i2c-stub: Chip address as a module parameter

i2c-stub: Chip address as a module parameter

Add a mandatory chip_addr parameter to i2c-stub. This parameter
defines to which chip address the driver will respond, instead of
reponding to all addresses as before. The idea is to prevent the
users from loading i2c-stub at random and being then confused by
the results of sensors-detect or other user-space tools.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 18 insertions, 1 deletions

diff --git a/drivers/i2c/busses/i2c-stub.c b/drivers/i2c/busses/i2c-stub.c
index 73f481e93a36..8cf374ddd989 100644
--- a/drivers/i2c/busses/i2c-stub.c
+++ b/drivers/i2c/busses/i2c-stub.c
@@ -27,6 +27,10 @@
 #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");
+
 static u8  stub_pointer;
 static u8  stub_bytes[256];
 static u16 stub_words[256];
@@ -37,6 +41,9 @@ static s32 stub_xfer(struct i2c_adapter * adap, u16 addr, unsigned short flags,
 {
         s32 ret;
 
+        if (addr != chip_addr)
+                return -ENODEV;
+
         switch (size) {
 
         case I2C_SMBUS_QUICK:
@@ -122,7 +129,17 @@ static struct i2c_adapter stub_adapter = {
 
 static int __init i2c_stub_init(void)
 {
-        printk(KERN_INFO "i2c-stub loaded\n");
+        if (!chip_addr) {
+                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;
+        }
+
+        printk(KERN_INFO "i2c-stub: Virtual chip at 0x%02x\n", chip_addr);
         return i2c_add_adapter(&stub_adapter);
 }