linux-kernel - [char-misc-next 2/6] mei: allow clients on bus to communicate in remove callback

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Date:   Sat,  6 Feb 2021 16:43:21 +0200
From:   Tomas Winkler <tomas.winkler@...el.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Alexander Usyskin <alexander.usyskin@...el.com>,
        linux-kernel@...r.kernel.org,
        Tomas Winkler <tomas.winkler@...el.com>
Subject: [char-misc-next 2/6] mei: allow clients on bus to communicate in remove callback

From: Alexander Usyskin <alexander.usyskin@...el.com>

Introduce new intermediate state to allow the clients on the bus
to communicate with the firmware from the remove handler.
This is to enable to perform a clean shutdown.

Signed-off-by: Alexander Usyskin <alexander.usyskin@...el.com>
Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
---
 drivers/misc/mei/bus.c     | 6 ++++--
 drivers/misc/mei/client.c  | 3 ++-
 drivers/misc/mei/init.c    | 5 ++++-
 drivers/misc/mei/mei_dev.h | 1 +
 4 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/misc/mei/bus.c b/drivers/misc/mei/bus.c
index 2907db260fba..34fb5e541fe5 100644
--- a/drivers/misc/mei/bus.c
+++ b/drivers/misc/mei/bus.c
@@ -44,7 +44,8 @@ ssize_t __mei_cl_send(struct mei_cl *cl, u8 *buf, size_t length, u8 vtag,
 	bus = cl->dev;
 
 	mutex_lock(&bus->device_lock);
-	if (bus->dev_state != MEI_DEV_ENABLED) {
+	if (bus->dev_state != MEI_DEV_ENABLED &&
+	    bus->dev_state != MEI_DEV_POWERING_DOWN) {
 		rets = -ENODEV;
 		goto out;
 	}
@@ -128,7 +129,8 @@ ssize_t __mei_cl_recv(struct mei_cl *cl, u8 *buf, size_t length, u8 *vtag,
 	bus = cl->dev;
 
 	mutex_lock(&bus->device_lock);
-	if (bus->dev_state != MEI_DEV_ENABLED) {
+	if (bus->dev_state != MEI_DEV_ENABLED &&
+	    bus->dev_state != MEI_DEV_POWERING_DOWN) {
 		rets = -ENODEV;
 		goto out;
 	}
diff --git a/drivers/misc/mei/client.c b/drivers/misc/mei/client.c
index beb6cdff20fb..d3f060dce4a6 100644
--- a/drivers/misc/mei/client.c
+++ b/drivers/misc/mei/client.c
@@ -990,7 +990,8 @@ int mei_cl_disconnect(struct mei_cl *cl)
 		return 0;
 	}
 
-	if (dev->dev_state == MEI_DEV_POWER_DOWN) {
+	if (dev->dev_state == MEI_DEV_POWERING_DOWN ||
+	    dev->dev_state == MEI_DEV_POWER_DOWN) {
 		cl_dbg(dev, cl, "Device is powering down, don't bother with disconnection\n");
 		mei_cl_set_disconnected(cl);
 		return 0;
diff --git a/drivers/misc/mei/init.c b/drivers/misc/mei/init.c
index bcee77768b91..5c8cb679b997 100644
--- a/drivers/misc/mei/init.c
+++ b/drivers/misc/mei/init.c
@@ -303,9 +303,12 @@ void mei_stop(struct mei_device *dev)
 	dev_dbg(dev->dev, "stopping the device.\n");
 
 	mutex_lock(&dev->device_lock);
-	mei_set_devstate(dev, MEI_DEV_POWER_DOWN);
+	mei_set_devstate(dev, MEI_DEV_POWERING_DOWN);
 	mutex_unlock(&dev->device_lock);
 	mei_cl_bus_remove_devices(dev);
+	mutex_lock(&dev->device_lock);
+	mei_set_devstate(dev, MEI_DEV_POWER_DOWN);
+	mutex_unlock(&dev->device_lock);
 
 	mei_cancel_work(dev);
 
diff --git a/drivers/misc/mei/mei_dev.h b/drivers/misc/mei/mei_dev.h
index 8c395bfdf6f3..585a6f615bf8 100644
--- a/drivers/misc/mei/mei_dev.h
+++ b/drivers/misc/mei/mei_dev.h
@@ -57,6 +57,7 @@ enum mei_dev_state {
 	MEI_DEV_ENABLED,
 	MEI_DEV_RESETTING,
 	MEI_DEV_DISABLED,
+	MEI_DEV_POWERING_DOWN,
 	MEI_DEV_POWER_DOWN,
 	MEI_DEV_POWER_UP
 };
-- 
2.26.2