From 910bd284c39cb52eefcd61651a8278b329be5e5a Mon Sep 17 00:00:00 2001
From: Holger Hans Peter Freyther <holger@freyther.de>
Date: Tue, 28 Jun 2016 08:45:29 +0200
Subject: [PATCH] i2c: Enable i2c and perform bus clear procedure

Help the boot loader and perform a bus clear. U-Boot will try to
read the MAC from the EEPROM and barebox has the complex boot
state stored in it.

In the past we have seen U-boot failing to read from the EEPROM
and let's have one place to initialize it.
---
 board.h   |  2 +-
 davinci.c | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/board.h b/board.h
index d7f896c..84a4bec 100644
--- a/board.h
+++ b/board.h
@@ -39,7 +39,7 @@
 
 #if defined(board_sysmobts_v2)
 #  define PINMUX0_DEFAULT 0x0000000F
-#  define PINMUX1_DEFAULT PINMUX1_UART0 | PINMUX1_UART1
+#  define PINMUX1_DEFAULT PINMUX1_UART0 | PINMUX1_UART1 | PINMUX1_I2C
 #  define NAND_nWP_GPIO 33
 #endif
 
diff --git a/davinci.c b/davinci.c
index e7ed279..d3ea368 100644
--- a/davinci.c
+++ b/davinci.c
@@ -217,6 +217,39 @@ lpsc_tansition(uint8_t module, uint8_t domain, uint8_t state)
 		;
 }
 
+static void
+i2c_init(void)
+{
+	int i;
+
+	// Perform a bus clear. That is the best we can do to
+	// unlock I2C devices that do not have reset signal
+	SYSTEM->PINMUX[1] &= ~PINMUX1_I2C;
+
+	gpio_direction_in(43);          // SCL High
+	waitloop(450);
+	gpio_direction_in(44);          // SDA High
+	waitloop(450);
+
+	gpio_direction_out(43, 0);      // SCL Low
+	waitloop(450);
+	gpio_direction_out(44, 0);      // SDA Low
+	waitloop(450);
+
+	for (i=0; i<9; i++) {
+		gpio_direction_in(43);      // SCL High
+		waitloop(450);
+		gpio_direction_out(43, 0);  // SCL Low
+		waitloop(450);
+	}
+
+	gpio_direction_in(43);          // SCL High
+	waitloop(450);
+	gpio_direction_in(44);          // SDA High
+
+	SYSTEM->PINMUX[1] |= PINMUX1_I2C;
+}
+
 static void
 ivt_init(void)
 {
@@ -716,6 +749,12 @@ davinci_platform_init(char *version, int *nwp_nand)
 	gpio_direction_out(HDD_ENA, 1);
 #endif
 
+	/* Init/Reset I2C */
+#ifdef PINMUX1_DEFAULT
+	if ((PINMUX1_DEFAULT) & PINMUX1_I2C)
+		i2c_init();
+#endif
+
 	/* IRQ Vector Table Setup */
 	ivt_init();