[PATCH v4 8/8] PCI: dwc: Introduce region limit from DT

[Elad Nachman <enachman@marvell.com>]

From: Elad Nachman <enachman@marvell.com>

Allow dts override of region limit for SOCs with older Synopsis
Designware PCIe IP but with greater than 32-bit address range support,
such as the Armada 7020/7040/8040 family of SOCs by Marvell,
when the DT file places the PCIe window above the 4GB region.
The Synopsis Designware PCIe IP in these SOCs is too old to specify the
highest memory location supported by the PCIe, but practically supports
such locations. Allow these locations to be specified in the DT file.
DT property is called num-regionmask , and can range between 33 and 64.

Signed-off-by: Elad Nachman <enachman@marvell.com>
---
v4:
   1) Fix blank lines removal / addition

   2) Remove usage of variable with same name as dt binding property

 drivers/pci/controller/dwc/pcie-designware.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index 53a16b8b6ac2..9773c110c733 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -735,8 +735,10 @@ static void dw_pcie_link_set_max_speed(struct dw_pcie *pci, u32 link_gen)
 void dw_pcie_iatu_detect(struct dw_pcie *pci)
 {
 	int max_region, ob, ib;
-	u32 val, min, dir;
+	u32 val, min, dir, ret;
 	u64 max;
+	struct device *dev = pci->dev;
+	struct device_node *np = dev->of_node;
 
 	val = dw_pcie_readl_dbi(pci, PCIE_ATU_VIEWPORT);
 	if (val == 0xFFFFFFFF) {
@@ -781,7 +783,13 @@ void dw_pcie_iatu_detect(struct dw_pcie *pci)
 		dw_pcie_writel_atu(pci, dir, 0, PCIE_ATU_UPPER_LIMIT, 0xFFFFFFFF);
 		max = dw_pcie_readl_atu(pci, dir, 0, PCIE_ATU_UPPER_LIMIT);
 	} else {
-		max = 0;
+		/* Allow dts override of region limit for older IP with above 32-bit support: */
+		ret = of_property_read_u32(np, "num-regionmask", &val);
+		if (!ret && val > 32) {
+			max = GENMASK(val - 33, 0);
+			dev_info(pci->dev, "Overriding region limit to %u bits\n", val);
+		} else
+			max = 0;
 	}
 
 	pci->num_ob_windows = ob;
-- 
2.17.1