platform/x86: intel_scu_ipc: Check status after timeout in busy_loop()

platform/x86: intel_scu_ipc: Check status after timeout in busy_loop()

[ Upstream commit e0b4ab3bb92bda8d12f55842614362989d5b2cb3 ]

It's possible for the polling loop in busy_loop() to get scheduled away
for a long time.

  status = ipc_read_status(scu); // status = IPC_STATUS_BUSY
  <long time scheduled away>
  if (!(status & IPC_STATUS_BUSY))

If this happens, then the status bit could change while the task is
scheduled away and this function would never read the status again after
timing out. Instead, the function will return -ETIMEDOUT when it's
possible that scheduling didn't work out and the status bit was cleared.
Bit polling code should always check the bit being polled one more time
after the timeout in case this happens.

Fix this by reading the status once more after the while loop breaks.
The readl_poll_timeout() macro implements all of this, and it is
shorter, so use that macro here to consolidate code and fix this.

There were some concerns with using readl_poll_timeout() because it uses
timekeeping, and timekeeping isn't running early on or during the late
stages of system suspend or early stages of system resume, but an audit
of the code concluded that this code isn't called during those times so
it is safe to use the macro.

Cc: Prashant Malani <pmalani@chromium.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Fixes: e7b7ab3847c9 ("platform/x86: intel_scu_ipc: Sleeping is fine when polling")
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20230913212723.3055315-2-swboyd@chromium.org
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>