summaryrefslogtreecommitdiff
path: root/drivers/i2c/i2c-stub.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/i2c/i2c-stub.c')
-rw-r--r--drivers/i2c/i2c-stub.c220
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 0000000..d0a9c59
--- /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);