path: root/drivers/hid/hid-ft260.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * hid-ft260.c - FTDI FT260 USB HID to I2C host bridge
 *
 * Copyright (c) 2021, Michael Zaidman <michaelz@xsightlabs.com>
 *
 * Data Sheet:
 *   https://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT260.pdf
 */

#include "hid-ids.h"
#include <linux/hidraw.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/usb.h>

#ifdef DEBUG
static int ft260_debug = 1;
#else
static int ft260_debug;
#endif
module_param_named(debug, ft260_debug, int, 0600);
MODULE_PARM_DESC(debug, "Toggle FT260 debugging messages");

#define ft260_dbg(format, arg...)					  \
	do {								  \
		if (ft260_debug)					  \
			pr_info("%s: " format, __func__, ##arg);	  \
	} while (0)

#define FT260_REPORT_MAX_LENGTH (64)
#define FT260_I2C_DATA_REPORT_ID(len) (FT260_I2C_REPORT_MIN + (len - 1) / 4)

#define FT260_WAKEUP_NEEDED_AFTER_MS (4800) /* 5s minus 200ms margin */

/*
 * The ft260 input report format defines 62 bytes for the data payload, but
 * when requested 62 bytes, the controller returns 60 and 2 in separate input
 * reports. To achieve better performance with the multi-report read data
 * transfers, we set the maximum read payload length to a multiple of 60.
 * With a 100 kHz I2C clock, one 240 bytes read takes about 1/27 second,
 * which is excessive; On the other hand, some higher layer drivers like at24
 * or optoe limit the i2c reads to 128 bytes. To not block other drivers out
 * of I2C for potentially troublesome amounts of time, we select the maximum
 * read payload length to be 180 bytes.
*/
#define FT260_RD_DATA_MAX (180)
#define FT260_WR_DATA_MAX (60)

/*
 * Device interface configuration.
 * The FT260 has 2 interfaces that are controlled by DCNF0 and DCNF1 pins.
 * First implementes USB HID to I2C bridge function and
 * second - USB HID to UART bridge function.
 */
enum {
	FT260_MODE_ALL			= 0x00,
	FT260_MODE_I2C			= 0x01,
	FT260_MODE_UART			= 0x02,
	FT260_MODE_BOTH			= 0x03,
};

/* Control pipe */
enum {
	FT260_GET_RQST_TYPE		= 0xA1,
	FT260_GET_REPORT		= 0x01,
	FT260_SET_RQST_TYPE		= 0x21,
	FT260_SET_REPORT		= 0x09,
	FT260_FEATURE			= 0x03,
};

/* Report IDs / Feature In */
enum {
	FT260_CHIP_VERSION		= 0xA0,
	FT260_SYSTEM_SETTINGS		= 0xA1,
	FT260_I2C_STATUS		= 0xC0,
	FT260_I2C_READ_REQ		= 0xC2,
	FT260_I2C_REPORT_MIN		= 0xD0,
	FT260_I2C_REPORT_MAX		= 0xDE,
	FT260_GPIO			= 0xB0,
	FT260_UART_INTERRUPT_STATUS	= 0xB1,
	FT260_UART_STATUS		= 0xE0,
	FT260_UART_RI_DCD_STATUS	= 0xE1,
	FT260_UART_REPORT		= 0xF0,
};

/* Feature Out */
enum {
	FT260_SET_CLOCK			= 0x01,
	FT260_SET_I2C_MODE		= 0x02,
	FT260_SET_UART_MODE		= 0x03,
	FT260_ENABLE_INTERRUPT		= 0x05,
	FT260_SELECT_GPIO2_FUNC		= 0x06,
	FT260_ENABLE_UART_DCD_RI	= 0x07,
	FT260_SELECT_GPIOA_FUNC		= 0x08,
	FT260_SELECT_GPIOG_FUNC		= 0x09,
	FT260_SET_INTERRUPT_TRIGGER	= 0x0A,
	FT260_SET_SUSPEND_OUT_POLAR	= 0x0B,
	FT260_ENABLE_UART_RI_WAKEUP	= 0x0C,
	FT260_SET_UART_RI_WAKEUP_CFG	= 0x0D,
	FT260_SET_I2C_RESET		= 0x20,
	FT260_SET_I2C_CLOCK_SPEED	= 0x22,
	FT260_SET_UART_RESET		= 0x40,
	FT260_SET_UART_CONFIG		= 0x41,
	FT260_SET_UART_BAUD_RATE	= 0x42,
	FT260_SET_UART_DATA_BIT		= 0x43,
	FT260_SET_UART_PARITY		= 0x44,
	FT260_SET_UART_STOP_BIT		= 0x45,
	FT260_SET_UART_BREAKING		= 0x46,
	FT260_SET_UART_XON_XOFF		= 0x49,
};

/* Response codes in I2C status report */
enum {
	FT260_I2C_STATUS_SUCCESS	= 0x00,
	FT260_I2C_STATUS_CTRL_BUSY	= 0x01,
	FT260_I2C_STATUS_ERROR		= 0x02,
	FT260_I2C_STATUS_ADDR_NO_ACK	= 0x04,
	FT260_I2C_STATUS_DATA_NO_ACK	= 0x08,
	FT260_I2C_STATUS_ARBITR_LOST	= 0x10,
	FT260_I2C_STATUS_CTRL_IDLE	= 0x20,
	FT260_I2C_STATUS_BUS_BUSY	= 0x40,
};

/* I2C Conditions flags */
enum {
	FT260_FLAG_NONE			= 0x00,
	FT260_FLAG_START		= 0x02,
	FT260_FLAG_START_REPEATED	= 0x03,
	FT260_FLAG_STOP			= 0x04,
	FT260_FLAG_START_STOP		= 0x06,
	FT260_FLAG_START_STOP_REPEATED	= 0x07,
};

#define FT260_SET_REQUEST_VALUE(report_id) ((FT260_FEATURE << 8) | report_id)

/* Feature In reports */

struct ft260_get_chip_version_report {
	u8 report;		/* FT260_CHIP_VERSION */
	u8 chip_code[4];	/* FTDI chip identification code */
	u8 reserved[8];
} __packed;

struct ft260_get_system_status_report {
	u8 report;		/* FT260_SYSTEM_SETTINGS */
	u8 chip_mode;		/* DCNF0 and DCNF1 status, bits 0-1 */
	u8 clock_ctl;		/* 0 - 12MHz, 1 - 24MHz, 2 - 48MHz */
	u8 suspend_status;	/* 0 - not suspended, 1 - suspended */
	u8 pwren_status;	/* 0 - FT260 is not ready, 1 - ready */
	u8 i2c_enable;		/* 0 - disabled, 1 - enabled */
	u8 uart_mode;		/* 0 - OFF; 1 - RTS_CTS, 2