For example, with SDIO WLAN cards, some transfers happen with buffers at odd
addresses, whereas the SH-Mobile DMA engine requires even addresses for SDHI.
This patch extends the tmio driver with a bounce buffer, that is used for
single entry scatter-gather lists both for sending and receiving. If we ever
encounter unaligned transfers with multi-element sg lists, this patch will have
to be extended. For now it just falls back to PIO in this and other unsupported
cases.
Signed-off-by: Guennadi Liakhovetski <g.liakhovet...@gmx.de>
---
drivers/mmc/host/tmio_mmc.c | 81 +++++++++++++++++++++++++++++++++++++++----
include/linux/mfd/tmio.h | 1 +
2 files changed, 75 insertions(+), 7 deletions(-)
diff --git a/drivers/mmc/host/tmio_mmc.c b/drivers/mmc/host/tmio_mmc.c
index 118ad86..57ece9d 100644
--- a/drivers/mmc/host/tmio_mmc.c
+++ b/drivers/mmc/host/tmio_mmc.c
@@ -111,6 +111,8 @@
sd_ctrl_write32((host), CTL_STATUS, ~(i)); \
} while (0)
+/* This is arbitrary, just noone needed any higher alignment yet */
+#define MAX_ALIGN 4
struct tmio_mmc_host {
void __iomem *ctl;
@@ -127,6 +129,7 @@ struct tmio_mmc_host {
/* pio related stuff */
struct scatterlist *sg_ptr;
+ struct scatterlist *sg_orig;
unsigned int sg_len;
unsigned int sg_off;
@@ -139,6 +142,8 @@ struct tmio_mmc_host {
struct tasklet_struct dma_issue;
#ifdef CONFIG_TMIO_MMC_DMA
unsigned int dma_sglen;
+ u8 bounce_buf[PAGE_CACHE_SIZE]
__attribute__((aligned(MAX_ALIGN)));
+ struct scatterlist bounce_sg;
#endif
};
@@ -180,6 +185,7 @@ static void tmio_mmc_init_sg(struct tmio_mmc_host *host,
struct mmc_data *data)
{
host->sg_len = data->sg_len;
host->sg_ptr = data->sg;
+ host->sg_orig = data->sg;
host->sg_off = 0;
}
@@ -436,8 +442,14 @@ static void tmio_mmc_do_data_irq(struct tmio_mmc_host
*host)
*/
if (data->flags & MMC_DATA_READ) {
- if (!host->chan_rx)
+ if (!host->chan_rx) {
disable_mmc_irqs(host, TMIO_MASK_READOP);
+ } else if (host->sg_ptr == &host->bounce_sg) {
+ unsigned long flags;
+ void *sg_vaddr = tmio_mmc_kmap_atomic(host->sg_orig,
&flags);
+ memcpy(sg_vaddr, host->bounce_buf,
host->bounce_sg.length);
+ tmio_mmc_kunmap_atomic(sg_vaddr, &flags);
+ }
dev_dbg(&host->pdev->dev, "Complete Rx request %p\n",
host->mrq);
} else {
@@ -529,8 +541,7 @@ static void tmio_mmc_cmd_irq(struct tmio_mmc_host *host,
if (!host->chan_rx)
enable_mmc_irqs(host, TMIO_MASK_READOP);
} else {
- struct dma_chan *chan = host->chan_tx;
- if (!chan)
+ if (!host->chan_tx)
enable_mmc_irqs(host, TMIO_MASK_WRITEOP);
else
tasklet_schedule(&host->dma_issue);
@@ -634,11 +645,36 @@ static void tmio_dma_complete(void *arg)
static void tmio_mmc_start_dma_rx(struct tmio_mmc_host *host)
{
- struct scatterlist *sg = host->sg_ptr;
+ struct scatterlist *sg = host->sg_ptr, *sg_tmp;
struct dma_async_tx_descriptor *desc = NULL;
struct dma_chan *chan = host->chan_rx;
+ struct mfd_cell *cell = host->pdev->dev.platform_data;
+ struct tmio_mmc_data *pdata = cell->driver_data;
dma_cookie_t cookie;
- int ret;
+ 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 >= MAX_ALIGN)) || !multiple)
+ goto pio;
+
+ /* The only sg element can be unaligned, use our bounce buffer then */
+ if (!aligned) {
+ /* The first sg element unaligned, use our bounce-buffer */
+ 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(&host->pdev->dev, sg, host->sg_len, DMA_FROM_DEVICE);
if (ret > 0) {
@@ -661,6 +697,7 @@ static void tmio_mmc_start_dma_rx(struct tmio_mmc_host
*host)
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)
@@ -684,11 +721,40 @@ static void tmio_mmc_start_dma_rx(struct tmio_mmc_host
*host)
static void tmio_mmc_start_dma_tx(struct tmio_mmc_host *host)
{
- struct scatterlist *sg = host->sg_ptr;
+ struct scatterlist *sg = host->sg_ptr, *sg_tmp;
struct dma_async_tx_descriptor *desc = NULL;
struct dma_chan *chan = host->chan_tx;
+ struct mfd_cell *cell = host->pdev->dev.platform_data;
+ struct tmio_mmc_data *pdata = cell->driver_data;
dma_cookie_t cookie;
- int ret;
+ 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 >= MAX_ALIGN)) || !multiple)
+ goto pio;
+
+ /* 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);
+ /* The first sg element unaligned, use our bounce-buffer */
+ 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_vaddr, &flags);
+ host->sg_ptr = &host->bounce_sg;
+ sg = host->sg_ptr;
+ }
ret = dma_map_sg(&host->pdev->dev, sg, host->sg_len, DMA_TO_DEVICE);
if (ret > 0) {
@@ -709,6 +775,7 @@ static void tmio_mmc_start_dma_tx(struct tmio_mmc_host
*host)
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)
diff --git a/include/linux/mfd/tmio.h b/include/linux/mfd/tmio.h
index 085f041..dbfc053 100644
--- a/include/linux/mfd/tmio.h
+++ b/include/linux/mfd/tmio.h
@@ -66,6 +66,7 @@ void tmio_core_mmc_clk_div(void __iomem *cnf, int shift, int
state);
struct tmio_mmc_dma {
void *chan_priv_tx;
void *chan_priv_rx;
+ int alignment_shift;
};
/*
--
1.7.2.3
--
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