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

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * The driver for Freescale MPC512x LocalPlus Bus FIFO
   4  * (called SCLPC in the Reference Manual).
   5  *
   6  * Copyright (C) 2013-2015 Alexander Popov <alex.popov@linux.com>.
   7  */
   8
   9 #include <linux/interrupt.h>
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/of.h>
  13 #include <linux/of_platform.h>
  14 #include <linux/of_address.h>
  15 #include <linux/of_irq.h>
  16 #include <asm/mpc5121.h>
  17 #include <asm/io.h>
  18 #include <linux/spinlock.h>
  19 #include <linux/slab.h>
  20 #include <linux/dmaengine.h>
  21 #include <linux/dma-direction.h>
  22 #include <linux/dma-mapping.h>
  23
  24 #define DRV_NAME "mpc512x_lpbfifo"
  25
  26 struct cs_range {
  27         u32 csnum;
  28         u32 base; /* must be zero */
  29         u32 addr;
  30         u32 size;
  31 };
  32
  33 static struct lpbfifo_data {
  34         spinlock_t lock; /* for protecting lpbfifo_data */
  35         phys_addr_t regs_phys;
  36         resource_size_t regs_size;
  37         struct mpc512x_lpbfifo __iomem *regs;
  38         int irq;
  39         struct cs_range *cs_ranges;
  40         size_t cs_n;
  41         struct dma_chan *chan;
  42         struct mpc512x_lpbfifo_request *req;
  43         dma_addr_t ram_bus_addr;
  44         bool wait_lpbfifo_irq;
  45         bool wait_lpbfifo_callback;
  46 } lpbfifo;
  47
  48 /*
  49  * A data transfer from RAM to some device on LPB is finished
  50  * when both mpc512x_lpbfifo_irq() and mpc512x_lpbfifo_callback()
  51  * have been called. We execute the callback registered in
  52  * mpc512x_lpbfifo_request just after that.
  53  * But for a data transfer from some device on LPB to RAM we don't enable
  54  * LPBFIFO interrupt because clearing MPC512X_SCLPC_SUCCESS interrupt flag
  55  * automatically disables LPBFIFO reading request to the DMA controller
  56  * and the data transfer hangs. So the callback registered in
  57  * mpc512x_lpbfifo_request is executed at the end of mpc512x_lpbfifo_callback().
  58  */
  59
  60 /*
  61  * mpc512x_lpbfifo_irq - IRQ handler for LPB FIFO
  62  */
  63 static irqreturn_t mpc512x_lpbfifo_irq(int irq, void *param)
  64 {
  65         struct device *dev = (struct device *)param;
  66         struct mpc512x_lpbfifo_request *req = NULL;
  67         unsigned long flags;
  68         u32 status;
  69
  70         spin_lock_irqsave(&lpbfifo.lock, flags);
  71
  72         if (!lpbfifo.regs)
  73                 goto end;
  74
  75         req = lpbfifo.req;
  76         if (!req || req->dir == MPC512X_LPBFIFO_REQ_DIR_READ) {
  77                 dev_err(dev, "bogus LPBFIFO IRQ\n");
  78                 goto end;
  79         }
  80
  81         status = in_be32(&lpbfifo.regs->status);
  82         if (status != MPC512X_SCLPC_SUCCESS) {
  83                 dev_err(dev, "DMA transfer from RAM to peripheral failed\n");
  84                 out_be32(&lpbfifo.regs->enable,
  85                                 MPC512X_SCLPC_RESET | MPC512X_SCLPC_FIFO_RESET);
  86                 goto end;
  87         }
  88         /* Clear the interrupt flag */
  89         out_be32(&lpbfifo.regs->status, MPC512X_SCLPC_SUCCESS);
  90
  91         lpbfifo.wait_lpbfifo_irq = false;
  92
  93         if (lpbfifo.wait_lpbfifo_callback)
  94                 goto end;
  95
  96         /* Transfer is finished, set the FIFO as idle */
  97         lpbfifo.req = NULL;
  98
  99         spin_unlock_irqrestore(&lpbfifo.lock, flags);
 100
 101         if (req->callback)
 102                 req->callback(req);
 103
 104         return IRQ_HANDLED;
 105
 106  end:
 107         spin_unlock_irqrestore(&lpbfifo.lock, flags);
 108         return IRQ_HANDLED;
 109 }
 110
 111 /*
 112  * mpc512x_lpbfifo_callback is called by DMA driver when
 113  * DMA transaction is finished.
