[PATCH AUTOSEL 5.6 129/129] platform/chrome: cros_ec: Query EC protocol version if EC transitions between RO/RW

Sasha Levin
2020-04-15T11:44:54Z

From: Yicheng Li <yichengli@chromium.org>

[ Upstream commit 42cd0ab476e2daffc23982c37822a78f9a53cdd5 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/platform/chrome/cros_ec.c | 30 +++++++++++++++++++++
include/linux/platform_data/cros_ec_proto.h | 4 +++
2 files changed, 34 insertions(+)

diff --git a/drivers/platform/chrome/cros_ec.c b/drivers/platform/chrome/cros_ec.c
index 6fc8f2c3ac517..7ee43b2e0654a 100644
--- a/drivers/platform/chrome/cros_ec.c
+++ b/drivers/platform/chrome/cros_ec.c
@@ -138,6 +138,24 @@ static int cros_ec_sleep_event(struct cros_ec_device *ec_dev, u8 sleep_event)
return ret;
}

+static int cros_ec_ready_event(struct notifier_block *nb,
+ unsigned long queued_during_suspend,
+ void *_notify)
+{
+ struct cros_ec_device *ec_dev = container_of(nb, struct cros_ec_device,
+ notifier_ready);
+ u32 host_event = cros_ec_get_host_event(ec_dev);
+
+ if (host_event & EC_HOST_EVENT_MASK(EC_HOST_EVENT_INTERFACE_READY)) {
+ mutex_lock(&ec_dev->lock);
+ cros_ec_query_all(ec_dev);
+ mutex_unlock(&ec_dev->lock);
+ return NOTIFY_OK;
+ }
+
+ return NOTIFY_DONE;
+}
+
/**
* cros_ec_register() - Register a new ChromeOS EC, using the provided info.
* @ec_dev: Device to register.
@@ -237,6 +255,18 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
dev_dbg(ec_dev->dev, "Error %d clearing sleep event to ec",
err);

+ if (ec_dev->mkbp_event_supported) {
+ /*
+ * Register the notifier for EC_HOST_EVENT_INTERFACE_READY
+ * event.
+ */
+ ec_dev->notifier_ready.notifier_call = cros_ec_ready_event;
+ err = blocking_notifier_chain_register(&ec_dev->event_notifier,
+ &ec_dev->notifier_ready);
+ if (err)
+ return err;
+ }
+
dev_info(dev, "Chrome EC device registered\n");

return 0;
diff --git a/include/linux/platform_data/cros_ec_proto.h b/include/linux/platform_data/cros_ec_proto.h
index ba59147701918..3832433266762 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;
--
2.20.1