dmaengine: sh: rz-dmac: Add runtime PM support

Protect the driver exposed APIs with runtime PM suspend/resume calls
before accessing HW registers. As the current driver leaves runtime PM
enabled in probe, the purpose of the changes in this patch is to avoid
accessing HW registers after a failed system suspend leaves the runtime
PM state of the device improperly reinitialized.

In that case, the driver remains bound to the device, the APIs are still
exposed, and any access to HW registers without runtime resuming the
device may lead to synchronous aborts.

To avoid leaking resources in case of runtime PM failures, save the error
code returned by PM_RUNTIME_ACQUIRE_ERR() in rz_dmac_terminate_all() and
return it only at the end of the function to allow the cleanup code to
run. A similar approach is used in rz_dmac_free_chan_resources().

Because some exposed APIs (e.g. ->device_terminate_all()) may be called
from atomic context according to the documentation, mark the DMA device as
pm_runtime_irq_safe().

This patch prepares the driver for suspend-to-RAM support.

Tested-by: John Madieu <john.madieu.xa@bp.renesas.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Tested-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
Link: https://patch.msgid.link/20260526084710.3491480-15-claudiu.beznea@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>

0 files changed, 0 insertions, 0 deletions