drivers/input/misc/ariel-pwrbutton.c

Source file repositories/reference/linux-study-clean/drivers/input/misc/ariel-pwrbutton.c

File Facts

System
Linux kernel
Corpus path
drivers/input/misc/ariel-pwrbutton.c
Extension
.c
Size
4119 bytes
Lines
171
Domain
Driver Families
Bucket
drivers/input
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 ec_input_response {
	u8 reserved;
	u8 header;
	u8 data[3];
} __packed;

struct ariel_pwrbutton {
	struct spi_device *client;
	struct input_dev *input;
	u8 msg_counter;
};

static int ec_input_read(struct ariel_pwrbutton *priv,
			 struct ec_input_response *response)
{
	u8 read_request[] = { 0x00, 0x5a, 0xa5, 0x00, 0x00 };
	struct spi_device *spi = priv->client;
	struct spi_transfer t = {
		.tx_buf = read_request,
		.rx_buf = response,
		.len = sizeof(read_request),
	};

	compiletime_assert(sizeof(read_request) == sizeof(*response),
			   "SPI xfer request/response size mismatch");

	return spi_sync_transfer(spi, &t, 1);
}

static irqreturn_t ec_input_interrupt(int irq, void *dev_id)
{
	struct ariel_pwrbutton *priv = dev_id;
	struct spi_device *spi = priv->client;
	struct ec_input_response response;
	int error;
	int i;

	error = ec_input_read(priv, &response);
	if (error < 0) {
		dev_err(&spi->dev, "EC read failed: %d\n", error);
		goto out;
	}

	if (priv->msg_counter == RESP_COUNTER(response)) {
		dev_warn(&spi->dev, "No new data to read?\n");
		goto out;
	}

	priv->msg_counter = RESP_COUNTER(response);

	if (RESP_TYPE(response) != 0x3 && RESP_TYPE(response) != 0xc) {
		dev_dbg(&spi->dev, "Ignoring message that's not kbd data\n");
		goto out;
	}

	for (i = 0; i < RESP_SIZE(response); i++) {
		switch (response.data[i]) {
		case 0x74:
			input_report_key(priv->input, KEY_POWER, 1);
			input_sync(priv->input);
			break;
		case 0xf4:
			input_report_key(priv->input, KEY_POWER, 0);
			input_sync(priv->input);
			break;
		default:
			dev_dbg(&spi->dev, "Unknown scan code: %02x\n",
				response.data[i]);
		}
	}

out:
	return IRQ_HANDLED;
}

static int ariel_pwrbutton_probe(struct spi_device *spi)
{
	struct ec_input_response response;
	struct ariel_pwrbutton *priv;
	int error;

	if (!spi->irq) {
		dev_err(&spi->dev, "Missing IRQ.\n");
		return -EINVAL;
	}

	priv = devm_kzalloc(&spi->dev, sizeof(*priv), GFP_KERNEL);
	if (!priv)
		return -ENOMEM;

Annotation

Implementation Notes