Re: [PATCH v6 2/5] remoteproc: imx_rproc: Populate devices under "rpmsg" subnode

[Arnaud POULIQUEN <arnaud.pouliquen@foss.st.com>]

Hello,

On 12/12/25 20:43, Shenwei Wang wrote:
> Register the RPMsg channel driver and populate remote devices defined
> under the "rpmsg" subnode upon receiving their notification messages.
> 
> The following illustrates the expected DTS layout structure:
> 
> 	cm33: remoteproc-cm33 {
> 		compatible = "fsl,imx8ulp-cm33";
> 
> 		rpmsg {
> 			rpmsg-io-channel {
> 				gpio@0 {
> 					compatible = "fsl,imx-rpmsg-gpio";
> 					reg = <0>;
> 				};
> 
> 				gpio@1 {
> 					compatible = "fsl,imx-rpmsg-gpio";
> 					reg = <1>;
> 				};
> 
> 				...
> 			};
> 
> 			...
> 		};
> 	};
> 
> Signed-off-by: Shenwei Wang <shenwei.wang@nxp.com>
> ---
>   drivers/remoteproc/imx_rproc.c   | 143 +++++++++++++++++++++++++++++++
>   include/linux/rpmsg/rpdev_info.h |  33 +++++++
>   2 files changed, 176 insertions(+)
>   create mode 100644 include/linux/rpmsg/rpdev_info.h
> 
> diff --git a/drivers/remoteproc/imx_rproc.c b/drivers/remoteproc/imx_rproc.c
> index 33f21ab24c92..65ee16fd66d1 100644
> --- a/drivers/remoteproc/imx_rproc.c
> +++ b/drivers/remoteproc/imx_rproc.c
> @@ -15,6 +15,8 @@
>   #include <linux/module.h>
>   #include <linux/of.h>
>   #include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_platform.h>
>   #include <linux/of_reserved_mem.h>
>   #include <linux/platform_device.h>
>   #include <linux/pm_domain.h>
> @@ -22,6 +24,8 @@
>   #include <linux/reboot.h>
>   #include <linux/regmap.h>
>   #include <linux/remoteproc.h>
> +#include <linux/rpmsg.h>
> +#include <linux/rpmsg/rpdev_info.h>
>   #include <linux/workqueue.h>
>   
>   #include "imx_rproc.h"
> @@ -1016,6 +1020,141 @@ static void imx_rproc_destroy_workqueue(void *data)
>   	destroy_workqueue(workqueue);
>   }
>   
> +struct imx_rpmsg_driver {
> +	struct rpmsg_driver rpdrv;
> +	const char *compat;
> +	void *driver_data;
> +};
> +
> +static const char *channel_device_map[][2] = {
> +	{"rpmsg-io-channel", "rpmsg-gpio"},
> +};
> +
> +static int imx_rpmsg_endpoint_cb(struct rpmsg_device *rpdev, void *data,
> +				 int len, void *priv, u32 src)
> +{
> +	struct rpdev_platform_info *drvdata;
> +
> +	drvdata = dev_get_drvdata(&rpdev->dev);
> +	if (drvdata && drvdata->rx_callback)
> +		return drvdata->rx_callback(rpdev, data, len, priv, src);
> +
> +	return 0;
> +}
> +
> +static void imx_rpmsg_endpoint_remove(struct rpmsg_device *rpdev)
> +{
> +	of_platform_depopulate(&rpdev->dev);
> +}
> +
> +static int imx_rpmsg_endpoint_probe(struct rpmsg_device *rpdev)
> +{
> +	struct rpdev_platform_info *drvdata;
> +	struct imx_rpmsg_driver *imx_rpdrv;
> +	struct device *dev = &rpdev->dev;
> +	struct of_dev_auxdata *auxdata;
> +	struct rpmsg_driver *rpdrv;
> +
> +	rpdrv = container_of(dev->driver, struct rpmsg_driver, drv);
> +	imx_rpdrv = container_of(rpdrv, struct imx_rpmsg_driver, rpdrv);
> +
> +	if (!imx_rpdrv->driver_data)
> +		return -EINVAL;
> +
> +	drvdata = devm_kmemdup(dev, imx_rpdrv->driver_data, sizeof(*drvdata), GFP_KERNEL);
> +	if (!drvdata)
> +		return -ENOMEM;
> +
> +	auxdata = devm_kzalloc(dev, sizeof(*auxdata) * 2, GFP_KERNEL);
> +	if (!auxdata)
> +		return -ENOMEM;
> +
> +	drvdata->rpdev = rpdev;
> +	auxdata[0].compatible = devm_kstrdup(dev, imx_rpdrv->compat, GFP_KERNEL);
> +	auxdata[0].platform_data = drvdata;
> +	dev_set_drvdata(dev, drvdata);
> +
> +	of_platform_populate(drvdata->channel_node, NULL, auxdata, dev);
> +
> +	return 0;
> +}
> +
> +static const char *imx_of_rpmsg_is_in_map(const char *name)
> +{
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(channel_device_map); i++) {
> +		if (strcmp(name, channel_device_map[i][0]) == 0)
> +			return channel_device_map[i][1];
> +	}
> +
> +	return NULL;
> +}
> +
> +static int imx_of_rpmsg_register_rpdriver(struct device_node *channel,
> +					  struct device *dev,
> +					  const char *name,
> +					  const char *compat)
> +{
> +	struct rpdev_platform_info *driver_data;
> +	struct imx_rpmsg_driver *rp_driver;
> +	struct rpmsg_device_id *rpdev_id;
> +
> +	/* rpmsg_device_id is a NULL terminated array */
> +	rpdev_id = devm_kzalloc(dev, sizeof(*rpdev_id) * 2, GFP_KERNEL);
> +	if (!rpdev_id)
> +		return -ENOMEM;
> +
> +	strscpy(rpdev_id[0].name, name, RPMSG_NAME_SIZE);
> +
> +	rp_driver = devm_kzalloc(dev, sizeof(*rp_driver), GFP_KERNEL);
> +	if (!rp_driver)
> +		return -ENOMEM;
> +
> +	driver_data = devm_kzalloc(dev, sizeof(*driver_data), GFP_KERNEL);
> +	if (!driver_data)
> +		return -ENOMEM;
> +
> +	driver_data->rproc_name = dev->of_node->name;
> +	driver_data->channel_node = channel;
> +
> +	rp_driver->rpdrv.drv.name = name;
> +	rp_driver->rpdrv.id_table = rpdev_id;
> +	rp_driver->rpdrv.probe = imx_rpmsg_endpoint_probe;
> +	rp_driver->rpdrv.remove = imx_rpmsg_endpoint_remove;
> +	rp_driver->rpdrv.callback = imx_rpmsg_endpoint_cb;
> +	rp_driver->driver_data = driver_data;
> +	rp_driver->compat = compat;
> +
> +	register_rpmsg_driver(&rp_driver->rpdrv);


