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/hrtimer.h> 13 #include <linux/device.h> 14 #include <linux/completion.h> 15 16 struct 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 */ 47 struct 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_hrt: API private. hrtimer used to poll for TXDONE on all 71 * channels. 72 * @node: API private. To hook into list of controllers. 73 */ 74 struct mbox_controller { 75 struct device *dev; 76 const struct mbox_chan_ops *ops; 77 struct mbox_chan *chans; 78 int num_chans; 79 bool txdone_irq; 80 bool txdone_poll; 81 unsigned txpoll_period; 82 struct mbox_chan *(*of_xlate)(struct mbox_controller *mbox, 83 const struct of_phandle_args *sp); 84 /* Internal to API */ 85 struct hrtimer poll_hrt; 86 struct list_head node; 87 }; 88 89 /* 90 * The length of circular buffer for queuing messages from a client. 91 * 'msg_count' tracks the number of buffered messages while 'msg_free' 92 * is the index where the next message would be buffered. 93 * We shouldn't need it too big because every transfer is interrupt 94 * triggered and if we have lots of data to transfer, the interrupt 95 * latencies are going to be the bottleneck, not the buffer length. 96 * Besides, mbox_send_message could be called from atomic context and 97 * the client could also queue another message from the notifier 'tx_done' 98 * of the last transfer done. 99 * REVISIT: If too many platforms see the "Try increasing MBOX_TX_QUEUE_LEN" 100 * print, it needs to be taken from config option or somesuch. 101 */ 102 #define MBOX_TX_QUEUE_LEN 20 103 104 /** 105 * struct mbox_chan - s/w representation of a communication chan 106 * @mbox: Pointer to the parent/provider of this channel 107 * @txdone_method: Way to detect TXDone chosen by the API 108 * @cl: Pointer to the current owner of this channel 109 * @tx_complete: Transmission completion 110 * @active_req: Currently active request hook 111 * @msg_count: No. of mssg currently queued 112 * @msg_free: Index of next available mssg slot 113 * @msg_data: Hook for data packet 114 * @lock: Serialise access to the channel 115 * @con_priv: Hook for controller driver to attach private data 116 */ 117 struct mbox_chan { 118 struct mbox_controller *mbox; 119 unsigned txdone_method; 120 struct mbox_client *cl; 121 struct completion tx_complete; 122 void *active_req; 123 unsigned msg_count, msg_free; 124 void *msg_data[MBOX_TX_QUEUE_LEN]; 125 spinlock_t lock; /* Serialise access to the channel */ 126 void *con_priv; 127 }; 128 129 int mbox_controller_register(struct mbox_controller *mbox); /* can sleep */ 130 void mbox_controller_unregister(struct mbox_controller *mbox); /* can sleep */ 131 void mbox_chan_received_data(struct mbox_chan *chan, void *data); /* atomic */ 132 void mbox_chan_txdone(struct mbox_chan *chan, int r); /* atomic */ 133 134 #endif /* __MAILBOX_CONTROLLER_H */ 135