platform/chrome: cros_ec: Query EC protocol version if EC transitions between RO/RW

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>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/platform_data/cros_ec_proto.h b/include/linux/platform_data/cros_ec_proto.h
index ba5914770191..383243326676 100644
--- a/include/linux/platform_data/cros_ec_proto.h
+++ b/include/linux/platform_data/cros_ec_proto.h
@@ -125,6 +125,9 @@ struct cros_ec_command {
  * @host_event_wake_mask: Mask of host events that cause wake from suspend.
  * @last_event_time: exact time from the hard irq when we got notified of
  *     a new event.
+ * @notifier_ready: The notifier_block to let the kernel re-query EC
+ *		    communication protocol when the EC sends
+ *		    EC_HOST_EVENT_INTERFACE_READY.
  * @ec: The platform_device used by the mfd driver to interface with the
  *      main EC.
  * @pd: The platform_device used by the mfd driver to interface with the
@@ -166,6 +169,7 @@ struct cros_ec_device {
 	u32 host_event_wake_mask;
 	u32 last_resume_result;
 	ktime_t last_event_time;
+	struct notifier_block notifier_ready;
 
 	/* The platform devices used by the mfd driver */
 	struct platform_device *ec;