scsi: mpt3sas: Add separate function for aero doorbell reads

Sometimes Aero controllers appears to be returning bad data (0) for
doorbell register read and if retries are performed immediately after the
bad read, they return good data.

Workaround is added to retry read from doorbell registers for maximum three
times if driver get the zero.  Added functions base_readl_aero for Aero IOC
and base_readl for gen35 and other controllers.

Signed-off-by: Suganath Prabu <suganath-prabu.subramani@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 30 insertions, 0 deletions

diff --git a/drivers/scsi/mpt3sas/mpt3sas_base.c b/drivers/scsi/mpt3sas/mpt3sas_base.c
index 9254b527faa1..d371c8e344d5 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_base.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_base.c
@@ -157,6 +157,32 @@ module_param_call(mpt3sas_fwfault_debug, _scsih_set_fwfault_debug,
 	param_get_int, &mpt3sas_fwfault_debug, 0644);
 
 /**
+ * _base_readl_aero - retry readl for max three times.
+ * @addr - MPT Fusion system interface register address
+ *
+ * Retry the readl() for max three times if it gets zero value
+ * while reading the system interface register.
+ */
+static inline u32
+_base_readl_aero(const volatile void __iomem *addr)
+{
+	u32 i = 0, ret_val;
+
+	do {
+		ret_val = readl(addr);
+		i++;
+	} while (ret_val == 0 && i < 3);
+
+	return ret_val;
+}
+
+static inline u32
+_base_readl(const volatile void __iomem *addr)
+{
+	return readl(addr);
+}
+
+/**
  * _base_clone_reply_to_sys_mem - copies reply to reply free iomem
  *				  in BAR0 space.
  *
@@ -6398,6 +6424,10 @@ mpt3sas_base_attach(struct MPT3SAS_ADAPTER *ioc)
 
 	ioc->rdpq_array_enable_assigned = 0;
 	ioc->dma_mask = 0;
+	if (ioc->is_aero_ioc)
+		ioc->base_readl = &_base_readl_aero;
+	else
+		ioc->base_readl = &_base_readl;
 	r = mpt3sas_base_map_resources(ioc);
 	if (r)
 		goto out_free_resources;