[PATCH v2 2/2] mtd: sh_flctl: Use DMA for data fifo FLTDFIFO when available

[Guennadi Liakhovetski]

On Mon, 24 Sep 2012, Bastian Hecht wrote:

> Map and unmap DMA buffers, trigger the DMA and wait for the completion.
> On failure we fallback to PIO mode.
> 
> Signed-off-by: Bastian Hecht <hechtb at gmail.com>
> ---
> log v2: dropped a forward declaration
> 
>  drivers/mtd/nand/sh_flctl.c  |   97 +++++++++++++++++++++++++++++++++++++++++-
>  include/linux/mtd/sh_flctl.h |    1 +
>  2 files changed, 96 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/nand/sh_flctl.c b/drivers/mtd/nand/sh_flctl.c
> index 9659483..0d90af8 100644
> --- a/drivers/mtd/nand/sh_flctl.c
> +++ b/drivers/mtd/nand/sh_flctl.c
> @@ -24,6 +24,8 @@
>  #include <linux/module.h>
>  #include <linux/kernel.h>
>  #include <linux/delay.h>
> +#include <linux/dmaengine.h>
> +#include <linux/dma-mapping.h>

As I suggested in my comments to patch 1/2, I would merge these patches. 
In any case the headers are needed already in the first patch, including 
sh_dma.h.

Thanks
Guennadi


>  #include <linux/interrupt.h>
>  #include <linux/io.h>
>  #include <linux/platform_device.h>
> @@ -106,6 +108,13 @@ static void wait_completion(struct sh_flctl *flctl)
>  	writeb(0x0, FLTRCR(flctl));
>  }
>  
> +static void flctl_dma_complete(void *param)
> +{
> +	struct sh_flctl *flctl = param;
> +
> +	complete(&flctl->dma_complete);
> +}
> +
>  static void flctl_release_dma(struct sh_flctl *flctl)
>  {
>  	if (flctl->chan_fifo0_rx) {
> @@ -331,6 +340,69 @@ static void wait_wecfifo_ready(struct sh_flctl *flctl)
>  	timeout_error(flctl, __func__);
>  }
>  
> +static void flctl_dma_fifo0_transfer(struct sh_flctl *flctl, unsigned long *buf,
> +					int len, enum dma_data_direction dir)
> +{
> +	struct dma_async_tx_descriptor *desc = NULL;
> +	struct dma_chan *chan;
> +	enum dma_transfer_direction tr_dir;
> +	dma_addr_t dma_addr;
> +	dma_cookie_t cookie = -EINVAL;
> +	uint32_t reg;
> +	int ret;
> +
> +	if (dir == DMA_FROM_DEVICE) {
> +		chan = flctl->chan_fifo0_rx;
> +		tr_dir = DMA_DEV_TO_MEM;
> +	} else {
> +		chan = flctl->chan_fifo0_tx;
> +		tr_dir = DMA_MEM_TO_DEV;
> +	}
> +
> +	dma_addr = dma_map_single(chan->device->dev, buf, len, dir);
> +
> +	if (dma_addr)
> +		desc = dmaengine_prep_slave_single(chan, dma_addr, len,
> +			tr_dir, DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> +
> +	if (desc) {
> +		reg = readl(FLINTDMACR(flctl));
> +		reg |= DREQ0EN;
> +		writel(reg, FLINTDMACR(flctl));
> +
> +		desc->callback = flctl_dma_complete;
> +		desc->callback_param = flctl;
> +		cookie = dmaengine_submit(desc);
> +
> +		dma_async_issue_pending(chan);
> +	}
> +
> +	if (!desc) {
> +		/* DMA failed, fall back to PIO */
> +		flctl_release_dma(flctl);
> +		dev_warn(&flctl->pdev->dev,
> +			 "DMA failed, falling back to PIO\n");
> +		goto out;
> +	}
> +
> +	ret =
> +	wait_for_completion_timeout(&flctl->dma_complete,
> +				msecs_to_jiffies(3000));
> +
> +	if (ret <= 0) {
> +		chan->device->device_control(chan, DMA_TERMINATE_ALL, 0);
> +		dev_err(&flctl->pdev->dev, "wait_for_completion_timeout\n");
> +	}
> +
> +out:
> +	reg = readl(FLINTDMACR(flctl));
> +	reg &= ~DREQ0EN;
> +	writel(reg, FLINTDMACR(flctl));
> +
> +	dma_unmap_single(chan->device->dev, dma_addr, len, dir);
> +	init_completion(&flctl->dma_complete);
> +}
> +
>  static void read_datareg(struct sh_flctl *flctl, int offset)
>  {
>  	unsigned long data;
> @@ -349,6 +421,16 @@ static void read_fiforeg(struct sh_flctl *flctl, int rlen, int offset)
>  
>  	len_4align = (rlen + 3) / 4;
>  
> +	/* initiate DMA transfer */
> +	if (flctl->chan_fifo0_rx && rlen >= 32) {
> +		flctl_dma_fifo0_transfer(flctl, buf, rlen, DMA_DEV_TO_MEM);
> +		for (i = 0; i < len_4align; i++)
> +			buf[i] = be32_to_cpu(buf[i]);
> +
> +		return;
> +	}
> +
> +	/* do polling transfer */
>  	for (i = 0; i < len_4align; i++) {
>  		wait_rfifo_ready(flctl);
>  		buf[i] = readl(FLDTFIFO(flctl));
> @@ -378,13 +460,24 @@ static enum flctl_ecc_res_t read_ecfiforeg
>  static void write_fiforeg(struct sh_flctl *flctl, int rlen, int offset)
>  {
>  	int i, len_4align;
> -	unsigned long *data = (unsigned long *)&flctl->done_buff[offset];
> +	unsigned long *buf = (unsigned long *)&flctl->done_buff[offset];
>  	void *fifo_addr = (void *)FLDTFIFO(flctl);
>  
>  	len_4align = (rlen + 3) / 4;
> +
> +	/* initiate DMA transfer */
> +	if (flctl->chan_fifo0_tx && rlen >= 32) {
> +		for (i = 0; i < len_4align; i++)
> +			buf[i] = cpu_to_be32(buf[i]);
> +
> +		flctl_dma_fifo0_transfer(flctl, buf, rlen, DMA_MEM_TO_DEV);
> +		return;
> +	}
> +
> +	/* do polling transfer */
>  	for (i = 0; i < len_4align; i++) {
>  		wait_wfifo_ready(flctl);
> -		writel(cpu_to_be32(data[i]), fifo_addr);
> +		writel(cpu_to_be32(buf[i]), fifo_addr);
>  	}
>  }
>  
> diff --git a/include/linux/mtd/sh_flctl.h b/include/linux/mtd/sh_flctl.h
> index 20d3f48..d55ec25 100644
> --- a/include/linux/mtd/sh_flctl.h
> +++ b/include/linux/mtd/sh_flctl.h
> @@ -109,6 +109,7 @@
>  #define ESTERINTE	(0x1 << 24)	/* ECC error interrupt enable */
>  #define AC1CLR		(0x1 << 19)	/* ECC FIFO clear */
>  #define AC0CLR		(0x1 << 18)	/* Data FIFO clear */
> +#define DREQ0EN		(0x1 << 16)	/* FLDTFIFODMA Request Enable */
>  #define ECERB		(0x1 << 9)	/* ECC error */
>  #define STERB		(0x1 << 8)	/* Status error */
>  #define STERINTE	(0x1 << 4)	/* Status error enable */
> -- 
> 1.7.5.4
> 

---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/