platform/chrome: cros_ec_typec: Check for EC device

commit ffebd90532728086007038986900426544e3df4e upstream.

The Type C ACPI device on older Chromebooks is not generated correctly
(since their EC firmware doesn't support the new commands required). In
such cases, the crafted ACPI device doesn't have an EC parent, and it is
therefore not useful (it shouldn't be generated in the first place since
the EC firmware doesn't support any of the Type C commands).

To handle devices which use these older firmware revisions, check for
the parent EC device handle, and fail the probe if it's not found.

Fixes: fdc6b21e2444 ("platform/chrome: Add Type C connector class driver")
Reported-by: Alyssa Ross <hi@alyssa.is>
Reviewed-by: Tzung-Bi Shih <tzungbi@google.com>
Signed-off-by: Prashant Malani <pmalani@chromium.org>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Alyssa Ross <hi@alyssa.is>
Tested-by: Alyssa Ross <hi@alyssa.is>
Link: https://lore.kernel.org/r/20220126190219.3095419-1-pmalani@chromium.org
Signed-off-by: Benson Leung <bleung@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
index 262a891..4027c3e 100644 (file)
--- a/drivers/platform/chrome/cros_ec_typec.c
+++ b/drivers/platform/chrome/cros_ec_typec.c
@@ -1106,7 +1106,13 @@ static int cros_typec_probe(struct platform_device *pdev)
                return -ENOMEM;
 
        typec->dev = dev;
+
        typec->ec = dev_get_drvdata(pdev->dev.parent);
+       if (!typec->ec) {
+               dev_err(dev, "couldn't find parent EC device\n");
+               return -ENODEV;
+       }
+
        platform_set_drvdata(pdev, typec);
 
        ret = cros_typec_get_cmd_version(typec);