mailbox的controller

mailbox是kernel提供的一种板子上的硬件和soc通过messages queue，interrupt 进行通讯的一个架构。正式版的英文翻译如下：menuconfig MAILBOXbool "Mailbox Hardware Support"help  Mailbox is a framework to control hardware communication between  on-chip processors through queued messages and interrupt driven  signals. Say Y if your platform supports hardware mailboxes.mailbox的实现分为contoller和client。简单的说就是clinet 可以通过controller提供的channle发送信息给conroller因此在drivers/mailbox下实现的都是controller的源码具体到某个厂商的硬件，则描述如下：config ARM_MHU    tristate "ARM MHU Mailbox"    depends on ARM_AMBA    help      Say Y here if you want to build the ARM MHU controller driver.      The controller has 3 mailbox channels, the last of which can be      used in Secure mode only.通过makefile我们知道要实现mailbox的源文件其实只有两个obj-$(CONFIG_MAILBOX)+= mailbox.oobj-$(CONFIG_ARM_MHU)+= arm_mhu.o其中mailbox.c 是kernel提供的framework，arm_mhu.c 则是具体厂商的实现这里直接看arm_mhu.c的probe函数static int mhu_probe(struct amba_device *adev, const struct amba_id *id){int i, err;struct arm_mhu *mhu;struct device *dev = &adev->dev;int mhu_reg[MHU_CHANS] = {MHU_LP_OFFSET, MHU_HP_OFFSET, MHU_SEC_OFFSET};/* Allocate memory for device */mhu = devm_kzalloc(dev, sizeof(*mhu), GFP_KERNEL);if (!mhu)return -ENOMEM;mhu->base = devm_ioremap_resource(dev, &adev->res);if (IS_ERR(mhu->base)) {dev_err(dev, "ioremap failed\n");return PTR_ERR(mhu->base);}//mailbox的channel 表示可以发送信息的寄存器for (i = 0; i < MHU_CHANS; i++) {mhu->chan[i].con_priv = &mhu->mlink[i];mhu->mlink[i].irq = adev->irq[i];mhu->mlink[i].rx_reg = mhu->base + mhu_reg[i];mhu->mlink[i].tx_reg = mhu->mlink[i].rx_reg + TX_REG_OFFSET;}//初始化mbox的结构体mhu->mbox.dev = dev;mhu->mbox.chans = &mhu->chan[0];mhu->mbox.num_chans = MHU_CHANS;//mbox.ops 表示mailbox这个硬件具体的操作，例如发送数据，初始化等mhu->mbox.ops = &mhu_ops;//发送数据采用poll的方式mhu->mbox.txdone_irq = false;mhu->mbox.txdone_poll = true;mhu->mbox.txpoll_period = 1;amba_set_drvdata(adev, mhu);//所有的controller 最终都要通过mbox_controller_register 来注册自己err = mbox_controller_register(&mhu->mbox);if (err) {dev_err(dev, "Failed to register mailboxes %d\n", err);return err;}dev_info(dev, "ARM MHU Mailbox registered\n");return 0;}int mbox_controller_register(struct mbox_controller *mbox){int i, txdone;//下面这四个任何一个为null，就退出注册/* Sanity check */if (!mbox || !mbox->dev || !mbox->ops || !mbox->num_chans)return -EINVAL;//client发送数据是通过poll的方式还是irq的方式，后面针对两种方式有不同的处理方式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;//如果是poll的方式，则注册一个timer，定时查询if (txdone == TXDONE_BY_POLL) {if (!mbox->ops->last_tx_done) {dev_err(mbox->dev, "last_tx_done method is absent\n");return -EINVAL;}hrtimer_init(&mbox->poll_hrt, CLOCK_MONOTONIC,     HRTIMER_MODE_REL);mbox->poll_hrt.function = txdone_hrtimer;}//初始化controller的channel，表示contoller 同时能尽量几路信息的传递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;//所有的mailbox最终都会添加到mbox_cons 这个list中mutex_lock(&con_mutex);list_add_tail(&mbox->node, &mbox_cons);mutex_unlock(&con_mutex);return 0;}