From da1660d32ffdc084879b55da0580e5bef9c23907 Mon Sep 17 00:00:00 2001 From: Suman Anna Date: Thu, 12 Jun 2014 22:30:34 +0530 Subject: mailbox: rename pl320-ipc specific mailbox.h The patch 30058677 "ARM / highbank: add support for pl320 IPC" added a pl320 IPC specific header file as a generic mailbox.h. This file has been renamed appropriately to allow the introduction of the generic mailbox API framework. Acked-by: Mark Langsdorf Cc: Rafael J. Wysocki Signed-off-by: Suman Anna Reviewed-by: Mark Brown Acked-by: Arnd Bergmann (cherry picked from commit f2fc42b6ac31f4d808da7a9da460dd433a71e976) Signed-off-by: Mark Brown Conflicts: arch/arm/mach-highbank/highbank.c --- arch/arm/mach-highbank/highbank.c | 1 + drivers/cpufreq/highbank-cpufreq.c | 2 +- drivers/mailbox/pl320-ipc.c | 2 +- include/linux/mailbox.h | 17 ----------------- include/linux/pl320-ipc.h | 17 +++++++++++++++++ 5 files changed, 20 insertions(+), 19 deletions(-) delete mode 100644 include/linux/mailbox.h create mode 100644 include/linux/pl320-ipc.h diff --git a/arch/arm/mach-highbank/highbank.c b/arch/arm/mach-highbank/highbank.c index e7df2dd43a40..eec13a1fbb25 100644 --- a/arch/arm/mach-highbank/highbank.c +++ b/arch/arm/mach-highbank/highbank.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include #include diff --git a/drivers/cpufreq/highbank-cpufreq.c b/drivers/cpufreq/highbank-cpufreq.c index b61b5a3fad64..3118b87a37bc 100644 --- a/drivers/cpufreq/highbank-cpufreq.c +++ b/drivers/cpufreq/highbank-cpufreq.c @@ -19,7 +19,7 @@ #include #include #include -#include +#include #include #define HB_CPUFREQ_CHANGE_NOTE 0x80000001 diff --git a/drivers/mailbox/pl320-ipc.c b/drivers/mailbox/pl320-ipc.c index d873cbae2fbb..f3755e0aa935 100644 --- a/drivers/mailbox/pl320-ipc.c +++ b/drivers/mailbox/pl320-ipc.c @@ -26,7 +26,7 @@ #include #include -#include +#include #define IPCMxSOURCE(m) ((m) * 0x40) #define IPCMxDSET(m) (((m) * 0x40) + 0x004) diff --git a/include/linux/mailbox.h b/include/linux/mailbox.h deleted file mode 100644 index 5161f63ec1c8..000000000000 --- a/include/linux/mailbox.h +++ /dev/null @@ -1,17 +0,0 @@ -/* - * This program is free software; you can redistribute it and/or modify it - * under the terms and conditions of the GNU General Public License, - * version 2, as published by the Free Software Foundation. - * - * This program is distributed in the hope it will be useful, but WITHOUT - * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or - * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for - * more details. - * - * You should have received a copy of the GNU General Public License along with - * this program. If not, see . - */ - -int pl320_ipc_transmit(u32 *data); -int pl320_ipc_register_notifier(struct notifier_block *nb); -int pl320_ipc_unregister_notifier(struct notifier_block *nb); diff --git a/include/linux/pl320-ipc.h b/include/linux/pl320-ipc.h new file mode 100644 index 000000000000..5161f63ec1c8 --- /dev/null +++ b/include/linux/pl320-ipc.h @@ -0,0 +1,17 @@ +/* + * This program is free software; you can redistribute it and/or modify it + * under the terms and conditions of the GNU General Public License, + * version 2, as published by the Free Software Foundation. + * + * This program is distributed in the hope it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License along with + * this program. If not, see . + */ + +int pl320_ipc_transmit(u32 *data); +int pl320_ipc_register_notifier(struct notifier_block *nb); +int pl320_ipc_unregister_notifier(struct notifier_block *nb); -- cgit v1.2.3 From e28a642ae1696c5c8936a18bb82ff15b1ff5d61a Mon Sep 17 00:00:00 2001 From: Jassi Brar Date: Thu, 12 Jun 2014 22:31:19 +0530 Subject: mailbox: Introduce framework for mailbox Introduce common framework for client/protocol