If the CMSDK APB timer is set up with a zero RELOAD value
then it will count down to zero, fire once and then stay
at zero. From the point of view of the ptimer system, the
timer is disabled; but the enable bit in the CTRL register
is still set and if the guest subsequently writes to the
RELOAD or VALUE registers this should cause the timer to
start counting down again.
Add code to the write paths for RELOAD and VALUE so that
we correctly restart the timer in this situation.
Conversely, if the new RELOAD and VALUE are both zero,
we should stop the ptimer.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Message-id: 20180703171044.9503-5-peter.maydell@linaro.org
The CMSDK APB timer is currently always configured as periodic timer.
This results in the following messages when trying to boot Linux.
Timer with delta zero, disabling
If the timer limit set with the RELOAD command is 0, the timer
needs to be enabled as one-shot timer.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
The CMSDK timer interrupt triggers when the counter goes from 1 to 0,
so we want to trigger immediately, rather than waiting for a
clock cycle. Drop the incorrect NO_IMMEDIATE_TRIGGER setting.
We also do not want to get an interrupt if the guest sets the
counter directly to zero, so use the new TRIGGER_ONLY_ON_DECREMENT
policy.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Message-id: 20180703171044.9503-3-peter.maydell@linaro.org
Implement a model of the simple timer device found in the CMSDK.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 1500029487-14822-5-git-send-email-peter.maydell@linaro.org