 114  */
 115 static void mpc512x_lpbfifo_callback(void *param)
 116 {
 117         unsigned long flags;
 118         struct mpc512x_lpbfifo_request *req = NULL;
 119         enum dma_data_direction dir;
 120
 121         spin_lock_irqsave(&lpbfifo.lock, flags);
 122
 123         if (!lpbfifo.regs) {
 124                 spin_unlock_irqrestore(&lpbfifo.lock, flags);
 125                 return;
 126         }
 127
 128         req = lpbfifo.req;
 129         if (!req) {
 130                 pr_err("bogus LPBFIFO callback\n");
 131                 spin_unlock_irqrestore(&lpbfifo.lock, flags);
 132                 return;
 133         }
 134
 135         /* Release the mapping */
 136         if (req->dir == MPC512X_LPBFIFO_REQ_DIR_WRITE)
 137                 dir = DMA_TO_DEVICE;
 138         else
 139                 dir = DMA_FROM_DEVICE;
 140         dma_unmap_single(lpbfifo.chan->device->dev,
 141                         lpbfifo.ram_bus_addr, req->size, dir);
 142
 143         lpbfifo.wait_lpbfifo_callback = false;
 144
 145         if (!lpbfifo.wait_lpbfifo_irq) {
 146                 /* Transfer is finished, set the FIFO as idle */
 147                 lpbfifo.req = NULL;
 148
 149                 spin_unlock_irqrestore(&lpbfifo.lock, flags);
 150
 151                 if (req->callback)
 152                         req->callback(req);
 153         } else {
 154                 spin_unlock_irqrestore(&lpbfifo.lock, flags);
 155         }
 156 }
 157
 158 static int mpc512x_lpbfifo_kick(void)
 159 {
 160         u32 bits;
 161         bool no_incr = false;
 162         u32 bpt = 32; /* max bytes per LPBFIFO transaction involving DMA */
 163         u32 cs = 0;
 164         size_t i;
 165         struct dma_device *dma_dev = NULL;
 166         struct scatterlist sg;
 167         enum dma_data_direction dir;
 168         struct dma_slave_config dma_conf = {};
 169         struct dma_async_tx_descriptor *dma_tx = NULL;
 170         dma_cookie_t cookie;
 171         int ret;
 172
 173         /*
 174          * 1. Fit the requirements:
 175          * - the packet size must be a multiple of 4 since FIFO Data Word
 176          *    Register allows only full-word access according the Reference
 177          *    Manual;
 178          * - the physical address of the device on LPB and the packet size
 179          *    must be aligned on BPT (bytes per transaction) or 8-bytes
 180          *    boundary according the Reference Manual;
 181          * - but we choose DMA maxburst equal (or very close to) BPT to prevent
 182          *    DMA controller from overtaking FIFO and causing FIFO underflow
 183          *    error. So we force the packet size to be aligned on BPT boundary
 184          *    not to confuse DMA driver which requires the packet size to be
 185          *    aligned on maxburst boundary;
 186          * - BPT should be set to the LPB device port size for operation with
 187          *    disabled auto-incrementing according Reference Manual.
 188          */
 189         if (lpbfifo.req->size == 0 || !IS_ALIGNED(lpbfifo.req->size, 4))
 190                 return -EINVAL;
 191
 192         if (lpbfifo.req->portsize != LPB_DEV_PORTSIZE_UNDEFINED) {
 193                 bpt = lpbfifo.req->portsize;
 194                 no_incr = true;
 195         }
 196
 197         while (bpt > 1) {
 198                 if (IS_ALIGNED(lpbfifo.req->dev_phys_addr, min(bpt, 0x8u)) &&
 199                                         IS_ALIGNED(lpbfifo.req->size, bpt)) {
 200                         break;
 201                 }
 202
 203                 if (no_incr)
 204                         return -EINVAL;
 205
 206                 bpt >>= 1;
 207         }
 208         dma_conf.dst_maxburst = max(bpt, 0x4u) / 4;
 209         dma_conf.src_maxburst = max(bpt, 0x4u) / 4;
 210
 211         for (i = 0; i < lpbfifo.cs_n; i++) {
 212                 phys_addr_t cs_start = lpbfifo.cs_ranges[i].addr;
 213                 phys_addr_t cs_end = cs_start + lpbfifo.cs_ranges[i].size;
 214                 phys_addr_t access_start = lpbfifo.req->dev_phys_addr;
