bcm2835-mailbox.c 5.89 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51
/*
 *  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)
52
#define MAIL1_STA	(ARM_0_MAIL1 + 0x18)
53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120

/* 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);
	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 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;

	spin_lock(&mbox->lock);
121
	ret = !(readl(mbox->regs + MAIL1_STA) & ARM_MS_FULL);
122 123 124 125 126 127 128 129 130 131 132 133 134 135 136
	spin_unlock(&mbox->lock);
	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)
137
		return ERR_PTR(-EINVAL);
138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216

	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",
		.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");