aboutsummaryrefslogtreecommitdiff
path: root/drivers/spi/spi-pxa2xx-dma.c
blob: 3c0b55125f1eb6b85989a549fc50c51f114b9b0d (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
/*
 * PXA2xx SPI DMA engine support.
 *
 * Copyright (C) 2013, Intel Corporation
 * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/init.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/pxa2xx_ssp.h>
#include <linux/scatterlist.h>
#include <linux/sizes.h>
#include <linux/spi/spi.h>
#include <linux/spi/pxa2xx_spi.h>

#include "spi-pxa2xx.h"

static int pxa2xx_spi_map_dma_buffer(struct driver_data *drv_data,
				     enum dma_data_direction dir)
{
	int i, nents, len = drv_data->len;
	struct scatterlist *sg;
	struct device *dmadev;
	struct sg_table *sgt;
	void *buf, *pbuf;

	/*
	 * Some DMA controllers have problems transferring buffers that are
	 * not multiple of 4 bytes. So we truncate the transfer so that it
	 * is suitable for such controllers, and handle the trailing bytes
	 * manually after the DMA completes.
	 *
	 * REVISIT: It would be better if this information could be
	 * retrieved directly from the DMA device in a similar way than
	 * ->copy_align etc. is done.
	 */
	len = ALIGN(drv_data->len, 4);

	if (dir == DMA_TO_DEVICE) {
		dmadev = drv_data->tx_chan->device->dev;
		sgt = &drv_data->tx_sgt;
		buf = drv_data->tx;
		drv_data->tx_map_len = len;
	} else {
		dmadev = drv_data->rx_chan->device->dev;
		sgt = &drv_data->rx_sgt;
		buf = drv_data->rx;
		drv_data->rx_map_len = len;
	}

	nents = DIV_ROUND_UP(len, SZ_2K);
	if (nents != sgt->nents) {
		int ret;

		sg_free_table(sgt);
		ret = sg_alloc_table(sgt, nents, GFP_ATOMIC);
		if (ret)
			return ret;
	}

	pbuf = buf;
	for_each_sg(sgt->sgl, sg, sgt->nents, i) {
		size_t bytes = min_t(size_t, len, SZ_2K);

		if (buf)
			sg_set_buf(sg, pbuf, bytes);
		else
			sg_set_buf(sg, drv_data->dummy, bytes);

		pbuf += bytes;
		len -= bytes;
	}

	nents = dma_map_sg(dmadev, sgt->sgl, sgt->nents, dir);
	if (!nents)
		return -ENOMEM;

	return nents;
}

static void pxa2xx_spi_unmap_dma_buffer(struct driver_data *drv_data,
					enum dma_data_direction dir)
{
	struct device *dmadev;
	struct sg_table *sgt;

	if (dir == DMA_TO_DEVICE) {
		dmadev = drv_data->tx_chan->device->dev;
		sgt = &drv_data->tx_sgt;
	} else {
		dmadev = drv_data->rx_chan->device->dev;
		sgt = &drv_data->rx_sgt;
	}

	dma_unmap_sg(dmadev, sgt->sgl, sgt->nents, dir);
}

static void pxa2xx_spi_unmap_dma_buffers(struct driver_data *drv_data)
{
	if (!drv_data->dma_mapped)
		return;

	pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_FROM_DEVICE);
	pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_TO_DEVICE);

	drv_data->dma_mapped = 0;
}

static void pxa2xx_spi_dma_transfer_complete(struct driver_data *drv_data,
					     bool error)
{
	struct spi_message *msg = drv_data->cur_msg;

	/*
	 * It is possible that one CPU is handling ROR interrupt and other
	 * just gets DMA completion. Calling pump_transfers() twice for the
	 * same transfer leads to problems thus we prevent concurrent calls
	 * by using ->dma_running.
	 */
	if (atomic_dec_and_test(&drv_data->dma_running)) {
		void __iomem *reg = drv_data->ioaddr;

		/*
		 * If the other CPU is still handling the ROR interrupt we
		 * might not know about the error yet. So we re-check the
		 * ROR bit here before we clear the status register.
		 */
		if (!error) {
			u32 status = read_SSSR(reg) & drv_data->mask_sr;
			error = status & SSSR_ROR;
		}

