Commit 9d90c1fd authored by Jean Delvare's avatar Jean Delvare Committed by Jean Delvare

i2c-stub: Support multiple chips

Add support for multiple chips to i2c-stub. I've changed the memory
allocation scheme from static to dynamic, so that we don't waste too
much memory.
Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
Acked-by: default avatarMark M. Hoffman <mhoffman@lightlink.com>
parent 567a244b
......@@ -6,13 +6,14 @@ This module is a very simple fake I2C/SMBus driver. It implements four
types of SMBus commands: write quick, (r/w) byte, (r/w) byte data, and
(r/w) word data.
You need to provide a chip address as a module parameter when loading
this driver, which will then only react to SMBus commands to this address.
You need to provide chip addresses as a module parameter when loading this
driver, which will then only react to SMBus commands to these addresses.
No hardware is needed nor associated with this module. It will accept write
quick commands to one address; it will respond to the other commands (also
to one address) by reading from or writing to an array in memory. It will
also spam the kernel logs for every command it handles.
quick commands to the specified addresses; it will respond to the other
commands (also to the specified addresses) by reading from or writing to
arrays in memory. It will also spam the kernel logs for every command it
handles.
A pointer register with auto-increment is implemented for all byte
operations. This allows for continuous byte reads like those supported by
......@@ -26,8 +27,8 @@ The typical use-case is like this:
PARAMETERS:
int chip_addr:
The SMBus address to emulate a chip at.
int chip_addr[10]:
The SMBus addresses to emulate chips at.
CAVEATS:
......@@ -41,9 +42,6 @@ If the hardware for your driver has banked registers (e.g. Winbond sensors
chips) this module will not work well - although it could be extended to
support that pretty easily.
Only one chip address is supported - although this module could be
extended to support more.
If you spam it hard enough, printk can be lossy. This module really wants
something like relayfs.
......@@ -24,24 +24,41 @@
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/i2c.h>
static unsigned short chip_addr;
module_param(chip_addr, ushort, S_IRUGO);
MODULE_PARM_DESC(chip_addr, "Chip address (between 0x03 and 0x77)\n");
#define MAX_CHIPS 10
static u8 stub_pointer;
static u8 stub_bytes[256];
static u16 stub_words[256];
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;
u8 bytes[256];
u16 words[256];
};
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;
if (addr != chip_addr)
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) {
......@@ -53,12 +70,12 @@ static s32 stub_xfer(struct i2c_adapter * adap, u16 addr, unsigned short flags,
case I2C_SMBUS_BYTE:
if (read_write == I2C_SMBUS_WRITE) {
stub_pointer = command;
chip->pointer = command;
dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, "
"wrote 0x%02x.\n",
addr, command);
} else {
data->byte = stub_bytes[stub_pointer++];
data->byte = chip->bytes[chip->pointer++];
dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, "
"read 0x%02x.\n",
addr, data->byte);
......@@ -69,29 +86,29 @@ static s32 stub_xfer(struct i2c_adapter * adap, u16 addr, unsigned short flags,
case I2C_SMBUS_BYTE_DATA:
if (read_write == I2C_SMBUS_WRITE) {
stub_bytes[command] = data->byte;
chip->bytes[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 = stub_bytes[command];
data->byte = chip->bytes[command];
dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, "
"read 0x%02x at 0x%02x.\n",
addr, data->byte, command);
}
stub_pointer = command + 1;
chip->pointer = command + 1;
ret = 0;
break;
case I2C_SMBUS_WORD_DATA:
if (read_write == I2C_SMBUS_WRITE) {
stub_words[command] = data->word;
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 = stub_words[command];
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);
......@@ -129,23 +146,41 @@ static struct i2c_adapter stub_adapter = {
static int __init i2c_stub_init(void)
{
if (!chip_addr) {
int i, ret;
if (!chip_addr[0]) {
printk(KERN_ERR "i2c-stub: Please specify a chip address\n");
return -ENODEV;
}
if (chip_addr < 0x03 || chip_addr > 0x77) {
printk(KERN_ERR "i2c-stub: Invalid chip address 0x%02x\n",
chip_addr);
return -EINVAL;
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]);
}
printk(KERN_INFO "i2c-stub: Virtual chip at 0x%02x\n", chip_addr);
return i2c_add_adapter(&stub_adapter);
/* 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>");
......
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