linux-kernel - Re: [PATCH v3 2/5] MIPS: ralink: implement 'pcibios_root_bridge

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Date:   Wed, 12 Jan 2022 10:20:15 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Sergio Paracuellos <sergio.paracuellos@...il.com>
Cc:     linux-pci@...r.kernel.org, tsbogend@...ha.franken.de,
        lorenzo.pieralisi@....com, bhelgaas@...gle.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/5] MIPS: ralink: implement
 'pcibios_root_bridge_prepare()'

On Tue, Dec 07, 2021 at 11:49:21AM +0100, Sergio Paracuellos wrote:
> PCI core code call 'pcibios_root_bridge_prepare()' function inside function
> 'pci_register_host_bridge()'. This point is very good way to properly enter
> into this MIPS ralink specific code to properly setup I/O coherency units
> with PCI memory addresses.
> 
> Signed-off-by: Sergio Paracuellos <sergio.paracuellos@...il.com>

FWIW:

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
>  arch/mips/ralink/mt7621.c | 31 +++++++++++++++++++++++++++++++
>  1 file changed, 31 insertions(+)
> 
> diff --git a/arch/mips/ralink/mt7621.c b/arch/mips/ralink/mt7621.c
> index bd71f5b14238..d6efffd4dd20 100644
> --- a/arch/mips/ralink/mt7621.c
> +++ b/arch/mips/ralink/mt7621.c
> @@ -10,6 +10,8 @@
>  #include <linux/slab.h>
>  #include <linux/sys_soc.h>
>  #include <linux/memblock.h>
> +#include <linux/pci.h>
> +#include <linux/bug.h>
>  
>  #include <asm/bootinfo.h>
>  #include <asm/mipsregs.h>
> @@ -22,6 +24,35 @@
>  
>  static void *detect_magic __initdata = detect_memory_region;
>  
> +int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge)
> +{
> +	struct resource_entry *entry;
> +	resource_size_t mask;
> +
> +	entry = resource_list_first_type(&bridge->windows, IORESOURCE_MEM);
> +	if (!entry) {
> +		pr_err("Cannot get memory resource\n");
> +		return -EINVAL;
> +	}
> +
> +	if (mips_cps_numiocu(0)) {
> +		/*
> +		 * Hardware doesn't accept mask values with 1s after
> +		 * 0s (e.g. 0xffef), so warn if that's happen
> +		 */
> +		mask = ~(entry->res->end - entry->res->start) & CM_GCR_REGn_MASK_ADDRMASK;
> +		WARN_ON(mask && BIT(ffz(~mask)) - 1 != ~mask);
> +
> +		write_gcr_reg1_base(entry->res->start);
> +		write_gcr_reg1_mask(mask | CM_GCR_REGn_MASK_CMTGT_IOCU0);
> +		pr_info("PCI coherence region base: 0x%08llx, mask/settings: 0x%08llx\n",
> +			(unsigned long long)read_gcr_reg1_base(),
> +			(unsigned long long)read_gcr_reg1_mask());
> +	}
> +
> +	return 0;
> +}
> +
>  phys_addr_t mips_cpc_default_phys_base(void)
>  {
>  	panic("Cannot detect cpc address");
> -- 
> 2.33.0
>