[PATCH] sil24: add sil24_restart_controller

[PATCH] sil24: add sil24_restart_controller

When an error condition is raised by device via D2H FIS or SDB.  sil24
controller should be restarted by setting PORT_CS_INIT and waiting
until PORT_CS_RDY is asserted instead of resetting the controller.
This patch implements sil24_restart_controller for those cases.  This
patch also makes sure that PORT_CS_RDY is asserted on
sil24_reset_controller completion.

Signed-off-by: Tejun Heo <htejun@gmail.com>
--

Jeff, delay is reduced to 1us and cnt increased to 10k.  My sil3124
turns on PORT_CS_RDY on the second iteration even without any delay.
I think 10k * 1us should be more than enough.

I tried to convert both restart and reset to use msleep's with work
queue, but if we do that, host_set lock should be released after
initiating restart or reset, leading to race condition among
reset/restart, other interrupts and timeout.  Implementing
synchronization among those in low-level driver doesn't seem right.
Well, reduced timeout should work for the time being.

Thanks.
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>