[PATCH PREVIEW RFC 4/6] base: bootcache: Add bootcache test backend

[acampanella-thegoodpenguin <acampanella@thegoodpenguin.co.uk>]

From: Marc Kelly <mkelly@thegoodpenguin.co.uk>

bootcache_backend_test provides a simple test backend of API
demonstration and testing purposes.

Signed-off-by: Marc Kelly <mkelly@thegoodpenguin.co.uk>
---
 MAINTAINERS                           |   2 +
 drivers/base/Kconfig                  |  14 ++++
 drivers/base/Makefile                 |   1 +
 drivers/base/bootcache_backend_test.c | 119 ++++++++++++++++++++++++++++++++++
 4 files changed, 136 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 4bf3766b30bbf75214911bd4ce5256a066f05726..73679686d49ac653382ecb32b9b3b500a4509383 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4420,8 +4420,10 @@ F:	drivers/iio/imu/bmi323/
 
 BOOT CACHE
 M:	Andrea Campanella <acampanella@thegoodpenguin.co.uk>
+M:	Marc Kelly <mkelly@thegoodpenguin.co.uk>
 S:	Maintained
 F:	drivers/base/bootcache.c
+F:	drivers/base/bootcache_*
 F:	include/linux/bootcache.h
 
 BPF JIT for ARC
diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index da02f95948d880da83c3025addc1e111dbce339a..1303364993ff4bf7fbbc210243dc6dc48fb1bd83 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -84,6 +84,20 @@ config BOOTCACHE
 
 	  If unsure, say N.
 
+	if BOOTCACHE
+	choice
+		prompt "Boot-time cache backend"
+		depends on BOOTCACHE
+
+	config BOOTCACHE_BACKEND_TEST
+		bool "Test backend"
+		help
+		  A simple backend for testing and development.
+		  It does not persist any data externally.
+
+	endchoice
+	endif
+
 config STANDALONE
 	bool "Select only drivers that don't need compile-time external firmware"
 	default y
diff --git a/drivers/base/Makefile b/drivers/base/Makefile
index 10a16e6c2ea1ad778fb7793583b9ee54d2498b2b..dc87c21cd79468045878c4b3cef5714c12f65ec4 100644
--- a/drivers/base/Makefile
+++ b/drivers/base/Makefile
@@ -9,6 +9,7 @@ obj-y			:= component.o core.o bus.o dd.o syscore.o \
 			   swnode.o faux.o
 obj-$(CONFIG_AUXILIARY_BUS) += auxiliary.o
 obj-$(CONFIG_BOOTCACHE)    += bootcache.o
+obj-$(CONFIG_BOOTCACHE_BACKEND_TEST)    += bootcache_backend_test.o
 obj-$(CONFIG_DEVTMPFS)	+= devtmpfs.o
 obj-y			+= power/
 obj-$(CONFIG_ISA_BUS_API)	+= isa.o
diff --git a/drivers/base/bootcache_backend_test.c b/drivers/base/bootcache_backend_test.c
new file mode 100644
index 0000000000000000000000000000000000000000..b44b4802fb99aa70c731017c503c6084796e90ae
--- /dev/null
+++ b/drivers/base/bootcache_backend_test.c
@@ -0,0 +1,119 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/hashtable.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
+
+#include <linux/bootcache.h>
+
+#define DRIVER_NAME "bootcache_test_backend"
+
+struct test_data {
+	const char *name;
+	u32 value;
+	size_t data_length;
+};
+
+static struct test_data test_data_array[] = {
+	{
+		.name = "Bootcache Test One",
+		.value = 1234,
+		.data_length = sizeof(u32),
+	},
+	{
+		.name = "Bootcache Test Two",
+		.value = 5678,
+		.data_length = sizeof(u32),
+	},
+	{
+		.name = "Bootcache Test Three",
+		.value = 9012,
+		.data_length = sizeof(u32),
+	},
+	{
+		.name = "Bootcache Test Four",
+		.value = 0xDEADBEEF,
+		.data_length = sizeof(u32),
+	},
+	{
+		.name = "Bootcache Test Five",
+		.value = 0xC0DEBAD0,
+		.data_length = sizeof(u32),
+	}
+};
+
+static int test_backend_load_cache(void)
+{
+
+	struct bootcache_entry *new_entry = NULL;
+	int i;
+	int ret;
+
+	pr_info("%s: Backend local_cache callback\n", DRIVER_NAME);
+
+	/*
+	 * We want to load a bunch of fake data into the cache here
+	 * so that it can be used for testing purposes
+	 */
+	for (i = 0; i < ARRAY_SIZE(test_data_array); i++) {
+		/*
+		 * Print the name and value of the current element.
+		 * Use pr_info for a standard kernel log message.
+		 */
+		new_entry = kzalloc(sizeof(*new_entry), GFP_KERNEL);
+		if (!new_entry)
+			return -ENOMEM;
+
+		new_entry->key = kstrdup(test_data_array[i].name, GFP_KERNEL);
+		if (!new_entry->key) {
+			kfree(new_entry);
+			return -ENOMEM;
+		}
+		new_entry->len = test_data_array[i].data_length;
+		new_entry->data = kmemdup(&test_data_array[i].value,
+			test_data_array[i].data_length, GFP_KERNEL);
+		if (!new_entry->data) {
+			kfree(new_entry->key);
+			kfree(new_entry);
+			return -ENOMEM;
+		}
+
+		/* call the framework provided function */
+		ret = bootcache_add_entry(new_entry);
+		if (ret) {
+			kfree(new_entry->key);
+			kfree(new_entry->data);
+			kfree(new_entry);
+			ret = 0;
+		}
+	}
+	return 0;
+}
+
+static struct bootcache_info cache_info = {
+	.name = "test",
+	.load_cache = test_backend_load_cache,
+};
+
+static int __init bootcache_backend_init(void)
+{
+	int ret;
+
+	ret = bootcache_register_backend(&cache_info);
+
+	if (ret < 0) {
+		pr_err("%s: bootcache_register_backend() failed with error %d\n",
+			DRIVER_NAME, ret);
+		return ret;
+	}
+	pr_info("%s: Backend loaded\n", DRIVER_NAME);
+
+	return 0;
+}
+
+core_initcall(bootcache_backend_init);

-- 
2.48.1