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 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.
-
How it works
------------
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,
.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 = {{0, 456},
+ {0, 68},
+ {0, 114},
+ {0, 118}},
.cap_mmc_highspeed = true,
.disable_wp = true,
.bus_width = 0x4,
.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) {
+ }
+
The device is then instantiated at run-time and the platform data can be
accessed using:
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.
+
+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
+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.:
};
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,
.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
+keep the use of each of-platdata struct to the smallest possible code area.
+There is just one driver C file for each struct, that can convert from the
+of-platdata struct to the standard one used by the driver.
In the case where SPL_OF_PLATDATA is enabled, platdata_auto_alloc_size is
still used to allocate space for the platform data. This is different from
#if CONFIG_IS_ENABLED(OF_PLATDATA).
The dt-platdata.c file contains the device declarations and is is built in
-spl/dt-platdata.c.
-
-The beginnings of a libfdt Python module are provided. So far this only
-implements a subset of the features.
+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 '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
-----------
- 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
projects / platform / kernel / u-boot.git / blobdiff