drivers/mailbox/imx-mailbox.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2018 Pengutronix, Oleksij Rempel <o.rempel@pengutronix.de>
   4  */
   5
   6 #include <linux/clk.h>
   7 #include <linux/firmware/imx/ipc.h>
   8 #include <linux/interrupt.h>
   9 #include <linux/io.h>
  10 #include <linux/iopoll.h>
  11 #include <linux/kernel.h>
  12 #include <linux/mailbox_controller.h>
  13 #include <linux/module.h>
  14 #include <linux/of_device.h>
  15 #include <linux/pm_runtime.h>
  16 #include <linux/slab.h>
  17
  18 #define IMX_MU_xSR_GIPn(x)      BIT(28 + (3 - (x)))
  19 #define IMX_MU_xSR_RFn(x)       BIT(24 + (3 - (x)))
  20 #define IMX_MU_xSR_TEn(x)       BIT(20 + (3 - (x)))
  21 #define IMX_MU_xSR_BRDIP        BIT(9)
  22
  23 /* General Purpose Interrupt Enable */
  24 #define IMX_MU_xCR_GIEn(x)      BIT(28 + (3 - (x)))
  25 /* Receive Interrupt Enable */
  26 #define IMX_MU_xCR_RIEn(x)      BIT(24 + (3 - (x)))
  27 /* Transmit Interrupt Enable */
  28 #define IMX_MU_xCR_TIEn(x)      BIT(20 + (3 - (x)))
  29 /* General Purpose Interrupt Request */
  30 #define IMX_MU_xCR_GIRn(x)      BIT(16 + (3 - (x)))
  31
  32 #define IMX_MU_CHANS            16
  33 /* TX0/RX0/RXDB[0-3] */
  34 #define IMX_MU_SCU_CHANS        6
  35 #define IMX_MU_CHAN_NAME_SIZE   20
  36
  37 enum imx_mu_chan_type {
  38         IMX_MU_TYPE_TX,         /* Tx */
  39         IMX_MU_TYPE_RX,         /* Rx */
  40         IMX_MU_TYPE_TXDB,       /* Tx doorbell */
  41         IMX_MU_TYPE_RXDB,       /* Rx doorbell */
  42 };
  43
  44 struct imx_sc_rpc_msg_max {
  45         struct imx_sc_rpc_msg hdr;
  46         u32 data[7];
  47 };
  48
  49 struct imx_mu_con_priv {
  50         unsigned int            idx;
  51         char                    irq_desc[IMX_MU_CHAN_NAME_SIZE];
  52         enum imx_mu_chan_type   type;
  53         struct mbox_chan        *chan;
  54         struct tasklet_struct   txdb_tasklet;
  55 };
  56
  57 struct imx_mu_priv {
  58         struct device           *dev;
  59         void __iomem            *base;
  60         spinlock_t              xcr_lock; /* control register lock */
  61
  62         struct mbox_controller  mbox;
  63         struct mbox_chan        mbox_chans[IMX_MU_CHANS];
  64
  65         struct imx_mu_con_priv  con_priv[IMX_MU_CHANS];
  66         const struct imx_mu_dcfg        *dcfg;
  67         struct clk              *clk;
  68         int                     irq;
  69
  70         u32 xcr;
  71
  72         bool                    side_b;
  73 };
  74
  75 struct imx_mu_dcfg {
  76         int (*tx)(struct imx_mu_priv *priv, struct imx_mu_con_priv *cp, void *data);
  77         int (*rx)(struct imx_mu_priv *priv, struct imx_mu_con_priv *cp);
  78         void (*init)(struct imx_mu_priv *priv);
  79         u32     xTR[4];         /* Transmit Registers */
