[PATCH 0/2] Thermal MMIO Driver

[PATCH 0/2] Thermal MMIO Driver

[Talel Shenhar]

This series introduces the generic thermal MMIO driver that will use
memory mapped reads to get the temperature.  Any HW/System that
allows temperature reading by a single memory-mapped reading, be it
register or shared memory, is a potential candidate to work with this
driver.

This driver is most suitable for cases such as the following:
- The entire thermal HW setup is done by another SW entity (e.g.
  bootloader) and all that is left is to read the current temperature from
  a register.
- The thermal HW setup is done via an external CPU (e.g. micro-controller)
  and that CPU has is using shared memory that can be memory-mapped to this
  driver.
- The thermal HW setup and reading is done via CPLD, which exports the
  current temperature to the system via a register.
- The thermal HW is working out-of-the-box and only reports temperature via
  a single register access.



Talel Shenhar (2):
  dt-bindings: thermal: thermal_mmio: Add binding documentation
  thermal: Introduce thermal MMIO

 .../devicetree/bindings/thermal/thermal_mmio.txt   | 173 +++++++++++++++++
 drivers/thermal/Kconfig                            |  11 ++
 drivers/thermal/Makefile                           |   3 +
 drivers/thermal/thermal_mmio.c                     | 214 +++++++++++++++++++++
 4 files changed, 401 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/thermal/thermal_mmio.txt
 create mode 100644 drivers/thermal/thermal_mmio.c

-- 
2.7.4

[PATCH 1/2] dt-bindings: thermal: thermal_mmio: Add binding documentation

[Talel Shenhar]

Add thermal binding documentation for thermal MMIO driver.

Signed-off-by: Talel Shenhar <talel@amazon.com>
---
 .../devicetree/bindings/thermal/thermal_mmio.txt   | 173 +++++++++++++++++++++
 1 file changed, 173 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/thermal/thermal_mmio.txt

