1/*
2 * This program is free software; you can redistribute it and/or modify
3 * it under the terms of the GNU General Public License version 2 as
4 * published by the Free Software Foundation.
5 */
6
7#ifndef __MAILBOX_CONTROLLER_H
8#define __MAILBOX_CONTROLLER_H
9
10#include <linux/of.h>
11#include <linux/types.h>
12#include <linux/timer.h>
13#include <linux/device.h>
14#include <linux/completion.h>
15
16struct mbox_chan;
17
18/**
19 * struct mbox_chan_ops - methods to control mailbox channels
20 * @send_data:	The API asks the MBOX controller driver, in atomic
21 *		context try to transmit a message on the bus. Returns 0 if
22 *		data is accepted for transmission, -EBUSY while rejecting
23 *		if the remote hasn't yet read the last data sent. Actual
24 *		transmission of data is reported by the controller via
25 *		mbox_chan_txdone (if it has some TX ACK irq). It must not
26 *		sleep.
27 * @startup:	Called when a client requests the chan. The controller
28 *		could ask clients for additional parameters of communication
29 *		to be provided via client's chan_data. This call may
30 *		block. After this call the Controller must forward any
31 *		data received on the chan by calling mbox_chan_received_data.
32 *		The controller may do stuff that need to sleep.
33 * @shutdown:	Called when a client relinquishes control of a chan.
34 *		This call may block too. The controller must not forward
35 *		any received data anymore.
36 *		The controller may do stuff that need to sleep.
37 * @last_tx_done: If the controller sets 'txdone_poll', the API calls
38 *		  this to poll status of last TX. The controller must
39 *		  give priority to IRQ method over polling and never
40 *		  set both txdone_poll and txdone_irq. Only in polling
41 *		  mode 'send_data' is expected to return -EBUSY.
42 *		  The controller may do stuff that need to sleep/block.
43 *		  Used only if txdone_poll:=true && txdone_irq:=false
44 * @peek_data: Atomic check for any received data. Return true if controller
45 *		  has some data to push to the client. False otherwise.
46 */
47struct mbox_chan_ops {
48	int (*send_data)(struct mbox_chan *chan, void *data);
49	int (*startup)(struct mbox_chan *chan);
50	void (*shutdown)(struct mbox_chan *chan);
51	bool (*last_tx_done)(struct mbox_chan *chan);
52	bool (*peek_data)(struct mbox_chan *chan);
53};
54
55/**
56 * struct mbox_controller - Controller of a class of communication channels
57 * @dev:		Device backing this controller
58 * @ops:		Operators that work on each communication chan
59 * @chans:		Array of channels
60 * @num_chans:		Number of channels in the 'chans' array.
61 * @txdone_irq:		Indicates if the controller can report to API when
62 *			the last transmitted data was read by the remote.
63 *			Eg, if it has some TX ACK irq.
64 * @txdone_poll:	If the controller can read but not report the TX
65 *			done. Ex, some register shows the TX status but
66 *			no interrupt rises. Ignored if 'txdone_irq' is set.
67 * @txpoll_period:	If 'txdone_poll' is in effect, the API polls for
68 *			last TX's status after these many millisecs
69 * @of_xlate:		Controller driver specific mapping of channel via DT
70 * @poll:		API private. Used to poll for TXDONE on all channels.
71 * @node:		API private. To hook into list of controllers.
72 */
73struct mbox_controller {
74	struct device *dev;
75	struct mbox_chan_ops *ops;
76	struct mbox_chan *chans;
77	int num_chans;
78	bool txdone_irq;
79	bool txdone_poll;
80	unsigned txpoll_period;
81	struct mbox_chan *(*of_xlate)(struct mbox_controller *mbox,
82				      const struct of_phandle_args *sp);
83	/* Internal to API */
84	struct timer_list poll;
85	struct list_head node;
86};
87
88/*
89 * The length of circular buffer for queuing messages from a client.
90 * 'msg_count' tracks the number of buffered messages while 'msg_free'
91 * is the index where the next message would be buffered.
92 * We shouldn't need it too big because every transfer is interrupt
93 * triggered and if we have lots of data to transfer, the interrupt
94 * latencies are going to be the bottleneck, not the buffer length.
95 * Besides, mbox_send_message could be called from atomic context and
96 * the client could also queue another message from the notifier 'tx_done'
97 * of the last transfer done.
98 * REVISIT: If too many platforms see the "Try increasing MBOX_TX_QUEUE_LEN"
99 * print, it needs to be taken from config option or somesuch.
100 */
101#define MBOX_TX_QUEUE_LEN	20
102
103/**
104 * struct mbox_chan - s/w representation of a communication chan
105 * @mbox:		Pointer to the parent/provider of this channel
106 * @txdone_method:	Way to detect TXDone chosen by the API
107 * @cl:			Pointer to the current owner of this channel
108 * @tx_complete:	Transmission completion
109 * @active_req:		Currently active request hook
110 * @msg_count:		No. of mssg currently queued
111 * @msg_free:		Index of next available mssg slot
112 * @msg_data:		Hook for data packet
113 * @lock:		Serialise access to the channel
114 * @con_priv:		Hook for controller driver to attach private data
115 */
116struct mbox_chan {
117	struct mbox_controller *mbox;
118	unsigned txdone_method;
119	struct mbox_client *cl;
120	struct completion tx_complete;
121	void *active_req;
122	unsigned msg_count, msg_free;
123	void *msg_data[MBOX_TX_QUEUE_LEN];
124	spinlock_t lock; /* Serialise access to the channel */
125	void *con_priv;
126};
127
128int mbox_controller_register(struct mbox_controller *mbox); /* can sleep */
129void mbox_controller_unregister(struct mbox_controller *mbox); /* can sleep */
130void mbox_chan_received_data(struct mbox_chan *chan, void *data); /* atomic */
131void mbox_chan_txdone(struct mbox_chan *chan, int r); /* atomic */
132
133#endif /* __MAILBOX_CONTROLLER_H */
134