Re: [PATCH v13 3/4] gpio: rpmsg: add generic rpmsg GPIO driver

Shenwei Wang
2026-04-27T19:23:52Z

> -----Original Message-----
> From: Padhi, Beleswar <b-padhi@ti.com>
> Sent: Sunday, April 26, 2026 7:44 AM
> To: Shenwei Wang <shenwei.wang@nxp.com>; Linus Walleij
> <linusw@kernel.org>; Bartosz Golaszewski <brgl@kernel.org>; Jonathan Corbet
> <corbet@lwn.net>; Rob Herring <robh@kernel.org>; Krzysztof Kozlowski
> <krzk+dt@kernel.org>; Conor Dooley <conor+dt@kernel.org>; Bjorn Andersson
> <andersson@kernel.org>; Mathieu Poirier <mathieu.poirier@linaro.org>; Frank Li
> <frank.li@nxp.com>; Sascha Hauer <s.hauer@pengutronix.de>
> Cc: Shuah Khan <skhan@linuxfoundation.org>; linux-gpio@vger.kernel.org; linux-
> doc@vger.kernel.org; linux-kernel@vger.kernel.org; Pengutronix Kernel Team
> <kernel@pengutronix.de>; Fabio Estevam <festevam@gmail.com>; Peng Fan
> <peng.fan@nxp.com>; devicetree@vger.kernel.org; linux-
> remoteproc@vger.kernel.org; imx@lists.linux.dev; linux-arm-
> kernel@lists.infradead.org; dl-linux-imx <linux-imx@nxp.com>; Bartosz
> Golaszewski <brgl@bgdev.pl>; Andrew Lunn <andrew@lunn.ch>
> Subject: [EXT] Re: [PATCH v13 3/4] gpio: rpmsg: add generic rpmsg GPIO driver
> Hello Shenwei, Greetings,
>
> On 4/23/2026 2:58 AM, Shenwei Wang wrote:
> > On an AMP platform, the system may include two processors:
>
>
> s/two/multiple
>
> > - An MCU running an RTOS
>
>
> s/An MCU/MCUs
>
> > - An MPU running Linux
> >
> > These processors communicate via the RPMSG protocol.
> > The driver implements the standard GPIO interface, allowing the Linux
> > side to control GPIO controllers which reside in the remote processor
> > via RPMSG protocol.
> >
> > Cc: Bartosz Golaszewski <brgl@bgdev.pl>
> > Cc: Andrew Lunn <andrew@lunn.ch>
> > Signed-off-by: Shenwei Wang <shenwei.wang@nxp.com>
> > ---
> > drivers/gpio/Kconfig | 17 ++
> > drivers/gpio/Makefile | 1 +
> > drivers/gpio/gpio-rpmsg.c | 573
> ++++++++++++++++++++++++++++++++++++++
> > 3 files changed, 591 insertions(+)
> > create mode 100644 drivers/gpio/gpio-rpmsg.c
> >
> > diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig index
> > 020e51e30317..4ad299fe3c6f 100644
> > --- a/drivers/gpio/Kconfig
> > +++ b/drivers/gpio/Kconfig
> > @@ -1917,6 +1917,23 @@ config GPIO_SODAVILLE
> >
> > endmenu
> >
> > +menu "RPMSG GPIO drivers"
> > + depends on RPMSG
> > +
> > +config GPIO_RPMSG
> > + tristate "Generic RPMSG GPIO support"
> > + depends on OF && REMOTEPROC
> > + select GPIOLIB_IRQCHIP
> > + default REMOTEPROC
> > + help
> > + Say yes here to support the generic GPIO functions over the RPMSG
