aboutsummaryrefslogtreecommitdiff
path: root/arch/powerpc/platforms/52xx/mpc52xx_lpbfifo.c
blob: 9940ce8a2d4eff3fffb9d5458a46e98683a58351 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
/*
 * LocalPlus Bus FIFO driver for the Freescale MPC52xx.
 *
 * Copyright (C) 2009 Secret Lab Technologies Ltd.
 *
 * This file is released under the GPLv2
 *
 * Todo:
 * - Add support for multiple requests to be queued.
 */

#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/spinlock.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/mpc52xx.h>
#include <asm/time.h>

#include <sysdev/bestcomm/bestcomm.h>
#include <sysdev/bestcomm/bestcomm_priv.h>
#include <sysdev/bestcomm/gen_bd.h>

MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
MODULE_DESCRIPTION("MPC5200 LocalPlus FIFO device driver");
MODULE_LICENSE("GPL");

#define LPBFIFO_REG_PACKET_SIZE		(0x00)
#define LPBFIFO_REG_START_ADDRESS	(0x04)
#define LPBFIFO_REG_CONTROL		(0x08)
#define LPBFIFO_REG_ENABLE		(0x0C)
#define LPBFIFO_REG_BYTES_DONE_STATUS	(0x14)
#define LPBFIFO_REG_FIFO_DATA		(0x40)
#define LPBFIFO_REG_FIFO_STATUS		(0x44)
#define LPBFIFO_REG_FIFO_CONTROL	(0x48)
#define LPBFIFO_REG_FIFO_ALARM		(0x4C)

struct mpc52xx_lpbfifo {
	struct device *dev;
	phys_addr_t regs_phys;
	void __iomem *regs;
	int irq;
	spinlock_t lock;

	struct bcom_task *bcom_tx_task;
	struct bcom_task *bcom_rx_task;
	struct bcom_task *bcom_cur_task;

	/* Current state data */
	struct mpc52xx_lpbfifo_request *req;
	int dma_irqs_enabled;
};

/* The MPC5200 has only one fifo, so only need one instance structure */
static struct mpc52xx_lpbfifo lpbfifo;

/**
 * mpc52xx_lpbfifo_kick - Trigger the next block of data to be transferred
 */
static void mpc52xx_lpbfifo_kick(struct mpc52xx_lpbfifo_request *req)
{
	size_t transfer_size = req->size - req->pos;
	struct bcom_bd *bd;
	void __iomem *reg;
	u32 *data;
	int i;
	int bit_fields;
	int dma = !(req->flags & MPC52XX_LPBFIFO_FLAG_NO_DMA);
	int write = req->flags & MPC52XX_LPBFIFO_FLAG_WRITE;
	int poll_dma = req->flags & MPC52XX_LPBFIFO_FLAG_POLL_DMA;

	/* Set and clear the reset bits; is good practice in User Manual */
	out_be32(lpbfifo.regs + LPBFIFO_REG_ENABLE, 0x01010000);

	/* set master enable bit */
	out_be32(lpbfifo.regs + LPBFIFO_REG_ENABLE, 0x00000001);
	if (!dma) {
		/* While the FIFO can be setup for transfer sizes as large as
		 * 16M-1, the FIFO itself is only 512 bytes deep and it does
		 * not generate interrupts for FIFO full events (only transfer
		 * complete will raise an IRQ).  Therefore when not using
		 * Bestcomm to drive the FIFO it needs to either be polled, or
		 * transfers need to constrained to the size of the fifo.
		 *
		 * This driver restricts the size of the transfer
		 */
		if (transfer_size > 512)
			transfer_size = 512;

		/* Load the FIFO with data */
		if (write) {
			reg = lpbfifo.regs + LPBFIFO_REG_FIFO_DATA;
			data = req->data + req->pos;
			for (i = 0; i < transfer_size; i += 4)
				out_be32(reg, *data++);
		}

