[PATCH 4/8] scsi: ufs: Make .get_hba_mac() optional

[Bart Van Assche <bvanassche@acm.org>]

UFSHCI controllers that are compliant with the UFSHCI 4.0 standard report
the maximum number of supported commands in the controller capabilities
register. Use that value if .get_hba_mac == NULL.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/ufs/core/ufs-mcq.c | 12 +++++++-----
 include/ufs/ufshcd.h       |  4 +++-
 include/ufs/ufshci.h       |  2 +-
 3 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/ufs/core/ufs-mcq.c b/drivers/ufs/core/ufs-mcq.c
index 0482c7a1e419..d6f966f4abef 100644
--- a/drivers/ufs/core/ufs-mcq.c
+++ b/drivers/ufs/core/ufs-mcq.c
@@ -138,7 +138,6 @@ EXPORT_SYMBOL_GPL(ufshcd_mcq_queue_cfg_addr);
  *
  * MAC - Max. Active Command of the Host Controller (HC)
  * HC wouldn't send more than this commands to the device.
- * It is mandatory to implement get_hba_mac() to enable MCQ mode.
  * Calculates and adjusts the queue depth based on the depth
  * supported by the HC and ufs device.
  */
@@ -146,10 +145,13 @@ int ufshcd_mcq_decide_queue_depth(struct ufs_hba *hba)
 {
 	int mac = -EOPNOTSUPP;
 
-	if (!hba->vops || !hba->vops->get_hba_mac)
-		goto err;
-
-	mac = hba->vops->get_hba_mac(hba);
+	if (!hba->vops || !hba->vops->get_hba_mac) {
+		hba->capabilities =
+			ufshcd_readl(hba, REG_CONTROLLER_CAPABILITIES);
+		mac = (hba->capabilities & MASK_TRANSFER_REQUESTS_SLOTS) + 1;
+	} else {
+		mac = hba->vops->get_hba_mac(hba);
+	}
 	if (mac < 0)
 		goto err;
 
diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
index d4d63507d090..d32637d267f3 100644
--- a/include/ufs/ufshcd.h
+++ b/include/ufs/ufshcd.h
@@ -325,7 +325,9 @@ struct ufs_pwr_mode_info {
  * @event_notify: called to notify important events
  * @reinit_notify: called to notify reinit of UFSHCD during max gear switch
  * @mcq_config_resource: called to configure MCQ platform resources
- * @get_hba_mac: called to get vendor specific mac value, mandatory for mcq mode
+ * @get_hba_mac: reports maximum number of outstanding commands supported by
+ *	the controller. Should be implemented for UFSHCI 4.0 or later
+ *	controllers that are not compliant with the UFSHCI 4.0 specification.
  * @op_runtime_config: called to config Operation and runtime regs Pointers
  * @get_outstanding_cqs: called to get outstanding completion queues
  * @config_esi: called to config Event Specific Interrupt
diff --git a/include/ufs/ufshci.h b/include/ufs/ufshci.h
index c50f92bf2e1d..899077bba2d2 100644
--- a/include/ufs/ufshci.h
+++ b/include/ufs/ufshci.h
@@ -67,7 +67,7 @@ enum {
 
 /* Controller capability masks */
 enum {
-	MASK_TRANSFER_REQUESTS_SLOTS		= 0x0000001F,
+	MASK_TRANSFER_REQUESTS_SLOTS		= 0x000000FF,
 	MASK_NUMBER_OUTSTANDING_RTT		= 0x0000FF00,
 	MASK_TASK_MANAGEMENT_REQUEST_SLOTS	= 0x00070000,
 	MASK_EHSLUTRD_SUPPORTED			= 0x00400000,