generic: platform/mikrotik: use MTD notifier

If the SPI probe is sufficiently delayed, the routerboot driver may fail
to init as the routerboot partitions are not yet available.

Register an MTD user notifier instead of doing straight init so that the
init subroutines are only executed when the target MTD partitions are
present.

Because the init/exit routines can now be called outside of the kernel
normal init/exit calls, they cannot be jettisoned and must always be
available: the __init and __exit qualifiers are thus removed.

Reported-by: Denis Kalashnikov <[email protected]>
Signed-off-by: Denis Kalashnikov <[email protected]>
Signed-off-by: Thibaut VARÈNE <[email protected]>
Reviewed-by: Sergey Ryazanov <[email protected]>
[bump hardconfig/softconfig versions]
Signed-off-by: Koen Vandeputte <[email protected]>

target/linux/generic/files/drivers/platform/mikrotik/rb_hardconfig.c

@@ -39,7 +39,7 @@
 
 #include "routerboot.h"
 
-#define RB_HARDCONFIG_VER		"0.06"
+#define RB_HARDCONFIG_VER		"0.07"
 #define RB_HC_PR_PFX			"[rb_hardconfig] "
 
 /* ID values for hardware settings */
@@ -676,10 +676,9 @@ static ssize_t hc_wlan_data_bin_read(struct file *filp, struct kobject *kobj,
 	return count;
 }
 
-int __init rb_hardconfig_init(struct kobject *rb_kobj)
+int rb_hardconfig_init(struct kobject *rb_kobj, struct mtd_info *mtd)
 {
 	struct kobject *hc_wlan_kobj;
-	struct mtd_info *mtd;
 	size_t bytes_read, buflen, outlen;
 	const u8 *buf;
 	void *outbuf;
@@ -690,20 +689,19 @@ int __init rb_hardconfig_init(struct kobject *rb_kobj)
 	hc_kobj = NULL;
 	hc_wlan_kobj = NULL;
 
-	// TODO allow override
-	mtd = get_mtd_device_nm(RB_MTD_HARD_CONFIG);
-	if (IS_ERR(mtd))
+	ret = __get_mtd_device(mtd);
+	if (ret)
 		return -ENODEV;
 
 	hc_buflen = mtd->size;
 	hc_buf = kmalloc(hc_buflen, GFP_KERNEL);
 	if (!hc_buf) {
-		put_mtd_device(mtd);
+		__put_mtd_device(mtd);
 		return -ENOMEM;
 	}
 
 	ret = mtd_read(mtd, 0, hc_buflen, &bytes_read, hc_buf);
-	put_mtd_device(mtd);
+	__put_mtd_device(mtd);
 
 	if (ret)
 		goto fail;
@@ -818,8 +816,10 @@ fail:
 	return ret;
 }
 
-void __exit rb_hardconfig_exit(void)
+void rb_hardconfig_exit(void)
 {
 	kobject_put(hc_kobj);
+	hc_kobj = NULL;
 	kfree(hc_buf);
+	hc_buf = NULL;
 }

target/linux/generic/files/drivers/platform/mikrotik/rb_softconfig.c

@@ -56,7 +56,7 @@
 
 #include "routerboot.h"
 
-#define RB_SOFTCONFIG_VER		"0.04"
+#define RB_SOFTCONFIG_VER		"0.05"
 #define RB_SC_PR_PFX			"[rb_softconfig] "
 
 #define RB_SC_HAS_WRITE_SUPPORT	true
@@ -694,9 +694,8 @@ mtdfail:
 
 static struct kobj_attribute sc_kattrcommit = __ATTR(commit, RB_SC_RMODE|RB_SC_WMODE, sc_commit_show, sc_commit_store);
 
-int __init rb_softconfig_init(struct kobject *rb_kobj)
+int rb_softconfig_init(struct kobject *rb_kobj, struct mtd_info *mtd)
 {
-	struct mtd_info *mtd;
 	size_t bytes_read, buflen;
 	const u8 *buf;
 	int i, ret;
@@ -705,20 +704,19 @@ int __init rb_softconfig_init(struct kobject *rb_kobj)
 	sc_buf = NULL;
 	sc_kobj = NULL;
 
