[U-Boot] [PATCH v5 18/19] env, efi_loader: define env context for UEFI variables

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

We will use two environment contexts for implementing UEFI variables,
one (ctx_efi) for non-volatile variables and the other for volatile
variables. The latter doesn't have a backing storage.

Those two contexts are currently used only in efi_variable.c and
can be moved into there if desired. But I let it under env/ for
future use elsewhere.

In this commit, FAT file system and flash device are only supported
devices for backing storages, but extending to other devices will be
quite straightforward.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
---
 env/Kconfig       |   1 +
 env/Kconfig.efi   | 152 ++++++++++++++++++++++++++++++++++++++++++++++
 env/Makefile      |   1 +
 env/env_ctx_efi.c | 131 +++++++++++++++++++++++++++++++++++++++
 include/env.h     |   3 +
 5 files changed, 288 insertions(+)
 create mode 100644 env/Kconfig.efi
 create mode 100644 env/env_ctx_efi.c

diff --git a/env/Kconfig b/env/Kconfig
index ae96cf75bbaa..0cd3caa67376 100644
--- a/env/Kconfig
+++ b/env/Kconfig
@@ -47,5 +47,6 @@ config ENV_DRV_UBI
 	bool
 
 source "env/Kconfig.uboot"
+source "env/Kconfig.efi"
 
 endmenu
diff --git a/env/Kconfig.efi b/env/Kconfig.efi
new file mode 100644
index 000000000000..cd4e78989df6
--- /dev/null
+++ b/env/Kconfig.efi
@@ -0,0 +1,152 @@
+if EFI_LOADER
+
+menu "Configure UEFI context"
+
+config ENV_EFI_IS_NOWHERE
+	bool
+	default y if !ENV_EFI_IS_INFLASH && !ENV_EFI_IS_IN_FAT
+
+config ENV_EFI_IS_IN_FAT
+	bool "EFI Environment is in a FAT filesystem"
+	select ENV_DRV_FAT
+	help
+	  Define this if you want to use the FAT file system for
+	  the environment.
+
+config ENV_EFI_IS_IN_FLASH
+	bool "EFI Environment in flash memory"
+	select ENV_DRV_FLASH
+	help
+	  Define this if you have a flash device which you want to use
+	  for the environment.
+
+	  a) The environment occupies one whole flash sector, which is
+	   "embedded" in the text segment with the U-Boot code. This
+	   happens usually with "bottom boot sector" or "top boot
+	   sector" type flash chips, which have several smaller
+	   sectors at the start or the end. For instance, such a
+	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
+	   such a case you would place the environment in one of the
+	   4 kB sectors - with U-Boot code before and after it. With
+	   "top boot sector" type flash chips, you would put the
+	   environment in one of the last sectors, leaving a gap
+	   between U-Boot and the environment.
+
+	  CONFIG_ENV_EFI_OFFSET:
+
+	   Offset of environment data (variable area) to the
+	   beginning of flash memory; for instance, with bottom boot
+	   type flash chips the second sector can be used: the offset
+	   for this sector is given here.
+
+	   CONFIG_ENV_EFI_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
+
+	  CONFIG_ENV_EFI_ADDR:
+
+	   This is just another way to specify the start address of
+	   the flash sector containing the environment (instead of
+	   CONFIG_ENV_OFFSET).
+
+	  CONFIG_ENV_EFI_SECT_SIZE:
+
+	   Size of the sector containing the environment.
+
+
+	  b) Sometimes flash chips have few, equal sized, BIG sectors.
+	   In such a case you don't want to spend a whole sector for
+	   the environment.
+
+	  CONFIG_ENV_EFI_SIZE:
+
