Add quirk for broken ncq. Some chipsets (eg. BCM7349A0, BCM7445A0,
BCM7445B0, and all 40nm chipsets including BCM7425) need a workaround
disabling NCQ.

Signed-off-by: Jaedon Shin <redacted>
---
 drivers/ata/ahci_brcmstb.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/drivers/ata/ahci_brcmstb.c b/drivers/ata/ahci_brcmstb.c
index 73e3b0b2a3c2..194aeda8f14d 100644
--- a/drivers/ata/ahci_brcmstb.c
+++ b/drivers/ata/ahci_brcmstb.c

@@ -69,10 +69,15 @@
 	(DATA_ENDIAN << DMADESC_ENDIAN_SHIFT) |		\
 	(MMIO_ENDIAN << MMIO_ENDIAN_SHIFT))
 
+enum brcm_ahci_quirks {
+	BRCM_AHCI_QUIRK_NONCQ		= BIT(0),
+};
+
 struct brcm_ahci_priv {
 	struct device *dev;
 	void __iomem *top_ctrl;
 	u32 port_mask;
+	u32 quirks;
 };
 
 static const struct ata_port_info ahci_brcm_port_info = {

@@ -202,6 +207,42 @@ static u32 brcm_ahci_get_portmask(struct platform_device *pdev,
 	return impl;
 }
 
+static void brcm_sata_quirks(struct platform_device *pdev,
+			     struct brcm_ahci_priv *priv)
+{
+	if (priv->quirks & BRCM_AHCI_QUIRK_NONCQ) {
+		void __iomem *ctrl = priv->top_ctrl + SATA_TOP_CTRL_BUS_CTRL;
+		void __iomem *ahci;
+		struct resource *res;
+		u32 reg;
+
+		res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
+						   "ahci");
+		ahci = devm_ioremap_resource(&pdev->dev, res);
+		if (IS_ERR(ahci))
+			return;
+
+		reg = brcm_sata_readreg(ctrl);
+		reg |= OVERRIDE_HWINIT;
+		brcm_sata_writereg(reg, ctrl);
+
+		/* Clear out the NCQ bit so the AHCI driver will not issue
+		 * FPDMA/NCQ commands.
+		 */
+		reg = readl(ahci + HOST_CAP);
+		reg &= ~HOST_CAP_NCQ;
+		writel(reg, ahci + HOST_CAP);

+
+		reg = brcm_sata_readreg(ctrl);
+		reg &= ~OVERRIDE_HWINIT;
+		brcm_sata_writereg(reg, ctrl);
+
+		devm_iounmap(&pdev->dev, ahci);
+		devm_release_mem_region(&pdev->dev, res->start,
+					resource_size(res));
+	}
+}
+
 static void brcm_sata_init(struct brcm_ahci_priv *priv)
 {
 	/* Configure endianness */

@@ -256,6 +297,11 @@ static int brcm_ahci_probe(struct platform_device *pdev)
 	if (IS_ERR(priv->top_ctrl))
 		return PTR_ERR(priv->top_ctrl);
 
+	if (of_device_is_compatible(dev->of_node, "brcm,bcm7425-ahci"))
+		priv->quirks |= BRCM_AHCI_QUIRK_NONCQ;
+
+	brcm_sata_quirks(pdev, priv);
+
 	brcm_sata_init(priv);