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) { 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(®s->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 .of_match_table = mpc512x_lpbfifo_match, 532 }, 533 }; 534 535 module_platform_driver(mpc512x_lpbfifo_driver); 536 537 MODULE_AUTHOR("Alexander Popov <alex.popov@linux.com>"); 538 MODULE_DESCRIPTION("MPC512x LocalPlus Bus FIFO device driver"); 539 MODULE_LICENSE("GPL v2"); 540