drivers and controller drivers of Inter-Processor-Communication (IPC). Client driver developers should have a look at include/linux/mailbox_client.h to understand the part of the API exposed to client drivers. Similarly controller driver developers should have a look at include/linux/mailbox_controller.h Reviewed-by: Mark Brown Signed-off-by: Jassi Brar (cherry picked from commit 2b6d83e2b8b7de82331a6a1dcd64b51020a6031c) Signed-off-by: Mark Brown --- MAINTAINERS | 8 + drivers/mailbox/Makefile | 4 + drivers/mailbox/mailbox.c | 465 +++++++++++++++++++++++++++++++++++++ include/linux/mailbox_client.h | 46 ++++ include/linux/mailbox_controller.h | 133 +++++++++++ 5 files changed, 656 insertions(+) create mode 100644 drivers/mailbox/mailbox.c create mode 100644 include/linux/mailbox_client.h create mode 100644 include/linux/mailbox_controller.h diff --git a/MAINTAINERS b/MAINTAINERS index ad7e322ad17b..d5a14e676330 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -5152,6 +5152,14 @@ S: Maintained F: drivers/net/macvlan.c F: include/linux/if_macvlan.h +MAILBOX API +M: Jassi Brar +L: linux-kernel@vger.kernel.org +S: Maintained +F: drivers/mailbox/ +F: include/linux/mailbox_client.h +F: include/linux/mailbox_controller.h + MAN-PAGES: MANUAL PAGES FOR LINUX -- Sections 2, 3, 4, 5, and 7 M: Michael Kerrisk W: http://www.kernel.org/doc/man-pages diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile index 543ad6a79505..fefef7ebcbec 100644 --- a/drivers/mailbox/Makefile +++ b/drivers/mailbox/Makefile @@ -1 +1,5 @@ +# Generic MAILBOX API + +obj-$(CONFIG_MAILBOX) += mailbox.o + obj-$(CONFIG_PL320_MBOX) += pl320-ipc.o diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c new file mode 100644 index 000000000000..afcb430508ec --- /dev/null +++ b/drivers/mailbox/mailbox.c @@ -0,0 +1,465 @@ +/* + * Mailbox: Common code for Mailbox controllers and users + * + * Copyright (C) 2013-2014 Linaro Ltd. + * Author: Jassi Brar + * + * 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define TXDONE_BY_IRQ BIT(0) /* controller has remote RTR irq */ +#define TXDONE_BY_POLL BIT(1) /* controller can read status of last TX */ +#define TXDONE_BY_ACK BIT(2) /* S/W ACK recevied by Client ticks the TX */ + +static LIST_HEAD(mbox_cons); +static DEFINE_MUTEX(con_mutex); + +static int add_to_rbuf(struct mbox_chan *chan, void *mssg) +{ + int idx; + unsigned long flags; + + spin_lock_irqsave(&chan->lock, flags); + + /* See if there is any space left */ + if (chan->msg_count == MBOX_TX_QUEUE_LEN) { + spin_unlock_irqrestore(&chan->lock, flags); + return -ENOBUFS; + } + + idx = chan->msg_free; + chan->msg_data[idx] = mssg; + chan->msg_count++; + + if (idx == MBOX_TX_QUEUE_LEN - 1) + chan->msg_free = 0; + else + chan->msg_free++; + + spin_unlock_irqrestore(&chan->lock, flags); + + return idx; +} + +static void msg_submit(struct mbox_chan *chan) +{ + unsigned count, idx; + unsigned long flags; + void *data; + int err; + + spin_lock_irqsave(&chan->lock, flags); + + if (!chan->msg_count || chan->active_req) + goto exit; + + count = chan->msg_count; + idx = chan->msg_free; + if (idx >= count) + idx -= count; + else + idx += MBOX_TX_QUEUE_LEN - count; + + data = chan->msg_data[idx]; + + /* Try to submit a message to the MBOX controller */ + err = chan->mbox->ops->send_data(chan, data); + if (!err) { + chan->active_req = data; + chan->msg_count--; + } +exit: + spin_unlock_irqrestore(&chan->lock, flags); +} + +static void tx_tick(struct mbox_chan *chan, int r) +{ + unsigned long flags; + void *mssg; + + spin_lock_irqsave(&chan->lock, flags); + mssg = chan->active_req; + chan->active_req = NULL; + spin_unlock_irqrestore(&chan->lock, flags); + + /* Submit next message */ + msg_submit(chan); + + /* Notify the client */ + if (mssg && chan->cl->tx_done) + chan->cl->tx_done(chan->cl, mssg, r); + + if (chan->cl->tx_block) + complete(&chan->tx_complete); +} + +static void poll_txdone(unsigned long data) +{ + struct mbox_controller *mbox = (struct mbox_controller *)data; + bool txdone, resched = false; + int i; + + for (i = 0; i < mbox->num_chans; i++) { + struct mbox_chan *chan = &mbox->chans[i]; + + if (chan->active_req && chan->cl) { + resched = true; + txdone = chan->mbox->ops->last_tx_done(chan); + if (txdone) + tx_tick(chan, 0); + } + } + + if (resched) + mod_timer(&mbox->poll, jiffies + + msecs_to_jiffies(mbox->txpoll_period)); +} + +/** + * mbox_chan_received_data - A way for controller driver to push data + * received from remote to the upper layer. + * @chan: Pointer to the mailbox channel on which RX happened. + * @mssg: Client specific message typecasted as void * + * + * After startup and before shutdown any data received on the chan + * is passed on to the API via atomic mbox_chan_received_data(). + * The controller should ACK the RX only after this call returns. + */ +void mbox_chan_received_data(struct mbox_chan *chan, void *mssg) +{ + /* No buffering the received data */ + if (chan->cl->rx_callback) + chan->cl->rx_callback(chan->cl, mssg); +} +EXPORT_SYMBOL_GPL(mbox_chan_received_data); + +/** + * mbox_chan_txdone - A way for controller driver to notify the + * framework that the last TX has completed. + * @chan: Pointer to the mailbox chan on which TX happened. + * @r: Status of last TX - OK or ERROR + * + * The controller that has IRQ for TX ACK calls this atomic API + * to tick the TX state machine. It works only if txdone_irq + * is set by the controller. + */ +void mbox_chan_txdone(struct mbox_chan *chan, int r) +{ + if (unlikely(!(chan->txdone_method & TXDONE_BY_IRQ))) { + dev_err(chan->mbox->dev, + "Controller can't run the TX ticker\n"); + return; + } + + tx_tick(chan, r); +} +EXPORT_SYMBOL_GPL(mbox_chan_txdone); + +/** + * mbox_client_txdone - The way for a client to run the TX state machine. + * @chan: Mailbox channel assigned to this client. + * @r: Success status of last transmission. + * + * The client/protocol had received some 'ACK' packet and it notifies + * the API that the last packet was sent successfully. This only works + * if the controller can't sense TX-Done. + */ +void mbox_client_txdone(struct mbox_chan *chan, int r) +{ + if (unlikely(!(chan->txdone_method & TXDONE_BY_ACK))) { + dev_err(chan->mbox->dev, "Client can't run the TX ticker\n"); + return; + } + + tx_tick(chan, r); +} +EXPORT_SYMBOL_GPL(mbox_client_txdone); + +/** + * mbox_client_peek_data - A way for client driver to pull data + * received from remote by the controller. + * @chan: Mailbox channel assigned to this client. + * + * A poke to controller driver for any received data. + * The data is actually passed onto client via the + * mbox_chan_received_data() + * The call can be made from atomic context, so the controller's + * implementation of peek_data() must not sleep. + * + * Return: True, if controller has, and is going to push after this, + * some data. + * False, if controller doesn't have any data to be read. + */ +bool mbox_client_peek_data(struct mbox_chan *chan) +{ + if (chan->mbox->ops->peek_data) + return chan->mbox->ops->peek_data(chan); + + return false; +} +EXPORT_SYMBOL_GPL(mbox_client_peek_data); + +/** + * mbox_send_message - For client to submit a message to be + * sent to the remote. + * @chan: Mailbox channel assigned to this client. + * @mssg: Client specific message typecasted. + * + * For client to submit data to the controller destined for a remote + * processor. If the client had set 'tx_block', the call will return + * either when the remote receives the data or when 'tx_tout' millisecs + * run out. + * In non-blocking