> > + bus. Currently supported devices: i.MX7ULP, i.MX8ULP, i.MX8x, and
> > + i.MX9x.
> > +
> > + If unsure, say N.
> > +
> > +endmenu
> > +
> > menu "SPI GPIO expanders"
> > depends on SPI_MASTER
> >
> > diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile index
> > b267598b517d..ee75c0e65b8b 100644
> > --- a/drivers/gpio/Makefile
> > +++ b/drivers/gpio/Makefile
> > @@ -157,6 +157,7 @@ obj-$(CONFIG_GPIO_RDC321X) += gpio-
> rdc321x.o
> > obj-$(CONFIG_GPIO_REALTEK_OTTO) += gpio-realtek-otto.o
> > obj-$(CONFIG_GPIO_REG) += gpio-reg.o
> > obj-$(CONFIG_GPIO_ROCKCHIP) += gpio-rockchip.o
> > +obj-$(CONFIG_GPIO_RPMSG) += gpio-rpmsg.o
> > obj-$(CONFIG_GPIO_RTD) += gpio-rtd.o
> > obj-$(CONFIG_ARCH_SA1100) += gpio-sa1100.o
> > obj-$(CONFIG_GPIO_SAMA5D2_PIOBU) += gpio-sama5d2-piobu.o
> > diff --git a/drivers/gpio/gpio-rpmsg.c b/drivers/gpio/gpio-rpmsg.c new
> > file mode 100644 index 000000000000..993cde7af2fa
> > --- /dev/null
> > +++ b/drivers/gpio/gpio-rpmsg.c
> > @@ -0,0 +1,573 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Copyright 2026 NXP
> > + *
> > + * The driver exports a standard gpiochip interface to control
> > + * the GPIO controllers via RPMSG on a remote processor.
> > + */
> > +
> > +#include <linux/completion.h>
> > +#include <linux/device.h>
> > +#include <linux/err.h>
> > +#include <linux/gpio/driver.h>
> > +#include <linux/init.h>
> > +#include <linux/irqdomain.h>
> > +#include <linux/mod_devicetable.h>
> > +#include <linux/module.h>
> > +#include <linux/mutex.h>
> > +#include <linux/of.h>
> > +#include <linux/of_device.h>
> > +#include <linux/of_platform.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/remoteproc.h>
> > +#include <linux/rpmsg.h>
> > +#include <linux/virtio_gpio.h>
> > +
> > +#define MAX_PORT_PER_CHANNEL 10
> > +#define GPIOS_PER_PORT_DEFAULT 32
> > +#define RPMSG_TIMEOUT 1000
> > +
> > +/* GPIO RPMSG Type */
> > +#define GPIO_RPMSG_SEND 0
> > +#define GPIO_RPMSG_REPLY 1
> > +#define GPIO_RPMSG_NOTIFY 2
> > +
> > +struct rpmsg_gpio_packet {
> > + u8 type; /* Message type */
> > + u8 cmd; /* Command code */
> > + u8 port_idx;
> > + u8 line;
> > + u8 val1;
> > + u8 val2;
> > +};
>
>
> Could you please document the fields in these structs (and the below ones too)?
> From the code, it looks like while sending a message from Linux to Firmware; val1
> and val2 are used to describe the values to set. Whereas while receiving a
> response, val1 represents a possible error code, and val2 represents the actual
> message of get type queries. If that is so, you might want to change the variable
> names to be more descriptive and also use a union.
>

