drivers/gpio/gpio-mockup.c

   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
  22 enum 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  */
  32 struct gpio_pin_status {
  33         enum direction dir;
  34         bool value;
  35 };
  36
  37 struct mockup_gpio_controller {
  38         struct gpio_chip gc;
  39         struct gpio_pin_status *stats;
  40 };
  41
  42 static int gpio_mockup_ranges[MAX_GC << 1];
  43 static int gpio_mockup_params_nr;
  44 module_param_array(gpio_mockup_ranges, int, &gpio_mockup_params_nr, 0400);
  45
  46 const char pins_name_start = 'A';
  47
  48 static 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
  55 static 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
  63 static 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
  73 static 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
  81 static 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
  88 static 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;
 116 err:
 117         dev_err(dev, "gpio<%d..%d> add failed!", base, base + ngpio);
 118         return ret;
 119 }
 120
 121 static 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
 171 static struct platform_driver mockup_gpio_driver = {
 172         .driver = {
 173                    .name = GPIO_NAME,
 174                    },
 175         .probe = mockup_gpio_probe,
 176 };
 177
 178 static struct platform_device *pdev;
 179 static 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
 202 static void __exit mock_device_exit(void)
 203 {
 204         platform_driver_unregister(&mockup_gpio_driver);
 205         platform_device_unregister(pdev);
 206 }
 207
 208 module_init(mock_device_init);
 209 module_exit(mock_device_exit);
 210
 211 MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>");
 212 MODULE_AUTHOR("Bamvor Jian Zhang <bamvor.zhangjian@linaro.org>");
 213 MODULE_DESCRIPTION("GPIO Testing driver");
 214 MODULE_LICENSE("GPL v2");