/drivers/mmc/host/tmio_mmc_dma.c

  1/*
  2 * linux/drivers/mmc/tmio_mmc_dma.c
  3 *
  4 * Copyright (C) 2010-2011 Guennadi Liakhovetski
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License version 2 as
  8 * published by the Free Software Foundation.
  9 *
 10 * DMA function for TMIO MMC implementations
 11 */
 12
 13#include <linux/device.h>
 14#include <linux/dmaengine.h>
 15#include <linux/mfd/tmio.h>
 16#include <linux/mmc/host.h>
 17#include <linux/mmc/tmio.h>
 18#include <linux/pagemap.h>
 19#include <linux/scatterlist.h>
 20
 21#include "tmio_mmc.h"
 22
 23#define TMIO_MMC_MIN_DMA_LEN 8
 24
 25static void tmio_mmc_enable_dma(struct tmio_mmc_host *host, bool enable)
 26{
 27#if defined(CONFIG_SUPERH) || defined(CONFIG_ARCH_SHMOBILE)
 28	/* Switch DMA mode on or off - SuperH specific? */
 29	writew(enable ? 2 : 0, host->ctl + (0xd8 << host->bus_shift));
 30#endif
 31}
 32
 33static void tmio_mmc_start_dma_rx(struct tmio_mmc_host *host)
 34{
 35	struct scatterlist *sg = host->sg_ptr, *sg_tmp;
 36	struct dma_async_tx_descriptor *desc = NULL;
 37	struct dma_chan *chan = host->chan_rx;
 38	struct tmio_mmc_data *pdata = host->pdata;
 39	dma_cookie_t cookie;
 40	int ret, i;
 41	bool aligned = true, multiple = true;
 42	unsigned int align = (1 << pdata->dma->alignment_shift) - 1;
 43
 44	for_each_sg(sg, sg_tmp, host->sg_len, i) {
 45		if (sg_tmp->offset & align)
 46			aligned = false;
 47		if (sg_tmp->length & align) {
 48			multiple = false;
 49			break;
 50		}
 51	}
 52
 53	if ((!aligned && (host->sg_len > 1 || sg->length > PAGE_CACHE_SIZE ||
 54			  (align & PAGE_MASK))) || !multiple) {
 55		ret = -EINVAL;
 56		goto pio;
 57	}
 58
 59	if (sg->length < TMIO_MMC_MIN_DMA_LEN) {
 60		host->force_pio = true;
 61		return;
 62	}
 63
 64	tmio_mmc_disable_mmc_irqs(host, TMIO_STAT_RXRDY);
 65
 66	/* The only sg element can be unaligned, use our bounce buffer then */
 67	if (!aligned) {
 68		sg_init_one(&host->bounce_sg, host->bounce_buf, sg->length);
 69		host->sg_ptr = &host->bounce_sg;
 70		sg = host->sg_ptr;
 71	}
 72
 73	ret = dma_map_sg(chan->device->dev, sg, host->sg_len, DMA_FROM_DEVICE);
 74	if (ret > 0)
 75		desc = chan->device->device_prep_slave_sg(chan, sg, ret,
 76			DMA_FROM_DEVICE, DMA_CTRL_ACK);
 77
 78	if (desc) {
 79		cookie = dmaengine_submit(desc);
 80		if (cookie < 0) {
 81			desc = NULL;
 82			ret = cookie;
 83		}
 84	}
 85	dev_dbg(&host->pdev->dev, "%s(): mapped %d -> %d, cookie %d, rq %p\n",
 86		__func__, host->sg_len, ret, cookie, host->mrq);
 87
 88pio:
 89	if (!desc) {
 90		/* DMA failed, fall back to PIO */
 91		if (ret >= 0)
 92			ret = -EIO;
 93		host->chan_rx = NULL;
 94		dma_release_channel(chan);
 95		/* Free the Tx channel too */
 96		chan = host->chan_tx;
 97		if (chan) {
 98			host->chan_tx = NULL;
 99			dma_release_channel(chan);
100		}
101		dev_warn(&host->pdev->dev,
102			 "DMA failed: %d, falling back to PIO\n", ret);
103		tmio_mmc_enable_dma(host, false);
