net: aquantia: Fix hardware reset when SPI may rarely hangup

Under some circumstances (notably using thunderbolt interface) SPI
on chip reset may be in active transaction.
Here we forcibly cleanup SPI to prevent possible hangups.
Signed-off-by: Igor Russkikh <igor.russkikh@aquantia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/aquantia/atlantic/hw_atl/hw_atl_utils.c

@@ -79,16 +79,15 @@ int hw_atl_utils_initfw(struct aq_hw_s *self, const struct aq_fw_ops **fw_ops)
 
 static int hw_atl_utils_soft_reset_flb(struct aq_hw_s *self)
 {
+	u32 gsr, val;
 	int k = 0;
-	u32 gsr;
 
 	aq_hw_write_reg(self, 0x404, 0x40e1);
 	AQ_HW_SLEEP(50);
 
 	/* Cleanup SPI */
-	aq_hw_write_reg(self, 0x534, 0xA0);
-	aq_hw_write_reg(self, 0x100, 0x9F);
-	aq_hw_write_reg(self, 0x100, 0x809F);
+	val = aq_hw_read_reg(self, 0x53C);
+	aq_hw_write_reg(self, 0x53C, val | 0x10);
 
 	gsr = aq_hw_read_reg(self, HW_ATL_GLB_SOFT_RES_ADR);
 	aq_hw_write_reg(self, HW_ATL_GLB_SOFT_RES_ADR, (gsr & 0xBFFF) | 0x8000);
@@ -97,7 +96,14 @@ static int hw_atl_utils_soft_reset_flb(struct aq_hw_s *self)
 	aq_hw_write_reg(self, 0x404, 0x80e0);
 	aq_hw_write_reg(self, 0x32a8, 0x0);
 	aq_hw_write_reg(self, 0x520, 0x1);
+
+	/* Reset SPI again because of possible interrupted SPI burst */
+	val = aq_hw_read_reg(self, 0x53C);
+	aq_hw_write_reg(self, 0x53C, val | 0x10);
 	AQ_HW_SLEEP(10);
+	/* Clear SPI reset state */
+	aq_hw_write_reg(self, 0x53C, val & ~0x10);
+
 	aq_hw_write_reg(self, 0x404, 0x180e0);
 
 	for (k = 0; k < 1000; k++) {
@@ -147,7 +153,7 @@ static int hw_atl_utils_soft_reset_flb(struct aq_hw_s *self)
 
 static int hw_atl_utils_soft_reset_rbl(struct aq_hw_s *self)
 {
-	u32 gsr, rbl_status;
+	u32 gsr, val, rbl_status;
 	int k;
 
 	aq_hw_write_reg(self, 0x404, 0x40e1);
@@ -157,6 +163,10 @@ static int hw_atl_utils_soft_reset_rbl(struct aq_hw_s *self)
 	/* Alter RBL status */
 	aq_hw_write_reg(self, 0x388, 0xDEAD);
 
+	/* Cleanup SPI */
+	val = aq_hw_read_reg(self, 0x53C);
+	aq_hw_write_reg(self, 0x53C, val | 0x10);
+
 	/* Global software reset*/
 	hw_atl_rx_rx_reg_res_dis_set(self, 0U);
 	hw_atl_tx_tx_reg_res_dis_set(self, 0U);