1 /*
2  *  Copyright (C) 2010,2015 Broadcom
3  *  Copyright (C) 2013-2014 Lubomir Rintel
4  *  Copyright (C) 2013 Craig McGeachie
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  *
10  * This device provides a mechanism for writing to the mailboxes,
11  * that are shared between the ARM and the VideoCore processor
12  *
13  * Parts of the driver are based on:
14  *  - arch/arm/mach-bcm2708/vcio.c file written by Gray Girling that was
15  *    obtained from branch "rpi-3.6.y" of git://github.com/raspberrypi/
16  *    linux.git
17  *  - drivers/mailbox/bcm2835-ipc.c by Lubomir Rintel at
18  *    https://github.com/hackerspace/rpi-linux/blob/lr-raspberry-pi/drivers/
19  *    mailbox/bcm2835-ipc.c
20  *  - documentation available on the following web site:
21  *    https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface
22  */
23 
24 #include <linux/device.h>
25 #include <linux/dma-mapping.h>
26 #include <linux/err.h>
27 #include <linux/interrupt.h>
28 #include <linux/irq.h>
29 #include <linux/kernel.h>
30 #include <linux/mailbox_controller.h>
31 #include <linux/module.h>
32 #include <linux/of_address.h>
33 #include <linux/of_irq.h>
34 #include <linux/platform_device.h>
35 #include <linux/spinlock.h>
36 
37 /* Mailboxes */
38 #define ARM_0_MAIL0	0x00
39 #define ARM_0_MAIL1	0x20
40 
41 /*
42  * Mailbox registers. We basically only support mailbox 0 & 1. We
43  * deliver to the VC in mailbox 1, it delivers to us in mailbox 0. See
44  * BCM2835-ARM-Peripherals.pdf section 1.3 for an explanation about
45  * the placement of memory barriers.
46  */
47 #define MAIL0_RD	(ARM_0_MAIL0 + 0x00)
48 #define MAIL0_POL	(ARM_0_MAIL0 + 0x10)
49 #define MAIL0_STA	(ARM_0_MAIL0 + 0x18)
50 #define MAIL0_CNF	(ARM_0_MAIL0 + 0x1C)
51 #define MAIL1_WRT	(ARM_0_MAIL1 + 0x00)
52 #define MAIL1_STA	(ARM_0_MAIL1 + 0x18)
53 
54 /* Status register: FIFO state. */
55 #define ARM_MS_FULL		BIT(31)
56 #define ARM_MS_EMPTY		BIT(30)
57 
58 /* Configuration register: Enable interrupts. */
59 #define ARM_MC_IHAVEDATAIRQEN	BIT(0)
60 
61 struct bcm2835_mbox {
62 	void __iomem *regs;
63 	spinlock_t lock;
64 	struct mbox_controller controller;
65 };
66 
67 static struct bcm2835_mbox *bcm2835_link_mbox(struct mbox_chan *link)
68 {
69 	return container_of(link->mbox, struct bcm2835_mbox, controller);
70 }
71 
72 static irqreturn_t bcm2835_mbox_irq(int irq, void *dev_id)
73 {
74 	struct bcm2835_mbox *mbox = dev_id;
75 	struct device *dev = mbox->controller.dev;
76 	struct mbox_chan *link = &mbox->controller.chans[0];
77 
78 	while (!(readl(mbox->regs + MAIL0_STA) & ARM_MS_EMPTY)) {
79 		u32 msg = readl(mbox->regs + MAIL0_RD);
80 		dev_dbg(dev, "Reply 0x%08X\n", msg);
81 		mbox_chan_received_data(link, &msg);
82 	}
83 	return IRQ_HANDLED;
84 }
85 
86 static int bcm2835_send_data(struct mbox_chan *link, void *data)
87 {
88 	struct bcm2835_mbox *mbox = bcm2835_link_mbox(link);
89 	u32 msg = *(u32 *)data;
90 
91 	spin_lock(&mbox->lock);
92 	writel(msg, mbox->regs + MAIL1_WRT);
93 	dev_dbg(mbox->controller.dev, "Request 0x%08X\n", msg);
94 	spin_unlock(&mbox->lock);
95 	return 0;
96 }
97 
98 static int bcm2835_startup(struct mbox_chan *link)
99 {
100 	struct bcm2835_mbox *mbox = bcm2835_link_mbox(link);
101 
102 	/* Enable the interrupt on data reception */
103 	writel(ARM_MC_IHAVEDATAIRQEN, mbox->regs + MAIL0_CNF);
