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authorJean Delvare <khali@linux-fr.org>2008-07-14 22:38:36 +0200
committerJean Delvare <khali@mahadeva.delvare>2008-07-14 22:38:36 +0200
commit4735c98f8447acb1c8977e2b8024640f7bf36dd6 (patch)
tree7f7c65b1feef6a0213caa20218cd6080488cc62b
parent8508159e2f3b82bf109f0ec77bcbd8ff3f3a7e17 (diff)
i2c: Add detection capability to new-style drivers
Add a mechanism to let new-style i2c drivers optionally autodetect devices they would support on selected buses and ask i2c-core to instantiate them. This is a replacement for legacy i2c drivers, much cleaner. Where drivers had to implement both a legacy i2c_driver and a new-style i2c_driver so far, this mechanism makes it possible to get rid of the legacy i2c_driver and implement both enumerated and detected device support with just one (new-style) i2c_driver. Here is a quick conversion guide for these drivers, step by step: * Delete the legacy driver definition, registration and removal. Delete the attach_adapter and detach_client methods of the legacy driver. * Change the prototype of the legacy detect function from static int foo_detect(struct i2c_adapter *adapter, int address, int kind); to static int foo_detect(struct i2c_client *client, int kind, struct i2c_board_info *info); * Set the new-style driver detect callback to this new function, and set its address_data to &addr_data (addr_data is generally provided by I2C_CLIENT_INSMOD.) * Add the appropriate class to the new-style driver. This is typically the class the legacy attach_adapter method was checking for. Class checking is now mandatory (done by i2c-core.) See <linux/i2c.h> for the list of available classes. * Remove the i2c_client allocation and freeing from the detect function. A pre-allocated client is now handed to you by i2c-core, and is freed automatically. * Make the detect function fill the type field of the i2c_board_info structure it was passed as a parameter, and return 0, on success. If the detection fails, return -ENODEV. Signed-off-by: Jean Delvare <khali@linux-fr.org>
-rw-r--r--Documentation/i2c/writing-clients29
-rw-r--r--drivers/i2c/i2c-core.c223
-rw-r--r--include/linux/i2c.h36
3 files changed, 272 insertions, 16 deletions
diff --git a/Documentation/i2c/writing-clients b/Documentation/i2c/writing-clients
index 63722d3c9cdf..6b61b3a2e90b 100644
--- a/Documentation/i2c/writing-clients
+++ b/Documentation/i2c/writing-clients
@@ -44,6 +44,10 @@ static struct i2c_driver foo_driver = {
.id_table = foo_ids,
.probe = foo_probe,
.remove = foo_remove,
+ /* if device autodetection is needed: */
+ .class = I2C_CLASS_SOMETHING,
+ .detect = foo_detect,
+ .address_data = &addr_data,
/* else, driver uses "legacy" binding model: */
.attach_adapter = foo_attach_adapter,
@@ -217,6 +221,31 @@ in the I2C bus driver. You may want to save the returned i2c_client
reference for later use.
+Device Detection (Standard driver model)
+----------------------------------------
+
+Sometimes you do not know in advance which I2C devices are connected to
+a given I2C bus. This is for example the case of hardware monitoring
+devices on a PC's SMBus. In that case, you may want to let your driver
+detect supported devices automatically. This is how the legacy model
+was working, and is now available as an extension to the standard
+driver model (so that we can finally get rid of the legacy model.)
+
+You simply have to define a detect callback which will attempt to
+identify supported devices (returning 0 for supported ones and -ENODEV
+for unsupported ones), a list of addresses to probe, and a device type
+(or class) so that only I2C buses which may have that type of device
+connected (and not otherwise enumerated) will be probed. The i2c
+core will then call you back as needed and will instantiate a device
+for you for every successful detection.
+
+Note that this mechanism is purely optional and not suitable for all
+devices. You need some reliable way to identify the supported devices
+(typically using device-specific, dedicated identification registers),
+otherwise misdetections are likely to occur and things can get wrong
+quickly.
