From cdc3fbf2cfe5a14c04d3a1454aef98d8be73f201 Mon Sep 17 00:00:00 2001
From: Randall Spangler <rspangler@chromium.org>
Date: Mon, 23 Jan 2012 14:53:20 -0800
Subject: [PATCH] Calibrate internal oscillator using hibernate clock

This works around a chip errata where the internal oscillator on early
EC parts (as used on proto0) is untrimmed.

Signed-off-by: Randall Spangler <rspangler@chromium.org>

BUG=chrome-os-partner:7693
TEST=if it runs, it works

Change-Id: Ie82a524543f4cf25efd0de7998dbdae103bd126b
---
 chip/lm4/clock.c     |  8 ++++++++
 chip/lm4/registers.h |  4 +++-
 common/main.c        | 15 ++++++++-------
 3 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/chip/lm4/clock.c b/chip/lm4/clock.c
index c9afa57760..fcf0da99e1 100644
--- a/chip/lm4/clock.c
+++ b/chip/lm4/clock.c
@@ -169,6 +169,14 @@ static void clock_init_pll(uint32_t value)
 
 	/* Enable main and precision internal oscillators */
 	LM4_SYSTEM_RCC &= ~0x3;
+
+	/* Perform an auto calibration of the internal oscillator, using the
+	 * 32.768KHz hibernate clock. */
+	/* TODO: (crosbug.com/p/7693) This is only needed on early chips which
+	 * aren't factory trimmed. */
+	LM4_SYSTEM_PIOSCCAL = 0x80000000;
+	LM4_SYSTEM_PIOSCCAL = 0x80000200;
+
 	/* wait 1 million CPU cycles */
 	wait_cycles(512 * 1024);
 
diff --git a/chip/lm4/registers.h b/chip/lm4/registers.h
index ac7f21bd95..0e8b341a36 100644
--- a/chip/lm4/registers.h
+++ b/chip/lm4/registers.h
@@ -1,4 +1,4 @@
-/* Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
+/* Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  *
@@ -160,6 +160,8 @@ static inline int lm4_fan_addr(int ch, int offset)
 #define LM4_SYSTEM_RESC        LM4REG(0x400fe05c)
 #define LM4_SYSTEM_RCC         LM4REG(0x400fe060)
 #define LM4_SYSTEM_RCC2        LM4REG(0x400fe070)
+#define LM4_SYSTEM_PIOSCCAL    LM4REG(0x400fe150)
+#define LM4_SYSTEM_PIOSCSTAT   LM4REG(0x400fe154)
 #define LM4_SYSTEM_PLLSTAT     LM4REG(0x400fe168)
 #define LM4_SYSTEM_RCGCWD      LM4REG(0x400fe600)
 #define LM4_SYSTEM_RCGCTIMER   LM4REG(0x400fe604)
diff --git a/common/main.c b/common/main.c
index e400dfde7d..30faa87066 100644
--- a/common/main.c
+++ b/common/main.c
@@ -1,9 +1,8 @@
-/* Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
+/* Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
- * Copyright 2011 Google Inc.
  *
- * Example of EC main loop
+ * Main routine for Chrome EC
  */
 
 #include "registers.h"
@@ -36,6 +35,7 @@
 #include "usb_charge.h"
 
 /* example task blinking the user LED */
+/* TODO: This also kicks the watchdog, so MUST be present! */
 void UserLedBlink(void)
 {
 	while (1) {
@@ -58,6 +58,11 @@ int main(void)
 	/* Configure the pin multiplexers */
 	configure_board();
 	jtag_pre_init();
+
+	/* Initialize the system module.  This enables the hibernate clock
+	 * source we need to calibrate the internal oscillator. */
+	system_pre_init();
+
 	/* Set the CPU clocks / PLLs */
 	clock_init();
 
@@ -65,13 +70,9 @@ int main(void)
 	 * another image if necessary.  This must be done as early as
 	 * possible, so that the minimum number of components get
 	 * re-initialized if we jump to another image. */
-	system_pre_init();
 	gpio_pre_init();
 	vboot_pre_init();
 
-	/* TODO (crosbug.com/p/7456)- race condition on enabling
-	 * interrupts.  Module inits should call task_IntEnable(int)
-	 * when they're ready... */
 	task_init();
 
 	watchdog_init(1100);