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 000000000000..d0a9c590c3cd
--- /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);