Linux kernel mirror (for testing)
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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
8#include <linux/bitops.h>
9#include <linux/device.h>
10#include <linux/gpio/driver.h>
11#include <linux/idr.h>
12#include <linux/init.h>
13#include <linux/kernel.h>
14#include <linux/module.h>
15#include <linux/pci.h>
16#include <linux/platform_device.h>
17#include <linux/regmap.h>
18
19#define EXAR_OFFSET_MPIOLVL_LO 0x90
20#define EXAR_OFFSET_MPIOSEL_LO 0x93
21#define EXAR_OFFSET_MPIOLVL_HI 0x96
22#define EXAR_OFFSET_MPIOSEL_HI 0x99
23
24/*
25 * The Device Configuration and UART Configuration Registers
26 * for each UART channel take 1KB of memory address space.
27 */
28#define EXAR_UART_CHANNEL_SIZE 0x400
29
30#define DRIVER_NAME "gpio_exar"
31
32static DEFINE_IDA(ida_index);
33
34struct exar_gpio_chip {
35 struct gpio_chip gpio_chip;
36 struct regmap *regmap;
37 int index;
38 char name[20];
39 unsigned int first_pin;
40 /*
41 * The offset to the cascaded device's (if existing)
42 * Device Configuration Registers.
43 */
44 unsigned int cascaded_offset;
45};
46
47static unsigned int
48exar_offset_to_sel_addr(struct exar_gpio_chip *exar_gpio, unsigned int offset)
49{
50 unsigned int pin = exar_gpio->first_pin + (offset % 16);
51 unsigned int cascaded = offset / 16;
52 unsigned int addr = pin / 8 ? EXAR_OFFSET_MPIOSEL_HI : EXAR_OFFSET_MPIOSEL_LO;
53
54 return addr + (cascaded ? exar_gpio->cascaded_offset : 0);
55}
56
57static unsigned int
58exar_offset_to_lvl_addr(struct exar_gpio_chip *exar_gpio, unsigned int offset)
59{
60 unsigned int pin = exar_gpio->first_pin + (offset % 16);
61 unsigned int cascaded = offset / 16;
62 unsigned int addr = pin / 8 ? EXAR_OFFSET_MPIOLVL_HI : EXAR_OFFSET_MPIOLVL_LO;
63
64 return addr + (cascaded ? exar_gpio->cascaded_offset : 0);
65}
66
67static unsigned int
68exar_offset_to_bit(struct exar_gpio_chip *exar_gpio, unsigned int offset)
69{
70 unsigned int pin = exar_gpio->first_pin + (offset % 16);
71
72 return pin % 8;
73}
74
75static int exar_get_direction(struct gpio_chip *chip, unsigned int offset)
76{
77 struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
78 unsigned int addr = exar_offset_to_sel_addr(exar_gpio, offset);
79 unsigned int bit = exar_offset_to_bit(exar_gpio, offset);
80
81 if (regmap_test_bits(exar_gpio->regmap, addr, BIT(bit)))
82 return GPIO_LINE_DIRECTION_IN;
83
84 return GPIO_LINE_DIRECTION_OUT;
85}
86
87static int exar_get_value(struct gpio_chip *chip, unsigned int offset)
88{
89 struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
90 unsigned int addr = exar_offset_to_lvl_addr(exar_gpio, offset);
91 unsigned int bit = exar_offset_to_bit(exar_gpio, offset);
92
93 return !!(regmap_test_bits(exar_gpio->regmap, addr, BIT(bit)));
94}
95
96static int 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 = exar_offset_to_lvl_addr(exar_gpio, offset);
101 unsigned int bit = exar_offset_to_bit(exar_gpio, offset);
102 unsigned int bit_value = value ? BIT(bit) : 0;
103
104 /*
105 * regmap_write_bits() forces value to be written when an external
106 * pull up/down might otherwise indicate value was already set.
