[PATCH 18/18] fsmc/nand: Add DMA support
Vipin Kumar
vipin.kumar at st.com
Wed Mar 7 06:31:06 EST 2012
The fsmc_nand driver uses cpu to read/write onto the device. This is inefficient
because of two reasons
- the cpu gets locked on AHB bus while reading from NAND
- the cpu is unnecessarily used when dma can do the job
This patch adds the support for accessing the device through DMA
Signed-off-by: Vipin Kumar <vipin.kumar at st.com>
Reviewed-by: Viresh Kumar <viresh.kumar at st.com>
---
drivers/mtd/nand/fsmc_nand.c | 173 ++++++++++++++++++++++++++++++++++++++++-
include/linux/mtd/fsmc.h | 4 +
2 files changed, 172 insertions(+), 5 deletions(-)
diff --git a/drivers/mtd/nand/fsmc_nand.c b/drivers/mtd/nand/fsmc_nand.c
index 3828279..5cc79bc 100644
--- a/drivers/mtd/nand/fsmc_nand.c
+++ b/drivers/mtd/nand/fsmc_nand.c
@@ -17,6 +17,10 @@
*/
#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-direction.h>
+#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/module.h>
@@ -452,6 +456,11 @@ static struct mtd_partition partition_info_2048KB_blk[] = {
* @bank: Bank number for probed device.
* @clk: Clock structure for FSMC.
*
+ * @read_dma_chan: DMA channel for read access
+ * @write_dma_chan: DMA channel for write access to NAND
+ * @dma_access_complete: Completion structure
+ *
+ * @data_pa: NAND Physical port for Data.
* @data_va: NAND port for Data.
* @cmd_va: NAND port for Command.
* @addr_va: NAND port for Address.
@@ -465,10 +474,17 @@ struct fsmc_nand_data {
struct fsmc_eccplace *ecc_place;
unsigned int bank;
struct device *dev;
+ enum access_mode mode;
struct clk *clk;
+ /* DMA related objects */
+ struct dma_chan *read_dma_chan;
+ struct dma_chan *write_dma_chan;
+ struct completion dma_access_complete;
+
struct fsmc_nand_timings *dev_timings;
+ dma_addr_t data_pa;
void __iomem *data_va;
void __iomem *cmd_va;
void __iomem *addr_va;
@@ -691,6 +707,82 @@ static int count_written_bits(uint8_t *buff, int size, int max_bits)
return written_bits;
}
+static void dma_complete(void *param)
+{
+ struct fsmc_nand_data *host = param;
+
+ complete(&host->dma_access_complete);
+}
+
+static int dma_xfer(struct fsmc_nand_data *host, void *buffer, int len,
+ enum dma_data_direction direction)
+{
+ struct dma_chan *chan;
+ struct dma_device *dma_dev;
+ struct dma_async_tx_descriptor *tx;
+ dma_addr_t dma_dst, dma_src, dma_addr;
+ dma_cookie_t cookie;
+ unsigned long flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
+ int ret;
+
+ if (direction == DMA_TO_DEVICE)
+ chan = host->write_dma_chan;
+ else if (direction == DMA_FROM_DEVICE)
+ chan = host->read_dma_chan;
+ else
+ return -EINVAL;
+
+ dma_dev = chan->device;
+ dma_addr = dma_map_single(dma_dev->dev, buffer, len, direction);
+
+ if (direction == DMA_TO_DEVICE) {
+ dma_src = dma_addr;
+ dma_dst = host->data_pa;
+ flags |= DMA_COMPL_SRC_UNMAP_SINGLE | DMA_COMPL_SKIP_DEST_UNMAP;
+ } else {
+ dma_src = host->data_pa;
+ dma_dst = dma_addr;
+ flags |= DMA_COMPL_DEST_UNMAP_SINGLE | DMA_COMPL_SKIP_SRC_UNMAP;
+ }
+
+ tx = dma_dev->device_prep_dma_memcpy(chan, dma_dst, dma_src,
+ len, flags);
+
+ if (!tx) {
+ dev_err(host->dev, "device_prep_dma_memcpy error\n");
+ dma_unmap_single(dma_dev->dev, dma_addr, len, direction);
+ return -EIO;
+ }
+
+ tx->callback = dma_complete;
+ tx->callback_param = host;
+ cookie = tx->tx_submit(tx);
+
+ ret = dma_submit_error(cookie);
+ if (ret) {
+ dev_err(host->dev, "dma_submit_error %d\n", cookie);
+ return ret;
+ }
+
+ dma_async_issue_pending(chan);
+
+ ret =
+ wait_for_completion_interruptible_timeout(&host->dma_access_complete,
+ msecs_to_jiffies(3000));
+ if (ret <= 0) {
+ chan->device->device_control(chan, DMA_TERMINATE_ALL, 0);
+ dev_err(host->dev, "wait_for_completion_timeout\n");
+ return ret ? ret : -ETIMEDOUT;
+ }
+
+ preempt_disable();
+ __this_cpu_add(chan->local->bytes_transferred, len);
+ __this_cpu_inc(chan->local->memcpy_count);
+ preempt_enable();
+
+ return 0;
+}
+
/*
* fsmc_write_buf - write buffer to chip
* @mtd: MTD device structure
@@ -738,6 +830,35 @@ static void fsmc_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
}
/*
+ * fsmc_read_buf_dma - read chip data into buffer
