diff options
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/i2c-core.c | 74 |
1 files changed, 59 insertions, 15 deletions
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index abe41369eec1..347494a8750e 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -105,11 +105,13 @@ struct gsb_buffer { struct i2c_acpi_lookup { struct i2c_board_info *info; + struct i2c_adapter *adapter; /* set only when registering slaves */ acpi_handle adapter_handle; acpi_handle device_handle; + u32 min_speed; }; -static int i2c_acpi_find_address(struct acpi_resource *ares, void *data) +static int i2c_acpi_find_resource(struct acpi_resource *ares, void *data) { struct i2c_acpi_lookup *lookup = data; struct i2c_board_info *info = lookup->info; @@ -135,17 +137,20 @@ static int i2c_acpi_find_address(struct acpi_resource *ares, void *data) info->addr = sb->slave_address; if (sb->access_mode == ACPI_I2C_10BIT_MODE) info->flags |= I2C_CLIENT_TEN; + /* Save speed of the slowest device */ + if (sb->connection_speed < lookup->min_speed) + lookup->min_speed = sb->connection_speed; } return 1; } -static acpi_status i2c_acpi_add_device(acpi_handle handle, u32 level, - void *data, void **return_value) +static acpi_status i2c_acpi_slave_lookup(acpi_handle handle, u32 level, + void *data, void **return_value) { - struct i2c_adapter *adapter = data; + struct i2c_acpi_lookup *lookup = data; + struct i2c_adapter *adapter = lookup->adapter; struct list_head resource_list; - struct i2c_acpi_lookup lookup; struct resource_entry *entry; struct i2c_board_info info; struct acpi_device *adev; @@ -159,10 +164,8 @@ static acpi_status i2c_acpi_add_device(acpi_handle handle, u32 level, memset(&info, 0, sizeof(info)); info.fwnode = acpi_fwnode_handle(adev); - memset(&lookup, 0, sizeof(lookup)); - lookup.adapter_handle = ACPI_HANDLE(&adapter->dev); - lookup.device_handle = handle; - lookup.info = &info; + lookup->device_handle = handle; + lookup->info = &info; /* * Look up for I2cSerialBus resource with ResourceSource that @@ -170,10 +173,10 @@ static acpi_status i2c_acpi_add_device(acpi_handle handle, u32 level, */ INIT_LIST_HEAD(&resource_list); ret = acpi_dev_get_resources(adev, &resource_list, - i2c_acpi_find_address, &lookup); + i2c_acpi_find_resource, lookup); acpi_dev_free_resource_list(&resource_list); - if (ret < 0 || !info.addr) + if (ret < 0 || !info.addr || !lookup->adapter) return AE_OK; /* Then fill IRQ number if any */ @@ -204,6 +207,14 @@ static acpi_status i2c_acpi_add_device(acpi_handle handle, u32 level, #define I2C_ACPI_MAX_SCAN_DEPTH 32 +static acpi_status i2c_acpi_walk(struct i2c_acpi_lookup *lookup) +{ + return acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT, + I2C_ACPI_MAX_SCAN_DEPTH, + i2c_acpi_slave_lookup, NULL, + lookup, NULL); +} + /** * i2c_acpi_register_devices - enumerate I2C slave devices behind adapter * @adap: pointer to adapter @@ -214,19 +225,52 @@ static acpi_status i2c_acpi_add_device(acpi_handle handle, u32 level, */ static void i2c_acpi_register_devices(struct i2c_adapter *adap) { + struct i2c_acpi_lookup lookup; acpi_status status; if (!has_acpi_companion(&adap->dev)) return; - status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT, - I2C_ACPI_MAX_SCAN_DEPTH, - i2c_acpi_add_device, NULL, - adap, NULL); + memset(&lookup, 0, sizeof(lookup)); + lookup.adapter = adap; + lookup.adapter_handle = ACPI_HANDLE(&adap->dev); + + status = i2c_acpi_walk(&lookup); if (ACPI_FAILURE(status)) dev_warn(&adap->dev, "failed to enumerate I2C slaves\n"); } +/** + * i2c_acpi_find_bus_speed - find I2C bus speed from ACPI + * @dev: The device owning the bus + * + * Find the I2C bus speed by walking the ACPI namespace for all I2C slaves + * devices connected to this bus and use the speed of slowest device. + * + * Returns the speed in Hz or zero + */ +u32 i2c_acpi_find_bus_speed(struct device *dev) +{ + struct i2c_acpi_lookup lookup; + acpi_status status; + + if (!has_acpi_companion(dev)) + return 0; + + memset(&lookup, 0, sizeof(lookup)); + lookup.adapter_handle = ACPI_HANDLE(dev); + lookup.min_speed = UINT_MAX; + + status = i2c_acpi_walk(&lookup); + if (ACPI_FAILURE(status)) { + dev_warn(dev, "unable to find I2C bus speed from ACPI\n"); + return 0; + } + + return lookup.min_speed != UINT_MAX ? lookup.min_speed : 0; +} +EXPORT_SYMBOL_GPL(i2c_acpi_find_bus_speed); + #else /* CONFIG_ACPI */ static inline void i2c_acpi_register_devices(struct i2c_adapter *adap) { } #endif /* CONFIG_ACPI */ |