  80         u32     xRR[4];         /* Receive Registers */
  81         u32     xSR;            /* Status Register */
  82         u32     xCR;            /* Control Register */
  83 };
  84
  85 static struct imx_mu_priv *to_imx_mu_priv(struct mbox_controller *mbox)
  86 {
  87         return container_of(mbox, struct imx_mu_priv, mbox);
  88 }
  89
  90 static void imx_mu_write(struct imx_mu_priv *priv, u32 val, u32 offs)
  91 {
  92         iowrite32(val, priv->base + offs);
  93 }
  94
  95 static u32 imx_mu_read(struct imx_mu_priv *priv, u32 offs)
  96 {
  97         return ioread32(priv->base + offs);
  98 }
  99
 100 static u32 imx_mu_xcr_rmw(struct imx_mu_priv *priv, u32 set, u32 clr)
 101 {
 102         unsigned long flags;
 103         u32 val;
 104
 105         spin_lock_irqsave(&priv->xcr_lock, flags);
 106         val = imx_mu_read(priv, priv->dcfg->xCR);
 107         val &= ~clr;
 108         val |= set;
 109         imx_mu_write(priv, val, priv->dcfg->xCR);
 110         spin_unlock_irqrestore(&priv->xcr_lock, flags);
 111
 112         return val;
 113 }
 114
 115 static int imx_mu_generic_tx(struct imx_mu_priv *priv,
 116                              struct imx_mu_con_priv *cp,
 117                              void *data)
 118 {
 119         u32 *arg = data;
 120
 121         switch (cp->type) {
 122         case IMX_MU_TYPE_TX:
 123                 imx_mu_write(priv, *arg, priv->dcfg->xTR[cp->idx]);
 124                 imx_mu_xcr_rmw(priv, IMX_MU_xCR_TIEn(cp->idx), 0);
 125                 break;
 126         case IMX_MU_TYPE_TXDB:
 127                 imx_mu_xcr_rmw(priv, IMX_MU_xCR_GIRn(cp->idx), 0);
 128                 tasklet_schedule(&cp->txdb_tasklet);
 129                 break;
 130         default:
 131                 dev_warn_ratelimited(priv->dev, "Send data on wrong channel type: %d\n", cp->type);
 132                 return -EINVAL;
 133         }
 134
 135         return 0;
 136 }
 137
 138 static int imx_mu_generic_rx(struct imx_mu_priv *priv,
 139                              struct imx_mu_con_priv *cp)
 140 {
 141         u32 dat;
 142
 143         dat = imx_mu_read(priv, priv->dcfg->xRR[cp->idx]);
 144         mbox_chan_received_data(cp->chan, (void *)&dat);
 145
 146         return 0;
 147 }
 148
 149 static int imx_mu_scu_tx(struct imx_mu_priv *priv,
 150                          struct imx_mu_con_priv *cp,
 151                          void *data)
 152 {
 153         struct imx_sc_rpc_msg_max *msg = data;
 154         u32 *arg = data;
 155         int i, ret;
 156         u32 xsr;
 157
 158         switch (cp->type) {
 159         case IMX_MU_TYPE_TX:
 160                 /*
 161                  * msg->hdr.size specifies the number of u32 words while
 162                  * sizeof yields bytes.
