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
23 static DEFINE_IDA(ida_index);
24
25 struct 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
exar_update(struct gpio_chip * chip,unsigned int reg,int val,unsigned int offset)34 static 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
exar_set_direction(struct gpio_chip * chip,int direction,unsigned int offset)49 static 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
exar_get(struct gpio_chip * chip,unsigned int reg)61 static 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
exar_get_direction(struct gpio_chip * chip,unsigned int offset)73 static 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 return !!(exar_get(chip, addr) & BIT(bit));
81 }
82
exar_get_value(struct gpio_chip * chip,unsigned int offset)83 static int exar_get_value(struct gpio_chip *chip, unsigned int offset)
84 {
85 struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
86 unsigned int addr = (offset + exar_gpio->first_pin) / 8 ?
87 EXAR_OFFSET_MPIOLVL_HI : EXAR_OFFSET_MPIOLVL_LO;
88 unsigned int bit = (offset + exar_gpio->first_pin) % 8;
89
90 return !!(exar_get(chip, addr) & BIT(bit));
91 }
92
exar_set_value(struct gpio_chip * chip,unsigned int offset,int value)93 static void exar_set_value(struct gpio_chip *chip, unsigned int offset,
94 int value)
95 {
96 struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
97 unsigned int addr = (offset + exar_gpio->first_pin) / 8 ?
98 EXAR_OFFSET_MPIOLVL_HI : EXAR_OFFSET_MPIOLVL_LO;
99 unsigned int bit = (offset + exar_gpio->first_pin) % 8;
100
101 exar_update(chip, addr, value, bit);
102 }
103
exar_direction_output(struct gpio_chip * chip,unsigned int offset,int value)104 static int exar_direction_output(struct gpio_chip *chip, unsigned int offset,
105 int value)
106 {
107 exar_set_value(chip, offset, value);
108 return exar_set_direction(chip, 0, offset);
109 }
110
exar_direction_input(struct gpio_chip * chip,unsigned int offset)111 static int exar_direction_input(struct gpio_chip *chip, unsigned int offset)
112 {
113 return exar_set_direction(chip, 1, offset);
114 }
115
gpio_exar_probe(struct platform_device * pdev)116 static int gpio_exar_probe(struct platform_device *pdev)
117 {
118 struct pci_dev *pcidev = to_pci_dev(pdev->dev.parent);
119 struct exar_gpio_chip *exar_gpio;
120 u32 first_pin, ngpios;
121 void __iomem *p;
122 int index, ret;
123
124 /*
125 * The UART driver must have mapped region 0 prior to registering this
126 * device - use it.
127 */
128 p = pcim_iomap_table(pcidev)[0];
129 if (!p)
130 return -ENOMEM;
131
132 ret = device_property_read_u32(&pdev->dev, "exar,first-pin",
133 &first_pin);
134 if (ret)
135 return ret;
136
137 ret = device_property_read_u32(&pdev->dev, "ngpios", &ngpios);
138 if (ret)
139 return ret;
140
141 exar_gpio = devm_kzalloc(&pdev->dev, sizeof(*exar_gpio), GFP_KERNEL);
142 if (!exar_gpio)
143 return -ENOMEM;
144
145 mutex_init(&exar_gpio->lock);
146
147 index = ida_simple_get(&ida_index, 0, 0, GFP_KERNEL);
148 if (index < 0) {
149 ret = index;
150 goto err_mutex_destroy;
151 }
152
153 sprintf(exar_gpio->name, "exar_gpio%d", index);
154 exar_gpio->gpio_chip.label = exar_gpio->name;
155 exar_gpio->gpio_chip.parent = &pdev->dev;
156 exar_gpio->gpio_chip.direction_output = exar_direction_output;
157 exar_gpio->gpio_chip.direction_input = exar_direction_input;
158 exar_gpio->gpio_chip.get_direction = exar_get_direction;
159 exar_gpio->gpio_chip.get = exar_get_value;
160 exar_gpio->gpio_chip.set = exar_set_value;
161 exar_gpio->gpio_chip.base = -1;
162 exar_gpio->gpio_chip.ngpio = ngpios;
163 exar_gpio->regs = p;
164 exar_gpio->index = index;
165 exar_gpio->first_pin = first_pin;
166
167 ret = devm_gpiochip_add_data(&pdev->dev,
168 &exar_gpio->gpio_chip, exar_gpio);
169 if (ret)
170 goto err_destroy;
171
172 platform_set_drvdata(pdev, exar_gpio);
173
174 return 0;
175
176 err_destroy:
177 ida_simple_remove(&ida_index, index);
178 err_mutex_destroy:
179 mutex_destroy(&exar_gpio->lock);
180 return ret;
181 }
182
gpio_exar_remove(struct platform_device * pdev)183 static 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
193 static 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
201 module_platform_driver(gpio_exar_driver);
202
203 MODULE_ALIAS("platform:" DRIVER_NAME);
204 MODULE_DESCRIPTION("Exar GPIO driver");
205 MODULE_AUTHOR("Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>");
206 MODULE_LICENSE("GPL");
207