EDAC, mpc85xx: Fix PCIe error capture

According to the reference manual of MPC8572 and T4240, bit 31 of
PEX_ERR_CAP_STAT is W1C (write 1 to clear).

Add the corresponding write to PEX_ERR_CAP_STAT in order to fix the PCIe
error capture.

Tested on a T4240 processor.

Signed-off-by: Tillmann Heidsieck <theidsieck@leenox.de>
Acked-by: Johannes Thumshirn <jthumshirn@suse.de>
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: http://lkml.kernel.org/r/20160815190849.29327-1-theidsieck@leenox.de
Signed-off-by: Borislav Petkov <bp@suse.de>

drivers/edac/mpc85xx_edac.c

@@ -187,14 +187,14 @@ static void mpc85xx_pci_check(struct edac_pci_ctl_info *pci)
 static void mpc85xx_pcie_check(struct edac_pci_ctl_info *pci)
 {
 	struct mpc85xx_pci_pdata *pdata = pci->pvt_info;
-	u32 err_detect;
+	u32 err_detect, err_cap_stat;
 
 	err_detect = in_be32(pdata->pci_vbase + MPC85XX_PCI_ERR_DR);
+	err_cap_stat = in_be32(pdata->pci_vbase + MPC85XX_PCI_GAS_TIMR);
 
 	pr_err("PCIe error(s) detected\n");
 	pr_err("PCIe ERR_DR register: 0x%08x\n", err_detect);
-	pr_err("PCIe ERR_CAP_STAT register: 0x%08x\n",
-			in_be32(pdata->pci_vbase + MPC85XX_PCI_GAS_TIMR));
+	pr_err("PCIe ERR_CAP_STAT register: 0x%08x\n", err_cap_stat);
 	pr_err("PCIe ERR_CAP_R0 register: 0x%08x\n",
 			in_be32(pdata->pci_vbase + MPC85XX_PCIE_ERR_CAP_R0));
 	pr_err("PCIe ERR_CAP_R1 register: 0x%08x\n",
@@ -206,6 +206,9 @@ static void mpc85xx_pcie_check(struct edac_pci_ctl_info *pci)
 
 	/* clear error bits */
 	out_be32(pdata->pci_vbase + MPC85XX_PCI_ERR_DR, err_detect);
+
+	/* reset error capture */
+	out_be32(pdata->pci_vbase + MPC85XX_PCI_GAS_TIMR, err_cap_stat | 0x1);
 }
 
 static int mpc85xx_pcie_find_capability(struct device_node *np)
@@ -344,6 +347,9 @@ static int mpc85xx_pci_err_probe(struct platform_device *op)
 	/* clear error bits */
 	out_be32(pdata->pci_vbase + MPC85XX_PCI_ERR_DR, ~0);
 
+	/* reset error capture */
+	out_be32(pdata->pci_vbase + MPC85XX_PCI_GAS_TIMR, 0x1);
+
 	if (edac_pci_add_device(pci, pdata->edac_idx) > 0) {
 		edac_dbg(3, "failed edac_pci_add_device()\n");
 		goto err;