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>
---
 drivers/iio/adc/adi-axi-adc.c | 79 ++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 74 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/adc/adi-axi-adc.c b/drivers/iio/adc/adi-axi-adc.c
index 5c8c87eb36d1..704ebd6ea83e 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 +336,40 @@ static const struct regmap_config axi_adc_regmap_config = {
 	.reg_stride = 4,
 };
 
+static void axi_adc_child_remove(void *data)
+{
+	struct adi_axi_adc_state *st = data;
+
+	platform_device_unregister(st->adc_pdev);
+}
+
+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);
+
+	st->adc_pdev = pdev;
+
+	ret = devm_add_action_or_reset(st->dev, axi_adc_child_remove, st);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
 static const struct iio_backend_ops adi_axi_adc_ops = {
 	.enable = axi_adc_enable,
 	.disable = axi_adc_disable,
@@ -370,7 +415,9 @@ 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);
+	st->info = device_get_match_data(&pdev->dev);
+
+	expected_ver = &st->info->version;
 	if (!expected_ver)
 		return -ENODEV;
 
@@ -408,6 +455,25 @@ 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);
+			if (ret)
+				continue;
+
+			ret = axi_adc_create_platform_device(st, child);
+			if (ret)
+				continue;
+		}
+	}
+
 	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),
@@ -416,12 +482,15 @@ 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 },
-	{ /* end of list */ }
+	{ .compatible = "adi,axi-adc-10.0.a", .data = &adc_generic },
+	{  }
 };
 MODULE_DEVICE_TABLE(of, adi_axi_adc_of_match);
 

-- 
2.34.1