diff --git a/Documentation/devicetree/bindings/thermal/thermal_mmio.txt b/Documentation/devicetree/bindings/thermal/thermal_mmio.txt
new file mode 100644
index 0000000..1f4d738
--- /dev/null
+++ b/Documentation/devicetree/bindings/thermal/thermal_mmio.txt
@@ -0,0 +1,173 @@
+Generic Thermal MMIO Driver
+
+The generic thermal driver enables easy connectivity between "simple"
+thermal HW devices to the thermal subsystem. "simple" - thermal HW that
+doesn't need any configuration (such as power reset or clock enable) by a
+driver and only exports the temperature via simple MMIO access, or,
+alternatively, all the configuration is done by other entity (e.g.
+bootloader).
+
+Any system that allows temperature reading via a single memory map read, be
+it register or shared memory, is a potential candidate to work with this
+driver.
+This driver allows manipulations on the read value in order to allow some
+flexibility for the various thermal HW, e.g. sensor-factor which will be
+multiplied by the read value.
+
+This driver is most suitable for cases such as the following:
+- The entire thermal HW setup (e.g. configure the thermal HW to work in
+  continuous mode) is done by another SW entity (e.g. bootloader) and all
+  that is left is to read the current temperature from a register
+- The thermal reading is done by an external CPU (e.g. micro-controller)
+  and that CPU is exporting the reading via a shared memory
+- The thermal HW setup and reading is done via CPLD, which exports the
+  current temperature to the system via a register
+- The thermal HW is working out-of-the-box and only reports temperature via
+  a single register access
+
+Some examples for cases that this driver is not suitable for:
+- Your HW need clock enabling to be done by thermal driver
+- Your HW need some registers configurations in order to start reporting
+  temperatures and it is not doable by other entities (e.g. bootloader)
+- Your HW allows reading of temperatures only between ADCs (or any other
+  timing constrains)
+- In case your HW was configured by a bootloader and it lose the
+  configuration as part of low-power-state and need to be reconfigured.
+  (bootloader configuration typically is not sustained across low power
+  states)
+- In case the reading from the MMIO require any type of locking
+
+So the only operation this driver will do is MMIO read for the temperature.
+In case you are using HW that require some configurations this driver is
+not suitable (you can decide to move all the configuration logic into your
+bootloader and only leave the temperature reading to this driver but this
+is up to you).
+
+An example of a system that uses this driver is the Amazon Nitro SoC in
+which there is the main CPU and micro-controller:
+(1) The micro-controller accesses an SBUS controller to read the thermal
+    sensor from an SBUS slave called Avago Technologies digital
+    Temperature/Voltage Sensor (ip16_SENS_thermvolt25_0)
+(2) Once the micro-controller gathers the temperature it relays it to the
+    main CPU via a Shared Integrated RAM which is MMIO accessible by the CPU
+(3) The thermal_mmio driver that runs on the main CPU will read the
+    temperature via an MMIO access to the Shared RAM
+
++------------------+      +----------------+
+|                  | (3)  |                |
+|     Main CPU     +----->+ Integrated RAM |
+|                  |      |                |
++------------------+      +---------^------+
+                                    |(2)
++-----------------+       +------------------+
+|                 |  (1)  |                  |
+| SBUS controller <-------+ micro-controller |
+|                 |       |                  |
++--------+--------+       +------------------+
+         |
++--------v---------------------+
+|                              |
+|  Avago Technologies digital  |
+|  Temperature/Voltage Sensor  |
+|  (ip16_SENS_thermvolt25_0)   |
+|                              |
++------------------------------+
+
+Required properties:
+- compatible: "thermal-mmio".
+- reg: The physical base address and length of the sensor's registers.
+- #thermal-sensor-cells: Must be 1. See ./thermal.txt for a description.
+
+Optional properties:
+- sensor-width: Width (in bytes) of each consecutive sensor.
+		 Supported: 1, 2, 4.
+		 (Default = 4)
+- sensor-mask: Mask to be applied on the raw read value before any
+	       calculation.
+	       (Default = 0xFFFFFFFF)
+- sensor-factor: Scale value by which to multiple the masked read value
+		 This is a signed 32 bit value.
+		 (Default = 1)
+- sensor-bias: Bias value to be added to the scaled value.
+	       This is a signed 32 bit value.
+	       (Default = 0)
+- sensor-divider: Dividing value by which to divide the calculated value.
+		  Diving will be Integer Division.
+		  This is a unsigned 32 bit value.
+		  (Default = 1)
+
+Conversion formula from HW MMIO read value to millidegrees (Celsius):
+T_millidegrees = (bias + (T_raw & mask)*factor)/divider
+
+Example 1, two thermal devices with one thermal sensor each, that uses only
+the required properties (uses default):
+
+	thermal_d1: thermal_d1 {
+		compatible = "thermal-mmio";
+		reg = <0x0 0x05002860 0x0 0x4>;
+		#thermal-sensor-cells = <0x1>;
+	};
+
+	thermal_d2: thermal_d2 {
+		compatible = "thermal-mmio";
+		reg = <0x0 0x05000730 0x0 0x4>;
+		#thermal-sensor-cells = <0x1>;
+	};
+
+	thermal-zones {
+		thermal_d1_z0 {
+			polling-delay-passive = <250>;
+			polling-delay = <1000>;
+			thermal-sensors = <&thermal_d1 0>;
+			trips {
+				thermal_d1_z0_crit {
+					temperature = <105000>;
+					hysteresis = <2000>;
+					type = "critical";
+				};
+			};
+
+		};
+
+		thermal_d2_z0 {
+			polling-delay-passive = <250>;
+			polling-delay = <1000>;
+			thermal-sensors = <&thermal_d2 0>;
+			trips {
+				thermal_d2_z0_crit {
+					temperature = <105000>;
+					hysteresis = <2000>;
+					type = "critical";
+				};
+			};
+		};
+	};
+
+Example 2, one thermal device with two sensors of 6 bits each each, that
+has a factor of -5, bias of 23 and dividing of 2:
+
+	thermal_d3: thermal_d3 {
+		compatible = "thermal-mmio";
+		reg = <0x0 0x05005700 0x0 0x2>;
+		#thermal-sensor-cells = <0x1>;
+		sensor-width = <1>;
+		sensor-mask = <0x3F>;
+		sensor-factor = <(-5)>;
+		sensor-bias = <23>;
+		sensor-divider = <2>;
+	};
+
+	thermal-zones {
+		thermal_d3 {
+			polling-delay-passive = <250>;
+			polling-delay = <1000>;
+			thermal-sensors = <&thermal_d3 0>;
+			trips {
+				thermal_d3_z0_crit {
+					temperature = <105000>;
+					hysteresis = <2000>;
+					type = "critical";
+				};
+			};
+		};
+	};
-- 
2.7.4

Re: [PATCH 1/2] dt-bindings: thermal: thermal_mmio: Add binding documentation

[Rob Herring]