+	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
+	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
+	   of this flash sector for the environment. This saves
+	   memory for the RAM copy of the environment.
+
+	   It may also save flash memory if you decide to use this
+	   when your environment is "embedded" within U-Boot code,
+	   since then the remainder of the flash sector could be used
+	   for U-Boot code. It should be pointed out that this is
+	   STRONGLY DISCOURAGED from a robustness point of view:
+	   updating the environment in flash makes it always
+	   necessary to erase the WHOLE sector. If something goes
+	   wrong before the contents has been restored from a copy in
+	   RAM, your target system will be dead.
+
+	  CONFIG_ENV_EFI_ADDR_REDUND
+	  CONFIG_ENV_EFI_SIZE_REDUND
+
+	   These settings describe a second storage area used to hold
+	   a redundant copy of the environment data, so that there is
+	   a valid backup copy in case there is a power failure during
+	   a "saveenv" operation.
+
+	  BE CAREFUL! Any changes to the flash layout, and some changes to the
+	  source code will make it necessary to adapt <board>/u-boot.lds*
+	  accordingly!
+
+config ENV_EFI_FAT_INTERFACE
+	string "Name of the block device for the environment"
+	depends on ENV_EFI_IS_IN_FAT
+	help
+	  Define this to a string that is the name of the block device.
+
+config ENV_EFI_FAT_DEVICE_AND_PART
+	string "Device and partition for where to store the environment in FAT"
+	depends on ENV_EFI_IS_IN_FAT
+	help
+	  Define this to a string to specify the partition of the device.
+	  It can be as following:
+
+	    "D:P", "D:0", "D", "D:" or "D:auto" (D, P are integers. And P >= 1)
+	       - "D:P": device D partition P. Error occurs if device D has no
+	                partition table.
+	       - "D:0": device D.
+	       - "D" or "D:": device D partition 1 if device D has partition
+	                      table, or the whole device D if has no partition
+	                      table.
+	       - "D:auto": first partition in device D with bootable flag set.
+	                   If none, first valid partition in device D. If no
+	                   partition table then means device D.
+
+config ENV_EFI_FAT_FILE
+	string "Name of the FAT file to use for the environment"
+	depends on ENV_EFI_IS_IN_FAT
+	default "uboot_efi.env"
+	help
+	  It's a string of the FAT file name. This file use to store the
+	  environment.
+
+config ENV_EFI_ADDR
+	hex "EFI Environment Address"
+	help
+	  Start address of the device (or partition)
+
+config ENV_EFI_OFFSET
+	hex "EFI Environment Offset"
+	help
+	  Offset from the start of the device (or partition)
+
+config ENV_EFI_SIZE
+	hex "EFI Environment Size"
+	help
+	  Size of the environment storage area
+
+config ENV_EFI_SECT_SIZE
+	hex "EFI Environment Sector-Size"
+	help
+	  Size of the sector containing the environment.
+
+config ENV_EFI_ADDR_REDUND
+	hex "EFI Environment Address for second area"
+	help
+	  Start address of the device (or partition)
+
+config ENV_EFI_SIZE_REDUND
+	hex "EFI Environment Size for second area"
+	help
+	  Size of the environment second storage area
+
+endmenu
+
+endif
diff --git a/env/Makefile b/env/Makefile
index 0168eb47f00d..b6690c73b17f 100644
--- a/env/Makefile
+++ b/env/Makefile
@@ -4,6 +4,7 @@
 # Wolfgang Denk, DENX Software Engineering, wd at denx.de.
 
