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mailbox: Add RP1 mailbox support
The Raspberry Pi RP1 includes 2 M3 cores running firmware. This driver adds a mailbox communication channel to them via a doorbell and some shared memory. Signed-off-by: Phil Elwell <phil@raspberrypi.com>
This commit is contained in:
Phil Elwell
Dom Cobley
@@ -390,4 +390,13 @@ config RISCV_SBI_MPXY_MBOX
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or HS-mode hypervisor). Say Y here if you want to have this support.
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If unsure say N.
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config MBOX_RP1
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tristate "RP1 Mailbox"
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depends on MFD_RP1
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help
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An implementation of a mailbox interface to the Raspberry Pi RP1 I/O
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interface. Although written as a mailbox driver, the hardware only
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provides an array of 32 doorbells.
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Say Y here if you want to use the RP1 Mailbox.
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endif
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@@ -82,3 +82,5 @@ obj-$(CONFIG_CIX_MBOX) += cix-mailbox.o
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obj-$(CONFIG_BCM74110_MAILBOX) += bcm74110-mailbox.o
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obj-$(CONFIG_RISCV_SBI_MPXY_MBOX) += riscv-sbi-mpxy-mbox.o
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obj-$(CONFIG_MBOX_RP1) += rp1-mailbox.o
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206
drivers/mailbox/rp1-mailbox.c
Normal file
206
drivers/mailbox/rp1-mailbox.c
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@@ -0,0 +1,206 @@
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2023 Raspberry Pi Ltd.
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*
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* Parts of this driver are based on:
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* - bcm2835-mailbox.c
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* Copyright (C) 2010,2015 Broadcom
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* Copyright (C) 2013-2014 Lubomir Rintel
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* Copyright (C) 2013 Craig McGeachie
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*/
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#include <linux/compat.h>
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#include <linux/device.h>
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#include <linux/dma-mapping.h>
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#include <linux/err.h>
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#include <linux/interrupt.h>
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#include <linux/irq.h>
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#include <linux/kernel.h>
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#include <linux/mailbox_controller.h>
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#include <linux/miscdevice.h>
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#include <linux/module.h>
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#include <linux/of_address.h>
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#include <linux/of_irq.h>
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#include <linux/platform_device.h>
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/*
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* RP1's PROC_EVENTS register can generate interrupts on the M3 cores (when
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* enabled). The 32-bit register is treated as 32 events, all of which share a
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* common interrupt. HOST_EVENTS is the same in the reverse direction.
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*/
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#define SYSCFG_PROC_EVENTS 0x00000008
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#define SYSCFG_HOST_EVENTS 0x0000000c
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#define SYSCFG_HOST_EVENT_IRQ_EN 0x00000010
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#define SYSCFG_HOST_EVENT_IRQ 0x00000014
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#define HW_SET_BITS 0x00002000
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#define HW_CLR_BITS 0x00003000
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#define MAX_CHANS 4 /* 32 is the hardware limit */
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struct rp1_mbox {
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void __iomem *regs;
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unsigned int irq;
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struct mbox_controller controller;
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};
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static struct rp1_mbox *rp1_chan_mbox(struct mbox_chan *chan)
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{
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return container_of(chan->mbox, struct rp1_mbox, controller);
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}
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static unsigned int rp1_chan_event(struct mbox_chan *chan)
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{
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return (unsigned int)(uintptr_t)chan->con_priv;
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}
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static irqreturn_t rp1_mbox_irq(int irq, void *dev_id)
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{
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struct rp1_mbox *mbox = dev_id;
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struct mbox_chan *chan;
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unsigned int doorbell;
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unsigned int evs;
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evs = readl(mbox->regs + SYSCFG_HOST_EVENT_IRQ);
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writel(evs, mbox->regs + SYSCFG_HOST_EVENTS + HW_CLR_BITS);
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while (evs) {
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doorbell = __ffs(evs);
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chan = &mbox->controller.chans[doorbell];
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mbox_chan_received_data(chan, NULL);
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evs &= ~(1 << doorbell);
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}
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return IRQ_HANDLED;
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}
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static int rp1_send_data(struct mbox_chan *chan, void *data)
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{
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struct rp1_mbox *mbox = rp1_chan_mbox(chan);
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unsigned int event = rp1_chan_event(chan);
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writel(event, mbox->regs + SYSCFG_PROC_EVENTS + HW_SET_BITS);
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return 0;