On Sun, Mar 03, 2019 at 10:49:25AM +0200, Talel Shenhar wrote:
> Add thermal binding documentation for thermal MMIO driver.
> 
> Signed-off-by: Talel Shenhar <talel@amazon.com>
> ---
>  .../devicetree/bindings/thermal/thermal_mmio.txt   | 173 +++++++++++++++++++++
>  1 file changed, 173 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/thermal/thermal_mmio.txt
> 
> diff --git a/Documentation/devicetree/bindings/thermal/thermal_mmio.txt b/Documentation/devicetree/bindings/thermal/thermal_mmio.txt
> new file mode 100644
> index 0000000..1f4d738
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/thermal/thermal_mmio.txt
> @@ -0,0 +1,173 @@
> +Generic Thermal MMIO Driver

Bindings aren't for drivers.

Do h/w specific bindings and map those to a generic driver if you like. 
We simply don't do single register level bindings because that doesn't 
scale and things never turn out to be so generic.

> +
> +The generic thermal driver enables easy connectivity between "simple"
> +thermal HW devices to the thermal subsystem. "simple" - thermal HW that
> +doesn't need any configuration (such as power reset or clock enable) by a
> +driver and only exports the temperature via simple MMIO access, or,
> +alternatively, all the configuration is done by other entity (e.g.
> +bootloader).
> +
> +Any system that allows temperature reading via a single memory map read, be
> +it register or shared memory, is a potential candidate to work with this
> +driver.
> +This driver allows manipulations on the read value in order to allow some
> +flexibility for the various thermal HW, e.g. sensor-factor which will be
> +multiplied by the read value.
> +
> +This driver is most suitable for cases such as the following:
> +- The entire thermal HW setup (e.g. configure the thermal HW to work in
> +  continuous mode) is done by another SW entity (e.g. bootloader) and all
> +  that is left is to read the current temperature from a register
> +- The thermal reading is done by an external CPU (e.g. micro-controller)
> +  and that CPU is exporting the reading via a shared memory
> +- The thermal HW setup and reading is done via CPLD, which exports the
> +  current temperature to the system via a register
> +- The thermal HW is working out-of-the-box and only reports temperature via
> +  a single register access
> +
> +Some examples for cases that this driver is not suitable for:
> +- Your HW need clock enabling to be done by thermal driver

...or avoiding disabling of a clock, regulator, etc.

> +- Your HW need some registers configurations in order to start reporting
> +  temperatures and it is not doable by other entities (e.g. bootloader)
> +- Your HW allows reading of temperatures only between ADCs (or any other
> +  timing constrains)
> +- In case your HW was configured by a bootloader and it lose the
> +  configuration as part of low-power-state and need to be reconfigured.
> +  (bootloader configuration typically is not sustained across low power
> +  states)
> +- In case the reading from the MMIO require any type of locking

Or filtering/averaging of values.

> +
> +So the only operation this driver will do is MMIO read for the temperature.
> +In case you are using HW that require some configurations this driver is
> +not suitable (you can decide to move all the configuration logic into your
> +bootloader and only leave the temperature reading to this driver but this
> +is up to you).
> +
> +An example of a system that uses this driver is the Amazon Nitro SoC in
> +which there is the main CPU and micro-controller:
> +(1) The micro-controller accesses an SBUS controller to read the thermal
> +    sensor from an SBUS slave called Avago Technologies digital
> +    Temperature/Voltage Sensor (ip16_SENS_thermvolt25_0)
> +(2) Once the micro-controller gathers the temperature it relays it to the
> +    main CPU via a Shared Integrated RAM which is MMIO accessible by the CPU
> +(3) The thermal_mmio driver that runs on the main CPU will read the
> +    temperature via an MMIO access to the Shared RAM
> +
> ++------------------+      +----------------+
> +|                  | (3)  |                |
> +|     Main CPU     +----->+ Integrated RAM |
> +|                  |      |                |
> ++------------------+      +---------^------+
> +                                    |(2)
> ++-----------------+       +------------------+
> +|                 |  (1)  |                  |
> +| SBUS controller <-------+ micro-controller |
> +|                 |       |                  |
> ++--------+--------+       +------------------+
> +         |
> ++--------v---------------------+
> +|                              |
> +|  Avago Technologies digital  |
> +|  Temperature/Voltage Sensor  |
> +|  (ip16_SENS_thermvolt25_0)   |
> +|                              |
> ++------------------------------+

Very specific information for a 'generic' binding.

