usb: gadget: f_mass_storage: add configfs support

From this commit on f_mass_storage is available through configfs.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

3 files changed, 388 insertions, 0 deletions

diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index 7d64e474c48b..bc5dea2f26e2 100644
--- a/drivers/usb/gadget/Kconfig
+++ b/drivers/usb/gadget/Kconfig
@@ -668,6 +668,17 @@ config USB_CONFIGFS_PHONET
         help
           The Phonet protocol implementation for USB device.
 
+config USB_CONFIGFS_MASS_STORAGE
+        boolean "Mass storage"
+        depends on USB_CONFIGFS
+        select USB_U_MS
+        select USB_F_MASS_STORAGE
+        help
+          The Mass Storage Gadget acts as a USB Mass Storage disk drive.
+          As its storage repository it can use a regular file or a block
+          device (in much the same way as the "loop" device driver),
+          specified as a module parameter or sysfs option.
+
 config USB_ZERO
         tristate "Gadget Zero (DEVELOPMENT)"
         select USB_LIBCOMPOSITE
diff --git a/drivers/usb/gadget/f_mass_storage.c b/drivers/usb/gadget/f_mass_storage.c
index d80be5f0e6d2..00d3687594bb 100644
--- a/drivers/usb/gadget/f_mass_storage.c
+++ b/drivers/usb/gadget/f_mass_storage.c
@@ -220,6 +220,7 @@
 #include <linux/usb/composite.h>
 
 #include "gadget_chips.h"
+#include "configfs.h"
 
 
 /*------------------------------------------------------------------------*/
@@ -3295,6 +3296,342 @@ static int fsg_bind_config(struct usb_composite_dev *cdev,
 
