From 6926a88695ce2e9fca51e01a1bf6fded3e4cbcca Mon Sep 17 00:00:00 2001 From: lonkaars Date: Sun, 12 May 2024 15:15:35 +0200 Subject: fix echo input + cat output --- 1/fopdrv.c | 25 +++++++++++++++++++++++-- 1 file changed, 23 insertions(+), 2 deletions(-) diff --git a/1/fopdrv.c b/1/fopdrv.c index d048f15..18a1d35 100644 --- a/1/fopdrv.c +++ b/1/fopdrv.c @@ -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(, , %u, )\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< 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(, , %u, )\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(, )\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 -- cgit v1.2.3