ahci_xgene: Skip the PHY and clock initialization if already configured by the firmware.

This patch implements the feature to skip the PHY and clock
initialization if it is already configured by the firmware.

Signed-off-by: Loc Ho <lho@apm.com>
Signed-off-by: Suman Tripathi <stripathi@apm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/drivers/ata/ahci_xgene.c b/drivers/ata/ahci_xgene.c
index c696230..37501fd 100644
--- a/drivers/ata/ahci_xgene.c
+++ b/drivers/ata/ahci_xgene.c
@@ -145,6 +145,14 @@
 	return rc;
 }
 
+static bool xgene_ahci_is_memram_inited(struct xgene_ahci_context *ctx)
+{
+	void __iomem *diagcsr = ctx->csr_diag;
+
+	return (readl(diagcsr + CFG_MEM_RAM_SHUTDOWN) == 0 &&
+	        readl(diagcsr + BLOCK_MEM_RDY) == 0xFFFFFFFF);
+}
+
 /**
  * xgene_ahci_read_id - Read ID data from the specified device
  * @dev: device
@@ -467,6 +475,11 @@
 		return -ENODEV;
 	}
 
+	if (xgene_ahci_is_memram_inited(ctx)) {
+		dev_info(dev, "skip clock and PHY initialization\n");
+		goto skip_clk_phy;
+	}
+
 	/* Due to errata, HW requires full toggle transition */
 	rc = ahci_platform_enable_clks(hpriv);
 	if (rc)
@@ -479,7 +492,7 @@
 
 	/* Configure the host controller */
 	xgene_ahci_hw_init(hpriv);
-
+skip_clk_phy:
 	hpriv->flags = AHCI_HFLAG_NO_PMP | AHCI_HFLAG_NO_NCQ;
 
 	rc = ahci_platform_init_host(pdev, hpriv, &xgene_ahci_port_info);