		/* Clear status & disable interrupts */
		write_SSCR1(read_SSCR1(reg) & ~drv_data->dma_cr1, reg);
		write_SSSR_CS(drv_data, drv_data->clear_sr);
		if (!pxa25x_ssp_comp(drv_data))
			write_SSTO(0, reg);

		if (!error) {
			pxa2xx_spi_unmap_dma_buffers(drv_data);

			/* Handle the last bytes of unaligned transfer */
			drv_data->tx += drv_data->tx_map_len;
			drv_data->write(drv_data);

			drv_data->rx += drv_data->rx_map_len;
			drv_data->read(drv_data);

			msg->actual_length += drv_data->len;
			msg->state = pxa2xx_spi_next_transfer(drv_data);
		} else {
			/* In case we got an error we disable the SSP now */
			write_SSCR0(read_SSCR0(reg) & ~SSCR0_SSE, reg);

			msg->state = ERROR_STATE;
		}

		tasklet_schedule(&drv_data->pump_transfers);
	}
}

static void pxa2xx_spi_dma_callback(void *data)
{
	pxa2xx_spi_dma_transfer_complete(data, false);
}

static struct dma_async_tx_descriptor *
pxa2xx_spi_dma_prepare_one(struct driver_data *drv_data,
			   enum dma_transfer_direction dir)
{
	struct pxa2xx_spi_master *pdata = drv_data->master_info;
	struct chip_data *chip = drv_data->cur_chip;
	enum dma_slave_buswidth width;
	struct dma_slave_config cfg;
	struct dma_chan *chan;
	struct sg_table *sgt;
	int nents, ret;

	switch (drv_data->n_bytes) {
	case 1:
		width = DMA_SLAVE_BUSWIDTH_1_BYTE;
		break;
	case 2:
		width = DMA_SLAVE_BUSWIDTH_2_BYTES;
		break;
	default:
		width = DMA_SLAVE_BUSWIDTH_4_BYTES;
		break;
	}

	memset(&cfg, 0, sizeof(cfg));
	cfg.direction = dir;

	if (dir == DMA_MEM_TO_DEV) {
		cfg.dst_addr = drv_data->ssdr_physical;
		cfg.dst_addr_width = width;
		cfg.dst_maxburst = chip->dma_burst_size;
		cfg.slave_id = pdata->tx_slave_id;

		sgt = &drv_data->tx_sgt;
		nents = drv_data->tx_nents;
		chan = drv_data->tx_chan;
	} else {
		cfg.src_addr = drv_data->ssdr_physical;
		cfg.src_addr_width = width;
		cfg.src_maxburst = chip->dma_burst_size;
		cfg.slave_id = pdata->rx_slave_id;

		sgt = &drv_data->rx_sgt;
		nents = drv_data->rx_nents;
		chan = drv_data->rx_chan;
	}

	ret = dmaengine_slave_config(chan, &cfg);
	if (ret) {
		dev_warn(&drv_data->pdev->dev, "DMA slave config failed\n");
		return NULL;
	}

	return dmaengine_prep_slave_sg(chan, sgt->sgl, nents, dir,
				       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
}

static bool pxa2xx_spi_dma_filter(struct dma_chan *chan, void *param)
{
	const struct pxa2xx_spi_master *pdata = param;

	return chan->chan_id == pdata->tx_chan_id ||
	       chan->chan_id == pdata->rx_chan_id;
}

bool pxa2xx_spi_dma_is_possible(size_t len)
{
	return len <= MAX_DMA_LEN;
}

int pxa2xx_spi_map_dma_buffers(struct driver_data *drv_data)
{
	const struct chip_data *chip = drv_data->cur_chip;
	int ret;

	if (!chip->enable_dma)
		return 0;

