https://github.com/maximilianfeldthusen/i2c-sensor-driver
i2c-sensor-driver
https://github.com/maximilianfeldthusen/i2c-sensor-driver
c driver i2c linux linux-kernel sensor spdx
Last synced: about 1 month ago
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i2c-sensor-driver
- Host: GitHub
- URL: https://github.com/maximilianfeldthusen/i2c-sensor-driver
- Owner: maximilianfeldthusen
- License: mit
- Created: 2025-08-13T03:29:51.000Z (about 2 months ago)
- Default Branch: TFD
- Last Pushed: 2025-08-13T03:41:33.000Z (about 2 months ago)
- Last Synced: 2025-08-13T05:34:39.933Z (about 2 months ago)
- Topics: c, driver, i2c, linux, linux-kernel, sensor, spdx
- Language: C
- Homepage:
- Size: 15.6 KB
- Stars: 0
- Watchers: 0
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# i2c-sensor-driver
## License Declaration
```c
// SPDX-License-Identifier: MIT
```
- Declares the license using the SPDX identifier.
- Required for kernel contributions; this one uses **MIT**.
---
## Header Inclusions
```c
#include
#include
#include
#include
#include
```
- `module.h`: For kernel module infrastructure.
- `i2c.h`: For I²C device and driver APIs.
- `hwmon.h` and `hwmon-sysfs.h`: For integrating with the hwmon subsystem.
- `slab.h`: For memory allocation (`kzalloc`).
---
## Register Definition
```c
#define ACME_REG_TEMP 0x00
```
- Defines the register address where the sensor stores temperature data.
---
## Driver Data Structure
```c
struct acme_data {
struct i2c_client *client;
};
```
- Holds per-device data.
- `i2c_client` represents the I²C device instance.
---
## Temperature Read Function
```c
static int acme_read_temp(struct acme_data *data, long *val)
```
- Reads a 16-bit word from the temperature register.
- Converts it from **big-endian** to host-endian.
- Stores the result in `val` (assumed to be in milli-Celsius).
- Returns 0 on success or a negative error code.
---
## hwmon Read Callback
```c
static int acme_hwmon_read(...)
```
- Called by the hwmon subsystem when userspace reads `temp1_input`.
- Verifies the sensor type and attribute.
- Delegates to `acme_read_temp()`.
---
## hwmon Operations
```c
static const struct hwmon_ops acme_hwmon_ops = {
.read = acme_hwmon_read,
};
```
- Defines the read callback for hwmon.
---
## hwmon Channel Info
```c
static const struct hwmon_channel_info *acme_info[] = {
HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
NULL
};
```
- Declares that this driver exposes one temperature input.
---
## hwmon Chip Info
```c
static const struct hwmon_chip_info acme_chip_info = {
.ops = &acme_hwmon_ops,
.info = acme_info,
};
```
- Combines the ops and channel info into a single structure.
---
## Probe Function
```c
static int acme_probe(struct i2c_client *client, ...)
```
- Called when the kernel matches this driver to a device.
- Allocates memory for `acme_data`.
- Stores the `i2c_client` pointer.
- Registers the device with hwmon using `devm_hwmon_device_register_with_info()`.
- Returns 0 on success or an error code.
---
## Device Matching Tables
```c
static const struct i2c_device_id acme_id[] = { ... };
static const struct of_device_id acme_of_match[] = { ... };
```
- Allow matching via legacy board files (`i2c_device_id`) or Device Tree (`of_device_id`).
---
## Driver Registration
```c
static struct i2c_driver acme_driver = { ... };
module_i2c_driver(acme_driver);
```
- Defines the driver and registers it with the kernel.
- `module_i2c_driver()` sets up init/exit functions automatically.
---
## Module Metadata
```c
MODULE_AUTHOR("Your Name");
MODULE_DESCRIPTION("ACME Temperature Sensor Driver (hwmon)");
MODULE_LICENSE("MIT");
```
- Provides metadata for tools like `modinfo`.
---
## What This Driver Does
- Talks to a simple I²C temperature sensor.
- Reads temperature from a register.
- Exposes it via the standard hwmon interface (`/sys/class/hwmon/.../temp1_input`).
- Compatible with tools like `sensors`.