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Message-Id: <1294856383-14187-5-git-send-email-per.forlin@linaro.org>
Date: Wed, 12 Jan 2011 19:19:43 +0100
From: Per Forlin <per.forlin@...aro.org>
To: linux-mmc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org, linaro-dev@...ts.linaro.org
Cc: Chris Ball <cjb@...top.org>, Per Forlin <per.forlin@...aro.org>
Subject: [FYI 4/4] ARM: mmci: add support for double buffering
This is an example of how to utilize the double buffer
support in the mmc framework. This patch is not intended
nor ready for mainline.
Implement pre_req() and post_reg() hooks. pre_req()
runs dma_map_sg and prepares the dma descriptor and
post_req calls dma_unmap_sg.
Signed-off-by: Per Forlin <per.forlin@...aro.org>
---
drivers/mmc/host/mmci.c | 164 ++++++++++++++++++++++++++++++++++++-----------
drivers/mmc/host/mmci.h | 4 +
2 files changed, 130 insertions(+), 38 deletions(-)
diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
index ab44f5f..7f0b12a 100644
--- a/drivers/mmc/host/mmci.c
+++ b/drivers/mmc/host/mmci.c
@@ -276,6 +276,7 @@ static void __devinit mmci_setup_dma(struct mmci_host *host)
host->dma_tx_channel = host->dma_rx_channel;
}
host->dma_enable = true;
+
dev_info(mmc_dev(host->mmc), "use DMA channels DMA RX %s, DMA TX %s\n",
dma_chan_name(host->dma_rx_channel),
dma_chan_name(host->dma_tx_channel));
@@ -296,11 +297,6 @@ static inline void mmci_disable_dma(struct mmci_host *host)
static void mmci_dma_data_end(struct mmci_host *host)
{
- struct mmc_data *data = host->data;
-
- dma_unmap_sg(mmc_dev(host->mmc), data->sg, data->sg_len,
- (data->flags & MMC_DATA_WRITE)
- ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
host->dma_on_current_xfer = false;
}
@@ -353,7 +349,9 @@ static void mmci_dma_callback(void *arg)
spin_unlock_irqrestore(&host->lock, flags);
}
-static int mmci_dma_start_data(struct mmci_host *host, unsigned int datactrl)
+static struct dma_async_tx_descriptor *mmci_dma_cfg(struct mmc_data *data,
+ struct mmci_host *host,
+ struct dma_chan **chan_dma)
{
struct variant_data *variant = host->variant;
struct dma_slave_config rx_conf = {
@@ -368,19 +366,13 @@ static int mmci_dma_start_data(struct mmci_host *host, unsigned int datactrl)
.direction = DMA_TO_DEVICE,
.dst_maxburst = variant->fifohalfsize >> 2, /* # of words */
};
- struct mmc_data *data = host->data;
enum dma_data_direction direction;
struct dma_chan *chan;
struct dma_async_tx_descriptor *desc;
struct scatterlist *sg;
- dma_cookie_t cookie;
int i;
- unsigned int irqmask0;
int sg_len;
- datactrl |= MCI_DPSM_DMAENABLE;
- datactrl |= variant->dmareg_enable;
-
if (data->flags & MMC_DATA_READ) {
if (host->size <= variant->txsize_threshold)
rx_conf.src_maxburst = 1;
@@ -404,11 +396,12 @@ static int mmci_dma_start_data(struct mmci_host *host, unsigned int datactrl)
dev_vdbg(mmc_dev(host->mmc), "MMCI SGlist %d dir %d: length: %08x\n",
i, direction, sg->length);
if (sg->offset & 3 || sg->length & 3)
- return -EINVAL;
+ return NULL;
}
sg_len = dma_map_sg(mmc_dev(host->mmc), data->sg,
- data->sg_len, direction);
+ data->sg_len, direction);
+
if (!sg_len)
goto map_err;
@@ -420,7 +413,42 @@ static int mmci_dma_start_data(struct mmci_host *host, unsigned int datactrl)
