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

[Chuanhong Guo]

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@xxxxxxxxx>
---
 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;
+	}
+
 	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);
+	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);
-- 
2.21.0