104	}
105
106	dev_dbg(&host->pdev->dev, "%s(): desc %p, cookie %d, sg[%d]\n", __func__,
107		desc, cookie, host->sg_len);
108}
109
110static void tmio_mmc_start_dma_tx(struct tmio_mmc_host *host)
111{
112	struct scatterlist *sg = host->sg_ptr, *sg_tmp;
113	struct dma_async_tx_descriptor *desc = NULL;
114	struct dma_chan *chan = host->chan_tx;
115	struct tmio_mmc_data *pdata = host->pdata;
116	dma_cookie_t cookie;
117	int ret, i;
118	bool aligned = true, multiple = true;
119	unsigned int align = (1 << pdata->dma->alignment_shift) - 1;
120
121	for_each_sg(sg, sg_tmp, host->sg_len, i) {
122		if (sg_tmp->offset & align)
123			aligned = false;
124		if (sg_tmp->length & align) {
125			multiple = false;
126			break;
127		}
128	}
129
130	if ((!aligned && (host->sg_len > 1 || sg->length > PAGE_CACHE_SIZE ||
131			  (align & PAGE_MASK))) || !multiple) {
132		ret = -EINVAL;
133		goto pio;
134	}
135
136	if (sg->length < TMIO_MMC_MIN_DMA_LEN) {
137		host->force_pio = true;
138		return;
139	}
140
141	tmio_mmc_disable_mmc_irqs(host, TMIO_STAT_TXRQ);
142
143	/* The only sg element can be unaligned, use our bounce buffer then */
144	if (!aligned) {
145		unsigned long flags;
146		void *sg_vaddr = tmio_mmc_kmap_atomic(sg, &flags);
147		sg_init_one(&host->bounce_sg, host->bounce_buf, sg->length);
148		memcpy(host->bounce_buf, sg_vaddr, host->bounce_sg.length);
149		tmio_mmc_kunmap_atomic(sg, &flags, sg_vaddr);
150		host->sg_ptr = &host->bounce_sg;
151		sg = host->sg_ptr;
152	}
153
154	ret = dma_map_sg(chan->device->dev, sg, host->sg_len, DMA_TO_DEVICE);
155	if (ret > 0)
156		desc = chan->device->device_prep_slave_sg(chan, sg, ret,
157			DMA_TO_DEVICE, DMA_CTRL_ACK);
158
159	if (desc) {
160		cookie = dmaengine_submit(desc);
161		if (cookie < 0) {
162			desc = NULL;
163			ret = cookie;
164		}
165	}
166	dev_dbg(&host->pdev->dev, "%s(): mapped %d -> %d, cookie %d, rq %p\n",
167		__func__, host->sg_len, ret, cookie, host->mrq);
168
169pio:
170	if (!desc) {
171		/* DMA failed, fall back to PIO */
172		if (ret >= 0)
173			ret = -EIO;
174		host->chan_tx = NULL;
175		dma_release_channel(chan);
176		/* Free the Rx channel too */
177		chan = host->chan_rx;
178		if (chan) {
179			host->chan_rx = NULL;
180			dma_release_channel(chan);
181		}
182		dev_warn(&host->pdev->dev,
183			 "DMA failed: %d, falling back to PIO\n", ret);
184		tmio_mmc_enable_dma(host, false);
185	}
186
187	dev_dbg(&host->pdev->dev, "%s(): desc %p, cookie %d\n", __func__,
188		desc, cookie);
189}
190
191void tmio_mmc_start_dma(struct tmio_mmc_host *host,
192			       struct mmc_data *data)
193{
194	if (data->flags & MMC_DATA_READ) {
195		if (host->chan_rx)
196			tmio_mmc_start_dma_rx(host);
197	} else {
198		if (host->chan_tx)
199			tmio_mmc_start_dma_tx(host);
200	}
201}
202
203static void tmio_mmc_issue_tasklet_fn(unsigned long priv)
204{
205	struct tmio_mmc_host *host = (struct tmio_mmc_host *)priv;
206	struct dma_chan *chan = NULL;
207
208	spin_lock_irq(&host->lock);
