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[POWERPC] pasemi: Add workaround for erratum 5945 

Erratum 5945 causes some of the registers on the PCIe root ports to
not read correctly.  Do a small dance to avoid this: Write an unused
register, read the value and write it back.  Thankfully this is not in
a hot code path.

Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Olof Johansson 2007-09-05 12:08:50 +10:00 committed by Paul Mackerras
parent 68c8404c74
commit 4d442331e5
1 changed files with 60 additions and 2 deletions
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62
arch/powerpc/platforms/pasemi/pci.c
View File

@ -51,6 +51,61 @@ static void volatile __iomem *pa_pxp_cfg_addr(struct pci_controller *hose,
return hose->cfg_data + PA_PXP_CFA(bus, devfn, offset);
}
static inline int is_root_port(int busno, int devfn)
{
return ((busno == 0) && (PCI_FUNC(devfn) < 4) &&
((PCI_SLOT(devfn) == 16) || (PCI_SLOT(devfn) == 17)));
}
static inline int is_5945_reg(int reg)
{
return (((reg >= 0x18) && (reg < 0x34)) ||
((reg >= 0x158) && (reg < 0x178)));
}
static int workaround_5945(struct pci_bus *bus, unsigned int devfn,
int offset, int len, u32 *val)
{
struct pci_controller *hose;
void volatile __iomem *addr, *dummy;
int byte;
u32 tmp;
if (!is_root_port(bus->number, devfn) || !is_5945_reg(offset))
return 0;
hose = pci_bus_to_host(bus);
addr = pa_pxp_cfg_addr(hose, bus->number, devfn, offset & ~0x3);
byte = offset & 0x3;
/* Workaround bug 5945: write 0 to a dummy register before reading,
* and write back what we read. We must read/write the full 32-bit
* contents so we need to shift and mask by hand.
*/
dummy = pa_pxp_cfg_addr(hose, bus->number, devfn, 0x10);
out_le32(dummy, 0);
tmp = in_le32(addr);
out_le32(addr, tmp);
switch (len) {
case 1:
*val = (tmp >> (8*byte)) & 0xff;
break;
case 2:
if (byte == 0)
*val = tmp & 0xffff;
else
*val = (tmp >> 16) & 0xffff;
break;
default:
*val = tmp;
break;
}
return 1;
}
static int pa_pxp_read_config(struct pci_bus *bus, unsigned int devfn,
int offset, int len, u32 *val)
{
@ -64,6 +119,9 @@ static int pa_pxp_read_config(struct pci_bus *bus, unsigned int devfn,
if (!pa_pxp_offset_valid(bus->number, devfn, offset))
return PCIBIOS_BAD_REGISTER_NUMBER;
if (workaround_5945(bus, devfn, offset, len, val))
return PCIBIOS_SUCCESSFUL;
addr = pa_pxp_cfg_addr(hose, bus->number, devfn, offset);
/*
@ -180,7 +238,7 @@ void __iomem *pasemi_pci_getcfgaddr(struct pci_dev *dev, int offset)
{
struct pci_controller *hose;
hose = pci_bus_to_host(bus);
hose = pci_bus_to_host(dev->bus);
return pa_pxp_cfg_addr(hose, hose->number, dev->devfn, int offset)
return (void __iomem *)pa_pxp_cfg_addr(hose, dev->bus->number, dev->devfn, offset);
}