usbgadget: add support for USB mass storage gadget

This driver is based on the f_mass_storage drivers in Linux v5.11 and
U-Boot v2021.01.

Unlike the U-Boot version, it runs asynchronously without blocking the
bootloader from doing other tasks, like exporting other USB gadgets at
the same time or enabling shell access.

With pollers and workqueues, enabling this would need a large rework
of the code to be completely callback based, whenever the original
Linux code sleeps waiting for events. With the new bthread support,
we can actually sleep and handover control to other bthreads until
there is actual work to do.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.barebox.org/20210622082617.18011-9-a.fatoum@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

3 files changed, 119 insertions, 0 deletions

diff --git a/include/usb/gadget-multi.h b/include/usb/gadget-multi.h
index 482aee11d0..79b24ca4df 100644
--- a/include/usb/gadget-multi.h
+++ b/include/usb/gadget-multi.h
@@ -4,10 +4,12 @@
 #include <usb/fastboot.h>
 #include <usb/dfu.h>
 #include <usb/usbserial.h>
+#include <usb/mass_storage.h>
 
 struct f_multi_opts {
 	struct fastboot_opts fastboot_opts;
 	struct f_dfu_opts dfu_opts;
+	struct f_ums_opts ums_opts;
 	bool create_acm;
 	void (*release)(struct f_multi_opts *opts);
 };
@@ -21,11 +23,13 @@ unsigned usb_multi_count_functions(struct f_multi_opts *opts);
 #define USBGADGET_ACM		(1 << 1)
 #define USBGADGET_DFU		(1 << 2)
 #define USBGADGET_FASTBOOT	(1 << 3)
+#define USBGADGET_MASS_STORAGE	(1 << 4)
 
 struct usbgadget_funcs {
 	int flags;
 	const char *fastboot_opts;
 	const char *dfu_opts;
+	const char *ums_opts;
 };
 
 int usbgadget_register(const struct usbgadget_funcs *funcs);
diff --git a/include/usb/mass_storage.h b/include/usb/mass_storage.h
new file mode 100644
index 0000000000..084b3c8e8f
--- /dev/null
+++ b/include/usb/mass_storage.h
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) 2011 Samsung Electrnoics
+ * Lukasz Majewski <l.majewski@samsung.com>
+ */
+
+#ifndef __USB_MASS_STORAGE_H__
+#define __USB_MASS_STORAGE_H__
+
+#include <usb/composite.h>
+
+/* Wait at maximum 60 seconds for cable connection */
+#define UMS_CABLE_READY_TIMEOUT	60
+
+struct fsg_common;
+
+struct f_ums_opts {
+	struct usb_function_instance func_inst;
+	struct fsg_common *common;
+	struct file_list *files;
+	unsigned int num_sectors;
+	int fd;
+	char name[16];
+};
+
+int usb_ums_register(struct f_ums_opts *);
+
+#endif /* __USB_MASS_STORAGE_H__ */
diff --git a/include/usb/storage.h b/include/usb/storage.h
new file mode 100644
index 0000000000..e0240f8645
--- /dev/null
+++ b/include/usb/storage.h
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef __LINUX_USB_STORAGE_H
+#define __LINUX_USB_STORAGE_H
+
+/*
+ * linux/usb/storage.h
+ *
+ * Copyright Matthew Wilcox for Intel Corp, 2010
+ *
+ * This file contains definitions taken from the
+ * USB Mass Storage Class Specification Overview
+ *
+ * Distributed under the terms of the GNU GPL, version two.
+ */
+
+/* Storage subclass codes */
+
+#define USB_SC_RBC	0x01		/* Typically, flash devices */
+#define USB_SC_8020	0x02		/* CD-ROM */
+#define USB_SC_QIC	0x03		/* QIC-157 Tapes */
+#define USB_SC_UFI	0x04		/* Floppy */
+#define USB_SC_8070	0x05		/* Removable media */
+#define USB_SC_SCSI	0x06		/* Transparent */
+#define USB_SC_LOCKABLE	0x07		/* Password-protected */
+
+#define USB_SC_ISD200	0xf0		/* ISD200 ATA */
+#define USB_SC_CYP_ATACB	0xf1	/* Cypress ATACB */
+#define USB_SC_DEVICE	0xff		/* Use device's value */
+
+/* Storage protocol codes */
+
+#define USB_PR_CBI	0x00		/* Control/Bulk/Interrupt */
+#define USB_PR_CB	0x01		/* Control/Bulk w/o interrupt */
+#define USB_PR_BULK	0x50		/* bulk only */
+#define USB_PR_UAS	0x62		/* USB Attached SCSI */
+
+#define USB_PR_USBAT	0x80		/* SCM-ATAPI bridge */
+#define USB_PR_EUSB_SDDR09	0x81	/* SCM-SCSI bridge for SDDR-09 */
+#define USB_PR_SDDR55	0x82		/* SDDR-55 (made up) */
+#define USB_PR_DPCM_USB	0xf0		/* Combination CB/SDDR09 */
+#define USB_PR_FREECOM	0xf1		/* Freecom */
+#define USB_PR_DATAFAB	0xf2		/* Datafab chipsets */
+#define USB_PR_JUMPSHOT	0xf3		/* Lexar Jumpshot */
+#define USB_PR_ALAUDA	0xf4		/* Alauda chipsets */
+#define USB_PR_KARMA	0xf5		/* Rio Karma */
+
+#define USB_PR_DEVICE	0xff		/* Use device's value */
+
+/*
+ * Bulk only data structures
+ */
+
+/* command block wrapper */
+struct bulk_cb_wrap {
+	__le32	Signature;		/* contains 'USBC' */
+	__u32	Tag;			/* unique per command id */
+	__le32	DataTransferLength;	/* size of data */
+	__u8	Flags;			/* direction in bit 0 */
+	__u8	Lun;			/* LUN normally 0 */
+	__u8	Length;			/* length of the CDB */
+	__u8	CDB[16];		/* max command */
+};
+
+#define US_BULK_CB_WRAP_LEN	31
+#define US_BULK_CB_SIGN		0x43425355	/* spells out 'USBC' */
+#define US_BULK_FLAG_IN		(1 << 7)
+#define US_BULK_FLAG_OUT	0
+
+/* command status wrapper */
+struct bulk_cs_wrap {
+	__le32	Signature;	/* contains 'USBS' */
+	__u32	Tag;		/* same as original command */
+	__le32	Residue;	/* amount not transferred */
+	__u8	Status;		/* see below */
+};
+
+#define US_BULK_CS_WRAP_LEN	13
+#define US_BULK_CS_SIGN		0x53425355      /* spells out 'USBS' */
+#define US_BULK_STAT_OK		0
+#define US_BULK_STAT_FAIL	1
+#define US_BULK_STAT_PHASE	2
+
+/* bulk-only class specific requests */
+#define US_BULK_RESET_REQUEST   0xff
+#define US_BULK_GET_MAX_LUN     0xfe
+
+#endif