The fields in the two structs are fairly self-explanatory. Do we really need the additional comments?
The previous version of the patch used a union, which was updated to support the fixed_up hooks.
Now that the fixed_up hooks have been removed, I can revert this back to the union-based implementation.

> > +
> > +struct rpmsg_gpio_line {
> > + u8 irq_shutdown;
> > + u8 irq_unmask;
> > + u8 irq_mask;
> > + u32 irq_wake_enable;
> > + u32 irq_type;
> > + struct rpmsg_gpio_packet msg;
>
>
> We don't need to have this field. More info at [0].
>
> > +};
> > +
> > +struct rpmsg_gpio_info {
> > + struct rpmsg_device *rpdev;
> > + struct rpmsg_gpio_packet *reply_msg;
> > + struct completion cmd_complete;
> > + struct mutex lock;
> > + void **port_store;
> > +};
> > +
> > +struct rpmsg_gpio_port {
> > + struct gpio_chip gc;
> > + struct rpmsg_gpio_line lines[GPIOS_PER_PORT_DEFAULT];
> > + struct rpmsg_gpio_info info;
> > + u32 ngpios;
> > + u32 idx;
> > +};
> > +
> > +/**
> > + * struct rpmsg_drvdata - driver data per channel.
> > + * @rproc_name: the name of the remote proc.
> > + * @recv_pkt: a pointer to the received packet for protocol fix up.
> > + * @channel_devices: an array of the devices related to the rpdev.
> > + */
> > +struct rpdev_drvdata {
> > + const char *rproc_name;
> > + void *recv_pkt;
>
>
> I don't see any use of this field in the code?
>

Will remove it. It was there for fixed_up hooks.

> > + void *channel_devices[MAX_PORT_PER_CHANNEL];
>
>
> So this is technically a rpmsg endpoint (struct rpmsg_endpoint) without naming it
> "endpoint". Every rpmsg endpoint has a reference to its parent rpmsg channel
> (struct rpmsg_device) which represents the same information here. So we should
> use the framework standard here.
>

Yes, agree to use "endpoint_devices".

> This also allows for dynamic creation and deletion of ports too! (if/when the
> firmware supports it)
>
> Which means at port init time, we should make a call to
> rpmsg_create_ept() for each port tying the same callback
> rpmsg_gpio_channel_callback(). And based on the 'u32 src', we could identify the
> appropriate gpio port in the callback.
>
> > +};
> > +
> > +static int rpmsg_gpio_send_message(struct rpmsg_gpio_port *port,
> > + struct rpmsg_gpio_packet *msg) {
> > + struct rpmsg_gpio_info *info = &port->info;
> > + int ret;
> > +
> > + reinit_completion(&info->cmd_complete);
> > +
> > + ret = rpmsg_send(info->rpdev->ept, msg, sizeof(*msg));
> > + if (ret) {
> > + dev_err(&info->rpdev->dev, "rpmsg_send failed: %d\n", ret);
> > + return ret;
> > + }
> > +
> > + ret = wait_for_completion_timeout(&info->cmd_complete,
> > + msecs_to_jiffies(RPMSG_TIMEOUT));
> > + if (ret == 0) {
> > + dev_err(&info->rpdev->dev, "rpmsg_send timeout!\n");
> > + return -ETIMEDOUT;
> > + }
> > +
> > + if (info->reply_msg->val1) {
> > + dev_err(&info->rpdev->dev, "remote core replies an error: %d!\n",
> > + info->reply_msg->val1);
> > + return -EINVAL;
> > + }
> > +
> > + /* copy the reply message */
> > + memcpy(&port->lines[info->reply_msg->line].msg,
> > + info->reply_msg, sizeof(*info->reply_msg));
>
>
> The rpmsg_gpio_port structure already holds a pointer to the reply message via -
> >info. We do not need this extra copy. More info at [0].
>
> > +
> > + return 0;
> > +}
> > +
> > +static struct rpmsg_gpio_packet *
> > +rpmsg_gpio_msg_init_common(struct rpmsg_gpio_port *port, unsigned int
> > +line, u8 cmd) {
> > + struct rpmsg_gpio_packet *msg = &port->lines[line].msg;
>
>
> [0]: We really don't need to carry the stale message in the line structure
> everytime. While sending requests, we should just request a buffer from kzalloc
> and use it everytime. As far as response is concerned, we are holding a lock
> everytime we are sending any message, so we are sure the pointer in info-
> >reply_msg would have the response to only one request that was sent.
>

looks reasonable.