 215                 phys_addr_t access_end = access_start + lpbfifo.req->size;
 216
 217                 if (access_start >= cs_start && access_end <= cs_end) {
 218                         cs = lpbfifo.cs_ranges[i].csnum;
 219                         break;
 220                 }
 221         }
 222         if (i == lpbfifo.cs_n)
 223                 return -EFAULT;
 224
 225         /* 2. Prepare DMA */
 226         dma_dev = lpbfifo.chan->device;
 227
 228         if (lpbfifo.req->dir == MPC512X_LPBFIFO_REQ_DIR_WRITE) {
 229                 dir = DMA_TO_DEVICE;
 230                 dma_conf.direction = DMA_MEM_TO_DEV;
 231                 dma_conf.dst_addr = lpbfifo.regs_phys +
 232                                 offsetof(struct mpc512x_lpbfifo, data_word);
 233         } else {
 234                 dir = DMA_FROM_DEVICE;
 235                 dma_conf.direction = DMA_DEV_TO_MEM;
 236                 dma_conf.src_addr = lpbfifo.regs_phys +
 237                                 offsetof(struct mpc512x_lpbfifo, data_word);
 238         }
 239         dma_conf.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
 240         dma_conf.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
 241
 242         /* Make DMA channel work with LPB FIFO data register */
 243         if (dma_dev->device_config(lpbfifo.chan, &dma_conf)) {
 244                 ret = -EINVAL;
 245                 goto err_dma_prep;
 246         }
 247
 248         sg_init_table(&sg, 1);
 249
 250         sg_dma_address(&sg) = dma_map_single(dma_dev->dev,
 251                         lpbfifo.req->ram_virt_addr, lpbfifo.req->size, dir);
 252         if (dma_mapping_error(dma_dev->dev, sg_dma_address(&sg)))
 253                 return -EFAULT;
 254
 255         lpbfifo.ram_bus_addr = sg_dma_address(&sg); /* For freeing later */
 256
 257         sg_dma_len(&sg) = lpbfifo.req->size;
 258
 259         dma_tx = dmaengine_prep_slave_sg(lpbfifo.chan, &sg,
 260                                                 1, dma_conf.direction, 0);
 261         if (!dma_tx) {
 262                 ret = -ENOSPC;
 263                 goto err_dma_prep;
 264         }
 265         dma_tx->callback = mpc512x_lpbfifo_callback;
 266         dma_tx->callback_param = NULL;
 267
 268         /* 3. Prepare FIFO */
 269         out_be32(&lpbfifo.regs->enable,
 270                                 MPC512X_SCLPC_RESET | MPC512X_SCLPC_FIFO_RESET);
 271         out_be32(&lpbfifo.regs->enable, 0x0);
 272
 273         /*
 274          * Configure the watermarks for write operation (RAM->DMA->FIFO->dev):
 275          * - high watermark 7 words according the Reference Manual,
 276          * - low watermark 512 bytes (half of the FIFO).
 277          * These watermarks don't work for read operation since the
 278          * MPC512X_SCLPC_FLUSH bit is set (according the Reference Manual).
 279          */
 280         out_be32(&lpbfifo.regs->fifo_ctrl, MPC512X_SCLPC_FIFO_CTRL(0x7));
 281         out_be32(&lpbfifo.regs->fifo_alarm, MPC512X_SCLPC_FIFO_ALARM(0x200));
 282
 283         /*
 284          * Start address is a physical address of the region which belongs
 285          * to the device on the LocalPlus Bus
 286          */
 287         out_be32(&lpbfifo.regs->start_addr, lpbfifo.req->dev_phys_addr);
 288
 289         /*
 290          * Configure chip select, transfer direction, address increment option
 291          * and bytes per transaction option
 292          */
 293         bits = MPC512X_SCLPC_CS(cs);
 294         if (lpbfifo.req->dir == MPC512X_LPBFIFO_REQ_DIR_READ)
 295                 bits |= MPC512X_SCLPC_READ | MPC512X_SCLPC_FLUSH;
 296         if (no_incr)
 297                 bits |= MPC512X_SCLPC_DAI;
 298         bits |= MPC512X_SCLPC_BPT(bpt);
 299         out_be32(&lpbfifo.regs->ctrl, bits);
 300
 301         /* Unmask irqs */
 302         bits = MPC512X_SCLPC_ENABLE | MPC512X_SCLPC_ABORT_INT_ENABLE;
 303         if (lpbfifo.req->dir == MPC512X_LPBFIFO_REQ_DIR_WRITE)
 304                 bits |= MPC512X_SCLPC_NORM_INT_ENABLE;
 305         else
 306                 lpbfifo.wait_lpbfifo_irq = false;
 307
 308         out_be32(&lpbfifo.regs->enable, bits);
 309