> +
> +Required properties:
> +- compatible: "thermal-mmio".
> +- reg: The physical base address and length of the sensor's registers.
> +- #thermal-sensor-cells: Must be 1. See ./thermal.txt for a description.
> +
> +Optional properties:> +- sensor-width: Width (in bytes) of each consecutive sensor.
> +		 Supported: 1, 2, 4.
> +		 (Default = 4)
> +- sensor-mask: Mask to be applied on the raw read value before any
> +	       calculation.
> +	       (Default = 0xFFFFFFFF)
> +- sensor-factor: Scale value by which to multiple the masked read value
> +		 This is a signed 32 bit value.
> +		 (Default = 1)
> +- sensor-bias: Bias value to be added to the scaled value.
> +	       This is a signed 32 bit value.
> +	       (Default = 0)
> +- sensor-divider: Dividing value by which to divide the calculated value.
> +		  Diving will be Integer Division.
> +		  This is a unsigned 32 bit value.
> +		  (Default = 1)

If you are going to abstract all the h/w access, then get rid of all of 
this and just put Celsius values into the "register".

> +
> +Conversion formula from HW MMIO read value to millidegrees (Celsius):
> +T_millidegrees = (bias + (T_raw & mask)*factor)/divider
> +
> +Example 1, two thermal devices with one thermal sensor each, that uses only
> +the required properties (uses default):
> +
> +	thermal_d1: thermal_d1 {
> +		compatible = "thermal-mmio";
> +		reg = <0x0 0x05002860 0x0 0x4>;
> +		#thermal-sensor-cells = <0x1>;
> +	};
> +
> +	thermal_d2: thermal_d2 {
> +		compatible = "thermal-mmio";
> +		reg = <0x0 0x05000730 0x0 0x4>;
> +		#thermal-sensor-cells = <0x1>;
> +	};
> +
> +	thermal-zones {
> +		thermal_d1_z0 {
> +			polling-delay-passive = <250>;
> +			polling-delay = <1000>;
> +			thermal-sensors = <&thermal_d1 0>;
> +			trips {
> +				thermal_d1_z0_crit {
> +					temperature = <105000>;
> +					hysteresis = <2000>;
> +					type = "critical";
> +				};
> +			};
> +
> +		};
> +
> +		thermal_d2_z0 {
> +			polling-delay-passive = <250>;
> +			polling-delay = <1000>;
> +			thermal-sensors = <&thermal_d2 0>;
> +			trips {
> +				thermal_d2_z0_crit {
> +					temperature = <105000>;
> +					hysteresis = <2000>;
> +					type = "critical";
> +				};
> +			};
> +		};
> +	};
> +
> +Example 2, one thermal device with two sensors of 6 bits each each, that
> +has a factor of -5, bias of 23 and dividing of 2:
> +
> +	thermal_d3: thermal_d3 {
> +		compatible = "thermal-mmio";
> +		reg = <0x0 0x05005700 0x0 0x2>;
> +		#thermal-sensor-cells = <0x1>;
> +		sensor-width = <1>;
> +		sensor-mask = <0x3F>;
> +		sensor-factor = <(-5)>;
> +		sensor-bias = <23>;
> +		sensor-divider = <2>;
> +	};
> +
> +	thermal-zones {
> +		thermal_d3 {
> +			polling-delay-passive = <250>;
> +			polling-delay = <1000>;
> +			thermal-sensors = <&thermal_d3 0>;
> +			trips {
> +				thermal_d3_z0_crit {
> +					temperature = <105000>;
> +					hysteresis = <2000>;
> +					type = "critical";
> +				};
> +			};
> +		};
> +	};
> -- 
> 2.7.4
> 

[PATCH 2/2] thermal: Introduce thermal MMIO

[Talel Shenhar]

This patch introduces a generic thermal driver, which enables easy
connectivity between "simple" thermal HW devices and the thermal
subsystem.

"simple" may be any system that allows temperature reading via a single
memory-mapped read, be it register or shared memory, and that doesn't
require any HW configuration to be done by the driver.
Such "simple" HW is a candidate to work with this driver.

Signed-off-by: Talel Shenhar <talel@amazon.com>
---
 drivers/thermal/Kconfig        |  11 +++
 drivers/thermal/Makefile       |   3 +
 drivers/thermal/thermal_mmio.c | 214 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 228 insertions(+)
 create mode 100644 drivers/thermal/thermal_mmio.c

diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index 1775d44..0033ba2 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -199,6 +199,17 @@ config THERMAL_EMULATION
 	  because userland can easily disable the thermal policy by simply
 	  flooding this sysfs node with low temperature values.
 
