rename folders

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
+}
+
+