Update this to incorporate the parent feature as well as other recent developments.
Signed-off-by: Simon Glass sjg@chromium.org ---
doc/driver-model/of-plat.rst | 42 ++++++++++++++++-------------------- 1 file changed, 19 insertions(+), 23 deletions(-)
diff --git a/doc/driver-model/of-plat.rst b/doc/driver-model/of-plat.rst index 1e3fad137be..58481665cec 100644 --- a/doc/driver-model/of-plat.rst +++ b/doc/driver-model/of-plat.rst @@ -66,12 +66,6 @@ strictly necessary. Notable problems include: normally also supports device tree it must use #ifdef to separate out this code, since the structures are only available in SPL.
- - 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 struct driver_info. This pointer can be used to access - the referenced device. -
How it works ------------ @@ -134,10 +128,14 @@ the following C struct declaration: fdt32_t vmmc_supply; };
-and the following device declaration: +and the following device declarations:
.. code-block:: c
+ /* Node /clock-controller@ff760000 index 0 */ + ... + + /* Node /dwmmc@ff0c0000 index 2 */ static struct dtd_rockchip_rk3288_dw_mshc dtv_dwmmc_at_ff0c0000 = { .fifo_depth = 0x100, .cap_sd_highspeed = true, @@ -145,10 +143,10 @@ and the following device declaration: .clock_freq_min_max = {0x61a80, 0x8f0d180}, .vmmc_supply = 0xb, .num_slots = 0x1, - .clocks = {{NULL, 456}, - {NULL, 68}, - {NULL, 114}, - {NULL, 118}}, + .clocks = {{0, 456}, + {0, 68}, + {0, 114}, + {0, 118}}, .cap_mmc_highspeed = true, .disable_wp = true, .bus_width = 0x4, @@ -161,13 +159,10 @@ and the following device declaration: .name = "rockchip_rk3288_dw_mshc", .platdata = &dtv_dwmmc_at_ff0c0000, .platdata_size = sizeof(dtv_dwmmc_at_ff0c0000), + .parent_idx = -1, };
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 @@ -193,6 +188,13 @@ 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.
+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(). + 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 @@ -339,12 +341,7 @@ 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. - -The 'swig' tool is needed to build the libfdt Python module. If this is not -found then the Python model is not used and a fallback is used instead, which -makes use of fdtget. +The pylibfdt Python module is used to access the devicetree.
Credits @@ -357,11 +354,10 @@ Future work ----------- - Consider programmatically reading binding files instead of device tree contents -- Complete the phandle feature -- Move to using a full Python libfdt module
.. Simon Glass sjg@chromium.org .. Google, Inc .. 6/6/16 .. Updated Independence Day 2016 +.. Updated 1st October 2020