Resources modeled as power domains in linux kenrel
can  be used to warm the SoC(eg. mx power domain on sdm845).
To support this feature, introduce a generic power domain
warming device driver that can be plugged into the thermal framework
(The thermal framework itself requires further modifiction to
support a warming device in place of a cooling device.
Those extensions are not introduced in this patch series).

Signed-off-by: Thara Gopinath <thara.gopin...@linaro.org>
---
 drivers/thermal/Kconfig              |  10 +++
 drivers/thermal/Makefile             |   2 +
 drivers/thermal/pwr_domain_warming.c | 136 +++++++++++++++++++++++++++++++++++
 include/linux/pwr_domain_warming.h   |  31 ++++++++
 4 files changed, 179 insertions(+)
 create mode 100644 drivers/thermal/pwr_domain_warming.c
 create mode 100644 include/linux/pwr_domain_warming.h

diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index 001a21a..0c5c93e 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -187,6 +187,16 @@ config DEVFREQ_THERMAL
 
          If you want this support, you should say Y here.
 
+config PWR_DOMAIN_WARMING_THERMAL
+       bool "Power Domain based warming device"
+       depends on PM_GENERIC_DOMAINS_OF
+       help
+         This implements the generic power domain based warming
+         mechanism through increasing the performance state of
+         a power domain.
+
+         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 74a37c7..382c64a 100644
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -27,6 +27,8 @@ thermal_sys-$(CONFIG_CLOCK_THERMAL)   += clock_cooling.o
 # devfreq cooling
 thermal_sys-$(CONFIG_DEVFREQ_THERMAL) += devfreq_cooling.o
 