-	// TODO allow override
-	mtd = get_mtd_device_nm(RB_MTD_SOFT_CONFIG);
-	if (IS_ERR(mtd))
+	ret = __get_mtd_device(mtd);
+	if (ret)
 		return -ENODEV;
 
 	sc_buflen = mtd->size;
 	sc_buf = kmalloc(sc_buflen, GFP_KERNEL);
 	if (!sc_buf) {
-		put_mtd_device(mtd);
+		__put_mtd_device(mtd);
 		return -ENOMEM;
 	}
 
 	ret = mtd_read(mtd, 0, sc_buflen, &bytes_read, sc_buf);
-	put_mtd_device(mtd);
+	__put_mtd_device(mtd);
 
 	if (ret)
 		goto fail;
@@ -788,8 +786,10 @@ fail:
 	return ret;
 }
 
-void __exit rb_softconfig_exit(void)
+void rb_softconfig_exit(void)
 {
 	kobject_put(sc_kobj);
+	sc_kobj = NULL;
 	kfree(sc_buf);
+	sc_buf = NULL;
 }

target/linux/generic/files/drivers/platform/mikrotik/routerboot.c

@@ -13,6 +13,7 @@
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/sysfs.h>
+#include <linux/mtd/mtd.h>
 
 #include "routerboot.h"
 
@@ -160,25 +161,57 @@ fail:
 	return ret;
 }
 
-static int __init routerboot_init(void)
+static void routerboot_mtd_notifier_add(struct mtd_info *mtd)
 {
-	rb_kobj = kobject_create_and_add("mikrotik", firmware_kobj);
-	if (!rb_kobj)
-		return -ENOMEM;
+	/* Currently routerboot is only known to live on NOR flash */
+	if (mtd->type != MTD_NORFLASH)
+		return;
 
 	/*
 	 * We ignore the following return values and always register.
 	 * These init() routines are designed so that their failed state is
 	 * always manageable by the corresponding exit() calls.
+	 * Notifier is called with MTD mutex held: use __get/__put variants.
+	 * TODO: allow partition names override
 	 */
-	rb_hardconfig_init(rb_kobj);
-	rb_softconfig_init(rb_kobj);
+	if (!strcmp(mtd->name, RB_MTD_HARD_CONFIG))
+		rb_hardconfig_init(rb_kobj, mtd);
+	else if (!strcmp(mtd->name, RB_MTD_SOFT_CONFIG))
+		rb_softconfig_init(rb_kobj, mtd);
+}
+
+static void routerboot_mtd_notifier_remove(struct mtd_info *mtd)
+{
+	if (mtd->type != MTD_NORFLASH)
+		return;
+
+	if (!strcmp(mtd->name, RB_MTD_HARD_CONFIG))
+		rb_hardconfig_exit();
+	else if (!strcmp(mtd->name, RB_MTD_SOFT_CONFIG))
+		rb_softconfig_exit();
+}
+
+/* Note: using a notifier prevents qualifying init()/exit() functions with __init/__exit */
+static struct mtd_notifier routerboot_mtd_notifier = {
+	.add = routerboot_mtd_notifier_add,
+	.remove = routerboot_mtd_notifier_remove,
+};
+
+static int __init routerboot_init(void)
+{
+	rb_kobj = kobject_create_and_add("mikrotik", firmware_kobj);
+	if (!rb_kobj)
+		return -ENOMEM;
+
+	register_mtd_user(&routerboot_mtd_notifier);
 
 	return 0;
 }
 
 static void __exit routerboot_exit(void)
 {
+	unregister_mtd_user(&routerboot_mtd_notifier);
+	/* Exit routines are idempotent */
 	rb_softconfig_exit();
 	rb_hardconfig_exit();
 	kobject_put(rb_kobj);	// recursive afaict

target/linux/generic/files/drivers/platform/mikrotik/routerboot.h

@@ -25,11 +25,11 @@
 int routerboot_tag_find(const u8 *bufhead, const size_t buflen, const u16 tag_id, u16 *pld_ofs, u16 *pld_len);
 int routerboot_rle_decode(const u8 *in, size_t inlen, u8 *out, size_t *outlen);
 
-int __init rb_hardconfig_init(struct kobject *rb_kobj);
-void __exit rb_hardconfig_exit(void);
+int rb_hardconfig_init(struct kobject *rb_kobj, struct mtd_info *mtd);
+void rb_hardconfig_exit(void);
 
-int __init rb_softconfig_init(struct kobject *rb_kobj);
-void __exit rb_softconfig_exit(void);
+int rb_softconfig_init(struct kobject *rb_kobj, struct mtd_info *mtd);
+void rb_softconfig_exit(void);
 
 ssize_t routerboot_tag_show_string(const u8 *pld, u16 pld_len, char *buf);
 ssize_t routerboot_tag_show_u32s(const u8 *pld, u16 pld_len, char *buf);