1/* SPDX-License-Identifier: GPL-2.0+ */
2/*
3 * SSH packet transport layer.
4 *
5 * Copyright (C) 2019-2022 Maximilian Luz <luzmaximilian@gmail.com>
6 */
7
8#ifndef _SURFACE_AGGREGATOR_SSH_PACKET_LAYER_H
9#define _SURFACE_AGGREGATOR_SSH_PACKET_LAYER_H
10
11#include <linux/atomic.h>
12#include <linux/kfifo.h>
13#include <linux/ktime.h>
14#include <linux/list.h>
15#include <linux/serdev.h>
16#include <linux/spinlock.h>
17#include <linux/types.h>
18#include <linux/wait.h>
19#include <linux/workqueue.h>
20
21#include <linux/surface_aggregator/serial_hub.h>
22#include "ssh_parser.h"
23
24/**
25 * enum ssh_ptl_state_flags - State-flags for &struct ssh_ptl.
26 *
27 * @SSH_PTL_SF_SHUTDOWN_BIT:
28 *	Indicates that the packet transport layer has been shut down or is
29 *	being shut down and should not accept any new packets/data.
30 */
31enum ssh_ptl_state_flags {
32	SSH_PTL_SF_SHUTDOWN_BIT,
33};
34
35/**
36 * struct ssh_ptl_ops - Callback operations for packet transport layer.
37 * @data_received: Function called when a data-packet has been received. Both,
38 *                 the packet layer on which the packet has been received and
39 *                 the packet's payload data are provided to this function.
40 */
41struct ssh_ptl_ops {
42	void (*data_received)(struct ssh_ptl *p, const struct ssam_span *data);
43};
44
45/**
46 * struct ssh_ptl - SSH packet transport layer.
47 * @serdev:        Serial device providing the underlying data transport.
48 * @state:         State(-flags) of the transport layer.
49 * @queue:         Packet submission queue.
50 * @queue.lock:    Lock for modifying the packet submission queue.
51 * @queue.head:    List-head of the packet submission queue.
52 * @pending:       Set/list of pending packets.
53 * @pending.lock:  Lock for modifying the pending set.
54 * @pending.head:  List-head of the pending set/list.
55 * @pending.count: Number of currently pending packets.
56 * @tx:            Transmitter subsystem.
57 * @tx.running:    Flag indicating (desired) transmitter thread state.
58 * @tx.thread:     Transmitter thread.
59 * @tx.thread_cplt_tx:  Completion for transmitter thread waiting on transfer.
60 * @tx.thread_cplt_pkt: Completion for transmitter thread waiting on packets.
61 * @tx.packet_wq:  Waitqueue-head for packet transmit completion.
62 * @rx:            Receiver subsystem.
63 * @rx.thread:     Receiver thread.
64 * @rx.wq:         Waitqueue-head for receiver thread.
65 * @rx.fifo:       Buffer for receiving data/pushing data to receiver thread.
66 * @rx.buf:        Buffer for evaluating data on receiver thread.
67 * @rx.blocked:    List of recent/blocked sequence IDs to detect retransmission.
68 * @rx.blocked.seqs:   Array of blocked sequence IDs.
69 * @rx.blocked.offset: Offset indicating where a new ID should be inserted.
70 * @rtx_timeout:   Retransmission timeout subsystem.
71 * @rtx_timeout.lock:    Lock for modifying the retransmission timeout reaper.
72 * @rtx_timeout.timeout: Timeout interval for retransmission.
73 * @rtx_timeout.expires: Time specifying when the reaper work is next scheduled.
74 * @rtx_timeout.reaper:  Work performing timeout checks and subsequent actions.
75 * @ops:           Packet layer operations.
