Re: [PATCH v2 1/5] x86/PCI: Add support for generic AMD hostbridges

[Borislav Petkov]

On Fri, Apr 18, 2014 at 08:53:16PM -0600, Myron Stowe wrote:
> From: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
> 
> AMD hostbridges gnenerally show up as PCI device 0:18.0.  This patch adds
> logic to automatically probe the device at this location and check PCI
> device class code.
> 
> This patch supports platforms with the following AMD hostbridge types:
> (K8, family10h, 11h, 12h, 14h 15h  and 16h processors).
> 
> Reference(s):
>   https://bugzilla.kernel.org/show_bug.cgi?id=72051
>   Advanced Micro Devices (AMD), "BIOS and Kernel Developer's
>   Guide (BKDG) for AMD Family 15h Models 00h-0fh Processors."  Section
>   3.4 Device [1F:18]h Function 1 Configuration Registers; D18F1x[EC:E0]
>   Configuration Map, 42301 Rev 3.12 - October 11, 2012.
> 
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
> Signed-off-by: Myron Stowe <myron.stowe@xxxxxxxxxx>
> Tested-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@xxxxxxx>
> ---
> 
>  arch/x86/pci/amd_bus.c |   71 ++++++++++++++++++++++++++++++++----------------
>  1 files changed, 47 insertions(+), 24 deletions(-)
> 
> diff --git a/arch/x86/pci/amd_bus.c b/arch/x86/pci/amd_bus.c
> index e88f4c5..c8cd75c 100644
> --- a/arch/x86/pci/amd_bus.c
> +++ b/arch/x86/pci/amd_bus.c
> @@ -11,27 +11,34 @@
>  
>  #include "bus_numa.h"
>  
> +#define AMD_NB_F0_NODE_ID			0x60
> +#define AMD_NB_F0_UNIT_ID			0x64
> +#define AMD_NB_F1_CONFIG_MAP_REG		0xe0
> +
> +#define RANGE_NUM				16
> +#define AMD_NB_F1_CONFIG_MAP_RANGES		4
> +
>  /*
> - * This discovers the pcibus <-> node mapping on AMD K8.
> - * also get peer root bus resource for io,mmio
> + * This discovers the pcibus <-> node mapping on AMD K8, Family 10h, 12h,
> + * 14h, 15h, and 16h processor based systems.  This also gets peer root bus
> + * resources corresponding to I/O and MMIO addresses.
>   */
>  
> -struct pci_hostbridge_probe {
> +struct amd_hostbridge {
>  	u32 bus;
>  	u32 slot;
> -	u32 vendor;
>  	u32 device;
>  };
>  
> -static struct pci_hostbridge_probe pci_probes[] __initdata = {
> -	{ 0, 0x18, PCI_VENDOR_ID_AMD, 0x1100 },
> -	{ 0, 0x18, PCI_VENDOR_ID_AMD, 0x1200 },
> -	{ 0xff, 0, PCI_VENDOR_ID_AMD, 0x1200 },
> -	{ 0, 0x18, PCI_VENDOR_ID_AMD, 0x1300 },
> +static struct amd_hostbridge hb_probes[] __initdata = {
> +	/* Standard AMD Hostbriges are at bus 0x0 slot 0x18.
> +	 * In case of PCI_ANY_ID, the logic will try matching
> +	 * PCI_CLASS_BRIDGE_HOST instead.
> +	 */

Standard kernel comment style:

/*
 * Something interesting for the code below.
 * This is the second comment line.
 */

> +	{ 0x0 , 0x18, PCI_ANY_ID },
> +	{ 0xff, 0   , PCI_DEVICE_ID_AMD_10H_NB_HT },
>  };
>  
> -#define RANGE_NUM 16
> -
>  static struct pci_root_info __init *find_pci_root_info(int node, int link)
>  {
>  	struct pci_root_info *info;
> @@ -75,31 +82,47 @@ static int __init early_fill_mp_bus_info(void)

Btw, this function is huuuge. It could use a splitup some day.

>  		return -1;
>  
>  	found = false;
> -	for (i = 0; i < ARRAY_SIZE(pci_probes); i++) {
> +	for (i = 0; i < ARRAY_SIZE(hb_probes); i++) {
>  		u32 id;
>  		u16 device;
>  		u16 vendor;
> +		u32 class;
>  
> -		bus = pci_probes[i].bus;
> -		slot = pci_probes[i].slot;
> +		bus = hb_probes[i].bus;
> +		slot = hb_probes[i].slot;
>  		id = read_pci_config(bus, slot, 0, PCI_VENDOR_ID);
> -
>  		vendor = id & 0xffff;
>  		device = (id>>16) & 0xffff;
> -		if (pci_probes[i].vendor == vendor &&
> -		    pci_probes[i].device == device) {
> -			found = true;
> -			break;
> +		class = read_pci_config(bus, slot, 0,
> +			PCI_CLASS_REVISION) >> 16;
> +
> +		if (PCI_VENDOR_ID_AMD == vendor) {

Flip comparison:

		if (vendor == PCI_VENDOR_ID_AMD)

and then save yourself another indentation level:

		if (vendor != PCI_VENDOR_ID_AMD)
			continue;

> +			if (hb_probes[i].device == device) {
> +				found = true;
> +				break;
> +			}
> +
> +			if ((hb_probes[i].device == PCI_ANY_ID) &&
> +			    (class == PCI_CLASS_BRIDGE_HOST)) {
> +				hb_probes[i].device = device;
> +				found = true;
> +				break;
> +			}
>  		}
>  	}
>  
> -	if (!found)
> +	if (!found) {
> +		pr_warn("AMD hostbridge not found\n");
>  		return 0;
> +	}

I guess this should return a negative value... Not that it matters much
from looking at the call site in the amd_postcore_init initcall.

>  
> -	for (i = 0; i < 4; i++) {
> +	pr_debug("Found AMD hostbridge at %x:%x.0\n", bus, slot);

Why not pr_info? I think this is useful info we want to print out at
default level.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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