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Date:   Tue, 10 Jan 2023 14:40:30 +0300
From:   Serge Semin <fancer.lancer@gmail.com>
To:     Sudip Mukherjee <sudip.mukherjee@sifive.com>
Cc:     Mark Brown <broonie@kernel.org>, Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        jude.onyenegecha@sifive.com, ben.dooks@sifive.com,
        jeegar.lakhani@sifive.com, linux-spi@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 06/15] spi: dw: Introduce dual/quad/octal spi
Message-ID: <20230110114030.hz3hkou5owxaeopc@mobilestation>
References: <20221212180732.79167-1-sudip.mukherjee@sifive.com>
 <20221212180732.79167-7-sudip.mukherjee@sifive.com>
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On Mon, Dec 12, 2022 at 06:07:23PM +0000, Sudip Mukherjee wrote:
> If the spi transfer is using dual/quad/octal spi mode, then we need to
> update the SPI_CTRLR0 register. The SPI_CTRLR0 register will be updated
> in dw_spi_update_config() via the values in dw_spi_cfg.
> 
> Signed-off-by: Sudip Mukherjee <sudip.mukherjee@sifive.com>
> ---
> 
> Note: DW_SPI_SPI_CTRLR0_INST_L_INST_L16 will not work yet as
> spi_mem_default_supports_op() checks for op->cmd.nbytes != 1.
> 
>  drivers/spi/spi-dw-core.c | 46 +++++++++++++++++++++++++++++++++++++++
>  drivers/spi/spi-dw.h      |  9 ++++++++
>  2 files changed, 55 insertions(+)
> 
> diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c
> index 89438ae2df17d..06169aa3f37bf 100644
> --- a/drivers/spi/spi-dw-core.c
> +++ b/drivers/spi/spi-dw-core.c
> @@ -836,10 +836,56 @@ static int dw_spi_exec_enh_mem_op(struct spi_mem *mem, const struct spi_mem_op *
>  {
>  	struct spi_controller *ctlr = mem->spi->controller;
>  	struct dw_spi *dws = spi_controller_get_devdata(ctlr);
> +	struct dw_spi_cfg cfg;
> +

> +	switch (op->data.buswidth) {
> +	case 2:
> +		cfg.spi_frf = DW_SPI_CTRLR0_SPI_FRF_DUAL_SPI;
> +		break;
> +	case 4:
> +		cfg.spi_frf = DW_SPI_CTRLR0_SPI_FRF_QUAD_SPI;
> +		break;
> +	case 8:
> +		cfg.spi_frf = DW_SPI_CTRLR0_SPI_FRF_OCT_SPI;
> +		break;
> +	default:
> +		return dw_spi_exec_mem_op(mem, op);

case 1:
	return dw_spi_exec_mem_op(mem, op);
case 2:
	cfg.enh_frf = DW_SPI_CTRLR0_SPI_FRF_DUAL_SPI;
	break;
...
default:
	return -EINVAL;

> +	}
>  
>  	/* Collect cmd and addr into a single buffer */
>  	dw_spi_init_enh_mem_buf(dws, op);
>  
> +	cfg.dfs = 8;
> +	cfg.freq = clamp(mem->spi->max_speed_hz, 0U, dws->max_mem_freq);
> +	cfg.ndf = op->data.nbytes;
> +	if (op->data.dir == SPI_MEM_DATA_IN)
> +		cfg.tmode = DW_SPI_CTRLR0_TMOD_RO;
> +	else
> +		cfg.tmode = DW_SPI_CTRLR0_TMOD_TO;

Newline, please.

