MIPS: BCM47XX: Enable 74K Core ExternalSync for PCIe erratum

The erratum and workaround are described by BCM5300X-ES300-RDS.pdf as
below.

  R10: PCIe Transactions Periodically Fail

    Description: The BCM5300X PCIe does not maintain transaction ordering.
                 This may cause PCIe transaction failure.
    Fix Comment: Add a dummy PCIe configuration read after a PCIe
                 configuration write to ensure PCIe configuration access
                 ordering. Set ES bit of CP0 configu7 register to enable
                 sync function so that the sync instruction is functional.
    Resolution:  hndpci.c: extpci_write_config()
                 hndmips.c: si_mips_init()
                 mipsinc.h CONF7_ES

This is fixed by the CFE MIPS bcmsi chipset driver also for BCM47XX.
Also the dummy PCIe configuration read is already implemented in the
Linux BCMA driver.

Enable ExternalSync in Config7 when CONFIG_BCMA_DRIVER_PCI_HOSTMODE=y
too so that the sync instruction is externalised.

Signed-off-by: Tokunori Ikegami <[email protected]>
Reviewed-by: Paul Burton <[email protected]>
Acked-by: Hauke Mehrtens <[email protected]>
Cc: Chris Packham <[email protected]>
Cc: Rafał Miłecki <[email protected]>
Cc: [email protected]
Cc: [email protected]
Patchwork: https://patchwork.linux-mips.org/patch/19461/
Signed-off-by: James Hogan <[email protected]>

diff --git a/arch/mips/bcm47xx/setup.c b/arch/mips/bcm47xx/setup.c
index 6054d49e608eec038e1bbd49599bc783270aa09a..8c9cbf13d32a0a471bc6f2653bbb3c459b1b2c2c 100644 (file)
--- a/arch/mips/bcm47xx/setup.c
+++ b/arch/mips/bcm47xx/setup.c
@@ -212,6 +212,12 @@ static int __init bcm47xx_cpu_fixes(void)
                 */
                if (bcm47xx_bus.bcma.bus.chipinfo.id == BCMA_CHIP_ID_BCM4706)
                        cpu_wait = NULL;
+
+               /*
+                * BCM47XX Erratum "R10: PCIe Transactions Periodically Fail"
+                * Enable ExternalSync for sync instruction to take effect
+                */
+               set_c0_config7(MIPS_CONF7_ES);
                break;
 #endif
        }

diff --git a/arch/mips/include/asm/mipsregs.h b/arch/mips/include/asm/mipsregs.h
index ae461d91cd1faef06dc39399e7910eb28471d930..0bc270806ec5a68dbb030d6f47d26e46485c0ea0 100644 (file)
--- a/arch/mips/include/asm/mipsregs.h
+++ b/arch/mips/include/asm/mipsregs.h
@@ -681,6 +681,8 @@
 #define MIPS_CONF7_WII         (_ULCAST_(1) << 31)
 
 #define MIPS_CONF7_RPS         (_ULCAST_(1) << 2)
+/* ExternalSync */
+#define MIPS_CONF7_ES          (_ULCAST_(1) << 8)
 
 #define MIPS_CONF7_IAR         (_ULCAST_(1) << 10)
 #define MIPS_CONF7_AR          (_ULCAST_(1) << 16)
@@ -2765,6 +2767,7 @@ __BUILD_SET_C0(status)
 __BUILD_SET_C0(cause)
 __BUILD_SET_C0(config)
 __BUILD_SET_C0(config5)
+__BUILD_SET_C0(config7)
 __BUILD_SET_C0(intcontrol)
 __BUILD_SET_C0(intctl)
 __BUILD_SET_C0(srsmap)