linux-kernel - Re: [RFC PATCH 1/9] pci_ids: Add class code and extended capability for RCEC

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Date:   Mon, 27 Jul 2020 11:00:10 +0100
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Sean V Kelley <sean.v.kelley@...el.com>
CC:     <bhelgaas@...gle.com>, <rjw@...ysocki.net>, <ashok.raj@...nel.org>,
        <tony.luck@...el.com>,
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        <linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Qiuxu Zhuo <qiuxu.zhuo@...el.com>
Subject: Re: [RFC PATCH 1/9] pci_ids: Add class code and extended capability
 for RCEC

On Fri, 24 Jul 2020 10:22:15 -0700
Sean V Kelley <sean.v.kelley@...el.com> wrote:

> From: Qiuxu Zhuo <qiuxu.zhuo@...el.com>
> 
> A PCIe Root Complex Event Collector(RCEC) has the base class 0x08,
> sub-class 0x07, and programming interface 0x00. Add the class code
> 0x0807 to identify RCEC devices and add the defines for the RCEC
> Endpoint Association Extended Capability.
> 
> See PCI Express Base Specification, version 5.0-1, section "1.3.4
> Root Complex Event Collector" and section "7.9.10 Root Complex
> Event Collector Endpoint Association Extended Capability"

Add a reference to the document
"PCI Code and ID Assignment Specification"
for the class number.

>From the change log on latest version seems like it's been there since
version 1.4.

There is a worrying note (bottom of page 16 of 1.12 version of that docs)
in there that says some older specs used 0x0806 for RCECs and that we
should use the port type field to actually check if we have one.

Hopefully we won't encounter any of those in the wild.

Otherwise, it's exactly what the spec says.
We could bike shed on naming choices, but the ones you have seem clear enough
to me.

FWIW
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>


Jonathan
> 
> Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@...el.com>
> ---
>  include/linux/pci_ids.h       | 1 +
>  include/uapi/linux/pci_regs.h | 7 +++++++
>  2 files changed, 8 insertions(+)
> 
> diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h
> index 0ad57693f392..de8dff1fb176 100644
> --- a/include/linux/pci_ids.h
> +++ b/include/linux/pci_ids.h
> @@ -81,6 +81,7 @@
>  #define PCI_CLASS_SYSTEM_RTC		0x0803
>  #define PCI_CLASS_SYSTEM_PCI_HOTPLUG	0x0804
>  #define PCI_CLASS_SYSTEM_SDHCI		0x0805
> +#define PCI_CLASS_SYSTEM_RCEC		0x0807
>  #define PCI_CLASS_SYSTEM_OTHER		0x0880
>  
>  #define PCI_BASE_CLASS_INPUT		0x09
> diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
> index f9701410d3b5..f335f65f65d6 100644
> --- a/include/uapi/linux/pci_regs.h
> +++ b/include/uapi/linux/pci_regs.h
> @@ -828,6 +828,13 @@
>  #define  PCI_PWR_CAP_BUDGET(x)	((x) & 1)	/* Included in system budget */
>  #define PCI_EXT_CAP_PWR_SIZEOF	16
>  
> +/* Root Complex Event Collector Endpoint Association  */
> +#define PCI_RCEC_RCIEP_BITMAP	4	/* Associated Bitmap for RCiEPs */
> +#define PCI_RCEC_BUSN		8	/* RCEC Associated Bus Numbers */
> +#define  PCI_RCEC_BUSN_REG_VER	0x02	/* Least capability version that BUSN present */
> +#define  PCI_RCEC_BUSN_NEXT(x)	(((x) >> 8) & 0xff)
> +#define  PCI_RCEC_BUSN_LAST(x)	(((x) >> 16) & 0xff)
> +
>  /* Vendor-Specific (VSEC, PCI_EXT_CAP_ID_VNDR) */
>  #define PCI_VNDR_HEADER		4	/* Vendor-Specific Header */
>  #define  PCI_VNDR_HEADER_ID(x)	((x) & 0xffff)