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dm: doc: update of-plat with new phandle support

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Update documentation to reflect the new phandle support when OF_PLATDATA
is used. Now phandles are implemented as pointers to U_BOOT_DEVICE,
which makes it possible to get a pointer to the actual device.

Signed-off-by: Walter Lozano <walter.lozano@collabora.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Walter Lozano 2020-06-25 01:10:14 -03:00 committed by Simon Glass
parent 51f1263d89
commit cbd484f0eb
1 changed files with 16 additions and 8 deletions
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24
doc/driver-model/of-plat.rst
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@ -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:
@ -329,7 +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.