+config THERMAL_MMIO
+	bool
+	depends on OF || COMPILE_TEST
+	prompt "mmio thermal driver"
+	help
+	  This option enables the generic thermal MMIO driver that will use
+	  memory-mapped reads to get the temperature.  Any HW/System that
+	  allows temperature reading by a single memory-mapped reading, be it
+	  register or shared memory, is a potential candidate to work with this
+	  driver.
+
 config HISI_THERMAL
 	tristate "Hisilicon thermal driver"
 	depends on ARCH_HISI || COMPILE_TEST
diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
index 82bb50d..beec616 100644
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -27,6 +27,9 @@ thermal_sys-$(CONFIG_CLOCK_THERMAL)	+= clock_cooling.o
 # devfreq cooling
 thermal_sys-$(CONFIG_DEVFREQ_THERMAL) += devfreq_cooling.o
 
+# generic memory mapped thermal driver
+thermal_sys-$(CONFIG_THERMAL_MMIO)	+= thermal_mmio.o
+
 # platform thermal drivers
 obj-y				+= broadcom/
 obj-$(CONFIG_QCOM_SPMI_TEMP_ALARM)	+= qcom-spmi-temp-alarm.o
diff --git a/drivers/thermal/thermal_mmio.c b/drivers/thermal/thermal_mmio.c
new file mode 100644
index 0000000..1119e71
--- /dev/null
+++ b/drivers/thermal/thermal_mmio.c
@@ -0,0 +1,214 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ */
+
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/thermal.h>
+
+#define THERMAL_MMIO_DEFAULT_SENSOR_WIDTH sizeof(u32)
+#define THERMAL_MMIO_DEFAULT_SENSOR_FACTOR 1
+#define THERMAL_MMIO_DEFAULT_SENSOR_BIAS 0
+#define THERMAL_MMIO_DEFAULT_SENSOR_DIVIDER 1
+
+struct thermal_mmio {
+	void __iomem *mmio_base;
+	u32 (*read_mmio)(void __iomem *mmio_base);
+	int width;
+	u32 mask;
+	int factor;
+	int bias;
+	int divider;
+};
+
+static u32 thermal_mmio_readb(void __iomem *mmio_base)
+{
+	return readb(mmio_base);
+}
+
+static u32 thermal_mmio_readw(void __iomem *mmio_base)
+{
+	return readw(mmio_base);
+}
+
+static u32 thermal_mmio_readl(void __iomem *mmio_base)
+{
+	return readl(mmio_base);
+}
+
+static int thermal_mmio_get_temperature(void *private, int *temp)
+{
+	int t;
+	struct thermal_mmio *sensor =
+		(struct thermal_mmio *)private;
+
+	t = sensor->read_mmio(sensor->mmio_base) & sensor->mask;
+	t *= sensor->factor;
+	t += sensor->bias;
+	t /= sensor->divider;
+
+	*temp = t;
+
+	return 0;
+}
+
+static struct thermal_zone_of_device_ops thermal_mmio_ops = {
+	.get_temp = thermal_mmio_get_temperature,
+};
+
+static int thermal_mmio_parse_dt(struct platform_device *pdev,
+				 struct thermal_mmio *sensor)
+{
+	struct resource *resource;
+	int ret;
+
+	resource = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (IS_ERR(resource)) {
+		dev_err(&pdev->dev,
+			"fail to get platform memory resource (%ld)\n",
+			PTR_ERR(resource));
+		return PTR_ERR(resource);
+	}
+
+	sensor->mmio_base = devm_ioremap_resource(&pdev->dev, resource);
+	if (IS_ERR(sensor->mmio_base)) {
+		dev_err(&pdev->dev, "failed to ioremap memory (%ld)\n",
+			PTR_ERR(sensor->mmio_base));
+		return PTR_ERR(sensor->mmio_base);
+	}
+
+	ret = of_property_read_u32(pdev->dev.of_node, "sensor-width",
+				   &sensor->width);
+	if (ret < 0) {
+		sensor->width = THERMAL_MMIO_DEFAULT_SENSOR_WIDTH;
+		dev_dbg(&pdev->dev,
+			"sensor-width undefined (%d) - using default: %d\n",
+			ret, sensor->width);
+	}
+
+	ret = of_property_read_u32(pdev->dev.of_node, "sensor-mask",