> > +
> > + memset(msg, 0, sizeof(*msg));
>
>
> This also means we can get rid of this memset.
>
> > + msg->type = GPIO_RPMSG_SEND;
> > + msg->cmd = cmd;
> > + msg->port_idx = port->idx;
> > + msg->line = line;
> > +
> > + return msg;
> > +}
> > +
> > +static int rpmsg_gpio_get(struct gpio_chip *gc, unsigned int line) {
> > + struct rpmsg_gpio_port *port = gpiochip_get_data(gc);
> > + struct rpmsg_gpio_packet *msg;
> > + int ret;
> > +
> > + guard(mutex)(&port->info.lock);
> > +
> > + msg = rpmsg_gpio_msg_init_common(port, line,
> > + VIRTIO_GPIO_MSG_GET_VALUE);
> > +
> > + ret = rpmsg_gpio_send_message(port, msg);
> > + if (!ret)
> > + ret = !!port->lines[line].msg.val2;
>
>
> Which means here & everywhere else, we could just read the reply message
> from !!port->info->reply_msg->val2
>
> > +
> > + return ret;
> > +}
> > +
> > +static int rpmsg_gpio_get_direction(struct gpio_chip *gc, unsigned
> > +int line) {
> > + struct rpmsg_gpio_port *port = gpiochip_get_data(gc);
> > + struct rpmsg_gpio_packet *msg;
> > + int ret;
> > +
> > + guard(mutex)(&port->info.lock);
> > +
> > + msg = rpmsg_gpio_msg_init_common(port, line,
> > + VIRTIO_GPIO_MSG_GET_DIRECTION);
> > +
> > + ret = rpmsg_gpio_send_message(port, msg);
> > + if (ret)
> > + return ret;
> > +
> > + switch (port->lines[line].msg.val2) {
> > + case VIRTIO_GPIO_DIRECTION_IN:
> > + return GPIO_LINE_DIRECTION_IN;
> > + case VIRTIO_GPIO_DIRECTION_OUT:
> > + return GPIO_LINE_DIRECTION_OUT;
> > + default:
> > + break;
> > + }
> > +
> > + return -EINVAL;
> > +}
> > +
> > +static int rpmsg_gpio_direction_input(struct gpio_chip *gc, unsigned
> > +int line) {
> > + struct rpmsg_gpio_port *port = gpiochip_get_data(gc);
> > + struct rpmsg_gpio_packet *msg;
> > +
> > + guard(mutex)(&port->info.lock);
> > +
> > + msg = rpmsg_gpio_msg_init_common(port, line,
> VIRTIO_GPIO_MSG_SET_DIRECTION);
> > + msg->val1 = VIRTIO_GPIO_DIRECTION_IN;
> > +
> > + return rpmsg_gpio_send_message(port, msg); }
> > +
> > +static int rpmsg_gpio_set(struct gpio_chip *gc, unsigned int line,
> > +int val) {
> > + struct rpmsg_gpio_port *port = gpiochip_get_data(gc);
> > + struct rpmsg_gpio_packet *msg;
> > +
> > + guard(mutex)(&port->info.lock);
> > +
> > + msg = rpmsg_gpio_msg_init_common(port, line,
> VIRTIO_GPIO_MSG_SET_VALUE);
> > + msg->val1 = val;
> > +
> > + return rpmsg_gpio_send_message(port, msg); }
> > +
> > +static int rpmsg_gpio_direction_output(struct gpio_chip *gc, unsigned
> > +int line, int val) {
> > + struct rpmsg_gpio_port *port = gpiochip_get_data(gc);
> > + struct rpmsg_gpio_packet *msg;
> > + int ret;
> > +
> > + guard(mutex)(&port->info.lock);
> > +
> > + msg = rpmsg_gpio_msg_init_common(port, line,
> VIRTIO_GPIO_MSG_SET_DIRECTION);
> > + msg->val1 = VIRTIO_GPIO_DIRECTION_OUT;
> > +
> > + ret = rpmsg_gpio_send_message(port, msg);
> > + if (ret)
> > + return ret;
> > +
> > + msg = rpmsg_gpio_msg_init_common(port, line,
> VIRTIO_GPIO_MSG_SET_VALUE);
> > + msg->val1 = val;
> > +
> > + return rpmsg_gpio_send_message(port, msg); }
> > +
> > +static int gpio_rpmsg_irq_set_type(struct irq_data *d, u32 type) {
> > + struct rpmsg_gpio_port *port = irq_data_get_irq_chip_data(d);
> > + u32 line = d->hwirq;
> > +
> > + switch (type) {
> > + case IRQ_TYPE_EDGE_RISING:
> > + type = VIRTIO_GPIO_IRQ_TYPE_EDGE_RISING;
