PCI: designware-ep: Fix ->get_msi() to check MSI_EN bit

->get_msi() now checks MSI_EN bit in the MSI CAPABILITY register to
find whether the host supports MSI instead of using the
MSI ADDRESS in the MSI CAPABILITY register.

This fixes the issue with the following sequence
  'modprobe pci_endpoint_test' enables MSI
  'rmmod pci_endpoint_test' disables MSI but MSI address (in EP's
	capability register) has a valid value
  'modprobe pci_endpoint_test no_msi=1' - Since MSI address (in EP's
	capability register) has a valid value (set during the previous
	insertion of the module), EP thinks host supports MSI.

Fixes: f8aed6ec624f ("PCI: dwc: designware: Add EP mode support")
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

2 files changed, 4 insertions, 9 deletions

diff --git a/drivers/pci/dwc/pcie-designware-ep.c b/drivers/pci/dwc/pcie-designware-ep.c
index d5eb143040e3..0989946df32c 100644
--- a/drivers/pci/dwc/pcie-designware-ep.c
+++ b/drivers/pci/dwc/pcie-designware-ep.c
@@ -195,20 +195,14 @@ static int dw_pcie_ep_map_addr(struct pci_epc *epc, phys_addr_t addr,
 static int dw_pcie_ep_get_msi(struct pci_epc *epc)
 {
         int val;
-        u32 lower_addr;
-        u32 upper_addr;
         struct dw_pcie_ep *ep = epc_get_drvdata(epc);
         struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
 
-        val = dw_pcie_readb_dbi(pci, MSI_MESSAGE_CONTROL);
-        val = (val & MSI_CAP_MME_MASK) >> MSI_CAP_MME_SHIFT;
-
-        lower_addr = dw_pcie_readl_dbi(pci, MSI_MESSAGE_ADDR_L32);
-        upper_addr = dw_pcie_readl_dbi(pci, MSI_MESSAGE_ADDR_U32);
-
-        if (!(lower_addr || upper_addr))
+        val = dw_pcie_readw_dbi(pci, MSI_MESSAGE_CONTROL);
+        if (!(val & MSI_CAP_MSI_EN_MASK))
                 return -EINVAL;
 
+        val = (val & MSI_CAP_MME_MASK) >> MSI_CAP_MME_SHIFT;
         return val;
 }
 
diff --git a/drivers/pci/dwc/pcie-designware.h b/drivers/pci/dwc/pcie-designware.h
index e6fd0b024b21..8700ba12c130 100644
--- a/drivers/pci/dwc/pcie-designware.h
+++ b/drivers/pci/dwc/pcie-designware.h
@@ -101,6 +101,7 @@
 #define MSI_MESSAGE_CONTROL             0x52
 #define MSI_CAP_MMC_SHIFT               1
 #define MSI_CAP_MME_SHIFT               4
+#define MSI_CAP_MSI_EN_MASK             0x1
 #define MSI_CAP_MME_MASK                (7 << MSI_CAP_MME_SHIFT)
 #define MSI_MESSAGE_ADDR_L32            0x54
 #define MSI_MESSAGE_ADDR_U32            0x58