path: root/drivers/hid/hid-cp2112.c

/*
 * hid-cp2112.c - Silicon Labs HID USB to SMBus master bridge
 * Copyright (c) 2013,2014 Uplogix, Inc.
 * David Barksdale <dbarksdale@uplogix.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 */

/*
 * The Silicon Labs CP2112 chip is a USB HID device which provides an
 * SMBus controller for talking to slave devices and 8 GPIO pins. The
 * host communicates with the CP2112 via raw HID reports.
 *
 * Data Sheet:
 *   http://www.silabs.com/Support%20Documents/TechnicalDocs/CP2112.pdf
 * Programming Interface Specification:
 *   http://www.silabs.com/Support%20Documents/TechnicalDocs/AN495.pdf
 */

#include <linux/gpio.h>
#include <linux/hid.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/nls.h>
#include <linux/usb/ch9.h>
#include "hid-ids.h"

enum {
	CP2112_GPIO_CONFIG		= 0x02,
	CP2112_GPIO_GET			= 0x03,
	CP2112_GPIO_SET			= 0x04,
	CP2112_GET_VERSION_INFO		= 0x05,
	CP2112_SMBUS_CONFIG		= 0x06,
	CP2112_DATA_READ_REQUEST	= 0x10,
	CP2112_DATA_WRITE_READ_REQUEST	= 0x11,
	CP2112_DATA_READ_FORCE_SEND	= 0x12,
	CP2112_DATA_READ_RESPONSE	= 0x13,
	CP2112_DATA_WRITE_REQUEST	= 0x14,
	CP2112_TRANSFER_STATUS_REQUEST	= 0x15,
	CP2112_TRANSFER_STATUS_RESPONSE	= 0x16,
	CP2112_CANCEL_TRANSFER		= 0x17,
	CP2112_LOCK_BYTE		= 0x20,
	CP2112_USB_CONFIG		= 0x21,
	CP2112_MANUFACTURER_STRING	= 0x22,
	CP2112_PRODUCT_STRING		= 0x23,
	CP2112_SERIAL_STRING		= 0x24,
};

enum {
	STATUS0_IDLE		= 0x00,
	STATUS0_BUSY		= 0x01,
	STATUS0_COMPLETE	= 0x02,
	STATUS0_ERROR		= 0x03,
};

enum {
	STATUS1_TIMEOUT_NACK		= 0x00,
	STATUS1_TIMEOUT_BUS		= 0x01,
	STATUS1_ARBITRATION_LOST	= 0x02,
	STATUS1_READ_INCOMPLETE		= 0x03,
	STATUS1_WRITE_INCOMPLETE	= 0x04,
	STATUS1_SUCCESS			= 0x05,
};

struct cp2112_smbus_config_report {
	u8 report;		/* CP2112_SMBUS_CONFIG */
	__be32 clock_speed;	/* Hz */
	u8 device_address;	/* Stored in the upper 7 bits */
	u8 auto_send_read;	/* 1 = enabled, 0 = disabled */
	__be16 write_timeout;	/* ms, 0 = no timeout */
	__be16 read_timeout;	/* ms, 0 = no timeout */
	u8 scl_low_timeout;	/* 1 = enabled, 0 = disabled */
	__be16 retry_time;	/* # of retries, 0 = no limit */
} __packed;

struct cp2112_usb_config_report {
	u8 report;	/* CP2112_USB_CONFIG */
	__le16 vid;	/* Vendor ID */
	__le16 pid;	/* Product ID */
	u8 max_power;	/* Power requested in 2mA units */
	u8 power_mode;	/* 0x00 = bus powered
			   0x01 = self powered & regulator off
			   0x02 = self powered & regulator on */
	u8 release_major;
	u8 release_minor;
	u8 mask;	/* What fields to program */
} __packed;

struct cp2112_read_req_report {
	u8 report;	/* CP2112_DATA_READ_REQUEST */
	u8 slave_address;
	__be16 length;
} __packed;

struct cp2112_write_read_req_report {
	u8 report;	/* CP2112_DATA_WRITE_READ_REQUEST */
	u8 slave_address;
	__be16 length;
	u8 target_address_length;
	u8 target_address[16];
} __packed;

struct cp2112_write_req_report {
	u8 report;	/* CP2112_DATA_WRITE_REQUEST */
	u8 slave_address;
	u8 length;
	u8 data[61];
} __packed;

struct cp2112_force_read_report {
	u8 report;	/* CP2112_DATA_READ_FORCE_SEND */
	__be16 length;
} __packed;

struct cp2112_xfer_status_report {
	u8 report;	/* CP2112_TRANSFER_STATUS_RESPONSE */
	u8 status0;	/* STATUS0_* */
	u8 status1;	/* STATUS1_* */
	__be16 retries;
	__be16 length;
} __packed;

struct cp2112_string_report {
	u8 dummy;		/* force .string to be aligned */
	u8 report;		/* CP2112_*_STRING */
	u8 length;		/* length in bytes of everyting after .report */
	u8 type;		/* USB_DT_STRING */
	wchar_t string[30];	/* UTF16_LITTLE_ENDIAN string */
} __packed;

/* Number of times to request transfer status before giving up waiting for a
   transfer to complete. This may need to be changed if SMBUS clock, retries,
   or read/write/scl_low timeout settings are changed. */
static const int XFER_STATUS_RETRIES = 10;

/* Time in ms to wait for a CP2112_DATA_READ_RESPONSE or
   CP2112_TRANSFER_STATUS_RESPONSE. */
static const int RESPONSE_TIMEOUT = 50;

static const struct hid_device_id cp2112_devices[] = {
	{ HID_USB_DEVICE(USB_VENDOR_ID_CYGNAL, USB_DEVICE_ID_CYGNAL_CP2112) },
	{ }
};
MODULE_DEVICE_TABLE(hid, cp2112_devices);

struct cp2112_device {
	struct i2c_adapter adap;
	struct hid_device *hdev;
	wait_queue_head_t wait;
	u8 read_data[61];