diff options
Diffstat (limited to 'driver/fopdrv.c')
-rw-r--r-- | driver/fopdrv.c | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/driver/fopdrv.c b/driver/fopdrv.c new file mode 100644 index 0000000..18a1d35 --- /dev/null +++ b/driver/fopdrv.c @@ -0,0 +1,76 @@ +#include <linux/io.h> + +#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); + + 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 > 2) return count; + + // copy buffer for reading (see [kernel-labs-chrdev] in ../readme.md) + char input_buf[10]; + if (copy_from_user(input_buf + *ppos, buf, count)) + return -EFAULT; + + ti_am335x_word_t* gpio1 = ioremap(TI_AM335X_GPIO1_ADDR, GPIO_REG_SIZE); + barrier(); + + if (input_buf[0] == '0') { + printk("TODO: TURN OFF OUTPUT\n"); + iowrite32((1<<PIN), gpio1 + GPIO_CLEARDATAOUT); wmb(); + } + if (input_buf[0] == '1') { + printk("TODO: TURN ON OUTPUT\n"); + iowrite32((1<<PIN), gpio1 + GPIO_SETDATAOUT); wmb(); + } + + iounmap(gpio1); + + return count; +} + +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 + // integer representing the file descriptor on success, but it does not + // appears to be required. +} + +int fop_release(struct inode * inode, struct file * file) { + printk("%s(<inode>, <file>)\n", __PRETTY_FUNCTION__); + return 0; + // same as above, but found in driver/char/lp.c +} + + |