 163                  */
 164
 165                 if (msg->hdr.size > sizeof(*msg) / 4) {
 166                         /*
 167                          * The real message size can be different to
 168                          * struct imx_sc_rpc_msg_max size
 169                          */
 170                         dev_err(priv->dev, "Maximal message size (%zu bytes) exceeded on TX; got: %i bytes\n", sizeof(*msg), msg->hdr.size << 2);
 171                         return -EINVAL;
 172                 }
 173
 174                 for (i = 0; i < 4 && i < msg->hdr.size; i++)
 175                         imx_mu_write(priv, *arg++, priv->dcfg->xTR[i % 4]);
 176                 for (; i < msg->hdr.size; i++) {
 177                         ret = readl_poll_timeout(priv->base + priv->dcfg->xSR,
 178                                                  xsr,
 179                                                  xsr & IMX_MU_xSR_TEn(i % 4),
 180                                                  0, 100);
 181                         if (ret) {
 182                                 dev_err(priv->dev, "Send data index: %d timeout\n", i);
 183                                 return ret;
 184                         }
 185                         imx_mu_write(priv, *arg++, priv->dcfg->xTR[i % 4]);
 186                 }
 187
 188                 imx_mu_xcr_rmw(priv, IMX_MU_xCR_TIEn(cp->idx), 0);
 189                 break;
 190         default:
 191                 dev_warn_ratelimited(priv->dev, "Send data on wrong channel type: %d\n", cp->type);
 192                 return -EINVAL;
 193         }
 194
 195         return 0;
 196 }
 197
 198 static int imx_mu_scu_rx(struct imx_mu_priv *priv,
 199                          struct imx_mu_con_priv *cp)
 200 {
 201         struct imx_sc_rpc_msg_max msg;
 202         u32 *data = (u32 *)&msg;
 203         int i, ret;
 204         u32 xsr;
 205
 206         imx_mu_xcr_rmw(priv, 0, IMX_MU_xCR_RIEn(0));
 207         *data++ = imx_mu_read(priv, priv->dcfg->xRR[0]);
 208
 209         if (msg.hdr.size > sizeof(msg) / 4) {
 210                 dev_err(priv->dev, "Maximal message size (%zu bytes) exceeded on RX; got: %i bytes\n", sizeof(msg), msg.hdr.size << 2);
 211                 return -EINVAL;
 212         }
 213
 214         for (i = 1; i < msg.hdr.size; i++) {
 215                 ret = readl_poll_timeout(priv->base + priv->dcfg->xSR, xsr,
 216                                          xsr & IMX_MU_xSR_RFn(i % 4), 0, 100);
 217                 if (ret) {
 218                         dev_err(priv->dev, "timeout read idx %d\n", i);
 219                         return ret;
 220                 }
 221                 *data++ = imx_mu_read(priv, priv->dcfg->xRR[i % 4]);
 222         }
 223
 224         imx_mu_xcr_rmw(priv, IMX_MU_xCR_RIEn(0), 0);
 225         mbox_chan_received_data(cp->chan, (void *)&msg);
 226
 227         return 0;
 228 }
 229
 230 static void imx_mu_txdb_tasklet(unsigned long data)
 231 {
 232         struct imx_mu_con_priv *cp = (struct imx_mu_con_priv *)data;
 233
 234         mbox_chan_txdone(cp->chan, 0);
 235 }
 236
 237 static irqreturn_t imx_mu_isr(int irq, void *p)
 238 {
 239         struct mbox_chan *chan = p;
 240         struct imx_mu_priv *priv = to_imx_mu_priv(chan->mbox);
 241         struct imx_mu_con_priv *cp = chan->con_priv;
 242         u32 val, ctrl;
 243
 244         ctrl = imx_mu_read(priv, priv->dcfg->xCR);
 245         val = imx_mu_read(priv, priv->dcfg->xSR);
 246
 247         switch (cp->type) {
 248         case IMX_MU_TYPE_TX:
 249                 val &= IMX_MU_xSR_TEn(cp->idx) &