+				   &sensor->mask);
+	if (ret < 0) {
+		sensor->mask = GENMASK(sizeof(u32) * BITS_PER_BYTE - 1, 0);
+		dev_dbg(&pdev->dev,
+			"sensor-mask undefined (%d) - using default: 0x%x\n",
+			ret, sensor->mask);
+	}
+
+	ret = of_property_read_s32(pdev->dev.of_node, "sensor-factor",
+				   &sensor->factor);
+	if (ret < 0) {
+		sensor->factor = THERMAL_MMIO_DEFAULT_SENSOR_FACTOR;
+		dev_dbg(&pdev->dev,
+			"sensor-factor undefined (%d) - using default: %d\n",
+			ret, sensor->factor);
+	}
+
+	ret = of_property_read_s32(pdev->dev.of_node, "sensor-bias",
+				   &sensor->bias);
+	if (ret < 0) {
+		sensor->bias = THERMAL_MMIO_DEFAULT_SENSOR_BIAS;
+		dev_dbg(&pdev->dev,
+			"sensor-bias undefined (%d) - using default: %d\n",
+			ret, sensor->bias);
+	}
+
+	ret = of_property_read_u32(pdev->dev.of_node, "sensor-divider",
+				   &sensor->divider);
+	if (ret < 0) {
+		sensor->divider = THERMAL_MMIO_DEFAULT_SENSOR_DIVIDER;
+		dev_dbg(&pdev->dev,
+			"sensor-divider undefined (%d) - using default: %d\n",
+			ret, sensor->divider);
+	}
+
+	/* configuration value sanity */
+	if (sensor->width > resource_size(resource)) {
+		dev_err(&pdev->dev,
+			"too small MMIO size, expected (%d) < supplied (%d)\n",
+			sensor->width, (int)resource_size(resource));
+		return -EINVAL;
+	}
+
+	dev_dbg(&pdev->dev,
+		"width=%d, mask=0x%x factor=%d bias=%d divider=%d\n",
+		sensor->width, sensor->mask, sensor->factor, sensor->bias,
+		sensor->divider);
+
+	return 0;
+}
+
+static int thermal_mmio_probe(struct platform_device *pdev)
+{
+	struct thermal_mmio *sensor;
+	struct thermal_zone_device *thermal_zone;
+	int ret;
+	int temperature;
+
+	sensor = devm_kzalloc(&pdev->dev, sizeof(*sensor), GFP_KERNEL);
+	if (!sensor)
+		return -ENOMEM;
+
+	ret = thermal_mmio_parse_dt(pdev, sensor);
+	if (ret) {
+		dev_err(&pdev->dev, "fail to parse dt\n");
+		return ret;
+	}
+
+	switch (sensor->width) {
+	case sizeof(u8):
+		sensor->read_mmio = thermal_mmio_readb;
+		break;
+	case sizeof(u16):
+		sensor->read_mmio = thermal_mmio_readw;
+		break;
+	case sizeof(u32):
+		sensor->read_mmio = thermal_mmio_readl;
+		break;
+	default:
+		dev_err(&pdev->dev, "bad sensor-width property supplied: %d\n",
+			sensor->width);
+		return -EINVAL;
+	}
+
+	thermal_zone = devm_thermal_zone_of_sensor_register(&pdev->dev,
+							    0,
+							    sensor,
+							    &thermal_mmio_ops);
+	if (IS_ERR(thermal_zone)) {
+		dev_err(&pdev->dev,
+			"failed to register sensor (%ld)\n",
+			PTR_ERR(thermal_zone));
+		return PTR_ERR(thermal_zone);
+	}
+
+	thermal_mmio_get_temperature(sensor, &temperature);
+	dev_info(&pdev->dev,
+		 "thermal mmio sensor %s registered, current temperature: %d\n",
+		 pdev->name, temperature);
+
+	return 0;
+}
+
+static const struct of_device_id thermal_mmio_id_table[] = {
+	{ .compatible = "thermal-mmio" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, thermal_mmio_id_table);
+
+static struct platform_driver thermal_mmio_driver = {
+	.probe = thermal_mmio_probe,
+	.driver = {
+		.name = "thermal-mmio",
+		.owner = THIS_MODULE,
+		.of_match_table = of_match_ptr(thermal_mmio_id_table),
+	},
+};
+
+module_platform_driver(thermal_mmio_driver);
+
+MODULE_AUTHOR("Talel Shenhar <talel@amazon.com>");
+MODULE_DESCRIPTION("Thermal MMIO Driver");
+MODULE_LICENSE("GPL v2");
-- 
2.7.4