> > + irq_set_handler_locked(d, handle_simple_irq);
> > + break;
> > + case IRQ_TYPE_EDGE_FALLING:
> > + type = VIRTIO_GPIO_IRQ_TYPE_EDGE_FALLING;
> > + irq_set_handler_locked(d, handle_simple_irq);
> > + break;
> > + case IRQ_TYPE_EDGE_BOTH:
> > + type = VIRTIO_GPIO_IRQ_TYPE_EDGE_BOTH;
> > + irq_set_handler_locked(d, handle_simple_irq);
> > + break;
> > + case IRQ_TYPE_LEVEL_LOW:
> > + type = VIRTIO_GPIO_IRQ_TYPE_LEVEL_LOW;
> > + irq_set_handler_locked(d, handle_level_irq);
> > + break;
> > + case IRQ_TYPE_LEVEL_HIGH:
> > + type = VIRTIO_GPIO_IRQ_TYPE_LEVEL_HIGH;
> > + irq_set_handler_locked(d, handle_level_irq);
> > + break;
> > + default:
> > + dev_err(&port->info.rpdev->dev, "unsupported irq type: %u\n", type);
> > + return -EINVAL;
> > + }
> > +
> > + port->lines[line].irq_type = type;
> > +
> > + return 0;
> > +}
> > +
> > +static int gpio_rpmsg_irq_set_wake(struct irq_data *d, u32 enable) {
> > + struct rpmsg_gpio_port *port = irq_data_get_irq_chip_data(d);
> > + u32 line = d->hwirq;
> > +
> > + port->lines[line].irq_wake_enable = enable;
> > +
> > + return 0;
> > +}
> > +
> > +/*
> > + * This unmask/mask function is invoked in two situations:
> > + * - when an interrupt is being set up, and
> > + * - after an interrupt has occurred.
> > + *
> > + * The GPIO driver does not access hardware registers directly.
> > + * Instead, it caches all relevant information locally, and then
> > +sends
> > + * the accumulated state to the remote system at this stage.
>
>
> It is actually sent at the .bus_sync_unlock() stage.
>
> > + */
> > +static void gpio_rpmsg_unmask_irq(struct irq_data *d) {
> > + struct rpmsg_gpio_port *port = irq_data_get_irq_chip_data(d);
> > + u32 line = d->hwirq;
> > +
> > + port->lines[line].irq_unmask = 1; }
> > +
> > +static void gpio_rpmsg_mask_irq(struct irq_data *d) {
> > + struct rpmsg_gpio_port *port = irq_data_get_irq_chip_data(d);
> > + u32 line = d->hwirq;
> > +
> > + /*
> > + * When an interrupt occurs, the remote system masks the interrupt
> > + * and then sends a notification to Linux. After Linux processes
> > + * that notification, it sends an RPMsg command back to the remote
> > + * system to unmask the interrupt again.
> > + */
> > + port->lines[line].irq_mask = 1;
> > +}
> > +
> > +static void gpio_rpmsg_irq_shutdown(struct irq_data *d) {
> > + struct rpmsg_gpio_port *port = irq_data_get_irq_chip_data(d);
> > + u32 line = d->hwirq;
> > +
> > + port->lines[line].irq_shutdown = 1; }
> > +
> > +static void gpio_rpmsg_irq_bus_lock(struct irq_data *d) {
> > + struct rpmsg_gpio_port *port = irq_data_get_irq_chip_data(d);
> > +
> > + mutex_lock(&port->info.lock);
> > +}
> > +
> > +static void gpio_rpmsg_irq_bus_sync_unlock(struct irq_data *d) {
> > + struct rpmsg_gpio_port *port = irq_data_get_irq_chip_data(d);
> > + struct rpmsg_gpio_packet *msg;
> > + u32 line = d->hwirq;
> > +
> > + /*
> > + * For mask irq, do nothing here.
> > + * The remote system will mask interrupt after an interrupt occurs,
> > + * and then send a notification to Linux system. After Linux system
> > + * handles the notification, it sends an rpmsg back to the remote
> > + * system to unmask this interrupt again.
> > + */
> > + if (port->lines[line].irq_mask && !port->lines[line].irq_unmask) {
> > + port->lines[line].irq_mask = 0;
> > + mutex_unlock(&port->info.lock);
