Commit 0bae6af6 authored by Lubomir Rintel's avatar Lubomir Rintel Committed by Jassi Brar

mailbox: Enable BCM2835 mailbox support

This mailbox driver provides a single mailbox channel to write 32-bit
values to the VPU and get a 32-bit response.  The Raspberry Pi
firmware uses this mailbox channel to implement firmware calls, while
Roku 2 (despite being derived from the same firmware tree) doesn't.

The driver was originally submitted by Lubomir, based on the
out-of-tree 2708 mailbox driver.  Eric Anholt fixed it up for
upstreaming, with the major functional change being that it now has no
notion of multiple channels (since that is a firmware-dependent
concept) and instead the raspberrypi-firmware driver will do that
bit-twiddling in its own messages.
[Jassi: made the 'mbox_chan_ops' struct as const and removed a redundant
Signed-off-by: default avatarLubomir Rintel <>
Signed-off-by: default avatarCraig McGeachie <>
Signed-off-by: default avatarEric Anholt <>
Acked-by: default avatarStephen Warren <>
Signed-off-by: default avatarJassi Brar <>
parent d4b5c782
......@@ -61,4 +61,13 @@ config ALTERA_MBOX
An implementation of the Altera Mailbox soft core. It is used
to send message between processors. Say Y here if you want to use the
Altera mailbox support.
config BCM2835_MBOX
tristate "BCM2835 Mailbox"
depends on ARCH_BCM2835
An implementation of the BCM2385 Mailbox. It is used to invoke
the services of the Videocore. Say Y here if you want to use the
BCM2835 Mailbox.
......@@ -11,3 +11,5 @@ obj-$(CONFIG_OMAP2PLUS_MBOX) += omap-mailbox.o
obj-$(CONFIG_PCC) += pcc.o
obj-$(CONFIG_ALTERA_MBOX) += mailbox-altera.o
obj-$(CONFIG_BCM2835_MBOX) += bcm2835-mailbox.o
* Copyright (C) 2010,2015 Broadcom
* Copyright (C) 2013-2014 Lubomir Rintel
* Copyright (C) 2013 Craig McGeachie
* 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.
* This device provides a mechanism for writing to the mailboxes,
* that are shared between the ARM and the VideoCore processor
* Parts of the driver are based on:
* - arch/arm/mach-bcm2708/vcio.c file written by Gray Girling that was
* obtained from branch "rpi-3.6.y" of git://
* linux.git
* - drivers/mailbox/bcm2835-ipc.c by Lubomir Rintel at
* mailbox/bcm2835-ipc.c
* - documentation available on the following web site:
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/mailbox_controller.h>
#include <linux/module.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
/* Mailboxes */
#define ARM_0_MAIL0 0x00
#define ARM_0_MAIL1 0x20
* Mailbox registers. We basically only support mailbox 0 & 1. We
* deliver to the VC in mailbox 1, it delivers to us in mailbox 0. See
* BCM2835-ARM-Peripherals.pdf section 1.3 for an explanation about
* the placement of memory barriers.
#define MAIL0_RD (ARM_0_MAIL0 + 0x00)
#define MAIL0_POL (ARM_0_MAIL0 + 0x10)
#define MAIL0_STA (ARM_0_MAIL0 + 0x18)
#define MAIL0_CNF (ARM_0_MAIL0 + 0x1C)
#define MAIL1_WRT (ARM_0_MAIL1 + 0x00)
/* Status register: FIFO state. */
#define ARM_MS_FULL BIT(31)
#define ARM_MS_EMPTY BIT(30)
/* Configuration register: Enable interrupts. */
struct bcm2835_mbox {
void __iomem *regs;
spinlock_t lock;
struct mbox_controller controller;
static struct bcm2835_mbox *bcm2835_link_mbox(struct mbox_chan *link)
return container_of(link->mbox, struct bcm2835_mbox, controller);
