PCI: Unify ECAM constants in native PCI Express drivers

Add ECAM-related constants to provide a set of standard constants
defining memory address shift values to the byte-level address that can
be used to access the PCI Express Configuration Space, and then move
native PCI Express controller drivers to use the newly introduced
definitions retiring driver-specific ones.

Refactor pci_ecam_map_bus() function to use newly added constants so
that limits to the bus, device function and offset (now limited to 4K as
per the specification) are in place to prevent the defective or
malicious caller from supplying incorrect configuration offset and thus
targeting the wrong device when accessing extended configuration space.

This refactor also allows for the ".bus_shift" initialisers to be
dropped when the user is not using a custom value as a default value
will be used as per the PCI Express Specification.

Thanks to Qian Cai <[e-mail]>, Michael Walle <[e-mail]>,
and Vladimir Oltean <[e-mail]> for reporting a pci_ecam_create()
issue with .bus_shift and to Vladimir for proposing the fix.

[bhelgaas: incorporate Vladimir's fix, update commit log]
Suggested-by: Bjorn Helgaas <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Tested-by: Michael Walle <[e-mail]>
Signed-off-by: Krzysztof Wilczyński <[e-mail]>
Signed-off-by: Lorenzo Pieralisi <[e-mail]>
Signed-off-by: Bjorn Helgaas <[e-mail]>
Reviewed-by: Jon Derrick <[e-mail]>
Reviewed-by: Bjorn Helgaas <[e-mail]>

drivers/pci/controller/dwc/pcie-al.c

···
 }
 
 const struct pci_ecam_ops al_pcie_ops = {
-	.bus_shift    = 20,
 	.init         =  al_pcie_init,
 	.pci_ops      = {
 		.map_bus    = al_pcie_map_bus,
···
 	struct al_pcie_reg_offsets reg_offsets;
 	struct al_pcie_target_bus_cfg target_bus_cfg;
 };
-
-#define PCIE_ECAM_DEVFN(x)		(((x) & 0xff) << 12)
 
 #define to_al_pcie(x)		dev_get_drvdata((x)->dev)
 
···
 	struct al_pcie_target_bus_cfg *target_bus_cfg = &pcie->target_bus_cfg;
 	unsigned int busnr_ecam = busnr & target_bus_cfg->ecam_mask;
 	unsigned int busnr_reg = busnr & target_bus_cfg->reg_mask;
-	void __iomem *pci_base_addr;
-
-	pci_base_addr = (void __iomem *)((uintptr_t)pp->va_cfg0_base +
-					 (busnr_ecam << 20) +
-					 PCIE_ECAM_DEVFN(devfn));
 
 	if (busnr_reg != target_bus_cfg->reg_val) {
 		dev_dbg(pcie->pci->dev, "Changing target bus busnum val from 0x%x to 0x%x\n",
···
 				       target_bus_cfg->reg_mask);
 	}
 
-	return pci_base_addr + where;
+	return pp->va_cfg0_base + PCIE_ECAM_OFFSET(busnr_ecam, devfn, where);
 }
 
 static struct pci_ops al_child_pci_ops = {
···
 
 	target_bus_cfg = &pcie->target_bus_cfg;
 
-	ecam_bus_mask = (pcie->ecam_size >> 20) - 1;
+	ecam_bus_mask = (pcie->ecam_size >> PCIE_ECAM_BUS_SHIFT) - 1;
 	if (ecam_bus_mask > 255) {
 		dev_warn(pcie->dev, "ECAM window size is larger than 256MB. Cutting off at 256\n");
 		ecam_bus_mask = 255;

drivers/pci/controller/dwc/pcie-hisi.c

···
 }
 
 const struct pci_ecam_ops hisi_pcie_ops = {
-	.bus_shift    = 20,
 	.init         =  hisi_pcie_init,
 	.pci_ops      = {
 		.map_bus    = hisi_pcie_map_bus,
···
 }
 
 static const struct pci_ecam_ops hisi_pcie_platform_ops = {
-	.bus_shift    = 20,
 	.init         =  hisi_pcie_platform_init,
 	.pci_ops      = {
 		.map_bus    = hisi_pcie_map_bus,

