[U-Boot] [PATCH 1/2] spl: atf: add SPL_ATF_NO_PLATFORM_PARAM option

[Philipp Tomsich]

While we expect to call a pointer to a valid FDT (or NULL) as the
platform parameter to an ATF, some ATF versions are not U-Boot aware
and have an insufficiently robust (or an overzealour) parameter
validation: either way, this may cause a hard-stop with uncooperative
ATF versions.

This change adds the option to suppress passing a platform parameter
and will always pass NULL.

Debug output from ATF w/ this option disabled (i.e. default):
      INFO:    plat_param_from_bl2: 0x291450
Debug output from ATF w/ this option enabled:
      INFO:    plat_param_from_bl2: 0

Signed-off-by: Philipp Tomsich <philipp.tomsich at theobroma-systems.com>
Tested-by: Philipp Tomsich <philipp.tomsich at theobroma-systems.com>
---

 common/spl/Kconfig   | 18 ++++++++++++++++--
 common/spl/spl_atf.c | 12 +++++++++++-
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/common/spl/Kconfig b/common/spl/Kconfig
index aef0034..9d35f41 100644
--- a/common/spl/Kconfig
+++ b/common/spl/Kconfig
@@ -721,10 +721,24 @@ config SPL_ATF
 	bool "Support ARM Trusted Firmware"
 	depends on ARM64
 	help
-	  ATF(ARM Trusted Firmware) is a component for ARM arch64 which
-	  is loaded by SPL(which is considered as BL2 in ATF terminology).
+	  ATF(ARM Trusted Firmware) is a component for ARM AArch64 which
+	  is loaded by SPL (which is considered as BL2 in ATF terminology).
 	  More detail at: https://github.com/ARM-software/arm-trusted-firmware
 
+config SPL_ATF_NO_PLATFORM_PARAM
+        bool "Pass no platform parameter"
+	depends on SPL_ATF
+	help
+	  While we expect to call a pointer to a valid FDT (or NULL)
+	  as the platform parameter to an ATF, some ATF versions are
+	  not U-Boot aware and have an insufficiently robust parameter
+	  validation to gracefully reject a FDT being passed.
+
+	  If this option is enabled, the spl_atf os-type handler will
+	  always pass NULL for the platform parameter.
+
+	  If your ATF is affected, say Y.
+
 config TPL
 	bool
 	depends on SUPPORT_TPL
diff --git a/common/spl/spl_atf.c b/common/spl/spl_atf.c
index 63557c0..a942de9 100644
--- a/common/spl/spl_atf.c
+++ b/common/spl/spl_atf.c
@@ -144,6 +144,7 @@ void spl_invoke_atf(struct spl_image_info *spl_image)
 {
 	uintptr_t  bl33_entry = CONFIG_SYS_TEXT_BASE;
 	void *blob = spl_image->fdt_addr;
+	uintptr_t platform_param = (uintptr_t)blob;
 	int node;
 
 	/*
@@ -158,8 +159,17 @@ void spl_invoke_atf(struct spl_image_info *spl_image)
 		bl33_entry = spl_fit_images_get_entry(blob, node);
 
 	/*
+	 * If ATF_NO_PLATFORM_PARAM is set, we override the platform
+	 * parameter and always pass 0.  This is a workaround for
+	 * older ATF versions that have insufficiently robust (or
+	 * overzealous) argument validation.
+	 */
+	if (CONFIG_IS_ENABLED(ATF_NO_PLATFORM_PARAM))
+		platform_param = 0;
+
+	/*
 	 * We don't provide a BL3-2 entry yet, but this will be possible
 	 * using similar logic.
 	 */
-	bl31_entry(spl_image->entry_point, bl33_entry, (uintptr_t)blob);
+	bl31_entry(spl_image->entry_point, bl33_entry, platform_param);
 }
-- 
2.1.4