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Message-ID: <CAJe_ZhfRGs4FsB5yWE=f7Vb8CEg+Sc3y8eCp64-UG4L8NNS3_A@mail.gmail.com>
Date: Wed, 4 Jun 2014 18:34:40 +0530
From: Jassi Brar <jaswinder.singh@...aro.org>
To: lkml <linux-kernel@...r.kernel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Anna, Suman" <s-anna@...com>,
Loic Pallardy <loic.pallardy@...com>,
LeyFoon Tan <lftan.linux@...il.com>,
Craig McGeachie <slapdau@...oo.com.au>,
Courtney Cavin <courtney.cavin@...ymobile.com>,
Rob Herring <robherring2@...il.com>,
Arnd Bergmann <arnd@...db.de>,
Josh Cartwright <joshc@...eaurora.org>,
Linus Walleij <linus.walleij@...aro.org>,
Kumar Gala <galak@...eaurora.org>,
"ks.giri@...sung.com" <ks.giri@...sung.com>,
Patch Tracking <patches@...aro.org>,
Bjorn Andersson <bjorn@...o.se>,
Jassi Brar <jaswinder.singh@...aro.org>
Subject: Re: [PATCHv6 2/3] mailbox: Introduce framework for mailbox
On 3 June 2014 00:01, Jassi Brar <jaswinder.singh@...aro.org> wrote:
> diff --git a/include/linux/mailbox_controller.h b/include/linux/mailbox_controller.h
> new file mode 100644
> index 0000000..49bd64e
> --- /dev/null
> +++ b/include/linux/mailbox_controller.h
> @@ -0,0 +1,121 @@
> +/*
> + * 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>
> +
> +struct mbox_chan;
> +
> +/**
> + * struct mbox_chan_ops - s/w representation of a communication chan
> + * @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
> + * block.
> + * @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.
> + * @shutdown: Called when a client relinquishes control of a chan.
> + * This call may block too. The controller must not forwared
> + * any received data anymore.
> + * @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.
> + * 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 chans
> + * @dev: Device backing this controller
> + * @controller_name: Literal name of the controller.
> + * @ops: Operators that work on each communication chan
> + * @chans: Null terminated array of chans.
> + * @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
> + */
> +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);
> + /*
> + * If the controller supports only TXDONE_BY_POLL,
> + * this timer polls all the links for txdone.
> + */
> + struct timer_list poll;
> + unsigned period;
> + /* Hook to add to the global controller list */
> + struct list_head node;
> +} __aligned(32);
> +
> +/*
> + * 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 transferr 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.
> + * REVIST: 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 {
> + struct mbox_controller *mbox; /* Parent Controller */
> + unsigned txdone_method;
> +
> + /* client */
> + struct mbox_client *cl;
> + struct completion tx_complete;
> +
> + void *active_req;
> + unsigned msg_count, msg_free;
> + void *msg_data[MBOX_TX_QUEUE_LEN];
> + /* Access to the channel */
> + spinlock_t lock;
> +
> + /* Private data for controller */
> + void *con_priv;
> +} __aligned(32);
> +
I forgot to drop the unneeded __aligned attribute. Other than this, I
am keen on knowing what else.
Thanks
Jassi
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