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m68k: fix ColdFire PCI config reads and writes

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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: Greg Ungerer <gerg@linux-m68k.org>
Reviewed-by: Angelo Dureghello <angelo@sysam.it>
Tested-by: Angelo Dureghello <angelo@sysam.it>
This commit is contained in:
Greg Ungerer 2018-04-11 13:39:44 +10:00
parent 48074d2615
commit 082f55c459
1 changed files with 4 additions and 11 deletions
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15
arch/m68k/coldfire/pci.c
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@ -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;
}