 #else
 
+static inline struct fsg_lun_opts *to_fsg_lun_opts(struct config_item *item)
+{
+        return container_of(to_config_group(item), struct fsg_lun_opts, group);
+}
+
+static inline struct fsg_opts *to_fsg_opts(struct config_item *item)
+{
+        return container_of(to_config_group(item), struct fsg_opts,
+                            func_inst.group);
+}
+
+CONFIGFS_ATTR_STRUCT(fsg_lun_opts);
+CONFIGFS_ATTR_OPS(fsg_lun_opts);
+
+static void fsg_lun_attr_release(struct config_item *item)
+{
+        struct fsg_lun_opts *lun_opts;
+
+        lun_opts = to_fsg_lun_opts(item);
+        kfree(lun_opts);
+}
+
+static struct configfs_item_operations fsg_lun_item_ops = {
+        .release        = fsg_lun_attr_release,
+        .show_attribute = fsg_lun_opts_attr_show,
+        .store_attribute = fsg_lun_opts_attr_store,
+};
+
+static ssize_t fsg_lun_opts_file_show(struct fsg_lun_opts *opts, char *page)
+{
+        struct fsg_opts *fsg_opts;
+
+        fsg_opts = to_fsg_opts(opts->group.cg_item.ci_parent);
+
+        return fsg_show_file(opts->lun, &fsg_opts->common->filesem, page);
+}
+
+static ssize_t fsg_lun_opts_file_store(struct fsg_lun_opts *opts,
+                                       const char *page, size_t len)
+{
+        struct fsg_opts *fsg_opts;
+
+        fsg_opts = to_fsg_opts(opts->group.cg_item.ci_parent);
+
+        return fsg_store_file(opts->lun, &fsg_opts->common->filesem, page, len);
+}
+
+static struct fsg_lun_opts_attribute fsg_lun_opts_file =
+        __CONFIGFS_ATTR(file, S_IRUGO | S_IWUSR, fsg_lun_opts_file_show,
+                        fsg_lun_opts_file_store);
+
+static ssize_t fsg_lun_opts_ro_show(struct fsg_lun_opts *opts, char *page)
+{
+        return fsg_show_ro(opts->lun, page);
+}
+
+static ssize_t fsg_lun_opts_ro_store(struct fsg_lun_opts *opts,
+                                       const char *page, size_t len)
+{
+        struct fsg_opts *fsg_opts;
+
+        fsg_opts = to_fsg_opts(opts->group.cg_item.ci_parent);
+
+        return fsg_store_ro(opts->lun, &fsg_opts->common->filesem, page, len);
+}
+
+static struct fsg_lun_opts_attribute fsg_lun_opts_ro =
+        __CONFIGFS_ATTR(ro, S_IRUGO | S_IWUSR, fsg_lun_opts_ro_show,
+                        fsg_lun_opts_ro_store);
+
+static ssize_t fsg_lun_opts_removable_show(struct fsg_lun_opts *opts,
+                                           char *page)
+{
+        return fsg_show_removable(opts->lun, page);
+}
+
+static ssize_t fsg_lun_opts_removable_store(struct fsg_lun_opts *opts,
+                                       const char *page, size_t len)
+{
+        return fsg_store_removable(opts->lun, page, len);
+}
+
+static struct fsg_lun_opts_attribute fsg_lun_opts_removable =
+        __CONFIGFS_ATTR(removable, S_IRUGO | S_IWUSR,
+                        fsg_lun_opts_removable_show,
+                        fsg_lun_opts_removable_store);
+
+static ssize_t fsg_lun_opts_cdrom_show(struct fsg_lun_opts *opts, char *page)
+{
+        return fsg_show_cdrom(opts->lun, page);
+}
+
+static ssize_t fsg_lun_opts_cdrom_store(struct fsg_lun_opts *opts,
+                                       const char *page, size_t len)
+{
+        return fsg_store_cdrom(opts->lun, page, len);
+}
+
+static struct fsg_lun_opts_attribute fsg_lun_opts_cdrom =
+        __CONFIGFS_ATTR(cdrom, S_IRUGO | S_IWUSR, fsg_lun_opts_cdrom_show,
+                        fsg_lun_opts_cdrom_store);
+
+static ssize_t fsg_lun_opts_nofua_show(struct fsg_lun_opts *opts, char *page)
+{
+        return fsg_show_nofua(opts->lun, page);
+}
+
+static ssize_t fsg_lun_opts_nofua_store(struct fsg_lun_opts *opts,
+                                       const char *page, size_t len)
+{
+        return fsg_store_nofua(opts->lun, page, len);
+}
+
+static struct fsg_lun_opts_attribute fsg_lun_opts_nofua =
+        __CONFIGFS_ATTR(nofua, S_IRUGO | S_IWUSR, fsg_lun_opts_nofua_show,
+                        fsg_lun_opts_nofua_store);
+
+static struct configfs_attribute *fsg_lun_attrs[] = {
+        &fsg_lun_opts_file.attr,
+        &fsg_lun_opts_ro.attr,
+        &fsg_lun_opts_removable.attr,
+        &fsg_lun_opts_cdrom.attr,
+        &fsg_lun_opts_nofua.attr,
+        NULL,
+};
+
+static struct config_item_type fsg_lun_type = {
+        .ct_item_ops    = &fsg_lun_item_ops,
+        .ct_attrs       = fsg_lun_attrs,
+        .ct_owner       = THIS_MODULE,
+};
+
+#define MAX_NAME_LEN    40
+
+static struct config_group *fsg_lun_make(struct config_group *group,
+                                         const char *name)
+{
+        struct fsg_lun_opts *opts;
+        struct fsg_opts *fsg_opts;
+        struct fsg_lun_config config;
+        char *num_str;
+        u8 num;
+        int ret;
+
+        num_str = strchr(name, '.');
+        if (!num_str) {
+                pr_err("Unable to locate . in LUN.NUMBER\n");
+                return ERR_PTR(-EINVAL);
+        }
+        num_str++;
+
+        ret = kstrtou8(num_str, 0, &num);
+        if (ret)
+                return ERR_PTR(ret);
+
+        fsg_opts = to_fsg_opts(&group->cg_item);
+        if (num >= FSG_MAX_LUNS)
+                return ERR_PTR(-ENODEV);