+
+
Device Deletion (Standard driver model)
---------------------------------------
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 5e249d758828..0a79f7661017 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -42,7 +42,9 @@
static DEFINE_MUTEX(core_lock);
static DEFINE_IDR(i2c_adapter_idr);
-#define is_newstyle_driver(d) ((d)->probe || (d)->remove)
+#define is_newstyle_driver(d) ((d)->probe || (d)->remove || (d)->detect)
+
+static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver);
/* ------------------------------------------------------------------------- */
@@ -418,6 +420,10 @@ static int i2c_do_add_adapter(struct device_driver *d, void *data)
struct i2c_driver *driver = to_i2c_driver(d);
struct i2c_adapter *adap = data;
+ /* Detect supported devices on that bus, and instantiate them */
+ i2c_detect(adap, driver);
+
+ /* Let legacy drivers scan this bus for matching devices */
if (driver->attach_adapter) {
/* We ignore the return code; if it fails, too bad */
driver->attach_adapter(adap);
@@ -457,7 +463,7 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
if (adap->nr < __i2c_first_dynamic_bus_num)
i2c_scan_static_board_info(adap);
- /* let legacy drivers scan this bus for matching devices */
+ /* Notify drivers */
dummy = bus_for_each_drv(&i2c_bus_type, NULL, adap,
i2c_do_add_adapter);
@@ -563,8 +569,19 @@ static int i2c_do_del_adapter(struct device_driver *d, void *data)
{
struct i2c_driver *driver = to_i2c_driver(d);
struct i2c_adapter *adapter = data;
+ struct i2c_client *client, *_n;
int res;
+ /* Remove the devices we created ourselves */
+ list_for_each_entry_safe(client, _n, &driver->clients, detected) {
+ if (client->adapter == adapter) {
+ dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
+ client->name, client->addr);
+ list_del(&client->detected);
+ i2c_unregister_device(client);
+ }
+ }
+
if (!driver->detach_adapter)
return 0;
res = driver->detach_adapter(adapter);
@@ -651,7 +668,11 @@ static int __attach_adapter(struct device *dev, void *data)
struct i2c_adapter *adapter = to_i2c_adapter(dev);
struct i2c_driver *driver = data;
- driver->attach_adapter(adapter);
+ i2c_detect(adapter, driver);
+
+ /* Legacy drivers scan i2c busses directly */
+ if (driver->attach_adapter)
+ driver->attach_adapter(adapter);
return 0;
}
@@ -695,10 +716,9 @@ int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
pr_debug("i2c-core: driver [%s] registered\n", driver->driver.name);
- /* legacy drivers scan i2c busses directly */
- if (driver->attach_adapter)
- class_for_each_device(&i2c_adapter_class, driver,
- __attach_adapter);
+ INIT_LIST_HEAD(&driver->clients);
+ /* Walk the adapters that are already present */
+ class_for_each_device(&i2c_adapter_class, driver, __attach_adapter);
mutex_unlock(&core_lock);
return 0;
@@ -709,6 +729,17 @@ static int __detach_adapter(struct device *dev, void *data)
{
struct i2c_adapter *adapter = to_i2c_adapter(dev);
struct i2c_driver *driver = data;
+ struct i2c_client *client, *_n;
+
+ list_for_each_entry_safe(client, _n, &driver->clients, detected) {
+ dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
+ client->name, client->addr);
+ list_del(&client->detected);
+ i2c_unregister_device(client);
+ }
+
+ if (is_newstyle_driver(driver))
+ return 0;
/* Have a look at each adapter, if clients of this driver are still
* attached. If so, detach them to be able to kill the driver
@@ -747,10 +778,7 @@ void i2c_del_driver(struct i2c_driver *driver)
{
mutex_lock(&core_lock);
- /* legacy driver? */
- if (!is_newstyle_driver(driver))
- class_for_each_device(&i2c_adapter_class, driver,
- __detach_adapter);
+ class_for_each_device(&i2c_adapter_class, driver, __detach_adapter);
driver_unregister(&driver->driver);
pr_debug("i2c-core: driver [%s] unregistered\n", driver->driver.name);
@@ -1205,6 +1233,179 @@ int i2c_probe(struct i2c_adapter *adapter,
}
EXPORT_SYMBOL(i2c_probe);
+/* Separate detection function for new-style drivers */
