drivers/mailbox/bcm2835-mailbox.c

   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 ERR_PTR(-EINVAL);
 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");