[PATCH 02/10] mailbox: Enable BCM2835 mailbox support

Eric Anholt
2015-03-02T20:54:36Z

From: Lubomir Rintel <lkundrak@v3.sk>

Implement BCM2835 mailbox support as a device registered with the
general purpose mailbox framework. Implementation based on commits by
Lubomir Rintel [1], Suman Anna and Jassi Brar [2] on which to base the
implementation.

[1] http://lists.infradead.org/pipermail/linux-rpi-kernel/2013-April/000528.html
[2] http://lists.infradead.org/pipermail/linux-rpi-kernel/2013-May/000546.html

v2: Squashed Craig's work for review, carried over to new version of
Mailbox framework (changes by Lubomir)

v3: Fix multi-line comment style. Refer to the documentation by
filename. Only declare one MODULE_AUTHOR. Alphabetize includes.
Drop some excessive dev_dbg()s (changes by anholt).

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Craig McGeachie <slapdau@yahoo.com.au>
Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Jassi Brar <jassisinghbrar@gmail.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Jassi Brar <jassisinghbrar@gmail.com>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: linux-rpi-kernel@lists.infradead.org
Cc: linux-arm-kernel@lists.infradead.org
---
drivers/mailbox/Kconfig | 8 ++
drivers/mailbox/Makefile | 2 +
drivers/mailbox/bcm2835-mailbox.c | 284 ++++++++++++++++++++++++++++++++++++++
3 files changed, 294 insertions(+)
create mode 100644 drivers/mailbox/bcm2835-mailbox.c

diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
index 84325f2..2873a03 100644
--- a/drivers/mailbox/Kconfig
+++ b/drivers/mailbox/Kconfig
@@ -51,4 +51,12 @@ 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
+ help
+ 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.
endif
diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
index 2e79231..7feb8da 100644
--- a/drivers/mailbox/Makefile
+++ b/drivers/mailbox/Makefile
@@ -9,3 +9,5 @@ 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
diff --git a/drivers/mailbox/bcm2835-mailbox.c b/drivers/mailbox/bcm2835-mailbox.c
new file mode 100644
index 0000000..604beb7
--- /dev/null
+++ b/drivers/mailbox/bcm2835-mailbox.c
@@ -0,0 +1,284 @@
+/*
+ * Copyright (C) 2010 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://github.com/raspberrypi/
+ * linux.git
+ * - drivers/mailbox/bcm2835-ipc.c by Lubomir Rintel at
+ * https://github.com/hackerspace/rpi-linux/blob/lr-raspberry-pi/drivers/
+ * mailbox/bcm2835-ipc.c
+ * - documentation available on the following web site:
+ * https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface
+ */
+
+#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)
+
+#define MBOX_CHAN_COUNT 16
+
+/* Status register: FIFO state. */
+#define ARM_MS_FULL 0x80000000
+#define ARM_MS_EMPTY 0x40000000
+
+/* Configuration register: Enable interrupts. */
+#define ARM_MC_IHAVEDATAIRQEN 0x00000001
+
+#define MBOX_MSG(chan, data28) (((data28) & ~0xf) | ((chan) & 0xf))
+#define MBOX_CHAN(msg) ((msg) & 0xf)
+#define MBOX_DATA28(msg) ((msg) & ~0xf)
+
+struct bcm2835_mbox;
+
+struct bcm2835_channel {
+ struct bcm2835_mbox *mbox;
+ struct mbox_chan *link;
+ u32 chan_num;
+ bool started;
+};
+
+struct bcm2835_mbox {
+ struct platform_device *pdev;
+ struct device *dev;
+ void __iomem *regs;
+ spinlock_t lock;
+ struct bcm2835_channel channel[MBOX_CHAN_COUNT];
+ struct mbox_controller controller;
+};
+
+#define to_channel(link) ((struct bcm2835_channel *)link->con_priv)
+
+static irqreturn_t bcm2835_mbox_irq(int irq, void *dev_id)
+{
+ struct bcm2835_mbox *mbox = (struct bcm2835_mbox *) dev_id;
+ struct device *dev = mbox->dev;
+
+ while (!(readl(mbox->regs + MAIL0_STA) & ARM_MS_EMPTY)) {
+ u32 msg = readl(mbox->regs + MAIL0_RD);
+ unsigned int chan = MBOX_CHAN(msg);
+
+ if (!mbox->channel[chan].started) {
+ dev_err(dev, "Reply on stopped channel %d\n", chan);
+ continue;
+ }
+ dev_dbg(dev, "Reply 0x%08X\n", msg);
+ mbox_chan_received_data(mbox->channel[chan].link,
+ (void *) MBOX_DATA28(msg));
+ }
+ rmb(); /* Finished last mailbox read. */
+ return IRQ_HANDLED;
+}
+
+static int bcm2835_send_data(struct mbox_chan *link, void *data)
+{
+ struct bcm2835_channel *chan = to_channel(link);
+ struct bcm2835_mbox *mbox = chan->mbox;
+ int ret = 0;
+
+ if (!chan->started)
+ return -ENODEV;
+ spin_lock(&mbox->lock);
+ if (readl(mbox->regs + MAIL0_STA) & ARM_MS_FULL) {
+ rmb(); /* Finished last mailbox read. */
+ ret = -EBUSY;
+ goto end;
+ }
+ wmb(); /* About to write to the mail box. */
+ writel(MBOX_MSG(chan->chan_num, (u32) data), mbox->regs + MAIL1_WRT);
+ dev_dbg(mbox->dev, "Request 0x%08X\n", MBOX_MSG(chan->chan_num,
+ (u32) data));
+end:
+ spin_unlock(&mbox->lock);
+ return ret;
+}
+
+static int bcm2835_startup(struct mbox_chan *link)
+{
+ struct bcm2835_channel *chan = to_channel(link);
+
+ chan->started = true;
+ return 0;
+}
+
+static void bcm2835_shutdown(struct mbox_chan *link)
+{
+ struct bcm2835_channel *chan = to_channel(link);
+
+ chan->started = false;
+}
+
+static bool bcm2835_last_tx_done(struct mbox_chan *link)
+{
+ struct bcm2835_channel *chan = to_channel(link);
+ struct bcm2835_mbox *mbox = chan->mbox;
+ bool ret;
+
+ if (!chan->started)
+ return false;
+ spin_lock(&mbox->lock);
+ ret = !(readl(mbox->regs + MAIL0_STA) & ARM_MS_FULL);
+ rmb(); /* Finished last mailbox read. */
+ spin_unlock(&mbox->lock);
+ return ret;
+}
+
+static 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 int request_mailbox_iomem(struct bcm2835_mbox *mbox)
+{
+ struct platform_device *pdev = mbox->pdev;
+ struct resource *iomem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+ dev_dbg(&pdev->dev, "iomem 0x%08X-0x%08X\n", iomem->start, iomem->end);
+ mbox->regs = devm_ioremap_resource(&pdev->dev, iomem);
+ if (IS_ERR(mbox->regs)) {
+ dev_err(&pdev->dev, "Failed to remap mailbox regs\n");
+ return PTR_ERR(mbox->regs);
+ }
+ return 0;
+}
+
+static int request_mailbox_irq(struct bcm2835_mbox *mbox)
+{
+ int ret;
+ struct device *dev = mbox->dev;
+ struct device_node *np = dev->of_node;
+ int irq = irq_of_parse_and_map(np, 0);
+
+ if (irq <= 0) {
+ dev_err(dev, "Can't get IRQ number for mailbox\n");
+ return -ENODEV;
+ }
+ ret = devm_request_irq(dev, irq, bcm2835_mbox_irq, 0, dev_name(dev),
+ mbox);
+ if (ret) {
+ dev_err(dev, "Failed to register a mailbox IRQ handler\n");
+ return -ENODEV;
+ }
+ return 0;
+}
+
+static int bcm2835_mbox_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct bcm2835_mbox *mbox;
+ int i;
+ int ret = 0;
+
+ mbox = devm_kzalloc(dev, sizeof(*mbox), GFP_KERNEL);
+ if (mbox == NULL) {
+ dev_err(dev, "Failed to allocate mailbox memory\n");
+ return -ENOMEM;
+ }
+ platform_set_drvdata(pdev, mbox);
+ mbox->pdev = pdev;
+ mbox->dev = dev;
+ spin_lock_init(&mbox->lock);
+
+ ret = request_mailbox_irq(mbox);
+ if (ret)
+ return ret;
+ ret = request_mailbox_iomem(mbox);
+ if (ret)
+ return ret;
+
+ mbox->controller.txdone_poll = true;
+ mbox->controller.txpoll_period = 5;
+ mbox->controller.ops = &bcm2835_mbox_chan_ops;
+ mbox->controller.dev = dev;
+ mbox->controller.num_chans = MBOX_CHAN_COUNT;
+ mbox->controller.chans = devm_kzalloc(dev,
+ sizeof(struct mbox_chan) * MBOX_CHAN_COUNT,
+ GFP_KERNEL);
+ if (!mbox->controller.chans) {
+ dev_err(dev, "Failed to alloc mbox_chans\n");
+ return -ENOMEM;
+ }
+
+ for (i = 0; i != MBOX_CHAN_COUNT; ++i) {
+ mbox->channel[i].mbox = mbox;
+ mbox->channel[i].link = &mbox->controller.chans[i];
+ mbox->channel[i].chan_num = i;
+ mbox->controller.chans[i].con_priv =
+ (void *)&mbox->channel[i];
+ }
+
+ ret = mbox_controller_register(&mbox->controller);
+ if (ret)
+ return ret;
+
+ /* Enable the interrupt on data reception */
+ writel(ARM_MC_IHAVEDATAIRQEN, mbox->regs + MAIL0_CNF);
+ 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);
+
+ mbox_controller_unregister(&mbox->controller);
+ 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_platform_driver(bcm2835_mbox_driver);
+
+MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
+MODULE_DESCRIPTION("BCM2835 mailbox IPC driver");
+MODULE_LICENSE("GPL v2");
--
2.1.4