drivers/input/keyboard/nspire-keypad.c

Source file repositories/reference/linux-study-clean/drivers/input/keyboard/nspire-keypad.c

File Facts

System
Linux kernel
Corpus path
drivers/input/keyboard/nspire-keypad.c
Extension
.c
Size
7008 bytes
Lines
278
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 nspire_keypad {
	void __iomem *reg_base;
	u32 int_mask;

	struct input_dev *input;
	struct clk *clk;

	struct matrix_keymap_data *keymap;
	int row_shift;

	/* Maximum delay estimated assuming 33MHz APB */
	u32 scan_interval;	/* In microseconds (~2000us max) */
	u32 row_delay;		/* In microseconds (~500us max) */

	u16 state[KEYPAD_BITMASK_ROWS];

	bool active_low;
};

static irqreturn_t nspire_keypad_irq(int irq, void *dev_id)
{
	struct nspire_keypad *keypad = dev_id;
	struct input_dev *input = keypad->input;
	unsigned short *keymap = input->keycode;
	unsigned int code;
	int row, col;
	u32 int_sts;
	u16 state[8];
	u16 bits, changed;

	int_sts = readl(keypad->reg_base + KEYPAD_INT) & keypad->int_mask;
	if (!int_sts)
		return IRQ_NONE;

	memcpy_fromio(state, keypad->reg_base + KEYPAD_DATA, sizeof(state));

	for (row = 0; row < KEYPAD_BITMASK_ROWS; row++) {
		bits = state[row];
		if (keypad->active_low)
			bits = ~bits;

		changed = bits ^ keypad->state[row];
		if (!changed)
			continue;

		keypad->state[row] = bits;

		for (col = 0; col < KEYPAD_BITMASK_COLS; col++) {
			if (!(changed & (1U << col)))
				continue;

			code = MATRIX_SCAN_CODE(row, col, keypad->row_shift);
			input_event(input, EV_MSC, MSC_SCAN, code);
			input_report_key(input, keymap[code],
					 bits & (1U << col));
		}
	}

	input_sync(input);

	writel(0x3, keypad->reg_base + KEYPAD_INT);

	return IRQ_HANDLED;
}

static int nspire_keypad_open(struct input_dev *input)
{
	struct nspire_keypad *keypad = input_get_drvdata(input);
	unsigned long val = 0, cycles_per_us, delay_cycles, row_delay_cycles;
	int error;

	error = clk_prepare_enable(keypad->clk);
	if (error)
		return error;

	cycles_per_us = (clk_get_rate(keypad->clk) / 1000000);
	if (cycles_per_us == 0)
		cycles_per_us = 1;

	delay_cycles = cycles_per_us * keypad->scan_interval;
	WARN_ON(delay_cycles >= (1 << 16)); /* Overflow */
	delay_cycles &= 0xffff;

	row_delay_cycles = cycles_per_us * keypad->row_delay;
	WARN_ON(row_delay_cycles >= (1 << 14)); /* Overflow */
	row_delay_cycles &= 0x3fff;

	val |= 3 << 0; /* Set scan mode to 3 (continuous scan) */
	val |= row_delay_cycles << 2; /* Delay between scanning each row */
	val |= delay_cycles << 16; /* Delay between scans */

Annotation

Implementation Notes