drivers/pci/controller/pci-aardvark.c

···
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/pci.h>
+#include <linux/pci-ecam.h>
 #include <linux/init.h>
 #include <linux/phy/phy.h>
 #include <linux/platform_device.h>
···
 #define PCIE_CONFIG_RD_TYPE1			0x9
 #define PCIE_CONFIG_WR_TYPE0			0xa
 #define PCIE_CONFIG_WR_TYPE1			0xb
-
-#define PCIE_CONF_BUS(bus)			(((bus) & 0xff) << 20)
-#define PCIE_CONF_DEV(dev)			(((dev) & 0x1f) << 15)
-#define PCIE_CONF_FUNC(fun)			(((fun) & 0x7)	<< 12)
-#define PCIE_CONF_REG(reg)			((reg) & 0xffc)
-#define PCIE_CONF_ADDR(bus, devfn, where)	\
-	(PCIE_CONF_BUS(bus) | PCIE_CONF_DEV(PCI_SLOT(devfn))	| \
-	 PCIE_CONF_FUNC(PCI_FUNC(devfn)) | PCIE_CONF_REG(where))
 
 #define PIO_RETRY_CNT			500
 #define PIO_RETRY_DELAY			2 /* 2 us*/
···
 	advk_writel(pcie, reg, PIO_CTRL);
 
 	/* Program the address registers */
-	reg = PCIE_CONF_ADDR(bus->number, devfn, where);
+	reg = ALIGN_DOWN(PCIE_ECAM_OFFSET(bus->number, devfn, where), 4);
 	advk_writel(pcie, reg, PIO_ADDR_LS);
 	advk_writel(pcie, 0, PIO_ADDR_MS);
 
···
 	advk_writel(pcie, reg, PIO_CTRL);
 
 	/* Program the address registers */
-	reg = PCIE_CONF_ADDR(bus->number, devfn, where);
+	reg = ALIGN_DOWN(PCIE_ECAM_OFFSET(bus->number, devfn, where), 4);
 	advk_writel(pcie, reg, PIO_ADDR_LS);
 	advk_writel(pcie, 0, PIO_ADDR_MS);
 

drivers/pci/controller/pci-host-generic.c

···
 }
 
 static const struct pci_ecam_ops pci_dw_ecam_bus_ops = {
-	.bus_shift	= 20,
 	.pci_ops	= {
 		.map_bus	= pci_dw_ecam_map_bus,
 		.read		= pci_generic_config_read,

drivers/pci/controller/pci-thunder-ecam.c

···
 }
 
 const struct pci_ecam_ops pci_thunder_ecam_ops = {
-	.bus_shift	= 20,
 	.pci_ops	= {
 		.map_bus        = pci_ecam_map_bus,
 		.read           = thunder_ecam_config_read,

drivers/pci/controller/pcie-brcmstb.c

···
 #include <linux/of_pci.h>
 #include <linux/of_platform.h>
 #include <linux/pci.h>
+#include <linux/pci-ecam.h>
 #include <linux/printk.h>
 #include <linux/reset.h>
 #include <linux/sizes.h>
···
 #define  MSI_INT_MASK_CLR		0x14
 
 #define PCIE_EXT_CFG_DATA				0x8000
-
 #define PCIE_EXT_CFG_INDEX				0x9000
-#define  PCIE_EXT_BUSNUM_SHIFT				20
-#define  PCIE_EXT_SLOT_SHIFT				15
-#define  PCIE_EXT_FUNC_SHIFT				12
 
 #define  PCIE_RGR1_SW_INIT_1_PERST_MASK			0x1
 #define  PCIE_RGR1_SW_INIT_1_PERST_SHIFT		0x0
···
 	return dla && plu;
 }
 
-/* Configuration space read/write support */
-static inline int brcm_pcie_cfg_index(int busnr, int devfn, int reg)
-{
-	return ((PCI_SLOT(devfn) & 0x1f) << PCIE_EXT_SLOT_SHIFT)
-		| ((PCI_FUNC(devfn) & 0x07) << PCIE_EXT_FUNC_SHIFT)
-		| (busnr << PCIE_EXT_BUSNUM_SHIFT)
-		| (reg & ~3);
-}
-
 static void __iomem *brcm_pcie_map_conf(struct pci_bus *bus, unsigned int devfn,
 					int where)
 {
···
 		return PCI_SLOT(devfn) ? NULL : base + where;
 
 	/* For devices, write to the config space index register */
-	idx = brcm_pcie_cfg_index(bus->number, devfn, 0);
+	idx = PCIE_ECAM_OFFSET(bus->number, devfn, 0);
 	writel(idx, pcie->base + PCIE_EXT_CFG_INDEX);
 	return base + PCIE_EXT_CFG_DATA + where;
 }

drivers/pci/controller/pcie-rockchip-host.c

···
 				       struct pci_bus *bus, u32 devfn,
 				       int where, int size, u32 *val)
 {
-	u32 busdev;
+	void __iomem *addr;
 
