On Tue, Feb 24, 2026 at 12:38:57AM +0530, Ekansh Gupta wrote:
> Extend the Qualcomm DSP accelerator (QDA) driver with an RPMsg-based
> transport used to discover and manage DSP instances.
>
> This patch introduces:
>
> - A core qda_dev structure with basic device state (rpmsg device,
> device pointer, lock, removal flag, DSP name).
> - Logging helpers that integrate with dev_* when a device is available
> and fall back to pr_* otherwise.
> - An RPMsg client driver that binds to the Qualcomm FastRPC service and
> allocates a qda_dev instance using devm_kzalloc().
> - Basic device initialization and teardown paths wired into the module
> init/exit.
>
> The RPMsg driver currently sets the DSP name from a "label" property in
> the device tree, which will be used by subsequent patches to distinguish
> between different DSP domains (e.g. ADSP, CDSP).
>
> Signed-off-by: Ekansh Gupta <[email protected]>
> ---
> drivers/accel/qda/Kconfig | 1 +
> drivers/accel/qda/Makefile | 4 +-
> drivers/accel/qda/qda_drv.c | 41 ++++++++++++++-
> drivers/accel/qda/qda_drv.h | 91 ++++++++++++++++++++++++++++++++
> drivers/accel/qda/qda_rpmsg.c | 119
> ++++++++++++++++++++++++++++++++++++++++++
> drivers/accel/qda/qda_rpmsg.h | 17 ++++++
> 6 files changed, 270 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/accel/qda/Kconfig b/drivers/accel/qda/Kconfig
> index 3c78ff6189e0..484d21ff1b55 100644
> --- a/drivers/accel/qda/Kconfig
> +++ b/drivers/accel/qda/Kconfig
> @@ -7,6 +7,7 @@ config DRM_ACCEL_QDA
> tristate "Qualcomm DSP accelerator"
> depends on DRM_ACCEL
> depends on ARCH_QCOM || COMPILE_TEST
> + depends on RPMSG
> help
> Enables the DRM-based accelerator driver for Qualcomm's Hexagon DSPs.
> This driver provides a standardized interface for offloading
> computational
> diff --git a/drivers/accel/qda/Makefile b/drivers/accel/qda/Makefile
> index 573711af1d28..e7f23182589b 100644
> --- a/drivers/accel/qda/Makefile
> +++ b/drivers/accel/qda/Makefile
> @@ -5,4 +5,6 @@
>
> obj-$(CONFIG_DRM_ACCEL_QDA) := qda.o
>
> -qda-y := qda_drv.o
> +qda-y := \
> + qda_drv.o \
Squash these parts into the previous patch.
> + qda_rpmsg.o \
> diff --git a/drivers/accel/qda/qda_drv.c b/drivers/accel/qda/qda_drv.c
> index 18b0d3fb1598..389c66a9ad4f 100644
> --- a/drivers/accel/qda/qda_drv.c
> +++ b/drivers/accel/qda/qda_drv.c
> @@ -2,16 +2,53 @@
> // Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
> #include <linux/module.h>
> #include <linux/kernel.h>
> +#include <linux/atomic.h>
> +#include "qda_drv.h"
> +#include "qda_rpmsg.h"
> +
> +static void cleanup_device_resources(struct qda_dev *qdev)
> +{
> + mutex_destroy(&qdev->lock);
> +}
> +
> +void qda_deinit_device(struct qda_dev *qdev)
> +{
> + cleanup_device_resources(qdev);
> +}
> +
> +/* Initialize device resources */
> +static void init_device_resources(struct qda_dev *qdev)
> +{
> + qda_dbg(qdev, "Initializing device resources\n");
> +
> + mutex_init(&qdev->lock);
> + atomic_set(&qdev->removing, 0);
> +}
> +
> +int qda_init_device(struct qda_dev *qdev)
> +{
> + init_device_resources(qdev);
> +
> + qda_dbg(qdev, "QDA device initialized successfully\n");
> + return 0;
> +}
>
> static int __init qda_core_init(void)
> {
> - pr_info("QDA: driver initialization complete\n");
> + int ret;
> +
> + ret = qda_rpmsg_register();
> + if (ret)
> + return ret;
> +
> + qda_info(NULL, "QDA driver initialization complete\n");
> return 0;
> }
>
> static void __exit qda_core_exit(void)
> {
> - pr_info("QDA: driver exit complete\n");
> + qda_rpmsg_unregister();
> + qda_info(NULL, "QDA driver exit complete\n");
> }
>
> module_init(qda_core_init);
> diff --git a/drivers/accel/qda/qda_drv.h b/drivers/accel/qda/qda_drv.h
> new file mode 100644
> index 000000000000..bec2d31ca1bb
> --- /dev/null
> +++ b/drivers/accel/qda/qda_drv.h
> @@ -0,0 +1,91 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
> + */
> +
> +#ifndef __QDA_DRV_H__
> +#define __QDA_DRV_H__
> +
> +#include <linux/device.h>
> +#include <linux/mutex.h>
> +#include <linux/rpmsg.h>
> +#include <linux/xarray.h>
> +
> +/* Driver identification */
> +#define DRIVER_NAME "qda"
> +
> +/* struct qda_dev - Main device structure for QDA driver */
> +struct qda_dev {
> + /* RPMsg device for communication with remote processor */
> + struct rpmsg_device *rpdev;
> + /* Underlying device structure */
> + struct device *dev;
> + /* Mutex protecting device state */
> + struct mutex lock;
Which parts of the state?
