linux-kernel - [PATCH v2 06/14] PCI: cadence: Add read/write accessors to perform only 32-bit accesses

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Message-ID: <20200106102058.19183-7-kishon@ti.com>
Date:   Mon, 6 Jan 2020 15:50:50 +0530
From:   Kishon Vijay Abraham I <kishon@...com>
To:     Kishon Vijay Abraham I <kishon@...com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Andrew Murray <andrew.murray@....com>
CC:     <linux-pci@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: [PATCH v2 06/14] PCI: cadence: Add read/write accessors to perform only 32-bit accesses

Certain platforms like TI's J721E allow only 32-bit register accesses.
Add read and write accessors to perform only 32-bit accesses in order to
support platforms like TI's J721E.

Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
---
 drivers/pci/controller/cadence/pcie-cadence.c | 40 +++++++++++++++++++
 drivers/pci/controller/cadence/pcie-cadence.h |  2 +
 2 files changed, 42 insertions(+)

diff --git a/drivers/pci/controller/cadence/pcie-cadence.c b/drivers/pci/controller/cadence/pcie-cadence.c
index cd795f6fc1e2..874b7fa93577 100644
--- a/drivers/pci/controller/cadence/pcie-cadence.c
+++ b/drivers/pci/controller/cadence/pcie-cadence.c
@@ -7,6 +7,46 @@
 
 #include "pcie-cadence.h"
 
+u32 cdns_platform_pcie_read32(void __iomem *addr, int size)
+{
+	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);
+}
+
+void cdns_platform_pcie_write32(void __iomem *addr, int size, u32 value)
+{
+	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);
+}
+
 void cdns_pcie_set_outbound_region(struct cdns_pcie *pcie, u8 fn,
 				   u32 r, bool is_io,
 				   u64 cpu_addr, u64 pci_addr, size_t size)
diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
index 676a57b7ad3d..31d031b07661 100644
--- a/drivers/pci/controller/cadence/pcie-cadence.h
+++ b/drivers/pci/controller/cadence/pcie-cadence.h
@@ -515,6 +515,8 @@ void cdns_pcie_reset_outbound_region(struct cdns_pcie *pcie, u32 r);
 void cdns_pcie_disable_phy(struct cdns_pcie *pcie);
 int cdns_pcie_enable_phy(struct cdns_pcie *pcie);
 int cdns_pcie_init_phy(struct device *dev, struct cdns_pcie *pcie);
+u32 cdns_platform_pcie_read32(void __iomem *addr, int size);
+void cdns_platform_pcie_write32(void __iomem *addr, int size, u32 value);
 extern const struct dev_pm_ops cdns_pcie_pm_ops;
 
 #endif /* _PCIE_CADENCE_H */
-- 
2.17.1