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	return !!(exar_get(chip, addr) & BIT(bit));
 81}
 82
 83static 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
 93static 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
104static 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
111static int exar_direction_input(struct gpio_chip *chip, unsigned int offset)
112{
113	return exar_set_direction(chip, 1, offset);
114}
115
116static 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		goto err_destroy;
150
151	sprintf(exar_gpio->name, "exar_gpio%d", index);
152	exar_gpio->gpio_chip.label = exar_gpio->name;
153	exar_gpio->gpio_chip.parent = &pdev->dev;
154	exar_gpio->gpio_chip.direction_output = exar_direction_output;
155	exar_gpio->gpio_chip.direction_input = exar_direction_input;
156	exar_gpio->gpio_chip.get_direction = exar_get_direction;
157	exar_gpio->gpio_chip.get = exar_get_value;
158	exar_gpio->gpio_chip.set = exar_set_value;
159	exar_gpio->gpio_chip.base = -1;
160	exar_gpio->gpio_chip.ngpio = ngpios;
161	exar_gpio->regs = p;
162	exar_gpio->index = index;
163	exar_gpio->first_pin = first_pin;
164
165	ret = devm_gpiochip_add_data(&pdev->dev,
166				     &exar_gpio->gpio_chip, exar_gpio);
167	if (ret)
168		goto err_destroy;
169
170	platform_set_drvdata(pdev, exar_gpio);
171
172	return 0;
173
174err_destroy:
175	ida_simple_remove(&ida_index, index);
176	mutex_destroy(&exar_gpio->lock);
177	return ret;
178}
179
180static int gpio_exar_remove(struct platform_device *pdev)
181{
182	struct exar_gpio_chip *exar_gpio = platform_get_drvdata(pdev);
183
184	ida_simple_remove(&ida_index, exar_gpio->index);
185	mutex_destroy(&exar_gpio->lock);
186
187	return 0;
188}
189
190static struct platform_driver gpio_exar_driver = {
191	.probe	= gpio_exar_probe,
192	.remove	= gpio_exar_remove,
193	.driver	= {
194		.name = DRIVER_NAME,
195	},
196};
197
198module_platform_driver(gpio_exar_driver);
199
200MODULE_ALIAS("platform:" DRIVER_NAME);
201MODULE_DESCRIPTION("Exar GPIO driver");
202MODULE_AUTHOR("Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>");
203MODULE_LICENSE("GPL");