linux-kernel - [PATCH v5 03/14] PCI: cadence: Convert all r/w accessors to perform only 32-bit accesses

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Date:   Fri, 22 May 2020 09:06:20 +0530
From:   Kishon Vijay Abraham I <kishon@...com>
To:     Tom Joseph <tjoseph@...ence.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>
CC:     <linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        <devicetree@...r.kernel.org>, <linux-omap@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        Kishon Vijay Abraham I <kishon@...com>
Subject: [PATCH v5 03/14] PCI: cadence: Convert all r/w accessors to perform only 32-bit accesses

Certain platforms like TI's J721E using Cadence PCIe IP can perform only
32-bit accesses for reading or writing to Cadence registers. Convert all
read and write accesses to 32-bit in Cadence PCIe driver in preparation
for adding PCIe support in TI's J721E SoC.

Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
---
 drivers/pci/controller/cadence/pcie-cadence.h | 71 ++++++++++++++-----
 1 file changed, 53 insertions(+), 18 deletions(-)

diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
index bc49c22e48a9..737e9561092b 100644
--- a/drivers/pci/controller/cadence/pcie-cadence.h
+++ b/drivers/pci/controller/cadence/pcie-cadence.h
@@ -319,50 +319,88 @@ struct cdns_pcie_ep {
 
 
 /* Register access */
-static inline void cdns_pcie_writeb(struct cdns_pcie *pcie, u32 reg, u8 value)
+static inline void cdns_pcie_writel(struct cdns_pcie *pcie, u32 reg, u32 value)
 {
-	writeb(value, pcie->reg_base + reg);
+	writel(value, pcie->reg_base + reg);
 }
 
-static inline void cdns_pcie_writew(struct cdns_pcie *pcie, u32 reg, u16 value)
+static inline u32 cdns_pcie_readl(struct cdns_pcie *pcie, u32 reg)
 {
-	writew(value, pcie->reg_base + reg);
+	return readl(pcie->reg_base + reg);
 }
 
-static inline void cdns_pcie_writel(struct cdns_pcie *pcie, u32 reg, u32 value)
+static inline u32 cdns_pcie_read_sz(void __iomem *addr, int size)
 {
-	writel(value, pcie->reg_base + reg);
+	void __iomem *aligned_addr = PTR_ALIGN_DOWN(addr, 0x4);
+	unsigned int offset = (unsigned long)addr & 0x3;
+	u32 val = readl(aligned_addr);
+
+	if (!IS_ALIGNED((uintptr_t)addr, size)) {
+		WARN(1, "Address %p and size %d are not aligned\n", addr, size);
+		return 0;
+	}
+
+	if (size > 2)
+		return val;
+
+	return (val >> (8 * offset)) & ((1 << (size * 8)) - 1);
 }
 
-static inline u32 cdns_pcie_readl(struct cdns_pcie *pcie, u32 reg)
+static inline void cdns_pcie_write_sz(void __iomem *addr, int size, u32 value)
 {
-	return readl(pcie->reg_base + reg);
+	void __iomem *aligned_addr = PTR_ALIGN_DOWN(addr, 0x4);
+	unsigned int offset = (unsigned long)addr & 0x3;
+	u32 mask;
+	u32 val;
+
+	if (!IS_ALIGNED((uintptr_t)addr, size)) {
+		WARN(1, "Address %p and size %d are not aligned\n", addr, size);
+		return;
+	}
+
+	if (size > 2) {
+		writel(value, addr);
+		return;
+	}
+
+	mask = ~(((1 << (size * 8)) - 1) << (offset * 8));
+	val = readl(aligned_addr) & mask;
+	val |= value << (offset * 8);
+	writel(val, aligned_addr);
 }
 
 /* Root Port register access */
 static inline void cdns_pcie_rp_writeb(struct cdns_pcie *pcie,
 				       u32 reg, u8 value)
 {
-	writeb(value, pcie->reg_base + CDNS_PCIE_RP_BASE + reg);
+	void __iomem *addr = pcie->reg_base + CDNS_PCIE_RP_BASE + reg;
+
+	cdns_pcie_write_sz(addr, 0x1, value);
 }
 
 static inline void cdns_pcie_rp_writew(struct cdns_pcie *pcie,
 				       u32 reg, u16 value)
 {
-	writew(value, pcie->reg_base + CDNS_PCIE_RP_BASE + reg);
+	void __iomem *addr = pcie->reg_base + CDNS_PCIE_RP_BASE + reg;
+
+	cdns_pcie_write_sz(addr, 0x2, value);
 }
 
 /* Endpoint Function register access */
 static inline void cdns_pcie_ep_fn_writeb(struct cdns_pcie *pcie, u8 fn,
 					  u32 reg, u8 value)
 {
-	writeb(value, pcie->reg_base + CDNS_PCIE_EP_FUNC_BASE(fn) + reg);
+	void __iomem *addr = pcie->reg_base + CDNS_PCIE_EP_FUNC_BASE(fn) + reg;
+
+	cdns_pcie_write_sz(addr, 0x1, value);
 }
 
 static inline void cdns_pcie_ep_fn_writew(struct cdns_pcie *pcie, u8 fn,
 					  u32 reg, u16 value)
 {
-	writew(value, pcie->reg_base + CDNS_PCIE_EP_FUNC_BASE(fn) + reg);
+	void __iomem *addr = pcie->reg_base + CDNS_PCIE_EP_FUNC_BASE(fn) + reg;
+
+	cdns_pcie_write_sz(addr, 0x2, value);
 }
 
 static inline void cdns_pcie_ep_fn_writel(struct cdns_pcie *pcie, u8 fn,
@@ -371,14 +409,11 @@ static inline void cdns_pcie_ep_fn_writel(struct cdns_pcie *pcie, u8 fn,
 	writel(value, pcie->reg_base + CDNS_PCIE_EP_FUNC_BASE(fn) + reg);
 }
 
-static inline u8 cdns_pcie_ep_fn_readb(struct cdns_pcie *pcie, u8 fn, u32 reg)
-{
-	return readb(pcie->reg_base + CDNS_PCIE_EP_FUNC_BASE(fn) + reg);
-}
-
 static inline u16 cdns_pcie_ep_fn_readw(struct cdns_pcie *pcie, u8 fn, u32 reg)
 {
-	return readw(pcie->reg_base + CDNS_PCIE_EP_FUNC_BASE(fn) + reg);
+	void __iomem *addr = pcie->reg_base + CDNS_PCIE_EP_FUNC_BASE(fn) + reg;
+
+	return cdns_pcie_read_sz(addr, 0x2);
 }
 
 static inline u32 cdns_pcie_ep_fn_readl(struct cdns_pcie *pcie, u8 fn, u32 reg)
-- 
2.17.1