/* i2c-stub.c - I2C/SMBus chip emulator Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com> Copyright (C) 2007 Jean Delvare <khali@linux-fr.org> This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that 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. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ #define DEBUG 1 #include <linux/init.h> #include <linux/module.h> #include <linux/kernel.h> #include <linux/slab.h> #include <linux/errno.h> #include <linux/i2c.h> #define MAX_CHIPS 10 static unsigned short chip_addr[MAX_CHIPS]; module_param_array(chip_addr, ushort, NULL, S_IRUGO); MODULE_PARM_DESC(chip_addr, "Chip addresses (up to 10, between 0x03 and 0x77)\n"); struct stub_chip { u8 pointer; u16 words[256]; /* Byte operations use the LSB as per SMBus specification */ }; static struct stub_chip *stub_chips; /* Return -1 on error. */ static s32 stub_xfer(struct i2c_adapter * adap, u16 addr, unsigned short flags, char read_write, u8 command, int size, union i2c_smbus_data * data) { s32 ret; int i; struct stub_chip *chip = NULL; /* Search for the right chip */ for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) { if (addr == chip_addr[i]) { chip = stub_chips + i; break; } } if (!chip) return -ENODEV; switch (size) { case I2C_SMBUS_QUICK: dev_dbg(&adap->dev, "smbus quick - addr 0x%02x\n", addr); ret = 0; break; case I2C_SMBUS_BYTE: if (read_write == I2C_SMBUS_WRITE) { chip->pointer = command; dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, " "wrote 0x%02x.\n", addr, command); } else { data->byte = chip->words[chip->pointer++] & 0xff; dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, " "read 0x%02x.\n", addr, data->byte); } ret = 0; break; case I2C_SMBUS_BYTE_DATA: if (read_write == I2C_SMBUS_WRITE) { chip->words[command] &= 0xff00; chip->words[command] |= data->byte; dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, " "wrote 0x%02x at 0x%02x.\n", addr, data->byte, command); } else { data->byte = chip->words[command] & 0xff; dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, " "read 0x%02x at 0x%02x.\n", addr, data->byte, command); } chip->pointer = command + 1; ret = 0; break; case I2C_SMBUS_WORD_DATA: if (read_write == I2C_SMBUS_WRITE) { chip->words[command] = data->word; dev_dbg(&adap->dev, "smbus word data - addr 0x%02x, " "wrote 0x%04x at 0x%02x.\n", addr, data->word, command); } else { data->word = chip->words[command]; dev_dbg(&adap->dev, "smbus word data - addr 0x%02x, " "read 0x%04x at 0x%02x.\n", addr, data->word, command); } ret = 0; break; default: dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n"); ret = -1; break; } /* switch (size) */ return ret; } static u32 stub_func(struct i2c_adapter *adapter) { return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA; } static const struct i2c_algorithm smbus_algorithm = { .functionality = stub_func, .smbus_xfer = stub_xfer, }; static struct i2c_adapter stub_adapter = { .owner = THIS_MODULE, .class = I2C_CLASS_HWMON, .algo = &smbus_algorithm, .name = "SMBus stub driver", }; static int __init i2c_stub_init(void) { int i, ret; if (!chip_addr[0]) { printk(KERN_ERR "i2c-stub: Please specify a chip address\n"); return -ENODEV; } for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) { if (chip_addr[i] < 0x03 || chip_addr[i] > 0x77) { printk(KERN_ERR "i2c-stub: Invalid chip address " "0x%02x\n", chip_addr[i]); return -EINVAL; } printk(KERN_INFO "i2c-stub: Virtual chip at 0x%02x\n", chip_addr[i]); } /* Allocate memory for all chips at once */ stub_chips = kzalloc(i * sizeof(struct stub_chip), GFP_KERNEL); if (!stub_chips) { printk(KERN_ERR "i2c-stub: Out of memory\n"); return -ENOMEM; } ret = i2c_add_adapter(&stub_adapter); if (ret) kfree(stub_chips); return ret; } static void __exit i2c_stub_exit(void) { i2c_del_adapter(&stub_adapter); kfree(stub_chips); } MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>"); MODULE_DESCRIPTION("I2C stub driver"); MODULE_LICENSE("GPL"); module_init(i2c_stub_init); module_exit(i2c_stub_exit);