libpayload: usbmsc: Factor out usb_msc_force_init() function

We're planning to have a use case with a custom USB device that
implements the USB mass storage protocol on its bulk endpoints, but does
not have the normal MSC class/protocol interface descriptors and does
not support class-specific control requests (Get Max LUN and Bulk-Only
Reset). We'd like to identify/enumerate the device via
usb_generic_create() in our payload but then reuse all the normal MSC
driver code. In order to make that possible, this patch factors a new
usb_msc_force_init() function out of usb_msc_init() which will
initialize an MSC device without checking its descriptors. It also adds
some "quirks" flags that allow devices registered this way to customize
behavior of the MSC stack.

Change-Id: I50392128409cb2a879954f234149a5e3b060a229
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34227
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

1 files changed, 16 insertions, 1 deletions

diff --git a/payloads/libpayload/include/usb/usbmsc.h b/payloads/libpayload/include/usb/usbmsc.h
index f4562a56d5..8786586e51 100644
--- a/payloads/libpayload/include/usb/usbmsc.h
+++ b/payloads/libpayload/include/usb/usbmsc.h
@@ -34,13 +34,24 @@ typedef struct {
 	unsigned int numblocks;
 	endpoint_t *bulk_in;
 	endpoint_t *bulk_out;
-	u8 usbdisk_created;
+	u8 quirks		: 7;
+	u8 usbdisk_created	: 1;
 	s8 ready;
 	u8 lun;
 	u8 num_luns;
 	void *data; /* For use by consumers of libpayload. */
 } usbmsc_inst_t;
 
+/* Possible values for quirks field. */
+enum {
+	/* Don't check for LUNs (force assumption that there's only one LUN). */
+	USB_MSC_QUIRK_NO_LUNS	= 1 << 0,
+	/* Never do a BULK_ONLY reset, just continue. This means that the device
+	   cannot recover from phase errors and won't detach automatically for
+	   unrecoverable errors. Do not use unless you have to. */
+	USB_MSC_QUIRK_NO_RESET	= 1 << 1,
+};
+
 /* Possible values for ready field. */
 enum {
 	USB_MSC_DETACHED = -1, /* Disk detached or out to lunch. */
@@ -56,4 +67,8 @@ typedef enum { cbw_direction_data_in = 0x80, cbw_direction_data_out = 0
 int readwrite_blocks_512 (usbdev_t *dev, int start, int n, cbw_direction dir, u8 *buf);
 int readwrite_blocks (usbdev_t *dev, int start, int n, cbw_direction dir, u8 *buf);
 
+/* Force a device to enumerate as MSC, without checking class/protocol types.
+   It must still have a bulk endpoint pair and respond to MSC commands. */
+void usb_msc_force_init (usbdev_t *dev, u32 quirks);
+
 #endif