desc->callback = mmci_dma_callback;
desc->callback_param = host;
- host->dma_desc = desc;
+
+ *chan_dma = chan;
+ return desc;
+unmap_exit:
+ dma_unmap_sg(mmc_dev(host->mmc), data->sg, data->sg_len, direction);
+map_err:
+ *chan_dma = NULL;
+ return NULL;
+}
+
+static void mmci_dma_prepare(struct mmc_data *data, struct mmci_host *host)
+{
+
+ if (data != host->data_next)
+ host->dma_desc = mmci_dma_cfg(data, host, &host->cur_chan);
+ else {
+ host->dma_desc = host->dma_desc_next;
+ host->cur_chan = host->next_chan;
+
+ host->dma_desc_next = NULL;
+ host->data_next = NULL;
+ host->next_chan = NULL;
+ }
+
+ BUG_ON(!host->dma_desc);
+ BUG_ON(!host->cur_chan);
+}
+
+static int mmci_dma_start_data(struct mmci_host *host)
+{
+ struct mmc_data *data = host->data;
+ struct dma_async_tx_descriptor *desc = host->dma_desc;
+ struct dma_chan *chan = host->cur_chan;
+ dma_cookie_t cookie;
+ enum dma_data_direction direction;
+
dev_vdbg(mmc_dev(host->mmc), "Submit MMCI DMA job, sglen %d "
"blksz %04x blks %04x flags %08x\n",
data->sg_len, data->blksz, data->blocks, data->flags);
@@ -433,6 +461,24 @@ static int mmci_dma_start_data(struct mmci_host *host, unsigned int datactrl)
host->dma_on_current_xfer = true;
chan->device->device_issue_pending(chan);
+ return 0;
+unmap_exit:
+ if (data->flags & MMC_DATA_READ)
+ direction = DMA_FROM_DEVICE;
+
+ dma_unmap_sg(mmc_dev(host->mmc), data->sg, data->sg_len, direction);
+ chan->device->device_control(chan, DMA_TERMINATE_ALL, 0);
+
+ return -ENOMEM;
+}
+
+static int mmci_dma_start_fifo(struct mmci_host *host, unsigned int datactrl)
+{
+ unsigned int irqmask0;
+
+ datactrl |= MCI_DPSM_DMAENABLE;
+ datactrl |= host->variant->dmareg_enable;
+
/*
* MMCI monitors both MCI_DATAEND and the DMA callback.
* Both events must occur before the transfer is considered
@@ -447,12 +493,45 @@ static int mmci_dma_start_data(struct mmci_host *host, unsigned int datactrl)
/* Trigger the DMA transfer */
writel(datactrl, host->base + MMCIDATACTRL);
return 0;
+}
+
+static void mmci_post_request(struct mmc_host *mmc, struct mmc_request *mrq)
+{
+ struct mmci_host *host = mmc_priv(mmc);
+ struct mmc_data *data = mrq->data;
+
+ if (host->dma_enable)
+ dma_unmap_sg(mmc_dev(host->mmc), data->sg, data->sg_len,
+ (data->flags & MMC_DATA_WRITE)
+ ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
+}
+
+static void mmci_pre_request(struct mmc_host *mmc, struct mmc_request *mrq,
+ bool host_is_idle)
+{
+ struct mmci_host *host = mmc_priv(mmc);
+ struct mmc_data *data = mrq->data;
+
+ if (host->dma_enable && !host_is_idle) {
+ struct dma_async_tx_descriptor *desc;
+ struct dma_chan *chan;
+
+ desc = mmci_dma_cfg(data, host, &chan);
+ if (desc == NULL)
+ goto no_next;
+
+ host->dma_desc_next = desc;
+ host->data_next = data;
+ host->next_chan = chan;
+ }
+
+ return;
+
+ no_next:
+ host->dma_desc_next = NULL;
+ host->data_next = NULL;
+ host->next_chan = NULL;
-unmap_exit:
- dma_unmap_sg(mmc_dev(host->mmc), data->sg, data->sg_len, direction);
-map_err:
- chan->device->device_control(chan, DMA_TERMINATE_ALL, 0);
- return -ENOMEM;
}
#else
/* Blank functions if the DMA engine is not available */
