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Subject[PATCH v3 1/3] usb: gadget: storage: Add fsg_get_toc helper
Date
fsg_get_toc can be used by both storage gadgets to build a CD-ROM
Table of Contents which can be used as data for READ_TOC command.
Currently fsg_get_toc supports two TOC formats, i.e.
format 0: Formatted TOC and format 2: Raw TOC.

Raw TOC is required for CD-ROM emulation to work with Mac OS-X.

Signed-off-by: Roger Quadros <roger.quadros@nokia.com>
---
drivers/usb/gadget/storage_common.c | 65 +++++++++++++++++++++++++++++++++++
1 files changed, 65 insertions(+), 0 deletions(-)

diff --git a/drivers/usb/gadget/storage_common.c b/drivers/usb/gadget/storage_common.c
index b015561..38fd675 100644
--- a/drivers/usb/gadget/storage_common.c
+++ b/drivers/usb/gadget/storage_common.c
@@ -655,6 +655,71 @@ static void store_cdrom_address(u8 *dest, int msf, u32 addr)
}
}

+/**
+ * fsg_get_toc() - Builds a TOC with required format @format.
+ * @curlun: The LUN for which the TOC has to be built
+ * @msf: Min Sec Frame format or LBA format for address
+ * @format: TOC format code
+ * @buf: The buffer into which the TOC is built
+ *
+ * Builds a Table of Content which can be used as data for READ_TOC command.
+ * The TOC simulates a single session, single track CD-ROM mode 1 disc.
+ *
+ * Returns number of bytes written to @buf, -EINVAL if format not supported.
+ */
+static int fsg_get_toc(struct fsg_lun *curlun, int msf, int format, u8 *buf)
+{
+ int i, len;
+ switch (format) {
+ case 0:
+ /* Formatted TOC */
+ len = 4 + 2*8; /* 4 byte header + 2 descriptors */
+ memset(buf, 0, len);
+ buf[1] = len - 2; /* TOC Length excludes length field */
+ buf[2] = 1; /* First track number */
+ buf[3] = 1; /* Last track number */
+ buf[5] = 0x16; /* Data track, copying allowed */
+ buf[6] = 0x01; /* Only track is number 1 */
+ store_cdrom_address(&buf[8], msf, 0);
+
+ buf[13] = 0x16; /* Lead-out track is data */
+ buf[14] = 0xAA; /* Lead-out track number */
+ store_cdrom_address(&buf[16], msf, curlun->num_sectors);
+ return len;
+ break;
+
+ case 2:
+ /* Raw TOC */
+ len = 4 + 3*11; /* 4 byte header + 3 descriptors */
+ memset(buf, 0, len); /* Header + A0, A1 & A2 descriptors */
+ buf[1] = len - 2; /* TOC Length excludes length field */
+ buf[2] = 1; /* First complete session */
+ buf[3] = 1; /* Last complete session */
+
+ buf += 4;
+ /* fill in A0, A1 and A2 points */
+ for (i = 0; i < 3; i++) {
+ buf[0] = 1; /* Session number */
+ buf[1] = 0x16; /* Data track, copying allowed */
+ /* 2 - Track number 0 -> TOC */
+ buf[3] = 0xA0 + i; /* A0, A1, A2 point */
+ /* 4, 5, 6 - Min, sec, frame is zero */
+ buf[8] = 1; /* Pmin: last track number */
+ buf += 11; /* go to next track descriptor */
+ }
+ buf -= 11; /* go back to A2 descriptor */
+
+ /* For A2, 7, 8, 9, 10 - zero, Pmin, Psec, Pframe of Lead out */
+ store_cdrom_address(&buf[7], msf, curlun->num_sectors);
+ return len;
+ break;
+ default:
+ /* Multi-session, PMA, ATIP, CD-TEXT not supported/required */
+ return -EINVAL;
+ break;
+ }
+}
+

/*-------------------------------------------------------------------------*/

--
1.6.0.4


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