- 根目录:
- drivers
- mmc
- host
- tmio_mmc_dma.c
/*
* linux/drivers/mmc/tmio_mmc_dma.c
*
* Copyright (C) 2010-2011 Guennadi Liakhovetski
*
* 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.
*
* DMA function for TMIO MMC implementations
*/
#include <linux/device.h>
#include <linux/dmaengine.h>
#include <linux/mfd/tmio.h>
#include <linux/mmc/host.h>
#include <linux/mmc/tmio.h>
#include <linux/pagemap.h>
#include <linux/scatterlist.h>
#include "tmio_mmc.h"
#define TMIO_MMC_MIN_DMA_LEN 8
static void tmio_mmc_enable_dma(struct tmio_mmc_host *host, bool enable)
{
#if defined(CONFIG_SUPERH) || defined(CONFIG_ARCH_SHMOBILE)
/* Switch DMA mode on or off - SuperH specific? */
writew(enable ? 2 : 0, host->ctl + (0xd8 << host->bus_shift));
#endif
}
static void tmio_mmc_start_dma_rx(struct tmio_mmc_host *host)
{
struct scatterlist *sg = host->sg_ptr, *sg_tmp;
struct dma_async_tx_descriptor *desc = NULL;
struct dma_chan *chan = host->chan_rx;
struct tmio_mmc_data *pdata = host->pdata;
dma_cookie_t cookie;
int ret, i;
bool aligned = true, multiple = true;
unsigned int align = (1 << pdata->dma->alignment_shift) - 1;
for_each_sg(sg, sg_tmp, host->sg_len, i) {
if (sg_tmp->offset & align)
aligned = false;
if (sg_tmp->length & align) {
multiple = false;
break;
}
}
if ((!aligned && (host->sg_len > 1 || sg->length > PAGE_CACHE_SIZE ||
(align & PAGE_MASK))) || !multiple) {
ret = -EINVAL;
goto pio;
}
if (sg->length < TMIO_MMC_MIN_DMA_LEN) {
host->force_pio = true;
return;
}
tmio_mmc_disable_mmc_irqs(host, TMIO_STAT_RXRDY);
/* The only sg element can be unaligned, use our bounce buffer then */
if (!aligned) {
sg_init_one(&host->bounce_sg, host->bounce_buf, sg->length);
host->sg_ptr = &host->bounce_sg;
sg = host->sg_ptr;
}
ret = dma_map_sg(chan->device->dev, sg, host->sg_len, DMA_FROM_DEVICE);
if (ret > 0)
desc = chan->device->device_prep_slave_sg(chan, sg, ret,
DMA_FROM_DEVICE, DMA_CTRL_ACK);
if (desc) {
cookie = dmaengine_submit(desc);
if (cookie < 0) {
desc = NULL;
ret = cookie;
}
}
dev_dbg(&host->pdev->dev, "%s(): mapped %d -> %d, cookie %d, rq %p\n",
__func__, host->sg_len, ret, cookie, host->mrq);
pio:
if (!desc) {
/* DMA failed, fall back to PIO */
if (ret >= 0)
ret = -EIO;
host->chan_rx = NULL;
dma_release_channel(chan);
/* Free the Tx channel too */
chan = host->chan_tx;
if (chan) {
host->chan_tx = NULL;
dma_release_channel(chan);
}
dev_warn(&host->pdev->dev,
"DMA failed: %d, falling back to PIO\n", ret);
tmio_mmc_enable_dma(host, false);
}
dev_dbg(&host->pdev->dev, "%s(): desc %p, cookie %d, sg[%d]\n", __func__,
desc, cookie, host->sg_len);
}
static void tmio_mmc_start_dma_tx(struct tmio_mmc_host *host)
{
struct scatterlist *sg = host->sg_ptr, *sg_tmp;
struct dma_async_tx_descriptor *desc = NULL;
struct dma_chan *chan = host->chan_tx;
struct tmio_mmc_data *pdata = host->pdata;
dma_cookie_t cookie;
int ret, i;
bool aligned = true, multiple = true;
unsigned int align = (1 << pdata->dma->alignment_shift) - 1;
for_each_sg(sg, sg_tmp, host->sg_len, i) {
if (sg_tmp->offset & align)
aligned = false;
if (sg_tmp->length & align) {
multiple = false;
break;
}
}
if ((!aligned && (host->sg_len > 1 || sg->length > PAGE_CACHE_SIZE ||
(align & PAGE_MASK))) || !multiple) {
ret = -EINVAL;
goto pio;
}
if (sg->length < TMIO_MMC_MIN_DMA_LEN) {
host->force_pio = true;
return;
}
tmio_mmc_disable_mmc_irqs(host, TMIO_STAT_TXRQ);
/* The only sg element can be unaligned, use our bounce buffer then */
if (!aligned) {
unsigned long flags;
void *sg_vaddr = tmio_mmc_kmap_atomic(sg, &flags);
sg_init_one(&host->bounce_sg, host->bounce_buf, sg->length);
memcpy(host->bounce_buf, sg_vaddr, host->bounce_sg.length);
tmio_mmc_kunmap_atomic(sg, &flags, sg_vaddr);