mode, the requests are buffered by the API and a + * non-negative token is returned for each queued request. If the request + * is not queued, a negative token is returned. Upon failure or successful + * TX, the API calls 'tx_done' from atomic context, from which the client + * could submit yet another request. + * The pointer to message should be preserved until it is sent + * over the chan, i.e, tx_done() is made. + * This function could be called from atomic context as it simply + * queues the data and returns a token against the request. + * + * Return: Non-negative integer for successful submission (non-blocking mode) + * or transmission over chan (blocking mode). + * Negative value denotes failure. + */ +int mbox_send_message(struct mbox_chan *chan, void *mssg) +{ + int t; + + if (!chan || !chan->cl) + return -EINVAL; + + t = add_to_rbuf(chan, mssg); + if (t < 0) { + dev_err(chan->mbox->dev, "Try increasing MBOX_TX_QUEUE_LEN\n"); + return t; + } + + msg_submit(chan); + + if (chan->txdone_method == TXDONE_BY_POLL) + poll_txdone((unsigned long)chan->mbox); + + if (chan->cl->tx_block && chan->active_req) { + unsigned long wait; + int ret; + + if (!chan->cl->tx_tout) /* wait forever */ + wait = msecs_to_jiffies(3600000); + else + wait = msecs_to_jiffies(chan->cl->tx_tout); + + ret = wait_for_completion_timeout(&chan->tx_complete, wait); + if (ret == 0) { + t = -EIO; + tx_tick(chan, -EIO); + } + } + + return t; +} +EXPORT_SYMBOL_GPL(mbox_send_message); + +/** + * mbox_request_channel - Request a mailbox channel. + * @cl: Identity of the client requesting the channel. + * @index: Index of mailbox specifier in 'mboxes' property. + * + * The Client specifies its requirements and capabilities while asking for + * a mailbox channel. It can't be called from atomic context. + * The channel is exclusively allocated and can't be used by another + * client before the owner calls mbox_free_channel. + * After assignment, any packet received on this channel will be + * handed over to the client via the 'rx_callback'. + * The framework holds reference to the client, so the mbox_client + * structure shouldn't be modified until the mbox_free_channel returns. + * + * Return: Pointer to the channel assigned to the client if successful. + * ERR_PTR for request failure. + */ +struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index) +{ + struct device *dev = cl->dev; + struct mbox_controller *mbox; + struct of_phandle_args spec; + struct mbox_chan *chan; + unsigned long flags; + int ret; + + if (!dev || !dev->of_node) { + pr_debug("%s: No owner device node\n", __func__); + return ERR_PTR(-ENODEV); + } + + mutex_lock(&con_mutex); + + if (of_parse_phandle_with_args(dev->of_node, "mboxes", + "#mbox-cells", index, &spec)) { + dev_dbg(dev, "%s: can't parse \"mboxes\" property\n", __func__); + mutex_unlock(&con_mutex); + return ERR_PTR(-ENODEV); + } + + chan = NULL; + list_for_each_entry(mbox, &mbox_cons, node) + if (mbox->dev->of_node == spec.np) { + chan = mbox->of_xlate(mbox, &spec); + break; + } + + of_node_put(spec.np); + + if (!chan || chan->cl || !try_module_get(mbox->dev->driver->owner)) { + dev_dbg(dev, "%s: mailbox not free\n", __func__); + mutex_unlock(&con_mutex); + return ERR_PTR(-EBUSY); + } + + spin_lock_irqsave(&chan->lock, flags); + chan->msg_free = 0; + chan->msg_count = 0; + chan->active_req = NULL; + chan->cl = cl; + init_completion(&chan->tx_complete); + + if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone) + chan->txdone_method |= TXDONE_BY_ACK; + + spin_unlock_irqrestore(&chan->lock, flags); + + ret = chan->mbox->ops->startup(chan); + if (ret) { + dev_err(dev, "Unable to startup the chan (%d)\n", ret); + mbox_free_channel(chan); + chan = ERR_PTR(ret); + } + + mutex_unlock(&con_mutex); + return