arch/powerpc/platforms/512x/mpc512x_lpbfifo.c

   1 /*
   2  * The driver for Freescale MPC512x LocalPlus Bus FIFO
   3  * (called SCLPC in the Reference Manual).
   4  *
   5  * Copyright (C) 2013-2015 Alexander Popov <alex.popov@linux.com>.
   6  *
   7  * This file is released under the GPLv2.
   8  */
   9
  10 #include <linux/interrupt.h>
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/of.h>
  14 #include <linux/of_platform.h>
  15 #include <linux/of_address.h>
  16 #include <linux/of_irq.h>
  17 #include <asm/mpc5121.h>
  18 #include <asm/io.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/slab.h>
  21 #include <linux/dmaengine.h>
  22 #include <linux/dma-direction.h>
  23 #include <linux/dma-mapping.h>
  24
  25 #define DRV_NAME "mpc512x_lpbfifo"
  26
  27 struct cs_range {
  28         u32 csnum;
  29         u32 base; /* must be zero */
  30         u32 addr;
  31         u32 size;
  32 };
  33
  34 static struct lpbfifo_data {
  35         spinlock_t lock; /* for protecting lpbfifo_data */
  36         phys_addr_t regs_phys;
  37         resource_size_t regs_size;
  38         struct mpc512x_lpbfifo __iomem *regs;
  39         int irq;
  40         struct cs_range *cs_ranges;
  41         size_t cs_n;
  42         struct dma_chan *chan;
  43         struct mpc512x_lpbfifo_request *req;
  44         dma_addr_t ram_bus_addr;
  45         bool wait_lpbfifo_irq;
  46         bool wait_lpbfifo_callback;
  47 } lpbfifo;
  48
  49 /*
  50  * A data transfer from RAM to some device on LPB is finished
  51  * when both mpc512x_lpbfifo_irq() and mpc512x_lpbfifo_callback()
  52  * have been called. We execute the callback registered in
  53  * mpc512x_lpbfifo_request just after that.
  54  * But for a data transfer from some device on LPB to RAM we don't enable
  55  * LPBFIFO interrupt because clearing MPC512X_SCLPC_SUCCESS interrupt flag
  56  * automatically disables LPBFIFO reading request to the DMA controller
  57  * and the data transfer hangs. So the callback registered in
  58  * mpc512x_lpbfifo_request is executed at the end of mpc512x_lpbfifo_callback().
  59  */
  60
  61 /*
  62  * mpc512x_lpbfifo_irq - IRQ handler for LPB FIFO
  63  */
  64 static irqreturn_t mpc512x_lpbfifo_irq(int irq, void *param)
  65 {
  66         struct device *dev = (struct device *)param;
  67         struct mpc512x_lpbfifo_request *req = NULL;
  68         unsigned long flags;
  69         u32 status;
  70
  71         spin_lock_irqsave(&lpbfifo.lock, flags);
  72
  73         if (!lpbfifo.regs)
  74                 goto end;
  75
  76         req = lpbfifo.req;
  77         if (!req || req->dir == MPC512X_LPBFIFO_REQ_DIR_READ) {
  78                 dev_err(dev, "bogus LPBFIFO IRQ\n");
  79                 goto end;
  80         }
  81
  82         status = in_be32(&lpbfifo.regs->status);
  83         if (status != MPC512X_SCLPC_SUCCESS) {
  84                 dev_err(dev, "DMA transfer from RAM to peripheral failed\n");
  85                 out_be32(&lpbfifo.regs->enable,
  86                                 MPC512X_SCLPC_RESET | MPC512X_SCLPC_FIFO_RESET);
  87                 goto end;
  88         }
  89         /* Clear the interrupt flag */
  90         out_be32(&lpbfifo.regs->status, MPC512X_SCLPC_SUCCESS);
  91
  92         lpbfifo.wait_lpbfifo_irq = false;
  93
  94         if (lpbfifo.wait_lpbfifo_callback)
  95                 goto end;
  96
  97         /* Transfer is finished, set the FIFO as idle */
  98         lpbfifo.req = NULL;
  99
 100         spin_unlock_irqrestore(&lpbfifo.lock, flags);
 101
 102         if (req->callback)
 103                 req->callback(req);
 104
 105         return IRQ_HANDLED;
 106
 107  end:
 108         spin_unlock_irqrestore(&lpbfifo.lock, flags);
 109         return IRQ_HANDLED;
 110 }
 111
 112 /*
 113  * mpc512x_lpbfifo_callback is called by DMA driver when
 114  * DMA transaction is finished.