> + /* Flag indicating device removal in progress */
> + atomic_t removing;
Why do you need it if we have dev->unplugged and drm_dev_enter() /
drm_dev_exit()?
> + /* Name of the DSP (e.g., "cdsp", "adsp") */
> + char dsp_name[16];
Please replace with the pointers to the static array.
> +};
> +
> +/**
> + * qda_get_log_device - Get appropriate device for logging
> + * @qdev: QDA device structure
> + *
> + * Returns the most appropriate device structure for logging messages.
> + * Prefers qdev->dev, or returns NULL if the device is being removed
> + * or invalid.
> + */
> +static inline struct device *qda_get_log_device(struct qda_dev *qdev)
> +{
> + if (!qdev || atomic_read(&qdev->removing))
> + return NULL;
> +
> + if (qdev->dev)
> + return qdev->dev;
> +
> + return NULL;
> +}
> +
> +/*
> + * Logging macros
> + *
> + * These macros provide consistent logging across the driver with automatic
> + * function name inclusion. They use dev_* functions when a device is
> available,
> + * falling back to pr_* functions otherwise.
> + */
> +
> +/* Error logging - always logs and tracks errors */
> +#define qda_err(qdev, fmt, ...) do { \
> + struct device *__dev = qda_get_log_device(qdev); \
> + if (__dev) \
> + dev_err(__dev, "[%s] " fmt, __func__, ##__VA_ARGS__); \
> + else \
> + pr_err(DRIVER_NAME ": [%s] " fmt, __func__, ##__VA_ARGS__); \
What /why? You are under drm, so you can use drm_* helpers instead.
> +} while (0)
> +
> +/* Info logging - always logs, can be filtered via loglevel */
> +#define qda_info(qdev, fmt, ...) do { \
> + struct device *__dev = qda_get_log_device(qdev); \
> + if (__dev) \
> + dev_info(__dev, "[%s] " fmt, __func__, ##__VA_ARGS__); \
> + else \
> + pr_info(DRIVER_NAME ": [%s] " fmt, __func__, ##__VA_ARGS__); \
> +} while (0)
> +
> +/* Debug logging - controlled via dynamic debug (CONFIG_DYNAMIC_DEBUG) */
> +#define qda_dbg(qdev, fmt, ...) do { \
> + struct device *__dev = qda_get_log_device(qdev); \
> + if (__dev) \
> + dev_dbg(__dev, "[%s] " fmt, __func__, ##__VA_ARGS__); \
> + else \
> + pr_debug(DRIVER_NAME ": [%s] " fmt, __func__, ##__VA_ARGS__); \
> +} while (0)
> +
> +/*
> + * Core device management functions
> + */
> +int qda_init_device(struct qda_dev *qdev);
> +void qda_deinit_device(struct qda_dev *qdev);
> +
> +#endif /* __QDA_DRV_H__ */
> diff --git a/drivers/accel/qda/qda_rpmsg.c b/drivers/accel/qda/qda_rpmsg.c
> new file mode 100644
> index 000000000000..a8b24a99ca13
> --- /dev/null
> +++ b/drivers/accel/qda/qda_rpmsg.c
> @@ -0,0 +1,119 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +// Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
> +#include <linux/module.h>
> +#include <linux/rpmsg.h>
> +#include <linux/of_platform.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include "qda_drv.h"
> +#include "qda_rpmsg.h"
> +
> +static int qda_rpmsg_init(struct qda_dev *qdev)
> +{
> + dev_set_drvdata(&qdev->rpdev->dev, qdev);
> + return 0;
> +}
> +
> +/* Utility function to allocate and initialize qda_dev */