	/* Don't bother with DMA if we can't do even a single burst */
	if (drv_data->len < chip->dma_burst_size)
		return 0;

	ret = pxa2xx_spi_map_dma_buffer(drv_data, DMA_TO_DEVICE);
	if (ret <= 0) {
		dev_warn(&drv_data->pdev->dev, "failed to DMA map TX\n");
		return 0;
	}

	drv_data->tx_nents = ret;

	ret = pxa2xx_spi_map_dma_buffer(drv_data, DMA_FROM_DEVICE);
	if (ret <= 0) {
		pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_TO_DEVICE);
		dev_warn(&drv_data->pdev->dev, "failed to DMA map RX\n");
		return 0;
	}

	drv_data->rx_nents = ret;
	return 1;
}

irqreturn_t pxa2xx_spi_dma_transfer(struct driver_data *drv_data)
{
	u32 status;

	status = read_SSSR(drv_data->ioaddr) & drv_data->mask_sr;
	if (status & SSSR_ROR) {
		dev_err(&drv_data->pdev->dev, "FIFO overrun\n");

		dmaengine_terminate_all(drv_data->rx_chan);
		dmaengine_terminate_all(drv_data->tx_chan);

		pxa2xx_spi_dma_transfer_complete(drv_data, true);
		return IRQ_HANDLED;
	}

	return IRQ_NONE;
}

int pxa2xx_spi_dma_prepare(struct driver_data *drv_data, u32 dma_burst)
{
	struct dma_async_tx_descriptor *tx_desc, *rx_desc;

	tx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_MEM_TO_DEV);
	if (!tx_desc) {
		dev_err(&drv_data->pdev->dev,
			"failed to get DMA TX descriptor\n");
		return -EBUSY;
	}

	rx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_DEV_TO_MEM);
	if (!rx_desc) {
		dev_err(&drv_data->pdev->dev,
			"failed to get DMA RX descriptor\n");
		return -EBUSY;
	}

	/* We are ready when RX completes */
	rx_desc->callback = pxa2xx_spi_dma_callback;
	rx_desc->callback_param = drv_data;

	dmaengine_submit(rx_desc);
	dmaengine_submit(tx_desc);
	return 0;
}

void pxa2xx_spi_dma_start(struct driver_data *drv_data)
{
	dma_async_issue_pending(drv_data->rx_chan);
	dma_async_issue_pending(drv_data->tx_chan);

	atomic_set(&drv_data->dma_running, 1);
}

int pxa2xx_spi_dma_setup(struct driver_data *drv_data)
{
	struct pxa2xx_spi_master *pdata = drv_data->master_info;
	struct device *dev = &drv_data->pdev->dev;
	dma_cap_mask_t mask;

	dma_cap_zero(mask);
	dma_cap_set(DMA_SLAVE, mask);

	drv_data->dummy = devm_kzalloc(dev, SZ_2K, GFP_KERNEL);
	if (!drv_data->dummy)
		return -ENOMEM;

	drv_data->tx_chan = dma_request_slave_channel_compat(mask,
				pxa2xx_spi_dma_filter, pdata, dev, "tx");
	if (!drv_data->tx_chan)
		return -ENODEV;

	drv_data->rx_chan = dma_request_slave_channel_compat(mask,
				pxa2xx_spi_dma_filter, pdata, dev, "rx");
	if (!drv_data->rx_chan) {
		dma_release_channel(drv_data->tx_chan);
		drv_data->tx_chan = NULL;
		return -ENODEV;
	}

	return 0;
}

void pxa2xx_spi_dma_release(struct driver_data *drv_data)
{
	if (drv_data->rx_chan) {
		dmaengine_terminate_all(drv_data->rx_chan);
		dma_release_channel(drv_data->rx_chan);
		sg_free_table(&drv_data->rx_sgt);
		drv_data->rx_chan = NULL;
	}
	if (drv_data->tx_chan) {
		dmaengine_terminate_all(drv_data->tx_chan);
		dma_release_channel(drv_data->tx_chan);
		sg_free_table(&drv_data->tx_sgt);
		drv_data->tx_chan = NULL;
	}
}

void pxa2xx_spi_dma_resume(struct driver_data *drv_data)
{
}

int pxa2xx_spi_set_dma_burst_and_threshold(struct chip_data *chip,
					   struct spi_device *spi,
					   u8 bits_per_word, u32 *burst_code,
					   u32 *threshold)
{
	struct pxa2xx_spi_chip *chip_info = spi->controller_data;

	/*
	 * If the DMA burst size is given in chip_info we use that,
	 * otherwise we use the default. Also we use the default FIFO
	 * thresholds for now.
	 */
	*burst_code = chip_info ? chip_info->dma_burst_size : 16;
	*threshold = SSCR1_RxTresh(RX_THRESH_DFLT)
		   | SSCR1_TxTresh(TX_THRESH_DFLT);

	return 0;
}