1 /* SPDX-License-Identifier: GPL-2.0+ */
2 /*
3  * SSH request transport layer.
4  *
5  * Copyright (C) 2019-2022 Maximilian Luz <luzmaximilian@gmail.com>
6  */
7 
8 #ifndef _SURFACE_AGGREGATOR_SSH_REQUEST_LAYER_H
9 #define _SURFACE_AGGREGATOR_SSH_REQUEST_LAYER_H
10 
11 #include <linux/atomic.h>
12 #include <linux/ktime.h>
13 #include <linux/list.h>
14 #include <linux/spinlock.h>
15 #include <linux/workqueue.h>
16 
17 #include <linux/surface_aggregator/serial_hub.h>
18 #include <linux/surface_aggregator/controller.h>
19 
20 #include "ssh_packet_layer.h"
21 
22 /**
23  * enum ssh_rtl_state_flags - State-flags for &struct ssh_rtl.
24  *
25  * @SSH_RTL_SF_SHUTDOWN_BIT:
26  *	Indicates that the request transport layer has been shut down or is
27  *	being shut down and should not accept any new requests.
28  */
29 enum ssh_rtl_state_flags {
30 	SSH_RTL_SF_SHUTDOWN_BIT,
31 };
32 
33 /**
34  * struct ssh_rtl_ops - Callback operations for request transport layer.
35  * @handle_event: Function called when a SSH event has been received. The
36  *                specified function takes the request layer, received command
37  *                struct, and corresponding payload as arguments. If the event
38  *                has no payload, the payload span is empty (not %NULL).
39  */
40 struct ssh_rtl_ops {
41 	void (*handle_event)(struct ssh_rtl *rtl, const struct ssh_command *cmd,
42 			     const struct ssam_span *data);
43 };
44 
45 /**
46  * struct ssh_rtl - SSH request transport layer.
47  * @ptl:           Underlying packet transport layer.
48  * @state:         State(-flags) of the transport layer.
49  * @queue:         Request submission queue.
50  * @queue.lock:    Lock for modifying the request submission queue.
51  * @queue.head:    List-head of the request submission queue.
52  * @pending:       Set/list of pending requests.
53  * @pending.lock:  Lock for modifying the request set.
54  * @pending.head:  List-head of the pending set/list.
55  * @pending.count: Number of currently pending requests.
56  * @tx:            Transmitter subsystem.
57  * @tx.work:       Transmitter work item.
58  * @rtx_timeout:   Retransmission timeout subsystem.
59  * @rtx_timeout.lock:    Lock for modifying the retransmission timeout reaper.
60  * @rtx_timeout.timeout: Timeout interval for retransmission.
61  * @rtx_timeout.expires: Time specifying when the reaper work is next scheduled.
62  * @rtx_timeout.reaper:  Work performing timeout checks and subsequent actions.
63  * @ops:           Request layer operations.
64  */
65 struct ssh_rtl {
66 	struct ssh_ptl ptl;
67 	unsigned long state;
68 
69 	struct {
70 		spinlock_t lock;
71 		struct list_head head;
72 	} queue;
73 
74 	struct {
75 		spinlock_t lock;
76 		struct list_head head;
77 		atomic_t count;
78 	} pending;
79 
80 	struct {
81 		struct work_struct work;
82 	} tx;
83 
84 	struct {
85 		spinlock_t lock;
86 		ktime_t timeout;
87 		ktime_t expires;
88 		struct delayed_work reaper;
89 	} rtx_timeout;
90 
91 	struct ssh_rtl_ops ops;
92 };
93 
94 #define rtl_dbg(r, fmt, ...)  ptl_dbg(&(r)->ptl, fmt, ##__VA_ARGS__)
95 #define rtl_info(p, fmt, ...) ptl_info(&(p)->ptl, fmt, ##__VA_ARGS__)
96 #define rtl_warn(r, fmt, ...) ptl_warn(&(r)->ptl, fmt, ##__VA_ARGS__)
97 #define rtl_err(r, fmt, ...)  ptl_err(&(r)->ptl, fmt, ##__VA_ARGS__)
98 #define rtl_dbg_cond(r, fmt, ...) __ssam_prcond(rtl_dbg, r, fmt, ##__VA_ARGS__)
99 
100 #define to_ssh_rtl(ptr, member) \
101 	container_of(ptr, struct ssh_rtl, member)
102 
103 /**
104  * ssh_rtl_get_device() - Get device associated with request transport layer.
105  * @rtl: The request transport layer.
106  *
107  * Return: Returns the device on which the given request transport layer
108  * builds upon.
109  */
110 static inline struct device *ssh_rtl_get_device(struct ssh_rtl *rtl)
111 {
112 	return ssh_ptl_get_device(&rtl->ptl);
113 }
114 
115 /**
116  * ssh_request_rtl() - Get request transport layer associated with request.
117  * @rqst: The request to get the request transport layer reference for.
118  *
119  * Return: Returns the &struct ssh_rtl associated with the given SSH request.
120  */
121 static inline struct ssh_rtl *ssh_request_rtl(struct ssh_request *rqst)
122 {
123 	struct ssh_ptl *ptl;
124 
125 	ptl = READ_ONCE(rqst->packet.ptl);
126 	return likely(ptl) ? to_ssh_rtl(ptl, ptl) : NULL;
127 }
128 
129 int ssh_rtl_submit(struct ssh_rtl *rtl, struct ssh_request *rqst);
130 bool ssh_rtl_cancel(struct ssh_request *rqst, bool pending);
131 
132 int ssh_rtl_init(struct ssh_rtl *rtl, struct serdev_device *serdev,
133 		 const struct ssh_rtl_ops *ops);
134 
135 int ssh_rtl_start(struct ssh_rtl *rtl);
136 int ssh_rtl_flush(struct ssh_rtl *rtl, unsigned long timeout);
137 void ssh_rtl_shutdown(struct ssh_rtl *rtl);
138 void ssh_rtl_destroy(struct ssh_rtl *rtl);
139 
140 int ssh_request_init(struct ssh_request *rqst, enum ssam_request_flags flags,
141 		     const struct ssh_request_ops *ops);
142 
143 #endif /* _SURFACE_AGGREGATOR_SSH_REQUEST_LAYER_H */
144