| Message ID | 20240208161700.268570-1-peter.griffin@linaro.org |
|---|---|
| Headers | show |
| Series | Add regmap support to exynos-pmu for protected PMU regs | expand |
Hi Alexey, On Fri, 9 Feb 2024 at 14:52, Alexey Klimov <alexey.klimov@linaro.org> wrote: > > On Thu, 8 Feb 2024 at 16:21, Peter Griffin <peter.griffin@linaro.org> wrote: > > > > Some Exynos based SoCs like Tensor gs101 protect the PMU registers for > > security hardening reasons so that they are only write accessible in el3 > > via an SMC call. > > > > As most Exynos drivers that need to write PMU registers currently obtain a > > regmap via syscon (phys, pinctrl, watchdog). Support for the above usecase > > is implemented in this driver using a custom regmap similar to syscon to > > handle the SMC call. Platforms that don't secure PMU registers, get a mmio > > regmap like before. As regmaps abstract out the underlying register access > > changes to the leaf drivers are minimal. > > > > A new API exynos_get_pmu_regmap_by_phandle() is provided for leaf drivers > > that currently use syscon_regmap_lookup_by_phandle(). This also handles > > deferred probing. > > > > Signed-off-by: Peter Griffin <peter.griffin@linaro.org> > > Tested-by: Alexey Klimov <alexey.klimov@linaro.org> Thanks for testing this on odroid xu3 hardware! > > Apparently it seems tested-by should be provided for both patches. This was > also tested on odroid xu3 and I also have WIP code that depends on this > SMC-based regmap. No issues are observed and behaves as expected. > > > --- > > Changes since v3: > > - Fix PMUALIVE_MASK > > - Add TENSOR_ prefix > > - clear SET_BITS bits on each loop iteration > > - change set_bit to set_bits in func name > > - Fix some alignment > > - Add missing return on dev_err_probe > > - Reduce indentation in loop > > I no longer see the compilation warning related to struct device_node declared > inside parameter list with v4, I guess one line change addition in exynos-pmu.h > does the job. I added a forward declaration in the header to get rid of that compiler warning in v4, but it's not explicitly mentioned in the above changelog. Thanks, Peter. Peter
On Thu, Feb 8, 2024 at 10:21 AM Peter Griffin <peter.griffin@linaro.org> wrote: > > Some Exynos based SoCs like Tensor gs101 protect the PMU registers for > security hardening reasons so that they are only write accessible in el3 > via an SMC call. > > As most Exynos drivers that need to write PMU registers currently obtain a > regmap via syscon (phys, pinctrl, watchdog). Support for the above usecase > is implemented in this driver using a custom regmap similar to syscon to > handle the SMC call. Platforms that don't secure PMU registers, get a mmio > regmap like before. As regmaps abstract out the underlying register access > changes to the leaf drivers are minimal. > > A new API exynos_get_pmu_regmap_by_phandle() is provided for leaf drivers > that currently use syscon_regmap_lookup_by_phandle(). This also handles > deferred probing. > > Signed-off-by: Peter Griffin <peter.griffin@linaro.org> > --- > Changes since v3: > - Fix PMUALIVE_MASK > - Add TENSOR_ prefix > - clear SET_BITS bits on each loop iteration > - change set_bit to set_bits in func name > - Fix some alignment > - Add missing return on dev_err_probe > - Reduce indentation in loop > > Changes since v2 > - Add select REGMAP to Kconfig > - Add constant for SET/CLEAR bits > - Replace kerneldoc with one line comment > - Fix kerneldoc for EXPORT_SYMBOL_GPL funcs > - remove superfluous extern keyword > - dev_err_probe() on probe error > - shorten regmcfg name > - no compatibles inside probe, use match data > - don't mix declarations with/without initializations > - tensor_sec_reg_read() use mmio to avoid access restrictions > - Collect up Reviewed-by > - const for regmap_config structs > --- Tested-by: Sam Protsenko <semen.protsenko@linaro.org> Tested on my E850-96. All modules that use PMU are still functional with this patch (watchdog, USB host and Ethernet). No regressions. [snip]
Hi folks, This is a v4 of the series to add support for protected PMU registers found on gs101 and derivative SoCs. In v2 and later it was re-worked to be based on a regmap abstraction that I think leads to a much neater overall solution. The advantage of the regmap abstraction is that most leaf drivers that read/write PMU registers need minimal changes. Example of Exynos drivers that require PMU register access are: * watchdog * usb phy * mipi phy * ufs phy This series has been tested on Pixel 6 / gs101. If the various maintainers/ contributors of other Exynos SoCs like exynos850, exynosautov9, exynos5422 etc can test these patches on your respective systems that would be most appreciated. The expectation is this series would be merged via Krzysztofs Samsung Exynos tree. regards, Peter Changes since v3: - Fix PMUALIVE_MASK - Add TENSOR_ prefix - clear SET_BITS bits on each loop iteration - change set_bit to set_bits func name - Fix some alignment - Add missing return on dev_err_probe - Reduce indentation in loop Changes since v2 - Add select REGMAP to Kconfig - Add constant for SET/CLEAR bits - Replace kerneldoc with one line comment - Fix kerneldoc for EXPORT_SYMBOL_GPL funcs - remove superfluous extern keyword - dev_err_probe() on probe error - shorten regmcfg name - no compatibles inside probe, use match data - don't mix declarations with/without initializations - tensor_sec_reg_read() use mmio to avoid access restrictions - Collect up Reviewed-by - const for regmap_config structs Changes since v1: - Refactor to use custom regmap to abstract SMC register access (Sam / Guenter) - Add deferred probing support (Saravana / Krzysztof) v3 lore: https://lore.kernel.org/linux-arm-kernel/20240202145731.4082033-1-peter.griffin@linaro.org/ v2 lore: https://lore.kernel.org/lkml/20240129211912.3068411-1-peter.griffin@linaro.org/ v1 lore: https://lore.kernel.org/all/20240122225710.1952066-1-peter.griffin@linaro.org/ Peter Griffin (2): soc: samsung: exynos-pmu: Add regmap support for SoCs that protect PMU regs watchdog: s3c2410_wdt: use exynos_get_pmu_regmap_by_phandle() for PMU regs drivers/soc/samsung/Kconfig | 1 + drivers/soc/samsung/exynos-pmu.c | 235 ++++++++++++++++++++++++- drivers/soc/samsung/exynos-pmu.h | 1 + drivers/watchdog/Kconfig | 1 - drivers/watchdog/s3c2410_wdt.c | 8 +- include/linux/soc/samsung/exynos-pmu.h | 11 +- 6 files changed, 247 insertions(+), 10 deletions(-)