drivers/input/touchscreen/jornada720_ts.c

Source file repositories/reference/linux-study-clean/drivers/input/touchscreen/jornada720_ts.c

File Facts

System
Linux kernel
Corpus path
drivers/input/touchscreen/jornada720_ts.c
Extension
.c
Size
4242 bytes
Lines
158
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 jornada_ts {
	struct input_dev *dev;
	struct gpio_desc *gpio;
	int x_data[4];		/* X sample values */
	int y_data[4];		/* Y sample values */
};

static void jornada720_ts_collect_data(struct jornada_ts *jornada_ts)
{
	/* 3 low word X samples */
	jornada_ts->x_data[0] = jornada_ssp_byte(TXDUMMY);
	jornada_ts->x_data[1] = jornada_ssp_byte(TXDUMMY);
	jornada_ts->x_data[2] = jornada_ssp_byte(TXDUMMY);

	/* 3 low word Y samples */
	jornada_ts->y_data[0] = jornada_ssp_byte(TXDUMMY);
	jornada_ts->y_data[1] = jornada_ssp_byte(TXDUMMY);
	jornada_ts->y_data[2] = jornada_ssp_byte(TXDUMMY);

	/* combined x samples bits */
	jornada_ts->x_data[3] = jornada_ssp_byte(TXDUMMY);

	/* combined y samples bits */
	jornada_ts->y_data[3] = jornada_ssp_byte(TXDUMMY);
}

static int jornada720_ts_average(int coords[4])
{
	int coord, high_bits = coords[3];

	coord  = coords[0] | ((high_bits & 0x03) << 8);
	coord += coords[1] | ((high_bits & 0x0c) << 6);
	coord += coords[2] | ((high_bits & 0x30) << 4);

	return coord / 3;
}

static irqreturn_t jornada720_ts_interrupt(int irq, void *dev_id)
{
	struct platform_device *pdev = dev_id;
	struct jornada_ts *jornada_ts = platform_get_drvdata(pdev);
	struct input_dev *input = jornada_ts->dev;
	int x, y;

	/* If gpio is high then report pen up */
	if (gpiod_get_value(jornada_ts->gpio)) {
		input_report_key(input, BTN_TOUCH, 0);
		input_sync(input);
	} else {
		jornada_ssp_start();

		/* proper reply to request is always TXDUMMY */
		if (jornada_ssp_inout(GETTOUCHSAMPLES) == TXDUMMY) {
			jornada720_ts_collect_data(jornada_ts);

			x = jornada720_ts_average(jornada_ts->x_data);
			y = jornada720_ts_average(jornada_ts->y_data);

			input_report_key(input, BTN_TOUCH, 1);
			input_report_abs(input, ABS_X, x);
			input_report_abs(input, ABS_Y, y);
			input_sync(input);
		}

		jornada_ssp_end();
	}

	return IRQ_HANDLED;
}

static int jornada720_ts_probe(struct platform_device *pdev)
{
	struct jornada_ts *jornada_ts;
	struct input_dev *input_dev;
	int error, irq;

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

	input_dev = devm_input_allocate_device(&pdev->dev);
	if (!input_dev)
		return -ENOMEM;

	platform_set_drvdata(pdev, jornada_ts);

	jornada_ts->gpio = devm_gpiod_get(&pdev->dev, "penup", GPIOD_IN);
	if (IS_ERR(jornada_ts->gpio))
		return PTR_ERR(jornada_ts->gpio);

Annotation

Implementation Notes