[PATCH u-boot v2 4/6] aspeed: Add function to calculate APB Clock frequency

[Maxim Sloyko <maxims@google.com>]

This is needed by I2C driver.

Signed-off-by: Maxim Sloyko <maxims@google.com>
---
Changes for v1:
	Add function comment.
---
 arch/arm/include/asm/arch-aspeed/ast_scu.h |  4 ++++
 arch/arm/mach-aspeed/ast-scu.c             | 13 +++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/arch/arm/include/asm/arch-aspeed/ast_scu.h b/arch/arm/include/asm/arch-aspeed/ast_scu.h
index d248416..6f00e37 100644
--- a/arch/arm/include/asm/arch-aspeed/ast_scu.h
+++ b/arch/arm/include/asm/arch-aspeed/ast_scu.h
@@ -38,6 +38,10 @@ extern void ast_scu_get_who_init_dram(void);
 extern u32 ast_get_clk_source(void);
 extern u32 ast_get_h_pll_clk(void);
 extern u32 ast_get_ahbclk(void);
+/*
+ * Return the frequency of APB clock
+ */
+extern u32 ast_get_apbclk(void);

 extern u32 ast_scu_get_vga_memsize(void);

diff --git a/arch/arm/mach-aspeed/ast-scu.c b/arch/arm/mach-aspeed/ast-scu.c
index 280c421..87236e2 100644
--- a/arch/arm/mach-aspeed/ast-scu.c
+++ b/arch/arm/mach-aspeed/ast-scu.c
@@ -318,6 +318,19 @@ u32 ast_get_ahbclk(void)

 #endif /* AST_SOC_G5 */

+u32 ast_get_apbclk(void)
+{
+	ulong h_pll = ast_get_h_pll_clk();
+
+	/*
+	 * The formula for converting the bit pattern to divisor is
+	 * (4 + 4 * DIV), according to datasheet
+	 */
+	ulong apb_div = 4 + 4 * SCU_GET_PCLK_DIV(ast_scu_read(AST_SCU_CLK_SEL));
+	return h_pll / apb_div;
+}
+
+
 void ast_scu_show_system_info(void)
 {

--
2.8.0.rc3.226.g39d4020