> +	if (op->data.buswidth == op->addr.buswidth &&
> +	    op->data.buswidth == op->cmd.buswidth)
> +		cfg.trans_t = DW_SPI_SPI_CTRLR0_TRANS_TYPE_TT2;
> +	else if (op->data.buswidth == op->addr.buswidth)
> +		cfg.trans_t = DW_SPI_SPI_CTRLR0_TRANS_TYPE_TT1;
> +	else
> +		cfg.trans_t = DW_SPI_SPI_CTRLR0_TRANS_TYPE_TT0;
> +

> +	cfg.addr_l = clamp(op->addr.nbytes * 2, 0, 0xf);

First the address length should be checked in the
spi_controller_mem_ops.supports_op method. Thus the clamping procedure
would be redundant. Second instead of using the multiplication
operator I would suggest to have the bitwise left-shift op utilized
here, (cfg.addr_l = op->addr.nbytes << 2). This shall look a bit more
coherent.


> +	if (op->cmd.nbytes > 1)
> +		cfg.inst_l = DW_SPI_SPI_CTRLR0_INST_L_INST_L16;

No. Firstly INST_L16 means 2-bytes length. Using greater-than op here
is incorrect. Secondly the command part length should be
checked in the spi_controller_mem_ops.supports_op callback.

> +	else if (op->cmd.nbytes == 1)
> +		cfg.inst_l = DW_SPI_SPI_CTRLR0_INST_L_INST_L8;
> +	else
> +		cfg.inst_l = DW_SPI_SPI_CTRLR0_INST_L_INST_L0;
> +

> +	cfg.wait_c = (op->dummy.nbytes * (BITS_PER_BYTE / op->dummy.buswidth));

Hm, what if buswidth is zero?

> +
> +	dw_spi_enable_chip(dws, 0);
> +
> +	dw_spi_update_config(dws, mem->spi, &cfg);
> +
> +	dw_spi_enable_chip(dws, 1);
> +
>  	return 0;
>  }
>  
> diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
> index 327d037bdb10e..494b830ad1026 100644
> --- a/drivers/spi/spi-dw.h
> +++ b/drivers/spi/spi-dw.h
> @@ -101,6 +101,9 @@
>  #define DW_HSSI_CTRLR0_SPI_FRF_MASK		GENMASK(23, 22)
>  #define DW_PSSI_CTRLR0_SPI_FRF_MASK		GENMASK(22, 21)

>  #define DW_SPI_CTRLR0_SPI_FRF_STD_SPI		0x0
> +#define DW_SPI_CTRLR0_SPI_FRF_DUAL_SPI		0x1
> +#define DW_SPI_CTRLR0_SPI_FRF_QUAD_SPI		0x2
> +#define DW_SPI_CTRLR0_SPI_FRF_OCT_SPI		0x3

Please replace SPI_FRF with ENH_FRF and drop _SPI suffix from the
macros.

>  
>  /* Bit fields in CTRLR1 */
>  #define DW_SPI_NDF_MASK				GENMASK(15, 0)
> @@ -132,7 +135,13 @@
>  #define DW_SPI_SPI_CTRLR0_CLK_STRETCH_EN	BIT(30)
>  #define DW_SPI_SPI_CTRLR0_WAIT_CYCLE_MASK	GENMASK(15, 11)
>  #define DW_SPI_SPI_CTRLR0_INST_L_MASK		GENMASK(9, 8)

> +#define DW_SPI_SPI_CTRLR0_INST_L_INST_L0	0x0
> +#define DW_SPI_SPI_CTRLR0_INST_L_INST_L8	0x2
> +#define DW_SPI_SPI_CTRLR0_INST_L_INST_L16	0x3
>  #define DW_SPI_SPI_CTRLR0_ADDR_L_MASK		GENMASK(5, 2)
> +#define DW_SPI_SPI_CTRLR0_TRANS_TYPE_TT0	0x0
> +#define DW_SPI_SPI_CTRLR0_TRANS_TYPE_TT1	0x1
> +#define DW_SPI_SPI_CTRLR0_TRANS_TYPE_TT2	0x2

Please replace SPI_CTRLR0 with ENH_CTRLR0.

-Serge(y)

>  
>  /* Mem/DMA operations helpers */
>  #define DW_SPI_WAIT_RETRIES			5
> -- 
> 2.30.2
>