[PATCH] spi: ath79: add mem_ops for fast-read

[PATCH] spi: ath79: add mem_ops for fast-read

[Luiz Angelo Daros de Luca]

Reading from memory is 3x faster than bit-bang read operation. Also,
for tl-wr2543nd, the bit-bang read was sporadically returning random
data, possibly a HW defect, while fast-read works as expected.

Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>
---
 drivers/spi/spi-ath79.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/drivers/spi/spi-ath79.c b/drivers/spi/spi-ath79.c
index d1e287d2d9cd..607e7a49fb89 100644
--- a/drivers/spi/spi-ath79.c
+++ b/drivers/spi/spi-ath79.c
@@ -15,6 +15,7 @@
 #include <linux/platform_device.h>
 #include <linux/io.h>
 #include <linux/spi/spi.h>
+#include <linux/spi/spi-mem.h>
 #include <linux/spi/spi_bitbang.h>
 #include <linux/bitops.h>
 #include <linux/clk.h>
@@ -133,6 +134,38 @@ static u32 ath79_spi_txrx_mode0(struct spi_device *spi, unsigned int nsecs,
 	return ath79_spi_rr(sp, AR71XX_SPI_REG_RDS);
 }
 
+static int ath79_exec_mem_op(struct spi_mem *mem,
+			     const struct spi_mem_op *op)
+{
+	struct ath79_spi *sp = ath79_spidev_to_sp(mem->spi);
+
+	/* Ensures that reading is performed on device connected to hardware cs0 */
+	if (mem->spi->chip_select || mem->spi->cs_gpiod)
+		return -ENOTSUPP;
+
+	/* Only use for fast-read op. */
+	if (op->cmd.opcode != 0x0b || op->data.dir != SPI_MEM_DATA_IN ||
+	    op->addr.nbytes != 3 || op->dummy.nbytes != 1)
+		return -ENOTSUPP;
+
+	/* disable GPIO mode */
+	ath79_spi_wr(sp, AR71XX_SPI_REG_FS, 0);
+
+	memcpy_fromio(op->data.buf.in, sp->base + op->addr.val, op->data.nbytes);
+
+	/* enable GPIO mode */
+	ath79_spi_wr(sp, AR71XX_SPI_REG_FS, AR71XX_SPI_FS_GPIO);
+
+	/* restore IOC register */
+	ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base);
+
+	return 0;
+}
+
+static const struct spi_controller_mem_ops ath79_mem_ops = {
+	.exec_op = ath79_exec_mem_op,
+};
+
 static int ath79_spi_probe(struct platform_device *pdev)
 {
 	struct spi_master *master;
@@ -154,6 +187,7 @@ static int ath79_spi_probe(struct platform_device *pdev)
 	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32);
 	master->flags = SPI_MASTER_GPIO_SS;
 	master->num_chipselect = 3;
+	master->mem_ops = &ath79_mem_ops;
 
 	sp->bitbang.master = master;
 	sp->bitbang.chipselect = ath79_spi_chipselect;
-- 
2.34.1

Re: [PATCH] spi: ath79: add mem_ops for fast-read

[Mark Brown]

On Sat, 29 Jan 2022 01:04:53 -0300, Luiz Angelo Daros de Luca wrote:
> Reading from memory is 3x faster than bit-bang read operation. Also,
> for tl-wr2543nd, the bit-bang read was sporadically returning random
> data, possibly a HW defect, while fast-read works as expected.
> 
> 

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next

Thanks!

[1/1] spi: ath79: add mem_ops for fast-read
      commit: d08de0259dfe172caf073b921c6b27ff089605a9

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark