net: iosm: encode or decode datagram

1) Encode UL packet into datagram.
2) Decode DL datagram and route it to network layer.
3) Supports credit based flow control.
Signed-off-by: M Chetan Kumar <m.chetan.kumar@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wwan/iosm/iosm_ipc_mux_codec.h

+/* SPDX-License-Identifier: GPL-2.0-only
+ *
+ * Copyright (C) 2020-21 Intel Corporation.
+ */
+
+#ifndef IOSM_IPC_MUX_CODEC_H
+#define IOSM_IPC_MUX_CODEC_H
+
+#include "iosm_ipc_mux.h"
+
+/* Queue level size and reporting
+ * >1 is enable, 0 is disable
+ */
+#define MUX_QUEUE_LEVEL 1
+
+/* Size of the buffer for the IP MUX commands. */
+#define MUX_MAX_UL_ACB_BUF_SIZE 256
+
+/* Maximum number of packets in a go per session */
+#define MUX_MAX_UL_DG_ENTRIES 100
+
+/* ADGH: Signature of the Datagram Header. */
+#define MUX_SIG_ADGH 0x48474441
+
+/* CMDH: Signature of the Command Header. */
+#define MUX_SIG_CMDH 0x48444D43
+
+/* QLTH: Signature of the Queue Level Table */
+#define MUX_SIG_QLTH 0x48544C51
+
+/* FCTH: Signature of the Flow Credit Table */
+#define MUX_SIG_FCTH 0x48544346
+
+/* MUX UL session threshold factor */
+#define IPC_MEM_MUX_UL_SESS_FCOFF_THRESHOLD_FACTOR (4)
+
+/* Size of the buffer for the IP MUX Lite data buffer. */
+#define IPC_MEM_MAX_DL_MUX_LITE_BUF_SIZE (2 * 1024)
+
+/* MUX UL session threshold in number of packets */
+#define IPC_MEM_MUX_UL_SESS_FCON_THRESHOLD (64)
+
+/* Default time out for sending IPC session commands like
+ * open session, close session etc
+ * unit : milliseconds
+ */
+#define IPC_MUX_CMD_RUN_DEFAULT_TIMEOUT 1000 /* 1 second */
+
+/* MUX UL flow control lower threshold in bytes */
+#define IPC_MEM_MUX_UL_FLOWCTRL_LOW_B 10240 /* 10KB */
+
+/* MUX UL flow control higher threshold in bytes (5ms worth of data)*/
+#define IPC_MEM_MUX_UL_FLOWCTRL_HIGH_B (110 * 1024)
+
+/**
+ * struct mux_adgh - Aggregated Datagram Header.
+ * @signature:		Signature of the Aggregated Datagram Header(0x48474441)
+ * @length:		Length (in bytes) of the datagram header. This length
+ *			shall include the header size. Min value: 0x10
+ * @if_id:		ID of the interface the datagrams belong to
+ * @opt_ipv4v6:		Indicates IPv4(=0)/IPv6(=1), It is optional if not
+ *			used set it to zero.
+ * @reserved:		Reserved bits. Set to zero.
+ * @service_class:	Service class identifier for the datagram.
+ * @next_count:		Count of the datagrams that shall be following this
+ *			datagrams for this interface. A count of zero means
+ *			the next datagram may not belong to this interface.
+ * @reserved1:		Reserved bytes, Set to zero
+ */
+struct mux_adgh {
+	__le32 signature;
+	__le16 length;
+	u8 if_id;
+	u8 opt_ipv4v6;
+	u8 service_class;
+	u8 next_count;
+	u8 reserved1[6];
+};
+
+/**
+ * struct mux_lite_cmdh - MUX Lite Command Header
+ * @signature:		Signature of the Command Header(0x48444D43)
+ * @cmd_len:		Length (in bytes) of the command. This length shall
+ *			include the header size. Minimum value: 0x10
+ * @if_id:		ID of the interface the commands in the table belong to.
+ * @reserved:		Reserved Set to zero.
+ * @command_type:	Command Enum.
