[PATCH 4/5] ARM: i.MX8M: support saving BootROM event log before clobbering OCRAM

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

The ROM event log[1] is a data structure populated by the i.MX BootROM
on i.MX6 and later. It's found by dereferencing a 32-bit address at a
fixed location within the BootROM. If valid, this address will point
into the On-Chip SRAM. On the i.MX8M, we load the ARM trusted firmware
into the On-Chip SRAM and may end up overwriting the BootROM event log,
before the user has a chance to parse it. Thus save the BootROM log into
the newly defined i.MX scratch space for later usage.

[1]: NXP AN12853 "i.MX ROMs Log Events" Rev. 0 -  May 2020

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 arch/arm/mach-imx/Kconfig                   |  3 +++
 arch/arm/mach-imx/atf.c                     |  3 +++
 arch/arm/mach-imx/include/mach/imx8m-regs.h |  8 +++++++
 arch/arm/mach-imx/include/mach/romapi.h     | 11 +++++++++
 arch/arm/mach-imx/romapi.c                  | 26 +++++++++++++++++++++
 5 files changed, 51 insertions(+)

diff --git a/arch/arm/mach-imx/Kconfig b/arch/arm/mach-imx/Kconfig
index da71480887ad..e99cadb1f53a 100644
--- a/arch/arm/mach-imx/Kconfig
+++ b/arch/arm/mach-imx/Kconfig
@@ -932,6 +932,9 @@ config IMX_IIM_FUSE_BLOW
 	  enable it:
 	    imx_iim0.permanent_write_enable=1
 
+config IMX_SAVE_BOOTROM_LOG
+	bool
+
 config HAB
 	bool
 
diff --git a/arch/arm/mach-imx/atf.c b/arch/arm/mach-imx/atf.c
index 67462bc36189..9907e5f2ba97 100644
--- a/arch/arm/mach-imx/atf.c
+++ b/arch/arm/mach-imx/atf.c
@@ -125,6 +125,7 @@ void imx8mm_load_bl33(void *bl33)
 
 __noreturn void imx8mm_load_and_start_image_via_tfa(void)
 {
+	imx8mm_save_bootrom_log();
 	imx8mm_load_bl33((void *)MX8M_ATF_BL33_BASE_ADDR);
 	imx8mm_load_and_start_tfa(imx8mm_bl31_bin);
 }
@@ -161,6 +162,7 @@ void imx8mp_load_bl33(void *bl33)
 
 void imx8mp_load_and_start_image_via_tfa(void)
 {
+	imx8mp_save_bootrom_log();
 	imx8mp_load_bl33((void *)MX8M_ATF_BL33_BASE_ADDR);
 	imx8mp_load_and_start_tfa(imx8mp_bl31_bin);
 }
@@ -197,6 +199,7 @@ void imx8mn_load_bl33(void *bl33)
 
 void imx8mn_load_and_start_image_via_tfa(void)
 {
+	imx8mn_save_bootrom_log();
 	imx8mn_load_bl33((void *)MX8M_ATF_BL33_BASE_ADDR);
 	imx8mn_load_and_start_tfa(imx8mn_bl31_bin);
 }
diff --git a/arch/arm/mach-imx/include/mach/imx8m-regs.h b/arch/arm/mach-imx/include/mach/imx8m-regs.h
index a5017faf830e..794e1bdd88a4 100644
--- a/arch/arm/mach-imx/include/mach/imx8m-regs.h
+++ b/arch/arm/mach-imx/include/mach/imx8m-regs.h
@@ -3,6 +3,14 @@
 #ifndef __MACH_IMX8M_REGS_H
 #define __MACH_IMX8M_REGS_H
 
+/*
+ * Actual addressable OCRAM size may differ from SoC to SoC, but all of
+ * i.MX8MQ/M/N/P have this region of MMIO address space set aside for
+ * OCRAM only.
+ */
+#define	MX8M_OCRAM_BASE_ADDR		0x00900000
+#define	MX8M_OCRAM_MAX_SIZE		0x00200000
+
 #define MX8M_GPIO1_BASE_ADDR		0X30200000
 #define MX8M_GPIO2_BASE_ADDR		0x30210000
 #define MX8M_GPIO3_BASE_ADDR		0x30220000
diff --git a/arch/arm/mach-imx/include/mach/romapi.h b/arch/arm/mach-imx/include/mach/romapi.h
index 8022fc411e9d..d22ba7259dd0 100644
--- a/arch/arm/mach-imx/include/mach/romapi.h
+++ b/arch/arm/mach-imx/include/mach/romapi.h
@@ -1,6 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
 #ifndef __MACH_IMX_ROMAPI_H
 #define __MACH_IMX_ROMAPI_H
 
+#include <mach/xload.h>
+
 struct rom_api {
 	u16 ver;
 	u16 tag;
@@ -34,4 +37,12 @@ enum boot_dev_type_e {
 int imx8mp_bootrom_load_image(void);
 int imx8mn_bootrom_load_image(void);
 
+/* only call after DRAM has been configured */
+void imx8m_save_bootrom_log(void *dst);
+
+#define imx8mq_save_bootrom_log() imx8m_save_bootrom_log(imx8mq_scratch_space())
+#define imx8mm_save_bootrom_log() imx8m_save_bootrom_log(imx8mm_scratch_space())
+#define imx8mn_save_bootrom_log() imx8m_save_bootrom_log(imx8mn_scratch_space())
+#define imx8mp_save_bootrom_log() imx8m_save_bootrom_log(imx8mp_scratch_space())
+
 #endif /* __MACH_IMX_ROMAPI_H */
diff --git a/arch/arm/mach-imx/romapi.c b/arch/arm/mach-imx/romapi.c
index 5d00d71154d7..48512a8d045e 100644
--- a/arch/arm/mach-imx/romapi.c
+++ b/arch/arm/mach-imx/romapi.c
@@ -1,7 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#define pr_fmt(fmt) "romapi: " fmt
+
 #include <common.h>
 #include <asm/sections.h>
 #include <mach/romapi.h>
 #include <mach/atf.h>
+#include <mach/imx8m-regs.h>
 
 static int imx8m_bootrom_load(struct rom_api *rom_api, void *adr, size_t size)
 {
@@ -42,3 +47,24 @@ int imx8mn_bootrom_load_image(void)
 {
 	return imx8mp_bootrom_load_image();
 }
+
+void imx8m_save_bootrom_log(void *dest)
+{
+	ulong rom_log_addr;
+
+	if (!IS_ENABLED(CONFIG_IMX_SAVE_BOOTROM_LOG)) {
+		pr_debug("skipping bootrom log saving\n");
+		return;
+	}
+
+	rom_log_addr = *(u32 *)0x9e0;
+
+	if (rom_log_addr < MX8M_OCRAM_BASE_ADDR ||
+	    rom_log_addr >= MX8M_OCRAM_BASE_ADDR + MX8M_OCRAM_MAX_SIZE ||
+	    rom_log_addr & 0x3) {
+		pr_warn("No BootROM log found at address 0x%08lx\n", rom_log_addr);
+		return;
+	}
+
+	memcpy(dest, (u32 *)rom_log_addr, 128 * sizeof(u32));
+}
-- 
2.30.2