From: Olof Johansson <olof@lixom•net>
To: paulus@samba•org
Cc: linuxppc-dev@ozlabs•org
Subject: [POWERPC] pasemi: Add workaround for erratum 5945
Date: Tue, 4 Sep 2007 21:08:50 -0500 [thread overview]
Message-ID: <20070905020850.GC25900@lixom.net> (raw)
In-Reply-To: <20070905020733.GA25900@lixom.net>
commit 3f7a4e905341e46e7b442a9326c3b31229e25209
Author: Olof Johansson <olof@lixom•net>
Date: Mon Sep 3 00:11:49 2007 -0500
[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>
diff --git a/arch/powerpc/platforms/pasemi/pci.c b/arch/powerpc/platforms/pasemi/pci.c
index fcfb3df..b6a0ec4 100644
--- a/arch/powerpc/platforms/pasemi/pci.c
+++ b/arch/powerpc/platforms/pasemi/pci.c
@@ -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);
}
next prev parent reply other threads:[~2007-09-05 3:01 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-05 2:07 Please pull from 'for-2.6.24' branch Olof Johansson
2007-09-05 2:08 ` [POWERPC] pasemi: add pasemi_pci_getcfgaddr() Olof Johansson
2007-09-05 2:08 ` Olof Johansson [this message]
2007-09-05 2:09 ` [POWERPC] pasemi: Export more SPRs to sysfs when CONFIG_DEBUG_KERNEL=y Olof Johansson
2007-09-05 2:09 ` [POWERPC] pasemi: Print more information at machine check Olof Johansson
2007-09-05 2:09 ` [POWERPC] pasemi: Move pasemi_idle_init() to late_initcall() Olof Johansson
2007-09-10 15:44 ` Nathan Lynch
2007-09-10 16:00 ` Olof Johansson
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