modem_shm: Shared Memory layout for ST-E M7400 driver.

Add data structures defining the channel configuration and the shared
memory layout used for ST-Ericsson's M7400 modem. These data
structures are shared between the Linux host and the M7400 modem.

The data structures contains table of content, channel configuration,
and ring-buffer indexes for read and write pointers.

Signed-off-by: Sjur Brændeland <sjur.brandeland@stericsson.com>

diff --git a/drivers/modem_shm/shm_ipctoc.h b/drivers/modem_shm/shm_ipctoc.h
new file mode 100644 (file)
index 0000000..1a9b072
--- /dev/null
+++ b/drivers/modem_shm/shm_ipctoc.h
@@ -0,0 +1,154 @@
+/*
+ * Copyright (C) ST-Ericsson AB 2012
+ * Author: Sjur Brændeland / sjur.brandeland@stericsson.com
+ * License terms: GNU General Public License (GPL) version 2
+ */
+
+#ifndef SHM_TOC
+#define SHM_TOC
+
+/**
+ * DOC: SHM Shared Memory Layout
+ *
+ * SHM defines a set of structures describing the memory layout used
+ * for the Shared Memory IPC. In short &toc_entry points out &ipc_toc,
+ * which points out the &shm_ipctoc_channel. &shm_ipctoc_channel defines
+ * the channels used to communicate between host and external device (modem).
+ *
+ *  &shm_ipctoc_channel can be used in packet-mode or stream-mode,
+ *  and points out &shm_bufidx holding information about cirular
+ *  buffers, andtheir read/write indices etc.
+ */
+
+struct _shm_offsets {
+       __le32 tx;
+       __le32 rx;
+};
+
+/**
+ * struct shm_ipctoc - Table Of Content definition for IPC.
+ *
+ * @subver:    Sub version of the TOC header.
+ * @version:   Main version of the TOC header.
+ * @magic:     Magic shall always be set to Ascii coded string "TC" (2 bytes)
+ * @channel_offsets: Offset to both rx and tx direction must be set.
+ *                     The array must be terminated by a zero value.
+ *
+ * This struct is stored at the start of the External Shared memory, and
+ * serves as a extended table of contents defining the channel configurations
+ * for the external shared memory protocol between a modem and host.
+ *
+ * This extended table of content (ipctoc) is written to a predefine memory
+ * location and the modem will read this ipctoc during start-up and use this
+ * for setting up the IPC channels and it's buffers.
+ *
+ */
+
+struct shm_ipctoc {
+       __u8 subver;
+       __u8 version;
+       __u8 magic[2];
+       struct _shm_offsets channel_offsets[8];
+};
+
+#define SHM_IPCTOC_MAGIC1 'T'
+#define SHM_IPCTOC_MAGIC2 'C'
+
+/**
+ * struct shm_ipctoc_channel - Channel descriptor for External Shared memory.
+ *
+ * @offset: Relative address to channel data area.
+ * @size: Total size of a SHM channel area partition.
+ * @mode: Mode of channel: Packet mode=1, Stream mode (shm_channel_mode = 2).
+ * @buffers: Number of buffers for the channel.
+ * @ipc: Offset to IPC message location (of type struct shm_bufidx).
+ * @read_bit: GENI/O bit used to indicate update of the read pointer for
+ *     this channel (at offset ipc).
+ * @write_bit: GENI/O bit used to indicate update of the write pointer for
+ *     this channel (at offset ipc).
+ * @alignment: Protocol specific options for the protocol,
+ *     e.g. packet alignment.
+ * @packets: Maximum Number of packets in a buffer (packet mode).
+ * @mtu: Maximum Transfer Unit for packets in a buffer (packet mode).
+ *
+ * This struct defines the channel configuration for a single direction.
+ *
+ * This structure is pointed out by the &shm_toc and is written by
+ * host during start-up and read by modem at firmware boot.
+ *
+ */
+
+struct shm_ipctoc_channel {
+       __le32 offset;
+       __le32 size;
+       __u8 mode;
+/* private: */
+       __u8 unused[3];
+/* public: */
+       __le32 buffers;
+       __le32 ipc;
+       __le16 read_bit;
+       __le16 write_bit;
+       __u8 alignment;
+       __u8 packets;
+       __u16 mtu;
+};
+
+/**
+ * struct shm_bufidx - Indices's for a uni-directional shm channel.
+ *
+ * @read_index: Specify the read index for a channel. This field can
+ *     have value in range of [0.. shm_ipctoc_channel.buffers -1].
+ *     In stream mode - this is the read index in the ringbuffer.
+ *     In packet mode - this index will at any time refer to the next
+ *     buffer available for read.
+ *
+ * @write_index: Specify the write index for a channel.
+ *     This field can have value in range of [0.. buffers -1].
+ *     In stream mode - this is the write index in the ringbuffer.
+ *     In packet mode - this index will at any time refer to the next
+ *     buffer available for write.
+ *
+ * @size: The actual number of bytes for a buffer at each index.
+ *       This array has shm_ipctoc_channel.buffers slots, one for each buffer.
+ *       The size is updated every time data is written to the buffer.
+ *
+ * @state: The state of the channel, 0 - Closed, 1 - Open
+ *
+ *
+ * This structure contains data for the ring-buffer used in packet and stream
+ * mode, for the external shared memory protocol.
+ * Note that the read_buf_index and the write_buf_index
+ * refer to two different channels. So for a ring buffer used to communicate
+ * from modem, the modem will update the write_buf_index while Linux host
+ * will update read_buf_index.
+ */
+struct shm_bufidx {
+       __le32 state;
+       __le32 read_index;
+       __le32 write_index;
+       __le32 size[0];
+};
+
+/**
+ * struct toc_entry - Points out the boot imiages
+ *
+ * @start: Offset counting from start of memory area to the image data.
+ * @size:  Size of the images in bytes.
+ * @flags: Use 0 if no flags are in use.
+ * @entry: Where to jump to start exeuting. Only applicable
+ *             when using SDRAM. Set to 0xffffffff if unused.
+ * @load_addr: Location in SDRAM to move image. Set to 0xffffffff if
+ *             not applicable.
+ * @name: Name of image.
+ */
+struct toc_entry {
+       __le32 start;
+       __le32 size;
+       __le32 flags;
+       __le32 entry_point;
+       __le32 load_addr;
+       char name[12];
+};
+
+#endif