Re: [PATCH V7 05/15] PCI: dwc: Add ext config space capability search API

From: Vidya Sagar
Date: Tue May 21 2019 - 13:17:09 EST


On 5/21/2019 4:06 PM, Thierry Reding wrote:
On Fri, May 17, 2019 at 06:08:36PM +0530, Vidya Sagar wrote:
Add extended configuration space capability search API using struct dw_pcie *
pointer

Signed-off-by: Vidya Sagar <vidyas@xxxxxxxxxx>
Acked-by: Gustavo Pimentel <gustavo.pimentel@xxxxxxxxxxxx>
---
Changes since [v6]:
* None

Changes since [v5]:
* None

Changes since [v4]:
* None

Changes since [v3]:
* None

Changes since [v2]:
* None

Changes since [v1]:
* This is a new patch in v2 series

drivers/pci/controller/dwc/pcie-designware.c | 41 ++++++++++++++++++++
drivers/pci/controller/dwc/pcie-designware.h | 1 +
2 files changed, 42 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index 8f53ce63d17e..3b7d50888caa 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -54,6 +54,47 @@ u8 dw_pcie_find_capability(struct dw_pcie *pci, u8 cap)
}
EXPORT_SYMBOL_GPL(dw_pcie_find_capability);
+static int dw_pcie_find_next_ext_capability(struct dw_pcie *pci, int start,
+ int cap)

Perhaps make this more consistent with the existing regular
configuration space capability search API? Something like this perhaps:

static u16 dw_pcie_find_next_ext_capability(struct dw_pcie *pci,
u16 start, u8 cap)

? I guess your variant above is consistent with the existing generic
capability search API, so another alternative might be to make the old
dw_pcie_find_capability() API consistent with everything else. It's
confusing if we keep having to jump between the two variants.
Ok. I'll change it to the format being followed in this file i.e. using u16 and u8


Thierry

+{
+ 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;
+}
+
+int dw_pcie_find_ext_capability(struct dw_pcie *pci, int 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 6cb978132469..fff284098117 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);
+int dw_pcie_find_ext_capability(struct dw_pcie *pci, int cap);
int dw_pcie_read(void __iomem *addr, int size, u32 *val);
int dw_pcie_write(void __iomem *addr, int size, u32 val);
--
2.17.1