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  */
mpc512x_lpbfifo_irq(int irq,void * param)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  */
mpc512x_lpbfifo_callback(void * param)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 
mpc512x_lpbfifo_kick(void)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 
mpc512x_lpbfifo_submit_locked(struct mpc512x_lpbfifo_request * req)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 
mpc512x_lpbfifo_submit(struct mpc512x_lpbfifo_request * req)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  */
get_cs_ranges(struct device * dev)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 
mpc512x_lpbfifo_probe(struct platform_device * pdev)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 
mpc512x_lpbfifo_remove(struct platform_device * pdev)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");
539