 115  */
 116 static void mpc512x_lpbfifo_callback(void *param)
 117 {
 118         unsigned long flags;
 119         struct mpc512x_lpbfifo_request *req = NULL;
 120         enum dma_data_direction dir;
 121
 122         spin_lock_irqsave(&lpbfifo.lock, flags);
 123
 124         if (!lpbfifo.regs) {
 125                 spin_unlock_irqrestore(&lpbfifo.lock, flags);
 126                 return;
 127         }
 128
 129         req = lpbfifo.req;
 130         if (!req) {
 131                 pr_err("bogus LPBFIFO callback\n");
 132                 spin_unlock_irqrestore(&lpbfifo.lock, flags);
 133                 return;
 134         }
 135
 136         /* Release the mapping */
 137         if (req->dir == MPC512X_LPBFIFO_REQ_DIR_WRITE)
 138                 dir = DMA_TO_DEVICE;
 139         else
 140                 dir = DMA_FROM_DEVICE;
 141         dma_unmap_single(lpbfifo.chan->device->dev,
 142                         lpbfifo.ram_bus_addr, req->size, dir);
 143
 144         lpbfifo.wait_lpbfifo_callback = false;
 145
 146         if (!lpbfifo.wait_lpbfifo_irq) {
 147                 /* Transfer is finished, set the FIFO as idle */
 148                 lpbfifo.req = NULL;
 149
 150                 spin_unlock_irqrestore(&lpbfifo.lock, flags);
 151
 152                 if (req->callback)
 153                         req->callback(req);
 154         } else {
 155                 spin_unlock_irqrestore(&lpbfifo.lock, flags);
 156         }
 157 }
 158
 159 static int mpc512x_lpbfifo_kick(void)
 160 {
 161         u32 bits;
 162         bool no_incr = false;
 163         u32 bpt = 32; /* max bytes per LPBFIFO transaction involving DMA */
 164         u32 cs = 0;
 165         size_t i;
 166         struct dma_device *dma_dev = NULL;
 167         struct scatterlist sg;
 168         enum dma_data_direction dir;
 169         struct dma_slave_config dma_conf = {};
 170         struct dma_async_tx_descriptor *dma_tx = NULL;
 171         dma_cookie_t cookie;
 172         int ret;
 173
 174         /*
 175          * 1. Fit the requirements:
 176          * - the packet size must be a multiple of 4 since FIFO Data Word
 177          *    Register allows only full-word access according the Reference
 178          *    Manual;
 179          * - the physical address of the device on LPB and the packet size
 180          *    must be aligned on BPT (bytes per transaction) or 8-bytes
 181          *    boundary according the Reference Manual;
 182          * - but we choose DMA maxburst equal (or very close to) BPT to prevent
 183          *    DMA controller from overtaking FIFO and causing FIFO underflow
 184          *    error. So we force the packet size to be aligned on BPT boundary
 185          *    not to confuse DMA driver which requires the packet size to be
 186          *    aligned on maxburst boundary;
 187          * - BPT should be set to the LPB device port size for operation with
 188          *    disabled auto-incrementing according Reference Manual.
