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Release 4.12 include/linux/mailbox_controller.h

Directory: include/linux
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.



#include <linux/of.h>
#include <linux/types.h>
#include <linux/hrtimer.h>
#include <linux/device.h>
#include <linux/completion.h>

struct mbox_chan;

 * struct mbox_chan_ops - methods to control mailbox channels
 * @send_data:  The API asks the MBOX controller driver, in atomic
 *              context try to transmit a message on the bus. Returns 0 if
 *              data is accepted for transmission, -EBUSY while rejecting
 *              if the remote hasn't yet read the last data sent. Actual
 *              transmission of data is reported by the controller via
 *              mbox_chan_txdone (if it has some TX ACK irq). It must not
 *              sleep.
 * @startup:    Called when a client requests the chan. The controller
 *              could ask clients for additional parameters of communication
 *              to be provided via client's chan_data. This call may
 *              block. After this call the Controller must forward any
 *              data received on the chan by calling mbox_chan_received_data.
 *              The controller may do stuff that need to sleep.
 * @shutdown:   Called when a client relinquishes control of a chan.
 *              This call may block too. The controller must not forward
 *              any received data anymore.
 *              The controller may do stuff that need to sleep.
 * @last_tx_done: If the controller sets 'txdone_poll', the API calls
 *                this to poll status of last TX. The controller must
 *                give priority to IRQ method over polling and never
 *                set both txdone_poll and txdone_irq. Only in polling
 *                mode 'send_data' is expected to return -EBUSY.
 *                The controller may do stuff that need to sleep/block.
 *                Used only if txdone_poll:=true && txdone_irq:=false
 * @peek_data: Atomic check for any received data. Return true if controller
 *                has some data to push to the client. False otherwise.

struct mbox_chan_ops {
int (*send_data)(struct mbox_chan *chan, void *data);
int (*startup)(struct mbox_chan *chan);
void (*shutdown)(struct mbox_chan *chan);
bool (*last_tx_done)(struct mbox_chan *chan);
bool (*peek_data)(struct mbox_chan *chan);

 * struct mbox_controller - Controller of a class of communication channels
 * @dev:                Device backing this controller
 * @ops:                Operators that work on each communication chan
 * @chans:              Array of channels
 * @num_chans:          Number of channels in the 'chans' array.
 * @txdone_irq:         Indicates if the controller can report to API when
 *                      the last transmitted data was read by the remote.
 *                      Eg, if it has some TX ACK irq.
 * @txdone_poll:        If the controller can read but not report the TX
 *                      done. Ex, some register shows the TX status but
 *                      no interrupt rises. Ignored if 'txdone_irq' is set.
 * @txpoll_period:      If 'txdone_poll' is in effect, the API polls for
 *                      last TX's status after these many millisecs
 * @of_xlate:           Controller driver specific mapping of channel via DT
 * @poll_hrt:           API private. hrtimer used to poll for TXDONE on all
 *                      channels.
 * @node:               API private. To hook into list of controllers.

struct mbox_controller {
struct device *dev;
const struct mbox_chan_ops *ops;
struct mbox_chan *chans;
int num_chans;
bool txdone_irq;
bool txdone_poll;
unsigned txpoll_period;
struct mbox_chan *(*of_xlate)(struct mbox_controller *mbox,
				      const struct of_phandle_args *sp);
	/* Internal to API */
struct hrtimer poll_hrt;
struct list_head node;

 * The length of circular buffer for queuing messages from a client.
 * 'msg_count' tracks the number of buffered messages while 'msg_free'
 * is the index where the next message would be buffered.
 * We shouldn't need it too big because every transfer is interrupt
 * triggered and if we have lots of data to transfer, the interrupt
 * latencies are going to be the bottleneck, not the buffer length.
 * Besides, mbox_send_message could be called from atomic context and
 * the client could also queue another message from the notifier 'tx_done'
 * of the last transfer done.
 * REVISIT: If too many platforms see the "Try increasing MBOX_TX_QUEUE_LEN"
 * print, it needs to be taken from config option or somesuch.

#define MBOX_TX_QUEUE_LEN	20

 * struct mbox_chan - s/w representation of a communication chan
 * @mbox:               Pointer to the parent/provider of this channel
 * @txdone_method:      Way to detect TXDone chosen by the API
 * @cl:                 Pointer to the current owner of this channel
 * @tx_complete:        Transmission completion
 * @active_req:         Currently active request hook
 * @msg_count:          No. of mssg currently queued
 * @msg_free:           Index of next available mssg slot
 * @msg_data:           Hook for data packet
 * @lock:               Serialise access to the channel
 * @con_priv:           Hook for controller driver to attach private data

struct mbox_chan {
struct mbox_controller *mbox;
unsigned txdone_method;
struct mbox_client *cl;
struct completion tx_complete;
void *active_req;

unsigned msg_count, msg_free;
void *msg_data[MBOX_TX_QUEUE_LEN];
spinlock_t lock; /* Serialise access to the channel */
void *con_priv;

int mbox_controller_register(struct mbox_controller *mbox); /* can sleep */
void mbox_controller_unregister(struct mbox_controller *mbox); /* can sleep */
void mbox_chan_received_data(struct mbox_chan *chan, void *data); /* atomic */
void mbox_chan_txdone(struct mbox_chan *chan, int r); /* atomic */


Overall Contributors

Jassi Brar25598.08%133.33%
Sudeep Holla41.54%133.33%
Andrew Bresticker10.38%133.33%
Directory: include/linux
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