/* Nota bene: avm-prom/prom-getenv-tffs.c is only for early development, as
 * it uses the TFFS function avm_urlader_env_get_value() which does not work
 * properly before mtd and TFFS initialisation is complete.
 */
#include <linux/module.h>
#include <linux/slab.h>
#include <avm/tffs/tffs.h>
#include <linux/notifier.h>

static bool prom_env_initialized;
static LIST_HEAD(prom_list);

struct prom_entry {
	char *name;
	char *value;
	struct list_head list;
};

static int prom_env_add(const char *env_name, char *env_value)
{
	struct prom_entry *entry;

	if (!env_name || !env_value)
		return -EINVAL;

	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
	if (!entry)
		return -ENOMEM;
	entry->name = kstrdup(env_name, GFP_KERNEL);
	if (!entry->name)
		goto err;

	/* env_value was allocated in memory by avm_urlader_env_get_value().
	 * prom_list now owns this memory and all responsibilities that follow
	 */
	entry->value = env_value;

	list_add_tail(&entry->list, &prom_list);

	return 0;

err:
	kfree(entry);
	return -ENOMEM;
}

static int prom_env_init(struct notifier_block *nb, unsigned long action,
			 void *data)
{
	enum tffs3_module_state state = (enum tffs3_module_state)action;
	const struct _TFFS_Name_Table *tffs_env;
	char *tffs_env_val;
	int ret;

	if (state != tffs3_module_running)
		return NOTIFY_DONE;

	for (tffs_env = avm_urlader_get_nametable();
			tffs_env && tffs_env->id; tffs_env++) {
		if (tffs_env->id == FLASH_FS_TABLE_VERSION ||
		    tffs_env->id == FLASH_FS_NAME_TABLE)
			continue;

		tffs_env_val = avm_urlader_env_get_value(tffs_env->Name);
		if (!tffs_env_val)
			continue;

		ret = prom_env_add(tffs_env->Name, tffs_env_val);
		if (ret)
			goto err_out;
	}

	/* We want to ensure that prom_env_initialized isn't set before
	 * before it is actually initialized
	 */
	smp_store_release(&prom_env_initialized, true);

	return NOTIFY_OK;

err_out:
	kfree(tffs_env_val);
	pr_err("Error reading urlader environment from TFFS (%d): prom_getenv won't work\n", ret);
	return NOTIFY_DONE;
}

static struct notifier_block tffs_notify_ready = {
	.notifier_call = prom_env_init,
};

static int __init prom_env_register_tffs_notifier(void)
{
	return blocking_notifier_chain_register(&tffs_state_notifier,
						&tffs_notify_ready);
}
device_initcall(prom_env_register_tffs_notifier);

char *prom_getenv(char *var)
{
	struct prom_entry *entry;

	if (!var || !prom_env_initialized)
		return NULL;

	list_for_each_entry(entry, &prom_list, list)
		if (!strcmp(entry->name, var))
			return entry->value;

	return NULL;
}
EXPORT_SYMBOL(prom_getenv);

MODULE_AUTHOR("AVM GmbH");
MODULE_DESCRIPTION("AVM prom_getenv() via TFFS (for development only)");
MODULE_LICENSE("GPL");