diff options
Diffstat (limited to 'drivers/i2c/i2c-stub.c')
| -rw-r--r-- | drivers/i2c/i2c-stub.c | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/drivers/i2c/i2c-stub.c b/drivers/i2c/i2c-stub.c new file mode 100644 index 00000000000..d0a9c590c3c --- /dev/null +++ b/drivers/i2c/i2c-stub.c @@ -0,0 +1,220 @@ +/* + i2c-stub.c - I2C/SMBus chip emulator + + Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com> + Copyright (C) 2007, 2012 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 +#define STUB_FUNC (I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE | \ + I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA | \ + I2C_FUNC_SMBUS_I2C_BLOCK) + +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; +module_param(functionality, ulong, S_IRUGO | S_IWUSR); +MODULE_PARM_DESC(functionality, "Override functionality bitfield"); + +struct stub_chip { + u8 pointer; + u16 words[256]; /* Byte operations use the LSB as per SMBus + specification */ +}; + +static struct stub_chip *stub_chips; + +/* 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; + + /* 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; + + 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; + + 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 & 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 = kzalloc(i * sizeof(struct stub_chip), GFP_KERNEL); + if (!stub_chips) { + pr_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); |