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Subject[PATCH] MTD: atmel_nand: Add DMA support to access Nandflash
Date
Some SAM9 chips have the ability to perform DMA between CPU and SMC controller.
This patch adds DMA support for SAM9RL, SAM9G45, SSAM9G46,AM9M10, SAM9M11.

Signed-off-by: Hong Xu <hong.xu@atmel.com>
---
drivers/mtd/nand/atmel_nand.c | 160 ++++++++++++++++++++++++++++++++++++++++-
1 files changed, 158 insertions(+), 2 deletions(-)
diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
index ccce0f0..ba59913 100644
--- a/drivers/mtd/nand/atmel_nand.c
+++ b/drivers/mtd/nand/atmel_nand.c
@@ -48,6 +48,9 @@
#define no_ecc 0
#endif

+static int use_dma = 1;
+module_param(use_dma, int, 0);
+
static int on_flash_bbt = 0;
module_param(on_flash_bbt, int, 0);

@@ -89,11 +92,21 @@ struct atmel_nand_host {
struct nand_chip nand_chip;
struct mtd_info mtd;
void __iomem *io_base;
+ dma_addr_t io_phys;
struct atmel_nand_data *board;
struct device *dev;
void __iomem *ecc;
+
+ int dma_ready;
+ struct completion comp;
+ struct dma_chan *dma_chan;
};

+static int cpu_has_dma(void)
+{
+ return cpu_is_at91sam9rl() || cpu_is_at91sam9g45();
+}
+
/*
* Enable NAND.
*/
@@ -150,7 +163,7 @@ static int atmel_nand_device_ready(struct mtd_info *mtd)
/*
* Minimal-overhead PIO for data access.
*/
-static void atmel_read_buf(struct mtd_info *mtd, u8 *buf, int len)
+static void atmel_read_buf8(struct mtd_info *mtd, u8 *buf, int len)
{
struct nand_chip *nand_chip = mtd->priv;

@@ -164,7 +177,7 @@ static void atmel_read_buf16(struct mtd_info *mtd, u8 *buf, int len)
__raw_readsw(nand_chip->IO_ADDR_R, buf, len / 2);
}

-static void atmel_write_buf(struct mtd_info *mtd, const u8 *buf, int len)
+static void atmel_write_buf8(struct mtd_info *mtd, const u8 *buf, int len)
{
struct nand_chip *nand_chip = mtd->priv;

@@ -178,6 +191,123 @@ static void atmel_write_buf16(struct mtd_info *mtd, const u8 *buf, int len)
__raw_writesw(nand_chip->IO_ADDR_W, buf, len / 2);
}

