[U-Boot] [PATCH] mpc85xx: pci: Implement workaround for Erratum A007815

[Tony O'Brien]

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.martin at 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.obrien at 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