chan; +} +EXPORT_SYMBOL_GPL(mbox_request_channel); + +/** + * mbox_free_channel - The client relinquishes control of a mailbox + * channel by this call. + * @chan: The mailbox channel to be freed. + */ +void mbox_free_channel(struct mbox_chan *chan) +{ + unsigned long flags; + + if (!chan || !chan->cl) + return; + + chan->mbox->ops->shutdown(chan); + + /* The queued TX requests are simply aborted, no callbacks are made */ + spin_lock_irqsave(&chan->lock, flags); + chan->cl = NULL; + chan->active_req = NULL; + if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK)) + chan->txdone_method = TXDONE_BY_POLL; + + module_put(chan->mbox->dev->driver->owner); + spin_unlock_irqrestore(&chan->lock, flags); +} +EXPORT_SYMBOL_GPL(mbox_free_channel); + +static struct mbox_chan * +of_mbox_index_xlate(struct mbox_controller *mbox, + const struct of_phandle_args *sp) +{ + int ind = sp->args[0]; + + if (ind >= mbox->num_chans) + return NULL; + + return &mbox->chans[ind]; +} + +/** + * mbox_controller_register - Register the mailbox controller + * @mbox: Pointer to the mailbox controller. + * + * The controller driver registers its communication channels + */ +int mbox_controller_register(struct mbox_controller *mbox) +{ + int i, txdone; + + /* Sanity check */ + if (!mbox || !mbox->dev || !mbox->ops || !mbox->num_chans) + return -EINVAL; + + if (mbox->txdone_irq) + txdone = TXDONE_BY_IRQ; + else if (mbox->txdone_poll) + txdone = TXDONE_BY_POLL; + else /* It has to be ACK then */ + txdone = TXDONE_BY_ACK; + + if (txdone == TXDONE_BY_POLL) { + mbox->poll.function = &poll_txdone; + mbox->poll.data = (unsigned long)mbox; + init_timer(&mbox->poll); + } + + for (i = 0; i < mbox->num_chans; i++) { + struct mbox_chan *chan = &mbox->chans[i]; + + chan->cl = NULL; + chan->mbox = mbox; + chan->txdone_method = txdone; + spin_lock_init(&chan->lock); + } + + if (!mbox->of_xlate) + mbox->of_xlate = of_mbox_index_xlate; + + mutex_lock(&con_mutex); + list_add_tail(&mbox->node, &mbox_cons); + mutex_unlock(&con_mutex); + + return 0; +} +EXPORT_SYMBOL_GPL(mbox_controller_register); + +/** + * mbox_controller_unregister - Unregister the mailbox controller + * @mbox: Pointer to the mailbox controller. + */ +void mbox_controller_unregister(struct mbox_controller *mbox) +{ + int i; + + if (!mbox) + return; + + mutex_lock(&con_mutex); + + list_del(&mbox->node); + + for (i = 0; i < mbox->num_chans; i++) + mbox_free_channel(&mbox->chans[i]); + + if (mbox->txdone_poll) + del_timer_sync(&mbox->poll); + + mutex_unlock(&con_mutex); +} +EXPORT_SYMBOL_GPL(mbox_controller_unregister); diff --git a/include/linux/mailbox_client.h b/include/linux/mailbox_client.h new file mode 100644 index 000000000000..307d9cab2026 --- /dev/null +++ b/include/linux/mailbox_client.h @@ -0,0 +1,46 @@ +/* + * Copyright (C) 2013-2014 Linaro Ltd. + * Author: Jassi Brar + * + * 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_CLIENT_H +#define __MAILBOX_CLIENT_H + +#include +#include + +struct mbox_chan; + +/** + * struct mbox_client - User of a mailbox + * @dev: The client device + * @tx_block: If the mbox_send_message should block until data is + * transmitted. + * @tx_tout: Max block period in ms before TX is assumed failure + * @knows_txdone: If the client could run the TX state machine. Usually + * if the client receives some ACK packet for transmission. + * Unused if the controller already has TX_Done/RTR IRQ. + * @rx_callback: Atomic callback to provide client the data received + * @tx_done: Atomic callback to tell client of data transmission + */ +struct mbox_client { + struct device *dev; + bool tx_block; + unsigned long tx_tout; + bool knows_txdone; + + void (*rx_callback)(struct mbox_client *cl, void *mssg); + void (*tx_done)(struct mbox_client *cl, void *mssg, int