+        mutex_lock(&fsg_opts->lock);
+        if (fsg_opts->refcnt || fsg_opts->common->luns[num]) {
+                ret = -EBUSY;
+                goto out;
+        }
+
+        opts = kzalloc(sizeof(*opts), GFP_KERNEL);
+        if (!opts) {
+                ret = -ENOMEM;
+                goto out;
+        }
+
+        memset(&config, 0, sizeof(config));
+        config.removable = true;
+
+
+        ret = fsg_common_create_lun(fsg_opts->common, &config, num, name,
+                                    (const char **)&group->cg_item.ci_name);
+        if (ret) {
+                kfree(opts);
+                goto out;
+        }
+        opts->lun = fsg_opts->common->luns[num];
+        opts->lun_id = num;
+        mutex_unlock(&fsg_opts->lock);
+
+        config_group_init_type_name(&opts->group, name, &fsg_lun_type);
+
+        return &opts->group;
+out:
+        mutex_unlock(&fsg_opts->lock);
+        return ERR_PTR(ret);
+}
+
+static void fsg_lun_drop(struct config_group *group, struct config_item *item)
+{
+        struct fsg_lun_opts *lun_opts;
+        struct fsg_opts *fsg_opts;
+
+        lun_opts = to_fsg_lun_opts(item);
+        fsg_opts = to_fsg_opts(&group->cg_item);
+
+        mutex_lock(&fsg_opts->lock);
+        if (fsg_opts->refcnt) {
+                struct config_item *gadget;
+
+                gadget = group->cg_item.ci_parent->ci_parent;
+                unregister_gadget_item(gadget);
+        }
+
+        fsg_common_remove_lun(lun_opts->lun, fsg_opts->common->sysfs);
+        fsg_opts->common->luns[lun_opts->lun_id] = NULL;
+        lun_opts->lun_id = 0;
+        mutex_unlock(&fsg_opts->lock);
+
+        config_item_put(item);
+}
+
+CONFIGFS_ATTR_STRUCT(fsg_opts);
+CONFIGFS_ATTR_OPS(fsg_opts);
+
+static void fsg_attr_release(struct config_item *item)
+{
+        struct fsg_opts *opts = to_fsg_opts(item);
+
+        usb_put_function_instance(&opts->func_inst);
+}
+
+static struct configfs_item_operations fsg_item_ops = {
+        .release        = fsg_attr_release,
+        .show_attribute = fsg_opts_attr_show,
+        .store_attribute = fsg_opts_attr_store,
+};
+
+static ssize_t fsg_opts_stall_show(struct fsg_opts *opts, char *page)
+{
+        int result;
+
+        mutex_lock(&opts->lock);
+        result = sprintf(page, "%d", opts->common->can_stall);
+        mutex_unlock(&opts->lock);
+
+        return result;
+}
+
+static ssize_t fsg_opts_stall_store(struct fsg_opts *opts, const char *page,
+                                    size_t len)
+{
+        int ret;
+        u8 num;
+
+        mutex_lock(&opts->lock);
+        if (opts->refcnt) {
+                ret = -EBUSY;
+                goto end;
+        }
+        ret = kstrtou8(page, 0, &num);
+        if (ret)
+                goto end;
+
+        opts->common->can_stall = num != 0;
+        ret = len;
+
+end:
+        mutex_unlock(&opts->lock);
+        return ret;
+}
+
+static struct fsg_opts_attribute fsg_opts_stall =
+        __CONFIGFS_ATTR(stall, S_IRUGO | S_IWUSR, fsg_opts_stall_show,
+                        fsg_opts_stall_store);
+
+#ifdef CONFIG_USB_GADGET_DEBUG_FILES
+static ssize_t fsg_opts_num_buffers_show(struct fsg_opts *opts, char *page)
+{
+        int result;
+
+        mutex_lock(&opts->lock);
+        result = sprintf(page, "%d", opts->common->fsg_num_buffers);
+        mutex_unlock(&opts->lock);
+
+        return result;
+}
+
+static ssize_t fsg_opts_num_buffers_store(struct fsg_opts *opts,
+                                          const char *page, size_t len)
+{
+        int ret;
+        u8 num;
+
+        mutex_lock(&opts->lock);
+        if (opts->refcnt) {
+                ret = -EBUSY;
+                goto end;
+        }
+        ret = kstrtou8(page, 0, &num);
+        if (ret)
+                goto end;
+
+        ret = fsg_num_buffers_validate(num);
+        if (ret)
+                goto end;
+
+        fsg_common_set_num_buffers(opts->common, num);
+        ret = len;
+
+end:
+        mutex_unlock(&opts->lock);
+        return ret;
+}
+
+static struct fsg_opts_attribute fsg_opts_num_buffers =
+        __CONFIGFS_ATTR(num_buffers, S_IRUGO | S_IWUSR,
+                        fsg_opts_num_buffers_show,
+                        fsg_opts_num_buffers_store);
+
+#endif
+
+static struct configfs_attribute *fsg_attrs[] = {
+        &fsg_opts_stall.attr,
+#ifdef CONFIG_USB_GADGET_DEBUG_FILES
+        &fsg_opts_num_buffers.attr,
+#endif
+        NULL,
+};
+
+static struct configfs_group_operations fsg_group_ops = {
+        .make_group     = fsg_lun_make,
+        .drop_item      = fsg_lun_drop,
+};
+
+static struct config_item_type fsg_func_type = {
+        .ct_item_ops    = &fsg_item_ops,
+        .ct_group_ops   = &fsg_group_ops,
+        .ct_attrs       = fsg_attrs,
+        .ct_owner       = THIS_MODULE,
+};
+
 static void fsg_free_inst(struct usb_function_instance *fi)
 {
         struct fsg_opts *opts;
@@ -3307,11 +3644,13 @@ static void fsg_free_inst(struct usb_function_instance *fi)
 static struct usb_function_instance *fsg_alloc_inst(void)
 {
         struct fsg_opts *opts;
+        struct fsg_lun_config config;
         int rc;
 
