[PATCH v3] powerpc/pci: Add option for using pci_to_OF_bus_map

[Pali Rohár]

On Monday 06 February 2023 22:39:02 Michael Ellerman wrote:
> From: Pali Rohár <pali at kernel.org>
> 
> The "pci-OF-bus-map" property was declared deprecated in 2006 [1] and to
> the best of everyone's knowledge is not used by anything anymore [2].
> 
> The creation of the property was disabled on powermac (arch/powerpc) in
> 2005 by commit 35499c0195e4 ("powerpc: Merge in 64-bit powermac
> support."). But it is still created by default on CHRP.
> 
> On powermac the actual map (pci_to_OF_bus_map) is still used by default,
> even though the device tree property is not created.
> 
> Add an option to enable/disable use of the pci_to_OF_bus_map, and
> creation of the property (on CHRP).
> 
> Disabling the option allows enabling CONFIG_PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT
> which allows "normal" bus numbering and more than 256 buses, like 64-bit
> and other architectures.
> 
> Mark the new option as default n, the intention is that the option and
> the code will be removed in a future release.
> 
> [1]: https://lore.kernel.org/linuxppc-dev/1148016268.13249.14.camel@localhost.localdomain/
> [2]: https://lore.kernel.org/all/575f239205e8635add81c9f902b7d9db7beb83ea.camel@kernel.crashing.org/
> 
> Signed-off-by: Pali Rohár <pali at kernel.org>
> [mpe: Reword commit & help text, shrink option name, rework to fix build errors]

Thank you for this!

> Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
> ---
>  arch/powerpc/Kconfig                  | 13 ++++++++++++-
>  arch/powerpc/include/asm/pci-bridge.h |  4 +++-
>  arch/powerpc/kernel/pci_32.c          | 17 ++++++++++++-----
>  3 files changed, 27 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index fad25aa602c8..7dcb011cebf2 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -388,9 +388,20 @@ config PPC_DCR
>  	depends on PPC_DCR_NATIVE || PPC_DCR_MMIO
>  	default y
>  
> +config PPC_PCI_OF_BUS_MAP
> +	bool "Use pci_to_OF_bus_map (deprecated)"
> +	depends on PPC32
> +	depends on PPC_PMAC || PPC_CHRP
> +	help
> +	  This option uses pci_to_OF_bus_map to map OF nodes to PCI devices, which
> +	  restricts the system to only having 256 PCI buses. On CHRP it also causes
> +	  the "pci-OF-bus-map" property to be created in the device tree.
> +
> +	  If unsure, say "N".
> +
>  config PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT
>  	depends on PPC32
> -	depends on !PPC_PMAC && !PPC_CHRP
> +	depends on !PPC_PCI_OF_BUS_MAP
>  	bool "Assign PCI bus numbers from zero individually for each PCI domain"
>  	default y
>  	help
> diff --git a/arch/powerpc/include/asm/pci-bridge.h b/arch/powerpc/include/asm/pci-bridge.h
> index e18c95f4e1d4..71c1d26f2400 100644
> --- a/arch/powerpc/include/asm/pci-bridge.h
> +++ b/arch/powerpc/include/asm/pci-bridge.h
> @@ -176,8 +176,10 @@ extern int pci_device_from_OF_node(struct device_node *node,
>  #endif
>  #ifndef CONFIG_PPC64
>  
> -#ifdef CONFIG_PPC_CHRP
> +#ifdef CONFIG_PPC_PCI_OF_BUS_MAP
>  extern void pci_create_OF_bus_map(void);
> +#else
> +static inline void pci_create_OF_bus_map(void) {}
>  #endif
>  
>  #else	/* CONFIG_PPC64 */
> diff --git a/arch/powerpc/kernel/pci_32.c b/arch/powerpc/kernel/pci_32.c
> index 855b59892c5c..ce0c8623e563 100644
> --- a/arch/powerpc/kernel/pci_32.c
> +++ b/arch/powerpc/kernel/pci_32.c
> @@ -62,7 +62,7 @@ fixup_cpc710_pci64(struct pci_dev* dev)
>  }
>  DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_IBM,	PCI_DEVICE_ID_IBM_CPC710_PCI64,	fixup_cpc710_pci64);
>  
> -#if defined(CONFIG_PPC_PMAC) || defined(CONFIG_PPC_CHRP)
> +#ifdef CONFIG_PPC_PCI_OF_BUS_MAP
>  
>  static u8* pci_to_OF_bus_map;
>  static int pci_bus_count;
> @@ -152,6 +152,7 @@ pcibios_make_OF_bus_map(void)
>  	}
>  #endif
>  }
> +#endif // CONFIG_PPC_PCI_OF_BUS_MAP
>  
>  
>  #ifdef CONFIG_PPC_PMAC
> @@ -160,7 +161,9 @@ pcibios_make_OF_bus_map(void)
>   */
>  int pci_device_from_OF_node(struct device_node *node, u8 *bus, u8 *devfn)
>  {
> +#ifdef CONFIG_PPC_PCI_OF_BUS_MAP
>  	struct pci_dev *dev = NULL;
> +#endif
>  	const __be32 *reg;
>  	int size;
>  
> @@ -175,6 +178,9 @@ int pci_device_from_OF_node(struct device_node *node, u8 *bus, u8 *devfn)
>  	*bus = (be32_to_cpup(&reg[0]) >> 16) & 0xff;
>  	*devfn = (be32_to_cpup(&reg[0]) >> 8) & 0xff;
>  
> +#ifndef CONFIG_PPC_PCI_OF_BUS_MAP
> +	return 0;
> +#else
>  	/* Ok, here we need some tweak. If we have already renumbered
>  	 * all busses, we can't rely on the OF bus number any more.
>  	 * the pci_to_OF_bus_map is not enough as several PCI busses
> @@ -192,11 +198,12 @@ int pci_device_from_OF_node(struct device_node *node, u8 *bus, u8 *devfn)
>  		}
>  
>  	return -ENODEV;
> +#endif // CONFIG_PPC_PCI_OF_BUS_MAP
>  }
>  EXPORT_SYMBOL(pci_device_from_OF_node);
>  #endif
>  
> -#ifdef CONFIG_PPC_CHRP
> +#ifdef CONFIG_PPC_PCI_OF_BUS_MAP
>  /* We create the "pci-OF-bus-map" property now so it appears in the
>   * /proc device tree
>   */
> @@ -221,9 +228,7 @@ pci_create_OF_bus_map(void)
>  		of_node_put(dn);
>  	}
>  }
> -#endif
> -
> -#endif /* defined(CONFIG_PPC_PMAC) || defined(CONFIG_PPC_CHRP) */
> +#endif // CONFIG_PPC_PCI_OF_BUS_MAP
>  
>  void pcibios_setup_phb_io_space(struct pci_controller *hose)
>  {
> @@ -273,6 +278,7 @@ static int __init pcibios_init(void)
>  	}
>  
>  #if defined(CONFIG_PPC_PMAC) || defined(CONFIG_PPC_CHRP)
> +#ifdef CONFIG_PPC_PCI_OF_BUS_MAP
>  	pci_bus_count = next_busno;
>  
>  	/* OpenFirmware based machines need a map of OF bus
> @@ -281,6 +287,7 @@ static int __init pcibios_init(void)
>  	 */
>  	if (pci_assign_all_buses)
>  		pcibios_make_OF_bus_map();
> +#endif
>  #endif
>  
>  	/* Call common code to handle resource allocation */
> -- 
> 2.39.1
>