2 * Copyright (c) 2017, NVIDIA CORPORATION. All rights reserved.
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
9 #ifndef __MAILBOX_CONTROLLER_H
10 #define __MAILBOX_CONTROLLER_H
13 #include <linux/types.h>
14 #include <linux/hrtimer.h>
15 #include <linux/device.h>
16 #include <linux/completion.h>
21 * struct mbox_chan_ops - methods to control mailbox channels
22 * @send_data: The API asks the MBOX controller driver, in atomic
23 * context try to transmit a message on the bus. Returns 0 if
24 * data is accepted for transmission, -EBUSY while rejecting
25 * if the remote hasn't yet read the last data sent. Actual
26 * transmission of data is reported by the controller via
27 * mbox_chan_txdone (if it has some TX ACK irq). It must not
29 * @startup: Called when a client requests the chan. The controller
30 * could ask clients for additional parameters of communication
31 * to be provided via client's chan_data. This call may
32 * block. After this call the Controller must forward any
33 * data received on the chan by calling mbox_chan_received_data.
34 * The controller may do stuff that need to sleep.
35 * @shutdown: Called when a client relinquishes control of a chan.
36 * This call may block too. The controller must not forward
37 * any received data anymore.
38 * The controller may do stuff that need to sleep.
39 * @last_tx_done: If the controller sets 'txdone_poll', the API calls
40 * this to poll status of last TX. The controller must
41 * give priority to IRQ method over polling and never
42 * set both txdone_poll and txdone_irq. Only in polling
43 * mode 'send_data' is expected to return -EBUSY.
44 * The controller may do stuff that need to sleep/block.
45 * Used only if txdone_poll:=true && txdone_irq:=false
46 * @peek_data: Atomic check for any received data. Return true if controller
47 * has some data to push to the client. False otherwise.
48 * @get_max_txsize: The API aks the queries the MBOX controller driver for
49 * max tx message len and returns it to the client. Returns
50 * negative on failure, max_txlen on success. If the controller
51 * driver does not impose a limit, returns INT_MAX.
53 struct mbox_chan_ops {
54 int (*send_data)(struct mbox_chan *chan, void *data);
55 int (*startup)(struct mbox_chan *chan);
56 void (*shutdown)(struct mbox_chan *chan);
57 bool (*last_tx_done)(struct mbox_chan *chan);
58 bool (*peek_data)(struct mbox_chan *chan);
59 int (*get_max_txsize)(struct mbox_chan *chan);
63 * struct mbox_controller - Controller of a class of communication channels
64 * @dev: Device backing this controller
65 * @ops: Operators that work on each communication chan
66 * @chans: Array of channels
67 * @num_chans: Number of channels in the 'chans' array.
68 * @txdone_irq: Indicates if the controller can report to API when
69 * the last transmitted data was read by the remote.
70 * Eg, if it has some TX ACK irq.
71 * @txdone_poll: If the controller can read but not report the TX
72 * done. Ex, some register shows the TX status but
73 * no interrupt rises. Ignored if 'txdone_irq' is set.
74 * @txpoll_period: If 'txdone_poll' is in effect, the API polls for
75 * last TX's status after these many millisecs
76 * @of_xlate: Controller driver specific mapping of channel via DT
77 * @poll_hrt: API private. hrtimer used to poll for TXDONE on all
79 * @node: API private. To hook into list of controllers.
81 struct mbox_controller {
83 const struct mbox_chan_ops *ops;
84 struct mbox_chan *chans;
88 unsigned txpoll_period;
89 struct mbox_chan *(*of_xlate)(struct mbox_controller *mbox,
90 const struct of_phandle_args *sp);
92 struct hrtimer poll_hrt;
93 struct list_head node;
97 * The length of circular buffer for queuing messages from a client.
98 * 'msg_count' tracks the number of buffered messages while 'msg_free'
99 * is the index where the next message would be buffered.
100 * We shouldn't need it too big because every transfer is interrupt
101 * triggered and if we have lots of data to transfer, the interrupt
102 * latencies are going to be the bottleneck, not the buffer length.
103 * Besides, mbox_send_message could be called from atomic context and
104 * the client could also queue another message from the notifier 'tx_done'
105 * of the last transfer done.
106 * REVISIT: If too many platforms see the "Try increasing MBOX_TX_QUEUE_LEN"
107 * print, it needs to be taken from config option or somesuch.
109 #define MBOX_TX_QUEUE_LEN 20
112 * struct mbox_chan - s/w representation of a communication chan
113 * @mbox: Pointer to the parent/provider of this channel
114 * @txdone_method: Way to detect TXDone chosen by the API
115 * @cl: Pointer to the current owner of this channel
116 * @tx_complete: Transmission completion
117 * @active_req: Currently active request hook
118 * @msg_count: No. of mssg currently queued
119 * @msg_free: Index of next available mssg slot
120 * @msg_data: Hook for data packet
121 * @lock: Serialise access to the channel
122 * @con_priv: Hook for controller driver to attach private data
125 struct mbox_controller *mbox;
126 unsigned txdone_method;
127 struct mbox_client *cl;
128 struct completion tx_complete;
130 unsigned msg_count, msg_free;
131 void *msg_data[MBOX_TX_QUEUE_LEN];
132 spinlock_t lock; /* Serialise access to the channel */
136 int mbox_controller_register(struct mbox_controller *mbox); /* can sleep */
137 void mbox_controller_unregister(struct mbox_controller *mbox); /* can sleep */
138 void mbox_chan_received_data(struct mbox_chan *chan, void *data); /* atomic */
139 void mbox_chan_txdone(struct mbox_chan *chan, int r); /* atomic */
141 #endif /* __MAILBOX_CONTROLLER_H */