rx2-lkm/rx2.c

#include <linux/fs.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/gpio.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <asm/uaccess.h>
#include <asm/delay.h>

typedef struct { char *key; u8 value; } t_command;

static t_command commands_table[] = {
  { "ENDCODE",         4},
  { "FORWARD",        10},
  { "FORWARD_TURBO",  16},
  { "TURBO",          22},
  { "FORWARD_LEFT",   28},
  { "FORWARD_RIGHT",  34},
  { "BACKWARD",       40},
  { "BACKWARD_RIGHT", 46},
  { "BACKWARD_LEFT",  52},
  { "LEFT",           58},
  { "RIGHT",          64}
};

static ssize_t rx2_dev_write(struct file *filep, const char *buffer, size_t len, loff_t *offset);

static const struct file_operations rx2_fops = {
  .owner = THIS_MODULE,
  .write = rx2_dev_write
};

static struct miscdevice rx2_dev = {
  MISC_DYNAMIC_MINOR,
  "rx2",
  &rx2_fops
};

static int gpio = -1;

static void rx2_send_command(u8 command) {
  int w = 0;

  for(w = 0; w < 4; w++) {
    gpio_set_value(gpio, 1);
    udelay(1200);
    gpio_set_value(gpio, 0);
    udelay(400);
  }

  for(w = 0; w < command; w++) {
    gpio_set_value(gpio, 1);
    udelay(400);
    gpio_set_value(gpio, 0);
    udelay(400);
  }
}

static ssize_t rx2_dev_write(struct file *filep, const char *buffer, size_t len, loff_t *offset) {
  u8 n;
  for(n = 0; n < sizeof(commands_table) / sizeof(t_command); n++) {
    if(strcmp(commands_table[n].key, buffer) == 0) {
      printk(KERN_INFO "%s %i\n", commands_table[n].key, commands_table[n].value);
      rx2_send_command(commands_table[n].value);
      break;
    }
  }
  return len;
}

static int __init rx2_init(void) {
  int ret;
  
  if(!gpio_is_valid(gpio)) {
    printk(KERN_ERR "rx2: invalid gpio\n");
    return -EINVAL;
  }
  ret = gpio_request(gpio, "ant");
  if(ret) {
    if (ret == -EINVAL)
      ret = -EPROBE_DEFER;
    return ret;
  }
  printk(KERN_INFO "rx2: ant on gpio: %i\n",gpio);
  gpio_direction_output(gpio, 0);

  ret = misc_register(&rx2_dev);
  
  if(ret) {
    printk(KERN_ERR "Unable to register rx2 device\n");
    gpio_free(gpio);
    return ret;
  }          
  return ret;
}

static void __exit rx2_exit(void) {
  gpio_free(gpio);
  misc_deregister(&rx2_dev);
}

module_init(rx2_init);
module_exit(rx2_exit);

module_param(gpio, int, 0444);
MODULE_PARM_DESC(gpio, "Guess what");

MODULE_LICENSE("GPL");
MODULE_AUTHOR("encrypt <encrypt@labr.xyz>");
MODULE_DESCRIPTION("Stupid driver for RX2 ic");
MODULE_VERSION("0.1");