From: Michael Lawnick <ml.lawnick@xxxxxx>
After system startup currently there is no way to add an i2c client to
subsystem. This may occur if the client sits on a subsystem that was
powerless at the beginning or is plugged in at runtime.
This patch adds ioctl to /dev/i2c-X to initiate a probe of an client and
to remove a client that may have gone.
Example:
fd=open("/dev/i2c-1",O_RDWR);
ioctl(fd,I2C_PROBE,"lm75,0x49");
close(fd);
will start probing of an lm75 compatible sensor at bus 1, id 0x49
ioctl(fd,I2C_REMOVE,0x49)
removes it again.
Signed-off-by: Michael Lawnick <ml.lawnick@xxxxxx>
---
Add ioctls I2C_PROBE and I2C_REMOVE to /dev/i2c-x
drivers/i2c/i2c-dev.c | 50
++++++++++++++++++++++++++++++++++++++++++++++-
include/linux/i2c-dev.h | 2 +
2 files changed, 51 insertions(+), 1 deletions(-)
diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index c171988..82cbe7f
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -367,9 +367,22 @@ static noinline int i2cdev_ioctl_smbus(struct
i2c_client *client,
return res;
}
+static int i2c_check_addr(struct device *dev, void *addrp)
+{
+ struct i2c_client *client = i2c_verify_client(dev);
+ int addr = *(int *)addrp;
+
+ if (client && client->addr == addr)
+ return -EBUSY;
+ return 0;
+}
+
static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned
long arg)
{
- struct i2c_client *client = (struct i2c_client *)file->private_data;
+ struct i2c_client *bus_client, *client = (struct i2c_client
*)file->private_data;
+ struct i2c_board_info bInfo;
+ struct device *dev;
+ char *colon, request[I2C_NAME_SIZE + 5];
unsigned long funcs;
dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
@@ -424,6 +437,41 @@ static long i2cdev_ioctl(struct file *file,
unsigned int cmd, unsigned long arg)
case I2C_TIMEOUT:
client->adapter->timeout = arg;
break;
+ case I2C_PROBE:
+ memset(&bInfo, 0, sizeof(bInfo));
+ copy_from_user(request, (char *)arg, sizeof(request));
+
+ colon = strchr(request, ',');
+ if((!colon) || (colon - request > I2C_NAME_SIZE - 1))
+ return -EINVAL;
+
+ strncpy(bInfo.type, request, colon - request);
+ bInfo.type[I2C_NAME_SIZE - 1] = '\0';
+ bInfo.addr = simple_strtoul(colon + 1, NULL, 0);
+
+ bus_client = i2c_new_device(client->adapter, &bInfo);
+
+ if(!bus_client)
+ return -EIO;
+
+ if(!bus_client->driver)
+ {
+ /* probe failed -> cleanup */
+ i2c_unregister_device(bus_client);
+ return -ENODEV;
+ }
+ break;
+ case I2C_REMOVE:
+ dev = device_find_child(&client->adapter->dev, &arg, i2c_check_addr);
+ if (!dev)
+ return -ENODEV;
+
+ bus_client = i2c_verify_client(dev);
+ if(!bus_client)
+ return -EIO;
+
+ i2c_unregister_device(bus_client);
+ break;
default:
/* NOTE: returning a fault code here could cause trouble
* in buggy userspace code. Some old kernel bugs returned
diff --git a/include/linux/i2c-dev.h b/include/linux/i2c-dev.h
index 311315b..8b66638
--- a/include/linux/i2c-dev.h
+++ b/include/linux/i2c-dev.h
@@ -50,6 +50,8 @@
#define I2C_PEC 0x0708 /* != 0 to use PEC with SMBus */
#define I2C_SMBUS 0x0720 /* SMBus transfer */
+#define I2C_PROBE 0x0730 /* Probe for client "<name>,<addr>" */
+#define I2C_REMOVE 0x0731 /* Remove client <addr> */
/* This is the structure as used in the I2C_SMBUS ioctl call */
struct i2c_smbus_ioctl_data {
--
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