diff options
| -rw-r--r-- | Documentation/i2c/writing-clients | 29 | ||||
| -rw-r--r-- | drivers/i2c/i2c-core.c | 223 | ||||
| -rw-r--r-- | include/linux/i2c.h | 36 |
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) |