The read-only-write-enable bit is set by default and must be cleared
to prevent overwriting read-only registers.  This should be done
immediately after resetting the PCI Express controller.

Reviewed-by: Hamish Martin <hamish.mar...@alliedtelesis.co.nz>

---
Note that this does not implement the whole fix for this erratum,
just what is necessary for our implementation. Since we are using a
fixed RC configuration, no support has been added for EP mode or any
consideration of link-up/down events.

Signed-off-by: Tony O'Brien <tony.obr...@alliedtelesis.co.nz>
---
 arch/powerpc/cpu/mpc85xx/cmd_errata.c     | 3 +++
 arch/powerpc/include/asm/config_mpc85xx.h | 1 +
 arch/powerpc/include/asm/fsl_pci.h        | 4 +++-
 drivers/pci/fsl_pci_init.c                | 7 +++++++
 4 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/cpu/mpc85xx/cmd_errata.c 
b/arch/powerpc/cpu/mpc85xx/cmd_errata.c
index 402a1ff..aabb56b 100644
--- a/arch/powerpc/cpu/mpc85xx/cmd_errata.c
+++ b/arch/powerpc/cpu/mpc85xx/cmd_errata.c
@@ -330,6 +330,9 @@ static int do_errata(cmd_tbl_t *cmdtp, int flag, int argc, 
char * const argv[])
 #ifdef CONFIG_SYS_FSL_ERRATUM_A009663
        puts("Work-around for Erratum A009663 enabled\n");
 #endif
+#ifdef CONFIG_SYS_FSL_ERRATUM_A007815
+       puts("Work-around for Erratum A007815 enabled\n");
+#endif
 
        return 0;
 }
diff --git a/arch/powerpc/include/asm/config_mpc85xx.h 
b/arch/powerpc/include/asm/config_mpc85xx.h
index c92bc1e..c298e44 100644
--- a/arch/powerpc/include/asm/config_mpc85xx.h
+++ b/arch/powerpc/include/asm/config_mpc85xx.h
@@ -785,6 +785,7 @@ defined(CONFIG_PPC_T1014) || defined(CONFIG_PPC_T1013)
 #define CONFIG_SYS_FSL_ERRATUM_A006593
 #define CONFIG_SYS_FSL_ERRATUM_A007186
 #define CONFIG_SYS_FSL_ERRATUM_A006379
+#define CONFIG_SYS_FSL_ERRATUM_A007815
 #define ESDHCI_QUIRK_BROKEN_TIMEOUT_VALUE
 #define CONFIG_SYS_FSL_SFP_VER_3_0
 
diff --git a/arch/powerpc/include/asm/fsl_pci.h 
b/arch/powerpc/include/asm/fsl_pci.h
index 8bee8ca..cad341e 100644
--- a/arch/powerpc/include/asm/fsl_pci.h
+++ b/arch/powerpc/include/asm/fsl_pci.h
@@ -79,7 +79,9 @@ typedef struct ccsr_pci {
        u32     pme_msg_dis;    /* 0x024 - PCIE PME & message disable register 
*/
        u32     pme_msg_int_en; /* 0x028 - PCIE PME & message interrupt enable 
register */
        u32     pm_command;     /* 0x02c - PCIE PM Command register */
-       char    res4[3016];     /*     (- #xbf8  #x30)3016 */
+       char    res3[2188];     /*     (0x8bc - 0x30 = 2188) */
+       u32     dbi_ro_wr_en;   /* 0x8bc - DBI read only write enable reg */
+       char    res4[824];      /*     (0xbf8 - 0x8c0 = 824) */
        u32     block_rev1;     /* 0xbf8 - PCIE Block Revision register 1 */
        u32     block_rev2;     /* 0xbfc - PCIE Block Revision register 2 */
 
diff --git a/drivers/pci/fsl_pci_init.c b/drivers/pci/fsl_pci_init.c
index 52792dc..af20cf0 100644
--- a/drivers/pci/fsl_pci_init.c
+++ b/drivers/pci/fsl_pci_init.c
@@ -543,6 +543,13 @@ void fsl_pci_init(struct pci_controller *hose, struct 
fsl_pci_info *pci_info)
                pciauto_prescan_setup_bridge(hose, dev, hose->current_busno);
        }
 
+#ifdef CONFIG_SYS_FSL_ERRATUM_A007815
+       /* The Read-Only Write Enable bit defaults to 1 instead of 0.
+        * Set to 0 to protect the read-only registers.
+        */
+       clrbits_be32(&pci->dbi_ro_wr_en, 0x01);
+#endif
+
        /* Use generic setup_device to initialize standard pci regs,
         * but do not allocate any windows since any BAR found (such
         * as PCSRBAR) is not in this cpu's memory space.
-- 
2.10.2

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