141 lines
5.7 KiB
C
141 lines
5.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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#ifndef __MAILBOX_CONTROLLER_H
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#define __MAILBOX_CONTROLLER_H
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#include <linux/of.h>
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#include <linux/types.h>
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#include <linux/hrtimer.h>
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#include <linux/device.h>
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#include <linux/completion.h>
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struct mbox_chan;
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/**
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* struct mbox_chan_ops - methods to control mailbox channels
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* @send_data: The API asks the MBOX controller driver, in atomic
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* context try to transmit a message on the bus. Returns 0 if
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* data is accepted for transmission, -EBUSY while rejecting
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* if the remote hasn't yet read the last data sent. Actual
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* transmission of data is reported by the controller via
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* mbox_chan_txdone (if it has some TX ACK irq). It must not
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* sleep.
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* @flush: Called when a client requests transmissions to be blocking but
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* the context doesn't allow sleeping. Typically the controller
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* will implement a busy loop waiting for the data to flush out.
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* @startup: Called when a client requests the chan. The controller
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* could ask clients for additional parameters of communication
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* to be provided via client's chan_data. This call may
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* block. After this call the Controller must forward any
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* data received on the chan by calling mbox_chan_received_data.
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* The controller may do stuff that need to sleep.
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* @shutdown: Called when a client relinquishes control of a chan.
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* This call may block too. The controller must not forward
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* any received data anymore.
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* The controller may do stuff that need to sleep.
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* @last_tx_done: If the controller sets 'txdone_poll', the API calls
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* this to poll status of last TX. The controller must
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* give priority to IRQ method over polling and never
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* set both txdone_poll and txdone_irq. Only in polling
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* mode 'send_data' is expected to return -EBUSY.
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* The controller may do stuff that need to sleep/block.
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* Used only if txdone_poll:=true && txdone_irq:=false
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* @peek_data: Atomic check for any received data. Return true if controller
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* has some data to push to the client. False otherwise.
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*/
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struct mbox_chan_ops {
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int (*send_data)(struct mbox_chan *chan, void *data);
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int (*flush)(struct mbox_chan *chan, unsigned long timeout);
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int (*startup)(struct mbox_chan *chan);
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void (*shutdown)(struct mbox_chan *chan);
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bool (*last_tx_done)(struct mbox_chan *chan);
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bool (*peek_data)(struct mbox_chan *chan);
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};
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/**
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* struct mbox_controller - Controller of a class of communication channels
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* @dev: Device backing this controller
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* @ops: Operators that work on each communication chan
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* @chans: Array of channels
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* @num_chans: Number of channels in the 'chans' array.
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* @txdone_irq: Indicates if the controller can report to API when
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* the last transmitted data was read by the remote.
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* Eg, if it has some TX ACK irq.
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* @txdone_poll: If the controller can read but not report the TX
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* done. Ex, some register shows the TX status but
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* no interrupt rises. Ignored if 'txdone_irq' is set.
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* @txpoll_period: If 'txdone_poll' is in effect, the API polls for
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* last TX's status after these many millisecs
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* @of_xlate: Controller driver specific mapping of channel via DT
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* @poll_hrt: API private. hrtimer used to poll for TXDONE on all
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* channels.
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* @node: API private. To hook into list of controllers.
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*/
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struct mbox_controller {
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struct device *dev;
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const struct mbox_chan_ops *ops;
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struct mbox_chan *chans;
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int num_chans;
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bool txdone_irq;
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bool txdone_poll;
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unsigned txpoll_period;
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struct mbox_chan *(*of_xlate)(struct mbox_controller *mbox,
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const struct of_phandle_args *sp);
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/* Internal to API */
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struct hrtimer poll_hrt;
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spinlock_t poll_hrt_lock;
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struct list_head node;
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};
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/*
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* The length of circular buffer for queuing messages from a client.
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* 'msg_count' tracks the number of buffered messages while 'msg_free'
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* is the index where the next message would be buffered.
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* We shouldn't need it too big because every transfer is interrupt
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* triggered and if we have lots of data to transfer, the interrupt
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* latencies are going to be the bottleneck, not the buffer length.
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* Besides, mbox_send_message could be called from atomic context and
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* the client could also queue another message from the notifier 'tx_done'
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* of the last transfer done.
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* REVISIT: If too many platforms see the "Try increasing MBOX_TX_QUEUE_LEN"
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* print, it needs to be taken from config option or somesuch.
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*/
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#define MBOX_TX_QUEUE_LEN 20
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/**
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* struct mbox_chan - s/w representation of a communication chan
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* @mbox: Pointer to the parent/provider of this channel
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* @txdone_method: Way to detect TXDone chosen by the API
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* @cl: Pointer to the current owner of this channel
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* @tx_complete: Transmission completion
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* @active_req: Currently active request hook
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* @msg_count: No. of mssg currently queued
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* @msg_free: Index of next available mssg slot
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* @msg_data: Hook for data packet
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* @lock: Serialise access to the channel
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* @con_priv: Hook for controller driver to attach private data
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*/
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struct mbox_chan {
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struct mbox_controller *mbox;
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unsigned txdone_method;
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struct mbox_client *cl;
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struct completion tx_complete;
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void *active_req;
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unsigned msg_count, msg_free;
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void *msg_data[MBOX_TX_QUEUE_LEN];
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spinlock_t lock; /* Serialise access to the channel */
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void *con_priv;
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};
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int mbox_controller_register(struct mbox_controller *mbox); /* can sleep */
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void mbox_controller_unregister(struct mbox_controller *mbox); /* can sleep */
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void mbox_chan_received_data(struct mbox_chan *chan, void *data); /* atomic */
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void mbox_chan_txdone(struct mbox_chan *chan, int r); /* atomic */
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int devm_mbox_controller_register(struct device *dev,
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struct mbox_controller *mbox);
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void devm_mbox_controller_unregister(struct device *dev,
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struct mbox_controller *mbox);
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#endif /* __MAILBOX_CONTROLLER_H */
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