r); +}; + +struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index); +int mbox_send_message(struct mbox_chan *chan, void *mssg); +void mbox_client_txdone(struct mbox_chan *chan, int r); /* atomic */ +bool mbox_client_peek_data(struct mbox_chan *chan); /* atomic */ +void mbox_free_channel(struct mbox_chan *chan); /* may sleep */ + +#endif /* __MAILBOX_CLIENT_H */ diff --git a/include/linux/mailbox_controller.h b/include/linux/mailbox_controller.h new file mode 100644 index 000000000000..d4cf96f07cfc --- /dev/null +++ b/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 +#include +#include +#include +#include + +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 */ -- cgit v1.2.3 From f5868ee1cc8b4afed64269d658e8bfe3931ee023 Mon Sep 17 00:00:00 2001 From: Jassi Brar Date: Tue, 22 Jul 2014 20:05:58 +0530 Subject: doc: add documentation for mailbox framework Some explanations with examples of how to write to implement users and providers of the mailbox framework. Signed-off-by: Jassi Brar (cherry picked from commit 15320fbcec69dc3a4f217044ed848e4225397e25) Signed-off-by: Mark Brown --- Documentation/mailbox.txt | 122 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 122 insertions(+) create mode 100644 Documentation/mailbox.txt diff --git a/Documentation/mailbox.txt b/Documentation/mailbox.txt new file mode 100644 index 000000000000..60f43ff629aa --- /dev/null +++ b/Documentation/mailbox.txt @@ -0,0 +1,122 @@ + The Common Mailbox Framework + Jassi Brar + + This document aims to help developers write client and controller +drivers for the API. But before we start, let us note that the +client (especially) and controller drivers are likely going to be +very platform specific because the remote firmware is likely to be +proprietary and implement non-standard protocol. So even if two +platforms employ, say, PL320 controller, the client drivers can't +be shared across them. Even the PL320 driver might need to accommodate +some platform specific quirks. So the API is meant mainly to avoid +similar copies of code written for each platform. Having said that, +nothing prevents the remote f/w to also be Linux based and use the +same api there. However none of that helps us locally because we only +ever deal at client's protocol level. + Some of the choices made during implementation are the result of this +peculiarity of this "common" framework. + + + + Part 1 - Controller Driver (See include/linux/mailbox_controller.h) + + Allocate mbox_controller and the array of mbox_chan. +Populate mbox_chan_ops, except peek_data() all are mandatory. +The controller driver might know a message has been consumed +by the remote by getting an IRQ or polling some hardware flag +or it can never know (the client knows by way of the protocol). +The method in order of preference is IRQ -> Poll -> None, which +the controller driver should set via 'txdone_irq' or 'txdone_poll' +or neither. + + + Part 2 - Client Driver (See include/linux/mailbox_client.h) + + The client might want to operate in blocking mode (synchronously +send a message through before returning) or non-blocking/async mode (submit +a message and a callback function to the API and return immediately). + + +struct demo_client { + struct mbox_client cl; + struct mbox_chan *mbox; + struct completion c; + bool async; + /* ... */ +}; + +/* + * This is the handler for data received from remote. The behaviour is purely + * dependent upon the protocol. This is just an example. + */ +static void message_from_remote(struct mbox_client *cl, void *mssg) +{ + struct demo_client *dc = container_of(mbox_client, + struct demo_client, cl); + if (dc->aysnc) { + if (is_an_ack(mssg)) { + /* An ACK to our last sample sent */ + return; /* Or do something else here */ + } else { /* A new message