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Diffstat (limited to 'kernel/include/linux/mailbox_controller.h')
| -rw-r--r-- | kernel/include/linux/mailbox_controller.h | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/kernel/include/linux/mailbox_controller.h b/kernel/include/linux/mailbox_controller.h new file mode 100644 index 000000000..d4cf96f07 --- /dev/null +++ b/kernel/include/linux/mailbox_controller.h @@ -0,0 +1,133 @@ +/* + * 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. + */ + +#ifndef __MAILBOX_CONTROLLER_H +#define __MAILBOX_CONTROLLER_H + +#include <linux/of.h> +#include <linux/types.h> +#include <linux/timer.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: API private. Used to poll for TXDONE on all channels. + * @node: API private. To hook into list of controllers. + */ +struct mbox_controller { + struct device *dev; + 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 timer_list poll; + 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 */ + +#endif /* __MAILBOX_CONTROLLER_H */ |