| 1 | /* |
| 2 | * character device wrapper for generic gpio layer |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License as published by |
| 6 | * the Free Software Foundation; either version 2 of the License, or |
| 7 | * (at your option) any later version. |
| 8 | * |
| 9 | * This program is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | * GNU General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with this program; if not, write to the Free Software |
| 16 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA02111-1307USA |
| 17 | * |
| 18 | * Feedback, Bugs... blogic@openwrt.org |
| 19 | * |
| 20 | * dpg 20100106 |
| 21 | */ |
| 22 | |
| 23 | #include <linux/module.h> |
| 24 | #include <linux/errno.h> |
| 25 | #include <linux/init.h> |
| 26 | #include <asm/uaccess.h> |
| 27 | #include <asm/io.h> |
| 28 | #include <asm/gpio.h> |
| 29 | #include <asm/atomic.h> |
| 30 | #include <linux/init.h> |
| 31 | #include <linux/genhd.h> |
| 32 | #include <linux/device.h> |
| 33 | #include <linux/platform_device.h> |
| 34 | #include <linux/gpio_dev.h> |
| 35 | #include <linux/fs.h> |
| 36 | |
| 37 | #define DRVNAME "gpiodev" |
| 38 | #define DEVNAME "gpio" |
| 39 | |
| 40 | static int dev_major; |
| 41 | static struct class *gpiodev_class; |
| 42 | |
| 43 | |
| 44 | /* third argument of user space ioctl ('arg' here) contains the <pin> */ |
| 45 | static int |
| 46 | gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg) |
| 47 | { |
| 48 | int retval = 0; |
| 49 | |
| 50 | switch (cmd) |
| 51 | { |
| 52 | case GPIO_GET: |
| 53 | retval = gpio_get_value(arg); |
| 54 | break; |
| 55 | case GPIO_SET: |
| 56 | gpio_set_value(arg, 1); |
| 57 | break; |
| 58 | case GPIO_CLEAR: |
| 59 | gpio_set_value(arg, 0); |
| 60 | break; |
| 61 | case GPIO_DIR_IN: |
| 62 | retval = gpio_direction_input(arg); |
| 63 | break; |
| 64 | case GPIO_DIR_OUT: |
| 65 | retval = gpio_direction_output(arg, 0); |
| 66 | break; |
| 67 | case GPIO_DIR_HIGH: |
| 68 | retval = gpio_direction_output(arg, 1); |
| 69 | break; |
| 70 | case GPIO_REQUEST: |
| 71 | /* should be first ioctl operation on <pin> */ |
| 72 | retval = gpio_request(arg, DRVNAME); |
| 73 | break; |
| 74 | case GPIO_FREE: |
| 75 | /* should be last ioctl operation on <pin> */ |
| 76 | /* may be needed first if previous user missed this ioctl */ |
| 77 | gpio_free(arg); |
| 78 | break; |
| 79 | case GPIO_CAN_SLEEP: |
| 80 | retval = gpio_cansleep(arg); |
| 81 | break; |
| 82 | default: |
| 83 | retval = -EINVAL; |
| 84 | /* = -ENOTTY; // correct return but ... */ |
| 85 | break; |
| 86 | } |
| 87 | return retval; |
| 88 | } |
| 89 | |
| 90 | /* Allow co-incident opens */ |
| 91 | static int |
| 92 | gpio_open(struct inode *inode, struct file *file) |
| 93 | { |
| 94 | int result = 0; |
| 95 | unsigned int dev_minor = MINOR(inode->i_rdev); |
| 96 | |
| 97 | if (dev_minor != 0) |
| 98 | { |
| 99 | printk(KERN_ERR DRVNAME ": trying to access unknown minor device -> %d\n", dev_minor); |
| 100 | result = -ENODEV; |
| 101 | goto out; |
| 102 | } |
| 103 | out: |
| 104 | return result; |
| 105 | } |
| 106 | |
| 107 | static int |
| 108 | gpio_close(struct inode * inode, struct file * file) |
| 109 | { |
| 110 | /* could track all <pin>s requested by this fd and gpio_free() |
| 111 | * them here |
| 112 | */ |
| 113 | return 0; |
| 114 | } |
| 115 | |
| 116 | struct file_operations gpio_fops = { |
| 117 | unlocked_ioctl: gpio_ioctl, |
| 118 | open: gpio_open, |
| 119 | release: gpio_close |
| 120 | }; |
| 121 | |
| 122 | static int |
| 123 | gpio_probe(struct platform_device *dev) |
| 124 | { |
| 125 | int result = 0; |
| 126 | |
| 127 | dev_major = register_chrdev(0, DEVNAME, &gpio_fops); |
| 128 | if (!dev_major) |
| 129 | { |
| 130 | printk(KERN_ERR DRVNAME ": Error whilst opening %s \n", DEVNAME); |
| 131 | result = -ENODEV; |
| 132 | goto out; |
| 133 | } |
| 134 | gpiodev_class = class_create(THIS_MODULE, DRVNAME); |
| 135 | device_create(gpiodev_class, NULL, MKDEV(dev_major, 0), dev, DEVNAME); |
| 136 | printk(KERN_INFO DRVNAME ": gpio device registered with major %d\n", dev_major); |
| 137 | out: |
| 138 | return result; |
| 139 | } |
| 140 | |
| 141 | static int |
| 142 | gpio_remove(struct platform_device *dev) |
| 143 | { |
| 144 | device_destroy(gpiodev_class, MKDEV(dev_major, 0)); |
| 145 | class_destroy(gpiodev_class); |
| 146 | unregister_chrdev(dev_major, DEVNAME); |
| 147 | return 0; |
| 148 | } |
| 149 | |
| 150 | static struct |
| 151 | platform_driver gpio_driver = { |
| 152 | .probe = gpio_probe, |
| 153 | .remove = gpio_remove, |
| 154 | .driver = { |
| 155 | .name = "GPIODEV", |
| 156 | .owner = THIS_MODULE, |
| 157 | }, |
| 158 | }; |
| 159 | |
| 160 | static int __init |
| 161 | gpio_mod_init(void) |
| 162 | { |
| 163 | int ret = platform_driver_register(&gpio_driver); |
| 164 | if (ret) |
| 165 | printk(KERN_INFO DRVNAME ": Error registering platfom driver!\n"); |
| 166 | |
| 167 | return ret; |
| 168 | } |
| 169 | |
| 170 | static void __exit |
| 171 | gpio_mod_exit(void) |
| 172 | { |
| 173 | platform_driver_unregister(&gpio_driver); |
| 174 | } |
| 175 | |
| 176 | module_init (gpio_mod_init); |
| 177 | module_exit (gpio_mod_exit); |
| 178 | |
| 179 | MODULE_LICENSE("GPL"); |
| 180 | MODULE_AUTHOR("John Crispin / OpenWrt +"); |
| 181 | MODULE_DESCRIPTION("Character device for for generic gpio api"); |
| 182 | |