209
210	if (host && host->data) {
211		if (host->data->flags & MMC_DATA_READ)
212			chan = host->chan_rx;
213		else
214			chan = host->chan_tx;
215	}
216
217	spin_unlock_irq(&host->lock);
218
219	tmio_mmc_enable_mmc_irqs(host, TMIO_STAT_DATAEND);
220
221	if (chan)
222		dma_async_issue_pending(chan);
223}
224
225static void tmio_mmc_tasklet_fn(unsigned long arg)
226{
227	struct tmio_mmc_host *host = (struct tmio_mmc_host *)arg;
228
229	spin_lock_irq(&host->lock);
230
231	if (!host->data)
232		goto out;
233
234	if (host->data->flags & MMC_DATA_READ)
235		dma_unmap_sg(host->chan_rx->device->dev,
236			     host->sg_ptr, host->sg_len,
237			     DMA_FROM_DEVICE);
238	else
239		dma_unmap_sg(host->chan_tx->device->dev,
240			     host->sg_ptr, host->sg_len,
241			     DMA_TO_DEVICE);
242
243	tmio_mmc_do_data_irq(host);
244out:
245	spin_unlock_irq(&host->lock);
246}
247
248/* It might be necessary to make filter MFD specific */
249static bool tmio_mmc_filter(struct dma_chan *chan, void *arg)
250{
251	dev_dbg(chan->device->dev, "%s: slave data %p\n", __func__, arg);
252	chan->private = arg;
253	return true;
254}
255
256void tmio_mmc_request_dma(struct tmio_mmc_host *host, struct tmio_mmc_data *pdata)
257{
258	/* We can only either use DMA for both Tx and Rx or not use it at all */
259	if (!pdata->dma)
260		return;
261
262	if (!host->chan_tx && !host->chan_rx) {
263		dma_cap_mask_t mask;
264
265		dma_cap_zero(mask);
266		dma_cap_set(DMA_SLAVE, mask);
267
268		host->chan_tx = dma_request_channel(mask, tmio_mmc_filter,
269						    pdata->dma->chan_priv_tx);
270		dev_dbg(&host->pdev->dev, "%s: TX: got channel %p\n", __func__,
271			host->chan_tx);
272
273		if (!host->chan_tx)
274			return;
275
276		host->chan_rx = dma_request_channel(mask, tmio_mmc_filter,
277						    pdata->dma->chan_priv_rx);
278		dev_dbg(&host->pdev->dev, "%s: RX: got channel %p\n", __func__,
279			host->chan_rx);
280
281		if (!host->chan_rx)
282			goto ereqrx;
283
284		host->bounce_buf = (u8 *)__get_free_page(GFP_KERNEL | GFP_DMA);
285		if (!host->bounce_buf)
286			goto ebouncebuf;
287
288		tasklet_init(&host->dma_complete, tmio_mmc_tasklet_fn, (unsigned long)host);
289		tasklet_init(&host->dma_issue, tmio_mmc_issue_tasklet_fn, (unsigned long)host);
290	}
291
292	tmio_mmc_enable_dma(host, true);
293
294	return;
295
296ebouncebuf:
297	dma_release_channel(host->chan_rx);
298	host->chan_rx = NULL;
299ereqrx:
300	dma_release_channel(host->chan_tx);
301	host->chan_tx = NULL;
302}
303
304void tmio_mmc_release_dma(struct tmio_mmc_host *host)
305{
306	if (host->chan_tx) {
307		struct dma_chan *chan = host->chan_tx;
308		host->chan_tx = NULL;
309		dma_release_channel(chan);
310	}
311	if (host->chan_rx) {
312		struct dma_chan *chan = host->chan_rx;
313		host->chan_rx = NULL;
314		dma_release_channel(chan);
315	}
316	if (host->bounce_buf) {
317		free_pages((unsigned long)host->bounce_buf, 0);
318		host->bounce_buf = NULL;
319	}
320}