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
32 static DEFINE_IDA(ida_index);
33
34 struct 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
47 static unsigned int
exar_offset_to_sel_addr(struct exar_gpio_chip * exar_gpio,unsigned int offset)48 exar_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
57 static unsigned int
exar_offset_to_lvl_addr(struct exar_gpio_chip * exar_gpio,unsigned int offset)58 exar_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
67 static unsigned int
exar_offset_to_bit(struct exar_gpio_chip * exar_gpio,unsigned int offset)68 exar_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
exar_get_direction(struct gpio_chip * chip,unsigned int offset)75 static 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
exar_get_value(struct gpio_chip * chip,unsigned int offset)87 static 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
exar_set_value(struct gpio_chip * chip,unsigned int offset,int value)96 static 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 = exar_offset_to_lvl_addr(exar_gpio, offset);
101 unsigned int bit = exar_offset_to_bit(exar_gpio, offset);
102
103 if (value)
104 regmap_set_bits(exar_gpio->regmap, addr, BIT(bit));
105 else
106 regmap_clear_bits(exar_gpio->regmap, addr, BIT(bit));
107 }
108
exar_direction_output(struct gpio_chip * chip,unsigned int offset,int value)109 static int exar_direction_output(struct gpio_chip *chip, unsigned int offset,
110 int value)
111 {
112 struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
113 unsigned int addr = exar_offset_to_sel_addr(exar_gpio, offset);
114 unsigned int bit = exar_offset_to_bit(exar_gpio, offset);
115
116 exar_set_value(chip, offset, value);
117 regmap_clear_bits(exar_gpio->regmap, addr, BIT(bit));
118
119 return 0;
120 }
121
exar_direction_input(struct gpio_chip * chip,unsigned int offset)122 static int exar_direction_input(struct gpio_chip *chip, unsigned int offset)
123 {
124 struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
125 unsigned int addr = exar_offset_to_sel_addr(exar_gpio, offset);
126 unsigned int bit = exar_offset_to_bit(exar_gpio, offset);
127
128 regmap_set_bits(exar_gpio->regmap, addr, BIT(bit));
129
130 return 0;
131 }
132
exar_devm_ida_free(void * data)133 static void exar_devm_ida_free(void *data)
134 {
135 struct exar_gpio_chip *exar_gpio = data;
136
137 ida_free(&ida_index, exar_gpio->index);
138 }
139
140 static const struct regmap_config exar_regmap_config = {
141 .name = "exar-gpio",
142 .reg_bits = 16,
143 .val_bits = 8,
144 .io_port = true,
145 };
146
gpio_exar_probe(struct platform_device * pdev)147 static int gpio_exar_probe(struct platform_device *pdev)
148 {
149 struct device *dev = &pdev->dev;
150 struct pci_dev *pcidev = to_pci_dev(dev->parent);
151 struct exar_gpio_chip *exar_gpio;
152 u32 first_pin, ngpios;
153 void __iomem *p;
154 int index, ret;
155
156 /*
157 * The UART driver must have mapped region 0 prior to registering this
158 * device - use it.
159 */
160 p = pcim_iomap_table(pcidev)[0];
161 if (!p)
162 return -ENOMEM;
163
164 ret = device_property_read_u32(dev, "exar,first-pin", &first_pin);
165 if (ret)
166 return ret;
167
168 ret = device_property_read_u32(dev, "ngpios", &ngpios);
169 if (ret)
170 return ret;
171
172 exar_gpio = devm_kzalloc(dev, sizeof(*exar_gpio), GFP_KERNEL);
173 if (!exar_gpio)
174 return -ENOMEM;
175
176 /*
177 * If cascaded, secondary xr17v354 or xr17v358 have the same amount
178 * of MPIOs as their primaries and the last 4 bits of the primary's
179 * PCI Device ID is the number of its UART channels.
180 */
181 if (pcidev->device & GENMASK(15, 12)) {
182 ngpios += ngpios;
183 exar_gpio->cascaded_offset = (pcidev->device & GENMASK(3, 0)) *
184 EXAR_UART_CHANNEL_SIZE;
185 }
186
187 /*
188 * We don't need to check the return values of mmio regmap operations (unless
189 * the regmap has a clock attached which is not the case here).
190 */
191 exar_gpio->regmap = devm_regmap_init_mmio(dev, p, &exar_regmap_config);
192 if (IS_ERR(exar_gpio->regmap))
193 return PTR_ERR(exar_gpio->regmap);
194
195 index = ida_alloc(&ida_index, GFP_KERNEL);
196 if (index < 0)
197 return index;
198
199 ret = devm_add_action_or_reset(dev, exar_devm_ida_free, exar_gpio);
200 if (ret)
201 return ret;
202
203 sprintf(exar_gpio->name, "exar_gpio%d", index);
204 exar_gpio->gpio_chip.label = exar_gpio->name;
205 exar_gpio->gpio_chip.parent = dev;
206 exar_gpio->gpio_chip.direction_output = exar_direction_output;
207 exar_gpio->gpio_chip.direction_input = exar_direction_input;
208 exar_gpio->gpio_chip.get_direction = exar_get_direction;
209 exar_gpio->gpio_chip.get = exar_get_value;
210 exar_gpio->gpio_chip.set = exar_set_value;
211 exar_gpio->gpio_chip.base = -1;
212 exar_gpio->gpio_chip.ngpio = ngpios;
213 exar_gpio->index = index;
214 exar_gpio->first_pin = first_pin;
215
216 ret = devm_gpiochip_add_data(dev, &exar_gpio->gpio_chip, exar_gpio);
217 if (ret)
218 return ret;
219
220 return 0;
221 }
222
223 static struct platform_driver gpio_exar_driver = {
224 .probe = gpio_exar_probe,
225 .driver = {
226 .name = DRIVER_NAME,
227 },
228 };
229
230 module_platform_driver(gpio_exar_driver);
231
232 MODULE_ALIAS("platform:" DRIVER_NAME);
233 MODULE_DESCRIPTION("Exar GPIO driver");
234 MODULE_AUTHOR("Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>");
235 MODULE_LICENSE("GPL");
236