 189          */
 190         if (lpbfifo.req->size == 0 || !IS_ALIGNED(lpbfifo.req->size, 4))
 191                 return -EINVAL;
 192
 193         if (lpbfifo.req->portsize != LPB_DEV_PORTSIZE_UNDEFINED) {
 194                 bpt = lpbfifo.req->portsize;
 195                 no_incr = true;
 196         }
 197
 198         while (bpt > 1) {
 199                 if (IS_ALIGNED(lpbfifo.req->dev_phys_addr, min(bpt, 0x8u)) &&
 200                                         IS_ALIGNED(lpbfifo.req->size, bpt)) {
 201                         break;
 202                 }
 203
 204                 if (no_incr)
 205                         return -EINVAL;
 206
 207                 bpt >>= 1;
 208         }
 209         dma_conf.dst_maxburst = max(bpt, 0x4u) / 4;
 210         dma_conf.src_maxburst = max(bpt, 0x4u) / 4;
 211
 212         for (i = 0; i < lpbfifo.cs_n; i++) {
 213                 phys_addr_t cs_start = lpbfifo.cs_ranges[i].addr;
 214                 phys_addr_t cs_end = cs_start + lpbfifo.cs_ranges[i].size;
 215                 phys_addr_t access_start = lpbfifo.req->dev_phys_addr;
 216                 phys_addr_t access_end = access_start + lpbfifo.req->size;
 217
 218                 if (access_start >= cs_start && access_end <= cs_end) {
 219                         cs = lpbfifo.cs_ranges[i].csnum;
 220                         break;
 221                 }
 222         }
 223         if (i == lpbfifo.cs_n)
 224                 return -EFAULT;
 225
 226         /* 2. Prepare DMA */
 227         dma_dev = lpbfifo.chan->device;
 228
 229         if (lpbfifo.req->dir == MPC512X_LPBFIFO_REQ_DIR_WRITE) {
 230                 dir = DMA_TO_DEVICE;
 231                 dma_conf.direction = DMA_MEM_TO_DEV;
 232                 dma_conf.dst_addr = lpbfifo.regs_phys +
 233                                 offsetof(struct mpc512x_lpbfifo, data_word);
 234         } else {
 235                 dir = DMA_FROM_DEVICE;
 236                 dma_conf.direction = DMA_DEV_TO_MEM;
 237                 dma_conf.src_addr = lpbfifo.regs_phys +
 238                                 offsetof(struct mpc512x_lpbfifo, data_word);
 239         }
 240         dma_conf.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
 241         dma_conf.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
 242
 243         /* Make DMA channel work with LPB FIFO data register */
 244         if (dma_dev->device_config(lpbfifo.chan, &dma_conf)) {
 245                 ret = -EINVAL;
 246                 goto err_dma_prep;
 247         }
 248
 249         sg_init_table(&sg, 1);
 250
 251         sg_dma_address(&sg) = dma_map_single(dma_dev->dev,
 252                         lpbfifo.req->ram_virt_addr, lpbfifo.req->size, dir);
 253         if (dma_mapping_error(dma_dev->dev, sg_dma_address(&sg)))
 254                 return -EFAULT;
 255
 256         lpbfifo.ram_bus_addr = sg_dma_address(&sg); /* For freeing later */
 257
 258         sg_dma_len(&sg) = lpbfifo.req->size;
 259
 260         dma_tx = dmaengine_prep_slave_sg(lpbfifo.chan, &sg,
 261                                                 1, dma_conf.direction, 0);
 262         if (!dma_tx) {
 263                 ret = -ENOSPC;
 264                 goto err_dma_prep;
 265         }
 266         dma_tx->callback = mpc512x_lpbfifo_callback;
 267         dma_tx->callback_param = NULL;
 268
 269         /* 3. Prepare FIFO */
 270         out_be32(&lpbfifo.regs->enable,
 271                                 MPC512X_SCLPC_RESET | MPC512X_SCLPC_FIFO_RESET);
 272         out_be32(&lpbfifo.regs->enable, 0x0);
 273
 274         /*
 275          * Configure the watermarks for write operation (RAM->DMA->FIFO->dev):
 276          * - high watermark 7 words according the Reference Manual,
 277          * - low watermark 512 bytes (half of the FIFO).