 310         /* 4. Set packet size and kick FIFO off */
 311         bits = lpbfifo.req->size | MPC512X_SCLPC_START;
 312         out_be32(&lpbfifo.regs->pkt_size, bits);
 313
 314         /* 5. Finally kick DMA off */
 315         cookie = dma_tx->tx_submit(dma_tx);
 316         if (dma_submit_error(cookie)) {
 317                 ret = -ENOSPC;
 318                 goto err_dma_submit;
 319         }
 320
 321         return 0;
 322
 323  err_dma_submit:
 324         out_be32(&lpbfifo.regs->enable,
 325                                 MPC512X_SCLPC_RESET | MPC512X_SCLPC_FIFO_RESET);
 326  err_dma_prep:
 327         dma_unmap_single(dma_dev->dev, sg_dma_address(&sg),
 328                                                 lpbfifo.req->size, dir);
 329         return ret;
 330 }
 331
 332 static int mpc512x_lpbfifo_submit_locked(struct mpc512x_lpbfifo_request *req)
 333 {
 334         int ret = 0;
 335
 336         if (!lpbfifo.regs)
 337                 return -ENODEV;
 338
 339         /* Check whether a transfer is in progress */
 340         if (lpbfifo.req)
 341                 return -EBUSY;
 342
 343         lpbfifo.wait_lpbfifo_irq = true;
 344         lpbfifo.wait_lpbfifo_callback = true;
 345         lpbfifo.req = req;
 346
 347         ret = mpc512x_lpbfifo_kick();
 348         if (ret != 0)
 349                 lpbfifo.req = NULL; /* Set the FIFO as idle */
 350
 351         return ret;
 352 }
 353
 354 int mpc512x_lpbfifo_submit(struct mpc512x_lpbfifo_request *req)
 355 {
 356         unsigned long flags;
 357         int ret = 0;
 358
 359         spin_lock_irqsave(&lpbfifo.lock, flags);
 360         ret = mpc512x_lpbfifo_submit_locked(req);
 361         spin_unlock_irqrestore(&lpbfifo.lock, flags);
 362
 363         return ret;
 364 }
 365 EXPORT_SYMBOL(mpc512x_lpbfifo_submit);
 366
 367 /*
 368  * LPBFIFO driver uses "ranges" property of "localbus" device tree node
 369  * for being able to determine the chip select number of a client device
 370  * ordering a DMA transfer.
 371  */
 372 static int get_cs_ranges(struct device *dev)
 373 {
 374         int ret = -ENODEV;
 375         struct device_node *lb_node;
 376         const u32 *addr_cells_p;
 377         const u32 *size_cells_p;
 378         int proplen;
 379         size_t i;
 380
 381         lb_node = of_find_compatible_node(NULL, NULL, "fsl,mpc5121-localbus");
 382         if (!lb_node)
 383                 return ret;
 384
 385         /*
 386          * The node defined as compatible with 'fsl,mpc5121-localbus'
 387          * should have two address cells and one size cell.
 388          * Every item of its ranges property should consist of:
 389          * - the first address cell which is the chipselect number;
 390          * - the second address cell which is the offset in the chipselect,
 391          *    must be zero.
 392          * - CPU address of the beginning of an access window;
 393          * - the only size cell which is the size of an access window.
 394          */
 395         addr_cells_p = of_get_property(lb_node, "#address-cells", NULL);
 396         size_cells_p = of_get_property(lb_node, "#size-cells", NULL);
 397         if (addr_cells_p == NULL || *addr_cells_p != 2 ||
 398                                 size_cells_p == NULL || *size_cells_p != 1) {
 399                 goto end;
 400         }
 401
 402         proplen = of_property_count_u32_elems(lb_node, "ranges");
 403         if (proplen <= 0 || proplen % 4 != 0)
 404                 goto end;
 405
 406         lpbfifo.cs_n = proplen / 4;
 407         lpbfifo.cs_ranges = devm_kcalloc(dev, lpbfifo.cs_n,
 408                                         sizeof(struct cs_range), GFP_KERNEL);
 409         if (!lpbfifo.cs_ranges)
 410                 goto end;
 411
 412         if (of_property_read_u32_array(lb_node, "ranges",
 413                                 (u32 *)lpbfifo.cs_ranges, proplen) != 0) {
 414                 goto end;
 415         }
 416
 417         for (i = 0; i < lpbfifo.cs_n; i++) {
 418                 if (lpbfifo.cs_ranges[i].base != 0)
 419                         goto end;
 420         }
 421