from remote */ + queue_req(mssg); + } + } else { + /* Remote f/w sends only ACK packets on this channel */ + return; + } +} + +static void sample_sent(struct mbox_client *cl, void *mssg, int r) +{ + struct demo_client *dc = container_of(mbox_client, + struct demo_client, cl); + complete(&dc->c); +} + +static void client_demo(struct platform_device *pdev) +{ + struct demo_client *dc_sync, *dc_async; + /* The controller already knows async_pkt and sync_pkt */ + struct async_pkt ap; + struct sync_pkt sp; + + dc_sync = kzalloc(sizeof(*dc_sync), GFP_KERNEL); + dc_async = kzalloc(sizeof(*dc_async), GFP_KERNEL); + + /* Populate non-blocking mode client */ + dc_async->cl.dev = &pdev->dev; + dc_async->cl.rx_callback = message_from_remote; + dc_async->cl.tx_done = sample_sent; + dc_async->cl.tx_block = false; + dc_async->cl.tx_tout = 0; /* doesn't matter here */ + dc_async->cl.knows_txdone = false; /* depending upon protocol */ + dc_async->async = true; + init_completion(&dc_async->c); + + /* Populate blocking mode client */ + dc_sync->cl.dev = &pdev->dev; + dc_sync->cl.rx_callback = message_from_remote; + dc_sync->cl.tx_done = NULL; /* operate in blocking mode */ + dc_sync->cl.tx_block = true; + dc_sync->cl.tx_tout = 500; /* by half a second */ + dc_sync->cl.knows_txdone = false; /* depending upon protocol */ + dc_sync->async = false; + + /* ASync mailbox is listed second in 'mboxes' property */ + dc_async->mbox = mbox_request_channel(&dc_async->cl, 1); + /* Populate data packet */ + /* ap.xxx = 123; etc */ + /* Send async message to remote */ + mbox_send_message(dc_async->mbox, &ap); + + /* Sync mailbox is listed first in 'mboxes' property */ + dc_sync->mbox = mbox_request_channel(&dc_sync->cl, 0); + /* Populate data packet */ + /* sp.abc = 123; etc */ + /* Send message to remote in blocking mode */ + mbox_send_message(dc_sync->mbox, &sp); + /* At this point 'sp' has been sent */ + + /* Now wait for async chan to be done */ + wait_for_completion(&dc_async->c); +} -- cgit v1.2.3 From c583b1fec06304d6128f02b1bffff27202c66abf Mon Sep 17 00:00:00 2001 From: Jassi Brar Date: Tue, 22 Jul 2014 20:40:04 +0530 Subject: dt: mailbox: add generic bindings Define generic bindings for the framework clients to request mailbox channels. Reviewed-by: Mark Brown Signed-off-by: Jassi Brar (cherry picked from commit 9f3e3cacb2ffdefe28c7cf490bf543e4dcb2770a) Signed-off-by: Mark Brown --- .../devicetree/bindings/mailbox/mailbox.txt | 38 ++++++++++++++++++++++ 1 file changed, 38 insertions(+) create mode 100644 Documentation/devicetree/bindings/mailbox/mailbox.txt diff --git a/Documentation/devicetree/bindings/mailbox/mailbox.txt b/Documentation/devicetree/bindings/mailbox/mailbox.txt new file mode 100644 index 000000000000..1a2cd3d266db --- /dev/null +++ b/Documentation/devicetree/bindings/mailbox/mailbox.txt @@ -0,0 +1,38 @@ +* Generic Mailbox Controller and client driver bindings + +Generic binding to provide a way for Mailbox controller drivers to +assign appropriate mailbox channel to client drivers. + +* Mailbox Controller + +Required property: +- #mbox-cells: Must be at least 1. Number of cells in a mailbox + specifier. + +Example: + mailbox: mailbox { + ... + #mbox-cells = <1>; + }; + + +* Mailbox Client + +Required property: +- mboxes: List of phandle and mailbox channel specifiers. + +Optional property: +- mbox-names: List of identifier strings for each mailbox channel + required by the client. The use of this property + is discouraged in favor of using index in list of + 'mboxes' while requesting a mailbox. Instead the + platforms may define channel indices, in DT headers, + to something legible. + +Example: + pwr_cntrl: power { + ... + mbox-names = "pwr-ctrl", "rpc"; + mboxes = <&mailbox 0 + &mailbox 1>; + }; -- cgit v1.2.3