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

commit 2a027b47dba6b77ab8c8e47b589ae9bbc5ac6175 upstream.

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 <ikegami@allied-telesis.co.jp>
Reviewed-by: Paul Burton <paul.burton@mips.com>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
Cc: Chris Packham <chris.packham@alliedtelesis.co.nz>
Cc: Rafał Miłecki <zajec5@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/19461/
Signed-off-by: James Hogan <jhogan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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 df78b2ca70ebd8c6b57348f9e62f304394f4f3d0..22a6782f84f5010f8f9e348e557c8bd2cca19d1e 100644 (file)
--- a/arch/mips/include/asm/mipsregs.h
+++ b/arch/mips/include/asm/mipsregs.h
@@ -663,6 +663,8 @@
 #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)
@@ -2641,6 +2643,7 @@ __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)