@@ -472,10 +551,23 @@ static inline void mmci_dma_terminate(struct mmci_host *host)
{
}
-static inline int mmci_dma_start_data(struct mmci_host *host, unsigned int datactrl)
+static inline int mmci_dma_start_data(struct mmci_host *host)
{
return -ENOSYS;
}
+
+static inline int mmci_dma_start_fifo(struct mmci_host *host,
+ unsigned int datactrl)
+{
+ return -ENOSYS;
+}
+
+static void mmci_dma_prepare(struct mmc_data *data, struct mmci_host *host)
+{
+}
+
+#define mmci_post_request NULL
+#define mmci_pre_request NULL
#endif
static void mmci_start_data(struct mmci_host *host, struct mmc_data *data)
@@ -519,7 +611,7 @@ static void mmci_start_data(struct mmci_host *host, struct mmc_data *data)
* Attempt to use DMA operation mode, if this
* should fail, fall back to PIO mode
*/
- ret = mmci_dma_start_data(host, datactrl);
+ ret = mmci_dma_start_fifo(host, datactrl);
if (!ret)
return;
}
@@ -662,13 +754,6 @@ mmci_data_irq(struct mmci_host *host, struct mmc_data *data,
mmci_stop_data(host);
host->dataend = false;
- /*
- * Variants with broken blockend flags need to handle
- * the end of the entire transfer here.
- */
- if (variant->broken_blockend && !data->error)
- host->data_xfered += data->blksz * data->blocks;
-
if (!data->stop)
mmci_request_end(host, data->mrq);
else
@@ -705,6 +790,8 @@ mmci_cmd_irq(struct mmci_host *host, struct mmc_command *cmd,
mmci_request_end(host, cmd->mrq);
} else if (!(cmd->data->flags & MMC_DATA_READ)) {
mmci_start_data(host, cmd->data);
+ if (host->dma_enable)
+ mmci_dma_start_data(host);
}
}
@@ -944,6 +1031,13 @@ static void mmci_request(struct mmc_host *mmc, struct mmc_request *mrq)
mmci_start_command(host, mrq->cmd, 0);
+ if (host->dma_enable && mrq->data) {
+ mmci_dma_prepare(mrq->data, host);
+
+ if (mrq->data->flags & MMC_DATA_READ)
+ mmci_dma_start_data(host);
+ }
+
spin_unlock_irqrestore(&host->lock, flags);
}
@@ -1053,6 +1147,8 @@ static irqreturn_t mmci_cd_irq(int irq, void *dev_id)
static const struct mmc_host_ops mmci_ops = {
.request = mmci_request,
+ .pre_req = mmci_pre_request,
+ .post_req = mmci_post_request,
.set_ios = mmci_set_ios,
.get_ro = mmci_get_ro,
.get_cd = mmci_get_cd,
@@ -1180,15 +1276,7 @@ static int __devinit mmci_probe(struct amba_device *dev, struct amba_id *id)
* single request.
*/
mmc->max_req_size = (1 << variant->datalength_bits) - 1;
-
- /*
- * Set the maximum segment size. Right now DMA sets the
- * limit and not the data length register. Thus until the DMA
- * driver not handles this, the segment size is limited by DMA.
- * DMA limit: src_addr_width x (64 KB -1). src_addr_width
- * can be 1.
- */
- mmc->max_seg_size = 65535;
+ mmc->max_seg_size = mmc->max_req_size;
/*
* Block size can be up to 2048 bytes, but must be a power of two.
diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
index 39b7ac7..828ab5a 100644
--- a/drivers/mmc/host/mmci.h
+++ b/drivers/mmc/host/mmci.h
@@ -196,6 +196,10 @@ struct mmci_host {
struct dma_chan *dma_rx_channel;
struct dma_chan *dma_tx_channel;
struct dma_async_tx_descriptor *dma_desc;
+ struct dma_async_tx_descriptor *dma_desc_next;
+ struct mmc_data *data_next;
+ struct dma_chan *cur_chan;
+ struct dma_chan *next_chan;
#endif
};
--
1.7.1
--
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