PCI: mobiveil: fix 5.7 merge errors

Fix errors in the mobiveil version that was merged in 5.7 kernels:
- the type of "root_bus_nr" was changed from "u8" to "char", but
  it is compared to values that are typed as "unsigned char".
  Depending whether a platform has "char" as signed or unsigned,
  this may not do what is intended.

- ls_pcie_g4_reinit_hw() now returns a success/failure value, and
  follows the Linux style of return 0 on success and -ve errno on
  failure.  However, the testing in ls_pcie_g4_reset() expects 0
  on failure, so we won't call ls_pcie_g4_enable_interrupt() except
  if ls_pcie_g4_reinit_hw() has failed - which is likely not what
  was intended.

Fixes: d29ad70a813b ("PCI: mobiveil: Add PCIe Gen4 RC driver for Layerscape SoCs")
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

1 files changed, 15 insertions, 1 deletions

diff --git a/drivers/pci/controller/mobiveil/pcie-layerscape-gen4.c b/drivers/pci/controller/mobiveil/pcie-layerscape-gen4.c
index ee0156921ebc..e00ed73c2355 100644
--- a/drivers/pci/controller/mobiveil/pcie-layerscape-gen4.c
+++ b/drivers/pci/controller/mobiveil/pcie-layerscape-gen4.c
@@ -64,6 +64,17 @@ static inline void ls_pcie_g4_pf_writel(struct ls_pcie_g4 *pcie,
 	iowrite32(val, pcie->pci.csr_axi_slave_base + PCIE_PF_OFF + off);
 }
 
+static bool ls_pcie_g4_is_bridge(struct ls_pcie_g4 *pcie)
+{
+	struct mobiveil_pcie *mv_pci = &pcie->pci;
+	u32 header_type;
+
+	header_type = mobiveil_csr_readb(mv_pci, PCI_HEADER_TYPE);
+	header_type &= 0x7f;
+
+	return header_type == PCI_HEADER_TYPE_BRIDGE;
+}
+
 static int ls_pcie_g4_link_up(struct mobiveil_pcie *pci)
 {
 	struct ls_pcie_g4 *pcie = to_ls_pcie_g4(pci);
@@ -195,7 +206,7 @@ static void ls_pcie_g4_reset(struct work_struct *work)
 	ctrl &= ~PCI_BRIDGE_CTL_BUS_RESET;
 	mobiveil_csr_writew(mv_pci, ctrl, PCI_BRIDGE_CONTROL);
 
-	if (!ls_pcie_g4_reinit_hw(pcie))
+	if (ls_pcie_g4_reinit_hw(pcie))
 		return;
 
 	ls_pcie_g4_enable_interrupt(pcie);
@@ -245,6 +256,9 @@ static int __init ls_pcie_g4_probe(struct platform_device *pdev)
 		return  ret;
 	}
 
+	if (!ls_pcie_g4_is_bridge(pcie))
+		return -ENODEV;
+
 	ls_pcie_g4_enable_interrupt(pcie);
 
 	return 0;