-	busdev = PCIE_ECAM_ADDR(bus->number, PCI_SLOT(devfn),
-				PCI_FUNC(devfn), where);
+	addr = rockchip->reg_base + PCIE_ECAM_OFFSET(bus->number, devfn, where);
 
-	if (!IS_ALIGNED(busdev, size)) {
+	if (!IS_ALIGNED((uintptr_t)addr, size)) {
 		*val = 0;
 		return PCIBIOS_BAD_REGISTER_NUMBER;
 	}
···
 						AXI_WRAPPER_TYPE1_CFG);
 
 	if (size == 4) {
-		*val = readl(rockchip->reg_base + busdev);
+		*val = readl(addr);
 	} else if (size == 2) {
-		*val = readw(rockchip->reg_base + busdev);
+		*val = readw(addr);
 	} else if (size == 1) {
-		*val = readb(rockchip->reg_base + busdev);
+		*val = readb(addr);
 	} else {
 		*val = 0;
 		return PCIBIOS_BAD_REGISTER_NUMBER;
···
 				       struct pci_bus *bus, u32 devfn,
 				       int where, int size, u32 val)
 {
-	u32 busdev;
+	void __iomem *addr;
 
-	busdev = PCIE_ECAM_ADDR(bus->number, PCI_SLOT(devfn),
-				PCI_FUNC(devfn), where);
-	if (!IS_ALIGNED(busdev, size))
+	addr = rockchip->reg_base + PCIE_ECAM_OFFSET(bus->number, devfn, where);
+
+	if (!IS_ALIGNED((uintptr_t)addr, size))
 		return PCIBIOS_BAD_REGISTER_NUMBER;
 
 	if (pci_is_root_bus(bus->parent))
···
 						AXI_WRAPPER_TYPE1_CFG);
 
 	if (size == 4)
-		writel(val, rockchip->reg_base + busdev);
+		writel(val, addr);
 	else if (size == 2)
-		writew(val, rockchip->reg_base + busdev);
+		writew(val, addr);
 	else if (size == 1)
-		writeb(val, rockchip->reg_base + busdev);
+		writeb(val, addr);
 	else
 		return PCIBIOS_BAD_REGISTER_NUMBER;
 

drivers/pci/controller/pcie-rockchip.h

···
 
 #include <linux/kernel.h>
 #include <linux/pci.h>
+#include <linux/pci-ecam.h>
 
 /*
  * The upper 16 bits of PCIE_CLIENT_CONFIG are a write mask for the lower 16
···
 #define MIN_AXI_ADDR_BITS_PASSED		8
 #define PCIE_RC_SEND_PME_OFF			0x11960
 #define ROCKCHIP_VENDOR_ID			0x1d87
-#define PCIE_ECAM_BUS(x)			(((x) & 0xff) << 20)
-#define PCIE_ECAM_DEV(x)			(((x) & 0x1f) << 15)
-#define PCIE_ECAM_FUNC(x)			(((x) & 0x7) << 12)
-#define PCIE_ECAM_REG(x)			(((x) & 0xfff) << 0)
-#define PCIE_ECAM_ADDR(bus, dev, func, reg) \
-	  (PCIE_ECAM_BUS(bus) | PCIE_ECAM_DEV(dev) | \
-	   PCIE_ECAM_FUNC(func) | PCIE_ECAM_REG(reg))
 #define PCIE_LINK_IS_L2(x) \
 	(((x) & PCIE_CLIENT_DEBUG_LTSSM_MASK) == PCIE_CLIENT_DEBUG_LTSSM_L2)
 #define PCIE_LINK_UP(x) \

drivers/pci/controller/pcie-tango.c

···
 }
 
 static const struct pci_ecam_ops smp8759_ecam_ops = {
-	.bus_shift	= 20,
 	.pci_ops	= {
 		.map_bus	= pci_ecam_map_bus,
 		.read		= smp8759_config_read,

drivers/pci/controller/pcie-xilinx-nwl.c

···
 #include <linux/of_platform.h>
 #include <linux/of_irq.h>
 #include <linux/pci.h>
+#include <linux/pci-ecam.h>
 #include <linux/platform_device.h>
 #include <linux/irqchip/chained_irq.h>
 