+static void dma_complete_func(void *completion)
+{
+ complete(completion);
+}
+
+static int atmel_nand_dma_op(struct mtd_info *mtd, void *buf, int len,
+ int is_read)
+{
+ struct dma_device *dma_dev;
+ enum dma_ctrl_flags flags;
+ dma_addr_t dma_src_addr, dma_dst_addr, phys_addr;
+ struct dma_async_tx_descriptor *tx = NULL;
+ dma_cookie_t cookie;
+ struct nand_chip *chip = mtd->priv;
+ struct atmel_nand_host *host = chip->priv;
+ void *p = buf;
+
+ if (buf >= high_memory) {
+ struct page *pg;
+
+ if (((size_t)buf & PAGE_MASK) !=
+ ((size_t)(buf + len - 1) & PAGE_MASK))
+ goto err_dma;
+
+ pg = vmalloc_to_page(buf);
+ if (pg == 0)
+ goto err_dma;
+ p = page_address(pg) + ((size_t)buf & ~PAGE_MASK);
+ }
+
+ dma_dev = host->dma_chan->device;
+
+ flags = DMA_CTRL_ACK | DMA_COMPL_SKIP_DEST_UNMAP | DMA_PREP_INTERRUPT |
+ DMA_COMPL_SKIP_SRC_UNMAP;
+
+ if (is_read)
+ phys_addr = dma_map_single(dma_dev->dev, p, len,
+ DMA_FROM_DEVICE);
+ else
+ phys_addr = dma_map_single(dma_dev->dev, p, len,
+ DMA_TO_DEVICE);
+ if (dma_mapping_error(dma_dev->dev, phys_addr)) {
+ dev_err(host->dev, "Failed to dma_map_single\n");
+ goto err_dma;
+ }
+
+ if (is_read) {
+ dma_src_addr = host->io_phys;
+ dma_dst_addr = phys_addr;
+ } else {
+ dma_src_addr = phys_addr;
+ dma_dst_addr = host->io_phys;
+ }
+
+ tx = dma_dev->device_prep_dma_memcpy(host->dma_chan, dma_dst_addr,
+ dma_src_addr, len, flags);
+ if (!tx) {
+ dev_err(host->dev, "Failed to prepare DMA memcpy\n");
+ goto err;
+ }
+
+ init_completion(&host->comp);
+ tx->callback = dma_complete_func;
+ tx->callback_param = &host->comp;
+
+ cookie = tx->tx_submit(tx);
+ if (dma_submit_error(cookie)) {
+ dev_err(host->dev, "Failed to do DMA tx_submit\n");
+ goto err;
+ }
+
+ dma_async_issue_pending(host->dma_chan);
+
+ wait_for_completion(&host->comp);
+
+ return 0;
+
+err:
+ if (is_read)
+ dma_unmap_single(dma_dev->dev, phys_addr, len, DMA_FROM_DEVICE);
+ else
+ dma_unmap_single(dma_dev->dev, phys_addr, len, DMA_TO_DEVICE);
+err_dma:
+ /* Fall back to CPU I/O */
+ return -1;
+}
+
+static void atmel_read_buf(struct mtd_info *mtd, u8 *buf, int len)
+{
+ struct nand_chip *chip = mtd->priv;
+ struct atmel_nand_host *host = chip->priv;
+
+ if (host->dma_ready && len >= mtd->oobsize)
+ if (atmel_nand_dma_op(mtd, buf, len, 1) == 0)
+ return;
+
+ if (host->board->bus_width_16)
+ atmel_read_buf16(mtd, buf, len);
+ else
+ atmel_read_buf8(mtd, buf, len);
+}
+
+static void atmel_write_buf(struct mtd_info *mtd, const u8 *buf, int len)
+{
+ struct nand_chip *chip = mtd->priv;
+ struct atmel_nand_host *host = chip->priv;
+
+ if (host->dma_ready && len >= mtd->oobsize)
+ if (atmel_nand_dma_op(mtd, (void *)buf, len, 0) == 0)
+ return;
+
+ if (host->board->bus_width_16)
+ atmel_write_buf16(mtd, buf, len);
+ else
+ atmel_write_buf8(mtd, buf, len);
+}
+
/*
* Calculate HW ECC
*
@@ -398,6 +528,8 @@ static int __init atmel_nand_probe(struct platform_device *pdev)
return -ENOMEM;
}

+ host->io_phys = (dma_addr_t)mem->start;
+
host->io_base = ioremap(mem->start, mem->end - mem->start + 1);
if (host->io_base == NULL) {
printk(KERN_ERR "atmel_nand: ioremap failed\n");
@@ -516,6 +648,24 @@ static int __init atmel_nand_probe(struct platform_device *pdev)
}
}

+ if (cpu_has_dma() && use_dma) {
+ dma_cap_mask_t mask;
+
+ dma_cap_zero(mask);
+ dma_cap_set(DMA_MEMCPY, mask);
+ host->dma_chan = dma_request_channel(mask, 0, NULL);
+
+ if (!host->dma_chan) {
+ dev_err(host->dev, "Failed to request DMA channel\n");
+ host->dma_ready = 0;
+ } else
+ host->dma_ready = 1;
+ }
+ if (host->dma_ready)
+ dev_info(host->dev, "Using DMA for NAND access.\n");
+ else
+ dev_info(host->dev, "No DMA support for NAND access.\n");
+
/* second phase scan */
if (nand_scan_tail(mtd)) {
res = -ENXIO;
@@ -555,6 +705,8 @@ err_scan_ident:
err_no_card:
atmel_nand_disable(host);
platform_set_drvdata(pdev, NULL);
+ if (host->dma_chan)
+ dma_release_channel(host->dma_chan);
if (host->ecc)
iounmap(host->ecc);
err_ecc_ioremap:
@@ -578,6 +730,10 @@ static int __exit atmel_nand_remove(struct platform_device *pdev)

if (host->ecc)
iounmap(host->ecc);
+
+ if (host->dma_chan)
+ dma_release_channel(host->dma_chan);
+
iounmap(host->io_base);
kfree(host);

--
1.7.3.3


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