linux-kernel - [PATCH V2 06/16] PCI: dwc: Add ext config space capability search API

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Date:   Fri, 5 Apr 2019 01:24:33 +0530
From:   Vidya Sagar <vidyas@...dia.com>
To:     <bhelgaas@...gle.com>, <robh+dt@...nel.org>,
        <mark.rutland@....com>, <thierry.reding@...il.com>,
        <jonathanh@...dia.com>, <kishon@...com>, <catalin.marinas@....com>,
        <will.deacon@....com>, <lorenzo.pieralisi@....com>,
        <jingoohan1@...il.com>, <gustavo.pimentel@...opsys.com>,
        <mperttunen@...dia.com>
CC:     <linux-pci@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <kthota@...dia.com>,
        <mmaddireddy@...dia.com>, <vidyas@...dia.com>, <sagar.tv@...il.com>
Subject: [PATCH V2 06/16] PCI: dwc: Add ext config space capability search API

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

Signed-off-by: Vidya Sagar <vidyas@...dia.com>
---
Changes from [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 d68c123e409c..44c0ba078452 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)
 	return __dw_pcie_find_next_cap(pci, next_cap_ptr, cap);
 }
 
+static int dw_pcie_find_next_ext_capability(struct dw_pcie *pci, int start,
+					    int 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;
+}
+
+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 4ccd4c706ddb..fa41d675c48f 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -248,6 +248,7 @@ 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);
-- 
2.7.4