drivers/hwmon/raspberrypi-hwmon.c

Source file repositories/reference/linux-study-clean/drivers/hwmon/raspberrypi-hwmon.c

File Facts

System
Linux kernel
Corpus path
drivers/hwmon/raspberrypi-hwmon.c
Extension
.c
Size
6927 bytes
Lines
293
Domain
Driver Families
Bucket
drivers/hwmon
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct rpi_hwmon_data {
	struct device *hwmon_dev;
	struct rpi_firmware *fw;
	u32 valid_inputs;
	u32 last_throttled;
	struct delayed_work get_values_poll_work;
};

static const char * const rpi_hwmon_labels[] = {
	"core",
	"sdram_c",
	"sdram_i",
	"sdram_p",
};

static void rpi_firmware_get_throttled(struct rpi_hwmon_data *data)
{
	u32 new_uv, old_uv, value;
	int ret;

	/* Request firmware to clear sticky bits */
	value = 0xffff;

	ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_THROTTLED,
				    &value, sizeof(value));
	if (ret) {
		dev_err_once(data->hwmon_dev, "Failed to get throttled (%d)\n",
			     ret);
		return;
	}

	new_uv = value & UNDERVOLTAGE_STICKY_BIT;
	old_uv = data->last_throttled & UNDERVOLTAGE_STICKY_BIT;
	data->last_throttled = value;

	if (new_uv == old_uv)
		return;

	if (new_uv)
		dev_crit(data->hwmon_dev, "Undervoltage detected!\n");
	else
		dev_info(data->hwmon_dev, "Voltage normalised\n");

	hwmon_notify_event(data->hwmon_dev, hwmon_in, hwmon_in_lcrit_alarm, 0);
}

static int rpi_firmware_get_voltage(struct rpi_hwmon_data *data, u32 id,
				    long *val)
{
	struct rpi_firmware_get_voltage_request packet =
		RPI_FIRMWARE_GET_VOLTAGE_REQUEST(id);
	int ret;

	ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_VOLTAGE,
				    &packet, sizeof(packet));
	if (ret)
		return ret;

	*val = le32_to_cpu(packet.value) / 1000;
	return 0;
}

static void get_values_poll(struct work_struct *work)
{
	struct rpi_hwmon_data *data;

	data = container_of(work, struct rpi_hwmon_data,
			    get_values_poll_work.work);

	rpi_firmware_get_throttled(data);

	/*
	 * We can't run faster than the sticky shift (100ms) since we get
	 * flipping in the sticky bits that are cleared.
	 */
	schedule_delayed_work(&data->get_values_poll_work, 2 * HZ);
}

static void rpi_hwmon_cancel_poll_work(void *res)
{
	struct rpi_hwmon_data *data = res;

	disable_delayed_work_sync(&data->get_values_poll_work);
}

static int rpi_read(struct device *dev, enum hwmon_sensor_types type,
		    u32 attr, int channel, long *val)
{
	struct rpi_hwmon_data *data = dev_get_drvdata(dev);

Annotation

Implementation Notes