Re: [PATCH 1/3] usb: gadget: storage: Add fsg_get_toc helper
From: Sergei Shtylyov
Date: Wed Mar 09 2011 - 08:42:37 EST
Hello.
On 09-03-2011 15:21, Roger Quadros wrote:
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@xxxxxxxxx>
---
drivers/usb/gadget/storage_common.c | 79 +++++++++++++++++++++++++++++++++++
1 files changed, 79 insertions(+), 0 deletions(-)
diff --git a/drivers/usb/gadget/storage_common.c b/drivers/usb/gadget/storage_common.c
index b015561..ffad1d9 100644
--- a/drivers/usb/gadget/storage_common.c
+++ b/drivers/usb/gadget/storage_common.c
@@ -655,6 +655,85 @@ static void store_cdrom_address(u8 *dest, int msf, u32 addr)
}
}
+/*
The kerneldoc comments should start with "/**".
+ * put_toc() - Builds a TOC with required format @format.
The function is called gsg_get_toc, isn't it?
+ * @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)
+{
+ switch (format) {
+ case 0:
+ /* Formatted TOC */
+ memset(buf, 0, 20);
+ buf[1] = (20-2); /* TOC data length */
Parens not needed here. And kernel style assumes putting spacves around
operators.
+ 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 20;
+ break;
+
+ case 2:
+ /* Raw TOC */
+ memset(buf, 0, 37); /* Header + A0, A1& A2 descriptors */
+ buf[1] = 37; /* 4 + 3*11 */
+ buf[2] = 1; /* First complete session */
+ buf[3] = 2; /* Last complete session */
+
+ buf += 4;
+ /* A0 point */
+ buf[0] = 1; /* Session number */
+ buf[1] = 0x16; /* Data track, copying alowed */
+ /* 2 - Track number 0 -> TOC */
+ buf[3] = 0xA0; /* Point A0 */
+ /* 4, 5, 6 - Min, sec, frame is zero */
+ /* 7 - zero */
+ buf[8] = 1; /* Pmin: 1st track number */
+ /* 9 - disc type 0: CD-ROM/DA with 1st track in mode 1 */
+ /* 10 - pframe 0 */
+
+ buf += 11;
+ /* A1 point*/
+ buf[0] = 1; /* Session number */
+ buf[1] = 0x16; /* Data track, copying alowed */
+ /* 2 - Track number 0 -> TOC */
+ buf[3] = 0xA1; /* Point A1 */
+ /* 4, 5, 6 - Min, sec, frame is zero */
+ /* 7, zero */
+ buf[8] = 1; /* Pmin: last track number */
+ /* 9, 10 - pmin and pframe are 0 */
The above code is repetitive -- might be worth factoring out into a function.
+
+ buf += 11;
+ /* A2 point*/
+ buf[0] = 1; /* Session number */
+ buf[1] = 0x16; /* Data track, copying alowed */
+ /* 2 - Track number 0 -> TOC */
+ buf[3] = 0xA2; /* Point A2 */
+ /* 4, 5, 6 - Min, sec, frame is zero */
+ /* 7, 8, 9, 10 - zero, Pmin, Psec, Pframe of Lead out */
+ store_cdrom_address(&buf[7], msf, curlun->num_sectors);
+ return 37;
+ break;
+ default:
+ /* Multi-session, PMA, ATIP, CD-TEXT not supported/required */
+ return -EINVAL;
+ break;
+ }
+}
+
OK, but where this function is called from?
WBR, Sergei
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