drivers/input/touchscreen/cyttsp_spi.c

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

File Facts

System
Linux kernel
Corpus path
drivers/input/touchscreen/cyttsp_spi.c
Extension
.c
Size
4716 bytes
Lines
187
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

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Source for:
 * Cypress TrueTouch(TM) Standard Product (TTSP) SPI touchscreen driver.
 * For use with Cypress Txx3xx parts.
 * Supported parts include:
 * CY8CTST341
 * CY8CTMA340
 *
 * Copyright (C) 2009, 2010, 2011 Cypress Semiconductor, Inc.
 * Copyright (C) 2012 Javier Martinez Canillas <javier@dowhile0.org>
 * Copyright (C) 2013 Cypress Semiconductor
 *
 * Contact Cypress Semiconductor at www.cypress.com <ttdrivers@cypress.com>
 */

#include "cyttsp_core.h"

#include <linux/delay.h>
#include <linux/input.h>
#include <linux/spi/spi.h>

#define CY_SPI_NAME		"cyttsp-spi"

#define CY_SPI_WR_OP		0x00 /* r/~w */
#define CY_SPI_RD_OP		0x01
#define CY_SPI_CMD_BYTES	4
#define CY_SPI_SYNC_BYTE	2
#define CY_SPI_SYNC_ACK1	0x62 /* from protocol v.2 */
#define CY_SPI_SYNC_ACK2	0x9D /* from protocol v.2 */
#define CY_SPI_DATA_SIZE	128
#define CY_SPI_DATA_BUF_SIZE	(CY_SPI_CMD_BYTES + CY_SPI_DATA_SIZE)
#define CY_SPI_BITS_PER_WORD	8

static int cyttsp_spi_xfer(struct device *dev, u8 *xfer_buf,
			   u8 op, u16 reg, u8 *buf, int length)
{
	struct spi_device *spi = to_spi_device(dev);
	struct spi_message msg;
	struct spi_transfer xfer[2];
	u8 *wr_buf = &xfer_buf[0];
	u8 *rd_buf = &xfer_buf[CY_SPI_DATA_BUF_SIZE];
	int retval;
	int i;

	if (length > CY_SPI_DATA_SIZE) {
		dev_err(dev, "%s: length %d is too big.\n",
			__func__, length);
		return -EINVAL;
	}

	memset(wr_buf, 0, CY_SPI_DATA_BUF_SIZE);
	memset(rd_buf, 0, CY_SPI_DATA_BUF_SIZE);

	wr_buf[0] = 0x00; /* header byte 0 */
	wr_buf[1] = 0xFF; /* header byte 1 */
	wr_buf[2] = reg;  /* reg index */
	wr_buf[3] = op;   /* r/~w */
	if (op == CY_SPI_WR_OP)
		memcpy(wr_buf + CY_SPI_CMD_BYTES, buf, length);

	memset(xfer, 0, sizeof(xfer));
	spi_message_init(&msg);

	/*
	  We set both TX and RX buffers because Cypress TTSP
	  requires full duplex operation.
	*/
	xfer[0].tx_buf = wr_buf;
	xfer[0].rx_buf = rd_buf;
	switch (op) {
	case CY_SPI_WR_OP:
		xfer[0].len = length + CY_SPI_CMD_BYTES;
		spi_message_add_tail(&xfer[0], &msg);
		break;

	case CY_SPI_RD_OP:
		xfer[0].len = CY_SPI_CMD_BYTES;
		spi_message_add_tail(&xfer[0], &msg);

		xfer[1].rx_buf = buf;
		xfer[1].len = length;
		spi_message_add_tail(&xfer[1], &msg);
		break;

	default:
		dev_err(dev, "%s: bad operation code=%d\n", __func__, op);
		return -EINVAL;
	}

Annotation

Implementation Notes