 250                         (ctrl & IMX_MU_xCR_TIEn(cp->idx));
 251                 break;
 252         case IMX_MU_TYPE_RX:
 253                 val &= IMX_MU_xSR_RFn(cp->idx) &
 254                         (ctrl & IMX_MU_xCR_RIEn(cp->idx));
 255                 break;
 256         case IMX_MU_TYPE_RXDB:
 257                 val &= IMX_MU_xSR_GIPn(cp->idx) &
 258                         (ctrl & IMX_MU_xCR_GIEn(cp->idx));
 259                 break;
 260         default:
 261                 break;
 262         }
 263
 264         if (!val)
 265                 return IRQ_NONE;
 266
 267         if (val == IMX_MU_xSR_TEn(cp->idx)) {
 268                 imx_mu_xcr_rmw(priv, 0, IMX_MU_xCR_TIEn(cp->idx));
 269                 mbox_chan_txdone(chan, 0);
 270         } else if (val == IMX_MU_xSR_RFn(cp->idx)) {
 271                 priv->dcfg->rx(priv, cp);
 272         } else if (val == IMX_MU_xSR_GIPn(cp->idx)) {
 273                 imx_mu_write(priv, IMX_MU_xSR_GIPn(cp->idx), priv->dcfg->xSR);
 274                 mbox_chan_received_data(chan, NULL);
 275         } else {
 276                 dev_warn_ratelimited(priv->dev, "Not handled interrupt\n");
 277                 return IRQ_NONE;
 278         }
 279
 280         return IRQ_HANDLED;
 281 }
 282
 283 static int imx_mu_send_data(struct mbox_chan *chan, void *data)
 284 {
 285         struct imx_mu_priv *priv = to_imx_mu_priv(chan->mbox);
 286         struct imx_mu_con_priv *cp = chan->con_priv;
 287
 288         return priv->dcfg->tx(priv, cp, data);
 289 }
 290
 291 static int imx_mu_startup(struct mbox_chan *chan)
 292 {
 293         struct imx_mu_priv *priv = to_imx_mu_priv(chan->mbox);
 294         struct imx_mu_con_priv *cp = chan->con_priv;
 295         int ret;
 296
 297         pm_runtime_get_sync(priv->dev);
 298         if (cp->type == IMX_MU_TYPE_TXDB) {
 299                 /* Tx doorbell don't have ACK support */
 300                 tasklet_init(&cp->txdb_tasklet, imx_mu_txdb_tasklet,
 301                              (unsigned long)cp);
 302                 return 0;
 303         }
 304
 305         ret = request_irq(priv->irq, imx_mu_isr, IRQF_SHARED |
 306                           IRQF_NO_SUSPEND, cp->irq_desc, chan);
 307         if (ret) {
 308                 dev_err(priv->dev,
 309                         "Unable to acquire IRQ %d\n", priv->irq);
 310                 return ret;
 311         }
 312
 313         switch (cp->type) {
 314         case IMX_MU_TYPE_RX:
 315                 imx_mu_xcr_rmw(priv, IMX_MU_xCR_RIEn(cp->idx), 0);
 316                 break;
 317         case IMX_MU_TYPE_RXDB:
 318                 imx_mu_xcr_rmw(priv, IMX_MU_xCR_GIEn(cp->idx), 0);
 319                 break;
 320         default:
 321                 break;
 322         }
 323
 324         return 0;
 325 }
 326
 327 static void imx_mu_shutdown(struct mbox_chan *chan)
 328 {
 329         struct imx_mu_priv *priv = to_imx_mu_priv(chan->mbox);
 330         struct imx_mu_con_priv *cp = chan->con_priv;
 331
 332         if (cp->type == IMX_MU_TYPE_TXDB) {
 333                 tasklet_kill(&cp->txdb_tasklet);
 334                 pm_runtime_put_sync(priv->dev);
 335                 return;
 336         }
 337
 338         switch (cp->type) {
 339         case IMX_MU_TYPE_TX:
 340                 imx_mu_xcr_rmw(priv, 0, IMX_MU_xCR_TIEn(cp->idx));
 341                 break;
 342         case IMX_MU_TYPE_RX:
 343                 imx_mu_xcr_rmw(priv, 0, IMX_MU_xCR_RIEn(cp->idx));
 344                 break;
 345         case IMX_MU_TYPE_RXDB:
 346                 imx_mu_xcr_rmw(priv, 0, IMX_MU_xCR_GIEn(cp->idx));
 347                 break;
 348         default:
 349                 break;
 350         }
 351
 352         free_irq(priv->irq, chan);
 353         pm_runtime_put_sync(priv->dev);
 354 }
 355
 356 static const struct mbox_chan_ops imx_mu_ops = {
 357         .send_data = imx_mu_send_data,
 358         .startup = imx_mu_startup,
 359         .shutdown = imx_mu_shutdown,
 360 };
 361
 362 static struct mbox_chan *imx_mu_scu_xlate(struct mbox_controller *mbox,
 363                                           const struct of_phandle_args *sp)
 364 {
 365         u32 type, idx, chan;
 366
 367         if (sp->args_count != 2) {
 368                 dev_err(mbox->dev, "Invalid argument count %d\n", sp->args_count);
 369                 return ERR_PTR(-EINVAL);
 370         }
 371
 372         type = sp->args[0]; /* channel type */
 373         idx = sp->args[1]; /* index */
 374
 375         switch (type) {
 376         case IMX_MU_TYPE_TX:
 377         case IMX_MU_TYPE_RX:
 378                 if (idx != 0)
 379                         dev_err(mbox->dev, "Invalid chan idx: %d\n", idx);
 380                 chan = type;
 381                 break;
 382         case IMX_MU_TYPE_RXDB:
 383                 chan = 2 + idx;
 384                 break;
 385         default:
 386                 dev_err(mbox->dev, "Invalid chan type: %d\n", type);
 387                 return ERR_PTR(-EINVAL);
 388         }
 389
 390         if (chan >= mbox->num_chans) {
 391                 dev_err(mbox->dev, "Not supported channel number: %d. (type: %d, idx: %d)\n", chan, type, idx);
 392                 return ERR_PTR(-EINVAL);
 393         }
 394
 395         return &mbox->chans[chan];
 396 }
 397
 398 static struct mbox_chan * imx_mu_xlate(struct mbox_controller *mbox,
 399                                        const struct of_phandle_args *sp)
 400 {
 401         u32 type, idx, chan;
 402
 403         if (sp->args_count != 2) {
 404                 dev_err(mbox->dev, "Invalid argument count %d\n", sp->args_count);
 405                 return ERR_PTR(-EINVAL);
 406         }
 407
 408         type = sp->args[0]; /* channel type */
 409         idx = sp->args[1]; /* index */
 410         chan = type * 4 + idx;
 411
 412         if (chan >= mbox->num_chans) {
 413                 dev_err(mbox->dev, "Not supported channel number: %d. (type: %d, idx: %d)\n", chan, type, idx);
 414                 return ERR_PTR(-EINVAL);
 415         }
 416
 417         return &mbox->chans[chan];
 418 }
 419
 420 static void imx_mu_init_generic(struct imx_mu_priv *priv)
 421 {
 422         unsigned int i;
 423
 424         for (i = 0; i < IMX_MU_CHANS; i++) {
 425                 struct imx_mu_con_priv *cp = &priv->con_priv[i];
 426
 427                 cp->idx = i % 4;
 428                 cp->type = i >> 2;
 429                 cp->chan = &priv->mbox_chans[i];
 430                 priv->mbox_chans[i].con_priv = cp;
 431                 snprintf(cp->irq_desc, sizeof(cp->irq_desc),
 432                          "imx_mu_chan[%i-%i]", cp->type, cp->idx);
 433         }
 434
 435         priv->mbox.num_chans = IMX_MU_CHANS;
 436         priv->mbox.of_xlate = imx_mu_xlate;
 437
 438         if (priv->side_b)
 439                 return;
 440
 441         /* Set default MU configuration */
 442         imx_mu_write(priv, 0, priv->dcfg->xCR);
 443 }
 444
 445 static void imx_mu_init_scu(struct imx_mu_priv *priv)
 446 {
 447         unsigned int i;
 448
 449         for (i = 0; i < IMX_MU_SCU_CHANS; i++) {
