1/*
  2 * GPIO Testing Device Driver
  3 *
  4 * Copyright (C) 2014  Kamlakant Patel <kamlakant.patel@broadcom.com>
  5 * Copyright (C) 2015-2016  Bamvor Jian Zhang <bamvor.zhangjian@linaro.org>
  6 *
  7 * This program is free software; you can redistribute  it and/or modify it
  8 * under  the terms of  the GNU General  Public License as published by the
  9 * Free Software Foundation;  either version 2 of the  License, or (at your
 10 * option) any later version.
 11 *
 12 */
 13
 14#include <linux/init.h>
 15#include <linux/module.h>
 16#include <linux/gpio/driver.h>
 17#include <linux/platform_device.h>
 18
 19#define GPIO_NAME	"gpio-mockup"
 20#define	MAX_GC		10
 21
 22enum direction {
 23	OUT,
 24	IN
 25};
 26
 27/*
 28 * struct gpio_pin_status - structure describing a GPIO status
 29 * @dir:       Configures direction of gpio as "in" or "out", 0=in, 1=out
 30 * @value:     Configures status of the gpio as 0(low) or 1(high)
 31 */
 32struct gpio_pin_status {
 33	enum direction dir;
 34	bool value;
 35};
 36
 37struct mockup_gpio_controller {
 38	struct gpio_chip gc;
 39	struct gpio_pin_status *stats;
 40};
 41
 42static int gpio_mockup_ranges[MAX_GC << 1];
 43static int gpio_mockup_params_nr;
 44module_param_array(gpio_mockup_ranges, int, &gpio_mockup_params_nr, 0400);
 45
 46const char pins_name_start = 'A';
 47
 48static int mockup_gpio_get(struct gpio_chip *gc, unsigned int offset)
 49{
 50	struct mockup_gpio_controller *cntr = gpiochip_get_data(gc);
 51
 52	return cntr->stats[offset].value;
 53}
 54
 55static void mockup_gpio_set(struct gpio_chip *gc, unsigned int offset,
 56			    int value)
 57{
 58	struct mockup_gpio_controller *cntr = gpiochip_get_data(gc);
 59
 60	cntr->stats[offset].value = !!value;
 61}
 62
 63static int mockup_gpio_dirout(struct gpio_chip *gc, unsigned int offset,
 64			      int value)
 65{
 66	struct mockup_gpio_controller *cntr = gpiochip_get_data(gc);
 67
 68	mockup_gpio_set(gc, offset, value);
 69	cntr->stats[offset].dir = OUT;
 70	return 0;
 71}
 72
 73static int mockup_gpio_dirin(struct gpio_chip *gc, unsigned int offset)
 74{
 75	struct mockup_gpio_controller *cntr = gpiochip_get_data(gc);
 76
 77	cntr->stats[offset].dir = IN;
 78	return 0;
 79}
 80
 81static int mockup_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
 82{
 83	struct mockup_gpio_controller *cntr = gpiochip_get_data(gc);
 84
 85	return cntr->stats[offset].dir;
 86}
 87
 88static int mockup_gpio_add(struct device *dev,
 89			   struct mockup_gpio_controller *cntr,
 90			   const char *name, int base, int ngpio)
 91{
 92	int ret;
 93
 94	cntr->gc.base = base;
 95	cntr->gc.ngpio = ngpio;
 96	cntr->gc.label = name;
 97	cntr->gc.owner = THIS_MODULE;
 98	cntr->gc.parent = dev;
 99	cntr->gc.get = mockup_gpio_get;
100	cntr->gc.set = mockup_gpio_set;
101	cntr->gc.direction_output = mockup_gpio_dirout;
102	cntr->gc.direction_input = mockup_gpio_dirin;
103	cntr->gc.get_direction = mockup_gpio_get_direction;
104	cntr->stats = devm_kzalloc(dev, sizeof(*cntr->stats) * cntr->gc.ngpio,
105				   GFP_KERNEL);
106	if (!cntr->stats) {
107		ret = -ENOMEM;
108		goto err;
109	}
110	ret = devm_gpiochip_add_data(dev, &cntr->gc, cntr);
111	if (ret)
112		goto err;
113
114	dev_info(dev, "gpio<%d..%d> add successful!", base, base + ngpio);
115	return 0;
116err:
117	dev_err(dev, "gpio<%d..%d> add failed!", base, base + ngpio);
118	return ret;
119}
120
121static int mockup_gpio_probe(struct platform_device *pdev)
122{
123	struct device *dev = &pdev->dev;
124	struct mockup_gpio_controller *cntr;
125	int ret;
126	int i;
127	int base;
128	int ngpio;
129	char chip_name[sizeof(GPIO_NAME) + 3];
130
131	if (gpio_mockup_params_nr < 2)
132		return -EINVAL;
133
134	cntr = devm_kzalloc(dev, sizeof(*cntr) * (gpio_mockup_params_nr >> 1),
135			    GFP_KERNEL);
136	if (!cntr)
137		return -ENOMEM;
138
139	platform_set_drvdata(pdev, cntr);
140
141	for (i = 0; i < gpio_mockup_params_nr >> 1; i++) {
142		base = gpio_mockup_ranges[i * 2];
143		if (base == -1)
144			ngpio = gpio_mockup_ranges[i * 2 + 1];
145		else
146			ngpio = gpio_mockup_ranges[i * 2 + 1] - base;
147
148		if (ngpio >= 0) {
149			sprintf(chip_name, "%s-%c", GPIO_NAME,
150				pins_name_start + i);
151			ret = mockup_gpio_add(dev, &cntr[i],
152					      chip_name, base, ngpio);
153		} else {
154			ret = -1;
155		}
156		if (ret) {
157			if (base < 0)
158				dev_err(dev, "gpio<%d..%d> add failed\n",
159					base, ngpio);
160			else
161				dev_err(dev, "gpio<%d..%d> add failed\n",
162					base, base + ngpio);
163
164			return ret;
165		}
166	}
167
168	return 0;
169}
170
171static struct platform_driver mockup_gpio_driver = {
172	.driver = {
173		   .name = GPIO_NAME,
174		   },
175	.probe = mockup_gpio_probe,
176};
177
178static struct platform_device *pdev;
179static int __init mock_device_init(void)
180{
181	int err;
182
183	pdev = platform_device_alloc(GPIO_NAME, -1);
184	if (!pdev)
185		return -ENOMEM;
186
187	err = platform_device_add(pdev);
188	if (err) {
189		platform_device_put(pdev);
190		return err;
191	}
192
193	err = platform_driver_register(&mockup_gpio_driver);
194	if (err) {
195		platform_device_unregister(pdev);
196		return err;
197	}
198
199	return 0;
200}
201
202static void __exit mock_device_exit(void)
203{
204	platform_driver_unregister(&mockup_gpio_driver);
205	platform_device_unregister(pdev);
206}
207
208module_init(mock_device_init);
209module_exit(mock_device_exit);
210
211MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>");
212MODULE_AUTHOR("Bamvor Jian Zhang <bamvor.zhangjian@linaro.org>");
213MODULE_DESCRIPTION("GPIO Testing driver");
214MODULE_LICENSE("GPL v2");