[PATCH 8/9] bus: brcmstb_gisb: add ARM64 SError support

[opendmb@gmail.com (Doug Berger)]

Asynchronous external aborts (e.g. for buffered writes) trigger SError
aborts on the arm64 architecture.  This commit hooks the SError abort
handling to check for GISB arbitration errors.

Signed-off-by: Doug Berger <opendmb@gmail.com>
---
 drivers/bus/brcmstb_gisb.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/bus/brcmstb_gisb.c b/drivers/bus/brcmstb_gisb.c
index bf26b4017a2c..52b5d96081eb 100644
--- a/drivers/bus/brcmstb_gisb.c
+++ b/drivers/bus/brcmstb_gisb.c
@@ -252,6 +252,28 @@ static int brcmstb_bus_error_handler(unsigned long addr, unsigned int fsr,
 	/* Always report unhandled exception */
 	return 1;
 }
+
+#ifdef CONFIG_ARM64
+static int (*serror_chain)(unsigned long addr, unsigned int esr,
+				struct pt_regs *regs);
+static int do_brahma_b53_serror(unsigned long addr, unsigned int esr,
+				struct pt_regs *regs)
+{
+	struct brcmstb_gisb_arb_device *gdev;
+
+	if (((esr & (3 << 22)) == 0) && ((esr & 3) == 2)) {
+		/* iterate over each GISB arb registered handlers */
+		list_for_each_entry(gdev, &brcmstb_gisb_arb_device_list, next)
+			brcmstb_gisb_arb_decode_addr(gdev, "bus error");
+	}
+
+	if (serror_chain)
+		return serror_chain(addr, esr, regs);
+
+	/* Always report unhandled exception */
+	return 1;
+}
+#endif
 #endif /* CONFIG_ARM || CONFIG_ARM64 */
 
 #ifdef CONFIG_MIPS
@@ -403,6 +425,8 @@ static int __init brcmstb_gisb_arb_probe(struct platform_device *pdev)
 #ifdef CONFIG_ARM64
 	hook_fault_code(16, brcmstb_bus_error_handler, SIGBUS, 0,
 			"synchronous external abort");
+	if (list_is_singular(&brcmstb_gisb_arb_device_list))
+		serror_chain = hook_serror_handler(do_brahma_b53_serror);
 #endif
 #ifdef CONFIG_MIPS
 	board_be_handler = brcmstb_bus_error_handler;
-- 
2.12.0