linux-kernel - [PATCH v2 2/2] powerpc/pci: Allow to disable filling deprecated pci-OF-bus-map

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Message-Id: <20230128133459.32123-2-pali@kernel.org>
Date:   Sat, 28 Jan 2023 14:34:59 +0100
From:   Pali Rohár <pali@...nel.org>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 2/2] powerpc/pci: Allow to disable filling deprecated pci-OF-bus-map

Creating or filling pci-OF-bus-map property in the device-tree is
deprecated since May 2006 [1]. Allow to disable filling this property by
unsetting config option CONFIG_PPC_PCI_OF_BUS_MAP_FILL for remaining chrp
and powermac code.

Disabling of pci-OF-bus-map property allows to enable new option
CONFIG_PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT also for chrp and powermac.

[1] - https://lore.kernel.org/linuxppc-dev/1148016268.13249.14.camel@localhost.localdomain/

Signed-off-by: Pali Rohár <pali@...nel.org>
---
Changes in v2:
* Provide stripped version of pci_device_from_OF_node() without
  pci_to_OF_bus_map when compiling with CONFIG_PPC_PCI_OF_BUS_MAP_FILL=n
---
 arch/powerpc/Kconfig         | 12 +++++++++++-
 arch/powerpc/kernel/pci_32.c | 30 ++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index fad25aa602c8..3f8499faa88a 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -388,9 +388,19 @@ config PPC_DCR
 	depends on PPC_DCR_NATIVE || PPC_DCR_MMIO
 	default y
 
+config PPC_PCI_OF_BUS_MAP_FILL
+	bool "Fill pci-OF-bus-map property in the device-tree"
+	depends on PPC32
+	depends on PPC_PMAC || PPC_CHRP
+	default y
+	help
+	  This option creates and fills pci-OF-bus-map property in the
+	  device-tree which is deprecated and is needed only for old
+	  platforms.
+
 config PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT
 	depends on PPC32
-	depends on !PPC_PMAC && !PPC_CHRP
+	depends on !PPC_PCI_OF_BUS_MAP_FILL
 	bool "Assign PCI bus numbers from zero individually for each PCI domain"
 	default y
 	help
diff --git a/arch/powerpc/kernel/pci_32.c b/arch/powerpc/kernel/pci_32.c
index 855b59892c5c..82a8981d4c47 100644
--- a/arch/powerpc/kernel/pci_32.c
+++ b/arch/powerpc/kernel/pci_32.c
@@ -64,6 +64,8 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_IBM,	PCI_DEVICE_ID_IBM_CPC710_PCI64,	fixu
 
 #if defined(CONFIG_PPC_PMAC) || defined(CONFIG_PPC_CHRP)
 
+#ifdef CONFIG_PPC_PCI_OF_BUS_MAP_FILL
+
 static u8* pci_to_OF_bus_map;
 static int pci_bus_count;
 
@@ -223,6 +225,32 @@ pci_create_OF_bus_map(void)
 }
 #endif
 
+#else /* CONFIG_PPC_PCI_OF_BUS_MAP_FILL */
+
+/*
+ * Returns the PCI device matching a given OF node without pci_to_OF_bus_map
+ */
+int pci_device_from_OF_node(struct device_node *node, u8 *bus, u8 *devfn)
+{
+	const __be32 *reg;
+	int size;
+
+	/* Check if it might have a chance to be a PCI device */
+	if (!pci_find_hose_for_OF_device(node))
+		return -ENODEV;
+
+	reg = of_get_property(node, "reg", &size);
+	if (!reg || size < 5 * sizeof(u32))
+		return -ENODEV;
+
+	*bus = (be32_to_cpup(&reg[0]) >> 16) & 0xff;
+	*devfn = (be32_to_cpup(&reg[0]) >> 8) & 0xff;
+
+	return 0;
+}
+
+#endif /* CONFIG_PPC_PCI_OF_BUS_MAP_FILL */
+
 #endif /* defined(CONFIG_PPC_PMAC) || defined(CONFIG_PPC_CHRP) */
 
 void pcibios_setup_phb_io_space(struct pci_controller *hose)
@@ -273,6 +301,7 @@ static int __init pcibios_init(void)
 	}
 
 #if defined(CONFIG_PPC_PMAC) || defined(CONFIG_PPC_CHRP)
+#ifdef CONFIG_PPC_PCI_OF_BUS_MAP_FILL
 	pci_bus_count = next_busno;
 
 	/* OpenFirmware based machines need a map of OF bus
@@ -281,6 +310,7 @@ 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 */
-- 
2.20.1