 278          * These watermarks don't work for read operation since the
 279          * MPC512X_SCLPC_FLUSH bit is set (according the Reference Manual).
 280          */
 281         out_be32(&lpbfifo.regs->fifo_ctrl, MPC512X_SCLPC_FIFO_CTRL(0x7));
 282         out_be32(&lpbfifo.regs->fifo_alarm, MPC512X_SCLPC_FIFO_ALARM(0x200));
 283
 284         /*
 285          * Start address is a physical address of the region which belongs
 286          * to the device on the LocalPlus Bus
 287          */
 288         out_be32(&lpbfifo.regs->start_addr, lpbfifo.req->dev_phys_addr);
 289
 290         /*
 291          * Configure chip select, transfer direction, address increment option
 292          * and bytes per transaction option
 293          */
 294         bits = MPC512X_SCLPC_CS(cs);
 295         if (lpbfifo.req->dir == MPC512X_LPBFIFO_REQ_DIR_READ)
 296                 bits |= MPC512X_SCLPC_READ | MPC512X_SCLPC_FLUSH;
 297         if (no_incr)
 298                 bits |= MPC512X_SCLPC_DAI;
 299         bits |= MPC512X_SCLPC_BPT(bpt);
 300         out_be32(&lpbfifo.regs->ctrl, bits);
 301
 302         /* Unmask irqs */
 303         bits = MPC512X_SCLPC_ENABLE | MPC512X_SCLPC_ABORT_INT_ENABLE;
 304         if (lpbfifo.req->dir == MPC512X_LPBFIFO_REQ_DIR_WRITE)
 305                 bits |= MPC512X_SCLPC_NORM_INT_ENABLE;
 306         else
 307                 lpbfifo.wait_lpbfifo_irq = false;
 308
 309         out_be32(&lpbfifo.regs->enable, bits);
 310
 311         /* 4. Set packet size and kick FIFO off */
 312         bits = lpbfifo.req->size | MPC512X_SCLPC_START;
 313         out_be32(&lpbfifo.regs->pkt_size, bits);
 314
 315         /* 5. Finally kick DMA off */
 316         cookie = dma_tx->tx_submit(dma_tx);
 317         if (dma_submit_error(cookie)) {
 318                 ret = -ENOSPC;
 319                 goto err_dma_submit;
 320         }
 321
 322         return 0;
 323
 324  err_dma_submit:
 325         out_be32(&lpbfifo.regs->enable,
 326                                 MPC512X_SCLPC_RESET | MPC512X_SCLPC_FIFO_RESET);
 327  err_dma_prep:
 328         dma_unmap_single(dma_dev->dev, sg_dma_address(&sg),
 329                                                 lpbfifo.req->size, dir);
 330         return ret;
 331 }
 332
 333 static int mpc512x_lpbfifo_submit_locked(struct mpc512x_lpbfifo_request *req)
 334 {
 335         int ret = 0;
 336
 337         if (!lpbfifo.regs)
 338                 return -ENODEV;
 339
 340         /* Check whether a transfer is in progress */
 341         if (lpbfifo.req)
 342                 return -EBUSY;
 343
 344         lpbfifo.wait_lpbfifo_irq = true;
 345         lpbfifo.wait_lpbfifo_callback = true;
 346         lpbfifo.req = req;
 347
 348         ret = mpc512x_lpbfifo_kick();
 349         if (ret != 0)
 350                 lpbfifo.req = NULL; /* Set the FIFO as idle */
 351
 352         return ret;
 353 }
 354
 355 int mpc512x_lpbfifo_submit(struct mpc512x_lpbfifo_request *req)
 356 {
 357         unsigned long flags;
 358         int ret = 0;
 359
 360         spin_lock_irqsave(&lpbfifo.lock, flags);
 361         ret = mpc512x_lpbfifo_submit_locked(req);
 362         spin_unlock_irqrestore(&lpbfifo.lock, flags);
 363
 364         return ret;
 365 }
 366 EXPORT_SYMBOL(mpc512x_lpbfifo_submit);
 367
 368 /*
 369  * LPBFIFO driver uses "ranges" property of "localbus" device tree node
 370  * for being able to determine the chip select number of a client device
 371  * ordering a DMA transfer.
