| Message ID | 20240423-usb-phy-gs101-v1-2-ebdcb3ac174d@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | None | expand |
On 23/04/2024 19:06, André Draszik 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. > > The Exynos PMU driver handles this transparently when using > exynos_get_pmu_regmap_by_phandle(). > > Switch to using that API to support such SoCs. As this driver now no > longer depends on mfd syscon remove that header and Kconfig dependency. > > Signed-off-by: André Draszik <andre.draszik@linaro.org> > --- > drivers/phy/samsung/Kconfig | 1 - > drivers/phy/samsung/phy-exynos5-usbdrd.c | 4 ++-- > 2 files changed, 2 insertions(+), 3 deletions(-) > > diff --git a/drivers/phy/samsung/Kconfig b/drivers/phy/samsung/Kconfig > index f10afa3d7ff5..bb63fa710803 100644 > --- a/drivers/phy/samsung/Kconfig > +++ b/drivers/phy/samsung/Kconfig > @@ -82,7 +82,6 @@ config PHY_EXYNOS5_USBDRD > depends on HAS_IOMEM > depends on USB_DWC3_EXYNOS > select GENERIC_PHY > - select MFD_SYSCON > default y > help > Enable USB DRD PHY support for Exynos 5 SoC series. > diff --git a/drivers/phy/samsung/phy-exynos5-usbdrd.c b/drivers/phy/samsung/phy-exynos5-usbdrd.c > index 04171eed5b16..ac208b89f5a6 100644 > --- a/drivers/phy/samsung/phy-exynos5-usbdrd.c > +++ b/drivers/phy/samsung/phy-exynos5-usbdrd.c > @@ -18,9 +18,9 @@ > #include <linux/phy/phy.h> > #include <linux/platform_device.h> > #include <linux/mutex.h> > -#include <linux/mfd/syscon.h> > #include <linux/regmap.h> > #include <linux/regulator/consumer.h> > +#include <linux/soc/samsung/exynos-pmu.h> > #include <linux/soc/samsung/exynos-regs-pmu.h> This is getting out of hand: shall we expect to convert all the drivers from generic syscon to Exynos-specific API? What if one driver is some shared IP, like DWC USB3 controller? I already commented on Google hwrng driver: I prefer to keep the syscon API and change the syscon driver to expose proper regmap. IOW, use generic API syscon_regmap_lookup_by_phandle() and the type of regmap returned is defined by the provider (so node pointed by phandle). Best regards, Krzysztof
Hi Krzysztof, + Arnd & Lee (syscon maintainers) On Thu, 25 Apr 2024 at 08:47, Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> wrote: > > On 23/04/2024 19:06, André Draszik 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. > > > > The Exynos PMU driver handles this transparently when using > > exynos_get_pmu_regmap_by_phandle(). > > > > Switch to using that API to support such SoCs. As this driver now no > > longer depends on mfd syscon remove that header and Kconfig dependency. > > > > Signed-off-by: André Draszik <andre.draszik@linaro.org> > > --- > > drivers/phy/samsung/Kconfig | 1 - > > drivers/phy/samsung/phy-exynos5-usbdrd.c | 4 ++-- > > 2 files changed, 2 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/phy/samsung/Kconfig b/drivers/phy/samsung/Kconfig > > index f10afa3d7ff5..bb63fa710803 100644 > > --- a/drivers/phy/samsung/Kconfig > > +++ b/drivers/phy/samsung/Kconfig > > @@ -82,7 +82,6 @@ config PHY_EXYNOS5_USBDRD > > depends on HAS_IOMEM > > depends on USB_DWC3_EXYNOS > > select GENERIC_PHY > > - select MFD_SYSCON > > default y > > help > > Enable USB DRD PHY support for Exynos 5 SoC series. > > diff --git a/drivers/phy/samsung/phy-exynos5-usbdrd.c b/drivers/phy/samsung/phy-exynos5-usbdrd.c > > index 04171eed5b16..ac208b89f5a6 100644 > > --- a/drivers/phy/samsung/phy-exynos5-usbdrd.c > > +++ b/drivers/phy/samsung/phy-exynos5-usbdrd.c > > @@ -18,9 +18,9 @@ > > #include <linux/phy/phy.h> > > #include <linux/platform_device.h> > > #include <linux/mutex.h> > > -#include <linux/mfd/syscon.h> > > #include <linux/regmap.h> > > #include <linux/regulator/consumer.h> > > +#include <linux/soc/samsung/exynos-pmu.h> > > #include <linux/soc/samsung/exynos-regs-pmu.h> > > This is getting out of hand: shall we expect to convert all the drivers > from generic syscon to Exynos-specific API? I think certainly for the various exynos phy (usb, ufs, pcie, mipi) this change is required. I can do some more checking to see what other drivers are twiddling PMU bits downstream. > What if one driver is some > shared IP, like DWC USB3 controller? > > I already commented on Google hwrng driver: I think you mean syscon-poweroff but I get your point. The syscon-reboot / poweroff / reboot-mode drivers are examples of drivers where we may wish to use them, but today we can't as they are using syscon_regmap_lookup_by_phandle() API. > I prefer to keep the syscon > API and change the syscon driver to expose proper regmap. IOW, use > generic API syscon_regmap_lookup_by_phandle() and the type of regmap > returned is defined by the provider (so node pointed by phandle). > @Arnd - any more thoughts on Krzysztof idea above ^^ @Krzysztof - I did speak to Arnd about the idea you proposed (or my understanding of it at least), which was external drivers like exynos-pmu or altera-sysmgr.c could create the regmap and register it with syscon so it can be returned by syscon_regmap_lookup_by_phandle(). Arnd's initial feedback was he would prefer to keep the complexity out of syscon, and have the client driver support multiple backends (so syscon-reboot for example would support using either syscon_regmap_lookup_by_phandle() or exynos_get_pmu_regmap_by_phandle() to obtain it's regmap). There were also some concerns about syscon having to probe very early for some platforms. Thanks, Peter.