+static int i2c_detect_address(struct i2c_client *temp_client, int kind,
+ struct i2c_driver *driver)
+{
+ struct i2c_board_info info;
+ struct i2c_adapter *adapter = temp_client->adapter;
+ int addr = temp_client->addr;
+ int err;
+
+ /* Make sure the address is valid */
+ if (addr < 0x03 || addr > 0x77) {
+ dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n",
+ addr);
+ return -EINVAL;
+ }
+
+ /* Skip if already in use */
+ if (i2c_check_addr(adapter, addr))
+ return 0;
+
+ /* Make sure there is something at this address, unless forced */
+ if (kind < 0) {
+ if (i2c_smbus_xfer(adapter, addr, 0, 0, 0,
+ I2C_SMBUS_QUICK, NULL) < 0)
+ return 0;
+
+ /* prevent 24RF08 corruption */
+ if ((addr & ~0x0f) == 0x50)
+ i2c_smbus_xfer(adapter, addr, 0, 0, 0,
+ I2C_SMBUS_QUICK, NULL);
+ }
+
+ /* Finally call the custom detection function */
+ memset(&info, 0, sizeof(struct i2c_board_info));
+ info.addr = addr;
+ err = driver->detect(temp_client, kind, &info);
+ if (err) {
+ /* -ENODEV is returned if the detection fails. We catch it
+ here as this isn't an error. */
+ return err == -ENODEV ? 0 : err;
+ }
+
+ /* Consistency check */
+ if (info.type[0] == '\0') {
+ dev_err(&adapter->dev, "%s detection function provided "
+ "no name for 0x%x\n", driver->driver.name,
+ addr);
+ } else {
+ struct i2c_client *client;
+
+ /* Detection succeeded, instantiate the device */
+ dev_dbg(&adapter->dev, "Creating %s at 0x%02x\n",
+ info.type, info.addr);
+ client = i2c_new_device(adapter, &info);
+ if (client)
+ list_add_tail(&client->detected, &driver->clients);
+ else
+ dev_err(&adapter->dev, "Failed creating %s at 0x%02x\n",
+ info.type, info.addr);
+ }
+ return 0;
+}
+
+static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
+{
+ const struct i2c_client_address_data *address_data;
+ struct i2c_client *temp_client;
+ int i, err = 0;
+ int adap_id = i2c_adapter_id(adapter);
+
+ address_data = driver->address_data;
+ if (!driver->detect || !address_data)
+ return 0;
+
+ /* Set up a temporary client to help detect callback */
+ temp_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
+ if (!temp_client)
+ return -ENOMEM;
+ temp_client->adapter = adapter;
+
+ /* Force entries are done first, and are not affected by ignore
+ entries */
+ if (address_data->forces) {
+ const unsigned short * const *forces = address_data->forces;
+ int kind;
+
+ for (kind = 0; forces[kind]; kind++) {
+ for (i = 0; forces[kind][i] != I2C_CLIENT_END;
+ i += 2) {
+ if (forces[kind][i] == adap_id
+ || forces[kind][i] == ANY_I2C_BUS) {
+ dev_dbg(&adapter->dev, "found force "
+ "parameter for adapter %d, "
+ "addr 0x%02x, kind %d\n",
+ adap_id, forces[kind][i + 1],
+ kind);
+ temp_client->addr = forces[kind][i + 1];
+ err = i2c_detect_address(temp_client,
+ kind, driver);
+ if (err)
+ goto exit_free;
+ }
+ }
+ }
+ }
+
+ /* Stop here if we can't use SMBUS_QUICK */
+ if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_QUICK)) {
+ if (address_data->probe[0] == I2C_CLIENT_END
+ && address_data->normal_i2c[0] == I2C_CLIENT_END)
+ goto exit_free;
+
+ dev_warn(&adapter->dev, "SMBus Quick command not supported, "
+ "can't probe for chips\n");
+ err = -EOPNOTSUPP;
+ goto exit_free;
+ }
+
+ /* Stop here if the classes do not match */
+ if (!(adapter->class & driver->class))
+ goto exit_free;
+
+ /* Probe entries are done second, and are not affected by ignore
+ entries either */
+ for (i = 0; address_data->probe[i] != I2C_CLIENT_END; i += 2) {
+ if (address_data->probe[i] == adap_id
+ || address_data->probe[i] == ANY_I2C_BUS) {
+ dev_dbg(&adapter->dev, "found probe parameter for "
+ "adapter %d, addr 0x%02x\n", adap_id,
+ address_data->probe[i + 1]);
+ temp_client->addr = address_data->probe[i + 1];
+ err = i2c_detect_address(temp_client, -1, driver);
+ if (err)
+ goto exit_free;
+ }
+ }
+
+ /* Normal entries are done last, unless shadowed by an ignore entry */
+ for (i = 0; address_data->normal_i2c[i] != I2C_CLIENT_END; i += 1) {
+ int j, ignore;
+
+ ignore = 0;
