Expose firmware paths via procfs

index 8154145..2153eab 100644
@@ -36,13 +36,13 @@ MODULE_AUTHOR("Manuel Estrada Sainz");
 MODULE_DESCRIPTION("Multi purpose firmware loading support");
 MODULE_LICENSE("GPL");
 
-static const char *fw_path[] = {
-	"/lib/firmware/updates/" UTS_RELEASE,
-	"/lib/firmware/updates",
-	"/lib/firmware/" UTS_RELEASE,
-	"/lib/firmware"
+struct fw_path_rec {
+	const char *name;
+	struct list_head list;
 };
 
+static LIST_HEAD(fw_path_list);
+
 /* Don't inline this: 'struct kstat' is biggish */
 static noinline long fw_file_size(struct file *file)
 {

@@ -78,13 +78,14 @@ static bool fw_read_file_contents(struct file *file, struct firmware *fw)
 
 static bool fw_get_filesystem_firmware(struct firmware *fw, const char *name)
 {
-	int i;
 	bool success = false;
 	char *path = __getname();
+	struct fw_path_rec *fwp;
 
-	for (i = 0; i < ARRAY_SIZE(fw_path); i++) {
+	list_for_each_entry(fwp, &fw_path_list, list) {
 		struct file *file;
-		snprintf(path, PATH_MAX, "%s/%s", fw_path[i], name);
+		snprintf(path, PATH_MAX, "%s/%s", fwp->name,
+			 name);
 
 		file = filp_open(path, O_RDONLY, 0);
 		if (IS_ERR(file))

@@ -1385,6 +1386,50 @@ static int fw_cache_piggyback_on_request(const char *name)
 }
 #endif
 
+static void fw_free_path_list(void)
+{
+	struct fw_path_rec *fwp;
+
+	while (!list_empty(&fw_path_list)) {
+		fwp = list_first_entry(&fw_path_list,
+				       struct fw_path_rec,
+				       list);
+		kfree(fwp->name);
+		list_del(&fwp->list);
+		kfree(fwp);
+	}
+}
+
+static int fw_populate_path_list(void)
+{
+	int i;
+	struct fw_path_rec *fwp;
+	static const char *fw_path[] = {
+		"/lib/firmware/updates/" UTS_RELEASE,
+		"/lib/firmware/updates",
+		"/lib/firmware/" UTS_RELEASE,
+		"/lib/firmware"
+	};
+
+	for (i = 0; i < ARRAY_SIZE(fw_path); i++) {
+		fwp = kmalloc(sizeof(*fwp), GFP_KERNEL);
+		if (!fwp)
+			goto err_fwp_alloc;
+		fwp->name = kstrdup(fw_path[i], GFP_KERNEL);
+		if (!fwp->name)
+			goto err_fwp_name_alloc;
+		list_add_tail(&fwp->list, &fw_path_list);
+	}
+
+	return 0;
+
+err_fwp_name_alloc:
+	kfree(fwp);
+err_fwp_alloc:
+	fw_free_path_list();
+	return -ENOMEM;
+}
+
 static void __init fw_cache_init(void)
 {
 	spin_lock_init(&fw_cache.lock);

@@ -1409,7 +1454,17 @@ static void __init fw_cache_init(void)
 
 static int __init firmware_class_init(void)
 {
+	int ret;
+
 	fw_cache_init();
+
+	ret = fw_populate_path_list();
+	if (ret < 0) {
+		pr_err("%s: Failed to populate firmware path list: %d\n",
+		       __func__, ret);
+		return ret;
+	}
+
 	return class_register(&firmware_class);
 }
 

@@ -1419,6 +1474,7 @@ static void __exit firmware_class_exit(void)
 	unregister_syscore_ops(&fw_syscore_ops);
 	unregister_pm_notifier(&fw_cache.pm_notify);
 #endif
+	fw_free_path_list();
 	class_unregister(&firmware_class);
 }
 

index 2153eab..22cef4d 100644
@@ -27,6 +27,8 @@
 #include <linux/pm.h>
 #include <linux/suspend.h>
 #include <linux/syscore_ops.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
 
 #include <generated/utsrelease.h>
 

@@ -1430,6 +1432,56 @@ err_fwp_alloc:
 	return -ENOMEM;
 }
 
+static void *fw_path_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	return seq_list_start_head(&fw_path_list, *pos);
+}
+
+static void *fw_path_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	return seq_list_next(v, &fw_path_list, pos);
+}
+
+static int fw_path_seq_show(struct seq_file *seq, void *v)
+{
+	const struct fw_path_rec *fwp;
+	struct list_head *l = v;
+
+	if (l == &fw_path_list)
+		return 0;
+	fwp = list_entry(v, struct fw_path_rec, list);
+	seq_puts(seq, fwp->name);
+	if (l->next != &fw_path_list)
+		seq_putc(seq, ' ');
+	else
+		seq_putc(seq, '\n');
+	return 0;
+}
+
+static void fw_path_seq_stop(struct seq_file *seq, void *v)
+{
+}
+
+static const struct seq_operations fw_path_ops = {
+	.start = fw_path_seq_start,
+	.next = fw_path_seq_next,
+	.stop = fw_path_seq_stop,
+	.show = fw_path_seq_show,
+};
+
+static int fw_path_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &fw_path_ops);
+}
+
+static const struct file_operations fw_path_seq_fops = {
+	.owner = THIS_MODULE,
+	.open = fw_path_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = seq_release,
+};
+
 static void __init fw_cache_init(void)
 {
 	spin_lock_init(&fw_cache.lock);

@@ -1465,6 +1517,8 @@ static int __init firmware_class_init(void)
 		return ret;
 	}
 
+	proc_create("fw_path", S_IRUGO, NULL, &fw_path_seq_fops);
+
 	return class_register(&firmware_class);
 }
 

@@ -1474,6 +1528,7 @@ static void __exit firmware_class_exit(void)
 	unregister_syscore_ops(&fw_syscore_ops);
 	unregister_pm_notifier(&fw_cache.pm_notify);
 #endif
+	remove_proc_entry("fw_path", NULL);
 	fw_free_path_list();
 	class_unregister(&firmware_class);
 }