[PATCH v2 2/2] ARM: i.MX8M: add support to handle ROM SError ERR050350

[Marco Felsch <m.felsch@pengutronix.de>]

This ports U-Boot commit:

| commit 2f3c92060dcd6bc9cfd3e2e344a3e1745ca39f09
| Author: Peng Fan <peng.fan@nxp.com>
| Date:   Thu Jul 9 13:39:26 2020 +0800
|
|     imx8m: workaround ROM serror
|
|     ROM SError happens on two cases:
|
|     1. ERR050342, on iMX8MQ HDCP enabled parts ROM writes to GPV1 register, but
|     when ROM patch lock is fused, this write will cause SError.
|
|     2. ERR050350, on iMX8MQ/MM/MN, when the field return fuse is burned, HAB
|     is field return mode, but the last 4K of ROM is still protected and cause
|     SError.
|
|     Since ROM mask SError until ATF unmask it, so then ATF always meets the
|     exception. This patch works around the issue in SPL by enabling SPL
|     Exception vectors table and the SError exception, take the exception
|     to eret immediately to clear the SError.
|
|     Signed-off-by: Ye Li <ye.li@nxp.com>
|     Signed-off-by: Peng Fan <peng.fan@nxp.com>

Other than U-Boot we don't support exceptions in PBL and therefore we
can handle it simpler by installing an dummy exception table to handle
the pending exception. Later on the TF-A overrides the dummy table.

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
---
v2:
- Adapt the Makefile
- Drop the ifdef guard from the errata.h
- Make use of runtime_address() to apply the erratum always during soc
  lowlevel init.

 arch/arm/mach-imx/Makefile                 |  2 ++
 arch/arm/mach-imx/cpu_init.c               | 12 ++++++-
 arch/arm/mach-imx/errata.c                 | 24 +++++++++++++
 arch/arm/mach-imx/imx8m_early_exceptions.S | 42 ++++++++++++++++++++++
 include/mach/imx/errata.h                  |  8 +++++
 5 files changed, 87 insertions(+), 1 deletion(-)
 create mode 100644 arch/arm/mach-imx/errata.c
 create mode 100644 arch/arm/mach-imx/imx8m_early_exceptions.S
 create mode 100644 include/mach/imx/errata.h

diff --git a/arch/arm/mach-imx/Makefile b/arch/arm/mach-imx/Makefile
index cfd066c69de9..22ea48a83330 100644
--- a/arch/arm/mach-imx/Makefile
+++ b/arch/arm/mach-imx/Makefile
@@ -34,6 +34,8 @@ obj-$(CONFIG_BAREBOX_UPDATE_IMX_EXTERNAL_NAND) += imx-bbu-external-nand.o
 pbl-$(CONFIG_USB_GADGET_DRIVER_ARC_PBL) += imx-udc.o
 obj-$(CONFIG_RESET_IMX_SRC) += src.o
 lwl-y += cpu_init.o
+lwl-y += errata.o
+lwl-$(CONFIG_ARCH_IMX8M) += imx8m_early_exceptions.o
 pbl-y += xload-spi.o xload-common.o xload-imx-nand.o xload-gpmi-nand.o
 pbl-y += xload-qspi.o
 obj-pbl-$(CONFIG_ARCH_IMX9) += ele.o
diff --git a/arch/arm/mach-imx/cpu_init.c b/arch/arm/mach-imx/cpu_init.c
index c5a47d9b9154..aebbd3defaec 100644
--- a/arch/arm/mach-imx/cpu_init.c
+++ b/arch/arm/mach-imx/cpu_init.c
@@ -6,6 +6,7 @@
 #include <asm/errata.h>
 #include <linux/types.h>
 #include <linux/bitops.h>
+#include <mach/imx/errata.h>
 #include <mach/imx/generic.h>
 #include <mach/imx/imx7-regs.h>
 #include <mach/imx/imx8mq-regs.h>
@@ -75,17 +76,26 @@ void imx8mm_cpu_lowlevel_init(void)
 	imx8m_ccgr_clock_enable(IMX8M_CCM_CCGR_SCTR);
 
 	imx8m_cpu_lowlevel_init();
+
+	erratum_050350_imx8m();
 }
 
 void imx8mn_cpu_lowlevel_init(void)
 	__alias(imx8mm_cpu_lowlevel_init);
 
 void imx8mp_cpu_lowlevel_init(void)
-	__alias(imx8mm_cpu_lowlevel_init);
+{
+	/* ungate system counter */
+	imx8m_ccgr_clock_enable(IMX8M_CCM_CCGR_SCTR);
+
+	imx8m_cpu_lowlevel_init();
+}
 
 void imx8mq_cpu_lowlevel_init(void)
 {
 	imx8m_cpu_lowlevel_init();
+
+	erratum_050350_imx8m();
 }
 
 #define CCM_AUTHEN_TZ_NS	BIT(9)
diff --git a/arch/arm/mach-imx/errata.c b/arch/arm/mach-imx/errata.c
new file mode 100644
index 000000000000..afab08667879
--- /dev/null
+++ b/arch/arm/mach-imx/errata.c
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include <asm/barebox-arm.h>
+#include <asm/system.h>
+#include <mach/imx/errata.h>
+
+#ifdef CONFIG_CPU_V8
+
+extern char early_imx8m_vectors[];
+
+void erratum_050350_imx8m(void)
+{
+	void *addr;
+
+	if (current_el() != 3)
+		return;
+
+	addr = runtime_address(early_imx8m_vectors);
+
+	asm volatile("msr vbar_el3, %0" : : "r" (addr) : "cc");
+	asm volatile("msr daifclr, #4;isb");
+}
+
+#endif /* CONFIG_CPU_V8 */
diff --git a/arch/arm/mach-imx/imx8m_early_exceptions.S b/arch/arm/mach-imx/imx8m_early_exceptions.S
new file mode 100644
index 000000000000..cd91e1a07b9c
--- /dev/null
+++ b/arch/arm/mach-imx/imx8m_early_exceptions.S
@@ -0,0 +1,42 @@
+/*
+ * (C) Copyright 2013
+ * David Feng <fenghua@phytium.com.cn>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <linux/linkage.h>
+
+#ifdef CONFIG_CPU_V8
+
+/*
+ * Early exception vectors.
+ */
+	.align	11
+	.globl	early_imx8m_vectors
+early_imx8m_vectors:
+	.align	7
+		eret
+
+	.align	7
+		eret
+
+	.align	7
+		eret
+
+	.align	7
+		eret
+
+	.align	7
+		eret
+
+	.align	7
+		eret
+
+	.align	7
+		eret
+
+	.align	7
+		eret
+
+#endif /* CONFIG_CPU_V8 */
diff --git a/include/mach/imx/errata.h b/include/mach/imx/errata.h
new file mode 100644
index 000000000000..c3d28266dca4
--- /dev/null
+++ b/include/mach/imx/errata.h
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef __MACH_IMX_ERRATA_H
+#define __MACH_IMX_ERRATA_H
+
+void erratum_050350_imx8m(void);
+
+#endif /* __MACH_IMX_ERRATA_H */
-- 
2.39.2