We have previously added logic to allow a "fallback" option to be
specified in the extlinux configuration. Provide a command that allows
us to set this as the preferred default option when booting.

Combined with the bootcount functionality, this allows the "altbootcmd"
to provide a means of falling back to a previously known good state
after a failed update. For example, if "bootcmd" is set to:

    bootflow scan -lb

We would set "altbootcmd" to:

    bootmeth set extlinux fallback 1; bootflow scan -lb

Causing the boot process to boot from the fallback option.

Signed-off-by: Martyn Welch <martyn.we...@collabora.com>
---
 boot/bootmeth-uclass.c   | 25 ++++++++++++++
 boot/bootmeth_extlinux.c | 73 +++++++++++++++++++++++++++++++++++++++-
 cmd/bootmeth.c           | 25 ++++++++++++--
 include/bootmeth.h       | 31 +++++++++++++++++
 4 files changed, 151 insertions(+), 3 deletions(-)

diff --git a/boot/bootmeth-uclass.c b/boot/bootmeth-uclass.c
index c0abadef97..5b5fea39b3 100644
--- a/boot/bootmeth-uclass.c
+++ b/boot/bootmeth-uclass.c
@@ -251,6 +251,31 @@ int bootmeth_set_order(const char *order_str)
        return 0;
 }
 
+int bootmeth_set_property(const char *name, const char *property, const char 
*value)
+{
+       int ret;
+       int len;
+       struct udevice *dev;
+       const struct bootmeth_ops *ops;
+
+       len = strlen(name);
+
+       ret = uclass_find_device_by_namelen(UCLASS_BOOTMETH, name, len,
+                                           &dev);
+       if (ret) {
+               printf("Unknown bootmeth '%s'\n", name);
+               return ret;
+       }
+
+       ops = bootmeth_get_ops(dev);
+       if (!ops->set_property) {
+               printf("set_property not found\n");
+               return -ENODEV;
+       }
+
+       return ops->set_property(dev, property, value);
+}
+
 int bootmeth_setup_fs(struct bootflow *bflow, struct blk_desc *desc)
 {
        int ret;
diff --git a/boot/bootmeth_extlinux.c b/boot/bootmeth_extlinux.c
index 26c61a65e2..be8fbf4df6 100644
--- a/boot/bootmeth_extlinux.c
+++ b/boot/bootmeth_extlinux.c
@@ -21,6 +21,39 @@
 #include <mmc.h>
 #include <pxe_utils.h>
 
+struct extlinux_plat {
+       bool use_fallback;
+};
+
+enum extlinux_option_type {
+       EO_FALLBACK,
+       EO_INVALID
+};
+
+struct extlinux_option {
+       char *name;
+       enum extlinux_option_type option;
+};
+
+static const struct extlinux_option options[] = {
+       {"fallback", EO_FALLBACK},
+       {NULL, EO_INVALID}
+};
+
+static enum extlinux_option_type get_option(const char *option)
+{
+       int i = 0;
+
+       while (options[i].name) {
+               if (!strcmp(options[i].name, option))
+                       return options[i].option;
+
+               i++;
+       }
+
+       return EO_INVALID;
+};
+
 static int extlinux_get_state_desc(struct udevice *dev, char *buf, int maxsize)
 {
        if (IS_ENABLED(CONFIG_SANDBOX)) {
@@ -142,14 +175,18 @@ static int extlinux_boot(struct udevice *dev, struct 
bootflow *bflow)
        struct cmd_tbl cmdtp = {};      /* dummy */
        struct pxe_context ctx;
        struct extlinux_info info;
+       struct extlinux_plat *plat;
        ulong addr;
        int ret;
 
        addr = map_to_sysmem(bflow->buf);
        info.dev = dev;
        info.bflow = bflow;
+
+       plat = dev_get_plat(dev);
+
        ret = pxe_setup_ctx(&ctx, &cmdtp, extlinux_getfile, &info, true,
-                           bflow->fname, false, false);
+                           bflow->fname, false, plat->use_fallback);
        if (ret)
                return log_msg_ret("ctx", -EINVAL);
 
@@ -160,6 +197,38 @@ static int extlinux_boot(struct udevice *dev, struct 
bootflow *bflow)
        return 0;
 }
 
