| Message ID | 20240621115544.1655458-1-peter.griffin@linaro.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | Add syscon of_syscon_register_regmap api | expand |
On Fri, Jun 21, 2024, at 11:55, Peter Griffin wrote: > Changes since v2: > - Move allocation outside spinlock area (Arnd) > Link to v2: Looks good to me now. Arnd
On Fri, 21 Jun 2024, Peter Griffin wrote: > Hi Lee, Arnd, Krzysztof, all, > > This series adds support to syscon driver for a new of_syscon_register_regmap() > api. > > Platforms such as gs101 require a special regmap to access PMU registers, which > in the existing upstream client drivers are accessed via syscon regmap. This > issue was partly solved in [1] whereby a custom regmap is created in exynos-pmu > and a new API exynos_get_pmu_regmap_by_phandle() created. > > One issue with the approach in [1] is that it required client drivers to be > updated from syscon_regmap_lookup_by_phandle() to > exynos_get_pmu_regmap_by_phandle() when obtaining the regmap. > > Whilst updating to exynos_get_pmu_regmap_by_phandle() was OK for exynos > specific drivers, it meant other drivers like syscon-reboot and syscon-poweroff > which span multiple SoC architectures could not be easily re-used. > > In previous review feedback for USB phy and gs101 poweroff driver Krzysztof > requested [2] that we take a more generic approach that other SoCs can also > leverage. > > The new of_syscon_register_regmap() api overcomes this limitation by allowing > a SoC driver like exynos-pmu to register it's SoC specific regmap with the > syscon driver. This keeps the SoC complexity out of syscon driver, and allows > client drivers to continue using syscon_regmap_lookup_by_phandle() as before. > The solution allows more code re-use and can be used by other SoC archs. > > Notes on probe ordering > > exynos-pmu runs at postcore_initcall, so all but one of the client drivers > (ufs phy, usb phy, watchdog) run after the regmap is created and registered. > > The one exception to this is pinctrl-samsung driver which is also > postcore_initcall level. The exynos_get_pmu_regmap() and > exynos_get_pmu_regmap_by_phandle() have been temporarily left to support > -EPROBE_DEFER for pinctrl-samsung driver. > > The longer term plan to solve that probe ordering issue is to enable > fw_devlink for syscon dt properties so they are correctly listed as > suppliers in /sys/class/devlink. I tested a PoC patch (see below) for > fw_devlink and that seemed to work fine. Once fw_devlink supports syscon I > believe exynos_get_pmu_regmap_by_phandle() api could be removed. The main issue > currently with fw_devlink syscon support is the wide diversity of dt property > naming currently in use. That was discussed previously here [3] > > 1248a1256,1257 > > DEFINE_SUFFIX_PROP(syscon_phandle, "syscon-phandle", NULL) > > DEFINE_SUFFIX_PROP(pmu_syscon, "pmu-syscon", NULL) > 1358a1368,1369 > > { .parse_prop = parse_syscon_phandle, }, > > { .parse_prop = parse_pmu_syscon, }, > > > Note one previous concern from Saravana about syscon potentially probing > before exynos-pmu driver and it relying on drivers/Makefile ordering. I tested > this and even if mfd is listed before soc in drivers/Makefile exynos-pmu > always probes first due to syscon driver not setting a .of_match_table entry. > > Once the syscon and exynos-pmu patchs are queued I will send patches for > watchdog and ufs phy drivers to switch back to syscon_regmap_lookup_by_phandle() > > Many thanks, > > Peter. > > [1] https://lore.kernel.org/linux-arm-kernel/20240219204238.356942-1-peter.griffin@linaro.org/T/ > [2] https://lore.kernel.org/lkml/06383015-51b2-4f4c-9fd8-e4f7ce12f44e@kernel.org/ > [3] https://lore.kernel.org/all/CAGETcx-CCpaV7R0O0HpDpoX6KxQBuJiMmKdWA8nDE-5Qj2Sa7g@mail.gmail.com/ > > Changes since v2: > - Move allocation outside spinlock area (Arnd) > Link to v2: > - https://lore.kernel.org/linux-arm-kernel/20240620112446.1286223-1-peter.griffin@linaro.org/ > > Changes since v1: > - Collect by tags > - Keep syscon lock held for check and adding entry (Krzysztof) > - pass pmu_np not np to syscon_node_to_regmap() (William) > > Link to v1: > - https://lore.kernel.org/linux-arm-kernel/20240614140421.3172674-1-peter.griffin@linaro.org/ > > Peter Griffin (2): > mfd: syscon: add of_syscon_register_regmap() API > soc: samsung: exynos-pmu: update to use of_syscon_register_regmap() > > drivers/mfd/syscon.c | 48 ++++++++++++++++++++++++++++++++ > drivers/soc/samsung/exynos-pmu.c | 38 ++++++++++--------------- > include/linux/mfd/syscon.h | 8 ++++++ > 3 files changed, 70 insertions(+), 24 deletions(-) Applied and submitted for build testing. If all is good, I'll send out a PR for the other maintainer(s). Note to self: ib-mfd-soc-samsung-6.11