1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  Copyright (C) 2010,2015 Broadcom
4  *  Copyright (C) 2013-2014 Lubomir Rintel
5  *  Copyright (C) 2013 Craig McGeachie
6  *
7  * Parts of the driver are based on:
8  *  - arch/arm/mach-bcm2708/vcio.c file written by Gray Girling that was
9  *    obtained from branch "rpi-3.6.y" of git://github.com/raspberrypi/
10  *    linux.git
11  *  - drivers/mailbox/bcm2835-ipc.c by Lubomir Rintel at
12  *    https://github.com/hackerspace/rpi-linux/blob/lr-raspberry-pi/drivers/
13  *    mailbox/bcm2835-ipc.c
14  *  - documentation available on the following web site:
15  *    https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface
16  */
17 
18 #include <linux/device.h>
19 #include <linux/dma-mapping.h>
20 #include <linux/err.h>
21 #include <linux/interrupt.h>
22 #include <linux/irq.h>
23 #include <linux/kernel.h>
24 #include <linux/mailbox_controller.h>
25 #include <linux/module.h>
26 #include <linux/of_address.h>
27 #include <linux/of_irq.h>
28 #include <linux/platform_device.h>
29 #include <linux/spinlock.h>
30 
31 /* Mailboxes */
32 #define ARM_0_MAIL0	0x00
33 #define ARM_0_MAIL1	0x20
34 
35 /*
36  * Mailbox registers. We basically only support mailbox 0 & 1. We
37  * deliver to the VC in mailbox 1, it delivers to us in mailbox 0. See
38  * BCM2835-ARM-Peripherals.pdf section 1.3 for an explanation about
39  * the placement of memory barriers.
40  */
41 #define MAIL0_RD	(ARM_0_MAIL0 + 0x00)
42 #define MAIL0_POL	(ARM_0_MAIL0 + 0x10)
43 #define MAIL0_STA	(ARM_0_MAIL0 + 0x18)
44 #define MAIL0_CNF	(ARM_0_MAIL0 + 0x1C)
45 #define MAIL1_WRT	(ARM_0_MAIL1 + 0x00)
46 #define MAIL1_STA	(ARM_0_MAIL1 + 0x18)
47 
48 /* Status register: FIFO state. */
49 #define ARM_MS_FULL		BIT(31)
50 #define ARM_MS_EMPTY		BIT(30)
51 
52 /* Configuration register: Enable interrupts. */
53 #define ARM_MC_IHAVEDATAIRQEN	BIT(0)
54 
55 struct bcm2835_mbox {
56 	void __iomem *regs;
57 	spinlock_t lock;
58 	struct mbox_controller controller;
59 };
60 
61 static struct bcm2835_mbox *bcm2835_link_mbox(struct mbox_chan *link)
62 {
63 	return container_of(link->mbox, struct bcm2835_mbox, controller);
64 }
65 
66 static irqreturn_t bcm2835_mbox_irq(int irq, void *dev_id)
67 {
68 	struct bcm2835_mbox *mbox = dev_id;
69 	struct device *dev = mbox->controller.dev;
70 	struct mbox_chan *link = &mbox->controller.chans[0];
71 
72 	while (!(readl(mbox->regs + MAIL0_STA) & ARM_MS_EMPTY)) {
73 		u32 msg = readl(mbox->regs + MAIL0_RD);
74 		dev_dbg(dev, "Reply 0x%08X\n", msg);
75 		mbox_chan_received_data(link, &msg);
76 	}
77 	return IRQ_HANDLED;
78 }
79 
80 static int bcm2835_send_data(struct mbox_chan *link, void *data)
81 {
82 	struct bcm2835_mbox *mbox = bcm2835_link_mbox(link);
83 	u32 msg = *(u32 *)data;
84 
85 	spin_lock(&mbox->lock);
86 	writel(msg, mbox->regs + MAIL1_WRT);
87 	dev_dbg(mbox->controller.dev, "Request 0x%08X\n", msg);
88 	spin_unlock(&mbox->lock);
89 	return 0;
90 }
91 
92 static int bcm2835_startup(struct mbox_chan *link)
93 {
94 	struct bcm2835_mbox *mbox = bcm2835_link_mbox(link);
95 
96 	/* Enable the interrupt on data reception */
