stm32: add support for STM32F0xx family

Add support for the STM32F0xx family of devices using a Cortex-M0 core
and slightly newer peripherals than F1xx family.

Signed-off-by: Vincent Palatin <vpalatin@chromium.org>

BRANCH=none
BUG=none
TEST=run EC console on STM32F072B Discovery board.
and pass all available unit-tests on target.

Change-Id: Idaa3fcbf1c0da8a8f448c0e88e58bfd976b0a735
Reviewed-on: https://chromium-review.googlesource.com/188983
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
Commit-Queue: Vincent Palatin <vpalatin@chromium.org>
Tested-by: Vincent Palatin <vpalatin@chromium.org>

1 files changed, 61 insertions, 0 deletions

diff --git a/chip/stm32/clock-stm32f0.c b/chip/stm32/clock-stm32f0.c
new file mode 100644
index 0000000000..df09e5b67b
--- /dev/null
+++ b/chip/stm32/clock-stm32f0.c
@@ -0,0 +1,61 @@
+/* Copyright (c) 2014 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.
+ */
+
+/* Clocks and power management settings */
+
+#include "chipset.h"
+#include "clock.h"
+#include "common.h"
+#include "console.h"
+#include "cpu.h"
+#include "hooks.h"
+#include "registers.h"
+#include "util.h"
+
+/* use 48Mhz USB-synchronized High-speed oscillator */
+#define HSI48_CLOCK 48000000
+
+int clock_get_freq(void)
+{
+	return HSI48_CLOCK;
+}
+
+void clock_enable_module(enum module_id module, int enable)
+{
+}
+
+/*
+ * system closk is HSI48 = 48MHz,
+ * no prescaler, no MCO, no PLL
+ * USB clock = HSI48
+ */
+BUILD_ASSERT(CPU_CLOCK == HSI48_CLOCK);
+
+void clock_init(void)
+{
+	/*
+	 * The initial state :
+	 *  SYSCLK from HSI (=8MHz), no divider on AHB, APB1, APB2
+	 *  PLL unlocked, RTC enabled on LSE
+	 */
+
+	/* put 1 Wait-State for flash access to ensure proper reads at 48Mhz */
+	STM32_FLASH_ACR = 0x1001; /* 1 WS / Prefetch enabled */
+
+	/* Ensure that HSI48 is ON */
+	if (!(STM32_RCC_CR2 & (1 << 17))) {
+		/* Enable HSI */
+		STM32_RCC_CR2 |= 1 << 16;
+		/* Wait for HSI to be ready */
+		while (!(STM32_RCC_CR2 & (1 << 17)))
+			;
+	}
+	/* switch SYSCLK to HSI48 */
+	STM32_RCC_CFGR = 0x00000003;
+
+	/* wait until the HSI48 is the clock source */
+	while ((STM32_RCC_CFGR & 0xc) != 0xc)
+		;
+}