		/* Unmask both error and completion irqs */
		out_be32(lpbfifo.regs + LPBFIFO_REG_ENABLE, 0x00000301);
	} else {
		/* Choose the correct direction
		 *
		 * Configure the watermarks so DMA will always complete correctly.
		 * It may be worth experimenting with the ALARM value to see if
		 * there is a performance impacit.  However, if it is wrong there
		 * is a risk of DMA not transferring the last chunk of data
		 */
		if (write) {
			out_be32(lpbfifo.regs + LPBFIFO_REG_FIFO_ALARM, 0x1e4);
			out_8(lpbfifo.regs + LPBFIFO_REG_FIFO_CONTROL, 7);
			lpbfifo.bcom_cur_task = lpbfifo.bcom_tx_task;
		} else {
			out_be32(lpbfifo.regs + LPBFIFO_REG_FIFO_ALARM, 0x1ff);
			out_8(lpbfifo.regs + LPBFIFO_REG_FIFO_CONTROL, 0);
			lpbfifo.bcom_cur_task = lpbfifo.bcom_rx_task;

			if (poll_dma) {
				if (lpbfifo.dma_irqs_enabled) {
					disable_irq(bcom_get_task_irq(lpbfifo.bcom_rx_task));
					lpbfifo.dma_irqs_enabled = 0;
				}
			} else {
				if (!lpbfifo.dma_irqs_enabled) {
					enable_irq(bcom_get_task_irq(lpbfifo.bcom_rx_task));
					lpbfifo.dma_irqs_enabled = 1;
				}
			}
		}

		bd = bcom_prepare_next_buffer(lpbfifo.bcom_cur_task);
		bd->status = transfer_size;
		if (!write) {
			/*
			 * In the DMA read case, the DMA doesn't complete,
			 * possibly due to incorrect watermarks in the ALARM
			 * and CONTROL regs. For now instead of trying to
			 * determine the right watermarks that will make this
			 * work, just increase the number of bytes the FIFO is
			 * expecting.
			 *
			 * When submitting another operation, the FIFO will get
			 * reset, so the condition of the FIFO waiting for a
			 * non-existent 4 bytes will get cleared.
			 */
			transfer_size += 4; /* BLECH! */
		}
		bd->data[0] = req->data_phys + req->pos;
		bcom_submit_next_buffer(lpbfifo.bcom_cur_task, NULL);

		/* error irq & master enabled bit */
		bit_fields = 0x00000201;

		/* Unmask irqs */
		if (write && (!poll_dma))
			bit_fields |= 0x00000100; /* completion irq too */
		out_be32(lpbfifo.regs + LPBFIFO_REG_ENABLE, bit_fields);
	}

	/* Set transfer size, width, chip select and READ mode */
	out_be32(lpbfifo.regs + LPBFIFO_REG_START_ADDRESS,
		 req->offset + req->pos);
	out_be32(lpbfifo.regs + LPBFIFO_REG_PACKET_SIZE, transfer_size);

	bit_fields = req->cs << 24 | 0x000008;
	if (!write)
		bit_fields |= 0x010000; /* read mode */
	out_be32(lpbfifo.regs + LPBFIFO_REG_CONTROL, bit_fields);

	/* Kick it off */
	out_8(lpbfifo.regs + LPBFIFO_REG_PACKET_SIZE, 0x01);
	if (dma)
		bcom_enable(lpbfifo.bcom_cur_task);
}

/**
 * mpc52xx_lpbfifo_irq - IRQ handler for LPB FIFO
 *
 * On transmit, the dma completion irq triggers before the fifo completion
 * triggers.  Handle the dma completion here instead of the LPB FIFO Bestcomm
 * task completion irq because everything is not really done until the LPB FIFO
 * completion irq triggers.
 *
 * In other words:
 * For DMA, on receive, the "Fat Lady" is the bestcom completion irq. on
 * transmit, the fifo completion irq is the "Fat Lady". The opera (or in this
 * case the DMA/FIFO operation) is not finished until the "Fat Lady" sings.
 *
 * Reasons for entering this routine:
 * 1) PIO mode rx and tx completion irq
 * 2) DMA interrupt mode tx completion irq
 * 3) DMA polled mode tx
 *
 * Exit conditions:
 * 1) Transfer aborted
 * 2) FIFO complete without DMA; more data to do
 * 3) FIFO complete without DMA; all data transferred
 * 4) FIFO complete using DMA
 *
 * Condition 1 can occur regardless of whether or not DMA is used.
 * It requires executing the callback to report the error and exiting
 * immediately.
 *
 * Condition 2 requires programming the FIFO with the next block of data
 *
 * Condition 3 requires executing the callback to report completion
 *
 * Condition 4 means the same as 3, except that we also retrieve the bcom
 * buffer so DMA doesn't get clogged up.
 *
 * To make things trickier, the spinlock must be dropped before
 * executing the callback, otherwise we could end up with a deadlock
 * or nested spinlock condition.  The out path is non-trivial, so
 * extra fiddling is done to make sure all paths lead to the same
 * outbound code.
 */
static irqreturn_t mpc52xx_lpbfifo_irq(int irq, void *dev_id)
{
	struct mpc52xx_lpbfifo_request *req;
	u32 status = in_8(lpbfifo.regs + LPBFIFO_REG_BYTES_DONE_STATUS);
	void __iomem *reg;
	u32 *data;
	int count, i;
	int do_callback = 0;
	u32 ts;
	unsigned long flags;
	int dma, write, poll_dma;