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}
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static int rp1_startup(struct mbox_chan *chan)
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{
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struct rp1_mbox *mbox = rp1_chan_mbox(chan);
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unsigned int event = rp1_chan_event(chan);
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writel(event, mbox->regs + SYSCFG_HOST_EVENT_IRQ_EN + HW_SET_BITS);
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return 0;
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}
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static void rp1_shutdown(struct mbox_chan *chan)
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{
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struct rp1_mbox *mbox = rp1_chan_mbox(chan);
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unsigned int event = rp1_chan_event(chan);
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writel(event, mbox->regs + SYSCFG_HOST_EVENT_IRQ_EN + HW_CLR_BITS);
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}
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static bool rp1_last_tx_done(struct mbox_chan *chan)
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{
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struct rp1_mbox *mbox = rp1_chan_mbox(chan);
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unsigned int event = rp1_chan_event(chan);
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unsigned int evs;
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evs = readl(mbox->regs + SYSCFG_HOST_EVENT_IRQ);
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return !(evs & event);
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}
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static const struct mbox_chan_ops rp1_mbox_chan_ops = {
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.send_data = rp1_send_data,
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.startup = rp1_startup,
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.shutdown = rp1_shutdown,
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.last_tx_done = rp1_last_tx_done
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};
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static struct mbox_chan *rp1_mbox_xlate(struct mbox_controller *mbox,
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const struct of_phandle_args *spec)
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{
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struct mbox_chan *chan;
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unsigned int doorbell;
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if (spec->args_count != 1)
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return ERR_PTR(-EINVAL);
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doorbell = spec->args[0];
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if (doorbell >= MAX_CHANS)
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return ERR_PTR(-EINVAL);
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chan = &mbox->chans[doorbell];
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chan->con_priv = (void *)(uintptr_t)(1 << doorbell);
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return chan;
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}
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static int rp1_mbox_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct mbox_chan *chans;
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struct rp1_mbox *mbox;
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int ret = 0;
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mbox = devm_kzalloc(dev, sizeof(*mbox), GFP_KERNEL);
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if (mbox == NULL)
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return -ENOMEM;
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ret = devm_request_irq(dev, platform_get_irq(pdev, 0),
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rp1_mbox_irq, 0, dev_name(dev), mbox);
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if (ret) {
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dev_err(dev, "Failed to register a mailbox IRQ handler: %d\n",
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ret);
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return -ENODEV;
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}
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mbox->regs = devm_platform_ioremap_resource(pdev, 0);
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if (IS_ERR(mbox->regs)) {
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ret = PTR_ERR(mbox->regs);
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return ret;
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}
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chans = devm_kcalloc(dev, MAX_CHANS, sizeof(*chans), GFP_KERNEL);
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if (!chans)
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return -ENOMEM;
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mbox->controller.txdone_poll = true;
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mbox->controller.txpoll_period = 5;
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mbox->controller.ops = &rp1_mbox_chan_ops;
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mbox->controller.of_xlate = &rp1_mbox_xlate;
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mbox->controller.dev = dev;
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mbox->controller.num_chans = MAX_CHANS;
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mbox->controller.chans = chans;
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ret = devm_mbox_controller_register(dev, &mbox->controller);
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if (ret)
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return ret;
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platform_set_drvdata(pdev, mbox);
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return 0;
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}
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static const struct of_device_id rp1_mbox_of_match[] = {
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{ .compatible = "raspberrypi,rp1-mbox", },
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{},
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};
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MODULE_DEVICE_TABLE(of, rp1_mbox_of_match);
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static struct platform_driver rp1_mbox_driver = {
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.driver = {
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.name = "rp1-mbox",
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.of_match_table = rp1_mbox_of_match,
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},
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.probe = rp1_mbox_probe,
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};
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module_platform_driver(rp1_mbox_driver);
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MODULE_AUTHOR("Phil Elwell <phil@raspberrypi.com>");
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MODULE_DESCRIPTION("RP1 mailbox IPC driver");
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MODULE_LICENSE("GPL v2");
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