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/*
i2c-stub.c - I2C/SMBus chip emulator
Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com>
Copyright (C) 2007-2014 Jean Delvare <jdelvare@suse.de>
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.
*/
#define DEBUG 1
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/slab.h>
#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");
/* Some chips have banked register ranges */
static u8 bank_reg[MAX_CHIPS];
module_param_array(bank_reg, byte, NULL, S_IRUGO);
MODULE_PARM_DESC(bank_reg, "Bank register");
static u8 bank_mask[MAX_CHIPS];
module_param_array(bank_mask, byte, NULL, S_IRUGO);
MODULE_PARM_DESC(bank_mask, "Bank value mask");
static u8 bank_start[MAX_CHIPS];
module_param_array(bank_start, byte, NULL, S_IRUGO);
MODULE_PARM_DESC(bank_start, "First banked register");
static u8 bank_end[MAX_CHIPS];
module_param_array(bank_end, byte, NULL, S_IRUGO);
MODULE_PARM_DESC(bank_end, "Last banked register");
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;
/* For chips with banks, extra registers are allocated dynamically */
u8 bank_reg;
u8 bank_shift;
u8 bank_mask;
u8 bank_sel; /* Currently selected bank */
u8 bank_start;
u8 bank_end;
u16 bank_size;
u16 *bank_words; /* Room for bank_mask * bank_size registers */
};
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;
}
static u16 *stub_get_wordp(struct stub_chip *chip, u8 offset)
{
if (chip->bank_sel &&
offset >= chip->bank_start && offset <= chip->bank_end)
return chip->bank_words +
(chip->bank_sel - 1) * chip->bank_size +
offset - chip->bank_start;
else
return chip->words + offset;
}
/* 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;
u16 *wordp;
/* 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 {
wordp = stub_get_wordp(chip, chip->pointer++);
data->byte = *wordp & 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:
wordp = stub_get_wordp(chip, command);
if (read_write == I2C_SMBUS_WRITE) {
*wordp &= 0xff00;
*wordp |= data->byte;
dev_dbg(&adap->dev,
"smbus byte data - addr 0x%02x, wrote 0x%02x at 0x%02x.\n",
addr, data->byte, command);
/* Set the bank as needed */
if (chip->bank_words && command == chip->bank_reg) {
chip->bank_sel =
(data->byte >> chip->bank_shift)
& chip->bank_mask;
dev_dbg(&adap->dev,
"switching to bank %u.\n",
chip->bank_sel);
}
} else {
data->byte = *wordp & 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:
wordp = stub_get_wordp(chip, command);
if (read_write == I2C_SMBUS_WRITE) {
*wordp = 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 = *wordp;
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:
/*
* We ignore banks here, because banked chips don't use I2C
* block transfers
*/
if (data->block[0] > 256 - command) /* Avoid overrun */
data->block[0] = 256 - command;
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:
/*
* We ignore banks here, because chips typically don't use both
* banks and SMBus block transfers
*/
b = stub_find_block(&adap->dev, chip, command, false);
if (read_write == I2C_SMBUS_WRITE) {
len = data
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