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>

diff --git a/drivers/platform/chrome/cros_ec.c b/drivers/platform/chrome/cros_ec.c
index 6fc8f2c..7ee43b2 100644 (file)
--- 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 ba59147..3832433 100644 (file)
--- 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;