Re: [PATCH v7 1/4] mtd: spi-nor: introduce SPI 1-2-2 and SPI 1-4-4 protocols

From: Marek Vasut
Date: Tue Apr 18 2017 - 19:07:45 EST


On 04/19/2017 12:51 AM, Cyrille Pitchen wrote:
> This patch changes the prototype of spi_nor_scan(): its 3rd parameter
> is replaced by a 'struct spi_nor_hwcaps' pointer, which tells the spi-nor
> framework about the actual hardware capabilities supported by the SPI
> controller and its driver.
>
> Besides, this patch also introduces a new 'struct spi_nor_flash_parameter'
> telling the spi-nor framework about the hardware capabilities supported by
> the SPI flash memory and the associated settings required to use those
> hardware caps.
>
> Then, to improve the readability of spi_nor_scan(), the discovery of the
> memory settings and the memory initialization are now split into two
> dedicated functions.
>
> 1 - spi_nor_init_params()
>
> The spi_nor_init_params() function is responsible for initializing the
> 'struct spi_nor_flash_parameter'. Currently this structure is filled with
> legacy values but further patches will allow to override some parameter
> values dynamically, for instance by reading the JESD216 Serial Flash
> Discoverable Parameter (SFDP) tables from the SPI memory.
> The spi_nor_init_params() function only deals with the hardware
> capabilities of the SPI flash memory: especially it doesn't care about
> the hardware capabilities supported by the SPI controller.
>
> 2 - spi_nor_setup()
>
> The second function is called once the 'struct spi_nor_flash_parameter'
> has been initialized by spi_nor_init_params().
> With both 'struct spi_nor_flash_parameter' and 'struct spi_nor_hwcaps',
> the new argument of spi_nor_scan(), spi_nor_setup() computes the best
> match between hardware caps supported by both the (Q)SPI memory and
> controller hence selecting the relevant settings for (Fast) Read and Page
> Program operations.
>
> Signed-off-by: Cyrille Pitchen <cyrille.pitchen@xxxxxxxxx>

[...]

> --- a/include/linux/mtd/spi-nor.h
> +++ b/include/linux/mtd/spi-nor.h
> @@ -119,13 +119,57 @@
> /* Configuration Register bits. */
> #define CR_QUAD_EN_SPAN BIT(1) /* Spansion Quad I/O */
>
> -enum read_mode {
> - SPI_NOR_NORMAL = 0,
> - SPI_NOR_FAST,
> - SPI_NOR_DUAL,
> - SPI_NOR_QUAD,
> +/* Supported SPI protocols */
> +#define SNOR_PROTO_INST_MASK GENMASK(23, 16)
> +#define SNOR_PROTO_INST_SHIFT 16
> +#define SNOR_PROTO_INST(_nbits) \
> + ((((u32)(_nbits)) << SNOR_PROTO_INST_SHIFT) & SNOR_PROTO_INST_MASK)

Is the u32 cast needed ?

> +#define SNOR_PROTO_ADDR_MASK GENMASK(15, 8)
> +#define SNOR_PROTO_ADDR_SHIFT 8
> +#define SNOR_PROTO_ADDR(_nbits) \
> + ((((u32)(_nbits)) << SNOR_PROTO_ADDR_SHIFT) & SNOR_PROTO_ADDR_MASK)
> +
> +#define SNOR_PROTO_DATA_MASK GENMASK(7, 0)
> +#define SNOR_PROTO_DATA_SHIFT 0
> +#define SNOR_PROTO_DATA(_nbits) \
> + ((((u32)(_nbits)) << SNOR_PROTO_DATA_SHIFT) & SNOR_PROTO_DATA_MASK)

[...]

> +static inline u8 spi_nor_get_protocol_inst_nbits(enum spi_nor_protocol proto)
> +{
> + return ((u32)(proto & SNOR_PROTO_INST_MASK)) >> SNOR_PROTO_INST_SHIFT;

DTTO, is the cast needed ?

> +}
> +
> +static inline u8 spi_nor_get_protocol_addr_nbits(enum spi_nor_protocol proto)
> +{
> + return ((u32)(proto & SNOR_PROTO_ADDR_MASK)) >> SNOR_PROTO_ADDR_SHIFT;
> +}
> +
> +static inline u8 spi_nor_get_protocol_data_nbits(enum spi_nor_protocol proto)
> +{
> + return ((u32)(proto & SNOR_PROTO_DATA_MASK)) >> SNOR_PROTO_DATA_SHIFT;
> +}
> +
> +static inline u8 spi_nor_get_protocol_width(enum spi_nor_protocol proto)
> +{
> + return spi_nor_get_protocol_data_nbits(proto);
> +}

[...]

Looks good otherwise.

--
Best regards,
Marek Vasut