> +static struct qda_dev *alloc_and_init_qdev(struct rpmsg_device *rpdev)
> +{
> + struct qda_dev *qdev;
> +
> + qdev = devm_kzalloc(&rpdev->dev, sizeof(*qdev), GFP_KERNEL);
> + if (!qdev)
> + return ERR_PTR(-ENOMEM);
> +
> + qdev->dev = &rpdev->dev;
> + qdev->rpdev = rpdev;
> +
> + qda_dbg(qdev, "Allocated and initialized qda_dev\n");
> + return qdev;
> +}
> +
> +static int qda_rpmsg_cb(struct rpmsg_device *rpdev, void *data, int len,
> void *priv, u32 src)
> +{
> + /* Dummy function for rpmsg driver */
> + return 0;
> +}
> +
> +static void qda_rpmsg_remove(struct rpmsg_device *rpdev)
> +{
> + struct qda_dev *qdev = dev_get_drvdata(&rpdev->dev);
> +
> + qda_info(qdev, "Removing RPMsg device\n");
> +
> + atomic_set(&qdev->removing, 1);
> +
> + mutex_lock(&qdev->lock);
> + qdev->rpdev = NULL;
> + mutex_unlock(&qdev->lock);
> +
> + qda_deinit_device(qdev);
> +
> + qda_info(qdev, "RPMsg device removed\n");
> +}
> +
> +static int qda_rpmsg_probe(struct rpmsg_device *rpdev)
> +{
> + struct qda_dev *qdev;
> + int ret;
> + const char *label;
> +
> + qda_dbg(NULL, "QDA RPMsg probe starting\n");
> +
> + qdev = alloc_and_init_qdev(rpdev);
> + if (IS_ERR(qdev))
> + return PTR_ERR(qdev);
> +
> + ret = of_property_read_string(rpdev->dev.of_node, "label", &label);
> + if (!ret) {
> + strscpy(qdev->dsp_name, label, sizeof(qdev->dsp_name));
> + } else {
> + qda_info(qdev, "QDA DSP label not found in DT\n");
> + return ret;
> + }
> +
> + ret = qda_rpmsg_init(qdev);
> + if (ret) {
> + qda_err(qdev, "RPMsg init failed: %d\n", ret);
> + return ret;
> + }
> +
> + ret = qda_init_device(qdev);
> + if (ret)
> + return ret;
> +
> + qda_info(qdev, "QDA RPMsg probe completed successfully for %s\n",
> qdev->dsp_name);
> + return 0;
> +}
> +
> +static const struct of_device_id qda_rpmsg_id_table[] = {
> + { .compatible = "qcom,fastrpc" },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, qda_rpmsg_id_table);
> +
> +static struct rpmsg_driver qda_rpmsg_driver = {
> + .probe = qda_rpmsg_probe,
> + .remove = qda_rpmsg_remove,
> + .callback = qda_rpmsg_cb,
> + .drv = {
> + .name = "qcom,fastrpc",
> + .of_match_table = qda_rpmsg_id_table,
> + },
> +};
> +
> +int qda_rpmsg_register(void)
> +{
> + int ret = register_rpmsg_driver(&qda_rpmsg_driver);
> +
> + if (ret)
> + qda_err(NULL, "Failed to register RPMsg driver: %d\n", ret);
> +
> + return ret;
> +}
> +
> +void qda_rpmsg_unregister(void)
> +{
> + unregister_rpmsg_driver(&qda_rpmsg_driver);
> +}
> diff --git a/drivers/accel/qda/qda_rpmsg.h b/drivers/accel/qda/qda_rpmsg.h
> new file mode 100644
> index 000000000000..348827bff255
> --- /dev/null
> +++ b/drivers/accel/qda/qda_rpmsg.h
> @@ -0,0 +1,17 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
> + */
> +
> +#ifndef __QDA_RPMSG_H__
> +#define __QDA_RPMSG_H__
> +
> +#include "qda_drv.h"
> +
> +/*
> + * Transport layer registration
> + */
> +int qda_rpmsg_register(void);
> +void qda_rpmsg_unregister(void);
> +
> +#endif /* __QDA_RPMSG_H__ */
>
> --
> 2.34.1
>
--
With best wishes
Dmitry