 450                 struct imx_mu_con_priv *cp = &priv->con_priv[i];
 451
 452                 cp->idx = i < 2 ? 0 : i - 2;
 453                 cp->type = i < 2 ? i : IMX_MU_TYPE_RXDB;
 454                 cp->chan = &priv->mbox_chans[i];
 455                 priv->mbox_chans[i].con_priv = cp;
 456                 snprintf(cp->irq_desc, sizeof(cp->irq_desc),
 457                          "imx_mu_chan[%i-%i]", cp->type, cp->idx);
 458         }
 459
 460         priv->mbox.num_chans = IMX_MU_SCU_CHANS;
 461         priv->mbox.of_xlate = imx_mu_scu_xlate;
 462
 463         /* Set default MU configuration */
 464         imx_mu_write(priv, 0, priv->dcfg->xCR);
 465 }
 466
 467 static int imx_mu_probe(struct platform_device *pdev)
 468 {
 469         struct device *dev = &pdev->dev;
 470         struct device_node *np = dev->of_node;
 471         struct imx_mu_priv *priv;
 472         const struct imx_mu_dcfg *dcfg;
 473         int ret;
 474
 475         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 476         if (!priv)
 477                 return -ENOMEM;
 478
 479         priv->dev = dev;
 480
 481         priv->base = devm_platform_ioremap_resource(pdev, 0);
 482         if (IS_ERR(priv->base))
 483                 return PTR_ERR(priv->base);
 484
 485         priv->irq = platform_get_irq(pdev, 0);
 486         if (priv->irq < 0)
 487                 return priv->irq;
 488
 489         dcfg = of_device_get_match_data(dev);
 490         if (!dcfg)
 491                 return -EINVAL;
 492         priv->dcfg = dcfg;
 493
 494         priv->clk = devm_clk_get(dev, NULL);
 495         if (IS_ERR(priv->clk)) {
 496                 if (PTR_ERR(priv->clk) != -ENOENT)
 497                         return PTR_ERR(priv->clk);
 498
 499                 priv->clk = NULL;
 500         }
 501
 502         ret = clk_prepare_enable(priv->clk);
 503         if (ret) {
 504                 dev_err(dev, "Failed to enable clock\n");
 505                 return ret;
 506         }
 507
 508         priv->side_b = of_property_read_bool(np, "fsl,mu-side-b");
 509
 510         priv->dcfg->init(priv);
 511
 512         spin_lock_init(&priv->xcr_lock);
 513
 514         priv->mbox.dev = dev;
 515         priv->mbox.ops = &imx_mu_ops;
 516         priv->mbox.chans = priv->mbox_chans;
 517         priv->mbox.txdone_irq = true;
 518
 519         platform_set_drvdata(pdev, priv);
 520
 521         ret = devm_mbox_controller_register(dev, &priv->mbox);
 522         if (ret) {
 523                 clk_disable_unprepare(priv->clk);
 524                 return ret;
 525         }
 526
 527         pm_runtime_enable(dev);
 528
 529         ret = pm_runtime_get_sync(dev);
 530         if (ret < 0) {
 531                 pm_runtime_put_noidle(dev);
 532                 goto disable_runtime_pm;
 533         }
 534
 535         ret = pm_runtime_put_sync(dev);
 536         if (ret < 0)
 537                 goto disable_runtime_pm;
 538
 539         clk_disable_unprepare(priv->clk);
 540
 541         return 0;
 542
 543 disable_runtime_pm:
 544         pm_runtime_disable(dev);
 545         clk_disable_unprepare(priv->clk);
 546         return ret;
 547 }
 548
 549 static int imx_mu_remove(struct platform_device *pdev)
 550 {
 551         struct imx_mu_priv *priv = platform_get_drvdata(pdev);
 552
 553         pm_runtime_disable(priv->dev);
 554
 555         return 0;
 556 }
 557
 558 static const struct imx_mu_dcfg imx_mu_cfg_imx6sx = {
 559         .tx     = imx_mu_generic_tx,
 560         .rx     = imx_mu_generic_rx,
 561         .init   = imx_mu_init_generic,
 562         .xTR    = {0x0, 0x4, 0x8, 0xc},