 422         ret = 0;
 423
 424  end:
 425         of_node_put(lb_node);
 426         return ret;
 427 }
 428
 429 static int mpc512x_lpbfifo_probe(struct platform_device *pdev)
 430 {
 431         struct resource r;
 432         int ret = 0;
 433
 434         memset(&lpbfifo, 0, sizeof(struct lpbfifo_data));
 435         spin_lock_init(&lpbfifo.lock);
 436
 437         lpbfifo.chan = dma_request_chan(&pdev->dev, "rx-tx");
 438         if (IS_ERR(lpbfifo.chan))
 439                 return PTR_ERR(lpbfifo.chan);
 440
 441         if (of_address_to_resource(pdev->dev.of_node, 0, &r) != 0) {
 442                 dev_err(&pdev->dev, "bad 'reg' in 'sclpc' device tree node\n");
 443                 ret = -ENODEV;
 444                 goto err0;
 445         }
 446
 447         lpbfifo.regs_phys = r.start;
 448         lpbfifo.regs_size = resource_size(&r);
 449
 450         if (!devm_request_mem_region(&pdev->dev, lpbfifo.regs_phys,
 451                                         lpbfifo.regs_size, DRV_NAME)) {
 452                 dev_err(&pdev->dev, "unable to request region\n");
 453                 ret = -EBUSY;
 454                 goto err0;
 455         }
 456
 457         lpbfifo.regs = devm_ioremap(&pdev->dev,
 458                                         lpbfifo.regs_phys, lpbfifo.regs_size);
 459         if (!lpbfifo.regs) {
 460                 dev_err(&pdev->dev, "mapping registers failed\n");
 461                 ret = -ENOMEM;
 462                 goto err0;
 463         }
 464
 465         out_be32(&lpbfifo.regs->enable,
 466                                 MPC512X_SCLPC_RESET | MPC512X_SCLPC_FIFO_RESET);
 467
 468         if (get_cs_ranges(&pdev->dev) != 0) {
 469                 dev_err(&pdev->dev, "bad '/localbus' device tree node\n");
 470                 ret = -ENODEV;
 471                 goto err0;
 472         }
 473
 474         lpbfifo.irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
 475         if (!lpbfifo.irq) {
 476                 dev_err(&pdev->dev, "mapping irq failed\n");
 477                 ret = -ENODEV;
 478                 goto err0;
 479         }
 480
 481         if (request_irq(lpbfifo.irq, mpc512x_lpbfifo_irq, 0,
 482                                                 DRV_NAME, &pdev->dev) != 0) {
 483                 dev_err(&pdev->dev, "requesting irq failed\n");
 484                 ret = -ENODEV;
 485                 goto err1;
 486         }
 487
 488         dev_info(&pdev->dev, "probe succeeded\n");
 489         return 0;
 490
 491  err1:
 492         irq_dispose_mapping(lpbfifo.irq);
 493  err0:
 494         dma_release_channel(lpbfifo.chan);
 495         return ret;
 496 }
 497
 498 static int mpc512x_lpbfifo_remove(struct platform_device *pdev)
 499 {
 500         unsigned long flags;
 501         struct dma_device *dma_dev = lpbfifo.chan->device;
 502         struct mpc512x_lpbfifo __iomem *regs = NULL;
 503
 504         spin_lock_irqsave(&lpbfifo.lock, flags);
 505         regs = lpbfifo.regs;
 506         lpbfifo.regs = NULL;
 507         spin_unlock_irqrestore(&lpbfifo.lock, flags);
 508
 509         dma_dev->device_terminate_all(lpbfifo.chan);
 510         out_be32(&regs->enable, MPC512X_SCLPC_RESET | MPC512X_SCLPC_FIFO_RESET);
 511
 512         free_irq(lpbfifo.irq, &pdev->dev);
 513         irq_dispose_mapping(lpbfifo.irq);
 514         dma_release_channel(lpbfifo.chan);
 515
 516         return 0;
 517 }
 518
 519 static const struct of_device_id mpc512x_lpbfifo_match[] = {
 520         { .compatible = "fsl,mpc512x-lpbfifo", },
 521         {},
 522 };
 523 MODULE_DEVICE_TABLE(of, mpc512x_lpbfifo_match);
 524
 525 static struct platform_driver mpc512x_lpbfifo_driver = {
 526         .probe = mpc512x_lpbfifo_probe,
 527         .remove = mpc512x_lpbfifo_remove,
 528         .driver = {
 529                 .name = DRV_NAME,
 530                 .of_match_table = mpc512x_lpbfifo_match,
 531         },
 532 };
 533
 534 module_platform_driver(mpc512x_lpbfifo_driver);
 535
 536 MODULE_AUTHOR("Alexander Popov <alex.popov@linux.com>");
 537 MODULE_DESCRIPTION("MPC512x LocalPlus Bus FIFO device driver");
 538 MODULE_LICENSE("GPL v2");