107 */
108 return regmap_write_bits(exar_gpio->regmap, addr, BIT(bit), bit_value);
109}
110
111static int exar_direction_output(struct gpio_chip *chip, unsigned int offset,
112 int value)
113{
114 struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
115 unsigned int addr = exar_offset_to_sel_addr(exar_gpio, offset);
116 unsigned int bit = exar_offset_to_bit(exar_gpio, offset);
117 int ret;
118
119 ret = exar_set_value(chip, offset, value);
120 if (ret)
121 return ret;
122
123 return regmap_clear_bits(exar_gpio->regmap, addr, BIT(bit));
124}
125
126static int exar_direction_input(struct gpio_chip *chip, unsigned int offset)
127{
128 struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
129 unsigned int addr = exar_offset_to_sel_addr(exar_gpio, offset);
130 unsigned int bit = exar_offset_to_bit(exar_gpio, offset);
131
132 regmap_set_bits(exar_gpio->regmap, addr, BIT(bit));
133
134 return 0;
135}
136
137static void exar_devm_ida_free(void *data)
138{
139 struct exar_gpio_chip *exar_gpio = data;
140
141 ida_free(&ida_index, exar_gpio->index);
142}
143
144static const struct regmap_config exar_regmap_config = {
145 .name = "exar-gpio",
146 .reg_bits = 16,
147 .val_bits = 8,
148 .io_port = true,
149};
150
151static int gpio_exar_probe(struct platform_device *pdev)
152{
153 struct device *dev = &pdev->dev;
154 struct pci_dev *pcidev = to_pci_dev(dev->parent);
155 struct exar_gpio_chip *exar_gpio;
156 u32 first_pin, ngpios;
157 void __iomem *p;
158 int index, ret;
159
160 /*
161 * The UART driver must have mapped region 0 prior to registering this
162 * device - use it.
163 */
164 p = pcim_iomap_table(pcidev)[0];
165 if (!p)
166 return -ENOMEM;
167
168 ret = device_property_read_u32(dev, "exar,first-pin", &first_pin);
169 if (ret)
170 return ret;
171
172 ret = device_property_read_u32(dev, "ngpios", &ngpios);
173 if (ret)
174 return ret;
175
176 exar_gpio = devm_kzalloc(dev, sizeof(*exar_gpio), GFP_KERNEL);
177 if (!exar_gpio)
178 return -ENOMEM;
179
180 /*
181 * If cascaded, secondary xr17v354 or xr17v358 have the same amount
182 * of MPIOs as their primaries and the last 4 bits of the primary's
183 * PCI Device ID is the number of its UART channels.
184 */
185 if (pcidev->device & GENMASK(15, 12)) {
186 ngpios += ngpios;
187 exar_gpio->cascaded_offset = (pcidev->device & GENMASK(3, 0)) *
188 EXAR_UART_CHANNEL_SIZE;
189 }
190
191 /*
192 * We don't need to check the return values of mmio regmap operations (unless
193 * the regmap has a clock attached which is not the case here).
194 */
195 exar_gpio->regmap = devm_regmap_init_mmio(dev, p, &exar_regmap_config);
196 if (IS_ERR(exar_gpio->regmap))
197 return PTR_ERR(exar_gpio->regmap);
198
199 index = ida_alloc(&ida_index, GFP_KERNEL);
200 if (index < 0)
201 return index;
202
203 ret = devm_add_action_or_reset(dev, exar_devm_ida_free, exar_gpio);
204 if (ret)
205 return ret;
206
207 sprintf(exar_gpio->name, "exar_gpio%d", index);
208 exar_gpio->gpio_chip.label = exar_gpio->name;
209 exar_gpio->gpio_chip.parent = dev;
210 exar_gpio->gpio_chip.direction_output = exar_direction_output;
211 exar_gpio->gpio_chip.direction_input = exar_direction_input;
212 exar_gpio->gpio_chip.get_direction = exar_get_direction;
213 exar_gpio->gpio_chip.get = exar_get_value;
214 exar_gpio->gpio_chip.set = exar_set_value;
215 exar_gpio->gpio_chip.base = -1;
216 exar_gpio->gpio_chip.ngpio = ngpios;
217 exar_gpio->index = index;
218 exar_gpio->first_pin = first_pin;
219
220 ret = devm_gpiochip_add_data(dev, &exar_gpio->gpio_chip, exar_gpio);
221 if (ret)
222 return ret;
223
224 return 0;
225}
226
227static struct platform_driver gpio_exar_driver = {
228 .probe = gpio_exar_probe,
229 .driver = {
230 .name = DRIVER_NAME,
231 },
232};
233
234module_platform_driver(gpio_exar_driver);
235
236MODULE_ALIAS("platform:" DRIVER_NAME);
237MODULE_DESCRIPTION("Exar GPIO driver");
238MODULE_AUTHOR("Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>");
239MODULE_LICENSE("GPL");