mtd: spi-nor: fsl-quadspi: dynamically map memory space for AHB read

QSPI may failed to map enough memory (256MB) for AHB read in
previous implementation, especially in 3G/1G memory layout kernel.
Dynamically map memory to avoid such issue.

This implementation generally map QUADSPI_MAX_IOMAP (default 4MB) memory
for AHB read, it should be enough for common scenarios, and the side
effect (0.6% performance drop) is minor.

Previous implementation

root@imx6qdlsolo:~# dd if=/dev/mtd0 of=/dev/null bs=1K count=32K
32768+0 records in
32768+0 records out
33554432 bytes (34 MB) copied, 2.16006 s, 15.5 MB/s

root@imx6qdlsolo:~# dd if=/dev/mtd0 of=/dev/null bs=32M count=1
1+0 records in
1+0 records out
33554432 bytes (34 MB) copied, 1.43149 s, 23.4 MB/s

After applied the patch

root@imx6qdlsolo:~# dd if=/dev/mtd0 of=/dev/null bs=1K count=32K
32768+0 records in
32768+0 records out
33554432 bytes (34 MB) copied, 2.1743 s, 15.4 MB/s

root@imx6qdlsolo:~# dd if=/dev/mtd0 of=/dev/null bs=32M count=1
1+0 records in
1+0 records out
33554432 bytes (34 MB) copied, 1.43158 s, 23.4 MB/s

Signed-off-by: Han Xu <han.xu@freescale.com>
Signed-off-by: Frank Li <Frank.Li@freescale.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

diff --git a/drivers/mtd/spi-nor/fsl-quadspi.c b/drivers/mtd/spi-nor/fsl-quadspi.c
index 1946c6d..2d46036 100644 (file)
--- a/drivers/mtd/spi-nor/fsl-quadspi.c
+++ b/drivers/mtd/spi-nor/fsl-quadspi.c
@@ -192,6 +192,8 @@
 #define SEQID_EN4B             10
 #define SEQID_BRWR             11
 
+#define QUADSPI_MIN_IOMAP SZ_4M
+
 enum fsl_qspi_devtype {
        FSL_QUADSPI_VYBRID,
        FSL_QUADSPI_IMX6SX,
@@ -223,8 +225,10 @@ struct fsl_qspi {
        struct mtd_info mtd[FSL_QSPI_MAX_CHIP];
        struct spi_nor nor[FSL_QSPI_MAX_CHIP];
        void __iomem *iobase;
-       void __iomem *ahb_base; /* Used when read from AHB bus */
+       void __iomem *ahb_addr;
        u32 memmap_phy;
+       u32 memmap_offs;
+       u32 memmap_len;
        struct clk *clk, *clk_en;
        struct device *dev;
        struct completion c;
@@ -732,11 +736,42 @@ static int fsl_qspi_read(struct spi_nor *nor, loff_t from,
        struct fsl_qspi *q = nor->priv;
        u8 cmd = nor->read_opcode;
 
-       dev_dbg(q->dev, "cmd [%x],read from (0x%p, 0x%.8x, 0x%.8x),len:%d\n",
-               cmd, q->ahb_base, q->chip_base_addr, (unsigned int)from, len);
+       /* if necessary,ioremap buffer before AHB read, */
+       if (!q->ahb_addr) {
+               q->memmap_offs = q->chip_base_addr + from;
+               q->memmap_len = len > QUADSPI_MIN_IOMAP ? len : QUADSPI_MIN_IOMAP;
+
+               q->ahb_addr = ioremap_nocache(
+                               q->memmap_phy + q->memmap_offs,
+                               q->memmap_len);
+               if (!q->ahb_addr) {
+                       dev_err(q->dev, "ioremap failed\n");
+                       return -ENOMEM;
+               }
+       /* ioremap if the data requested is out of range */
+       } else if (q->chip_base_addr + from < q->memmap_offs
+                       || q->chip_base_addr + from + len >
+                       q->memmap_offs + q->memmap_len) {
+               iounmap(q->ahb_addr);
+
+               q->memmap_offs = q->chip_base_addr + from;
+               q->memmap_len = len > QUADSPI_MIN_IOMAP ? len : QUADSPI_MIN_IOMAP;
+               q->ahb_addr = ioremap_nocache(
+                               q->memmap_phy + q->memmap_offs,
+                               q->memmap_len);
+               if (!q->ahb_addr) {
+                       dev_err(q->dev, "ioremap failed\n");
+                       return -ENOMEM;
+               }
+       }
+
+       dev_dbg(q->dev, "cmd [%x],read from 0x%p, len:%d\n",
+               cmd, q->ahb_addr + q->chip_base_addr + from - q->memmap_offs,
+               len);
 
        /* Read out the data directly from the AHB buffer.*/
-       memcpy(buf, q->ahb_base + q->chip_base_addr + from, len);
+       memcpy(buf, q->ahb_addr + q->chip_base_addr + from - q->memmap_offs,
+               len);
 
        *retlen += len;
        return 0;
@@ -821,9 +856,11 @@ static int fsl_qspi_probe(struct platform_device *pdev)
 
        res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
                                        "QuadSPI-memory");
-       q->ahb_base = devm_ioremap_resource(dev, res);
-       if (IS_ERR(q->ahb_base))
-               return PTR_ERR(q->ahb_base);
+       if (!devm_request_mem_region(dev, res->start, resource_size(res),
+                                    res->name)) {
+               dev_err(dev, "can't request region for resource %pR\n", res);
+               return -EBUSY;
+       }
 
        q->memmap_phy = res->start;
 
@@ -989,6 +1026,10 @@ static int fsl_qspi_remove(struct platform_device *pdev)
        mutex_destroy(&q->lock);
        clk_unprepare(q->clk);
        clk_unprepare(q->clk_en);
+
+       if (q->ahb_addr)
+               iounmap(q->ahb_addr);
+
        return 0;
 }