tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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 goto err_destroy;
153
154 sprintf(exar_gpio->name, "exar_gpio%d", index);
155 exar_gpio->gpio_chip.label = exar_gpio->name;
156 exar_gpio->gpio_chip.parent = &pdev->dev;
157 exar_gpio->gpio_chip.direction_output = exar_direction_output;
158 exar_gpio->gpio_chip.direction_input = exar_direction_input;
159 exar_gpio->gpio_chip.get_direction = exar_get_direction;
160 exar_gpio->gpio_chip.get = exar_get_value;
161 exar_gpio->gpio_chip.set = exar_set_value;
162 exar_gpio->gpio_chip.base = -1;
163 exar_gpio->gpio_chip.ngpio = ngpios;
164 exar_gpio->regs = p;
165 exar_gpio->index = index;
166 exar_gpio->first_pin = first_pin;
167
168 ret = devm_gpiochip_add_data(&pdev->dev,
169 &exar_gpio->gpio_chip, exar_gpio);
170 if (ret)
171 goto err_destroy;
172
173 platform_set_drvdata(pdev, exar_gpio);
174
175 return 0;
176
177err_destroy:
178 ida_simple_remove(&ida_index, index);
179 mutex_destroy(&exar_gpio->lock);
180 return ret;
181}
182
183static int gpio_exar_remove(struct platform_device *pdev)
184{
185 struct exar_gpio_chip *exar_gpio = platform_get_drvdata(pdev);
186
187 ida_simple_remove(&ida_index, exar_gpio->index);
188 mutex_destroy(&exar_gpio->lock);
189
190 return 0;
191}
192
193static struct platform_driver gpio_exar_driver = {
194 .probe = gpio_exar_probe,
195 .remove = gpio_exar_remove,
196 .driver = {
197 .name = DRIVER_NAME,
198 },
199};
200
201module_platform_driver(gpio_exar_driver);
202
203MODULE_ALIAS("platform:" DRIVER_NAME);
204MODULE_DESCRIPTION("Exar GPIO driver");
205MODULE_AUTHOR("Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>");
206MODULE_LICENSE("GPL");