+ * @mtd: MTD device structure
+ * @buf: buffer to store date
+ * @len: number of bytes to read
+ */
+static void fsmc_read_buf_dma(struct mtd_info *mtd, uint8_t *buf, int len)
+{
+ struct fsmc_nand_data *host;
+
+ host = container_of(mtd, struct fsmc_nand_data, mtd);
+ dma_xfer(host, buf, len, DMA_FROM_DEVICE);
+}
+
+/*
+ * fsmc_write_buf_dma - write buffer to chip
+ * @mtd: MTD device structure
+ * @buf: data buffer
+ * @len: number of bytes to write
+ */
+static void fsmc_write_buf_dma(struct mtd_info *mtd, const uint8_t *buf,
+ int len)
+{
+ struct fsmc_nand_data *host;
+
+ host = container_of(mtd, struct fsmc_nand_data, mtd);
+ dma_xfer(host, (void *)buf, len, DMA_TO_DEVICE);
+}
+
+/*
* fsmc_read_page_hwecc
* @mtd: mtd info structure
* @chip: nand chip info structure
@@ -899,6 +1020,12 @@ static int fsmc_bch8_correct_data(struct mtd_info *mtd, uint8_t *dat,
return i;
}
+static bool filter(struct dma_chan *chan, void *slave)
+{
+ chan->private = slave;
+ return true;
+}
+
/*
* fsmc_nand_probe - Probe function
* @pdev: platform device structure
@@ -912,6 +1039,7 @@ static int __init fsmc_nand_probe(struct platform_device *pdev)
struct fsmc_regs *regs;
struct resource *res;
struct mtd_partition *parts;
+ dma_cap_mask_t mask;
int nr_parts;
int ret = 0;
u32 pid;
@@ -939,6 +1067,7 @@ static int __init fsmc_nand_probe(struct platform_device *pdev)
return -ENOENT;
}
+ host->data_pa = (dma_addr_t)res->start;
host->data_va = devm_ioremap(&pdev->dev, res->start,
resource_size(res));
if (!host->data_va) {
@@ -1015,6 +1144,11 @@ static int __init fsmc_nand_probe(struct platform_device *pdev)
host->select_chip = pdata->select_bank;
host->dev = &pdev->dev;
host->dev_timings = pdata->nand_timings;
+ host->mode = pdata->mode;
+
+ if (host->mode == USE_DMA_ACCESS)
+ init_completion(&host->dma_access_complete);
+
regs = host->regs_va;
/* Link all private pointers */
@@ -1039,13 +1173,31 @@ static int __init fsmc_nand_probe(struct platform_device *pdev)
if (pdata->width == FSMC_NAND_BW16)
nand->options |= NAND_BUSWIDTH_16;
- /*
- * use customized (word by word) version of read_buf, write_buf if
- * access_with_dev_width is reset supported
- */
- if (pdata->mode == USE_WORD_ACCESS) {
+ switch (host->mode) {
+ case USE_DMA_ACCESS:
+ dma_cap_zero(mask);
+ dma_cap_set(DMA_MEMCPY, mask);
+ host->read_dma_chan = dma_request_channel(mask, filter,
+ pdata->read_dma_priv);
+ if (!host->read_dma_chan) {
+ dev_err(&pdev->dev, "Unable to get read dma channel\n");
+ goto err_req_read_chnl;
+ }
+ host->write_dma_chan = dma_request_channel(mask, filter,
+ pdata->write_dma_priv);
+ if (!host->write_dma_chan) {
+ dev_err(&pdev->dev, "Unable to get write dma channel\n");
+ goto err_req_write_chnl;
+ }
+ nand->read_buf = fsmc_read_buf_dma;
+ nand->write_buf = fsmc_write_buf_dma;
+ break;
+
+ default:
+ case USE_WORD_ACCESS:
nand->read_buf = fsmc_read_buf;
nand->write_buf = fsmc_write_buf;
+ break;
}
fsmc_nand_setup(regs, host->bank, nand->options & NAND_BUSWIDTH_16,
@@ -1177,6 +1329,12 @@ static int __init fsmc_nand_probe(struct platform_device *pdev)
err_probe:
err_scan_ident:
+ if (host->mode == USE_DMA_ACCESS)
+ dma_release_channel(host->write_dma_chan);
+err_req_write_chnl:
+ if (host->mode == USE_DMA_ACCESS)
+ dma_release_channel(host->read_dma_chan);
+err_req_read_chnl:
clk_disable(host->clk);
err_clk_enable:
clk_put(host->clk);
@@ -1194,6 +1352,11 @@ static int fsmc_nand_remove(struct platform_device *pdev)
if (host) {
nand_release(&host->mtd);
+
+ if (host->mode == USE_DMA_ACCESS) {
+ dma_release_channel(host->write_dma_chan);
+ dma_release_channel(host->read_dma_chan);
+ }
clk_disable(host->clk);
clk_put(host->clk);
}
diff --git a/include/linux/mtd/fsmc.h b/include/linux/mtd/fsmc.h
index 1edd2b3..18f9127 100644
--- a/include/linux/mtd/fsmc.h
+++ b/include/linux/mtd/fsmc.h
@@ -172,6 +172,10 @@ struct fsmc_nand_platform_data {
enum access_mode mode;
void (*select_bank)(uint32_t bank, uint32_t busw);
+
+ /* priv structures for dma accesses */
+ void *read_dma_priv;
+ void *write_dma_priv;
};
extern int __init fsmc_nor_init(struct platform_device *pdev,
--
1.7.0.4
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