+static int extlinux_set_property(struct udevice *dev, const char *property, 
const char *value)
+{
+       struct extlinux_plat *plat;
+       static enum extlinux_option_type option;
+
+       plat = dev_get_plat(dev);
+
+       option = get_option(property);
+       if (option == EO_INVALID) {
+               printf("Invalid option\n");
+               return -EINVAL;
+       }
+
+       switch (option) {
+       case EO_FALLBACK:
+               if (!strcmp(value, "1")) {
+                       plat->use_fallback = true;
+               } else if (!strcmp(value, "0")) {
+                       plat->use_fallback = false;
+               } else {
+                       printf("Unexpected value '%s'\n", value);
+                       return -EINVAL;
+               }
+               break;
+       default:
+               printf("Unrecognised property '%s'\n", property);
+               return -EINVAL;
+       }
+
+       return 0;
+}
+
 static int extlinux_bootmeth_bind(struct udevice *dev)
 {
        struct bootmeth_uc_plat *plat = dev_get_uclass_plat(dev);
@@ -176,6 +245,7 @@ static struct bootmeth_ops extlinux_bootmeth_ops = {
        .read_bootflow  = extlinux_read_bootflow,
        .read_file      = bootmeth_common_read_file,
        .boot           = extlinux_boot,
+       .set_property   = extlinux_set_property,
 };
 
 static const struct udevice_id extlinux_bootmeth_ids[] = {
@@ -190,4 +260,5 @@ U_BOOT_DRIVER(bootmeth_1extlinux) = {
        .of_match       = extlinux_bootmeth_ids,
        .ops            = &extlinux_bootmeth_ops,
        .bind           = extlinux_bootmeth_bind,
+       .plat_auto      = sizeof(struct extlinux_plat)
 };
diff --git a/cmd/bootmeth.c b/cmd/bootmeth.c
index ebf8b7e253..2f41fa1bec 100644
--- a/cmd/bootmeth.c
+++ b/cmd/bootmeth.c
@@ -103,10 +103,31 @@ static int do_bootmeth_order(struct cmd_tbl *cmdtp, int 
flag, int argc,
        return 0;
 }
 
+static int do_bootmeth_set(struct cmd_tbl *cmdtp, int flag, int argc,
+                            char *const argv[])
+{
+       int ret;
+
+       if (argc < 4) {
+               printf("Required parameters not provided\n");
+               return CMD_RET_FAILURE;
+       }
+
+       ret = bootmeth_set_property(argv[1], argv[2], argv[3]);
+       if (ret) {
+               printf("Failed (err=%d)\n", ret);
+               return CMD_RET_FAILURE;
+       }
+
+       return 0;
+}
+
 U_BOOT_LONGHELP(bootmeth,
        "list [-a]     - list available bootmeths (-a all)\n"
-       "bootmeth order [<bd> ...]  - select bootmeth order / subset to use");
+       "bootmeth order [<bd> ...]  - select bootmeth order / subset to use\n"
+       "bootmeth set <bootmeth> <property> <value> - set optional property");
 
 U_BOOT_CMD_WITH_SUBCMDS(bootmeth, "Boot methods", bootmeth_help_text,
        U_BOOT_SUBCMD_MKENT(list, 2, 1, do_bootmeth_list),
-       U_BOOT_SUBCMD_MKENT(order, CONFIG_SYS_MAXARGS, 1, do_bootmeth_order));
+       U_BOOT_SUBCMD_MKENT(order, CONFIG_SYS_MAXARGS, 1, do_bootmeth_order),
+       U_BOOT_SUBCMD_MKENT(set, CONFIG_SYS_MAXARGS, 1, do_bootmeth_set));
diff --git a/include/bootmeth.h b/include/bootmeth.h
index 4d8ca48efd..a08ebf005a 100644
--- a/include/bootmeth.h
+++ b/include/bootmeth.h
@@ -146,6 +146,22 @@ struct bootmeth_ops {
         *      something changes, other -ve on other error
         */
        int (*boot)(struct udevice *dev, struct bootflow *bflow);
+
+       /**
+        * set_property() - set the bootmeth property
+        *
+        * This allows the setting of boot method specific properties to enable
+        * automated finer grain control of the boot process
+        *
+        * @name: String containing the name of the relevant boot method
+        * @property: String containing the name of the property to set
+        * @value: String containing the value to be set for the specified
+        *         property
+        * Return: 0 if OK, -ENODEV if an unknown bootmeth or property is
+        *      provided, -ENOENT if there are no bootmeth devices
+        */
+       int (*set_property)(struct udevice *dev, const char *property,
+                           const char *value);
 };
 
 #define bootmeth_get_ops(dev)  ((struct bootmeth_ops *)(dev)->driver->ops)
@@ -290,6 +306,21 @@ int bootmeth_setup_iter_order(struct bootflow_iter *iter, 
bool include_global);
  */
 int bootmeth_set_order(const char *order_str);
 
+/**
+ * bootmeth_set_property() - Set the bootmeth property
+ *
+ * This allows the setting of boot method specific properties to enable
+ * automated finer grain control of the boot process
+ *
+ * @name: String containing the name of the relevant boot method
+ * @property: String containing the name of the property to set
+ * @value: String containing the value to be set for the specified property
+ * Return: 0 if OK, -ENODEV if an unknown bootmeth or property is provided,
+ * -ENOENT if there are no bootmeth devices
+ */
+int bootmeth_set_property(const char *name, const char *property,
+                         const char *value);
+
 /**
  * bootmeth_setup_fs() - Set up read to read a file
  *
-- 
2.45.2

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