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.liakhovetski@xxxxxx>
---
Chris, thanks for your comments, but you picked up a wrong version of this
patch. Please, use links from my "outstanding patches" email.
v3:
1. wrapped patch description at 72 chars instead of 80
2. removed two redundant comment lines
v2:
1. fixed compilation without DMA support. Thanks to Magnus Damm
<damm@xxxxxxxxxxxxx> for reporting
drivers/mmc/host/tmio_mmc.c | 89 ++++++++++++++++++++++++++++++++++++++++---
include/linux/mfd/tmio.h | 1 +
2 files changed, 84 insertions(+), 6 deletions(-)
diff --git a/drivers/mmc/host/tmio_mmc.c b/drivers/mmc/host/tmio_mmc.c
index 118ad86..d8163c1 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;
@@ -139,9 +142,13 @@ 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
};
+static void tmio_check_bounce_buffer(struct tmio_mmc_host *host);
+
static u16 sd_ctrl_read16(struct tmio_mmc_host *host, int addr)
{
return readw(host->ctl + (addr << host->bus_shift));
@@ -180,6 +187,7 @@ 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;
}
@@ -438,6 +446,8 @@ static void tmio_mmc_do_data_irq(struct tmio_mmc_host *host)
if (data->flags & MMC_DATA_READ) {
if (!host->chan_rx)
disable_mmc_irqs(host, TMIO_MASK_READOP);
+ else
+ tmio_check_bounce_buffer(host);
dev_dbg(&host->pdev->dev, "Complete Rx request %p\n",
host->mrq);
} else {
@@ -529,8 +539,7 @@ 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);
@@ -612,6 +621,16 @@ out:
}
#ifdef CONFIG_TMIO_MMC_DMA
+static void tmio_check_bounce_buffer(struct tmio_mmc_host *host)
+{
+ 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);
+ }
+}
+
static void tmio_mmc_enable_dma(struct tmio_mmc_host *host, bool enable)
{
#if defined(CONFIG_SUPERH) || defined(CONFIG_ARCH_SHMOBILE)
@@ -634,11 +653,35 @@ 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) {
+ 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 +704,7 @@ 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 +728,39 @@ 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);
+ 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 +781,7 @@ 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)
@@ -822,6 +895,10 @@ static void tmio_mmc_release_dma(struct tmio_mmc_host *host)
}
}
#else
+static void tmio_check_bounce_buffer(struct tmio_mmc_host *host)
+{
+}
+
static void tmio_mmc_start_dma(struct tmio_mmc_host *host,
struct mmc_data *data)
{
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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