host->sg_ptr = &host->bounce_sg;
sg = host->sg_ptr;
}
ret = dma_map_sg(chan->device->dev, sg, host->sg_len, DMA_TO_DEVICE);
if (ret > 0)
desc = chan->device->device_prep_slave_sg(chan, sg, ret,
DMA_TO_DEVICE, DMA_CTRL_ACK);
if (desc) {
cookie = dmaengine_submit(desc);
if (cookie < 0) {
desc = NULL;
ret = cookie;
}
}
dev_dbg(&host->pdev->dev, "%s(): mapped %d -> %d, cookie %d, rq %p\n",
__func__, host->sg_len, ret, cookie, host->mrq);
pio:
if (!desc) {
/* DMA failed, fall back to PIO */
if (ret >= 0)
ret = -EIO;
host->chan_tx = NULL;
dma_release_channel(chan);
/* Free the Rx channel too */
chan = host->chan_rx;
if (chan) {
host->chan_rx = NULL;
dma_release_channel(chan);
}
dev_warn(&host->pdev->dev,
"DMA failed: %d, falling back to PIO\n", ret);
tmio_mmc_enable_dma(host, false);
}
dev_dbg(&host->pdev->dev, "%s(): desc %p, cookie %d\n", __func__,
desc, cookie);
}
void tmio_mmc_start_dma(struct tmio_mmc_host *host,
struct mmc_data *data)
{
if (data->flags & MMC_DATA_READ) {
if (host->chan_rx)
tmio_mmc_start_dma_rx(host);
} else {
if (host->chan_tx)
tmio_mmc_start_dma_tx(host);
}
}
static void tmio_mmc_issue_tasklet_fn(unsigned long priv)
{
struct tmio_mmc_host *host = (struct tmio_mmc_host *)priv;
struct dma_chan *chan = NULL;
spin_lock_irq(&host->lock);
if (host && host->data) {
if (host->data->flags & MMC_DATA_READ)
chan = host->chan_rx;
else
chan = host->chan_tx;
}
spin_unlock_irq(&host->lock);
tmio_mmc_enable_mmc_irqs(host, TMIO_STAT_DATAEND);
if (chan)
dma_async_issue_pending(chan);
}
static void tmio_mmc_tasklet_fn(unsigned long arg)
{
struct tmio_mmc_host *host = (struct tmio_mmc_host *)arg;
spin_lock_irq(&host->lock);
if (!host->data)
goto out;
if (host->data->flags & MMC_DATA_READ)
dma_unmap_sg(host->chan_rx->device->dev,
host->sg_ptr, host->sg_len,
DMA_FROM_DEVICE);
else
dma_unmap_sg(host->chan_tx->device->dev,
host->sg_ptr, host->sg_len,
DMA_TO_DEVICE);
tmio_mmc_do_data_irq(host);
out:
spin_unlock_irq(&host->lock);
}
/* It might be necessary to make filter MFD specific */
static bool tmio_mmc_filter(struct dma_chan *chan, void *arg)
{
dev_dbg(chan->device->dev, "%s: slave data %p\n", __func__, arg);
chan->private = arg;
return true;
}
void tmio_mmc_request_dma(struct tmio_mmc_host *host, struct tmio_mmc_data *pdata)
{
/* We can only either use DMA for both Tx and Rx or not use it at all */
if (pdata->dma) {
dma_cap_mask_t mask;
dma_cap_zero(mask);
dma_cap_set(DMA_SLAVE, mask);
host->chan_tx = dma_request_channel(mask, tmio_mmc_filter,
pdata->dma->chan_priv_tx);
dev_dbg(&host->pdev->dev, "%s: TX: got channel %p\n", __func__,
host->chan_tx);
if (!host->chan_tx)
return;
host->chan_rx = dma_request_channel(mask, tmio_mmc_filter,
pdata->dma->chan_priv_rx);
dev_dbg(&host->pdev->dev, "%s: RX: got channel %p\n", __func__,
host->chan_rx);
if (!host->chan_rx)
goto ereqrx;
host->bounce_buf = (u8 *)__get_free_page(GFP_KERNEL | GFP_DMA);
if (!host->bounce_buf)
goto ebouncebuf;
tasklet_init(&host->dma_complete, tmio_mmc_tasklet_fn, (unsigned long)host);
tasklet_init(&host->dma_issue, tmio_mmc_issue_tasklet_fn, (unsigned long)host);
tmio_mmc_enable_dma(host, true);
return;
ebouncebuf:
dma_release_channel(host->chan_rx);
host->chan_rx = NULL;
ereqrx:
dma_release_channel(host->chan_tx);
host->chan_tx = NULL;
return;
}
}
void tmio_mmc_release_dma(struct tmio_mmc_host *host)
{
if (host->chan_tx) {
struct dma_chan *chan = host->chan_tx;
host->chan_tx = NULL;
dma_release_channel(chan);
}
if (host->chan_rx) {
struct dma_chan *chan = host->chan_rx;
host->chan_rx = NULL;
dma_release_channel(chan);
}
if (host->bounce_buf) {
free_pages((unsigned long)host->bounce_buf, 0);
host->bounce_buf = NULL;
}
}