Document devmem2 tests better

Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>

1 files changed, 14 insertions, 7 deletions

diff --git a/tests.c b/tests.c
index 32fef82..3d89b67 100644
--- a/tests.c
+++ b/tests.c
@@ -111,17 +111,20 @@ static int test_flash_with_devmem2(int debug, char *devmem, int fd,
 {
 	int rc;
 
-	/* On Parabola with the nonfree u-boot and the Replicant 11 kernel,
-	 * the gpio value register is 0x0 after boot, so I hope that it is safe
-	 * to set it to 0x0 too on Replicant 6, even if after boot, its value
-	 * is 0x1.
-	 * We also used the default values after booting Parabola for the gpio
-	 * direction register.
+	/* Default values at boot:
+	 * +--------------+------------+----------+
+	 * | Distribution | Address    | Value[1] |
+	 * +--------------+------------+----------+
+	 * | Parabola     | 0x11400260 | 0x2000   |
+	 * | Parabola     | 0x11400264 | 0x0000   |
+	 * +--------------+------------+----------+
+	 * [1]obtained with devmem2 <address> w
 	 */
 
 	/* Set the GPIO to input */
 	if (debug)
 		printf("       Starting devmem2 GPIO input test\n");
+	/* GPJ1CON[4:7] with bit 4 to 7 at 0 => 0xnn0n (n == don't care) */
 	rc = run_command(debug, "devmem2 0x11400260 w 0x2000");
 	assert(rc == 0);
 	rc = gpio_get_direction(devmem, fd, page_size, "gpj1", 1);
@@ -131,13 +134,15 @@ static int test_flash_with_devmem2(int debug, char *devmem, int fd,
 	/* Set the GPIO to output */
 	if (debug)
 		printf("       Starting devmem2 GPIO output test\n");
-	rc = run_command(debug, "devmem2 0x11400260 w 0x2002");
+	/* GPJ1CON[4:7] with bit 1 @ 1 and the rest at 0 => 1<<5 == 0x20 */
+	rc = run_command(debug, "devmem2 0x11400260 w 0x2020");
 	assert(rc == 0);
 	rc = gpio_get_direction(devmem, fd, page_size, "gpj1", 1);
 	assert (rc == GPIO_OUTPUT);
 	printf("[ OK ] devmem2 GPIO output test\n");
 
 	/* Set the pin LOW */
+	/* GPJ1DAT[1] == 0 */
 	if (debug)
 		printf("       Starting devmem2 GPIO output low test\n");
 	rc = run_command(debug, "devmem2 0x11400264 w 0");
@@ -147,6 +152,7 @@ static int test_flash_with_devmem2(int debug, char *devmem, int fd,
 	printf("[ OK ] devmem2 GPIO output low test\n");
 
 	/* Set the pin HIGH */
+	/* GPJ1DAT[1] == 1 => 1<<1 == 2 */
 	if (debug)
 		printf("       Starting devmem2 GPIO output high test\n");
 	rc = run_command(debug, "devmem2 0x11400264 w 2");
@@ -156,6 +162,7 @@ static int test_flash_with_devmem2(int debug, char *devmem, int fd,
 	printf("[ OK ] devmem2 GPIO output high test\n");
 
 	/* Set it to low again */
+	/* GPJ1DAT[1] == 0 */
 	if (debug)
 		printf("       Starting devmem2 GPIO output low test\n");
 	rc = run_command(debug, "devmem2 0x11400264 w 0");