[PATCH 2/3 v8] mailbox: Enable BCM2835 mailbox support
Eric Anholt
eric at anholt.net
Tue May 5 13:27:45 PDT 2015
From: Lubomir Rintel <lkundrak at v3.sk>
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.
Signed-off-by: Lubomir Rintel <lkundrak at v3.sk>
Signed-off-by: Craig McGeachie <slapdau at yahoo.com.au>
Signed-off-by: Eric Anholt <eric at anholt.net>
Cc: Jassi Brar <jassisinghbrar at gmail.com>
Acked-by: Stephen Warren <swarren at wwwdotorg.org>
---
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).
v4: Use the new bcm2835_peripheral_read_workaround(), drop the
unnecessary wmb()s, make the messages be a pointer to u32, rather
than u32-cast-as-pointer, fold in small static functions, drop
extra error messages, clean up sizeof() arg for malloc, disable
interrupts on unload (changes by anholt).
v5: Rewrite as a single-channel driver, where the old notion of
channels will now be interpreted by an rpi-specific driver. Minor
style fix. Drop peripheral_read_workaround() since it's been
noted that readl() covers the non-interrupt half of it, and I
found that we would need to resolve read ordering in the interrupt
handler anyway (changes by anholt).
v6: rewrite commit message, only turn on interrupts when a client is
present, drop the started flag, use BIT() macro, update Broadcom
copyright (changes by anholt, from Jassi's review). Drop s-o-b of
Jassi and Suman, who appear to have been accidentally added by
Craig (noted by Lubomir).
v7: Drop the txdone-style check in send_data, since the core will make
sure we're not called until the previous one is done. Fix "mbox"
to be static (changes by anholt, from review by Jassi).
v8: Fix compiler warning from txdone check removal. Add a summary of
anholt's changes to the commit message. Supply our own of_xlate
to insist that 0 mbox-cells are provided. Replace global *mbox
with container_of()s. Drop our driver's extra "struct device
*dev".
drivers/mailbox/Kconfig | 8 ++
drivers/mailbox/Makefile | 2 +
drivers/mailbox/bcm2835-mailbox.c | 217 ++++++++++++++++++++++++++++++++++++++
3 files changed, 227 insertions(+)
create mode 100644 drivers/mailbox/bcm2835-mailbox.c
diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
index 84b0a2d..ab574da 100644
--- a/drivers/mailbox/Kconfig
+++ b/drivers/mailbox/Kconfig
@@ -60,4 +60,12 @@ 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 b18201e..8e6d822 100644
--- a/drivers/mailbox/Makefile
+++ b/drivers/mailbox/Makefile
@@ -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
diff --git a/drivers/mailbox/bcm2835-mailbox.c b/drivers/mailbox/bcm2835-mailbox.c
new file mode 100644
index 0000000..16c3453
--- /dev/null
+++ b/drivers/mailbox/bcm2835-mailbox.c
@@ -0,0 +1,217 @@
+/*
+ * 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://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)
+
+/* Status register: FIFO state. */
+#define ARM_MS_FULL BIT(31)
+#define ARM_MS_EMPTY BIT(30)
+
+/* Configuration register: Enable interrupts. */
+#define ARM_MC_IHAVEDATAIRQEN BIT(0)
+
+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->controller.dev;
+ 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);
+ }
+ return IRQ_HANDLED;
+}
+
+static int bcm2835_send_data(struct mbox_chan *link, void *data)
+{
+ struct bcm2835_mbox *mbox = bcm2835_link_mbox(link);
+ int ret = 0;
+ u32 msg = *(u32 *)data;
+
+ spin_lock(&mbox->lock);
+ writel(msg, mbox->regs + MAIL1_WRT);
+ dev_dbg(mbox->controller.dev, "Request 0x%08X\n", msg);
+ spin_unlock(&mbox->lock);
+ return ret;
+}
+
+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;
+
+ spin_lock(&mbox->lock);
+ ret = !(readl(mbox->regs + MAIL0_STA) & ARM_MS_FULL);
+ 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 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;
+ spin_lock_init(&mbox->lock);
+
+ 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",
+ ret);
+ 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->controller.dev = 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);
+ 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 at v3.sk>");
+MODULE_DESCRIPTION("BCM2835 mailbox IPC driver");
+MODULE_LICENSE("GPL v2");
--
2.1.4
More information about the linux-rpi-kernel
mailing list