On 01/02/2024 13:51, Peter Griffin wrote: > Hi Krzysztof, > > On Tue, 30 Jan 2024 at 16:01, Krzysztof Kozlowski > <krzysztof.kozlowski@xxxxxxxxxx> wrote: >> >> On 29/01/2024 22:19, Peter Griffin wrote: >>> Some Exynos based SoCs like Tensor gs101 protect the PMU registers for >>> security hardening reasons so that they are only 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@xxxxxxxxxx> >>> --- >>> drivers/soc/samsung/exynos-pmu.c | 227 ++++++++++++++++++++++++- >>> include/linux/soc/samsung/exynos-pmu.h | 10 ++ >>> 2 files changed, 236 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/soc/samsung/exynos-pmu.c b/drivers/soc/samsung/exynos-pmu.c >>> index 250537d7cfd6..7bcc144e53a2 100644 >>> --- a/drivers/soc/samsung/exynos-pmu.c >>> +++ b/drivers/soc/samsung/exynos-pmu.c >>> @@ -5,6 +5,7 @@ >>> // >>> // Exynos - CPU PMU(Power Management Unit) support >>> >>> +#include <linux/arm-smccc.h> >>> #include <linux/of.h> >>> #include <linux/of_address.h> >>> #include <linux/mfd/core.h> >>> @@ -12,20 +13,159 @@ >>> #include <linux/of_platform.h> >>> #include <linux/platform_device.h> >>> #include <linux/delay.h> >>> +#include <linux/regmap.h> >>> >>> #include <linux/soc/samsung/exynos-regs-pmu.h> >>> #include <linux/soc/samsung/exynos-pmu.h> >>> >>> #include "exynos-pmu.h" >>> >>> +static struct platform_driver exynos_pmu_driver; >> >> I don't understand why do you need it. You can have only one >> pmu_context. The moment you probe second one, previous becomes invalid. >> >> I guess you want to parse phandle and check if just in case if it points >> to the right device, but still the original code is not ready for two >> PMU devices. I say either this problem should be solved entirely, >> allowing two devices, or just compare device node from phandle with >> device node of exynos_pmu_context->dev and return -EINVAL on mismatches. > > Apologies I didn't answer your original question. This wasn't about > having partial support for multiple pmu devices. It is being used by > driver_find_device_by_of_node() in exynos_get_pmu_regmap_by_phandle() > to determine that the exynos-pmu device has probed and therefore a > pmu_context exists and a regmap has been created and can be returned > to the caller (as opposed to doing a -EPROBE_DEFER). > > Is there some better/other API you recommend for this purpose? Just > checking pmu_context directly seems racy, so I don't think we should > do that. Hm, I don't quite get why you cannot use of_find_device_by_node()? Best regards, Krzysztof
