drivers/mailbox/bcm2835-mailbox.c

   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 bcm2835_mbox *mbox;
 141
 142         mbox = devm_kzalloc(dev, sizeof(*mbox), GFP_KERNEL);
 143         if (mbox == NULL)
 144                 return -ENOMEM;
 145         spin_lock_init(&mbox->lock);
 146
 147         ret = devm_request_irq(dev, irq_of_parse_and_map(dev->of_node, 0),
 148                                bcm2835_mbox_irq, IRQF_NO_SUSPEND, dev_name(dev),
 149                                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         mbox->regs = devm_platform_ioremap_resource(pdev, 0);
 157         if (IS_ERR(mbox->regs)) {
 158                 ret = PTR_ERR(mbox->regs);
 159                 return ret;
 160         }
 161
 162         mbox->controller.txdone_poll = true;
 163         mbox->controller.txpoll_period = 5;
 164         mbox->controller.ops = &bcm2835_mbox_chan_ops;
 165         mbox->controller.of_xlate = &bcm2835_mbox_index_xlate;
 166         mbox->controller.dev = dev;
 167         mbox->controller.num_chans = 1;
 168         mbox->controller.chans = devm_kzalloc(dev,
 169                 sizeof(*mbox->controller.chans), GFP_KERNEL);
 170         if (!mbox->controller.chans)
 171                 return -ENOMEM;
 172
 173         ret = devm_mbox_controller_register(dev, &mbox->controller);
 174         if (ret)
 175                 return ret;
 176
 177         platform_set_drvdata(pdev, mbox);
 178         dev_info(dev, "mailbox enabled\n");
 179
 180         return ret;
 181 }
 182
 183 static const struct of_device_id bcm2835_mbox_of_match[] = {
 184         { .compatible = "brcm,bcm2835-mbox", },
 185         {},
 186 };
 187 MODULE_DEVICE_TABLE(of, bcm2835_mbox_of_match);
 188
 189 static struct platform_driver bcm2835_mbox_driver = {
 190         .driver = {
 191                 .name = "bcm2835-mbox",
 192                 .of_match_table = bcm2835_mbox_of_match,
 193         },
 194         .probe          = bcm2835_mbox_probe,
 195 };
 196 module_platform_driver(bcm2835_mbox_driver);
 197
 198 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
 199 MODULE_DESCRIPTION("BCM2835 mailbox IPC driver");
 200 MODULE_LICENSE("GPL v2");