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