_LINE_DIRECTION_IN;
82
83	return GPIO_LINE_DIRECTION_OUT;
84}
85
86static int exar_get_value(struct gpio_chip *chip, unsigned int offset)
87{
88	struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
89	unsigned int addr = (offset + exar_gpio->first_pin) / 8 ?
90		EXAR_OFFSET_MPIOLVL_HI : EXAR_OFFSET_MPIOLVL_LO;
91	unsigned int bit  = (offset + exar_gpio->first_pin) % 8;
92
93	return !!(exar_get(chip, addr) & BIT(bit));
94}
95
96static void exar_set_value(struct gpio_chip *chip, unsigned int offset,
97			   int value)
98{
99	struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
100	unsigned int addr = (offset + exar_gpio->first_pin) / 8 ?
101		EXAR_OFFSET_MPIOLVL_HI : EXAR_OFFSET_MPIOLVL_LO;
102	unsigned int bit  = (offset + exar_gpio->first_pin) % 8;
103
104	exar_update(chip, addr, value, bit);
105}
106
107static int exar_direction_output(struct gpio_chip *chip, unsigned int offset,
108				 int value)
109{
110	exar_set_value(chip, offset, value);
111	return exar_set_direction(chip, 0, offset);
112}
113
114static int exar_direction_input(struct gpio_chip *chip, unsigned int offset)
115{
116	return exar_set_direction(chip, 1, offset);
117}
118
119static int gpio_exar_probe(struct platform_device *pdev)
120{
121	struct pci_dev *pcidev = to_pci_dev(pdev->dev.parent);
122	struct exar_gpio_chip *exar_gpio;
123	u32 first_pin, ngpios;
124	void __iomem *p;
125	int index, ret;
126
127	/*
128	 * The UART driver must have mapped region 0 prior to registering this
129	 * device - use it.
130	 */
131	p = pcim_iomap_table(pcidev)[0];
132	if (!p)
133		return -ENOMEM;
134
135	ret = device_property_read_u32(&pdev->dev, "exar,first-pin",
136				       &first_pin);
137	if (ret)
138		return ret;
139
140	ret = device_property_read_u32(&pdev->dev, "ngpios", &ngpios);
141	if (ret)
142		return ret;
143
144	exar_gpio = devm_kzalloc(&pdev->dev, sizeof(*exar_gpio), GFP_KERNEL);
145	if (!exar_gpio)
146		return -ENOMEM;
147
148	mutex_init(&exar_gpio->lock);
149
150	index = ida_simple_get(&ida_index, 0, 0, GFP_KERNEL);
151	if (index < 0) {
152		ret = index;
153		goto err_mutex_destroy;
154	}
155
156	sprintf(exar_gpio->name, "exar_gpio%d", index);
157	exar_gpio->gpio_chip.label = exar_gpio->name;
158	exar_gpio->gpio_chip.parent = &pdev->dev;
159	exar_gpio->gpio_chip.direction_output = exar_direction_output;
160	exar_gpio->gpio_chip.direction_input = exar_direction_input;
161	exar_gpio->gpio_chip.get_direction = exar_get_direction;
162	exar_gpio->gpio_chip.get = exar_get_value;
163	exar_gpio->gpio_chip.set = exar_set_value;
164	exar_gpio->gpio_chip.base = -1;
165	exar_gpio->gpio_chip.ngpio = ngpios;
166	exar_gpio->regs = p;
167	exar_gpio->index = index;
168	exar_gpio->first_pin = first_pin;
169
170	ret = devm_gpiochip_add_data(&pdev->dev,
171				     &exar_gpio->gpio_chip, exar_gpio);
172	if (ret)
173		goto err_destroy;
174
175	platform_set_drvdata(pdev, exar_gpio);
176
177	return 0;
178
179err_destroy:
180	ida_simple_remove(&ida_index, index);
181err_mutex_destroy:
182	mutex_destroy(&exar_gpio->lock);
183	return ret;
184}
185
186static int gpio_exar_remove(struct platform_device *pdev)
187{
188	struct exar_gpio_chip *exar_gpio = platform_get_drvdata(pdev);
189
190	ida_simple_remove(&ida_index, exar_gpio->index);
191	mutex_destroy(&exar_gpio->lock);
192
193	return 0;
194}
195
196static struct platform_driver gpio_exar_driver = {
197	.probe	= gpio_exar_probe,
198	.remove	= gpio_exar_remove,
199	.driver	= {
200		.name = DRIVER_NAME,
201	},
202};
203
204module_platform_driver(gpio_exar_driver);
205
206MODULE_ALIAS("platform:" DRIVER_NAME);
207MODULE_DESCRIPTION("Exar GPIO driver");
208MODULE_AUTHOR("Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>");
209MODULE_LICENSE("GPL");
210