implement simple printf "0" or "1" > /dev/lork input + add some registers to config.h

2 files changed, 29 insertions, 2 deletions

diff --git a/1/config.h b/1/config.h
index 7302134..6326354 100644
--- a/1/config.h
+++ b/1/config.h
@@ -2,3 +2,14 @@
 
 #define DRV_NAME "lork"
 
+#include <linux/types.h>
+
+// values from <https://www.ti.com/lit/ug/spruh73q/spruh73q.pdf>
+
+typedef uint32_t ti_am335x_word_t;
+
+// p. 180: "Control Module"
+#define TI_AM335X_CM_ADDR ((ti_am335x_word_t*) 0x44E1_0000)
+// p. 1459: "conf_gpmc_a3"
+#define TI_AM335X_CM_GPMC_A3_ADDR ((ti_am335x_word_t*) TI_AM3358_CM_ADDR + 0x84Ch)
+
diff --git a/1/fopdrv.c b/1/fopdrv.c
index 2c74fea..e0ad41c 100644
--- a/1/fopdrv.c
+++ b/1/fopdrv.c
@@ -2,13 +2,29 @@
 
 // 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>, %lu, <ppos>)\n", __PRETTY_FUNCTION__, count);
+	printk("%s(<file>, <buf>, %u, <ppos>)\n", __PRETTY_FUNCTION__, count);
 	return 0;
 }
 
 // driver/char/mem.c write_null
 ssize_t fop_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) {
-	printk("%s(<file>, <buf>, %lu, <ppos>)\n", __PRETTY_FUNCTION__, count);
+	printk("%s(<file>, <buf>, %u, <ppos>)\n", __PRETTY_FUNCTION__, count);
+
+	// only allow single character as input
+	if (count != 1) 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;
+
+	if (input_buf[0] == '0') {
+		printk("TODO: TURN OFF OUTPUT\n");
+	}
+	if (input_buf[0] == '1') {
+		printk("TODO: TURN ON OUTPUT\n");
+	}
+
 	return count;
 }