drivers/mailbox/sun6i-msgbox.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 //
   3 // Copyright (c) 2017-2019 Samuel Holland <samuel@sholland.org>
   4
   5 #include <linux/bitops.h>
   6 #include <linux/clk.h>
   7 #include <linux/device.h>
   8 #include <linux/err.h>
   9 #include <linux/interrupt.h>
  10 #include <linux/io.h>
  11 #include <linux/kernel.h>
  12 #include <linux/mailbox_controller.h>
  13 #include <linux/module.h>
  14 #include <linux/of.h>
  15 #include <linux/of_irq.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/reset.h>
  18 #include <linux/spinlock.h>
  19
  20 #define NUM_CHANS               8
  21
  22 #define CTRL_REG(n)             (0x0000 + 0x4 * ((n) / 4))
  23 #define CTRL_RX(n)              BIT(0 + 8 * ((n) % 4))
  24 #define CTRL_TX(n)              BIT(4 + 8 * ((n) % 4))
  25
  26 #define REMOTE_IRQ_EN_REG       0x0040
  27 #define REMOTE_IRQ_STAT_REG     0x0050
  28 #define LOCAL_IRQ_EN_REG        0x0060
  29 #define LOCAL_IRQ_STAT_REG      0x0070
  30
  31 #define RX_IRQ(n)               BIT(0 + 2 * (n))
  32 #define RX_IRQ_MASK             0x5555
  33 #define TX_IRQ(n)               BIT(1 + 2 * (n))
  34 #define TX_IRQ_MASK             0xaaaa
  35
  36 #define FIFO_STAT_REG(n)        (0x0100 + 0x4 * (n))
  37 #define FIFO_STAT_MASK          GENMASK(0, 0)
  38
  39 #define MSG_STAT_REG(n)         (0x0140 + 0x4 * (n))
  40 #define MSG_STAT_MASK           GENMASK(2, 0)
  41
  42 #define MSG_DATA_REG(n)         (0x0180 + 0x4 * (n))
  43
  44 #define mbox_dbg(mbox, ...)     dev_dbg((mbox)->controller.dev, __VA_ARGS__)
  45
  46 struct sun6i_msgbox {
  47         struct mbox_controller controller;
  48         struct clk *clk;
  49         spinlock_t lock;
  50         void __iomem *regs;
  51 };
  52
  53 static bool sun6i_msgbox_last_tx_done(struct mbox_chan *chan);
  54 static bool sun6i_msgbox_peek_data(struct mbox_chan *chan);
  55
  56 static inline int channel_number(struct mbox_chan *chan)
  57 {
  58         return chan - chan->mbox->chans;
  59 }
  60
  61 static inline struct sun6i_msgbox *to_sun6i_msgbox(struct mbox_chan *chan)
  62 {
  63         return chan->con_priv;
  64 }
  65
  66 static irqreturn_t sun6i_msgbox_irq(int irq, void *dev_id)
  67 {
  68         struct sun6i_msgbox *mbox = dev_id;
  69         uint32_t status;
  70         int n;
  71
  72         /* Only examine channels that are currently enabled. */
  73         status = readl(mbox->regs + LOCAL_IRQ_EN_REG) &
  74                  readl(mbox->regs + LOCAL_IRQ_STAT_REG);
  75
  76         if (!(status & RX_IRQ_MASK))
  77                 return IRQ_NONE;
  78
  79         for (n = 0; n < NUM_CHANS; ++n) {
  80                 struct mbox_chan *chan = &mbox->controller.chans[n];
  81
  82                 if (!(status & RX_IRQ(n)))
  83                         continue;
  84
  85                 while (sun6i_msgbox_peek_data(chan)) {
  86                         uint32_t msg = readl(mbox->regs + MSG_DATA_REG(n));
  87
  88                         mbox_dbg(mbox, "Channel %d received 0x%08x\n", n, msg);
  89                         mbox_chan_received_data(chan, &msg);
  90                 }
  91
  92                 /* The IRQ can be cleared only once the FIFO is empty. */
  93                 writel(RX_IRQ(n), mbox->regs + LOCAL_IRQ_STAT_REG);
  94         }
  95
  96         return IRQ_HANDLED;
  97 }
  98
  99 static int sun6i_msgbox_send_data(struct mbox_chan *chan, void *data)
 100 {
 101         struct sun6i_msgbox *mbox = to_sun6i_msgbox(chan);
 102         int n = channel_number(chan);
 103         uint32_t msg = *(uint32_t *)data;
 104
 105         /* Using a channel backwards gets the hardware into a bad state. */
 106         if (WARN_ON_ONCE(!(readl(mbox->regs + CTRL_REG(n)) & CTRL_TX(n))))
 107                 return 0;
 108
 109         writel(msg, mbox->regs + MSG_DATA_REG(n));
 110         mbox_dbg(mbox, "Channel %d sent 0x%08x\n", n, msg);
 111
 112         return 0;
 113 }
 114
 115 static int sun6i_msgbox_startup(struct mbox_chan *chan)
 116 {
 117         struct sun6i_msgbox *mbox = to_sun6i_msgbox(chan);
 118         int n = channel_number(chan);
 119
 120         /* The coprocessor is responsible for setting channel directions. */
 121         if (readl(mbox->regs + CTRL_REG(n)) & CTRL_RX(n)) {
 122                 /* Flush the receive FIFO. */
 123                 while (sun6i_msgbox_peek_data(chan))
 124                         readl(mbox->regs + MSG_DATA_REG(n));
 125                 writel(RX_IRQ(n), mbox->regs + LOCAL_IRQ_STAT_REG);
 126
