linux-kernel - Re: [PATCH 05/11] spi: dw: define SPI

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Date:   Sat, 27 Aug 2022 01:19:23 +0300
From:   Serge Semin <fancer.lancer@...il.com>
To:     Sudip Mukherjee <sudip.mukherjee@...ive.com>
Cc:     Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        Mark Brown <broonie@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        greentime.hu@...ive.com, jude.onyenegecha@...ive.com,
        william.salmon@...ive.com, adnan.chowdhury@...ive.com,
        ben.dooks@...ive.com, linux-spi@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        jeegar.lakhani@...ive.com
Subject: Re: [PATCH 05/11] spi: dw: define SPI_CTRLR0 register and its fields

On Tue, Aug 02, 2022 at 06:57:49PM +0100, Sudip Mukherjee wrote:
> Synopsys SSI controllers supporting enhanced SPI mode of operation has
> SPI Control Register at offset 0xf4 which controls the following:
> 
> CLK_STRETCH_EN: Enables clock stretching capability in SPI transfers.
> In case of write, if the FIFO becomes empty DWC_ssi will stretch the
> clock until FIFO has enough data to continue the transfer. In case of
> read, if the receive FIFO becomes full DWC_ssi will stop the clock until
> data has been read from the FIFO.
> 
> WAIT_CYCLES: Wait cycles in Dual/Quad/Octal mode between control frames
> transmit and data reception.
> 
> INST_L: Dual/Quad/Octal mode instruction length in bits.
> 
> ADDR_L: defines Length of Address to be transmitted.
> 
> For now, we are only using 32bit Address length and 8 bit Instruction
> length.
> 
> Signed-off-by: Sudip Mukherjee <sudip.mukherjee@...ive.com>
> ---
>  drivers/spi/spi-dw.h | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
> index b8cc20e0deaa..a7a4637d6d32 100644
> --- a/drivers/spi/spi-dw.h
> +++ b/drivers/spi/spi-dw.h
> @@ -63,6 +63,17 @@
>  #define DW_SPI_RX_SAMPLE_DLY		0xf0
>  #define DW_SPI_CS_OVERRIDE		0xf4
>  

> +/* Register offsets (Defined in DWC SSI 1.03a) */

Drop this comment. The CSR can exist in the DW APB SSI too

> +#define DW_HSSI_SPI_CTRLR0		0xf4

#define DW_SSI_SPI_CTRLR0		0xf4

> +
> +/* Bit fields in SPI_CTRLR0 (Defined in DWC SSI 1.03a) */

Drop the IP-core ID and version from the comment. As I said the eSPI
feature can be enabled for DW APB SSI too.

> +#define DW_HSSI_SPI_CTRLR0_CLK_STRETCH_EN	BIT(30)
> +#define DW_HSSI_SPI_CTRLR0_WAIT_CYCLE_MASK	GENMASK(15, 11)
> +#define DW_HSSI_SPI_CTRLR0_INST_L_MASK		GENMASK(9, 8)
> +#define DW_HSSI_SPI_CTRLR0_INST_L8		0x2
> +#define DW_HSSI_SPI_CTRLR0_ADDR_L_MASK		GENMASK(5, 2)
> +#define DW_HSSI_SPI_CTRLR0_ADDR_L32		0x8

Move this to the tail of the CSR fields macros definition (right after
the DW_SPI_DMACR_TDMAE macros) and s/HSSI/SPI .

-Sergey

> +
>  /* Bit fields in CTRLR0 (DWC APB SSI) */
>  #define DW_PSSI_CTRLR0_DFS_MASK			GENMASK(3, 0)
>  #define DW_PSSI_CTRLR0_DFS32_MASK		GENMASK(20, 16)
> -- 
> 2.30.2
>