···
 #define E_ECAM_CR_ENABLE		BIT(0)
 #define E_ECAM_SIZE_LOC			GENMASK(20, 16)
 #define E_ECAM_SIZE_SHIFT		16
-#define ECAM_BUS_LOC_SHIFT		20
-#define ECAM_DEV_LOC_SHIFT		12
 #define NWL_ECAM_VALUE_DEFAULT		12
 
 #define CFG_DMA_REG_BAR			GENMASK(2, 0)
···
 				      int where)
 {
 	struct nwl_pcie *pcie = bus->sysdata;
-	int relbus;
 
 	if (!nwl_pcie_valid_device(bus, devfn))
 		return NULL;
 
-	relbus = (bus->number << ECAM_BUS_LOC_SHIFT) |
-			(devfn << ECAM_DEV_LOC_SHIFT);
-
-	return pcie->ecam_base + relbus + where;
+	return pcie->ecam_base + PCIE_ECAM_OFFSET(bus->number, devfn, where);
 }
 
 /* PCIe operations */

drivers/pci/controller/pcie-xilinx.c

···
 #include <linux/of_platform.h>
 #include <linux/of_irq.h>
 #include <linux/pci.h>
+#include <linux/pci-ecam.h>
 #include <linux/platform_device.h>
 
 #include "../pci.h"
···
 
 /* Phy Status/Control Register definitions */
 #define XILINX_PCIE_REG_PSCR_LNKUP	BIT(11)
-
-/* ECAM definitions */
-#define ECAM_BUS_NUM_SHIFT		20
-#define ECAM_DEV_NUM_SHIFT		12
 
 /* Number of MSI IRQs */
 #define XILINX_NUM_MSI_IRQS		128
···
 					 unsigned int devfn, int where)
 {
 	struct xilinx_pcie_port *port = bus->sysdata;
-	int relbus;
 
 	if (!xilinx_pcie_valid_device(bus, devfn))
 		return NULL;
 
-	relbus = (bus->number << ECAM_BUS_NUM_SHIFT) |
-		 (devfn << ECAM_DEV_NUM_SHIFT);
-
-	return port->reg_base + relbus + where;
+	return port->reg_base + PCIE_ECAM_OFFSET(bus->number, devfn, where);
 }
 
 /* PCIe operations */

drivers/pci/controller/vmd.c

···
 #include <linux/module.h>
 #include <linux/msi.h>
 #include <linux/pci.h>
+#include <linux/pci-ecam.h>
 #include <linux/srcu.h>
 #include <linux/rculist.h>
 #include <linux/rcupdate.h>
···
 static char __iomem *vmd_cfg_addr(struct vmd_dev *vmd, struct pci_bus *bus,
 				  unsigned int devfn, int reg, int len)
 {
-	char __iomem *addr = vmd->cfgbar +
-			     ((bus->number - vmd->busn_start) << 20) +
-			     (devfn << 12) + reg;
+	unsigned int busnr_ecam = bus->number - vmd->busn_start;
+	u32 offset = PCIE_ECAM_OFFSET(busnr_ecam, devfn, reg);
 
-	if ((addr - vmd->cfgbar) + len >=
-	    resource_size(&vmd->dev->resource[VMD_CFGBAR]))
+	if (offset + len >= resource_size(&vmd->dev->resource[VMD_CFGBAR]))
 		return NULL;
 
-	return addr;
+	return vmd->cfgbar + offset;
 }
 
 /*

drivers/pci/ecam.c

···
 		struct resource *cfgres, struct resource *busr,
 		const struct pci_ecam_ops *ops)
 {
+	unsigned int bus_shift = ops->bus_shift;
 	struct pci_config_window *cfg;
 	unsigned int bus_range, bus_range_max, bsz;
 	struct resource *conflict;
···
 	if (!cfg)
 		return ERR_PTR(-ENOMEM);
 