 372  */
 373 static int get_cs_ranges(struct device *dev)
 374 {
 375         int ret = -ENODEV;
 376         struct device_node *lb_node;
 377         const u32 *addr_cells_p;
 378         const u32 *size_cells_p;
 379         int proplen;
 380         size_t i;
 381
 382         lb_node = of_find_compatible_node(NULL, NULL, "fsl,mpc5121-localbus");
 383         if (!lb_node)
 384                 return ret;
 385
 386         /*
 387          * The node defined as compatible with 'fsl,mpc5121-localbus'
 388          * should have two address cells and one size cell.
 389          * Every item of its ranges property should consist of:
 390          * - the first address cell which is the chipselect number;
 391          * - the second address cell which is the offset in the chipselect,
 392          *    must be zero.
 393          * - CPU address of the beginning of an access window;
 394          * - the only size cell which is the size of an access window.
 395          */
 396         addr_cells_p = of_get_property(lb_node, "#address-cells", NULL);
 397         size_cells_p = of_get_property(lb_node, "#size-cells", NULL);
 398         if (addr_cells_p == NULL || *addr_cells_p != 2 ||
 399                                 size_cells_p == NULL || *size_cells_p != 1) {
 400                 goto end;
 401         }
 402
 403         proplen = of_property_count_u32_elems(lb_node, "ranges");
 404         if (proplen <= 0 || proplen % 4 != 0)
 405                 goto end;
 406
 407         lpbfifo.cs_n = proplen / 4;
 408         lpbfifo.cs_ranges = devm_kcalloc(dev, lpbfifo.cs_n,
 409                                         sizeof(struct cs_range), GFP_KERNEL);
 410         if (!lpbfifo.cs_ranges)
 411                 goto end;
 412
 413         if (of_property_read_u32_array(lb_node, "ranges",
 414                                 (u32 *)lpbfifo.cs_ranges, proplen) != 0) {
 415                 goto end;
 416         }
 417
 418         for (i = 0; i < lpbfifo.cs_n; i++) {
 419                 if (lpbfifo.cs_ranges[i].base != 0)
 420                         goto end;
 421         }
 422
 423         ret = 0;
 424
 425  end:
 426         of_node_put(lb_node);
 427         return ret;
 428 }
 429
 430 static int mpc512x_lpbfifo_probe(struct platform_device *pdev)
 431 {
 432         struct resource r;
 433         int ret = 0;
 434
 435         memset(&lpbfifo, 0, sizeof(struct lpbfifo_data));
 436         spin_lock_init(&lpbfifo.lock);
 437
 438         lpbfifo.chan = dma_request_slave_channel(&pdev->dev, "rx-tx");
 439         if (lpbfifo.chan == NULL)
 440                 return -EPROBE_DEFER;
 441
 442         if (of_address_to_resource(pdev->dev.of_node, 0, &r) != 0) {
 443                 dev_err(&pdev->dev, "bad 'reg' in 'sclpc' device tree node\n");
 444                 ret = -ENODEV;
 445                 goto err0;
 446         }
 447
 448         lpbfifo.regs_phys = r.start;
 449         lpbfifo.regs_size = resource_size(&r);
 450
 451         if (!devm_request_mem_region(&pdev->dev, lpbfifo.regs_phys,
 452                                         lpbfifo.regs_size, DRV_NAME)) {