	spin_lock_irqsave(&lpbfifo.lock, flags);
	ts = get_tbl();

	req = lpbfifo.req;
	if (!req) {
		spin_unlock_irqrestore(&lpbfifo.lock, flags);
		pr_err("bogus LPBFIFO IRQ\n");
		return IRQ_HANDLED;
	}

	dma = !(req->flags & MPC52XX_LPBFIFO_FLAG_NO_DMA);
	write = req->flags & MPC52XX_LPBFIFO_FLAG_WRITE;
	poll_dma = req->flags & MPC52XX_LPBFIFO_FLAG_POLL_DMA;

	if (dma && !write) {
		spin_unlock_irqrestore(&lpbfifo.lock, flags);
		pr_err("bogus LPBFIFO IRQ (dma and not writting)\n");
		return IRQ_HANDLED;
	}

	if ((status & 0x01) == 0) {
		goto out;
	}

	/* check abort bit */
	if (status & 0x10) {
		out_be32(lpbfifo.regs + LPBFIFO_REG_ENABLE, 0x01010000);
		do_callback = 1;
		goto out;
	}

	/* Read result from hardware */
	count = in_be32(lpbfifo.regs + LPBFIFO_REG_BYTES_DONE_STATUS);
	count &= 0x00ffffff;

	if (!dma && !write) {
		/* copy the data out of the FIFO */
		reg = lpbfifo.regs + LPBFIFO_REG_FIFO_DATA;
		data = req->data + req->pos;
		for (i = 0; i < count; i += 4)
			*data++ = in_be32(reg);
	}

	/* Update transfer position and count */
	req->pos += count;

	/* Decide what to do next */
	if (req->size - req->pos)
		mpc52xx_lpbfifo_kick(req); /* more work to do */
	else
		do_callback = 1;

 out:
	/* Clear the IRQ */
	out_8(lpbfifo.regs + LPBFIFO_REG_BYTES_DONE_STATUS, 0x01);

	if (dma && (status & 0x11)) {
		/*
		 * Count the DMA as complete only when the FIFO completion
		 * status or abort bits are set.
		 *
		 * (status & 0x01) should always be the case except sometimes
		 * when using polled DMA.
		 *
		 * (status & 0x10) {transfer aborted}: This case needs more
		 * testing.
		 */
		bcom_retrieve_buffer(lpbfifo.bcom_cur_task, &status, NULL);
	}
	req->last_byte = ((u8 *)req->data)[req->size - 1];

	/* When the do_callback flag is set; it means the transfer is finished
	 * so set the FIFO as idle */
	if (do_callback)
		lpbfifo.req = NULL;

	if (irq != 0) /* don't increment on polled case */
		req->irq_count++;

	req->irq_ticks += get_tbl() - ts;
	spin_unlock_irqrestore(&lpbfifo.lock, flags);