97 	writel(ARM_MC_IHAVEDATAIRQEN, mbox->regs + MAIL0_CNF);
98 
99 	return 0;
100 }
101 
102 static void bcm2835_shutdown(struct mbox_chan *link)
103 {
104 	struct bcm2835_mbox *mbox = bcm2835_link_mbox(link);
105 
106 	writel(0, mbox->regs + MAIL0_CNF);
107 }
108 
109 static bool bcm2835_last_tx_done(struct mbox_chan *link)
110 {
111 	struct bcm2835_mbox *mbox = bcm2835_link_mbox(link);
112 	bool ret;
113 
114 	spin_lock(&mbox->lock);
115 	ret = !(readl(mbox->regs + MAIL1_STA) & ARM_MS_FULL);
116 	spin_unlock(&mbox->lock);
117 	return ret;
118 }
119 
120 static const struct mbox_chan_ops bcm2835_mbox_chan_ops = {
121 	.send_data	= bcm2835_send_data,
122 	.startup	= bcm2835_startup,
123 	.shutdown	= bcm2835_shutdown,
124 	.last_tx_done	= bcm2835_last_tx_done
125 };
126 
127 static struct mbox_chan *bcm2835_mbox_index_xlate(struct mbox_controller *mbox,
128 		    const struct of_phandle_args *sp)
129 {
130 	if (sp->args_count != 0)
131 		return ERR_PTR(-EINVAL);
132 
133 	return &mbox->chans[0];
134 }
135 
136 static int bcm2835_mbox_probe(struct platform_device *pdev)
137 {
138 	struct device *dev = &pdev->dev;
139 	int ret = 0;
140 	struct resource *iomem;
141 	struct bcm2835_mbox *mbox;
142 
143 	mbox = devm_kzalloc(dev, sizeof(*mbox), GFP_KERNEL);
144 	if (mbox == NULL)
145 		return -ENOMEM;
146 	spin_lock_init(&mbox->lock);
147 
148 	ret = devm_request_irq(dev, irq_of_parse_and_map(dev->of_node, 0),
149 			       bcm2835_mbox_irq, 0, dev_name(dev), mbox);
150 	if (ret) {
151 		dev_err(dev, "Failed to register a mailbox IRQ handler: %d\n",
152 			ret);
153 		return -ENODEV;
154 	}
155 
156 	iomem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
157 	mbox->regs = devm_ioremap_resource(&pdev->dev, iomem);
158 	if (IS_ERR(mbox->regs)) {
159 		ret = PTR_ERR(mbox->regs);
160 		dev_err(&pdev->dev, "Failed to remap mailbox regs: %d\n", ret);
161 		return ret;
162 	}
163 
164 	mbox->controller.txdone_poll = true;
165 	mbox->controller.txpoll_period = 5;
166 	mbox->controller.ops = &bcm2835_mbox_chan_ops;
167 	mbox->controller.of_xlate = &bcm2835_mbox_index_xlate;
168 	mbox->controller.dev = dev;
169 	mbox->controller.num_chans = 1;
170 	mbox->controller.chans = devm_kzalloc(dev,
171 		sizeof(*mbox->controller.chans), GFP_KERNEL);
172 	if (!mbox->controller.chans)
173 		return -ENOMEM;
174 
175 	ret = devm_mbox_controller_register(dev, &mbox->controller);
176 	if (ret)
177 		return ret;
178 
179 	platform_set_drvdata(pdev, mbox);
180 	dev_info(dev, "mailbox enabled\n");
181 
182 	return ret;
183 }
184 
185 static const struct of_device_id bcm2835_mbox_of_match[] = {
186 	{ .compatible = "brcm,bcm2835-mbox", },
187 	{},
188 };
189 MODULE_DEVICE_TABLE(of, bcm2835_mbox_of_match);
190 
191 static struct platform_driver bcm2835_mbox_driver = {
192 	.driver = {
193 		.name = "bcm2835-mbox",
194 		.of_match_table = bcm2835_mbox_of_match,
195 	},
196 	.probe		= bcm2835_mbox_probe,
197 };
198 module_platform_driver(bcm2835_mbox_driver);
199 
200 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
201 MODULE_DESCRIPTION("BCM2835 mailbox IPC driver");
202 MODULE_LICENSE("GPL v2");
203