summaryrefslogtreecommitdiff
path: root/drivers/mailbox/bcm2835-mailbox.c
blob: 4b13268529f94e6e9648f5b4919ab48b53280fa0 (plain)
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
52
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
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
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
/*
 *  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);
	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);
	ret = !(readl(mbox->regs + MAIL0_STA) & ARM_MS_FULL);
	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)
		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@v3.sk>");
MODULE_DESCRIPTION("BCM2835 mailbox IPC driver");
MODULE_LICENSE("GPL v2");