[U-Boot] [PATCH v4] Allow AM335x MPU core clock speed to be specified in the board config file

[Mark Jackson <mpfj-list@mimc.co.uk>]

Allow AM335x MPU core clock speed to be specified in the board config file.
To use, add the following to the board's config file:-

#define CONFIG_SYS_MPUCLK	<desired clock freq in MHz>

Signed-off-by: Mark Jackson <mpfj@newflow.co.uk>
---
Changes in v4:
- Now defined as MHz (not Hz)

Changes in v3:
- Changed from V_MPUCLK to CONFIG_SYS_MPUCLK
- Added entry in README

Changes in v2:
- Tweaked after comments from Peter Korsgaard

 README                                           |    4 ++++
 arch/arm/include/asm/arch-am33xx/clocks_am33xx.h |    7 +++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/README b/README
index d8cb394..ddf6df2 100644
--- a/README
+++ b/README
@@ -3820,6 +3820,10 @@ Low Level (hardware related) configuration options:
 		If defined, the x86 reset vector code is included. This is not
 		needed when U-Boot is running from Coreboot.
 
+- CONFIG_SYS_MPUCLK
+		Defines the MPU clock speed (in MHz).
+
+		NOTE : currently only supported on AM335x platforms.
 
 Freescale QE/FMAN Firmware Support:
 -----------------------------------
diff --git a/arch/arm/include/asm/arch-am33xx/clocks_am33xx.h b/arch/arm/include/asm/arch-am33xx/clocks_am33xx.h
index d748dd2..2d96007 100644
--- a/arch/arm/include/asm/arch-am33xx/clocks_am33xx.h
+++ b/arch/arm/include/asm/arch-am33xx/clocks_am33xx.h
@@ -21,8 +21,11 @@
 
 #define OSC	(V_OSCK/1000000)
 
-/* MAIN PLL Fdll = 550 MHZ, */
-#define MPUPLL_M	550
+/* MAIN PLL Fdll = 550 MHz, by default */
+#ifndef CONFIG_SYS_MPUCLK
+#define CONFIG_SYS_MPUCLK	550
+#endif
+#define MPUPLL_M	CONFIG_SYS_MPUCLK
 #define MPUPLL_N	(OSC-1)
 #define MPUPLL_M2	1
 
-- 
1.7.9.5