1/*
  2 * GPIO driver for Exar XR17V35X chip
  3 *
  4 * Copyright (C) 2015 Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License version 2 as
  8 * published by the Free Software Foundation.
  9 */
 10#include <linux/bitops.h>
 11#include <linux/device.h>
 12#include <linux/gpio/driver.h>
 13#include <linux/init.h>
 14#include <linux/kernel.h>
 15#include <linux/module.h>
 16#include <linux/pci.h>
 17#include <linux/platform_device.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#define DRIVER_NAME "gpio_exar"
 25
 26static DEFINE_IDA(ida_index);
 27
 28struct exar_gpio_chip {
 29	struct gpio_chip gpio_chip;
 30	struct mutex lock;
 31	int index;
 32	void __iomem *regs;
 33	char name[20];
 34	unsigned int first_pin;
 35};
 36
 37static void exar_update(struct gpio_chip *chip, unsigned int reg, int val,
 38			unsigned int offset)
 39{
 40	struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
 41	int temp;
 42
 43	mutex_lock(&exar_gpio->lock);
 44	temp = readb(exar_gpio->regs + reg);
 45	temp &= ~BIT(offset);
 46	if (val)
 47		temp |= BIT(offset);
 48	writeb(temp, exar_gpio->regs + reg);
 49	mutex_unlock(&exar_gpio->lock);
 50}
 51
 52static int exar_set_direction(struct gpio_chip *chip, int direction,
 53			      unsigned int offset)
 54{
 55	struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
 56	unsigned int addr = (offset + exar_gpio->first_pin) / 8 ?
 57		EXAR_OFFSET_MPIOSEL_HI : EXAR_OFFSET_MPIOSEL_LO;
 58	unsigned int bit  = (offset + exar_gpio->first_pin) % 8;
 59
 60	exar_update(chip, addr, direction, bit);
 61	return 0;
 62}
 63
 64static int exar_get(struct gpio_chip *chip, unsigned int reg)
 65{
 66	struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
 67	int value;
 68
 69	mutex_lock(&exar_gpio->lock);
 70	value = readb(exar_gpio->regs + reg);
 71	mutex_unlock(&exar_gpio->lock);
 72
 73	return value;
 74}
 75
 76static int exar_get_direction(struct gpio_chip *chip, unsigned int offset)
 77{
 78	struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
 79	unsigned int addr = (offset + exar_gpio->first_pin) / 8 ?
 80		EXAR_OFFSET_MPIOSEL_HI : EXAR_OFFSET_MPIOSEL_LO;
 81	unsigned int bit  = (offset + exar_gpio->first_pin) % 8;
 82
 83	return !!(exar_get(chip, addr) & BIT(bit));
 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
152	sprintf(exar_gpio->name, "exar_gpio%d", index);
153	exar_gpio->gpio_chip.label = exar_gpio->name;
154	exar_gpio->gpio_chip.parent = &pdev->dev;
155	exar_gpio->gpio_chip.direction_output = exar_direction_output;
156	exar_gpio->gpio_chip.direction_input = exar_direction_input;
157	exar_gpio->gpio_chip.get_direction = exar_get_direction;
158	exar_gpio->gpio_chip.get = exar_get_value;
159	exar_gpio->gpio_chip.set = exar_set_value;
160	exar_gpio->gpio_chip.base = -1;
161	exar_gpio->gpio_chip.ngpio = ngpios;
162	exar_gpio->regs = p;
163	exar_gpio->index = index;
164	exar_gpio->first_pin = first_pin;
165
166	ret = devm_gpiochip_add_data(&pdev->dev,
167				     &exar_gpio->gpio_chip, exar_gpio);
168	if (ret)
169		goto err_destroy;
170
171	platform_set_drvdata(pdev, exar_gpio);
172
173	return 0;
174
175err_destroy:
176	ida_simple_remove(&ida_index, index);
177	mutex_destroy(&exar_gpio->lock);
178	return ret;
179}
180
181static int gpio_exar_remove(struct platform_device *pdev)
182{
183	struct exar_gpio_chip *exar_gpio = platform_get_drvdata(pdev);
184
185	ida_simple_remove(&ida_index, exar_gpio->index);
186	mutex_destroy(&exar_gpio->lock);
187
188	return 0;
189}
190
191static struct platform_driver gpio_exar_driver = {
192	.probe	= gpio_exar_probe,
193	.remove	= gpio_exar_remove,
194	.driver	= {
195		.name = DRIVER_NAME,
196	},
197};
198
199module_platform_driver(gpio_exar_driver);
200
201MODULE_ALIAS("platform:" DRIVER_NAME);
202MODULE_DESCRIPTION("Exar GPIO driver");
203MODULE_AUTHOR("Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>");
204MODULE_LICENSE("GPL");