 127                 /* Enable the receive IRQ. */
 128                 spin_lock(&mbox->lock);
 129                 writel(readl(mbox->regs + LOCAL_IRQ_EN_REG) | RX_IRQ(n),
 130                        mbox->regs + LOCAL_IRQ_EN_REG);
 131                 spin_unlock(&mbox->lock);
 132         }
 133
 134         mbox_dbg(mbox, "Channel %d startup complete\n", n);
 135
 136         return 0;
 137 }
 138
 139 static void sun6i_msgbox_shutdown(struct mbox_chan *chan)
 140 {
 141         struct sun6i_msgbox *mbox = to_sun6i_msgbox(chan);
 142         int n = channel_number(chan);
 143
 144         if (readl(mbox->regs + CTRL_REG(n)) & CTRL_RX(n)) {
 145                 /* Disable the receive IRQ. */
 146                 spin_lock(&mbox->lock);
 147                 writel(readl(mbox->regs + LOCAL_IRQ_EN_REG) & ~RX_IRQ(n),
 148                        mbox->regs + LOCAL_IRQ_EN_REG);
 149                 spin_unlock(&mbox->lock);
 150
 151                 /* Attempt to flush the FIFO until the IRQ is cleared. */
 152                 do {
 153                         while (sun6i_msgbox_peek_data(chan))
 154                                 readl(mbox->regs + MSG_DATA_REG(n));
 155                         writel(RX_IRQ(n), mbox->regs + LOCAL_IRQ_STAT_REG);
 156                 } while (readl(mbox->regs + LOCAL_IRQ_STAT_REG) & RX_IRQ(n));
 157         }
 158
 159         mbox_dbg(mbox, "Channel %d shutdown complete\n", n);
 160 }
 161
 162 static bool sun6i_msgbox_last_tx_done(struct mbox_chan *chan)
 163 {
 164         struct sun6i_msgbox *mbox = to_sun6i_msgbox(chan);
 165         int n = channel_number(chan);
 166
 167         /*
 168          * The hardware allows snooping on the remote user's IRQ statuses.
 169          * We consider a message to be acknowledged only once the receive IRQ
 170          * for that channel is cleared. Since the receive IRQ for a channel
 171          * cannot be cleared until the FIFO for that channel is empty, this
 172          * ensures that the message has actually been read. It also gives the
 173          * recipient an opportunity to perform minimal processing before
 174          * acknowledging the message.
 175          */
 176         return !(readl(mbox->regs + REMOTE_IRQ_STAT_REG) & RX_IRQ(n));
 177 }
 178
 179 static bool sun6i_msgbox_peek_data(struct mbox_chan *chan)
 180 {
 181         struct sun6i_msgbox *mbox = to_sun6i_msgbox(chan);
 182         int n = channel_number(chan);
 183
 184         return readl(mbox->regs + MSG_STAT_REG(n)) & MSG_STAT_MASK;
 185 }
 186
 187 static const struct mbox_chan_ops sun6i_msgbox_chan_ops = {
 188         .send_data    = sun6i_msgbox_send_data,
 189         .startup      = sun6i_msgbox_startup,
 190         .shutdown     = sun6i_msgbox_shutdown,
 191         .last_tx_done = sun6i_msgbox_last_tx_done,
 192         .peek_data    = sun6i_msgbox_peek_data,
 193 };
 194
 195 static int sun6i_msgbox_probe(struct platform_device *pdev)
 196 {
 197         struct device *dev = &pdev->dev;
 198         struct mbox_chan *chans;
 199         struct reset_control *reset;
 200         struct resource *res;
 201         struct sun6i_msgbox *mbox;
 202         int i, ret;
 203
 204         mbox = devm_kzalloc(dev, sizeof(*mbox), GFP_KERNEL);
 205         if (!mbox)
 206                 return -ENOMEM;
 207
 208         chans = devm_kcalloc(dev, NUM_CHANS, sizeof(*chans), GFP_KERNEL);
 209         if (!chans)
 210                 return -ENOMEM;
 211
 212         for (i = 0; i < NUM_CHANS; ++i)
 213                 chans[i].con_priv = mbox;
 214
 215         mbox->clk = devm_clk_get(dev, NULL);
 216         if (IS_ERR(mbox->clk)) {
 217                 ret = PTR_ERR(mbox->clk);
 218                 dev_err(dev, "Failed to get clock: %d\n", ret);
 219                 return ret;
 220         }
 221
 222         ret = clk_prepare_enable(mbox->clk);
 223         if (ret) {
 224                 dev_err(dev, "Failed to enable clock: %d\n", ret);
 225                 return ret;
 226         }
 227
 228         reset = devm_reset_control_get_exclusive(dev, NULL);
 229         if (IS_ERR(reset)) {
 230                 ret = PTR_ERR(reset);
 231                 dev_err(dev, "Failed to get reset control: %d\n", ret);
 232                 goto err_disable_unprepare;
 233         }
 234
 235         /*
 236          * NOTE: We rely on platform firmware to preconfigure the channel
 237          * directions, and we share this hardware block with other firmware
 238          * that runs concurrently with Linux (e.g. a trusted monitor).
