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
bcm2835_link_mbox(struct mbox_chan * link)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
bcm2835_mbox_irq(int irq,void * dev_id)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
bcm2835_send_data(struct mbox_chan * link,void * data)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
bcm2835_startup(struct mbox_chan * link)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
bcm2835_shutdown(struct mbox_chan * link)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
bcm2835_last_tx_done(struct mbox_chan * link)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
bcm2835_mbox_index_xlate(struct mbox_controller * mbox,const struct of_phandle_args * sp)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
bcm2835_mbox_probe(struct platform_device * pdev)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 return ret;
161 }
162
163 mbox->controller.txdone_poll = true;
164 mbox->controller.txpoll_period = 5;
165 mbox->controller.ops = &bcm2835_mbox_chan_ops;
166 mbox->controller.of_xlate = &bcm2835_mbox_index_xlate;
167 mbox->controller.dev = dev;
168 mbox->controller.num_chans = 1;
169 mbox->controller.chans = devm_kzalloc(dev,
170 sizeof(*mbox->controller.chans), GFP_KERNEL);
171 if (!mbox->controller.chans)
172 return -ENOMEM;
173
174 ret = devm_mbox_controller_register(dev, &mbox->controller);
175 if (ret)
176 return ret;
177
178 platform_set_drvdata(pdev, mbox);
179 dev_info(dev, "mailbox enabled\n");
180
181 return ret;
182 }
183
184 static const struct of_device_id bcm2835_mbox_of_match[] = {
185 { .compatible = "brcm,bcm2835-mbox", },
186 {},
187 };
188 MODULE_DEVICE_TABLE(of, bcm2835_mbox_of_match);
189
190 static struct platform_driver bcm2835_mbox_driver = {
191 .driver = {
192 .name = "bcm2835-mbox",
193 .of_match_table = bcm2835_mbox_of_match,
194 },
195 .probe = bcm2835_mbox_probe,
196 };
197 module_platform_driver(bcm2835_mbox_driver);
198
199 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
200 MODULE_DESCRIPTION("BCM2835 mailbox IPC driver");
201 MODULE_LICENSE("GPL v2");
202
