Re: [PATCH v1 1/8] thermal: Add Remote Proc cooling driver
From: Gaurav Kohli
Date: Thu Jan 29 2026 - 00:40:25 EST
On 1/8/2026 5:29 PM, Zhongqiu Han wrote:
On 12/23/2025 8:32 PM, Gaurav Kohli wrote:
Add a new generic driver for thermal cooling devices that control
remote processors (modem, DSP, etc.) through various communication
channels.
This driver provides an abstraction layer between the thermal
subsystem and vendor-specific remote processor communication
mechanisms.
Suggested-by: Amit Kucheria <amit.kucheria@xxxxxxxxxxxxxxxx>
Signed-off-by: Gaurav Kohli <gaurav.kohli@xxxxxxxxxxxxxxxx>
---
MAINTAINERS | 8 ++
drivers/thermal/Kconfig | 11 ++
drivers/thermal/Makefile | 2 +
drivers/thermal/remoteproc_cooling.c | 154 +++++++++++++++++++++++++++
include/linux/remoteproc_cooling.h | 52 +++++++++
5 files changed, 227 insertions(+)
create mode 100644 drivers/thermal/remoteproc_cooling.c
create mode 100644 include/linux/remoteproc_cooling.h
diff --git a/MAINTAINERS b/MAINTAINERS
index 679e5f11e672..c1ba87315cdf 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -25935,6 +25935,14 @@ F: drivers/thermal/cpufreq_cooling.c
F: drivers/thermal/cpuidle_cooling.c
F: include/linux/cpu_cooling.h
+THERMAL/REMOTEPROC_COOLING
+M: Gaurav Kohli <gaurav.kohli@xxxxxxxxxxxxxxxx>
+L: linux-pm@xxxxxxxxxxxxxxx
+S: Supported
+F: drivers/thermal/remoteproc_cooling.c
+F: include/linux/remoteproc_cooling.h
+
+
THERMAL/POWER_ALLOCATOR
M: Lukasz Luba <lukasz.luba@xxxxxxx>
L: linux-pm@xxxxxxxxxxxxxxx
diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index b10080d61860..31e92be34387 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -229,6 +229,17 @@ config PCIE_THERMAL
If you want this support, you should say Y here.
+
+config REMOTEPROC_THERMAL
+ bool "Remote processor cooling support"
Hi Gaurav,
May I know any depends here?
Thanks for review.
Apologies for the late reply, this was missed on my end.
This does not require a dependency, as error check is there for cooling registration api.
+ helpIt's better to have a document to explain member?
+ This implements a generic cooling mechanism for remote processors
+ (modem, DSP, etc.) that allows vendor-specific implementations to
+ register thermal cooling devices and provide callbacks for thermal
+ mitigation.
+
+ If you want this support, you should say Y here.
+
config THERMAL_EMULATION
bool "Thermal emulation mode support"
help
diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
index bb21e7ea7fc6..ae747dde54fe 100644
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -34,6 +34,8 @@ thermal_sys-$(CONFIG_DEVFREQ_THERMAL) += devfreq_cooling.o
thermal_sys-$(CONFIG_PCIE_THERMAL) += pcie_cooling.o
+thermal_sys-$(CONFIG_REMOTEPROC_THERMAL) += remoteproc_cooling.o
+
obj-$(CONFIG_K3_THERMAL) += k3_bandgap.o k3_j72xx_bandgap.o
# platform thermal drivers
obj-y += broadcom/
diff --git a/drivers/thermal/remoteproc_cooling.c b/drivers/thermal/remoteproc_cooling.c
new file mode 100644
index 000000000000..a1f948cbde0f
--- /dev/null
+++ b/drivers/thermal/remoteproc_cooling.c
@@ -0,0 +1,154 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Remote Processor Cooling Device
+ *
+ * Copyright (c) 2025, Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <linux/thermal.h>
+
+#define REMOTEPROC_PREFIX "rproc_"
+
+struct remoteproc_cooling_ops {
+ int (*get_max_level)(void *devdata, unsigned long *level);
+ int (*get_cur_level)(void *devdata, unsigned long *level);
+ int (*set_cur_level)(void *devdata, unsigned long level);
+};
And may I know why double define here(another is in .h file)? should it
include .h file remoteproc_cooling.h ?
Sure, i will add comment for each callback and will fix this double definition.
