[ Upstream commit 57b888ca2541785de2fcb90575b378921919b6c0 ]

Commit 413dda8f2c6f ("platform/chrome: cros_ec_chardev: Use
cros_ec_cmd_xfer_status helper") inadvertendly changed the userspace ABI.
Previously, cros_ec ioctls would only report errors if the EC communication
failed, and otherwise return success and the result of the EC
communication. An EC command execution failure was reported in the EC
response field. The above mentioned commit changed this behavior, and the
ioctl itself would fail. This breaks userspace commands trying to analyze
the EC command execution error since the actual EC command response is no
longer reported to userspace.

Fix the problem by re-introducing the cros_ec_cmd_xfer() helper, and use it
to handle ioctl messages.

Fixes: 413dda8f2c6f ("platform/chrome: cros_ec_chardev: Use cros_ec_cmd_xfer_status helper")
Cc: Daisuke Nojiri <dnojiri@chromium.org>
Cc: Rob Barnes <robbarnes@google.com>
Cc: Rajat Jain <rajatja@google.com>
Cc: Brian Norris <briannorris@chromium.org>
Cc: Parth Malkan <parthmalkan@google.com>
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

The Chrome EC's features are returned through an
ec_response_get_features struct, but they are stored in an independent
array. Although the two are effectively the same at present (2 unsigned
32 bit ints), there is the possibility that they could go out of sync.
Avoid this by only using the EC struct to store the features.

Signed-off-by: Prashant Malani <pmalani@chromium.org>
Link: https://lore.kernel.org/r/20211004170716.86601-1-pmalani@chromium.org
Signed-off-by: Benson Leung <bleung@chromium.org>

Add a version parameter to cros_ec_command() for callers that may want
to specify which version of the host command they would like to use.

Signed-off-by: Prashant Malani <pmalani@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Link: https://lore.kernel.org/r/20210930022403.3358070-5-pmalani@chromium.org

Convert the input and output data pointers for cros_ec_command() to
void pointers so that the callers don't have to cast their custom
structs to uint8_t *.

Signed-off-by: Prashant Malani <pmalani@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Link: https://lore.kernel.org/r/20210930022403.3358070-4-pmalani@chromium.org

cros_ec_command() can be used by other modules too. So, move it to a
common location and export it.

This patch does not introduce any functional changes.

Signed-off-by: Prashant Malani <pmalani@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Link: https://lore.kernel.org/r/20210930022403.3358070-3-pmalani@chromium.org

The kerneldoc for cros_ec_check_features() states that it returns 1 or 0
depedending on whether a feature is supported or not, but it instead
returns a negative error number in one case, and a non-1 bitmask in
other cases.

Since all call-sites only check for a 1 or 0 return value, update
the function to return boolean values.

Signed-off-by: Prashant Malani <pmalani@chromium.org>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Link: https://lore.kernel.org/r/20210916014632.2662612-1-pmalani@chromium.org

There is a regular need in the kernel to provide a way to declare having a
dynamically sized set of trailing elements in a structure. Kernel code should
always use “flexible array members”[1] for these cases. The older style of
one-element or zero-length arrays should no longer be used[2].

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.9-rc1/process/deprecated.html#zero-length-and-one-element-arrays

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Now that all the remaining users of cros_ec_cmd_xfer() has been removed,
make this function private to the cros_ec_proto module.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

RO and RW of EC may have different EC protocol version. If EC transitions
between RO and RW, but AP does not reboot (this is true for fingerprint
microcontroller / cros_fp, but not true for main ec / cros_ec), the AP
still uses the protocol version queried before transition, which can
cause problems. In the case of fingerprint microcontroller, this causes
AP to send the wrong version of EC_CMD_GET_NEXT_EVENT to RO in the
interrupt handler, which in turn prevents RO to clear the interrupt
line to AP, in an infinite loop.

Once an EC_HOST_EVENT_INTERFACE_READY is received, we know that there
might have been a transition between RO and RW, so re-query the protocol.

Signed-off-by: Yicheng Li <yichengli@chromium.org>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

The 'cros_ec' core driver is the common interface for the cros_ec
transport drivers to do the shared operations to register, unregister,
suspend, resume and handle_event. The interface is provided by including
the header 'include/linux/platform_data/cros_ec_proto.h', however, instead
of have the implementation of these functions in cros_ec_proto.c, it is in
'cros_ec.c', which is a different kernel module. Apart from being a bad
practice, this can induce confusions allowing the users of the cros_ec
protocol to call these functions.

The register, unregister, suspend, resume and handle_event functions
*should* only be called by the different transport drivers (i2c, spi, lpc,
etc.), so make this a bit less confusing by moving these functions from
the public in-kernel space to a private include in platform/chrome, and
then, the interface for cros_ec module and for the cros_ec_proto module is
clean.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Benson Leung <bleung@chromium.org>