 563         .xRR    = {0x10, 0x14, 0x18, 0x1c},
 564         .xSR    = 0x20,
 565         .xCR    = 0x24,
 566 };
 567
 568 static const struct imx_mu_dcfg imx_mu_cfg_imx7ulp = {
 569         .tx     = imx_mu_generic_tx,
 570         .rx     = imx_mu_generic_rx,
 571         .init   = imx_mu_init_generic,
 572         .xTR    = {0x20, 0x24, 0x28, 0x2c},
 573         .xRR    = {0x40, 0x44, 0x48, 0x4c},
 574         .xSR    = 0x60,
 575         .xCR    = 0x64,
 576 };
 577
 578 static const struct imx_mu_dcfg imx_mu_cfg_imx8_scu = {
 579         .tx     = imx_mu_scu_tx,
 580         .rx     = imx_mu_scu_rx,
 581         .init   = imx_mu_init_scu,
 582         .xTR    = {0x0, 0x4, 0x8, 0xc},
 583         .xRR    = {0x10, 0x14, 0x18, 0x1c},
 584         .xSR    = 0x20,
 585         .xCR    = 0x24,
 586 };
 587
 588 static const struct of_device_id imx_mu_dt_ids[] = {
 589         { .compatible = "fsl,imx7ulp-mu", .data = &imx_mu_cfg_imx7ulp },
 590         { .compatible = "fsl,imx6sx-mu", .data = &imx_mu_cfg_imx6sx },
 591         { .compatible = "fsl,imx8-mu-scu", .data = &imx_mu_cfg_imx8_scu },
 592         { },
 593 };
 594 MODULE_DEVICE_TABLE(of, imx_mu_dt_ids);
 595
 596 static int imx_mu_suspend_noirq(struct device *dev)
 597 {
 598         struct imx_mu_priv *priv = dev_get_drvdata(dev);
 599
 600         if (!priv->clk)
 601                 priv->xcr = imx_mu_read(priv, priv->dcfg->xCR);
 602
 603         return 0;
 604 }
 605
 606 static int imx_mu_resume_noirq(struct device *dev)
 607 {
 608         struct imx_mu_priv *priv = dev_get_drvdata(dev);
 609
 610         /*
 611          * ONLY restore MU when context lost, the TIE could
 612          * be set during noirq resume as there is MU data
 613          * communication going on, and restore the saved
 614          * value will overwrite the TIE and cause MU data
 615          * send failed, may lead to system freeze. This issue
 616          * is observed by testing freeze mode suspend.
 617          */
 618         if (!imx_mu_read(priv, priv->dcfg->xCR) && !priv->clk)
 619                 imx_mu_write(priv, priv->xcr, priv->dcfg->xCR);
 620
 621         return 0;
 622 }
 623
 624 static int imx_mu_runtime_suspend(struct device *dev)
 625 {
 626         struct imx_mu_priv *priv = dev_get_drvdata(dev);
 627
 628         clk_disable_unprepare(priv->clk);
 629
 630         return 0;
 631 }
 632
 633 static int imx_mu_runtime_resume(struct device *dev)
 634 {
 635         struct imx_mu_priv *priv = dev_get_drvdata(dev);
 636         int ret;
 637
 638         ret = clk_prepare_enable(priv->clk);
 639         if (ret)
 640                 dev_err(dev, "failed to enable clock\n");
 641
 642         return ret;
 643 }
 644
 645 static const struct dev_pm_ops imx_mu_pm_ops = {
 646         SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(imx_mu_suspend_noirq,
 647                                       imx_mu_resume_noirq)
 648         SET_RUNTIME_PM_OPS(imx_mu_runtime_suspend,
 649                            imx_mu_runtime_resume, NULL)
 650 };
 651
 652 static struct platform_driver imx_mu_driver = {
 653         .probe          = imx_mu_probe,
 654         .remove         = imx_mu_remove,
 655         .driver = {
 656                 .name   = "imx_mu",
 657                 .of_match_table = imx_mu_dt_ids,
 658                 .pm = &imx_mu_pm_ops,
 659         },
 660 };
 661 module_platform_driver(imx_mu_driver);
 662
 663 MODULE_AUTHOR("Oleksij Rempel <o.rempel@pengutronix.de>");
 664 MODULE_DESCRIPTION("Message Unit driver for i.MX");
 665 MODULE_LICENSE("GPL v2");