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");