ata: ahci-platform: Add ports-implemented DT bindings.

[ Upstream commit 17dcc37e3e847bc0e67a5b1ec52471fcc6c18682 ]

On some SOCs PORTS_IMPL register value is never programmed by the
firmware and left at zero value. Which means that no sata ports are
available for software. AHCI driver used to cope up with this by
fabricating the port_map if the PORTS_IMPL register is read zero,
but recent patch broke this workaround as zero value was valid for
NVMe disks.

This patch adds ports-implemented DT bindings as workaround for this issue
in a way that DT can can override the PORTS_IMPL register in cases where
the firmware did not program it already.

Fixes: 566d1827df2e ("libata: disable forced PORTS_IMPL for >= AHCI 1.3")
Cc: stable@vger.kernel.org # v4.5+
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andy Gross <andy.gross@linaro.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>

diff --git a/Documentation/devicetree/bindings/ata/ahci-platform.txt b/Documentation/devicetree/bindings/ata/ahci-platform.txt
index 4ab09f2202d444c43717502207c23618955a4101..e6d5a4aa953f46cc2a01eaedc04c4bd2852c1db0 100644 (file)
--- a/Documentation/devicetree/bindings/ata/ahci-platform.txt
+++ b/Documentation/devicetree/bindings/ata/ahci-platform.txt
@@ -30,6 +30,10 @@ Optional properties:
 - target-supply     : regulator for SATA target power
 - phys              : reference to the SATA PHY node
 - phy-names         : must be "sata-phy"
+- ports-implemented : Mask that indicates which ports that the HBA supports
+                     are available for software to use. Useful if PORTS_IMPL
+                     is not programmed by the BIOS, which is true with
+                     some embedded SOC's.
 
 Required properties when using sub-nodes:
 - #address-cells    : number of cells to encode an address

diff --git a/drivers/ata/ahci_platform.c b/drivers/ata/ahci_platform.c
index 06f1d59fa678fe8da1da0b90d730025aca689796..83c2b8be99b839dacdf8999209583ad05cfdbfe4 100644 (file)
--- a/drivers/ata/ahci_platform.c
+++ b/drivers/ata/ahci_platform.c
@@ -43,6 +43,9 @@ static int ahci_probe(struct platform_device *pdev)
        if (rc)
                return rc;
 
+       of_property_read_u32(dev->of_node,
+                            "ports-implemented", &hpriv->force_port_map);
+
        if (of_device_is_compatible(dev->of_node, "hisilicon,hisi-ahci"))
                hpriv->flags |= AHCI_HFLAG_NO_FBS | AHCI_HFLAG_NO_NCQ;