OMAP3: Beagle: Add board revision detection

With BeagleBoard revision C some HW changes are introduced (e.g. PinMUX)
which might need different software handling. For this, GPIO pin 171 (GPIO
module 6, offset 11) can be used to check for board revision. If this pin
is low, we have a rev C board. Else it must be a revision Ax or Bx board.

To handle board differences you can call function beagle_get_revision().
E.g.:

if (beagle_get_revision()) {

/* do special revision C stuff here */

}

Signed-off-by: Dirk Behme <dirk.behme@googlemail.com>

board/omap3/beagle/beagle.c

@@ -36,6 +36,8 @@
 #include <asm/mach-types.h>
 #include "beagle.h"
 
+static int beagle_revision_c;
+
 /******************************************************************************
  * Routine: board_init
  * Description: Early hardware init.
@@ -54,6 +56,43 @@ int board_init(void)
 }
 
 /******************************************************************************
+ * Routine: beagle_get_revision
+ * Description: Return revision of the BeagleBoard this code is running on.
+ *              If it is a revision Ax/Bx board, this function returns 0,
+ *              on a revision C board you will get a 1.
+ *****************************************************************************/
+int beagle_get_revision(void)
+{
+	return beagle_revision_c;
+}
+
+/******************************************************************************
+ * Routine: beagle_identify
+ * Description: Detect if we are running on a Beagle revision Ax/Bx or
+ *              Cx. This can be done by GPIO_171. If this is low, we are
+ *              running on a revision C board.
+ *****************************************************************************/
+void beagle_identify(void)
+{
+	gpio_t *gpio6_base = (gpio_t *)OMAP34XX_GPIO6_BASE;
+
+	/* Configure GPIO 171 as input */
+	writel(readl(&gpio6_base->oe) | GPIO11, &gpio6_base->oe);
+
+	/* Get value of GPIO 171 */
+	beagle_revision_c = readl(&gpio6_base->datain) & BOARD_REVISION_MASK;
+
+	printf("Board revision ");
+	if (beagle_revision_c) {
+		printf("Ax/Bx\n");
+		beagle_revision_c = 0;
+	} else {
+		printf("C\n");
+		beagle_revision_c = 1;
+	}
+}
+
+/******************************************************************************
  * Routine: misc_init_r
  * Description: Configure board specific parts
  *****************************************************************************/
@@ -75,6 +114,8 @@ int misc_init_r(void)
 	writel(GPIO31 | GPIO30 | GPIO29 | GPIO28 | GPIO22 | GPIO21 |
 		GPIO15 | GPIO14 | GPIO13 | GPIO12, &gpio5_base->setdataout);
 
+	beagle_identify();
+
 	return 0;
 }
 

board/omap3/beagle/beagle.h

@@ -36,6 +36,8 @@ const omap3_sysinfo sysinfo = {
 #endif
 };
 
+#define BOARD_REVISION_MASK	(0x1 << 11)
+
 /*
  * IEN  - Input Enable
  * IDIS - Input Disable

include/asm-arm/arch-omap3/omap3.h

@@ -97,7 +97,8 @@ typedef struct s32ktimer {
 typedef struct gpio {
 	unsigned char res1[0x34];
 	unsigned int oe;		/* 0x34 */
-	unsigned char res2[0x58];
+	unsigned int datain;		/* 0x38 */
+	unsigned char res2[0x54];
 	unsigned int cleardataout;	/* 0x90 */
 	unsigned int setdataout;	/* 0x94 */
 } gpio_t;