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. Peter [...]
