diff options
Diffstat (limited to 'doc/driver-model/of-plat.rst')
| -rw-r--r-- | doc/driver-model/of-plat.rst | 38 |
1 files changed, 29 insertions, 9 deletions
diff --git a/doc/driver-model/of-plat.rst b/doc/driver-model/of-plat.rst index 034a68bb4e..1e3fad137b 100644 --- a/doc/driver-model/of-plat.rst +++ b/doc/driver-model/of-plat.rst @@ -69,9 +69,8 @@ strictly necessary. Notable problems include: - Correct relations between nodes are not implemented. This means that parent/child relations (like bus device iteration) do not work yet. Some phandles (those that are recognised as such) are converted into - a pointer to platform data. This pointer can potentially be used to - access the referenced device (by searching for the pointer value). - This feature is not yet implemented, however. + a pointer to struct driver_info. This pointer can be used to access + the referenced device. How it works @@ -146,10 +145,10 @@ and the following device declaration: .clock_freq_min_max = {0x61a80, 0x8f0d180}, .vmmc_supply = 0xb, .num_slots = 0x1, - .clocks = {{&dtv_clock_controller_at_ff760000, 456}, - {&dtv_clock_controller_at_ff760000, 68}, - {&dtv_clock_controller_at_ff760000, 114}, - {&dtv_clock_controller_at_ff760000, 118}}, + .clocks = {{NULL, 456}, + {NULL, 68}, + {NULL, 114}, + {NULL, 118}}, .cap_mmc_highspeed = true, .disable_wp = true, .bus_width = 0x4, @@ -164,6 +163,13 @@ and the following device declaration: .platdata_size = sizeof(dtv_dwmmc_at_ff0c0000), }; + void dm_populate_phandle_data(void) { + dtv_dwmmc_at_ff0c0000.clocks[0].node = DM_GET_DEVICE(clock_controller_at_ff760000); + dtv_dwmmc_at_ff0c0000.clocks[1].node = DM_GET_DEVICE(clock_controller_at_ff760000); + dtv_dwmmc_at_ff0c0000.clocks[2].node = DM_GET_DEVICE(clock_controller_at_ff760000); + dtv_dwmmc_at_ff0c0000.clocks[3].node = DM_GET_DEVICE(clock_controller_at_ff760000); + } + The device is then instantiated at run-time and the platform data can be accessed using: @@ -183,6 +189,17 @@ via U_BOOT_DRIVER(). This effectively means that a U_BOOT_DRIVER() with a 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 +used to declare an alias for a driver name, typically a 'compatible' string. +This macro produces no code, but it is by dtoc tool. + +During the build process dtoc parses both U_BOOT_DRIVER and U_BOOT_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 +name to use. If in this step there is no match found a warning is issued to +avoid run-time failures. + Where a node has multiple compatible strings, a #define is used to make them equivalent, e.g.: @@ -269,7 +286,7 @@ For example: }; U_BOOT_DRIVER(mmc_drv) = { - .name = "vendor_mmc", /* matches compatible string */ + .name = "mmc_drv", .id = UCLASS_MMC, .of_match = mmc_ids, .ofdata_to_platdata = mmc_ofdata_to_platdata, @@ -278,6 +295,7 @@ For example: .platdata_auto_alloc_size = sizeof(struct mmc_platdata), }; + U_BOOT_DRIVER_ALIAS(mmc_drv, vendor_mmc) /* matches compatible string */ Note that struct mmc_platdata 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 @@ -317,7 +335,9 @@ prevents them being used inadvertently. All usage must be bracketed with #if CONFIG_IS_ENABLED(OF_PLATDATA). The dt-platdata.c file contains the device declarations and is is built in -spl/dt-platdata.c. +spl/dt-platdata.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 The beginnings of a libfdt Python module are provided. So far this only implements a subset of the features. |