[char-misc-next 7/7] mei: csc: wake device while reading firmware status

[Alexander Usyskin <alexander.usyskin@intel.com>]

The CSC has firmware status registers in MMIO and they may be
unaccessible while device is suspended.
Wake device while reading firmware status via sysfs.

Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
---
 drivers/misc/mei/main.c    | 18 ++++++++++++++----
 drivers/misc/mei/mei_dev.h |  2 ++
 drivers/misc/mei/pci-csc.c |  2 ++
 3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/misc/mei/main.c b/drivers/misc/mei/main.c
index 6f26d5160788..54f70f513482 100644
--- a/drivers/misc/mei/main.c
+++ b/drivers/misc/mei/main.c
@@ -4,6 +4,7 @@
  * Intel Management Engine Interface (Intel MEI) Linux driver
  */
 
+#include <linux/cleanup.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/kernel.h>
@@ -13,6 +14,7 @@
 #include <linux/errno.h>
 #include <linux/types.h>
 #include <linux/fcntl.h>
+#include <linux/pm_runtime.h>
 #include <linux/poll.h>
 #include <linux/init.h>
 #include <linux/ioctl.h>
@@ -982,14 +984,22 @@ static DEVICE_ATTR_RO(trc);
 static ssize_t fw_status_show(struct device *device,
 		struct device_attribute *attr, char *buf)
 {
-	struct mei_device *dev = dev_get_drvdata(device);
+	struct mei_device *mdev = dev_get_drvdata(device);
 	struct mei_fw_status fw_status;
 	int err, i;
 	ssize_t cnt = 0;
 
-	mutex_lock(&dev->device_lock);
-	err = mei_fw_status(dev, &fw_status);
-	mutex_unlock(&dev->device_lock);
+	if (mdev->read_fws_need_resume) {
+		err = pm_runtime_resume_and_get(mdev->parent);
+		if (err) {
+			dev_err(device, "read fw_status resume error = %d\n", err);
+			return err;
+		}
+	}
+	scoped_guard(mutex, &mdev->device_lock)
+		err = mei_fw_status(mdev, &fw_status);
+	if (mdev->read_fws_need_resume)
+		pm_runtime_put_autosuspend(mdev->parent);
 	if (err) {
 		dev_err(device, "read fw_status error = %d\n", err);
 		return err;
diff --git a/drivers/misc/mei/mei_dev.h b/drivers/misc/mei/mei_dev.h
index 1796c6793a94..d8634a726990 100644
--- a/drivers/misc/mei/mei_dev.h
+++ b/drivers/misc/mei/mei_dev.h
@@ -491,6 +491,7 @@ struct mei_dev_timeouts {
  *
  * @recvd_hw_ready : hw ready message received flag
  * @pg_blocked  : low power mode is not allowed
+ * @read_fws_need_resume: the FW status handler needs HW woken from sleep
  *
  * @wait_hw_ready : wait queue for receive HW ready message form FW
  * @wait_pg     : wait queue for receive PG message from FW
@@ -577,6 +578,7 @@ struct mei_device {
 
 	bool recvd_hw_ready;
 	bool pg_blocked;
+	bool read_fws_need_resume;
 
 	/*
 	 * waiting queue for receive message from FW
diff --git a/drivers/misc/mei/pci-csc.c b/drivers/misc/mei/pci-csc.c
index 15e170b1e0b6..70792bf9b3c0 100644
--- a/drivers/misc/mei/pci-csc.c
+++ b/drivers/misc/mei/pci-csc.c
@@ -67,6 +67,8 @@ static int mei_csc_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (!mdev)
 		return -ENOMEM;
 
+	mdev->read_fws_need_resume = true;
+
 	hw = to_me_hw(mdev);
 
 	/*
-- 
2.43.0