[RFC PATCH 01/17] hw/misc: Introduce the temperature sensor interface

[Philippe Mathieu-Daudé]

Introduce an interface to set and get temperature from devices.

A device can have multiple temperature sensors.
Each sensor might have a custom name.

Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
---
 include/hw/misc/temp-sensor.h | 69 +++++++++++++++++++++++++++++++++++
 hw/misc/temp-sensor.c         | 25 +++++++++++++
 MAINTAINERS                   |  6 +++
 hw/misc/Makefile.objs         |  1 +
 4 files changed, 101 insertions(+)
 create mode 100644 include/hw/misc/temp-sensor.h
 create mode 100644 hw/misc/temp-sensor.c

diff --git a/include/hw/misc/temp-sensor.h b/include/hw/misc/temp-sensor.h
new file mode 100644
index 0000000000..3067b1dd2e
--- /dev/null
+++ b/include/hw/misc/temp-sensor.h
@@ -0,0 +1,69 @@
+/*
+ * Generic interface for temperature sensors
+ *
+ * Copyright (c) 2020 Philippe Mathieu-Daudé
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#ifndef HW_MISC_TEMP_SENSOR_H
+#define HW_MISC_TEMP_SENSOR_H
+
+#include "qom/object.h"
+
+#define TYPE_TEMPSENSOR_INTERFACE "temp-sensor-interface"
+#define TEMPSENSOR_INTERFACE(obj) \
+    INTERFACE_CHECK(TempSensor, (obj), TYPE_TEMPSENSOR_INTERFACE)
+#define TEMPSENSOR_INTERFACE_CLASS(class) \
+    OBJECT_CLASS_CHECK(TempSensorClass, (class), TYPE_TEMPSENSOR_INTERFACE)
+#define TEMPSENSOR_INTERFACE_GET_CLASS(class) \
+    OBJECT_GET_CLASS(TempSensorClass, (class), TYPE_TEMPSENSOR_INTERFACE)
+
+typedef struct TempSensor TempSensor;
+
+typedef struct TempSensorClass {
+    /* <private> */
+    InterfaceClass parent;
+    /* <public> */
+
+    /** Number of temperature sensors */
+    size_t sensor_count;
+
+    /**
+     * get_name:
+     * @obj: opaque pointer to Object
+     * @sensor_id: sensor index
+     *
+     * Returns: name of a temperature sensor.
+     */
+    const char *(*get_name)(TempSensor *obj, unsigned sensor_id);
+
+    /**
+     * set_temperature:
+     * @obj: opaque pointer to Object
+     * @sensor_id: sensor index
+     * @temp_C: sensor temperature, in degree Celsius
+     * @errp: pointer to a NULL-initialized error object
+     *
+     * Set a sensor temperature.
+     *
+     * If an error occurs @errp will contain the details
+     * (likely temperature out of range).
+     */
+    void (*set_temperature)(TempSensor *obj,
+                            unsigned sensor_id, float temp_C, Error **errp);
+
+    /**
+     * get_temperature:
+     * @obj: opaque pointer to Object
+     * @sensor_id: sensor index
+     *
+     * Get a sensor temperature.
+     *
+     * Returns: sensor temperature in °C.
+     */
+    float (*get_temperature)(TempSensor *obj, unsigned sensor_id);
+} TempSensorClass;
+
+#endif /* HW_MISC_TEMP_SENSOR_H */
diff --git a/hw/misc/temp-sensor.c b/hw/misc/temp-sensor.c
new file mode 100644
index 0000000000..b7c1eb2d87
--- /dev/null
+++ b/hw/misc/temp-sensor.c
@@ -0,0 +1,25 @@
+/*
+ * Generic interface for temperature sensors
+ *
+ * Copyright (c) 2020 Philippe Mathieu-Daudé
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "hw/misc/temp-sensor.h"
+
+static TypeInfo tempsensor_interface_type_info = {
+    .name = TYPE_TEMPSENSOR_INTERFACE,
+    .parent = TYPE_INTERFACE,
+    .class_size = sizeof(TempSensorClass),
+};
+
+static void tempsensor_register_types(void)
+{
+    type_register_static(&tempsensor_interface_type_info);
+}
+
+type_init(tempsensor_register_types)
diff --git a/MAINTAINERS b/MAINTAINERS
index 8cbc1fac2b..5559110c56 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1575,6 +1575,12 @@ F: hw/sd/sd*
 F: hw/sd/ssi-sd.c
 F: tests/qtest/sd*
 
+Temperature Sensors
+M: Philippe Mathieu-Daudé <address@hidden>
+S: Odd Fixes
+F: hw/misc/temp-sensor.c
+F: include/hw/misc/temp-sensor.h
+
 USB
 M: Gerd Hoffmann <address@hidden>
 S: Maintained
diff --git a/hw/misc/Makefile.objs b/hw/misc/Makefile.objs
index 68aae2eabb..4f90efb06d 100644
--- a/hw/misc/Makefile.objs
+++ b/hw/misc/Makefile.objs
@@ -90,3 +90,4 @@ common-obj-$(CONFIG_NRF51_SOC) += nrf51_rng.o
 obj-$(CONFIG_MAC_VIA) += mac_via.o
 
 common-obj-$(CONFIG_GRLIB) += grlib_ahb_apb_pnp.o
+common-obj-y += temp-sensor.o
-- 
2.21.1