+thermal_sys-$(CONFIG_PWR_DOMAIN_WARMING_THERMAL)       += pwr_domain_warming.o
+
 # platform thermal drivers
 obj-y                          += broadcom/
 obj-$(CONFIG_THERMAL_MMIO)             += thermal_mmio.o
diff --git a/drivers/thermal/pwr_domain_warming.c 
b/drivers/thermal/pwr_domain_warming.c
new file mode 100644
index 0000000..60fae3e
--- /dev/null
+++ b/drivers/thermal/pwr_domain_warming.c
@@ -0,0 +1,136 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019, Linaro Ltd
+ */
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/module.h>
+#include <linux/pm_runtime.h>
+#include <linux/slab.h>
+#include <linux/pwr_domain_warming.h>
+
+struct pd_warming_device {
+       struct thermal_cooling_device *cdev;
+       struct generic_pm_domain *gpd;
+       struct device *dev;
+       int max_state;
+       int cur_state;
+       bool runtime_resumed;
+};
+
+static int pd_wdev_get_max_state(struct thermal_cooling_device *cdev,
+                                unsigned long *state)
+{
+       struct pd_warming_device *pd_wdev = cdev->devdata;
+
+       *state = pd_wdev->max_state;
+       return 0;
+}
+
+static int pd_wdev_get_cur_state(struct thermal_cooling_device *cdev,
+                                unsigned long *state)
+{
+       struct pd_warming_device *pd_wdev = cdev->devdata;
+
+       *state = dev_pm_genpd_get_performance_state(pd_wdev->dev);
+
+       return 0;
+}
+
+static int pd_wdev_set_cur_state(struct thermal_cooling_device *cdev,
+                                unsigned long state)
+{
+       struct pd_warming_device *pd_wdev = cdev->devdata;
+       struct device *dev = pd_wdev->dev;
+       int ret;
+
+       ret = dev_pm_genpd_set_performance_state(dev, state);
+
+       if (ret)
+               return ret;
+
+       if (state && !pd_wdev->runtime_resumed) {
+               ret = pm_runtime_get_sync(dev);
+               pd_wdev->runtime_resumed = true;
+       } else if (!state && pd_wdev->runtime_resumed) {
+               ret = pm_runtime_put(dev);
+               pd_wdev->runtime_resumed = false;
+       }
+
+       return ret;
+}
+
+static int pd_wdev_late_init(struct thermal_cooling_device *cdev)
+{
+       struct pd_warming_device *pd_wdev = cdev->devdata;
+       struct device *dev = &cdev->device;
+       int state_count, ret;
+
+       ret = pm_genpd_add_device(pd_wdev->gpd, dev);
+
+       if (ret)
+               return ret;
+
+       state_count = dev_pm_genpd_performance_state_count(dev);
+       if (state_count < 0)
+               return state_count;
+
+       pm_runtime_enable(dev);
+
+       pd_wdev->dev = dev;
+       pd_wdev->max_state = state_count - 1;
+
+       return 0;
+}
+
+static struct thermal_cooling_device_ops pd_warming_device_ops = {
+       .late_init      = pd_wdev_late_init,
+       .get_max_state  = pd_wdev_get_max_state,
+       .get_cur_state  = pd_wdev_get_cur_state,
+       .set_cur_state  = pd_wdev_set_cur_state,
+};
+
+struct thermal_cooling_device *
+pwr_domain_warming_register(struct device_node *node,
+                           struct generic_pm_domain *gpd)
+{
+       struct pd_warming_device *pd_wdev;
+
+       pd_wdev = kzalloc(sizeof(*pd_wdev), GFP_KERNEL);
+       if (!pd_wdev)
+               return ERR_PTR(-ENOMEM);
+
+       pd_wdev->runtime_resumed = false;
+       pd_wdev->gpd = gpd;
+
+       pd_wdev->cdev = thermal_of_cooling_device_register
+                                       (node, gpd->name, pd_wdev,
+                                        &pd_warming_device_ops);
+       if (IS_ERR(pd_wdev->cdev)) {
+               pr_err("unable to register %s cooling device\n", gpd->name);
+               if (pd_wdev->dev)
+                       pm_runtime_disable(pd_wdev->dev);
+       }
+
+       return pd_wdev->cdev;
+}
+EXPORT_SYMBOL_GPL(pwr_domain_warming_register);
+
+void pwr_domain_warming_unregister(struct thermal_cooling_device *cdev)
+{
+       struct pd_warming_device *pd_wdev = cdev->devdata;
+       struct device *dev = pd_wdev->dev;
+
+       if (pd_wdev->runtime_resumed) {
+               dev_pm_genpd_set_performance_state(dev, 0);
+               pm_runtime_put(dev);
+               pd_wdev->runtime_resumed = false;
+       }
+       pm_runtime_disable(pd_wdev->dev);
+       thermal_cooling_device_unregister(cdev);
+       kfree(pd_wdev);
+}
+EXPORT_SYMBOL_GPL(pwr_domain_warming_unregister);
diff --git a/include/linux/pwr_domain_warming.h 
b/include/linux/pwr_domain_warming.h
new file mode 100644
index 0000000..ed9942b
--- /dev/null
+++ b/include/linux/pwr_domain_warming.h
@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019, Linaro Ltd.
+ */
+#ifndef __PWR_DOMAIN_WARMING_H__
+#define __PWR_DOMAIN_WARMING_H__
+
+#include <linux/pm_domain.h>
+#include <linux/thermal.h>
+
+#ifdef CONFIG_PWR_DOMAIN_WARMING_THERMAL
+struct thermal_cooling_device *
+pwr_domain_warming_register(struct device_node *node,
+                           struct generic_pm_domain *gpd);
+
+void pwr_domain_warming_unregister(struct thermal_cooling_device *cdev);
+
+#else
+static inline struct thermal_cooling_device *
+pwr_domain_warming_register(struct device_node *node,
+                           struct generic_pm_domain *gpd)
+{
+       return ERR_PTR(-ENOSYS);
+}
+
+static inline void
+pwr_domain_warming_unregister(struct thermal_cooling_device *cdev)
+{
+}
+#endif /* CONFIG_PWR_DOMAIN_WARMING_THERMAL */
+#endif /* __PWR_DOMAIN_WARMING_H__ */
-- 
2.1.4

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