Re: [PATCH v3 06/10] iio: adc: adi-axi-adc: add platform children support

[David Lechner <dlechner@baylibre.com>]

On 1/29/25 5:03 AM, Angelo Dureghello wrote:
> From: Guillaume Stols <gstols@baylibre.com>
> 
> This is a preparation for the next commit adding support for register
> read and write functions on AD7606.
> Since sometimes a bus will be used, it has been agreed during ad3552's
> driver implementation that the device's driver bus is the backend, whose
> device node will be a child node.
> To provide the special callbacks for setting the register, axi-adc needs
> to pass them to the child device's driver through platform data.
> 
> Signed-off-by: Guillaume Stols <gstols@baylibre.com>
> Co-developed-by: Angelo Dureghello <adureghello@baylibre.com>
> Signed-off-by: Angelo Dureghello <adureghello@baylibre.com>
> ---
>  drivers/iio/adc/ad7606_bus_iface.h | 16 ++++++++
>  drivers/iio/adc/adi-axi-adc.c      | 84 ++++++++++++++++++++++++++++++++++----
>  2 files changed, 91 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7606_bus_iface.h b/drivers/iio/adc/ad7606_bus_iface.h
> new file mode 100644
> index 000000000000..d8d39822e2a9
> --- /dev/null
> +++ b/drivers/iio/adc/ad7606_bus_iface.h
> @@ -0,0 +1,16 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * Copyright (c) 2010-2024 Analog Devices Inc.
> + * Copyright (c) 2024 Baylibre, SAS

Should update the copyright date to 2025.

> + */
> +#ifndef __LINUX_PLATFORM_DATA_AD7606_H__
> +#define __LINUX_PLATFORM_DATA_AD7606_H__
> +
> +struct iio_backend;
> +
> +struct ad7606_platform_data {
> +	int (*bus_reg_read)(struct iio_backend *back, u32 reg, u32 *val);
> +	int (*bus_reg_write)(struct iio_backend *back, u32 reg, u32 val);
> +};
> +
> +#endif /* __LINUX_PLATFORM_DATA_AD7606_H__ */
> diff --git a/drivers/iio/adc/adi-axi-adc.c b/drivers/iio/adc/adi-axi-adc.c
> index c7357601f0f8..0923565cf5bb 100644
> --- a/drivers/iio/adc/adi-axi-adc.c
> +++ b/drivers/iio/adc/adi-axi-adc.c
> @@ -80,7 +80,18 @@
>  	 ADI_AXI_REG_CHAN_CTRL_FMT_EN |		\
>  	 ADI_AXI_REG_CHAN_CTRL_ENABLE)
>  
> +struct axi_adc_info {
> +	unsigned int version;
> +	const struct iio_backend_info *backend_info;
> +	bool bus_controller;
> +	const void *pdata;
> +	unsigned int pdata_sz;
> +};
> +
>  struct adi_axi_adc_state {
> +	/* Target ADC platform device */
> +	struct platform_device *adc_pdev;
> +	const struct axi_adc_info *info;
>  	struct regmap *regmap;
>  	struct device *dev;
>  	/* lock to protect multiple accesses to the device registers */
> @@ -325,6 +336,38 @@ static const struct regmap_config axi_adc_regmap_config = {
>  	.reg_stride = 4,
>  };
>  
> +static void axi_adc_child_remove(void *data)
> +{
> +	platform_device_unregister(data);
> +}
> +
> +static int axi_adc_create_platform_device(struct adi_axi_adc_state *st,
> +					  struct fwnode_handle *child)
> +{
> +	struct platform_device_info pi = {
> +		.parent = st->dev,
> +		.name = fwnode_get_name(child),
> +		.id = PLATFORM_DEVID_AUTO,
> +		.fwnode = child,
> +		.data = st->info->pdata,
> +		.size_data = st->info->pdata_sz,
> +	};
> +	struct platform_device *pdev;
> +	int ret;
> +
> +	pdev = platform_device_register_full(&pi);
> +	if (IS_ERR(pdev))
> +		return PTR_ERR(pdev);
> +
> +	ret = devm_add_action_or_reset(st->dev, axi_adc_child_remove, pdev);
> +	if (ret)
> +		return ret;
> +
> +	st->adc_pdev = pdev;

st->adc_pdev is written but not read, so I think we can remove that field.