104 
105 	return 0;
106 }
107 
108 static void bcm2835_shutdown(struct mbox_chan *link)
109 {
110 	struct bcm2835_mbox *mbox = bcm2835_link_mbox(link);
111 
112 	writel(0, mbox->regs + MAIL0_CNF);
113 }
114 
115 static bool bcm2835_last_tx_done(struct mbox_chan *link)
116 {
117 	struct bcm2835_mbox *mbox = bcm2835_link_mbox(link);
118 	bool ret;
119 
120 	spin_lock(&mbox->lock);
121 	ret = !(readl(mbox->regs + MAIL1_STA) & ARM_MS_FULL);
122 	spin_unlock(&mbox->lock);
123 	return ret;
124 }
125 
126 static const struct mbox_chan_ops bcm2835_mbox_chan_ops = {
127 	.send_data	= bcm2835_send_data,
128 	.startup	= bcm2835_startup,
129 	.shutdown	= bcm2835_shutdown,
130 	.last_tx_done	= bcm2835_last_tx_done
131 };
132 
133 static struct mbox_chan *bcm2835_mbox_index_xlate(struct mbox_controller *mbox,
134 		    const struct of_phandle_args *sp)
135 {
136 	if (sp->args_count != 0)
137 		return NULL;
138 
139 	return &mbox->chans[0];
140 }
141 
142 static int bcm2835_mbox_probe(struct platform_device *pdev)
143 {
144 	struct device *dev = &pdev->dev;
145 	int ret = 0;
146 	struct resource *iomem;
147 	struct bcm2835_mbox *mbox;
148 
149 	mbox = devm_kzalloc(dev, sizeof(*mbox), GFP_KERNEL);
150 	if (mbox == NULL)
151 		return -ENOMEM;
152 	spin_lock_init(&mbox->lock);
153 
154 	ret = devm_request_irq(dev, irq_of_parse_and_map(dev->of_node, 0),
155 			       bcm2835_mbox_irq, 0, dev_name(dev), mbox);
156 	if (ret) {
157 		dev_err(dev, "Failed to register a mailbox IRQ handler: %d\n",
158 			ret);
159 		return -ENODEV;
160 	}
161 
162 	iomem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
163 	mbox->regs = devm_ioremap_resource(&pdev->dev, iomem);
164 	if (IS_ERR(mbox->regs)) {
165 		ret = PTR_ERR(mbox->regs);
166 		dev_err(&pdev->dev, "Failed to remap mailbox regs: %d\n", ret);
167 		return ret;
168 	}
169 
170 	mbox->controller.txdone_poll = true;
171 	mbox->controller.txpoll_period = 5;
172 	mbox->controller.ops = &bcm2835_mbox_chan_ops;
173 	mbox->controller.of_xlate = &bcm2835_mbox_index_xlate;
174 	mbox->controller.dev = dev;
175 	mbox->controller.num_chans = 1;
176 	mbox->controller.chans = devm_kzalloc(dev,
177 		sizeof(*mbox->controller.chans), GFP_KERNEL);
178 	if (!mbox->controller.chans)
179 		return -ENOMEM;
180 
181 	ret = mbox_controller_register(&mbox->controller);
182 	if (ret)
183 		return ret;
184 
185 	platform_set_drvdata(pdev, mbox);
186 	dev_info(dev, "mailbox enabled\n");
187 
188 	return ret;
189 }
190 
191 static int bcm2835_mbox_remove(struct platform_device *pdev)
192 {
193 	struct bcm2835_mbox *mbox = platform_get_drvdata(pdev);
194 	mbox_controller_unregister(&mbox->controller);
195 	return 0;
196 }
197 
198 static const struct of_device_id bcm2835_mbox_of_match[] = {
199 	{ .compatible = "brcm,bcm2835-mbox", },
200 	{},
201 };
202 MODULE_DEVICE_TABLE(of, bcm2835_mbox_of_match);
203 
204 static struct platform_driver bcm2835_mbox_driver = {
205 	.driver = {
206 		.name = "bcm2835-mbox",
207 		.of_match_table = bcm2835_mbox_of_match,
208 	},
209 	.probe		= bcm2835_mbox_probe,
210 	.remove		= bcm2835_mbox_remove,
211 };
212 module_platform_driver(bcm2835_mbox_driver);
213 
214 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
215 MODULE_DESCRIPTION("BCM2835 mailbox IPC driver");
216 MODULE_LICENSE("GPL v2");
217