ARM: 9480/1: entry: expand comment in __switch_tografted

As per discussion between the developers in the mail thread
linked, expand the comment in __switch_to so that readers
of the code understand what is going on.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Linus Walleij <linusw@kernel.org>>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

1 files changed, 77 insertions, 0 deletions

diff --git a/drivers/firmware/qcom/Kconfig b/drivers/firmware/qcom/Kconfig
new file mode 100644
index 000000000..b477d54b4
--- /dev/null
+++ b/drivers/firmware/qcom/Kconfig
@@ -0,0 +1,77 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# For a description of the syntax of this configuration file,
+# see Documentation/kbuild/kconfig-language.rst.
+#
+
+menu "Qualcomm firmware drivers"
+
+config QCOM_SCM
+	select QCOM_TZMEM
+	tristate
+
+config QCOM_TZMEM
+	tristate
+	select GENERIC_ALLOCATOR
+
+choice
+	prompt "TrustZone interface memory allocator mode"
+	depends on QCOM_TZMEM
+	default QCOM_TZMEM_MODE_GENERIC
+	help
+	  Selects the mode of the memory allocator providing memory buffers of
+	  suitable format for sharing with the TrustZone. If in doubt, select
+	  'Generic'.
+
+config QCOM_TZMEM_MODE_GENERIC
+	bool "Generic"
+	help
+	  Use the generic allocator mode. The memory is page-aligned, non-cachable
+	  and physically contiguous.
+
+config QCOM_TZMEM_MODE_SHMBRIDGE
+	bool "SHM Bridge"
+	help
+	  Use Qualcomm Shared Memory Bridge. The memory has the same alignment as
+	  in the 'Generic' allocator but is also explicitly marked as an SHM Bridge
+	  buffer.
+
+	  With this selected, all buffers passed to the TrustZone must be allocated
+	  using the TZMem allocator or else the TrustZone will refuse to use them.
+
+endchoice
+
+config QCOM_QSEECOM
+	bool "Qualcomm QSEECOM interface driver"
+	depends on QCOM_SCM=y
+	select AUXILIARY_BUS
+	help
+	  Various Qualcomm SoCs have a Secure Execution Environment (SEE) running
+	  in the Trust Zone. This module provides an interface to that via the
+	  QSEECOM mechanism, using SCM calls.
+
+	  The QSEECOM interface allows, among other things, access to applications
+	  running in the SEE. An example of such an application is 'uefisecapp',
+	  which is required to access UEFI variables on certain systems. If
+	  selected, the interface will also attempt to detect and register client
+	  devices for supported applications.
+
+	  Select Y here to enable the QSEECOM interface driver.
+
+config QCOM_QSEECOM_UEFISECAPP
+	bool "Qualcomm SEE UEFI Secure App client driver"
+	depends on QCOM_QSEECOM
+	depends on EFI
+	help
+	  Various Qualcomm SoCs do not allow direct access to EFI variables.
+	  Instead, these need to be accessed via the UEFI Secure Application
+	  (uefisecapp), residing in the Secure Execution Environment (SEE).
+
+	  This module provides a client driver for uefisecapp, installing efivar
+	  operations to allow the kernel accessing EFI variables, and via that also
+	  provide user-space with access to EFI variables via efivarfs.
+
+	  Select Y here to provide access to EFI variables on the aforementioned
+	  platforms.
+
+endmenu