> > + return;
> > + }
> > +
> > + msg = rpmsg_gpio_msg_init_common(port, line,
> > + VIRTIO_GPIO_MSG_IRQ_TYPE);
> > +
> > + if (port->lines[line].irq_shutdown) {
> > + port->lines[line].irq_shutdown = 0;
> > + msg->val1 = VIRTIO_GPIO_IRQ_TYPE_NONE;
> > + msg->val2 = 0;
> > + } else {
> > + msg->val1 = port->lines[line].irq_type;
> > +
> > + if (port->lines[line].irq_unmask) {
> > + msg->val2 = 0;
> > + port->lines[line].irq_unmask = 0;
> > + } else /* irq set wake */
> > + msg->val2 = port->lines[line].irq_wake_enable;
> > + }
> > +
> > + rpmsg_gpio_send_message(port, msg);
> > + mutex_unlock(&port->info.lock);
> > +}
> > +
> > +static const struct irq_chip gpio_rpmsg_irq_chip = {
> > + .irq_mask = gpio_rpmsg_mask_irq,
> > + .irq_unmask = gpio_rpmsg_unmask_irq,
> > + .irq_set_wake = gpio_rpmsg_irq_set_wake,
> > + .irq_set_type = gpio_rpmsg_irq_set_type,
> > + .irq_shutdown = gpio_rpmsg_irq_shutdown,
> > + .irq_bus_lock = gpio_rpmsg_irq_bus_lock,
> > + .irq_bus_sync_unlock = gpio_rpmsg_irq_bus_sync_unlock,
> > + .flags = IRQCHIP_IMMUTABLE,
> > +};
> > +
> > +static void rpmsg_gpio_remove_action(void *data) {
> > + struct rpmsg_gpio_port *port = data;
> > +
> > + port->info.port_store[port->idx] = NULL; }
> > +
> > +static int rpmsg_gpiochip_register(struct rpmsg_device *rpdev, struct
> > +device_node *np) {
> > + struct rpdev_drvdata *drvdata = dev_get_drvdata(&rpdev->dev);
> > + struct rpmsg_gpio_port *port;
> > + struct gpio_irq_chip *girq;
> > + struct gpio_chip *gc;
> > + int ret;
> > +
> > + port = devm_kzalloc(&rpdev->dev, sizeof(*port), GFP_KERNEL);
> > + if (!port)
> > + return -ENOMEM;
> > +
> > + ret = of_property_read_u32(np, "reg", &port->idx);
> > + if (ret)
> > + return ret;
> > +
> > + if (port->idx >= MAX_PORT_PER_CHANNEL)
> > + return -EINVAL;
> > +
> > + ret = devm_mutex_init(&rpdev->dev, &port->info.lock);
> > + if (ret)
> > + return ret;
> > +
> > + ret = of_property_read_u32(np, "ngpios", &port->ngpios);
> > + if (ret || port->ngpios > GPIOS_PER_PORT_DEFAULT)
> > + port->ngpios = GPIOS_PER_PORT_DEFAULT;
> > +
> > + port->info.reply_msg = devm_kzalloc(&rpdev->dev,
> > + sizeof(*port->info.reply_msg),
> > + GFP_KERNEL);
> > + if (!port->info.reply_msg)
> > + return -ENOMEM;
> > +
> > + init_completion(&port->info.cmd_complete);
> > + port->info.port_store = drvdata->channel_devices;
> > + port->info.port_store[port->idx] = port;
> > + port->info.rpdev = rpdev;
> > +
> > + gc = &port->gc;
> > + gc->owner = THIS_MODULE;
> > + gc->parent = &rpdev->dev;
> > + gc->fwnode = of_fwnode_handle(np);
> > + gc->ngpio = port->ngpios;
> > + gc->base = -1;
> > + gc->label = devm_kasprintf(&rpdev->dev, GFP_KERNEL, "%s-gpio%d",
> > + drvdata->rproc_name, port->idx);
> > +
> > + gc->direction_input = rpmsg_gpio_direction_input;
> > + gc->direction_output = rpmsg_gpio_direction_output;
> > + gc->get_direction = rpmsg_gpio_get_direction;
> > + gc->get = rpmsg_gpio_get;
> > + gc->set = rpmsg_gpio_set;
> > +
> > + girq = &gc->irq;
> > + gpio_irq_chip_set_chip(girq, &gpio_rpmsg_irq_chip);
> > + girq->parent_handler = NULL;
> > + girq->num_parents = 0;
> > + girq->parents = NULL;
> > + girq->chip->name = devm_kasprintf(&rpdev->dev, GFP_KERNEL, "%s-
> gpio%d",
> > + drvdata->rproc_name,
> > + port->idx);
>
>
> We could just re-use gc->label here...

