Re: [PATCH 1/2] mtd: mtk-quadspi: add support for memory-mapped flash reading

Vignesh Raghavendra
2019-11-07T06:06:00Z

Hi,

On 06/11/19 7:37 PM, Chuanhong Guo wrote:
> PIO reading mode on this controller is ridiculously inefficient
> (one cmd+addr+dummy sequence reads only one byte)
> This patch adds support for reading from memory-mapped flash area
> which increases reading speed from 1MB/s to 5.6MB/s
>
> Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
> ---
> drivers/mtd/spi-nor/mtk-quadspi.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/drivers/mtd/spi-nor/mtk-quadspi.c b/drivers/mtd/spi-nor/mtk-quadspi.c
> index 34db01ab6cab..ba8b3be39896 100644
> --- a/drivers/mtd/spi-nor/mtk-quadspi.c
> +++ b/drivers/mtd/spi-nor/mtk-quadspi.c
> @@ -106,6 +106,7 @@ struct mtk_nor {
> struct spi_nor nor;
> struct device *dev;
> void __iomem *base; /* nor flash base address */
> + void __iomem *flash_base;
> struct clk *spi_clk;
> struct clk *nor_clk;
> };
> @@ -272,6 +273,11 @@ static ssize_t mtk_nor_read(struct spi_nor *nor, loff_t from, size_t length,
> mtk_nor_set_read_mode(mtk_nor);
> mtk_nor_set_addr(mtk_nor, addr);
>
> + if (mtk_nor->flash_base) {
> + memcpy_fromio(buffer, mtk_nor->flash_base + from, length);
> + return length;
> + }
> +

Don't you need to check if access is still within valid memory mapped
window?

> for (i = 0; i < length; i++) {
> ret = mtk_nor_execute_cmd(mtk_nor, MTK_NOR_PIO_READ_CMD);
> if (ret < 0)
> @@ -475,6 +481,11 @@ static int mtk_nor_drv_probe(struct platform_device *pdev)
> if (IS_ERR(mtk_nor->base))
> return PTR_ERR(mtk_nor->base);
>
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> + mtk_nor->flash_base = devm_ioremap_resource(&pdev->dev, res);

There is a single API now: devm_platform_ioremap_resource().

> + if (IS_ERR(mtk_nor->flash_base))
> + mtk_nor->flash_base = NULL;
> +
> mtk_nor->spi_clk = devm_clk_get(&pdev->dev, "spi");
> if (IS_ERR(mtk_nor->spi_clk))
> return PTR_ERR(mtk_nor->spi_clk);
>

--
Regards
Vignesh