+ for (j = 0; address_data->ignore[j] != I2C_CLIENT_END;
+ j += 2) {
+ if ((address_data->ignore[j] == adap_id ||
+ address_data->ignore[j] == ANY_I2C_BUS)
+ && address_data->ignore[j + 1]
+ == address_data->normal_i2c[i]) {
+ dev_dbg(&adapter->dev, "found ignore "
+ "parameter for adapter %d, "
+ "addr 0x%02x\n", adap_id,
+ address_data->ignore[j + 1]);
+ ignore = 1;
+ break;
+ }
+ }
+ if (ignore)
+ continue;
+
+ dev_dbg(&adapter->dev, "found normal entry for adapter %d, "
+ "addr 0x%02x\n", adap_id,
+ address_data->normal_i2c[i]);
+ temp_client->addr = address_data->normal_i2c[i];
+ err = i2c_detect_address(temp_client, -1, driver);
+ if (err)
+ goto exit_free;
+ }
+
+ exit_free:
+ kfree(temp_client);
+ return err;
+}
+
struct i2c_client *
i2c_new_probed_device(struct i2c_adapter *adap,
struct i2c_board_info *info,
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 50cbab4b62b0..08be0d21864c 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -45,6 +45,7 @@ struct i2c_adapter;
struct i2c_client;
struct i2c_driver;
union i2c_smbus_data;
+struct i2c_board_info;
/*
* The master routines are the ones normally used to transmit data to devices
@@ -94,15 +95,33 @@ extern s32 i2c_smbus_write_i2c_block_data(struct i2c_client * client,
u8 command, u8 length,
const u8 *values);
-/*
- * A driver is capable of handling one or more physical devices present on
- * I2C adapters. This information is used to inform the driver of adapter
- * events.
+/**
+ * struct i2c_driver - represent an I2C device driver
+ * @class: What kind of i2c device we instantiate (for detect)
+ * @detect: Callback for device detection
+ * @address_data: The I2C addresses to probe, ignore or force (for detect)
+ * @clients: List of detected clients we created (for i2c-core use only)
*
* The driver.owner field should be set to the module owner of this driver.
* The driver.name field should be set to the name of this driver.
+ *
+ * For automatic device detection, both @detect and @address_data must
+ * be defined. @class should also be set, otherwise only devices forced
+ * with module parameters will be created. The detect function must
+ * fill at least the name field of the i2c_board_info structure it is
+ * handed upon successful detection, and possibly also the flags field.
+ *
+ * If @detect is missing, the driver will still work fine for enumerated
+ * devices. Detected devices simply won't be supported. This is expected
+ * for the many I2C/SMBus devices which can't be detected reliably, and
+ * the ones which can always be enumerated in practice.
+ *
+ * The i2c_client structure which is handed to the @detect callback is
+ * not a real i2c_client. It is initialized just enough so that you can
+ * call i2c_smbus_read_byte_data and friends on it. Don't do anything
+ * else with it. In particular, calling dev_dbg and friends on it is
+ * not allowed.
*/
-
struct i2c_driver {
int id;
unsigned int class;
@@ -142,6 +161,11 @@ struct i2c_driver {
struct device_driver driver;
const struct i2c_device_id *id_table;
+
+ /* Device detection callback for automatic device creation */
+ int (*detect)(struct i2c_client *, int kind, struct i2c_board_info *);
+ const struct i2c_client_address_data *address_data;
+ struct list_head clients;
};
#define to_i2c_driver(d) container_of(d, struct i2c_driver, driver)
@@ -157,6 +181,7 @@ struct i2c_driver {
* @dev: Driver model device node for the slave.
* @irq: indicates the IRQ generated by this device (if any)
* @list: list of active/busy clients (DEPRECATED)
+ * @detected: member of an i2c_driver.clients list
* @released: used to synchronize client releases & detaches and references
*
* An i2c_client identifies a single device (i.e. chip) connected to an
@@ -174,6 +199,7 @@ struct i2c_client {
struct device dev; /* the device structure */
int irq; /* irq issued by device */
struct list_head list; /* DEPRECATED */
+ struct list_head detected;
struct completion released;
};
#define to_i2c_client(d) container_of(d, struct i2c_client, dev)