drm/bridge: aux-hpd: separate allocation and registration

Combining allocation and registration is an anti-pattern that should be
avoided. Add two new functions for allocating and registering an dp-hpd
bridge with a proper 'devm' prefix so that it is clear that these are
device managed interfaces.

devm_drm_dp_hpd_bridge_alloc()
devm_drm_dp_hpd_bridge_add()

The new interface will be used to fix a use-after-free bug in the
Qualcomm PMIC GLINK driver and may prevent similar issues from being
introduced elsewhere.

The existing drm_dp_hpd_bridge_register() is reimplemented using the
above and left in place for now.

Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Bjorn Andersson <andersson@kernel.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240217150228.5788-3-johan+linaro@kernel.org

drm/bridge: aux-hpd: fix OF node leaks

The two device node references taken during allocation need to be
dropped when the auxiliary device is freed.

Fixes: 6914968a0b52 ("drm/bridge: properly refcount DT nodes in aux bridge drivers")
Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20240217150228.5788-2-johan+linaro@kernel.org
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240217150228.5788-2-johan+linaro@kernel.org

drm/bridge: properly refcount DT nodes in aux bridge drivers

The aux-bridge and aux-hpd-bridge drivers didn't call of_node_get() on
the device nodes further used for dev->of_node and platform data. When
bridge devices are released, the reference counts are decreased,
resulting in refcount underflow / use-after-free warnings. Get
corresponding refcounts during AUX bridge allocation.

Reported-by: Luca Weiss <luca.weiss@fairphone.com>
Fixes: 2a04739139b2 ("drm/bridge: add transparent bridge helper")
Fixes: 26f4bac3d884 ("drm/bridge: aux-hpd: Replace of_device.h with explicit include")
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231216235910.911958-1-dmitry.baryshkov@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

drm/bridge: aux-hpd: Replace of_device.h with explicit include

The DT of_device.h and of_platform.h date back to the separate
of_platform_bus_type before it was merged into the regular platform bus.
As part of that merge prepping Arm DT support 13 years ago, they
"temporarily" include each other. They also include platform_device.h
and of.h. Soon the implicit includes are going to be removed.

of_device.h isn't needed, but of.h is for of_node_put().

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20231207162501.2629952-1-robh@kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>

drm/bridge: implement generic DP HPD bridge

Several USB-C controllers implement a pretty simple DRM bridge which
implements just the HPD notification operations. Add special helper
for creating such simple bridges.

Acked-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231203114333.1305826-5-dmitry.baryshkov@linaro.org