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Commit 082f55c4 authored by Greg Ungerer's avatar Greg Ungerer
Browse files

m68k: fix ColdFire PCI config reads and writes 



The ColdFire PCI configuration space access functions swap addressing
regions to do their work. Just letting the read/write cycles exit
the CPU core (via the ColdFire "nop" instruction) is not enough to
guarantee that the address region remapping has actually completed.
Insert a read back of the mapping register to be absolutely sure
that the remapping has completed.

This fixes an occasional boot hang during the ColdFire PCI initialization
phase.

Signed-off-by: default avatarGreg Ungerer <gerg@linux-m68k.org>
Reviewed-by: default avatarAngelo Dureghello <angelo@sysam.it>
Tested-by: default avatarAngelo Dureghello <angelo@sysam.it>
parent 48074d26

arch/m68k/coldfire/pci.c

+4 −11
Original line number Diff line number Diff line
@@ -46,13 +46,6 @@ static unsigned char mcf_host_irq[] = { 
	0, 69, 69, 71, 71,

};





static inline void syncio(void)

{

	/* The ColdFire "nop" instruction waits for all bus IO to complete */

	__asm__ __volatile__ ("nop");

}



/*

 * Configuration space access functions. Configuration space access is

 * through the IO mapping window, enabling it via the PCICAR register.
@@ -74,9 +67,9 @@ static int mcf_pci_readconfig(struct pci_bus *bus, unsigned int devfn, 
			return PCIBIOS_SUCCESSFUL;

	}



	syncio();

	addr = mcf_mk_pcicar(bus->number, devfn, where);

	__raw_writel(PCICAR_E | addr, PCICAR);

	__raw_readl(PCICAR);

	addr = iospace + (where & 0x3);



	switch (size) {
@@ -91,8 +84,8 @@ static int mcf_pci_readconfig(struct pci_bus *bus, unsigned int devfn, 
		break;

	}



	syncio();

	__raw_writel(0, PCICAR);

	__raw_readl(PCICAR);

	return PCIBIOS_SUCCESSFUL;

}
@@ -106,9 +99,9 @@ static int mcf_pci_writeconfig(struct pci_bus *bus, unsigned int devfn, 
			return PCIBIOS_SUCCESSFUL;

	}



	syncio();

	addr = mcf_mk_pcicar(bus->number, devfn, where);

	__raw_writel(PCICAR_E | addr, PCICAR);

	__raw_readl(PCICAR);

	addr = iospace + (where & 0x3);



	switch (size) {
@@ -123,8 +116,8 @@ static int mcf_pci_writeconfig(struct pci_bus *bus, unsigned int devfn, 
		break;

	}



	syncio();

	__raw_writel(0, PCICAR);

	__raw_readl(PCICAR);

	return PCIBIOS_SUCCESSFUL;

}