On 25/04/2024 12:02, Peter Griffin wrote: >> I prefer to keep the syscon >> API and change the syscon driver to expose proper regmap. IOW, use >> generic API syscon_regmap_lookup_by_phandle() and the type of regmap >> returned is defined by the provider (so node pointed by phandle). >> > > @Arnd - any more thoughts on Krzysztof idea above ^^ > > @Krzysztof - I did speak to Arnd about the idea you proposed (or my > understanding of it at least), which was external drivers like > exynos-pmu or altera-sysmgr.c could create the regmap and register it > with syscon so it can be returned by > syscon_regmap_lookup_by_phandle(). Arnd's initial feedback was he > would prefer to keep the complexity out of syscon, and have the client > driver support multiple backends (so syscon-reboot for example would > support using either syscon_regmap_lookup_by_phandle() or > exynos_get_pmu_regmap_by_phandle() to obtain it's regmap). There were > also some concerns about syscon having to probe very early for some > platforms. mfd/syscon.c is postcore_initcall, so it is not that very early, although earlier than drivers. However it does not support deferred probe and sometimes syscon providers might need clocks and resets. One syscon consumer (so regular driver like phy here) might work with different providers. E.g. on earlier arm and arm64 Exynos this was simple regmap. On Google GS this is SMC. On some foo-bar it might be call to hypervisor or something needing clocks. For me therefore the syscon consumer is like regmap consumer. You do not care who provides the regmap, just want i2c or mmio regmap. Of course the specific driver, so the consumer of regmap, knows the type of regmap it uses, so it requests i2c or mmio. Here we want to hide two different interfaces - mmio and SMC - behind one regmap. We solve it by using same regmap interface for consumer, but different syscon calls returning different regmaps. Anyway, I want to sort it out and have some sort of global policy, before we start doing such changes for Google GS. I am sure soon Qualcomm will come with their need for hypervisor quirks/regmaps etc. And then TI will come with some need. Best regards, Krzysztof
diff --git a/drivers/phy/samsung/Kconfig b/drivers/phy/samsung/Kconfig index f10afa3d7ff5..bb63fa710803 100644 --- a/drivers/phy/samsung/Kconfig +++ b/drivers/phy/samsung/Kconfig @@ -82,7 +82,6 @@ config PHY_EXYNOS5_USBDRD depends on HAS_IOMEM depends on USB_DWC3_EXYNOS select GENERIC_PHY - select MFD_SYSCON default y help Enable USB DRD PHY support for Exynos 5 SoC series. diff --git a/drivers/phy/samsung/phy-exynos5-usbdrd.c b/drivers/phy/samsung/phy-exynos5-usbdrd.c index 04171eed5b16..ac208b89f5a6 100644 --- a/drivers/phy/samsung/phy-exynos5-usbdrd.c +++ b/drivers/phy/samsung/phy-exynos5-usbdrd.c @@ -18,9 +18,9 @@ #include <linux/phy/phy.h> #include <linux/platform_device.h> #include <linux/mutex.h> -#include <linux/mfd/syscon.h> #include <linux/regmap.h> #include <linux/regulator/consumer.h> +#include <linux/soc/samsung/exynos-pmu.h> #include <linux/soc/samsung/exynos-regs-pmu.h> /* Exynos USB PHY registers */ @@ -1034,7 +1034,7 @@ static int exynos5_usbdrd_phy_probe(struct platform_device *pdev) return ret; } - reg_pmu = syscon_regmap_lookup_by_phandle(dev->of_node, + reg_pmu = exynos_get_pmu_regmap_by_phandle(dev->of_node, "samsung,pmu-syscon"); if (IS_ERR(reg_pmu)) { dev_err(dev, "Failed to lookup PMU regmap\n");
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. The Exynos PMU driver handles this transparently when using exynos_get_pmu_regmap_by_phandle(). Switch to using that API to support such SoCs. As this driver now no longer depends on mfd syscon remove that header and Kconfig dependency. Signed-off-by: André Draszik <andre.draszik@linaro.org> --- drivers/phy/samsung/Kconfig | 1 - drivers/phy/samsung/phy-exynos5-usbdrd.c | 4 ++-- 2 files changed, 2 insertions(+), 3 deletions(-)