clockevents: rockchip: Add rockchip timer for rk3288

The rk3288 board uses the architected timers and these ones are shutdown when
the cpu is powered down. There is a need of a broadcast timer in this case to
ensure proper wakeup when the cpus are in sleep mode and a timer expires.

This driver provides the basic timer functionnality as a backup for the local
timers at sleep time.

The timer belongs to the alive subsystem. It includes two programmables 64 bits
timer channels but the driver only uses 32bits. It works with two operations
mode: free running and user defined count.

Programing sequence:

1. Timer initialization:
 * Disable the timer by writing '0' to the CONTROLREG register
 * Program the timer mode by writing the mode to the CONTROLREG register
 * Set the interrupt mask

2. Setting the count value:
 * Load the count value to the registers COUNT0 and COUNT1 (not used).

3. Enable the timer
 * Write '1' to the CONTROLREG register with the mode (free running or user)

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index bfaaae4c21b4..a89120bf640c 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -26,6 +26,10 @@ config DW_APB_TIMER_OF
 	select DW_APB_TIMER
 	select CLKSRC_OF
 
+config ROCKCHIP_TIMER
+	bool
+	select CLKSRC_OF
+
 config ARMADA_370_XP_TIMER
 	bool
 	select CLKSRC_OF