linux-kernel - Re: [PATCH v3 4/9] iio: dac: adi-axi-dac: add bus mode setup

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Message-ID: <a8630218741ace433752e855f81664f1123d51a3.camel@gmail.com>
Date: Mon, 13 Jan 2025 16:05:26 +0000
From: Nuno Sá <noname.nuno@...il.com>
To: Angelo Dureghello <adureghello@...libre.com>, Lars-Peter Clausen
	 <lars@...afoo.de>, Michael Hennerich <Michael.Hennerich@...log.com>, 
 Jonathan Cameron
	 <jic23@...nel.org>, David Lechner <dlechner@...libre.com>, Nuno Sa
	 <nuno.sa@...log.com>
Cc: Jonathan Cameron <Jonathan.Cameron@...wei.com>,
 linux-iio@...r.kernel.org, 	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 4/9] iio: dac: adi-axi-dac: add bus mode setup

On Fri, 2025-01-10 at 11:24 +0100, Angelo Dureghello wrote:
> From: Angelo Dureghello <adureghello@...libre.com>
> 
> The ad354xr requires DSPI mode (2 data lanes) to work in buffering
> mode, so backend needs to allow a mode selection between:
>     SPI  (entire ad35xxr family),
>     DSPI (ad354xr),
>     QSPI (ad355xr).
> 

I guess this could be misleading people to think this is being handled by the
backend framework when it's not. I would rephrase things a bit in here.

> About removal of AXI_DAC_CUSTOM_CTRL_SYNCED_TRANSFER, according to
> the HDL history the flag has never been used. So looks like the driver
> was including it by mistake or in anticipation for something that was
> never implemented on HDL side.
> 
> Current HDL updated documentation confirm it is actually not in use
> anymore and replaced by the IO_MODE bits.
> 
> Signed-off-by: Angelo Dureghello <adureghello@...libre.com>
> ---

With the improved change and the inline note:

Reviewed-by: Nuno Sa <nuno.sa@...log.com>

>  drivers/iio/dac/ad3552r-hs.h  |  8 ++++++++
>  drivers/iio/dac/adi-axi-dac.c | 22 +++++++++++++++++++++-
>  2 files changed, 29 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/dac/ad3552r-hs.h b/drivers/iio/dac/ad3552r-hs.h
> index 724261d38dea..4a9e35234124 100644
> --- a/drivers/iio/dac/ad3552r-hs.h
> +++ b/drivers/iio/dac/ad3552r-hs.h
> @@ -8,11 +8,19 @@
>  
>  struct iio_backend;
>  
> +enum ad3552r_io_mode {
> +	AD3552R_IO_MODE_SPI,
> +	AD3552R_IO_MODE_DSPI,
> +	AD3552R_IO_MODE_QSPI,
> +};
> +
>  struct ad3552r_hs_platform_data {
>  	int (*bus_reg_read)(struct iio_backend *back, u32 reg, u32 *val,
>  			    size_t data_size);
>  	int (*bus_reg_write)(struct iio_backend *back, u32 reg, u32 val,
>  			     size_t data_size);
> +	int (*bus_set_io_mode)(struct iio_backend *back,
> +			       enum ad3552r_io_mode mode);
>  	u32 bus_sample_data_clock_hz;
>  };
>  
> diff --git a/drivers/iio/dac/adi-axi-dac.c b/drivers/iio/dac/adi-axi-dac.c
> index ac871deb8063..bcaf365feef4 100644
> --- a/drivers/iio/dac/adi-axi-dac.c
> +++ b/drivers/iio/dac/adi-axi-dac.c
> @@ -64,7 +64,7 @@
>  #define   AXI_DAC_UI_STATUS_IF_BUSY		BIT(4)
>  #define AXI_DAC_CUSTOM_CTRL_REG			0x008C
>  #define   AXI_DAC_CUSTOM_CTRL_ADDRESS		GENMASK(31, 24)
> -#define   AXI_DAC_CUSTOM_CTRL_SYNCED_TRANSFER	BIT(2)
> +#define   AXI_DAC_CUSTOM_CTRL_MULTI_IO_MODE	GENMASK(3, 2)
>  #define   AXI_DAC_CUSTOM_CTRL_STREAM		BIT(1)
>  #define   AXI_DAC_CUSTOM_CTRL_TRANSFER_DATA	BIT(0)
>  
> @@ -722,6 +722,25 @@ static int axi_dac_bus_reg_read(struct iio_backend *back,
> u32 reg, u32 *val,
>  	return regmap_read(st->regmap, AXI_DAC_CUSTOM_RD_REG, val);
>  }
>  
> +static int axi_dac_bus_set_io_mode(struct iio_backend *back,
> +				   enum ad3552r_io_mode mode)
> +{
> +	struct axi_dac_state *st = iio_backend_get_priv(back);
> +	int ival, ret;
> +

No harm in doing some validation on 'mode'.

- Nuno Sá

> +	guard(mutex)(&st->lock);
> +
> +	ret = regmap_update_bits(st->regmap, AXI_DAC_CUSTOM_CTRL_REG,
> +			AXI_DAC_CUSTOM_CTRL_MULTI_IO_MODE,
> +			FIELD_PREP(AXI_DAC_CUSTOM_CTRL_MULTI_IO_MODE, mode));
> +	if (ret)
> +		return ret;
> +
> +	return regmap_read_poll_timeout(st->regmap, AXI_DAC_UI_STATUS_REG,
> ival,
> +			FIELD_GET(AXI_DAC_UI_STATUS_IF_BUSY, ival) == 0, 10,
> +			100 * KILO);
> +}
> +
>  static void axi_dac_child_remove(void *data)
>  {
>  	platform_device_unregister(data);
> @@ -733,6 +752,7 @@ static int axi_dac_create_platform_device(struct
> axi_dac_state *st,
>  	struct ad3552r_hs_platform_data pdata = {
>  		.bus_reg_read = axi_dac_bus_reg_read,
>  		.bus_reg_write = axi_dac_bus_reg_write,
> +		.bus_set_io_mode = axi_dac_bus_set_io_mode,
>  		.bus_sample_data_clock_hz = st->dac_clk_rate,
>  	};
>  	struct platform_device_info pi = {
>