spi: wpcm-fiu: Add direct map support

Besides software controlled SPI transfers (UMA, "user mode access"), FIU
also supports a 16 MiB mapping window per attached flash chip.

This patch implements direct mapped read access, to speed up flash reads.

Without direct mapping:

	# time dd if=/dev/mtd0ro of=dump bs=1M
	16+0 records in
	16+0 records out
	real    1m 47.74s
	user    0m 0.00s
	sys     1m 47.75s

With direct mapping:

	# time dd if=/dev/mtd0ro of=dump bs=1M
	16+0 records in
	16+0 records out
	real    0m 30.81s
	user    0m 0.00s
	sys     0m 30.81s

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Link: https://lore.kernel.org/r/20221124191400.287918-4-j.neuschaefer@gmx.net
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-wpcm-fiu.c b/drivers/spi/spi-wpcm-fiu.c
index e525fe074f88371ff70483b8cc3ced9a2002d9f8..ab33710d50ac8b7791f1aca14e4165f5f3479475 100644 (file)
--- a/drivers/spi/spi-wpcm-fiu.c
+++ b/drivers/spi/spi-wpcm-fiu.c
@@ -51,10 +51,16 @@
  */
 #define UMA_WAIT_ITERATIONS 100
 
+/* The memory-mapped view of flash is 16 MiB long */
+#define MAX_MEMORY_SIZE_PER_CS (16 << 20)
+#define MAX_MEMORY_SIZE_TOTAL  (4 * MAX_MEMORY_SIZE_PER_CS)
+
 struct wpcm_fiu_spi {
        struct device *dev;
        struct clk *clk;
        void __iomem *regs;
+       void __iomem *memory;
+       size_t memory_size;
        struct regmap *shm_regmap;
 };
 
@@ -367,14 +373,64 @@ static int wpcm_fiu_adjust_op_size(struct spi_mem *mem, struct spi_mem_op *op)
        return 0;
 }
 
+static int wpcm_fiu_dirmap_create(struct spi_mem_dirmap_desc *desc)
+{
+       struct wpcm_fiu_spi *fiu = spi_controller_get_devdata(desc->mem->spi->controller);
+       int cs = desc->mem->spi->chip_select;
+
+       if (desc->info.op_tmpl.data.dir != SPI_MEM_DATA_IN)
+               return -ENOTSUPP;
+
+       /*
+        * Unfortunately, FIU only supports a 16 MiB direct mapping window (per
+        * attached flash chip), but the SPI MEM core doesn't support partial
+        * direct mappings. This means that we can't support direct mapping on
+        * flashes that are bigger than 16 MiB.
+        */
+       if (desc->info.offset + desc->info.length > MAX_MEMORY_SIZE_PER_CS)
+               return -ENOTSUPP;
+
+       /* Don't read past the memory window */
+       if (cs * MAX_MEMORY_SIZE_PER_CS + desc->info.offset + desc->info.length > fiu->memory_size)
+               return -ENOTSUPP;
+
+       return 0;
+}
+
+static ssize_t wpcm_fiu_direct_read(struct spi_mem_dirmap_desc *desc, u64 offs, size_t len, void *buf)
+{
+       struct wpcm_fiu_spi *fiu = spi_controller_get_devdata(desc->mem->spi->controller);
+       int cs = desc->mem->spi->chip_select;
+
+       if (offs >= MAX_MEMORY_SIZE_PER_CS)
+               return -ENOTSUPP;
+
+       offs += cs * MAX_MEMORY_SIZE_PER_CS;
+
+       if (!fiu->memory || offs >= fiu->memory_size)
+               return -ENOTSUPP;
+
+       len = min_t(size_t, len, fiu->memory_size - offs);
+       memcpy_fromio(buf, fiu->memory + offs, len);
+
+       return len;
+}
+
 static const struct spi_controller_mem_ops wpcm_fiu_mem_ops = {
        .adjust_op_size = wpcm_fiu_adjust_op_size,
        .supports_op = wpcm_fiu_supports_op,
        .exec_op = wpcm_fiu_exec_op,
+       .dirmap_create = wpcm_fiu_dirmap_create,
+       .dirmap_read = wpcm_fiu_direct_read,
 };
 
 static void wpcm_fiu_hw_init(struct wpcm_fiu_spi *fiu)
 {
+       /* Configure memory-mapped flash access */
+       writeb(FIU_BURST_CFG_R16, fiu->regs + FIU_BURST_BFG);
+       writeb(MAX_MEMORY_SIZE_TOTAL / (512 << 10), fiu->regs + FIU_CFG);
+       writeb(MAX_MEMORY_SIZE_PER_CS / (512 << 10) | BIT(6), fiu->regs + FIU_SPI_FL_CFG);
+
        /* Deassert all manually asserted chip selects */
        writeb(0x0f, fiu->regs + FIU_UMA_ECTS);
 }
@@ -404,6 +460,14 @@ static int wpcm_fiu_probe(struct platform_device *pdev)
        if (IS_ERR(fiu->clk))
                return PTR_ERR(fiu->clk);
 
+       res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "memory");
+       fiu->memory = devm_ioremap_resource(dev, res);
+       fiu->memory_size = min_t(size_t, resource_size(res), MAX_MEMORY_SIZE_TOTAL);
+       if (IS_ERR(fiu->memory)) {
+               dev_err(dev, "Failed to map flash memory window\n");
+               return PTR_ERR(fiu->memory);
+       }
+
        fiu->shm_regmap = syscon_regmap_lookup_by_phandle_optional(dev->of_node, "nuvoton,shm");
 
        wpcm_fiu_hw_init(fiu);