On Sun, 22 Nov 2020 at 09:11, Dario Binacchi dariobin@libero.it wrote:
The __of_translate_address routine translates an address from the device tree into a CPU physical address. A note in the description of the routine explains that the crossing of any level with #size-cells = <0> is to be considered an error not by specification but since inherited from IBM. This does not happen for Texas Instruments, or at least for the beaglebone device tree. Without this patch, in fact, the translation into physical addresses of the registers contained in the am33xx-clocks.dtsi nodes would not be possible. They all have a parent with #size-cells = <0>.
The CONFIG_OF_TRANSLATE_ZERO_SIZE_CELLS symbol makes translation possible even in the case of crossing levels with #size-cells = <0>.
The patch acts conservatively on address translation, except for removing a check within the of_translate_one function in the drivers/core/of_addr.c file:
ranges = of_get_property(parent, rprop, &rlen);
if (ranges == NULL && !of_empty_ranges_quirk(parent)) {debug("no ranges; cannot translate\n");return 1;} if (ranges == NULL || rlen == 0) { offset = of_read_number(addr, na); memset(addr, 0, pna * 4); debug("empty ranges; 1:1 translation\n");There are two reasons: 1 The function of_empty_ranges_quirk always returns false, invalidating the following if statement in case of null ranges. Therefore one of the two checks is useless.
2 The implementation of the of_translate_one function found in the common/fdt_support.c file has removed this check while keeping the one about the 1:1 translation.
The patch adds a test and modifies a check for the correctness of an address in the case of enabling translation also for zero size cells. The added test checks translations of addresses generated by nodes of a device tree similar to those you can find in the files am33xx.dtsi and am33xx-clocks.dtsi for which the patch was created.
The patch was also tested on a beaglebone black board. The addresses generated for the registers of the loaded drivers are those specified by the AM335x reference manual.
Signed-off-by: Dario Binacchi dariobin@libero.it Tested-by: Dario Binacchi dariobin@libero.it Reviewed-by: Simon Glass sjg@chromium.org
(no changes since v4)
Changes in v4:
- Add Sphinx documentation for dm_flags.
- Convert GD_DM_FLG_* to enum.
- Include device_compat.h header in test/dm/test-fdt.c for dev_xxx macros.
Changes in v3:
- Comment dm_flags field in the global_data structure.
Changes in v2:
- Fix a missing line in the commit message.
- Add dm_flags to global_data structure and GD_DM_FLG_SIZE_CELLS_0 macro to test without recompiling.
- Update the OF_CHECK_COUNTS macro in order to have just one #define by bringing the GD_DM_FLG_SIZE_CELLS_0 into the expression.
- Lower-case the 0xC019 hex number.
arch/sandbox/dts/test.dts | 21 ++++++++++ common/fdt_support.c | 6 ++- drivers/core/Kconfig | 12 ++++++ drivers/core/fdtaddr.c | 2 +- drivers/core/of_addr.c | 14 ++----- drivers/core/ofnode.c | 7 +++- drivers/core/root.c | 3 ++ include/asm-generic/global_data.h | 18 ++++++++ test/dm/test-fdt.c | 69 ++++++++++++++++++++++++++++++- 9 files changed, 136 insertions(+), 16 deletions(-)
Still looks good to me.