+ * @transaction_id:	4 byte value shall be generated and sent along with a
+ *			command Responses and ACKs shall have the same
+ *			Transaction ID as their commands. It shall be unique to
+ *			the command transaction on the given interface.
+ * @param:		Optional parameters used with the command.
+ */
+struct mux_lite_cmdh {
+	__le32 signature;
+	__le16 cmd_len;
+	u8 if_id;
+	u8 reserved;
+	__le32 command_type;
+	__le32 transaction_id;
+	union mux_cmd_param param;
+};
+
+/**
+ * struct mux_lite_vfl - value field in generic table
+ * @nr_of_bytes:	Number of bytes available to transmit in the queue.
+ */
+struct mux_lite_vfl {
+	u32 nr_of_bytes;
+};
+
+/**
+ * struct ipc_mem_lite_gen_tbl - Generic table format for Queue Level
+ *				 and Flow Credit
+ * @signature:	Signature of the table
+ * @length:	Length of the table
+ * @if_id:	ID of the interface the table belongs to
+ * @vfl_length:	Value field length
+ * @reserved:	Reserved
+ * @vfl:	Value field of variable length
+ */
+struct ipc_mem_lite_gen_tbl {
+	__le32 signature;
+	__le16 length;
+	u8 if_id;
+	u8 vfl_length;
+	u32 reserved[2];
+	struct mux_lite_vfl vfl;
+};
+
+/**
+ * ipc_mux_dl_decode -Route the DL packet through the IP MUX layer
+ *		      depending on Header.
+ * @ipc_mux:	Pointer to MUX data-struct
+ * @skb:	Pointer to ipc_skb.
+ */
+void ipc_mux_dl_decode(struct iosm_mux *ipc_mux, struct sk_buff *skb);
+
+/**
+ * ipc_mux_dl_acb_send_cmds - Respond to the Command blocks.
+ * @ipc_mux:		Pointer to MUX data-struct
+ * @cmd_type:		Command
+ * @if_id:		Session interface id.
+ * @transaction_id:	Command transaction id.
+ * @param:		Pointer to command params.
+ * @res_size:		Response size
+ * @blocking:		True for blocking send
+ * @respond:		If true return transaction ID
+ *
+ * Returns: 0 in success and failure value on error
+ */
+int ipc_mux_dl_acb_send_cmds(struct iosm_mux *ipc_mux, u32 cmd_type, u8 if_id,
+			     u32 transaction_id, union mux_cmd_param *param,
+			     size_t res_size, bool blocking, bool respond);
+
+/**
+ * ipc_mux_netif_tx_flowctrl - Enable/Disable TX flow control on MUX sessions.
+ * @session:	Pointer to mux_session struct
+ * @idx:	Session ID
+ * @on:		true for Enable and false for disable flow control
+ */
+void ipc_mux_netif_tx_flowctrl(struct mux_session *session, int idx, bool on);
+
+/**
+ * ipc_mux_ul_trigger_encode - Route the UL packet through the IP MUX layer
+ *			       for encoding.
+ * @ipc_mux:	Pointer to MUX data-struct
+ * @if_id:	Session ID.
+ * @skb:	Pointer to ipc_skb.
+ *
+ * Returns: 0 if successfully encoded
+ *	    failure value on error
+ *	    -EBUSY if packet has to be retransmitted.
+ */
+int ipc_mux_ul_trigger_encode(struct iosm_mux *ipc_mux, int if_id,
+			      struct sk_buff *skb);
+/**
+ * ipc_mux_ul_data_encode - UL encode function for calling from Tasklet context.
+ * @ipc_mux:	Pointer to MUX data-struct
+ *
+ * Returns: TRUE if any packet of any session is encoded FALSE otherwise.
+ */
+bool ipc_mux_ul_data_encode(struct iosm_mux *ipc_mux);
+
+/**
+ * ipc_mux_ul_encoded_process - Handles the Modem processed UL data by adding
+ *				the SKB to the UL free list.
+ * @ipc_mux:	Pointer to MUX data-struct
+ * @skb:	Pointer to ipc_skb.
+ */
+void ipc_mux_ul_encoded_process(struct iosm_mux *ipc_mux, struct sk_buff *skb);
+
+#endif