+
+/**
+ * struct remoteproc_cdev - Remote processor cooling device
+ * @cdev: Thermal cooling device handle
+ * @ops: Vendor-specific operation callbacks
+ * @devdata: Private data for vendor implementation
+ * @np: Device tree node associated with this cooling device
+ * @lock: Mutex to protect cooling device operations
+ */
+struct remoteproc_cdev {
+ struct thermal_cooling_device *cdev;
+ const struct remoteproc_cooling_ops *ops;
+ void *devdata;
+ struct device_node *np;
+ struct mutex lock;
+};
+
+
+/* Thermal cooling device callbacks */
+
+static int remoteproc_get_max_state(struct thermal_cooling_device *cdev,
+ unsigned long *state)
+{
+ struct remoteproc_cdev *rproc_cdev = cdev->devdata;
+ int ret;
+
+ if (!rproc_cdev || !rproc_cdev->ops)
+ return -EINVAL;
+
+ mutex_lock(&rproc_cdev->lock);
+ ret = rproc_cdev->ops->get_max_level(rproc_cdev->devdata, state);
+ mutex_unlock(&rproc_cdev->lock);
+
+ return ret;
+}
+
+static int remoteproc_get_cur_state(struct thermal_cooling_device *cdev,
+ unsigned long *state)
+{
+ struct remoteproc_cdev *rproc_cdev = cdev->devdata;
+ int ret;
+
+ if (!rproc_cdev || !rproc_cdev->ops)
+ return -EINVAL;
+
+ mutex_lock(&rproc_cdev->lock);
+ ret = rproc_cdev->ops->get_cur_level(rproc_cdev->devdata, state);
+ mutex_unlock(&rproc_cdev->lock);
+
+ return ret;
+}
+
+static int remoteproc_set_cur_state(struct thermal_cooling_device *cdev,
+ unsigned long state)
+{
+ struct remoteproc_cdev *rproc_cdev = cdev->devdata;
+ int ret;
+
+ if (!rproc_cdev || !rproc_cdev->ops)
+ return -EINVAL;
+
+ mutex_lock(&rproc_cdev->lock);
+ ret = rproc_cdev->ops->set_cur_level(rproc_cdev->devdata, state);
+ mutex_unlock(&rproc_cdev->lock);
+
+ return ret;
+}
+
+static const struct thermal_cooling_device_ops remoteproc_cooling_ops = {
+ .get_max_state = remoteproc_get_max_state,
+ .get_cur_state = remoteproc_get_cur_state,
+ .set_cur_state = remoteproc_set_cur_state,
+};
+
+struct remoteproc_cdev *
+remoteproc_cooling_register(struct device_node *np,
+ const char *name, const struct remoteproc_cooling_ops *ops,
+ void *devdata)
+{
+ struct remoteproc_cdev *rproc_cdev;
+ struct thermal_cooling_device *cdev;
+ int ret;
+
+ if (!name || !ops) {
+ return ERR_PTR(-EINVAL);
+ }
+
May I know which ops callbacks are required and which are optional?
If the callback is optional, should we check for null before calling it?
Actually all are mandatory for cooling api, will put null check for all to be on safer side.
+ rproc_cdev = kzalloc(sizeof(*rproc_cdev), GFP_KERNEL);
+ if (!rproc_cdev)
+ return ERR_PTR(-ENOMEM);
+
+ rproc_cdev->ops = ops;
+ rproc_cdev->devdata = devdata;
+ rproc_cdev->np = np;
+ mutex_init(&rproc_cdev->lock);
+
+ char *rproc_name __free(kfree) =
+ kasprintf(GFP_KERNEL, REMOTEPROC_PREFIX "%s", name);
It should have a NULL check when alloc memory.
Thanks for pointing this, will update this.
+ /* Register with thermal framework */
+ if (np) {
+ cdev = thermal_of_cooling_device_register(np, rproc_name, rproc_cdev,
+ &remoteproc_cooling_ops);
+ }
+
+ if (IS_ERR(cdev)) {
+ ret = PTR_ERR(cdev);
+ goto free_rproc_cdev;
+ }
+
+ rproc_cdev->cdev = cdev;
+
+ return rproc_cdev;
+
+free_rproc_cdev:
+ kfree(rproc_cdev);
+ return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(remoteproc_cooling_register);
+
+void remoteproc_cooling_unregister(struct remoteproc_cdev *rproc_cdev)
+{
+ if (!rproc_cdev)
+ return;
+
+ thermal_cooling_device_unregister(rproc_cdev->cdev);
+ mutex_destroy(&rproc_cdev->lock);
+ kfree(rproc_cdev);
+}
+EXPORT_SYMBOL_GPL(remoteproc_cooling_unregister);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Remote Processor Cooling Device");
diff --git a/include/linux/remoteproc_cooling.h b/include/linux/remoteproc_cooling.h
new file mode 100644
index 000000000000..ef94019d220d
--- /dev/null
+++ b/include/linux/remoteproc_cooling.h
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Remote Processor Cooling Device
+ *
+ * Copyright (c) 2025, Qualcomm Innovation Center
+ */
+
+#ifndef __REMOTEPROC_COOLING_H__
+#define __REMOTEPROC_COOLING_H__
+
+#include <linux/thermal.h>
+
+struct device;
+struct device_node;
+
+struct remoteproc_cooling_ops {
+ int (*get_max_level)(void *devdata, unsigned long *level);
+ int (*get_cur_level)(void *devdata, unsigned long *level);
+ int (*set_cur_level)(void *devdata, unsigned long level);
+};
+
+struct remoteproc_cdev;
+
+#ifdef CONFIG_REMOTEPROC_THERMAL
+
+struct remoteproc_cdev *
+remoteproc_cooling_register(struct device_node *np,
+ const char *name,
+ const struct remoteproc_cooling_ops *ops,
+ void *devdata);
+
+void remoteproc_cooling_unregister(struct remoteproc_cdev *rproc_cdev);
+
+#else /* !CONFIG_REMOTEPROC_THERMAL */
+
+static inline struct remoteproc_cdev *
+remoteproc_cooling_register(struct device_node *np,
+ const char *name,
+ const struct remoteproc_cooling_ops *ops,
+ void *devdata)
+{
+ return ERR_PTR(-EINVAL);
+}
+
+static inline void
+remoteproc_cooling_unregister(struct remoteproc_cdev *rproc_cdev)
+{
+}
+
+#endif /* CONFIG_REMOTEPROC_THERMAL */
+
+#endif /* __REMOTEPROC_COOLING_H__ */