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SubjectRe: [RFC PATCH 1/6] spi: spi-mem: Tell controller when device is ready for calibration
Hi Pratyush,

Am 2021-03-11 20:12, schrieb Pratyush Yadav:
> Some controllers like the Cadence OSPI controller need to perform a
> calibration sequence to operate at high clock speeds. This calibration
> should happen after the flash is fully initialized otherwise the
> calibration might happen in a different SPI mode from the one the flash
> is finally set to. Add a hook that can be used to tell the controller
> when the flash is ready for calibration. Whether calibration is needed
> depends on the controller.
>
> Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
> ---
> drivers/spi/spi-mem.c | 12 ++++++++++++
> include/linux/spi/spi-mem.h | 8 ++++++++
> 2 files changed, 20 insertions(+)
>
> diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
> index dc713b0c3c4d..e2f05ad3f4dc 100644
> --- a/drivers/spi/spi-mem.c
> +++ b/drivers/spi/spi-mem.c
> @@ -464,6 +464,18 @@ int spi_mem_adjust_op_size(struct spi_mem *mem,
> struct spi_mem_op *op)
> }
> EXPORT_SYMBOL_GPL(spi_mem_adjust_op_size);
>
> +int spi_mem_do_calibration(struct spi_mem *mem, struct spi_mem_op *op)
> +{
> + struct spi_controller *ctlr = mem->spi->controller;
> +
> + if (!ctlr->mem_ops || !ctlr->mem_ops->do_calibration)
> + return -EOPNOTSUPP;
> +
> + ctlr->mem_ops->do_calibration(mem, op);

Can't a calibration fail?

> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(spi_mem_do_calibration);
> +
> static ssize_t spi_mem_no_dirmap_read(struct spi_mem_dirmap_desc
> *desc,
> u64 offs, size_t len, void *buf)
> {
> diff --git a/include/linux/spi/spi-mem.h b/include/linux/spi/spi-mem.h
> index 2b65c9edc34e..97a2d280f2d0 100644
> --- a/include/linux/spi/spi-mem.h
> +++ b/include/linux/spi/spi-mem.h
> @@ -250,6 +250,12 @@ static inline void *spi_mem_get_drvdata(struct
> spi_mem *mem)
> * the currently mapped area), and the caller of
> * spi_mem_dirmap_write() is responsible for calling it again in
> * this case.
> + * @do_calibration: perform calibration needed for high SPI clock
> speed
> + * operation. Should be called after the SPI memory device has
> + * been completely initialized. The op passed should contain
> + * a template for the read operation used for the device so
> + * the controller can decide what type of calibration is
> + * required for this type of read.
> *
> * This interface should be implemented by SPI controllers providing
> an
> * high-level interface to execute SPI memory operation, which is
> usually the
> @@ -274,6 +280,7 @@ struct spi_controller_mem_ops {
> u64 offs, size_t len, void *buf);
> ssize_t (*dirmap_write)(struct spi_mem_dirmap_desc *desc,
> u64 offs, size_t len, const void *buf);
> + void (*do_calibration)(struct spi_mem *mem, struct spi_mem_op *op);
> };
>
> /**
> @@ -346,6 +353,7 @@ bool spi_mem_dtr_supports_op(struct spi_mem *mem,
> #endif /* CONFIG_SPI_MEM */
>
> int spi_mem_adjust_op_size(struct spi_mem *mem, struct spi_mem_op
> *op);
> +int spi_mem_do_calibration(struct spi_mem *mem, struct spi_mem_op
> *op);
>
> bool spi_mem_supports_op(struct spi_mem *mem,
> const struct spi_mem_op *op);

--
-michael

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