	/* Spinlock is released; it is now safe to call the callback */
	if (do_callback && req->callback)
		req->callback(req);

	return IRQ_HANDLED;
}

/**
 * mpc52xx_lpbfifo_bcom_irq - IRQ handler for LPB FIFO Bestcomm task
 *
 * Only used when receiving data.
 */
static irqreturn_t mpc52xx_lpbfifo_bcom_irq(int irq, void *dev_id)
{
	struct mpc52xx_lpbfifo_request *req;
	unsigned long flags;
	u32 status;
	u32 ts;

	spin_lock_irqsave(&lpbfifo.lock, flags);
	ts = get_tbl();

	req = lpbfifo.req;
	if (!req || (req->flags & MPC52XX_LPBFIFO_FLAG_NO_DMA)) {
		spin_unlock_irqrestore(&lpbfifo.lock, flags);
		return IRQ_HANDLED;
	}

	if (irq != 0) /* don't increment on polled case */
		req->irq_count++;

	if (!bcom_buffer_done(lpbfifo.bcom_cur_task)) {
		spin_unlock_irqrestore(&lpbfifo.lock, flags);

		req->buffer_not_done_cnt++;
		if ((req->buffer_not_done_cnt % 1000) == 0)
			pr_err("transfer stalled\n");

		return IRQ_HANDLED;
	}

	bcom_retrieve_buffer(lpbfifo.bcom_cur_task, &status, NULL);

	req->last_byte = ((u8 *)req->data)[req->size - 1];

	req->pos = status & 0x00ffffff;

	/* Mark the FIFO as idle */
	lpbfifo.req = NULL;

	/* Release the lock before calling out to the callback. */
	req->irq_ticks += get_tbl() - ts;
	spin_unlock_irqrestore(&lpbfifo.lock, flags);

	if (req->callback)
		req->callback(req);

	return IRQ_HANDLED;
}

/**
 * mpc52xx_lpbfifo_bcom_poll - Poll for DMA completion
 */
void mpc52xx_lpbfifo_poll(void)
{
	struct mpc52xx_lpbfifo_request *req = lpbfifo.req;
	int dma = !(req->flags & MPC52XX_LPBFIFO_FLAG_NO_DMA);
	int write = req->flags & MPC52XX_LPBFIFO_FLAG_WRITE;

	/*
	 * For more information, see comments on the "Fat Lady" 
	 */
	if (dma && write)
		mpc52xx_lpbfifo_irq(0, NULL);
	else 
		mpc52xx_lpbfifo_bcom_irq(0, NULL);
}
EXPORT_SYMBOL(mpc52xx_lpbfifo_poll);

/**
 * mpc52xx_lpbfifo_submit - Submit an LPB FIFO transfer request.
 * @req: Pointer to request structure
 */
int mpc52xx_lpbfifo_submit(struct mpc52xx_lpbfifo_request *req)
{
	unsigned long flags;

	if (!lpbfifo.regs)
		return -ENODEV;

	spin_lock_irqsave(&lpbfifo.lock, flags);

	/* If the req pointer is already set, then a transfer is in progress */
	if (lpbfifo.req) {
		spin_unlock_irqrestore(&lpbfifo.lock, flags);
		return -EBUSY;
	}

	/* Setup the transfer */
	lpbfifo.req = req;
	req->irq_count = 0;
	req->irq_ticks = 0;
	req->buffer_not_done_cnt = 0;
	req->pos = 0;

	mpc52xx_lpbfifo_kick(req);
	spin_unlock_irqrestore(&lpbfifo.lock, flags);
	return 0;
}
EXPORT_SYMBOL(mpc52xx_lpbfifo_submit);

void mpc52xx_lpbfifo_abort(struct mpc52xx_lpbfifo_request *req)
{
	unsigned long flags;

	spin_lock_irqsave(&lpbfifo.lock, flags);
	if (lpbfifo.req == req) {
		/* Put it into reset and clear the state */
		bcom_gen_bd_rx_reset(lpbfifo.bcom_rx_task);
		bcom_gen_bd_tx_reset(lpbfifo.bcom_tx_task);
		out_be32(lpbfifo.regs + LPBFIFO_REG_ENABLE, 0x01010000);
		lpbfifo.req = NULL;
	}
	spin_unlock_irqrestore(&lpbfifo.lock, flags);
}
EXPORT_SYMBOL(mpc52xx_lpbfifo_abort);

static int __devinit mpc52xx_lpbfifo_probe(struct platform_device *op)
{
	struct resource res;
	int rc = -ENOMEM;

	if (lpbfifo.dev != NULL)
		return -ENOSPC;

	lpbfifo.irq = irq_of_parse_and_map(op->dev.of_node, 0);
	if (!lpbfifo.irq)
		return -ENODEV;

	if (of_address_to_resource(op->dev.of_node, 0, &res))
		return -ENODEV;
	lpbfifo.regs_phys = res.start;
	lpbfifo.regs = of_iomap(op->dev.of_node, 0);
	if (!lpbfifo.regs)
		return -ENOMEM;

	spin_lock_init(&lpbfifo.lock);

	/* Put FIFO into reset */
	out_be32(lpbfifo.regs + LPBFIFO_REG_ENABLE, 0x01010000);

	/* Register the interrupt handler */
	rc = request_irq(lpbfifo.irq, mpc52xx_lpbfifo_irq, 0,
			 "mpc52xx-lpbfifo", &lpbfifo);
	if (rc)
		goto err_irq;

	/* Request the Bestcomm receive (fifo --> memory) task and IRQ */
	lpbfifo.bcom_rx_task =
		bcom_gen_bd_rx_init(2, res.start + LPBFIFO_REG_FIFO_DATA,
				    BCOM_INITIATOR_SCLPC, BCOM_IPR_SCLPC,
				    16*1024*1024);
	if (!lpbfifo.bcom_rx_task)
		goto err_bcom_rx;

	rc = request_irq(bcom_get_task_irq(lpbfifo.bcom_rx_task),
			 mpc52xx_lpbfifo_bcom_irq, 0,
			 "mpc52xx-lpbfifo-rx", &lpbfifo);
	if (rc)
		goto err_bcom_rx_irq;

	lpbfifo.dma_irqs_enabled = 1;

	/* Request the Bestcomm transmit (memory --> fifo) task and IRQ */
	lpbfifo.bcom_tx_task =
		bcom_gen_bd_tx_init(2, res.start + LPBFIFO_REG_FIFO_DATA,
				    BCOM_INITIATOR_SCLPC, BCOM_IPR_SCLPC);
	if (!lpbfifo.bcom_tx_task)
		goto err_bcom_tx;

	lpbfifo.dev = &op->dev;
	return 0;

 err_bcom_tx:
	free_irq(bcom_get_task_irq(lpbfifo.bcom_rx_task), &lpbfifo);
 err_bcom_rx_irq:
	bcom_gen_bd_rx_release(lpbfifo.bcom_rx_task);
 err_bcom_rx:
 err_irq:
	iounmap(lpbfifo.regs);
	lpbfifo.regs = NULL;

	dev_err(&op->dev, "mpc52xx_lpbfifo_probe() failed\n");
	return -ENODEV;
}


static int __devexit mpc52xx_lpbfifo_remove(struct platform_device *op)
{
	if (lpbfifo.dev != &op->dev)
		return 0;

	/* Put FIFO in reset */
	out_be32(lpbfifo.regs + LPBFIFO_REG_ENABLE, 0x01010000);

	/* Release the bestcomm transmit task */
	free_irq(bcom_get_task_irq(lpbfifo.bcom_tx_task), &lpbfifo);
	bcom_gen_bd_tx_release(lpbfifo.bcom_tx_task);
	
	/* Release the bestcomm receive task */
	free_irq(bcom_get_task_irq(lpbfifo.bcom_rx_task), &lpbfifo);
	bcom_gen_bd_rx_release(lpbfifo.bcom_rx_task);

	free_irq(lpbfifo.irq, &lpbfifo);
	iounmap(lpbfifo.regs);
	lpbfifo.regs = NULL;
	lpbfifo.dev = NULL;

	return 0;
}

static struct of_device_id mpc52xx_lpbfifo_match[] __devinitconst = {
	{ .compatible = "fsl,mpc5200-lpbfifo", },
	{},
};

static struct platform_driver mpc52xx_lpbfifo_driver = {
	.driver = {
		.name = "mpc52xx-lpbfifo",
		.owner = THIS_MODULE,
		.of_match_table = mpc52xx_lpbfifo_match,
	},
	.probe = mpc52xx_lpbfifo_probe,
	.remove = __devexit_p(mpc52xx_lpbfifo_remove),
};

/***********************************************************************
 * Module init/exit
 */
static int __init mpc52xx_lpbfifo_init(void)
{
	return platform_driver_register(&mpc52xx_lpbfifo_driver);
}
module_init(mpc52xx_lpbfifo_init);

static void __exit mpc52xx_lpbfifo_exit(void)
{
	platform_driver_unregister(&mpc52xx_lpbfifo_driver);
}
module_exit(mpc52xx_lpbfifo_exit);