diff options
Diffstat (limited to 'doc/driver-model/of-plat.rst')
| -rw-r--r-- | doc/driver-model/of-plat.rst | 32 |
1 files changed, 14 insertions, 18 deletions
diff --git a/doc/driver-model/of-plat.rst b/doc/driver-model/of-plat.rst index afa27c211c..4ef2fe699a 100644 --- a/doc/driver-model/of-plat.rst +++ b/doc/driver-model/of-plat.rst @@ -21,7 +21,7 @@ SoCs require a 16KB SPL image which must include a full MMC stack. In this case the overhead of device tree access may be too great. It is possible to create platform data manually by defining C structures -for it, and reference that data in a U_BOOT_DEVICE() declaration. This +for it, and reference that data in a U_BOOT_DRVINFO() declaration. This bypasses the use of device tree completely, effectively creating a parallel configuration mechanism. But it is an available option for SPL. @@ -79,7 +79,7 @@ SPL/TPL and should be tested with: A new tool called 'dtoc' converts a device tree file either into a set of struct declarations, one for each compatible node, and a set of -U_BOOT_DEVICE() declarations along with the actual platform data for each +U_BOOT_DRVINFO() declarations along with the actual platform data for each device. As an example, consider this MMC node: .. code-block:: none @@ -155,16 +155,13 @@ and the following device declarations: .card_detect_delay = 0xc8, }; - U_BOOT_DEVICE(dwmmc_at_ff0c0000) = { + U_BOOT_DRVINFO(dwmmc_at_ff0c0000) = { .name = "rockchip_rk3288_dw_mshc", .plat = &dtv_dwmmc_at_ff0c0000, .plat_size = sizeof(dtv_dwmmc_at_ff0c0000), .parent_idx = -1, }; - void dm_populate_phandle_data(void) { - } - The device is then instantiated at run-time and the platform data can be accessed using: @@ -178,24 +175,21 @@ platform data in the driver. The of_to_plat() method should therefore do nothing in such a driver. Note that for the platform data to be matched with a driver, the 'name' -property of the U_BOOT_DEVICE() declaration has to match a driver declared +property of the U_BOOT_DRVINFO() declaration has to match a driver declared via U_BOOT_DRIVER(). This effectively means that a U_BOOT_DRIVER() with a 'name' corresponding to the devicetree 'compatible' string (after converting it to a valid name for C) is needed, so a dedicated driver is required for each 'compatible' string. -In order to make this a bit more flexible U_BOOT_DRIVER_ALIAS macro can be +In order to make this a bit more flexible DM_DRIVER_ALIAS macro can be used to declare an alias for a driver name, typically a 'compatible' string. This macro produces no code, but it is by dtoc tool. The parent_idx is the index of the parent driver_info structure within its -linker list (instantiated by the U_BOOT_DEVICE() macro). This is used to support -dev_get_parent(). The dm_populate_phandle_data() is included to allow for -fix-ups required by dtoc. It is not currently used. The values in 'clocks' are -the index of the driver_info for the target device followed by any phandle -arguments. This is used to support device_get_by_driver_info_idx(). +linker list (instantiated by the U_BOOT_DRVINFO() macro). This is used to support +dev_get_parent(). -During the build process dtoc parses both U_BOOT_DRIVER and U_BOOT_DRIVER_ALIAS +During the build process dtoc parses both U_BOOT_DRIVER and DM_DRIVER_ALIAS to build a list of valid driver names and driver aliases. If the 'compatible' string used for a device does not not match a valid driver name, it will be checked against the list of driver aliases in order to get the right driver @@ -297,7 +291,7 @@ For example: .plat_auto = sizeof(struct mmc_plat), }; - U_BOOT_DRIVER_ALIAS(mmc_drv, vendor_mmc) /* matches compatible string */ + DM_DRIVER_ALIAS(mmc_drv, vendor_mmc) /* matches compatible string */ Note that struct mmc_plat is defined in the C file, not in a header. This is to avoid needing to include dt-structs.h in a header file. The idea is to @@ -337,9 +331,11 @@ prevents them being used inadvertently. All usage must be bracketed with #if CONFIG_IS_ENABLED(OF_PLATDATA). The dt-plat.c file contains the device declarations and is is built in -spl/dt-plat.c. It additionally contains the definition of -dm_populate_phandle_data() which is responsible of filling the phandle -information by adding references to U_BOOT_DEVICE by using DM_GET_DEVICE +spl/dt-plat.c. + +The dm_populate_phandle_data() function that was previous needed has now been +removed, since dtoc can address the drivers directly from dt-plat.c and does +not need to fix up things at runtime. The pylibfdt Python module is used to access the devicetree. |