+	/* ECAM-compliant platforms need not supply ops->bus_shift */
+	if (!bus_shift)
+		bus_shift = PCIE_ECAM_BUS_SHIFT;
+
 	cfg->parent = dev;
 	cfg->ops = ops;
 	cfg->busr.start = busr->start;
 	cfg->busr.end = busr->end;
 	cfg->busr.flags = IORESOURCE_BUS;
 	bus_range = resource_size(&cfg->busr);
-	bus_range_max = resource_size(cfgres) >> ops->bus_shift;
+	bus_range_max = resource_size(cfgres) >> bus_shift;
 	if (bus_range > bus_range_max) {
 		bus_range = bus_range_max;
 		cfg->busr.end = busr->start + bus_range - 1;
 		dev_warn(dev, "ECAM area %pR can only accommodate %pR (reduced from %pR desired)\n",
 			 cfgres, &cfg->busr, busr);
 	}
-	bsz = 1 << ops->bus_shift;
+	bsz = 1 << bus_shift;
 
 	cfg->res.start = cfgres->start;
 	cfg->res.end = cfgres->end;
···
 			       int where)
 {
 	struct pci_config_window *cfg = bus->sysdata;
+	unsigned int bus_shift = cfg->ops->bus_shift;
 	unsigned int devfn_shift = cfg->ops->bus_shift - 8;
 	unsigned int busn = bus->number;
 	void __iomem *base;
+	u32 bus_offset, devfn_offset;
 
 	if (busn < cfg->busr.start || busn > cfg->busr.end)
 		return NULL;
 
 	busn -= cfg->busr.start;
-	if (per_bus_mapping)
+	if (per_bus_mapping) {
 		base = cfg->winp[busn];
-	else
-		base = cfg->win + (busn << cfg->ops->bus_shift);
-	return base + (devfn << devfn_shift) + where;
+		busn = 0;
+	} else
+		base = cfg->win;
+
+	if (cfg->ops->bus_shift) {
+		bus_offset = (busn & PCIE_ECAM_BUS_MASK) << bus_shift;
+		devfn_offset = (devfn & PCIE_ECAM_DEVFN_MASK) << devfn_shift;
+		where &= PCIE_ECAM_REG_MASK;
+
+		return base + (bus_offset | devfn_offset | where);
+	}
+
+	return base + PCIE_ECAM_OFFSET(busn, devfn, where);
 }
 EXPORT_SYMBOL_GPL(pci_ecam_map_bus);
 
 /* ECAM ops */
 const struct pci_ecam_ops pci_generic_ecam_ops = {
-	.bus_shift	= 20,
 	.pci_ops	= {
 		.map_bus	= pci_ecam_map_bus,
 		.read		= pci_generic_config_read,
···
 #if defined(CONFIG_ACPI) && defined(CONFIG_PCI_QUIRKS)
 /* ECAM ops for 32-bit access only (non-compliant) */
 const struct pci_ecam_ops pci_32b_ops = {
-	.bus_shift	= 20,
 	.pci_ops	= {
 		.map_bus	= pci_ecam_map_bus,
 		.read		= pci_generic_config_read32,
···
 
 /* ECAM ops for 32-bit read only (non-compliant) */
 const struct pci_ecam_ops pci_32b_read_ops = {
-	.bus_shift	= 20,
 	.pci_ops	= {
 		.map_bus	= pci_ecam_map_bus,
 		.read		= pci_generic_config_read32,

include/linux/pci-ecam.h

···
 #include <linux/platform_device.h>
 
 /*
+ * Memory address shift values for the byte-level address that
+ * can be used when accessing the PCI Express Configuration Space.
+ */
+
+/*
+ * Enhanced Configuration Access Mechanism (ECAM)
+ *
+ * See PCI Express Base Specification, Revision 5.0, Version 1.0,
+ * Section 7.2.2, Table 7-1, p. 677.
+ */
+#define PCIE_ECAM_BUS_SHIFT	20 /* Bus number */
+#define PCIE_ECAM_DEVFN_SHIFT	12 /* Device and Function number */
+
+#define PCIE_ECAM_BUS_MASK	0xff
+#define PCIE_ECAM_DEVFN_MASK	0xff
+#define PCIE_ECAM_REG_MASK	0xfff /* Limit offset to a maximum of 4K */
+
+#define PCIE_ECAM_BUS(x)	(((x) & PCIE_ECAM_BUS_MASK) << PCIE_ECAM_BUS_SHIFT)
+#define PCIE_ECAM_DEVFN(x)	(((x) & PCIE_ECAM_DEVFN_MASK) << PCIE_ECAM_DEVFN_SHIFT)
+#define PCIE_ECAM_REG(x)	((x) & PCIE_ECAM_REG_MASK)
+
+#define PCIE_ECAM_OFFSET(bus, devfn, where) \
+	(PCIE_ECAM_BUS(bus) | \
+	 PCIE_ECAM_DEVFN(devfn) | \
+	 PCIE_ECAM_REG(where))
+
+/*
  * struct to hold pci ops and bus shift of the config window
  * for a PCI controller.
  */