[PATCH v2 3/3] spi: wpcm-fiu: Add direct map support

Jonathan Neuschäfer
2022-11-24T19:14:30Z

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>
---

v2:
- Fix a few nits from the kernel test robot
- Fix check for fiu->memory mapping error

v1:
- https://lore.kernel.org/lkml/20221105185911.1547847-9-j.neuschaefer@gmx.net/
---
drivers/spi/spi-wpcm-fiu.c | 64 ++++++++++++++++++++++++++++++++++++++
1 file changed, 64 insertions(+)

diff --git a/drivers/spi/spi-wpcm-fiu.c b/drivers/spi/spi-wpcm-fiu.c
index e525fe074f883..ab33710d50ac8 100644
--- 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);
--
2.35.1