[SCSI] ufs: Add support for host assisted background operations

Background operations in the UFS device can be disabled by
the host to reduce the response latency of transfer requests.
Add support for enabling/disabling the background operations
during runtime suspend/resume of the device.

If the device is in critical need of BKOPS it will raise an
URGENT_BKOPS exception which should be handled by the host to
make sure the device performs as expected.

During bootup, the BKOPS is enabled in the device by default.
The disable of BKOPS is supported only when the driver supports
runtime suspend/resume operations as the runtime PM framework
provides a way to determine the device idleness and hence BKOPS
can be managed effectively. During runtime resume the BKOPS is
disabled to reduce latency and during runtime suspend the BKOPS
is enabled to allow device to carry out idle time BKOPS.

In some cases where the BKOPS is disabled during runtime resume
and due to continuous data transfers the runtime suspend is not
triggered, the BKOPS is enabled when the device raises a level-2
exception (outstanding operations - performance impact).
Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>
Signed-off-by: Santosh Y <santoshsy@gmail.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/ufs/ufs.h

@@ -107,6 +107,28 @@ enum {
 /* Flag idn for Query Requests*/
 enum flag_idn {
 	QUERY_FLAG_IDN_FDEVICEINIT      = 0x01,
+	QUERY_FLAG_IDN_BKOPS_EN         = 0x04,
+};
+
+/* Attribute idn for Query requests */
+enum attr_idn {
+	QUERY_ATTR_IDN_BKOPS_STATUS	= 0x05,
+	QUERY_ATTR_IDN_EE_CONTROL	= 0x0D,
+	QUERY_ATTR_IDN_EE_STATUS	= 0x0E,
+};
+
+/* Exception event mask values */
+enum {
+	MASK_EE_STATUS		= 0xFFFF,
+	MASK_EE_URGENT_BKOPS	= (1 << 2),
+};
+
+/* Background operation status */
+enum {
+	BKOPS_STATUS_NO_OP               = 0x0,
+	BKOPS_STATUS_NON_CRITICAL        = 0x1,
+	BKOPS_STATUS_PERF_IMPACT         = 0x2,
+	BKOPS_STATUS_CRITICAL            = 0x3,
 };
 
 /* UTP QUERY Transaction Specific Fields OpCode */
@@ -155,6 +177,7 @@ enum {
 	MASK_TASK_RESPONSE              = 0xFF00,
 	MASK_RSP_UPIU_RESULT            = 0xFFFF,
 	MASK_QUERY_DATA_SEG_LEN         = 0xFFFF,
+	MASK_RSP_EXCEPTION_EVENT        = 0x10000,
 };
 
 /* Task management service response */

drivers/scsi/ufs/ufshcd.h

@@ -178,9 +178,12 @@ struct ufs_dev_cmd {
  * @tm_condition: condition variable for task management
  * @ufshcd_state: UFSHCD states
  * @intr_mask: Interrupt Mask Bits
+ * @ee_ctrl_mask: Exception event control mask
  * @feh_workq: Work queue for fatal controller error handling
+ * @eeh_work: Worker to handle exception events
  * @errors: HBA errors
  * @dev_cmd: ufs device management command information
+ * @auto_bkops_enabled: to track whether bkops is enabled in device
  */
 struct ufs_hba {
 	void __iomem *mmio_base;
@@ -218,15 +221,19 @@ struct ufs_hba {
 
 	u32 ufshcd_state;
 	u32 intr_mask;
+	u16 ee_ctrl_mask;
 
 	/* Work Queues */
 	struct work_struct feh_workq;
+	struct work_struct eeh_work;
 
 	/* HBA Errors */
 	u32 errors;
 
 	/* Device management request data */
 	struct ufs_dev_cmd dev_cmd;
+
+	bool auto_bkops_enabled;
 };
 
 #define ufshcd_writel(hba, val, reg)	\
@@ -253,4 +260,7 @@ static inline void check_upiu_size(void)
 		GENERAL_UPIU_REQUEST_SIZE + QUERY_DESC_MAX_SIZE);
 }
 
+extern int ufshcd_runtime_suspend(struct ufs_hba *hba);
+extern int ufshcd_runtime_resume(struct ufs_hba *hba);
+extern int ufshcd_runtime_idle(struct ufs_hba *hba);
 #endif /* End of Header */