diff options
| -rw-r--r-- | 1/fopdrv.c | 25 |
1 files changed, 23 insertions, 2 deletions
@@ -3,17 +3,37 @@ #include "fopdrv.h" #include "config.h" +bool printed = false; + // driver/char/mem.c read_null (/dev/null) ssize_t fop_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { printk("%s(<file>, <buf>, %u, <ppos>)\n", __PRETTY_FUNCTION__, count); - return 0; + + if (count < 2) return 0; + if (printed) return 0; + + ti_am335x_word_t* gpio1 = ioremap(TI_AM335X_GPIO1_ADDR, GPIO_REG_SIZE); + barrier(); + + ti_am335x_word_t gpio = ioread32(gpio1 + GPIO_DATAIN); rmb(); + bool on = (gpio & (1<<PIN)) > 0; + + char output[10]; + snprintf(output, 10, "%d\n", on); + + if (copy_to_user(buf, output + *ppos, 2)) + return -EFAULT; + *ppos += 2; + printed = true; + return 2; } ssize_t fop_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { printk("%s(<file>, <buf>, %u, <ppos>)\n", __PRETTY_FUNCTION__, count); // only allow single character as input - if (count != 1) return count; + if (count < 1) return count; + if (count > 2) return count; // copy buffer for reading (see [kernel-labs-chrdev] in ../readme.md) char input_buf[10]; @@ -39,6 +59,7 @@ ssize_t fop_write(struct file *file, const char __user *buf, size_t count, loff_ int fop_open(struct inode * inode, struct file * file) { printk("%s(<inode>, <file>)\n", __PRETTY_FUNCTION__); + printed = false; return 0; // 0 seems to be a safe return value as it's used in driver/char/mem.c. The // manual page for open(2) says that the system call returns a nonnegative |