76 */
77struct ssh_ptl {
78	struct serdev_device *serdev;
79	unsigned long state;
80
81	struct {
82		spinlock_t lock;
83		struct list_head head;
84	} queue;
85
86	struct {
87		spinlock_t lock;
88		struct list_head head;
89		atomic_t count;
90	} pending;
91
92	struct {
93		atomic_t running;
94		struct task_struct *thread;
95		struct completion thread_cplt_tx;
96		struct completion thread_cplt_pkt;
97		struct wait_queue_head packet_wq;
98	} tx;
99
100	struct {
101		struct task_struct *thread;
102		struct wait_queue_head wq;
103		struct kfifo fifo;
104		struct sshp_buf buf;
105
106		struct {
107			u16 seqs[8];
108			u16 offset;
109		} blocked;
110	} rx;
111
112	struct {
113		spinlock_t lock;
114		ktime_t timeout;
115		ktime_t expires;
116		struct delayed_work reaper;
117	} rtx_timeout;
118
119	struct ssh_ptl_ops ops;
120};
121
122#define __ssam_prcond(func, p, fmt, ...)		\
123	do {						\
124		typeof(p) __p = (p);			\
125							\
126		if (__p)				\
127			func(__p, fmt, ##__VA_ARGS__);	\
128	} while (0)
129
130#define ptl_dbg(p, fmt, ...)  dev_dbg(&(p)->serdev->dev, fmt, ##__VA_ARGS__)
131#define ptl_info(p, fmt, ...) dev_info(&(p)->serdev->dev, fmt, ##__VA_ARGS__)
132#define ptl_warn(p, fmt, ...) dev_warn(&(p)->serdev->dev, fmt, ##__VA_ARGS__)
133#define ptl_err(p, fmt, ...)  dev_err(&(p)->serdev->dev, fmt, ##__VA_ARGS__)
134#define ptl_dbg_cond(p, fmt, ...) __ssam_prcond(ptl_dbg, p, fmt, ##__VA_ARGS__)
135
136#define to_ssh_ptl(ptr, member) \
137	container_of(ptr, struct ssh_ptl, member)
138
139int ssh_ptl_init(struct ssh_ptl *ptl, struct serdev_device *serdev,
140		 struct ssh_ptl_ops *ops);
141
142void ssh_ptl_destroy(struct ssh_ptl *ptl);
143
144/**
145 * ssh_ptl_get_device() - Get device associated with packet transport layer.
146 * @ptl: The packet transport layer.
147 *
148 * Return: Returns the device on which the given packet transport layer builds
149 * upon.
150 */
151static inline struct device *ssh_ptl_get_device(struct ssh_ptl *ptl)
152{
153	return ptl->serdev ? &ptl->serdev->dev : NULL;
154}
155
156int ssh_ptl_tx_start(struct ssh_ptl *ptl);
157int ssh_ptl_tx_stop(struct ssh_ptl *ptl);
158int ssh_ptl_rx_start(struct ssh_ptl *ptl);
159int ssh_ptl_rx_stop(struct ssh_ptl *ptl);
160void ssh_ptl_shutdown(struct ssh_ptl *ptl);
161
162int ssh_ptl_submit(struct ssh_ptl *ptl, struct ssh_packet *p);
163void ssh_ptl_cancel(struct ssh_packet *p);
164
165ssize_t ssh_ptl_rx_rcvbuf(struct ssh_ptl *ptl, const u8 *buf, size_t n);
166
167/**
168 * ssh_ptl_tx_wakeup_transfer() - Wake up packet transmitter thread for
169 * transfer.
170 * @ptl: The packet transport layer.
171 *
172 * Wakes up the packet transmitter thread, notifying it that the underlying
173 * transport has more space for data to be transmitted. If the packet
174 * transport layer has been shut down, calls to this function will be ignored.
175 */
176static inline void ssh_ptl_tx_wakeup_transfer(struct ssh_ptl *ptl)
177{
178	if (test_bit(SSH_PTL_SF_SHUTDOWN_BIT, &ptl->state))
179		return;
180
181	complete(&ptl->tx.thread_cplt_tx);
182}
183
184void ssh_packet_init(struct ssh_packet *packet, unsigned long type,
185		     u8 priority, const struct ssh_packet_ops *ops);
186
187int ssh_ctrl_packet_cache_init(void);
188void ssh_ctrl_packet_cache_destroy(void);
189
190#endif /* _SURFACE_AGGREGATOR_SSH_PACKET_LAYER_H */
191