mlxsw: pci: Implement reset done check

Firmware now tells us that the reset is done by passing a magic value
via register. Use it to shorten the wait in case this is supported.
With old firmware, we still wait until the timeout is reached.
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/pci.c

@@ -1681,11 +1681,18 @@ static const struct mlxsw_bus mlxsw_pci_bus = {
 
 static int mlxsw_pci_sw_reset(struct mlxsw_pci *mlxsw_pci)
 {
+	unsigned long end;
+
 	mlxsw_pci_write32(mlxsw_pci, SW_RESET, MLXSW_PCI_SW_RESET_RST_BIT);
-	/* Current firware does not let us know when the reset is done.
-	 * So we just wait here for constant time and hope for the best.
-	 */
-	msleep(MLXSW_PCI_SW_RESET_TIMEOUT_MSECS);
+	wmb(); /* reset needs to be written before we read control register */
+	end = jiffies + msecs_to_jiffies(MLXSW_PCI_SW_RESET_TIMEOUT_MSECS);
+	do {
+		u32 val = mlxsw_pci_read32(mlxsw_pci, FW_READY);
+
+		if ((val & MLXSW_PCI_FW_READY_MASK) == MLXSW_PCI_FW_READY_MAGIC)
+			break;
+		cond_resched();
+	} while (time_before(jiffies, end));
 	return 0;
 }
 

drivers/net/ethernet/mellanox/mlxsw/pci.h

@@ -61,6 +61,9 @@
 #define MLXSW_PCI_SW_RESET			0xF0010
 #define MLXSW_PCI_SW_RESET_RST_BIT		BIT(0)
 #define MLXSW_PCI_SW_RESET_TIMEOUT_MSECS	5000
+#define MLXSW_PCI_FW_READY			0xA1844
+#define MLXSW_PCI_FW_READY_MASK			0xFF
+#define MLXSW_PCI_FW_READY_MAGIC		0x5E
 
 #define MLXSW_PCI_DOORBELL_SDQ_OFFSET		0x000
 #define MLXSW_PCI_DOORBELL_RDQ_OFFSET		0x200