We also want to include the remoteproc name (for example, remoteproc-cm33-gpio0), rather than just gpio0.

>
> > +
> > + ret = devm_add_action_or_reset(&rpdev->dev,
> rpmsg_gpio_remove_action, port);
> > + if (ret)
> > + return ret;
> > +
> > + return devm_gpiochip_add_data(&rpdev->dev, gc, port); }
> > +
> > +static const char *rpmsg_get_rproc_node_name(struct rpmsg_device
> > +*rpdev) {
> > + const char *name = NULL;
> > + struct device_node *np;
> > + struct rproc *rproc;
> > +
> > + rproc = rproc_get_by_child(&rpdev->dev);
> > + if (!rproc)
> > + return NULL;
> > +
> > + np = of_node_get(rproc->dev.of_node);
> > + if (!np && rproc->dev.parent)
> > + np = of_node_get(rproc->dev.parent->of_node);
> > +
> > + if (np) {
> > + name = devm_kstrdup(&rpdev->dev, np->name, GFP_KERNEL);
> > + of_node_put(np);
> > + }
> > +
> > + return name;
> > +}
> > +
> > +static struct device_node *
> > +rpmsg_get_channel_ofnode(struct rpmsg_device *rpdev, char *chan_name)
> > +{
> > + struct device_node *np_chan = NULL, *np;
> > + struct rproc *rproc;
> > +
> > + rproc = rproc_get_by_child(&rpdev->dev);
> > + if (!rproc)
> > + return NULL;
> > +
> > + np = of_node_get(rproc->dev.of_node);
> > + if (!np && rproc->dev.parent)
> > + np = of_node_get(rproc->dev.parent->of_node);
> > +
> > + /* The of_node_put() is performed by of_find_node_by_name(). */
> > + if (np)
> > + np_chan = of_find_node_by_name(np, chan_name);
> > +
> > + return np_chan;
> > +}
> > +
> > +static int rpmsg_gpio_channel_callback(struct rpmsg_device *rpdev, void
> *data,
> > + int len, void *priv, u32 src) {
> > + struct rpmsg_gpio_packet *msg = data;
> > + struct rpmsg_gpio_port *port = NULL;
> > + struct rpdev_drvdata *drvdata;
> > +
> > + drvdata = dev_get_drvdata(&rpdev->dev);
> > + if (!msg || !drvdata)
> > + return -EINVAL;
> > +
> > + if (msg->port_idx < MAX_PORT_PER_CHANNEL)
> > + port = drvdata->channel_devices[msg->port_idx];
> > +
> > + if (!port || msg->line >= port->ngpios) {
> > + dev_err(&rpdev->dev, "wrong port index or line number. port:%d
> line:%d\n",
> > + msg->port_idx, msg->line);
> > + return -EINVAL;
> > + }
> > +
> > + if (msg->type == GPIO_RPMSG_REPLY) {
> > + *port->info.reply_msg = *msg;
> > + complete(&port->info.cmd_complete);
> > + } else if (msg->type == GPIO_RPMSG_NOTIFY) {
> > + generic_handle_domain_irq_safe(port->gc.irq.domain, msg->line);
> > + } else {
> > + dev_err(&rpdev->dev, "wrong command type (0x%x)\n", msg->type);
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int rpmsg_gpio_channel_probe(struct rpmsg_device *rpdev) {
> > + struct device *dev = &rpdev->dev;
> > + struct rpdev_drvdata *drvdata;
> > + struct device_node *np;
> > + int ret = -ENODEV;
> > +
> > + if (!dev->of_node) {
> > + np = rpmsg_get_channel_ofnode(rpdev, rpdev->id.name);
> > + if (np) {
> > + dev->of_node = np;
> > + set_primary_fwnode(dev, of_fwnode_handle(np));
> > + }
> > + return -EPROBE_DEFER;
>
>
> I know this was asked in the v10 version also. But I don't think the answer is
> sufficient. Should we not continue the intialization of drvdata etc if np != 0? Why
> return a deferred probe, and let the kernel come back to it again to do the same
> stuff with extra latency?
>
> We could just do:
> if (!np) return -EPROBE_DEFER;
> else {everything_else};
>