 obj-y += common.o env.o env_ctx_uboot.o
+obj-$(CONFIG_EFI_LOADER) += env_ctx_efi.o
 
 ifndef CONFIG_SPL_BUILD
 obj-y += attr.o
diff --git a/env/env_ctx_efi.c b/env/env_ctx_efi.c
new file mode 100644
index 000000000000..9b5b2f392179
--- /dev/null
+++ b/env/env_ctx_efi.c
@@ -0,0 +1,131 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2019 Linaro Limited
+ *		Author: AKASHI Takahiro
+ */
+
+#include <common.h>
+#include <env_flags.h>
+#include <env_internal.h>
+#include <search.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct hsearch_data efi_htab = {
+#if CONFIG_IS_ENABLED(ENV_SUPPORT)
+	/* defined in flags.c, only compile with ENV_SUPPORT */
+	.change_ok = env_flags_validate,
+#endif
+};
+
+struct hsearch_data efi_volatile_htab = {
+#if CONFIG_IS_ENABLED(ENV_SUPPORT)
+	/* defined in flags.c, only compile with ENV_SUPPORT */
+	.change_ok = env_flags_validate,
+#endif
+};
+
+static int env_drv_init_efi(struct env_context *ctx, enum env_location loc)
+{
+	__maybe_unused int ret;
+
+	switch (loc) {
+#ifdef CONFIG_ENV_EFI_IS_IN_FLASH
+	case ENVL_FLASH: {
+		env_t *env_ptr;
+		env_t *flash_addr;
+		ulong end_addr;
+		env_t *flash_addr_new;
+		ulong end_addr_new;
+
+#if defined(CONFIG_ENV_EFI_ADDR_REDUND) && defined(CMD_SAVEENV) || \
+	!defined(CONFIG_ENV_EFI_ADDR_REDUND) && defined(INITENV)
+#ifdef ENV_IS_EMBEDDED
+		/* FIXME: not allowed */
+		env_ptr = NULL;
+#else /* ! ENV_IS_EMBEDDED */
+
+		env_ptr = (env_t *)CONFIG_ENV_EFI_ADDR;
+#endif /* ENV_IS_EMBEDDED */
+#else
+		env_ptr = NULL;
+#endif
+		flash_addr = (env_t *)CONFIG_ENV_EFI_ADDR;
+
+/* CONFIG_ENV_EFI_ADDR is supposed to be on sector boundary */
+		end_addr = CONFIG_ENV_EFI_ADDR + CONFIG_ENV_EFI_SECT_SIZE - 1;
+
+#ifdef CONFIG_ENV_EFI_ADDR_REDUND
+		flash_addr_new = (env_t *)CONFIG_ENV_EFI_ADDR_REDUND;
+/* CONFIG_ENV_EFI_ADDR_REDUND is supposed to be on sector boundary */
+		end_addr_new = CONFIG_ENV_EFI_ADDR_REDUND
+					+ CONFIG_ENV_EFI_SECT_SIZE - 1;
+#else
+		flash_addr_new = NULL;
+		end_addr_new = 0;
+#endif /* CONFIG_ENV_EFI_ADDR_REDUND */
+
+		ret = env_flash_init_params(ctx, env_ptr, flash_addr, end_addr,
+					    flash_addr_new, end_addr_new,
+					    NULL);
+		if (ret)
+			return -ENOENT;
+
+		return 0;
+		}
+#endif
+#ifdef CONFIG_ENV_EFI_IS_IN_FAT
+	case ENVL_FAT: {
+		ret = env_fat_init_params(ctx,
+					  CONFIG_ENV_EFI_FAT_INTERFACE,
+					  CONFIG_ENV_EFI_FAT_DEVICE_AND_PART,
+					  CONFIG_ENV_EFI_FAT_FILE);
+
+		return 0;
+		}
+#endif
+#ifdef CONFIG_ENV_DRV_NONE
+	case ENVL_NOWHERE:
+#ifdef CONFIG_ENV_EFI_IS_NOWHERE
+		/* TODO: what we should do */
+
+		return -ENOENT;
+#else
+		return -ENOENT;
+#endif
+#endif
+	default:
+		return -ENOENT;
+	}
+}
+
+/*
+ * Env context for UEFI variables
+ */
+U_BOOT_ENV_CONTEXT(efi) = {
+	.name = "efi",
+	.htab = &efi_htab,
+	.env_size = 0x10000, /* TODO: make this configurable */
+	.drv_init = env_drv_init_efi,
+};
+
+static int env_ctx_init_efi_volatile(struct env_context *ctx)
+{
+	/* Dummy table creation, or hcreate_r()? */
+	if (!himport_r(ctx->htab, NULL, 0, 0, 0, 0, 0, NULL)) {
+		debug("%s: Creating entry tables failed (ret=%d)\n", __func__,
+		      errno);
+		return errno;
+	}
+
+	env_set_ready(ctx);
+
+	return 0;
+}
+
+U_BOOT_ENV_CONTEXT(efi_volatile) = {
+	.name = "efi_volatile",
+	.htab = &efi_volatile_htab,
+	.env_size = 0,
+	.init = env_ctx_init_efi_volatile,
+};
diff --git a/include/env.h b/include/env.h
index 8045dda9f811..ec241d419a8a 100644
--- a/include/env.h
+++ b/include/env.h
@@ -66,6 +66,9 @@ enum env_redund_flags {
 };
 
 #define ctx_uboot ll_entry_get(struct env_context, uboot, env_contexts)
+#define ctx_efi ll_entry_get(struct env_context, efi, env_contexts)
+#define ctx_efi_volatile ll_entry_get(struct env_context, efi_volatile, \
+				      env_contexts)
 
 /* Accessor functions */
 void env_set_ready(struct env_context *ctx);
-- 
2.21.0