> +
> +	return 0;
> +}
> +
>  static const struct iio_backend_ops adi_axi_adc_ops = {
>  	.enable = axi_adc_enable,
>  	.disable = axi_adc_disable,
> @@ -348,7 +391,6 @@ static const struct iio_backend_info adi_axi_adc_generic = {
>  
>  static int adi_axi_adc_probe(struct platform_device *pdev)
>  {
> -	const unsigned int *expected_ver;
>  	struct adi_axi_adc_state *st;
>  	void __iomem *base;
>  	unsigned int ver;
> @@ -370,8 +412,8 @@ static int adi_axi_adc_probe(struct platform_device *pdev)
>  		return dev_err_probe(&pdev->dev, PTR_ERR(st->regmap),
>  				     "failed to init register map\n");
>  
> -	expected_ver = device_get_match_data(&pdev->dev);
> -	if (!expected_ver)
> +	st->info = device_get_match_data(&pdev->dev);
> +	if (!st->info)
>  		return -ENODEV;
>  
>  	clk = devm_clk_get_enabled(&pdev->dev, NULL);
> @@ -391,12 +433,13 @@ static int adi_axi_adc_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> -	if (ADI_AXI_PCORE_VER_MAJOR(ver) != ADI_AXI_PCORE_VER_MAJOR(*expected_ver)) {
> +	if (ADI_AXI_PCORE_VER_MAJOR(ver) !=
> +	    ADI_AXI_PCORE_VER_MAJOR(st->info->version)) {
>  		dev_err(&pdev->dev,
>  			"Major version mismatch. Expected %d.%.2d.%c, Reported %d.%.2d.%c\n",
> -			ADI_AXI_PCORE_VER_MAJOR(*expected_ver),
> -			ADI_AXI_PCORE_VER_MINOR(*expected_ver),
> -			ADI_AXI_PCORE_VER_PATCH(*expected_ver),
> +			ADI_AXI_PCORE_VER_MAJOR(st->info->version),
> +			ADI_AXI_PCORE_VER_MINOR(st->info->version),
> +			ADI_AXI_PCORE_VER_PATCH(st->info->version),
>  			ADI_AXI_PCORE_VER_MAJOR(ver),
>  			ADI_AXI_PCORE_VER_MINOR(ver),
>  			ADI_AXI_PCORE_VER_PATCH(ver));
> @@ -408,6 +451,26 @@ static int adi_axi_adc_probe(struct platform_device *pdev)
>  		return dev_err_probe(&pdev->dev, ret,
>  				     "failed to register iio backend\n");
>  
> +	if (st->info->bus_controller) {
> +		device_for_each_child_node_scoped(&pdev->dev, child) {
> +			int val;
> +
> +			/* Processing only reg 0 node */
> +			ret = fwnode_property_read_u32(child, "reg", &val);
> +			if (ret || val != 0)
> +				continue;
> +
> +			ret = fwnode_property_read_u32(child, "io-backends",
> +						       &val);

This one is a phandl array. But since val isn't used, I'm guessing that this
should be fwnode_property_present().

Although, I'm not really sure we need this check at all since the driver for
the child node will be checking it.

> +			if (ret)
> +				continue;
> +
> +			ret = axi_adc_create_platform_device(st, child);
> +			if (ret)
> +				return ret;
> +		}
> +	}
> +
>  	dev_info(&pdev->dev, "AXI ADC IP core (%d.%.2d.%c) probed\n",
>  		 ADI_AXI_PCORE_VER_MAJOR(ver),
>  		 ADI_AXI_PCORE_VER_MINOR(ver),
> @@ -416,11 +479,14 @@ static int adi_axi_adc_probe(struct platform_device *pdev)
>  	return 0;
>  }
>  
> -static unsigned int adi_axi_adc_10_0_a_info = ADI_AXI_PCORE_VER(10, 0, 'a');
> +static const struct axi_adc_info adc_generic = {
> +	.version = ADI_AXI_PCORE_VER(10, 0, 'a'),
> +	.backend_info = &adi_axi_adc_generic,
> +};
>  
>  /* Match table for of_platform binding */
>  static const struct of_device_id adi_axi_adc_of_match[] = {
> -	{ .compatible = "adi,axi-adc-10.0.a", .data = &adi_axi_adc_10_0_a_info },
> +	{ .compatible = "adi,axi-adc-10.0.a", .data = &adc_generic },
>  	{ /* end of list */ }
>  };
>  MODULE_DEVICE_TABLE(of, adi_axi_adc_of_match);
>