After configuring dev->of_node, it would be better to restart the driver probe process.
This ensures that all required resources, such as pinctrl, clocks, and power domains, are
properly set up if they are specified in the device node, before the probe function is invoked.

Thanks,
Shenwei

> > + }
> > +
> > + drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
> > + if (!drvdata)
> > + return -ENOMEM;
> > +
> > + drvdata->rproc_name = rpmsg_get_rproc_node_name(rpdev);
> > + dev_set_drvdata(dev, drvdata);
> > +
> > + for_each_child_of_node_scoped(dev->of_node, child) {
> > + if (!of_device_is_available(child))
> > + continue;
> > +
> > + if (!of_match_node(dev->driver->of_match_table, child))
> > + continue;
> > +
> > + ret = rpmsg_gpiochip_register(rpdev, child);
> > + if (ret < 0)
> > + break;
>
>
> Why break here? If one port initialization fails, it shouldn't impact the other port
> right? We should just log this and store the appropriate value in ret.
>
> Thanks for your time,
> Beleswar
>
> > + }
> > +
> > + return ret;
> > +}
> > +
> > +static const struct of_device_id rpmsg_gpio_dt_ids[] = {
> > + { .compatible = "rpmsg-gpio" },
> > + { /* sentinel */ }
> > +};
> > +
> > +static struct rpmsg_device_id rpmsg_gpio_channel_id_table[] = {
> > + { .name = "rpmsg-io" },
> > + { },
> > +};
> > +MODULE_DEVICE_TABLE(rpmsg, rpmsg_gpio_channel_id_table);
> > +
> > +static struct rpmsg_driver rpmsg_gpio_channel_client = {
> > + .callback = rpmsg_gpio_channel_callback,
> > + .id_table = rpmsg_gpio_channel_id_table,
> > + .probe = rpmsg_gpio_channel_probe,
> > + .drv = {
> > + .name = KBUILD_MODNAME,
> > + .of_match_table = rpmsg_gpio_dt_ids,
> > + },
> > +};
> > +module_rpmsg_driver(rpmsg_gpio_channel_client);
> > +
> > +MODULE_AUTHOR("Shenwei Wang <shenwei.wang@nxp.com>");
> > +MODULE_DESCRIPTION("generic rpmsg gpio driver");
> > +MODULE_LICENSE("GPL");