linux-kernel - Re: [PATCH v2 08/10] PCI: Add FMT and TYPE definition for TLP header

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Message-ID: <20250715154145.GA2461632@bhelgaas>
Date: Tue, 15 Jul 2025 10:41:45 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Jacky Chou <jacky_chou@...eedtech.com>
Cc: bhelgaas@...gle.com, lpieralisi@...nel.org, kwilczynski@...nel.org,
	mani@...nel.org, robh@...nel.org, krzk+dt@...nel.org,
	conor+dt@...nel.org, joel@....id.au, andrew@...econstruct.com.au,
	linux-aspeed@...ts.ozlabs.org, linux-pci@...r.kernel.org,
	devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, openbmc@...ts.ozlabs.org,
	linux-gpio@...r.kernel.org, linus.walleij@...aro.org,
	p.zabel@...gutronix.de, BMC-SW@...eedtech.com
Subject: Re: [PATCH v2 08/10] PCI: Add FMT and TYPE definition for TLP header

On Tue, Jul 15, 2025 at 11:43:18AM +0800, Jacky Chou wrote:
> According to PCIe specification, add FMT and TYPE definition
> for TLP header. And also add macro to combine FMT and TYPE to
> 1 byte.
> 
> Signed-off-by: Jacky Chou <jacky_chou@...eedtech.com>
> ---
>  include/uapi/linux/pci_regs.h | 32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)

I don't think these definitions are relevant to uapi users, so they
could go in drivers/pci/pci.h, similar to the existing PCIE_MSG_*
definitions.

Please follow the style of PCIE_MSG_*, including the brief spec
citations and /* */ comments.

Not sure we need *all* of these; it looks like you only use:

  PCI_TLP_TYPE_CFG0_RD
  PCI_TLP_TYPE_CFG0_WR
  PCI_TLP_TYPE_CFG1_RD
  PCI_TLP_TYPE_CFG1_WR
  PCI_TLP_FMT_3DW_NO_DATA
  PCI_TLP_FMT_3DW_DATA

> diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
> index a3a3e942dedf..700b915e00f5 100644
> --- a/include/uapi/linux/pci_regs.h
> +++ b/include/uapi/linux/pci_regs.h
> @@ -1230,4 +1230,36 @@
>  #define PCI_DVSEC_CXL_PORT_CTL				0x0c
>  #define PCI_DVSEC_CXL_PORT_CTL_UNMASK_SBR		0x00000001
>  
> +/* Fmt[2:0] encoding for TLP Header */
> +#define PCI_TLP_FMT_3DW_NO_DATA		0x0  // 3DW header, no data
> +#define PCI_TLP_FMT_4DW_NO_DATA		0x1  // 4DW header, no data
> +#define PCI_TLP_FMT_3DW_DATA		0x2  // 3DW header, with data
> +#define PCI_TLP_FMT_4DW_DATA		0x3  // 4DW header, with data
> +#define PCI_TLP_FMT_PREFIX		0x4  // Prefix header
> +
> +/* Type[4:0] encoding for TLP Header */
> +#define PCI_TLP_TYPE_MEM_RD		0x00 // Memory Read Request
> +#define PCI_TLP_TYPE_MEM_RDLK		0x01 // Memory Read Lock Request
> +#define PCI_TLP_TYPE_MEM_WR		0x00 // Memory Write Request (Fmt must be with data)
> +#define PCI_TLP_TYPE_IO_RD		0x02 // IO Read Request
> +#define PCI_TLP_TYPE_IO_WR		0x02 // IO Write Request (Fmt must be with data)
> +#define PCI_TLP_TYPE_CFG0_RD		0x04 // Config Type 0 Read Request
> +#define PCI_TLP_TYPE_CFG0_WR		0x04 // Config Type 0 Write Request (Fmt must be with data)
> +#define PCI_TLP_TYPE_CFG1_RD		0x05 // Config Type 1 Read Request
> +#define PCI_TLP_TYPE_CFG1_WR		0x05 // Config Type 1 Write Request (Fmt must be with data)
> +#define PCI_TLP_TYPE_MSG		0x10 // Message Request (see routing field)
> +#define PCI_TLP_TYPE_MSGD		0x11 // Message Request with Data (see routing field)
> +#define PCI_TLP_TYPE_CPL		0x0A // Completion without Data
> +#define PCI_TLP_TYPE_CPLD		0x0A // Completion with Data (Fmt must be with data)
> +#define PCI_TLP_TYPE_CPLLCK		0x0B // Completion Locked
> +#define PCI_TLP_TYPE_CPLDLCK		0x0B // Completion with Data Locked (Fmt must be with data)
> +#define PCI_TLP_TYPE_FETCH_ADD		0x0C // Fetch and Add AtomicOp Request
> +#define PCI_TLP_TYPE_SWAP		0x0D // Unconditional Swap AtomicOp Request
> +#define PCI_TLP_TYPE_CMP_SWAP		0x0E // Compare and Swap AtomicOp Request
> +#define PCI_TLP_TYPE_LOCAL_PREFIX	0x00 // Local TLP Prefix (Fmt = 0x4)
> +#define PCI_TLP_TYPE_E2E_PREFIX		0x10 // End-to-End TLP Prefix (Fmt = 0x4)
> +
> +/* Macro to combine Fmt and Type into the 8-bit field */
> +#define PCIE_TLP_FMT_TYPE(fmt, type)   (((fmt) << 5) | ((type) & 0x1F))

This looks like it might be controller-specific and could go in
pcie-aspeed.c.