PCI: dwc: Add extended configuration space capability search API

Add extended configuration space capability search API using struct
dw_pcie* pointer.

Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
Acked-by: Thierry Reding <treding@nvidia.com>

2 files changed, 42 insertions, 0 deletions

diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index 7818b4febb08..181449e342f1 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -53,6 +53,47 @@ u8 dw_pcie_find_capability(struct dw_pcie *pci, u8 cap)
 }
 EXPORT_SYMBOL_GPL(dw_pcie_find_capability);
 
+static u16 dw_pcie_find_next_ext_capability(struct dw_pcie *pci, u16 start,
+                                            u8 cap)
+{
+        u32 header;
+        int ttl;
+        int pos = PCI_CFG_SPACE_SIZE;
+
+        /* minimum 8 bytes per capability */
+        ttl = (PCI_CFG_SPACE_EXP_SIZE - PCI_CFG_SPACE_SIZE) / 8;
+
+        if (start)
+                pos = start;
+
+        header = dw_pcie_readl_dbi(pci, pos);
+        /*
+         * If we have no capabilities, this is indicated by cap ID,
+         * cap version and next pointer all being 0.
+         */
+        if (header == 0)
+                return 0;
+
+        while (ttl-- > 0) {
+                if (PCI_EXT_CAP_ID(header) == cap && pos != start)
+                        return pos;
+
+                pos = PCI_EXT_CAP_NEXT(header);
+                if (pos < PCI_CFG_SPACE_SIZE)
+                        break;
+
+                header = dw_pcie_readl_dbi(pci, pos);
+        }
+
+        return 0;
+}
+
+u16 dw_pcie_find_ext_capability(struct dw_pcie *pci, u8 cap)
+{
+        return dw_pcie_find_next_ext_capability(pci, 0, cap);
+}
+EXPORT_SYMBOL_GPL(dw_pcie_find_ext_capability);
+
 int dw_pcie_read(void __iomem *addr, int size, u32 *val)
 {
         if (!IS_ALIGNED((uintptr_t)addr, size)) {
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index d8c66a6827dc..11c223471416 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -252,6 +252,7 @@ struct dw_pcie {
                 container_of((endpoint), struct dw_pcie, ep)
 
 u8 dw_pcie_find_capability(struct dw_pcie *pci, u8 cap);
+u16 dw_pcie_find_ext_capability(struct dw_pcie *pci, u8 cap);
 
 int dw_pcie_read(void __iomem *addr, int size, u32 *val);
 int dw_pcie_write(void __iomem *addr, int size, u32 val);