/* i2c-stub.c - I2C/SMBus chip emulator Copyright (c) 2004 Mark M. Hoffman Copyright (C) 2007, 2012 Jean Delvare 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 #include #include #include #include #include #include #define MAX_CHIPS 10 /* * Support for I2C_FUNC_SMBUS_BLOCK_DATA is disabled by default and must * be enabled explicitly by setting the I2C_FUNC_SMBUS_BLOCK_DATA bits * in the 'functionality' module parameter. */ #define STUB_FUNC_DEFAULT \ (I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE | \ I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA | \ I2C_FUNC_SMBUS_I2C_BLOCK) #define STUB_FUNC_ALL \ (STUB_FUNC_DEFAULT | I2C_FUNC_SMBUS_BLOCK_DATA) 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)"); static unsigned long functionality = STUB_FUNC_DEFAULT; module_param(functionality, ulong, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(functionality, "Override functionality bitfield"); struct smbus_block_data { struct list_head node; u8 command; u8 len; u8 block[I2C_SMBUS_BLOCK_MAX]; }; struct stub_chip { u8 pointer; u16 words[256]; /* Byte operations use the LSB as per SMBus specification */ struct list_head smbus_blocks; }; static struct stub_chip *stub_chips; static int stub_chips_nr; static struct smbus_block_data *stub_find_block(struct device *dev, struct stub_chip *chip, u8 command, bool create) { struct smbus_block_data *b, *rb = NULL; list_for_each_entry(b, &chip->smbus_blocks, node) { if (b->command == command) { rb = b; break; } } if (rb == NULL && create) { rb = devm_kzalloc(dev, sizeof(*rb), GFP_KERNEL); if (rb == NULL) return rb; rb->command = command; list_add(&rb->node, &chip->smbus_blocks); } return rb; } /* Return negative errno 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, len; struct stub_chip *chip = NULL; struct smbus_block_data *b; /* Search for the right chip */ for (i = 0; i < stub_chips_nr; 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; case I2C_SMBUS_I2C_BLOCK_DATA: len = data->block[0]; if (read_write == I2C_SMBUS_WRITE) { for (i = 0; i < len; i++) { chip->words[command + i] &= 0xff00; chip->words[command + i] |= data->block[1 + i]; } dev_dbg(&adap->dev, "i2c block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n", addr, len, command); } else { for (i = 0; i < len; i++) { data->block[1 + i] = chip->words[command + i] & 0xff; } dev_dbg(&adap->dev, "i2c block data - addr 0x%02x, read %d bytes at 0x%02x.\n", addr, len, command); } ret = 0; break; case I2C_SMBUS_BLOCK_DATA: b = stub_find_block(&adap->dev, chip, command, false); if (read_write == I2C_SMBUS_WRITE) { len = data->block[0]; if (len == 0 || len > I2C_SMBUS_BLOCK_MAX) { ret = -EINVAL; break; } if (b == NULL) { b = stub_find_block(&adap->dev, chip, command, true); if (b == NULL) { ret = -ENOMEM; break; } } /* Largest write sets read block length */ if (len > b->len) b->len = len; for (i = 0; i < len; i++) b->block[i] = data->block[i + 1]; /* update for byte and word commands */ chip->words[command] = (b->block[0] << 8) | b->len; dev_dbg(&adap->dev, "smbus block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n", addr, len, command); } else { if (b == NULL) { dev_dbg(&adap->dev, "SMBus block read command without prior block write not supported\n"); ret = -EOPNOTSUPP; break; } len = b->len; data->block[0] = len; for (i = 0; i < len; i++) data->block[i + 1] = b->block[i]; dev_dbg(&adap->dev, "smbus block data - addr 0x%02x, read %d bytes at 0x%02x.\n", addr, len, command); } ret = 0; break; default: dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n"); ret = -EOPNOTSUPP; break; } /* switch (size) */ return ret; } static u32 stub_func(struct i2c_adapter *adapter) { return STUB_FUNC_ALL & functionality; } 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 | I2C_CLASS_SPD, .algo = &smbus_algorithm, .name = "SMBus stub driver", }; static int __init i2c_stub_init(void) { int i, ret; if (!chip_addr[0]) { pr_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) { pr_err("i2c-stub: Invalid chip address 0x%02x\n", chip_addr[i]); return -EINVAL; } pr_info("i2c-stub: Virtual chip at 0x%02x\n", chip_addr[i]); } /* Allocate memory for all chips at once */ stub_chips_nr = i; stub_chips = kcalloc(stub_chips_nr, sizeof(struct stub_chip), GFP_KERNEL); if (!stub_chips) { pr_err("i2c-stub: Out of memory\n"); return -ENOMEM; } for (i = 0; i < stub_chips_nr; i++) INIT_LIST_HEAD(&stub_chips[i].smbus_blocks); 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 "); MODULE_DESCRIPTION("I2C stub driver"); MODULE_LICENSE("GPL"); module_init(i2c_stub_init); module_exit(i2c_stub_exit);