Move inline assembly related to querying and counter value as well as
getting and setting counter frequency register into asm/system.h as
well as converting it inot helper functions. This is done to make the
code availible to other parts of the system.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Signed-off-by: Raphael Poggi <poggi.raph@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Add two functions to get/set VBAR register.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

On some SoCs (for example AM35xx), the ROM bootloader passes useful
information in r0 when jumping to barebox.

To avoid overwriting this in the generic reset code, we introduce
common_reset as a C function and as an assembler macro. This is then
called form the reset entry point (either in common or in board code).

This patch is based on code by Sascha Hauer <s.hauer@pengutronix.de>.

Signed-off-by: Jan Luebbe <jlu@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Without it, the compiler optimizes away subsequent reads of the
control register.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>