[PATCH v6 1/5] PCI: Unify ECAM constants in native PCI Express drivers

Lorenzo Pieralisi lorenzo.pieralisi at arm.com
Mon Nov 30 22:08:58 AEDT 2020


On Sun, Nov 29, 2020 at 11:07:39PM +0000, Krzysztof Wilczyński wrote:
> 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_shit" initialisers to be dropped
                                          ^^^^

Nice typo, I'd fix it while applying it though if you don't mind ;-),
no need to resend it.

Jokes aside, nice piece of work, thanks for that.

> when the user is not using a custom value as a default value will be
> used as per the PCI Express Specification.
> 
> Suggested-by: Bjorn Helgaas <bhelgaas at google.com>
> Signed-off-by: Krzysztof Wilczyński <kw at linux.com>

I think Bjorn's reviewed-by still stands so I will apply it.

Thanks !
Lorenzo

> ---
>  drivers/pci/controller/dwc/pcie-al.c        | 12 ++-------
>  drivers/pci/controller/dwc/pcie-hisi.c      |  2 --
>  drivers/pci/controller/pci-aardvark.c       | 13 +++-------
>  drivers/pci/controller/pci-host-generic.c   |  1 -
>  drivers/pci/controller/pci-thunder-ecam.c   |  1 -
>  drivers/pci/controller/pcie-brcmstb.c       | 16 ++----------
>  drivers/pci/controller/pcie-rockchip-host.c | 27 ++++++++++-----------
>  drivers/pci/controller/pcie-rockchip.h      |  8 +-----
>  drivers/pci/controller/pcie-tango.c         |  1 -
>  drivers/pci/controller/pcie-xilinx-nwl.c    |  9 ++-----
>  drivers/pci/controller/pcie-xilinx.c        | 11 ++-------
>  drivers/pci/controller/vmd.c                | 11 ++++-----
>  drivers/pci/ecam.c                          | 23 ++++++++++++------
>  include/linux/pci-ecam.h                    | 27 +++++++++++++++++++++
>  14 files changed, 73 insertions(+), 89 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-al.c b/drivers/pci/controller/dwc/pcie-al.c
> index f973fbca90cf..af9e51ab1af8 100644
> --- a/drivers/pci/controller/dwc/pcie-al.c
> +++ b/drivers/pci/controller/dwc/pcie-al.c
> @@ -76,7 +76,6 @@ static int al_pcie_init(struct pci_config_window *cfg)
>  }
>  
>  const struct pci_ecam_ops al_pcie_ops = {
> -	.bus_shift    = 20,
>  	.init         =  al_pcie_init,
>  	.pci_ops      = {
>  		.map_bus    = al_pcie_map_bus,
> @@ -138,8 +137,6 @@ struct al_pcie {
>  	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)
>  
>  static inline u32 al_pcie_controller_readl(struct al_pcie *pcie, u32 offset)
> @@ -226,11 +223,6 @@ static void __iomem *al_pcie_conf_addr_map_bus(struct pci_bus *bus,
>  	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",
> @@ -241,7 +233,7 @@ static void __iomem *al_pcie_conf_addr_map_bus(struct pci_bus *bus,
>  				       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 = {
> @@ -264,7 +256,7 @@ static void al_pcie_config_prepare(struct al_pcie *pcie)
>  
>  	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;
> diff --git a/drivers/pci/controller/dwc/pcie-hisi.c b/drivers/pci/controller/dwc/pcie-hisi.c
> index 5ca86796d43a..8fc5960faf28 100644
> --- a/drivers/pci/controller/dwc/pcie-hisi.c
> +++ b/drivers/pci/controller/dwc/pcie-hisi.c
> @@ -100,7 +100,6 @@ static int hisi_pcie_init(struct pci_config_window *cfg)
>  }
>  
>  const struct pci_ecam_ops hisi_pcie_ops = {
> -	.bus_shift    = 20,
>  	.init         =  hisi_pcie_init,
>  	.pci_ops      = {
>  		.map_bus    = hisi_pcie_map_bus,
> @@ -135,7 +134,6 @@ static int hisi_pcie_platform_init(struct pci_config_window *cfg)
>  }
>  
>  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,
> diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
> index 0be485a25327..1043e54c73bd 100644
> --- a/drivers/pci/controller/pci-aardvark.c
> +++ b/drivers/pci/controller/pci-aardvark.c
> @@ -16,6 +16,7 @@
>  #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>
> @@ -164,14 +165,6 @@
>  #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*/
>  
> @@ -687,7 +680,7 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn,
>  	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);
>  
> @@ -748,7 +741,7 @@ static int advk_pcie_wr_conf(struct pci_bus *bus, u32 devfn,
>  	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);
>  
> diff --git a/drivers/pci/controller/pci-host-generic.c b/drivers/pci/controller/pci-host-generic.c
> index b51977abfdf1..63865aeb636b 100644
> --- a/drivers/pci/controller/pci-host-generic.c
> +++ b/drivers/pci/controller/pci-host-generic.c
> @@ -49,7 +49,6 @@ static void __iomem *pci_dw_ecam_map_bus(struct pci_bus *bus,
>  }
>  
>  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,
> diff --git a/drivers/pci/controller/pci-thunder-ecam.c b/drivers/pci/controller/pci-thunder-ecam.c
> index 7e8835fee5f7..f964fd26f7e0 100644
> --- a/drivers/pci/controller/pci-thunder-ecam.c
> +++ b/drivers/pci/controller/pci-thunder-ecam.c
> @@ -346,7 +346,6 @@ static int thunder_ecam_config_write(struct pci_bus *bus, unsigned int devfn,
>  }
>  
>  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,
> diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
> index bea86899bd5d..7fc80fd6f13f 100644
> --- a/drivers/pci/controller/pcie-brcmstb.c
> +++ b/drivers/pci/controller/pcie-brcmstb.c
> @@ -22,6 +22,7 @@
>  #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>
> @@ -127,11 +128,7 @@
>  #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
> @@ -695,15 +692,6 @@ static bool brcm_pcie_link_up(struct brcm_pcie *pcie)
>  	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)
>  {
> @@ -716,7 +704,7 @@ static void __iomem *brcm_pcie_map_conf(struct pci_bus *bus, unsigned int devfn,
>  		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;
>  }
> diff --git a/drivers/pci/controller/pcie-rockchip-host.c b/drivers/pci/controller/pcie-rockchip-host.c
> index 9705059523a6..f1d08a1b1591 100644
> --- a/drivers/pci/controller/pcie-rockchip-host.c
> +++ b/drivers/pci/controller/pcie-rockchip-host.c
> @@ -157,12 +157,11 @@ static int rockchip_pcie_rd_other_conf(struct rockchip_pcie *rockchip,
>  				       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;
>  	}
> @@ -175,11 +174,11 @@ static int rockchip_pcie_rd_other_conf(struct rockchip_pcie *rockchip,
>  						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;
> @@ -191,11 +190,11 @@ static int rockchip_pcie_wr_other_conf(struct rockchip_pcie *rockchip,
>  				       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))
> @@ -206,11 +205,11 @@ static int rockchip_pcie_wr_other_conf(struct rockchip_pcie *rockchip,
>  						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;
>  
> diff --git a/drivers/pci/controller/pcie-rockchip.h b/drivers/pci/controller/pcie-rockchip.h
> index c7d0178fc8c2..1650a5087450 100644
> --- a/drivers/pci/controller/pcie-rockchip.h
> +++ b/drivers/pci/controller/pcie-rockchip.h
> @@ -13,6 +13,7 @@
>  
>  #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
> @@ -178,13 +179,6 @@
>  #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) \
> diff --git a/drivers/pci/controller/pcie-tango.c b/drivers/pci/controller/pcie-tango.c
> index d093a8ce4bb1..62a061f1d62e 100644
> --- a/drivers/pci/controller/pcie-tango.c
> +++ b/drivers/pci/controller/pcie-tango.c
> @@ -208,7 +208,6 @@ static int smp8759_config_write(struct pci_bus *bus, unsigned int devfn,
>  }
>  
>  static const struct pci_ecam_ops smp8759_ecam_ops = {
> -	.bus_shift	= 20,
>  	.pci_ops	= {
>  		.map_bus	= pci_ecam_map_bus,
>  		.read		= smp8759_config_read,
> diff --git a/drivers/pci/controller/pcie-xilinx-nwl.c b/drivers/pci/controller/pcie-xilinx-nwl.c
> index f3cf7d61924f..7f29c2fdcd51 100644
> --- a/drivers/pci/controller/pcie-xilinx-nwl.c
> +++ b/drivers/pci/controller/pcie-xilinx-nwl.c
> @@ -18,6 +18,7 @@
>  #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>
>  
> @@ -124,8 +125,6 @@
>  #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)
> @@ -240,15 +239,11 @@ static void __iomem *nwl_pcie_map_bus(struct pci_bus *bus, unsigned int devfn,
>  				      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 */
> diff --git a/drivers/pci/controller/pcie-xilinx.c b/drivers/pci/controller/pcie-xilinx.c
> index 8523be61bba5..fa5baeb82653 100644
> --- a/drivers/pci/controller/pcie-xilinx.c
> +++ b/drivers/pci/controller/pcie-xilinx.c
> @@ -21,6 +21,7 @@
>  #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"
> @@ -86,10 +87,6 @@
>  /* 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
>  
> @@ -183,15 +180,11 @@ static void __iomem *xilinx_pcie_map_bus(struct pci_bus *bus,
>  					 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 */
> diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
> index f375c21ceeb1..1361a79bd1e7 100644
> --- a/drivers/pci/controller/vmd.c
> +++ b/drivers/pci/controller/vmd.c
> @@ -11,6 +11,7 @@
>  #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>
> @@ -328,15 +329,13 @@ static void vmd_remove_irq_domain(struct vmd_dev *vmd)
>  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;
>  }
>  
>  /*
> diff --git a/drivers/pci/ecam.c b/drivers/pci/ecam.c
> index b54d32a31669..59f91d434859 100644
> --- a/drivers/pci/ecam.c
> +++ b/drivers/pci/ecam.c
> @@ -131,25 +131,36 @@ void __iomem *pci_ecam_map_bus(struct pci_bus *bus, unsigned int devfn,
>  			       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,
> @@ -161,7 +172,6 @@ EXPORT_SYMBOL_GPL(pci_generic_ecam_ops);
>  #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,
> @@ -171,7 +181,6 @@ const struct pci_ecam_ops pci_32b_ops = {
>  
>  /* 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,
> diff --git a/include/linux/pci-ecam.h b/include/linux/pci-ecam.h
> index 033ce74f02e8..65d3d83015c3 100644
> --- a/include/linux/pci-ecam.h
> +++ b/include/linux/pci-ecam.h
> @@ -9,6 +9,33 @@
>  #include <linux/kernel.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.
> -- 
> 2.29.2
> 


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