static irqreturn_t bcm2835_mbox_irq(int irq, void *dev_id)
struct bcm2835_mbox *mbox = dev_id;
struct device *dev = mbox->;
struct mbox_chan *link = &mbox->controller.chans[0];
while (!(readl(mbox->regs + MAIL0_STA) & ARM_MS_EMPTY)) {
u32 msg = readl(mbox->regs + MAIL0_RD);
dev_dbg(dev, "Reply 0x%08X\n", msg);
mbox_chan_received_data(link, &msg);
static int bcm2835_send_data(struct mbox_chan *link, void *data)
struct bcm2835_mbox *mbox = bcm2835_link_mbox(link);
u32 msg = *(u32 *)data;
writel(msg, mbox->regs + MAIL1_WRT);
dev_dbg(mbox->, "Request 0x%08X\n", msg);
return 0;
static int bcm2835_startup(struct mbox_chan *link)
struct bcm2835_mbox *mbox = bcm2835_link_mbox(link);
/* Enable the interrupt on data reception */
writel(ARM_MC_IHAVEDATAIRQEN, mbox->regs + MAIL0_CNF);
return 0;
static void bcm2835_shutdown(struct mbox_chan *link)
struct bcm2835_mbox *mbox = bcm2835_link_mbox(link);
writel(0, mbox->regs + MAIL0_CNF);
static bool bcm2835_last_tx_done(struct mbox_chan *link)
struct bcm2835_mbox *mbox = bcm2835_link_mbox(link);
bool ret;
ret = !(readl(mbox->regs + MAIL0_STA) & ARM_MS_FULL);
return ret;
static const struct mbox_chan_ops bcm2835_mbox_chan_ops = {
.send_data = bcm2835_send_data,
.startup = bcm2835_startup,
.shutdown = bcm2835_shutdown,
.last_tx_done = bcm2835_last_tx_done
static struct mbox_chan *bcm2835_mbox_index_xlate(struct mbox_controller *mbox,
const struct of_phandle_args *sp)
if (sp->args_count != 0)
return NULL;
return &mbox->chans[0];
static int bcm2835_mbox_probe(struct platform_device *pdev)
struct device *dev = &pdev->dev;
int ret = 0;
struct resource *iomem;
struct bcm2835_mbox *mbox;
mbox = devm_kzalloc(dev, sizeof(*mbox), GFP_KERNEL);
if (mbox == NULL)
return -ENOMEM;
ret = devm_request_irq(dev, irq_of_parse_and_map(dev->of_node, 0),
bcm2835_mbox_irq, 0, dev_name(dev), mbox);
if (ret) {
dev_err(dev, "Failed to register a mailbox IRQ handler: %d\n",
return -ENODEV;
iomem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
mbox->regs = devm_ioremap_resource(&pdev->dev, iomem);
if (IS_ERR(mbox->regs)) {
ret = PTR_ERR(mbox->regs);
dev_err(&pdev->dev, "Failed to remap mailbox regs: %d\n", ret);
return ret;
mbox->controller.txdone_poll = true;
mbox->controller.txpoll_period = 5;
mbox->controller.ops = &bcm2835_mbox_chan_ops;
mbox->controller.of_xlate = &bcm2835_mbox_index_xlate;
mbox-> = dev;
mbox->controller.num_chans = 1;
mbox->controller.chans = devm_kzalloc(dev,
sizeof(*mbox->controller.chans), GFP_KERNEL);
if (!mbox->controller.chans)
return -ENOMEM;
ret = mbox_controller_register(&mbox->controller);
if (ret)
return ret;
platform_set_drvdata(pdev, mbox);
dev_info(dev, "mailbox enabled\n");
return ret;
static int bcm2835_mbox_remove(struct platform_device *pdev)
struct bcm2835_mbox *mbox = platform_get_drvdata(pdev);
return 0;
static const struct of_device_id bcm2835_mbox_of_match[] = {
{ .compatible = "brcm,bcm2835-mbox", },
MODULE_DEVICE_TABLE(of, bcm2835_mbox_of_match);
static struct platform_driver bcm2835_mbox_driver = {
.driver = {
.name = "bcm2835-mbox",
.owner = THIS_MODULE,
.of_match_table = bcm2835_mbox_of_match,
.probe = bcm2835_mbox_probe,
.remove = bcm2835_mbox_remove,
MODULE_AUTHOR("Lubomir Rintel <>");
MODULE_DESCRIPTION("BCM2835 mailbox IPC driver");
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