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* [PATCH] powerpc/pasemi: Move Nemo i8259 initialization to pci.c
@ 2026-08-01  4:34 chzigotzky
  0 siblings, 0 replies; only message in thread
From: chzigotzky @ 2026-08-01  4:34 UTC (permalink / raw)
  To: chleroy, maddy, mpe, npiggin, linuxppc-dev, linux-kernel
  Cc: rtd2, madskateman, info, hypexed, Darren Stevens,
	Christian Zigotzky

From: Christian Zigotzky A-EON Open Source <info@xenosoft.de>

The Nemo board requires the PCIe ports to be initialized before the
SB600 ISA bridge can be accessed.

Since pas_pci_init() is now called later during boot, the i8259
initialization in pas_init_IRQ() happens too early and accesses
registers that are not yet mapped, preventing the board from booting.

Move the Nemo-specific i8259 initialization to pas_add_bridge(),
after the ISA bridge has been discovered.

Suggested-by: Darren Stevens <darren@stevens-zone.net>
Tested-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Signed-off-by: Christian Zigotzky <chzigotzky@xenosoft.de>
---
 arch/powerpc/platforms/pasemi/pasemi.h |  6 ++++++
 arch/powerpc/platforms/pasemi/pci.c    |  5 +++++
 arch/powerpc/platforms/pasemi/setup.c  | 12 ++++--------
 3 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/platforms/pasemi/pasemi.h b/arch/powerpc/platforms/pasemi/pasemi.h
index 6f6743b8e48d..c37e5c684bb9 100644
--- a/arch/powerpc/platforms/pasemi/pasemi.h
+++ b/arch/powerpc/platforms/pasemi/pasemi.h
@@ -7,6 +7,12 @@ extern void pas_pci_init(void);
 struct pci_dev;
 extern void pas_pci_dma_dev_setup(struct pci_dev *dev);
 
+#ifdef CONFIG_PPC_PASEMI_NEMO
+extern void __init nemo_init_IRQ(void);
+#else
+static inline void __init nemo_init_IRQ(void) { }
+#endif
+
 void __iomem *__init pasemi_pci_getcfgaddr(struct pci_dev *dev, int offset);
 
 extern void __init pasemi_map_registers(void);
diff --git a/arch/powerpc/platforms/pasemi/pci.c b/arch/powerpc/platforms/pasemi/pci.c
index 2df955274652..fb53782da7ec 100644
--- a/arch/powerpc/platforms/pasemi/pci.c
+++ b/arch/powerpc/platforms/pasemi/pci.c
@@ -265,6 +265,11 @@ static int __init pas_add_bridge(struct device_node *dev)
 	 */
 	isa_bridge_find_early(hose);
 
+	/*
+	 * ISA bridge is now active, add the i8259 cascade (if needed)
+	 */
+	nemo_init_IRQ();
+
 	return 0;
 }
 
diff --git a/arch/powerpc/platforms/pasemi/setup.c b/arch/powerpc/platforms/pasemi/setup.c
index d03b41336901..c410e29414ee 100644
--- a/arch/powerpc/platforms/pasemi/setup.c
+++ b/arch/powerpc/platforms/pasemi/setup.c
@@ -214,10 +214,12 @@ static void sb600_8259_cascade(struct irq_desc *desc)
 	chip->irq_eoi(&desc->irq_data);
 }
 
-static void __init nemo_init_IRQ(struct mpic *mpic)
+void __init nemo_init_IRQ(void)
 {
 	struct device_node *np;
 	int gpio_virq;
+	struct mpic *mpic;
+
 	/* Connect the SB600's legacy i8259 controller */
 	np = of_find_node_by_path("/pxp@0,e0000000");
 	i8259_init(np, 0);
@@ -228,14 +230,10 @@ static void __init nemo_init_IRQ(struct mpic *mpic)
 	irq_set_chained_handler(gpio_virq, sb600_8259_cascade);
 	mpic_unmask_irq(irq_get_irq_data(gpio_virq));
 
+	mpic = irq_get_chip_data(gpio_virq);
 	irq_set_default_domain(mpic->irqhost);
 }
 
-#else
-
-static inline void nemo_init_IRQ(struct mpic *mpic)
-{
-}
 #endif
 
 static __init void pas_init_IRQ(void)
@@ -298,8 +296,6 @@ static __init void pas_init_IRQ(void)
 		mpic_unmask_irq(irq_get_irq_data(nmi_virq));
 	}
 
-	nemo_init_IRQ(mpic);
-
 	of_node_put(mpic_node);
 	of_node_put(root);
 }
-- 
2.43.0



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