FSP/RTC: Fix possible FSP R/R issue in rtc write path
FSP/RTC: Fix possible FSP R/R issue in rtc write path

fsp_opal_rtc_write() checks FSP status before queueing message to FSP. But if
FSP R/R starts before getting response to queued message then we will continue
to return OPAL_BUSY_EVENT to host. In some extreme condition host may
experience hang. Once FSP is back we will repost message, get response from FSP
and return OPAL_SUCCES to host.

This patch caches new values and returns OPAL_SUCCESS if FSP R/R is happening.
And once FSP is back we will send cached value to FSP.

Signed-off-by: Vasant Hegde <a6d753843573f7bfed5075c1e875b0be8007a0ab@linux.vnet.ibm.com>
Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.vnet.ibm.com>

legoater/skiboot,legoater/skiboot,shenki/skiboot,legoater/skiboot,qemu/skiboot,qemu/skiboot,open-power/skiboot,mikey/skiboot,stewart-ibm/skiboot,stewart-ibm/skiboot,open-power/skiboot,shenki/skiboot,open-power/skiboot,legoater/skiboot,mikey/skiboot,stewart-ibm/skiboot,qemu/skiboot,open-power/skiboot,qemu/skiboot,qemu/skiboot,shenki/skiboot,legoater/skiboot,open-power/skiboot,mikey/skiboot,shenki/skiboot,shenki/skiboot