I still believe that creating a dependency between remoteproc and rpmsg 
is not suitable.

Please correct me if I’m wrong, but since you define gpio@0 and gpio@1 
in your device tree, you call register_rpmsg_driver() twice, creating 
two instances of the same driver. To differentiate both, you fill the 
rpdrv.id_table with the node names "gpio@0" and "gpio@1".

In a topology with two remote processors, each needing rpmsg-gpio, the 
same situation would not work because you would have two "gpio@0" entries.

What about using the ns-announcement mechanism on the remote side to 
address GPIO port/bank instances?

In the rpmsg-gpio driver, you could define:

static struct rpmsg_device_id rpmsg_gpio_id_table[] = {
     { .name = "rpmsg-gpio" },
     { .name = "rpmsg_gpio-0" },
     { .name = "rpmsg_gpio-1" },
     { .name = "rpmsg_gpio-2" },
     { .name = "rpmsg_gpio-3" },
     { },
};

Then the match between the device tree and the rpmsg bus could be done 
in the rpmsg-gpio driver by matching the rpmsg name with the compatible 
property plus the reg value.

Example device tree snippet:

cm33: remoteproc-cm33 {
     compatible = "fsl,imx8ulp-cm33";

     rpmsg {
         rpmsg-io-channel {
             gpio@0 {
                 compatible = "rpmsg_gpio";
                 reg = <0>;
             };

             gpio@1 {
                 compatible = "rpmsg_gpio";
                 reg = <1>;
             };

             ...
         };

         ...
     };
};

With this approach, rpmsg management could be handled entirely within 
the rpmsg-gpio driver, avoiding the need to register multiple instances 
of the rpmsg_gpio driver.

Regards,
Arnaud

> +
> +	return 0;
> +}
> +
> +static int rproc_of_rpmsg_node_init(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	const char *compat;
> +	int ret;
> +
> +	struct device_node *np __free(device_node) = of_get_child_by_name(dev->of_node, "rpmsg");
> +	if (!np)
> +		return 0;
> +
> +	for_each_child_of_node_scoped(np, child) {
> +		compat = imx_of_rpmsg_is_in_map(child->name);
> +		if (!compat)
> +			ret = of_platform_default_populate(child, NULL, dev);
> +		else
> +			ret = imx_of_rpmsg_register_rpdriver(child, dev, child->name, compat);
> +
> +		if (ret < 0)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
>   static int imx_rproc_probe(struct platform_device *pdev)
>   {
>   	struct device *dev = &pdev->dev;
> @@ -1114,6 +1253,10 @@ static int imx_rproc_probe(struct platform_device *pdev)
>   		goto err_put_pm;
>   	}
>   
> +	ret = rproc_of_rpmsg_node_init(pdev);
> +	if (ret < 0)
> +		dev_info(dev, "populating 'rpmsg' node failed\n");
> +
>   	return 0;
>   
>   err_put_pm:
> diff --git a/include/linux/rpmsg/rpdev_info.h b/include/linux/rpmsg/rpdev_info.h
> new file mode 100644
> index 000000000000..13e020cd028b
> --- /dev/null
> +++ b/include/linux/rpmsg/rpdev_info.h
> @@ -0,0 +1,33 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* Copyright 2025 NXP */
> +
> +/*
> + * @file linux/rpdev_info.h
> + *
> + * @brief Global header file for RPDEV Info
> + *
> + * @ingroup RPMSG
> + */
> +#ifndef __LINUX_RPDEV_INFO_H__
> +#define __LINUX_RPDEV_INFO_H__
> +
> +#define MAX_DEV_PER_CHANNEL    10
> +
> +/**
> + * rpdev_platform_info - store the platform information of rpdev
> + * @rproc_name: the name of the remote proc.
> + * @rpdev: rpmsg channel device
> + * @device_node: pointer to the device node of the rpdev.
> + * @rx_callback: rx callback handler of the rpdev.
> + * @channel_devices: an array of the devices related to the rpdev.
> + */
> +struct rpdev_platform_info {
> +	const char *rproc_name;
> +	struct rpmsg_device *rpdev;
> +	struct device_node *channel_node;
> +	int (*rx_callback)(struct rpmsg_device *rpdev, void *data,
> +			   int len, void *priv, u32 src);
> +	void *channel_devices[MAX_DEV_PER_CHANNEL];
> +};
> +
> +#endif /* __LINUX_RPDEV_INFO_H__ */