[PATCHv4 6/9] PCI: designware: add accessors for write permission of DBI read-only registers

[Zhiqiang Hou <Zhiqiang.Hou@nxp.com>]

From: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>

The read-only DBI registers can be written over the DBI when set
the "Write to RO Registers Using DBI" (DBI_RO_WR_EN) field of the
MISC_CONTROL_1_OFF register.

Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Acked-By: Joao Pinto <jpinto@synopsys.com>
---
V4:
 - no change

 drivers/pci/dwc/pcie-designware.h | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/pci/dwc/pcie-designware.h b/drivers/pci/dwc/pcie-designware.h
index 7366c8167404..0c5f874345f6 100644
--- a/drivers/pci/dwc/pcie-designware.h
+++ b/drivers/pci/dwc/pcie-designware.h
@@ -76,6 +76,9 @@
 #define PCIE_ATU_FUNC(x)		(((x) & 0x7) << 16)
 #define PCIE_ATU_UPPER_TARGET		0x91C
 
+#define PCIE_MISC_CONTROL_1_OFF		0x8BC
+#define PCIE_DBI_RO_WR_EN		(0x1 << 0)
+
 /*
  * iATU Unroll-specific register definitions
  * From 4.80 core version the address translation will be made by unroll
@@ -279,6 +282,28 @@ static inline u32 dw_pcie_readl_dbi2(struct dw_pcie *pci, u32 reg)
 	return __dw_pcie_read_dbi(pci, pci->dbi_base2, reg, 0x4);
 }
 
+static inline void dw_pcie_dbi_ro_wr_en(struct dw_pcie *pci)
+{
+	u32 reg;
+	u32 val;
+
+	reg = PCIE_MISC_CONTROL_1_OFF;
+	val = dw_pcie_readl_dbi(pci, reg);
+	val |= PCIE_DBI_RO_WR_EN;
+	dw_pcie_writel_dbi(pci, reg, val);
+}
+
+static inline void dw_pcie_dbi_ro_wr_dis(struct dw_pcie *pci)
+{
+	u32 reg;
+	u32 val;
+
+	reg = PCIE_MISC_CONTROL_1_OFF;
+	val = dw_pcie_readl_dbi(pci, reg);
+	val &= ~PCIE_DBI_RO_WR_EN;
+	dw_pcie_writel_dbi(pci, reg, val);
+}
+
 #ifdef CONFIG_PCIE_DW_HOST
 irqreturn_t dw_handle_msi_irq(struct pcie_port *pp);
 void dw_pcie_msi_init(struct pcie_port *pp);
-- 
2.14.1