The following commit prevents the MPC8548E on the XPedite5200 PrPMC
module from enumerating its PCI/PCI-X bus, though it was previously
able to:
powerpc/fsl-pci: use 'Header Type' to identify PCIE mode
The previous patch prevents any Freescale PCI-X bridge from enumerating
the bus, if it is hardware strapped into Agent mode.
In PCI-X, the Host is responsible for driving the PCI-X initialization
pattern to devices on the bus, so that they know whether to operate in
conventional PCI or PCI-X mode as well as what the bus timing will be.
For a PCI-X PrPMC, the pattern is driven by the mezzanine carrier it is
installed onto. Therefore, PrPMCs are PCI-X Agents, but they may still
enumerate the bus.
This patch depends on firmware to determine if the bridge should
perform enumeration based on factors other than the Host/Agent mode,
such as the state of the VITA 32-defined MONARCH# signal. If firmware
has determined that enumeration should be allowed, then it will set the
bridge's Bus Master bit in the Command register.
Without firmware intervention, the Bus Master bit defaults to 1 in Host
mode and 0 in Agent mode.
Cc: Minghuan Lian <minghuan.l...@freescale.com>
Signed-off-by: Aaron Sierra <asie...@xes-inc.com>
---
arch/powerpc/sysdev/fsl_pci.c | 21 +++++++++++++++++----
1 file changed, 17 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/sysdev/fsl_pci.c b/arch/powerpc/sysdev/fsl_pci.c
index 4bd091a..88d8844 100644
--- a/arch/powerpc/sysdev/fsl_pci.c
+++ b/arch/powerpc/sysdev/fsl_pci.c
@@ -463,7 +463,7 @@ int fsl_add_bridge(struct platform_device *pdev, int
is_primary)
struct pci_controller *hose;
struct resource rsrc;
const int *bus_range;
- u8 hdr_type, progif;
+ u8 hdr_type;
struct device_node *dev;
struct ccsr_pci __iomem *pci;
@@ -520,9 +520,22 @@ int fsl_add_bridge(struct platform_device *pdev, int
is_primary)
goto no_bridge;
} else {
- /* For PCI read PROG to identify controller mode */
- early_read_config_byte(hose, 0, 0, PCI_CLASS_PROG, &progif);
- if ((progif & 1) == 1)
+ u16 master;
+
+ /*
+ * If the controller is PCI-X, then Host mode refers to a
+ * bridge that drives the PCI-X initialization pattern to
+ * indicate bus operating mode/frequency to devices on the bus.
+ * Some hardware (specifically PrPMC modules) are Agents, since
+ * the mezzanine carrier is responsible for driving the
+ * pattern, but they still may perform bus enumeration.
+ *
+ * Allow the bridge to be used for enumeration, if hardware
+ * strapping (Host mode) or firmware (Agent mode) has enabled
+ * bus mastering.
+ */
+ early_read_config_word(hose, 0, 0, PCI_COMMAND, &master);
+ if (!(master & PCI_COMMAND_MASTER))
goto no_bridge;
}
--
1.9.1
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