         opts = kzalloc(sizeof(*opts), GFP_KERNEL);
         if (!opts)
                 return ERR_PTR(-ENOMEM);
+        mutex_init(&opts->lock);
         opts->func_inst.free_func_inst = fsg_free_inst;
         opts->common = fsg_common_setup(opts->common, false);
         if (IS_ERR(opts->common)) {
@@ -3329,6 +3668,18 @@ static struct usb_function_instance *fsg_alloc_inst(void)
 
         pr_info(FSG_DRIVER_DESC ", version: " FSG_DRIVER_VERSION "\n");
 
+        memset(&config, 0, sizeof(config));
+        config.removable = true;
+        rc = fsg_common_create_lun(opts->common, &config, 0, "lun.0",
+                        (const char **)&opts->func_inst.group.cg_item.ci_name);
+        opts->lun0.lun = opts->common->luns[0];
+        opts->lun0.lun_id = 0;
+        config_group_init_type_name(&opts->lun0.group, "lun.0", &fsg_lun_type);
+        opts->default_groups[0] = &opts->lun0.group;
+        opts->func_inst.group.default_groups = opts->default_groups;
+
+        config_group_init_type_name(&opts->func_inst.group, "", &fsg_func_type);
+
         return &opts->func_inst;
 
 release_luns:
@@ -3341,8 +3692,14 @@ release_opts:
 static void fsg_free(struct usb_function *f)
 {
         struct fsg_dev *fsg;
+        struct fsg_opts *opts;
 
         fsg = container_of(f, struct fsg_dev, function);
+        opts = container_of(f->fi, struct fsg_opts, func_inst);
+
+        mutex_lock(&opts->lock);
+        opts->refcnt--;
+        mutex_unlock(&opts->lock);
 
         kfree(fsg);
 }
@@ -3357,6 +3714,9 @@ static struct usb_function *fsg_alloc(struct usb_function_instance *fi)
         if (unlikely(!fsg))
                 return ERR_PTR(-ENOMEM);
 
+        mutex_lock(&opts->lock);
+        opts->refcnt++;
+        mutex_unlock(&opts->lock);
         fsg->function.name      = FSG_DRIVER_DESC;
         fsg->function.bind      = fsg_bind;
         fsg->function.unbind    = fsg_unbind;
diff --git a/drivers/usb/gadget/f_mass_storage.h b/drivers/usb/gadget/f_mass_storage.h
index b53cf8c9189e..7d421d2ac3c9 100644
--- a/drivers/usb/gadget/f_mass_storage.h
+++ b/drivers/usb/gadget/f_mass_storage.h
@@ -71,10 +71,27 @@ struct fsg_operations {
         int (*thread_exits)(struct fsg_common *common);
 };
 
+struct fsg_lun_opts {
+        struct config_group group;
+        struct fsg_lun *lun;
+        int lun_id;
+};
+
 struct fsg_opts {
         struct fsg_common *common;
         struct usb_function_instance func_inst;
+        struct fsg_lun_opts lun0;
+        struct config_group *default_groups[2];
         bool no_configfs; /* for legacy gadgets */
+
+        /*
+         * Read/write access to configfs attributes is handled by configfs.
+         *
+         * This is to protect the data from concurrent access by read/write
+         * and create symlink/remove symlink.
+         */
+        struct mutex                    lock;
+        int                             refcnt;
 };
 
 struct fsg_lun_config {