 453                 dev_err(&pdev->dev, "unable to request region\n");
 454                 ret = -EBUSY;
 455                 goto err0;
 456         }
 457
 458         lpbfifo.regs = devm_ioremap(&pdev->dev,
 459                                         lpbfifo.regs_phys, lpbfifo.regs_size);
 460         if (!lpbfifo.regs) {
 461                 dev_err(&pdev->dev, "mapping registers failed\n");
 462                 ret = -ENOMEM;
 463                 goto err0;
 464         }
 465
 466         out_be32(&lpbfifo.regs->enable,
 467                                 MPC512X_SCLPC_RESET | MPC512X_SCLPC_FIFO_RESET);
 468
 469         if (get_cs_ranges(&pdev->dev) != 0) {
 470                 dev_err(&pdev->dev, "bad '/localbus' device tree node\n");
 471                 ret = -ENODEV;
 472                 goto err0;
 473         }
 474
 475         lpbfifo.irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
 476         if (lpbfifo.irq == NO_IRQ) {
 477                 dev_err(&pdev->dev, "mapping irq failed\n");
 478                 ret = -ENODEV;
 479                 goto err0;
 480         }
 481
 482         if (request_irq(lpbfifo.irq, mpc512x_lpbfifo_irq, 0,
 483                                                 DRV_NAME, &pdev->dev) != 0) {
 484                 dev_err(&pdev->dev, "requesting irq failed\n");
 485                 ret = -ENODEV;
 486                 goto err1;
 487         }
 488
 489         dev_info(&pdev->dev, "probe succeeded\n");
 490         return 0;
 491
 492  err1:
 493         irq_dispose_mapping(lpbfifo.irq);
 494  err0:
 495         dma_release_channel(lpbfifo.chan);
 496         return ret;
 497 }
 498
 499 static int mpc512x_lpbfifo_remove(struct platform_device *pdev)
 500 {
 501         unsigned long flags;
 502         struct dma_device *dma_dev = lpbfifo.chan->device;
 503         struct mpc512x_lpbfifo __iomem *regs = NULL;
 504
 505         spin_lock_irqsave(&lpbfifo.lock, flags);
 506         regs = lpbfifo.regs;
 507         lpbfifo.regs = NULL;
 508         spin_unlock_irqrestore(&lpbfifo.lock, flags);
 509
 510         dma_dev->device_terminate_all(lpbfifo.chan);
 511         out_be32(&regs->enable, MPC512X_SCLPC_RESET | MPC512X_SCLPC_FIFO_RESET);
 512
 513         free_irq(lpbfifo.irq, &pdev->dev);
 514         irq_dispose_mapping(lpbfifo.irq);
 515         dma_release_channel(lpbfifo.chan);
 516
 517         return 0;
 518 }
 519
 520 static const struct of_device_id mpc512x_lpbfifo_match[] = {
 521         { .compatible = "fsl,mpc512x-lpbfifo", },
 522         {},
 523 };
 524 MODULE_DEVICE_TABLE(of, mpc512x_lpbfifo_match);
 525
 526 static struct platform_driver mpc512x_lpbfifo_driver = {
 527         .probe = mpc512x_lpbfifo_probe,
 528         .remove = mpc512x_lpbfifo_remove,
 529         .driver = {
 530                 .name = DRV_NAME,
 531                 .owner = THIS_MODULE,
 532                 .of_match_table = mpc512x_lpbfifo_match,
 533         },
 534 };
 535
 536 module_platform_driver(mpc512x_lpbfifo_driver);
 537
 538 MODULE_AUTHOR("Alexander Popov <alex.popov@linux.com>");
 539 MODULE_DESCRIPTION("MPC512x LocalPlus Bus FIFO device driver");
 540 MODULE_LICENSE("GPL v2");