[RESEND PATCH v3] scsi: ufshcd: fix possible unclocked register access

* [RESEND PATCH v3] scsi: ufshcd: fix possible unclocked register access
@ 2016-10-07  4:48   ` Subhash Jadavani
  0 siblings, 0 replies; 6+ messages in thread
From: Subhash Jadavani @ 2016-10-07  4:48 UTC (permalink / raw)
  To: vinholikatti, jejb, martin.petersen
  Cc: Subhash Jadavani,
	open list:UNIVERSAL FLASH STORAGE HOST CONTROLLER DRIVER,
	open list

Vendor specific setup_clocks callback may require the clocks managed
by ufshcd driver to be ON. So if the vendor specific setup_clocks callback
is called while the required clocks are turned off, it could result into
unclocked register access.

To prevent possible unclock register access, this change adds one more
argument to setup_clocks callback to let it know whether it is called
pre/post the clock changes by core driver.

Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
---
Changes from v2:
* Added one more argument to setup_clocks callback, this should address
  Kiwoong Kim's comments on v2.

Changes from v1:
* Don't call ufshcd_vops_setup_clocks() again for clock off
---
 drivers/scsi/ufs/ufs-qcom.c | 10 ++++++----
 drivers/scsi/ufs/ufshcd.c   | 17 ++++++++---------
 drivers/scsi/ufs/ufshcd.h   |  8 +++++---
 3 files changed, 19 insertions(+), 16 deletions(-)

diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
index 3aedf73..3c4f602 100644
--- a/drivers/scsi/ufs/ufs-qcom.c
+++ b/drivers/scsi/ufs/ufs-qcom.c
@@ -1094,10 +1094,12 @@ static void ufs_qcom_set_caps(struct ufs_hba *hba)
  * ufs_qcom_setup_clocks - enables/disable clocks
  * @hba: host controller instance
  * @on: If true, enable clocks else disable them.
+ * @status: PRE_CHANGE or POST_CHANGE notify
  *
  * Returns 0 on success, non-zero on failure.
  */
-static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on)
+static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
+				 enum ufs_notify_change_status status)
 {
 	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
 	int err;
@@ -1111,7 +1113,7 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on)
 	if (!host)
 		return 0;
 
-	if (on) {
+	if (on && (status == POST_CHANGE)) {
 		err = ufs_qcom_phy_enable_iface_clk(host->generic_phy);
 		if (err)
 			goto out;
@@ -1130,7 +1132,7 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on)
 		if (vote == host->bus_vote.min_bw_vote)
 			ufs_qcom_update_bus_bw_vote(host);
 
-	} else {
+	} else if (!on && (status == PRE_CHANGE)) {
 
 		/* M-PHY RMMI interface clocks can be turned off */
 		ufs_qcom_phy_disable_iface_clk(host->generic_phy);
@@ -1254,7 +1256,7 @@ static int ufs_qcom_init(struct ufs_hba *hba)
 	ufs_qcom_set_caps(hba);
 	ufs_qcom_advertise_quirks(hba);
 
-	ufs_qcom_setup_clocks(hba, true);
+	ufs_qcom_setup_clocks(hba, true, POST_CHANGE);
 
 	if (hba->dev->id < MAX_UFS_QCOM_HOSTS)
 		ufs_qcom_hosts[hba->dev->id] = host;
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 05c7456..571a2f6 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -5389,6 +5389,10 @@ static int __ufshcd_setup_clocks(struct ufs_hba *hba, bool on,
 	if (!head || list_empty(head))
 		goto out;
 
+	ret = ufshcd_vops_setup_clocks(hba, on, PRE_CHANGE);
+	if (ret)
+		return ret;
+
 	list_for_each_entry(clki, head, list) {
 		if (!IS_ERR_OR_NULL(clki->clk)) {
 			if (skip_ref_clk && !strcmp(clki->name, "ref_clk"))
@@ -5410,7 +5414,10 @@ static int __ufshcd_setup_clocks(struct ufs_hba *hba, bool on,
 		}
 	}
 
-	ret = ufshcd_vops_setup_clocks(hba, on);
+	ret = ufshcd_vops_setup_clocks(hba, on, POST_CHANGE);
+	if (ret)
+		return ret;
+
 out:
 	if (ret) {
 		list_for_each_entry(clki, head, list) {
@@ -5500,8 +5507,6 @@ static void ufshcd_variant_hba_exit(struct ufs_hba *hba)
 	if (!hba->vops)
 		return;
 
-	ufshcd_vops_setup_clocks(hba, false);
-
 	ufshcd_vops_setup_regulators(hba, false);
 
 	ufshcd_vops_exit(hba);
@@ -5905,10 +5910,6 @@ disable_clks:
 	if (ret)
 		goto set_link_active;
 
-	ret = ufshcd_vops_setup_clocks(hba, false);
-	if (ret)
-		goto vops_resume;
-
 	if (!ufshcd_is_link_active(hba))
 		ufshcd_setup_clocks(hba, false);
 	else
@@ -5925,8 +5926,6 @@ disable_clks:
 	ufshcd_hba_vreg_set_lpm(hba);
 	goto out;
 
-vops_resume:
-	ufshcd_vops_resume(hba, pm_op);
 set_link_active:
 	ufshcd_vreg_set_hpm(hba);
 	if (ufshcd_is_link_hibern8(hba) && !ufshcd_uic_hibern8_exit(hba))
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index 430bef1..afff7f4 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -273,7 +273,8 @@ struct ufs_hba_variant_ops {
 	u32	(*get_ufs_hci_version)(struct ufs_hba *);
 	int	(*clk_scale_notify)(struct ufs_hba *, bool,
 				    enum ufs_notify_change_status);
-	int	(*setup_clocks)(struct ufs_hba *, bool);
+	int	(*setup_clocks)(struct ufs_hba *, bool,
+				enum ufs_notify_change_status);
 	int     (*setup_regulators)(struct ufs_hba *, bool);
 	int	(*hce_enable_notify)(struct ufs_hba *,
 				     enum ufs_notify_change_status);
@@ -755,10 +756,11 @@ static inline int ufshcd_vops_clk_scale_notify(struct ufs_hba *hba,
 	return 0;
 }
 
-static inline int ufshcd_vops_setup_clocks(struct ufs_hba *hba, bool on)
+static inline int ufshcd_vops_setup_clocks(struct ufs_hba *hba, bool on,
+					enum ufs_notify_change_status status)
 {
 	if (hba->vops && hba->vops->setup_clocks)
-		return hba->vops->setup_clocks(hba, on);
+		return hba->vops->setup_clocks(hba, on, status);
 	return 0;
 }
 
-- 
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