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Commit 4d442331 authored by Olof Johansson's avatar Olof Johansson Committed by Paul Mackerras
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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: default avatarOlof Johansson <olof@lixom.net>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent 68c8404c

arch/powerpc/platforms/pasemi/pci.c

+60 −2
Original line number Diff line number Diff line
@@ -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);

}