common: add generic system partitions interface

Both Fastboot and DFU have their own global variables that allow
specifying the partitions that can be flashed via the environment.
With the upcoming addition of the USB mass storage gadget, we will need
some way to define the partitions there as well.

Instead of adding yet another way download method-specific variable,
add a generic global.system.partitions variable that can be specified on a
per-board basis and can be used for all methods.

Existing variables will still remain for backwards-compatibility, but
when unset, it should fall back to this new parameter. This is done
in the follow-up patches.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.barebox.org/20210503114901.13095-7-a.fatoum@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

6 files changed, 116 insertions, 0 deletions

diff --git a/common/Kconfig b/common/Kconfig
index bf8054028b..5eb74cabd0 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -703,6 +703,17 @@ config FLEXIBLE_BOOTARGS
 config BAREBOX_UPDATE
 	bool "In-system barebox update infrastructure"
 
+config SYSTEM_PARTITIONS
+	bool "Generic system partitions support"
+	depends on GLOBALVAR
+	help
+	  System partitions are a generic way for boards to specify the
+	  partitions that should be exported for flashing.
+	  Board drivers that set this directly will select this option
+	  automatically.
+	  Say y here if this should be configurable over the
+	  global.system.partitions device parameter as well.
+
 config IMD
 	select CRC32
 	bool "barebox metadata support"
diff --git a/common/Makefile b/common/Makefile
index 17e2ff1129..c2c15817ba 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -17,6 +17,7 @@ obj-$(CONFIG_MACHINE_ID)	+= machine_id.o
 obj-$(CONFIG_AUTO_COMPLETE)	+= complete.o
 obj-y				+= version.o
 obj-$(CONFIG_BAREBOX_UPDATE)	+= bbu.o
+obj-$(CONFIG_SYSTEM_PARTITIONS) += system-partitions.o
 obj-$(CONFIG_BINFMT)		+= binfmt.o
 obj-$(CONFIG_BLOCK)		+= block.o
 obj-$(CONFIG_BLSPEC)		+= blspec.o
diff --git a/common/file-list.c b/common/file-list.c
index 924903cef7..580423aef7 100644
--- a/common/file-list.c
+++ b/common/file-list.c
@@ -170,6 +170,24 @@ void file_list_free(struct file_list *files)
 	free(files);
 }
 
+struct file_list *file_list_dup(struct file_list *old)
+{
+	struct file_list_entry *old_entry;
+	struct file_list *new;
+
+	new = xzalloc(sizeof(*new));
+
+	INIT_LIST_HEAD(&new->list);
+
+	list_for_each_entry(old_entry, &old->list, list) {
+		(void)file_list_add_entry(new, old_entry->name, old_entry->filename,
+					  old_entry->flags); /* can't fail */
+		new->num_entries++;
+	}
+
+	return new;
+}
+
 char *file_list_to_str(const struct file_list *files)
 {
 	struct file_list_entry *entry;
diff --git a/common/system-partitions.c b/common/system-partitions.c
new file mode 100644
index 0000000000..547e08a9f3
--- /dev/null
+++ b/common/system-partitions.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021 Ahmad Fatoum, Pengutronix
+ */
+
+#include <file-list.h>
+#include <param.h>
+#include <globalvar.h>
+#include <init.h>
+#include <magicvar.h>
+#include <system-partitions.h>
+
+static struct file_list *system_partitions;
+
+bool system_partitions_empty(void)
+{
+	return file_list_empty(system_partitions);
+}
+
+struct file_list *system_partitions_get(void)
+{
+	return file_list_dup(system_partitions);
+}
+
+void system_partitions_set(struct file_list *files)
+{
+	file_list_free(system_partitions);
+	system_partitions = files;
+}
+
+static int system_partitions_var_init(void)
+{
+	struct param_d *param;
+
+	system_partitions = file_list_parse("");
+	param = dev_add_param_file_list(&global_device, "system.partitions",
+					NULL, NULL, &system_partitions, NULL);
+
+	return PTR_ERR_OR_ZERO(param);
+}
+postcore_initcall(system_partitions_var_init);
+
+BAREBOX_MAGICVAR(global.system.partitions,
+		 "board-specific list of updatable partitions");
diff --git a/include/file-list.h b/include/file-list.h
index 7264a3e2c6..2538883c36 100644
--- a/include/file-list.h
+++ b/include/file-list.h
@@ -28,6 +28,8 @@ void file_list_free(struct file_list *);
 int file_list_add_entry(struct file_list *files, const char *name, const char *filename,
 			unsigned long flags);
 
+struct file_list *file_list_dup(struct file_list *old);
+
 struct file_list_entry *file_list_entry_by_name(struct file_list *files, const char *name);
 
 #define file_list_for_each_entry(files, entry) \
diff --git a/include/system-partitions.h b/include/system-partitions.h
new file mode 100644
index 0000000000..86de3612cc
--- /dev/null
+++ b/include/system-partitions.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef SYSTEM_PARTITIONS_H_
+#define SYSTEM_PARTITIONS_H_
+
+#include <file-list.h>
+
+#ifdef CONFIG_SYSTEM_PARTITIONS
+
+/* duplicates current system_partitions and returns it */
+struct file_list *system_partitions_get(void);
+
+/* takes ownership of files and store it internally */
+void system_partitions_set(struct file_list *files);
+
+/*
+ * check whether system_partitions_get would return an empty
+ * file_list without doing an allocation
+ */
+bool system_partitions_empty(void);
+
+#else
+
+static inline struct file_list *system_partitions_get(void)
+{
+	return file_list_parse("");
+}
+
+static inline bool system_partitions_empty(void)
+{
+	return true;
+}
+
+/*
+ * system_partitions_set() intentionally left unimplemented.
+ * select CONFIG_SYSTEM_PARTITIONS if you want to set it
+ */
+
+#endif
+
+#endif