 239          *
 240          * Therefore, we do *not* assert the reset line if probing fails or
 241          * when removing the device.
 242          */
 243         ret = reset_control_deassert(reset);
 244         if (ret) {
 245                 dev_err(dev, "Failed to deassert reset: %d\n", ret);
 246                 goto err_disable_unprepare;
 247         }
 248
 249         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 250         if (!res) {
 251                 ret = -ENODEV;
 252                 goto err_disable_unprepare;
 253         }
 254
 255         mbox->regs = devm_ioremap_resource(&pdev->dev, res);
 256         if (IS_ERR(mbox->regs)) {
 257                 ret = PTR_ERR(mbox->regs);
 258                 dev_err(dev, "Failed to map MMIO resource: %d\n", ret);
 259                 goto err_disable_unprepare;
 260         }
 261
 262         /* Disable all IRQs for this end of the msgbox. */
 263         writel(0, mbox->regs + LOCAL_IRQ_EN_REG);
 264
 265         ret = devm_request_irq(dev, irq_of_parse_and_map(dev->of_node, 0),
 266                                sun6i_msgbox_irq, 0, dev_name(dev), mbox);
 267         if (ret) {
 268                 dev_err(dev, "Failed to register IRQ handler: %d\n", ret);
 269                 goto err_disable_unprepare;
 270         }
 271
 272         mbox->controller.dev           = dev;
 273         mbox->controller.ops           = &sun6i_msgbox_chan_ops;
 274         mbox->controller.chans         = chans;
 275         mbox->controller.num_chans     = NUM_CHANS;
 276         mbox->controller.txdone_irq    = false;
 277         mbox->controller.txdone_poll   = true;
 278         mbox->controller.txpoll_period = 5;
 279
 280         spin_lock_init(&mbox->lock);
 281         platform_set_drvdata(pdev, mbox);
 282
 283         ret = mbox_controller_register(&mbox->controller);
 284         if (ret) {
 285                 dev_err(dev, "Failed to register controller: %d\n", ret);
 286                 goto err_disable_unprepare;
 287         }
 288
 289         return 0;
 290
 291 err_disable_unprepare:
 292         clk_disable_unprepare(mbox->clk);
 293
 294         return ret;
 295 }
 296
 297 static int sun6i_msgbox_remove(struct platform_device *pdev)
 298 {
 299         struct sun6i_msgbox *mbox = platform_get_drvdata(pdev);
 300
 301         mbox_controller_unregister(&mbox->controller);
 302         /* See the comment in sun6i_msgbox_probe about the reset line. */
 303         clk_disable_unprepare(mbox->clk);
 304
 305         return 0;
 306 }
 307
 308 static const struct of_device_id sun6i_msgbox_of_match[] = {
 309         { .compatible = "allwinner,sun6i-a31-msgbox", },
 310         {},
 311 };
 312 MODULE_DEVICE_TABLE(of, sun6i_msgbox_of_match);
 313
 314 static struct platform_driver sun6i_msgbox_driver = {
 315         .driver = {
 316                 .name = "sun6i-msgbox",
 317                 .of_match_table = sun6i_msgbox_of_match,
 318         },
 319         .probe  = sun6i_msgbox_probe,
 320         .remove = sun6i_msgbox_remove,
 321 };
 322 module_platform_driver(sun6i_msgbox_driver);
 323
 324 MODULE_AUTHOR("Samuel Holland <samuel@sholland.org>");
 325 MODULE_DESCRIPTION("Allwinner sun6i/sun8i/sun9i/sun50i Message Box");
 326 MODULE_LICENSE("GPL v2");