diff options
Diffstat (limited to 'target/linux/generic-2.6/files/drivers/char/gpio_dev.c')
| -rw-r--r-- | target/linux/generic-2.6/files/drivers/char/gpio_dev.c | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/target/linux/generic-2.6/files/drivers/char/gpio_dev.c b/target/linux/generic-2.6/files/drivers/char/gpio_dev.c new file mode 100644 index 0000000000..48ef76f8a9 --- /dev/null +++ b/target/linux/generic-2.6/files/drivers/char/gpio_dev.c @@ -0,0 +1,201 @@ +/* + * character device wrapper for generic gpio layer + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA02111-1307USA + * + * Feedback, Bugs... blogic@openwrt.org + * + */ + +#include <linux/module.h> +#include <linux/errno.h> +#include <linux/init.h> +#include <asm/uaccess.h> +#include <asm/io.h> +#include <asm/gpio.h> +#include <asm/atomic.h> +#include <linux/init.h> +#include <linux/genhd.h> +#include <linux/device.h> +#include <linux/platform_device.h> +#include <linux/gpio_dev.h> + +#define DRVNAME "gpiodev" +#define DEVNAME "gpio" + +static int dev_major; +static unsigned int gpio_access_mask; +static struct class *gpio_class; + +/* Counter is 1, if the device is not opened and zero (or less) if opened. */ +static atomic_t gpio_open_cnt = ATOMIC_INIT(1); + +static int +gpio_ioctl(struct inode * inode, struct file * file, unsigned int cmd, unsigned long arg) +{ + int retval = 0; + + if (((1 << arg) & gpio_access_mask) != (1 << arg)) + { + retval = -EINVAL; + goto out; + } + + switch (cmd) + { + case GPIO_GET: + retval = gpio_get_value(arg); + break; + + case GPIO_SET: + gpio_set_value(arg, 1); + break; + + case GPIO_CLEAR: + gpio_set_value(arg, 0); + break; + + case GPIO_DIR_IN: + gpio_direction_input(arg); + break; + + case GPIO_DIR_OUT: + gpio_direction_output(arg, 0); + break; + + default: + retval = -EINVAL; + break; + } + +out: + return retval; +} + +static int +gpio_open(struct inode *inode, struct file *file) +{ + int result = 0; + unsigned int dev_minor = MINOR(inode->i_rdev); + + if (dev_minor != 0) + { + printk(KERN_ERR DRVNAME ": trying to access unknown minor device -> %d\n", dev_minor); + result = -ENODEV; + goto out; + } + + /* FIXME: We should really allow multiple applications to open the device + * at the same time, as long as the apps access different IO pins. + * The generic gpio-registration functions can be used for that. + * Two new IOCTLs have to be introduced for that. Need to check userspace + * compatibility first. --mb */ + if (!atomic_dec_and_test(&gpio_open_cnt)) { + atomic_inc(&gpio_open_cnt); + printk(KERN_ERR DRVNAME ": Device with minor ID %d already in use\n", dev_minor); + result = -EBUSY; + goto out; + } + +out: + return result; +} + +static int +gpio_close(struct inode * inode, struct file * file) +{ + smp_mb__before_atomic_inc(); + atomic_inc(&gpio_open_cnt); + + return 0; +} + +struct file_operations gpio_fops = { + ioctl: gpio_ioctl, + open: gpio_open, + release: gpio_close +}; + +static int +gpio_probe(struct platform_device *dev) +{ + int result = 0; + + dev_major = register_chrdev(0, DEVNAME, &gpio_fops); + if (!dev_major) + { + printk(KERN_ERR DRVNAME ": Error whilst opening %s \n", DEVNAME); + result = -ENODEV; + goto out; + } + + gpio_class = class_create(THIS_MODULE, DEVNAME); + class_device_create(gpio_class, NULL, MKDEV(dev_major, 0), NULL, DEVNAME); + + printk(KERN_INFO DRVNAME ": gpio device registered with major %d\n", dev_major); + + if (dev->num_resources != 1) + { + printk(KERN_ERR DRVNAME ": device may only have 1 resource\n"); + result = -ENODEV; + goto out; + } + + gpio_access_mask = dev->resource[0].start; + + printk(KERN_INFO DRVNAME ": gpio platform device registered with access mask %08X\n", gpio_access_mask); +out: + return result; +} + +static int +gpio_remove(struct platform_device *dev) +{ + unregister_chrdev(dev_major, DEVNAME); + return 0; +} + +static struct +platform_driver gpio_driver = { + .probe = gpio_probe, + .remove = gpio_remove, + .driver = { + .name = "GPIODEV", + .owner = THIS_MODULE, + }, +}; + +static int __init +gpio_mod_init(void) +{ + int ret = platform_driver_register(&gpio_driver); + if (ret) + printk(KERN_INFO DRVNAME ": Error registering platfom driver!"); + + return ret; +} + +static void __exit +gpio_mod_exit(void) +{ + platform_driver_unregister(&gpio_driver); +} + +module_init (gpio_mod_init); +module_exit (gpio_mod_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("John Crispin / OpenWrt"); +MODULE_DESCRIPTION("Character device for for generic gpio api"); |