| Message ID | 20180301054820.42847-2-dbasehore@chromium.org (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Wed, Feb 28, 2018 at 09:48:18PM -0800, Derek Basehore wrote: > Some platforms power off GIC logic in suspend, so we need to > save/restore state. The distributor and redistributor registers need > to be handled in platform code due to access permissions on those > registers, but the ITS registers can be restored in the kernel. > > Signed-off-by: Derek Basehore <dbasehore@chromium.org> How much state do we have to save/restore? Given we can apparently read all this state, couldn't we *always* save the state, then upon resume detect if the state has been lost, restoring it if so? That way, we don't need a property in FW tables for DT or ACPI. [...] > @@ -3261,6 +3363,9 @@ static int __init its_probe_one(struct resource *res, > ctlr |= GITS_CTLR_ImDe; > writel_relaxed(ctlr, its->base + GITS_CTLR); > > + if (fwnode_property_present(handle, "reset-on-suspend")) > + its->flags |= ITS_FLAGS_SAVE_SUSPEND_STATE; Does this allow this property on an ACPI system? If we need this on ACPI, we need a spec update to handle this properly, and shouldn't use device properties like this. Thanks, Mark.
Hi Mark, On 01/03/18 11:41, Mark Rutland wrote: > On Wed, Feb 28, 2018 at 09:48:18PM -0800, Derek Basehore wrote: >> Some platforms power off GIC logic in suspend, so we need to >> save/restore state. The distributor and redistributor registers need >> to be handled in platform code due to access permissions on those >> registers, but the ITS registers can be restored in the kernel. >> >> Signed-off-by: Derek Basehore <dbasehore@chromium.org> > > How much state do we have to save/restore? > > Given we can apparently read all this state, couldn't we *always* save > the state, then upon resume detect if the state has been lost, restoring > it if so? > > That way, we don't need a property in FW tables for DT or ACPI. That's a good point. I guess that we could just compare the saved GITS_CTLR register and restore the full state only if the ITS comes back as disabled. I'm just a bit worried that it makes it an implicit convention between kernel an FW, which could change in funny ways. Importantly, the PSCI spec says states FW should restore *the whole state*. Obviously, it cannot to that on HW that doesn't allow you to read out the state, hence the DT flag that outlines the departure from the expected behaviour. I'm happy to go either way, but then I have the feeling that we should go back to quirking it on the actual implementation (GIC500 in this case) if we're to from the property. > > [...] > >> @@ -3261,6 +3363,9 @@ static int __init its_probe_one(struct resource *res, >> ctlr |= GITS_CTLR_ImDe; >> writel_relaxed(ctlr, its->base + GITS_CTLR); >> >> + if (fwnode_property_present(handle, "reset-on-suspend")) >> + its->flags |= ITS_FLAGS_SAVE_SUSPEND_STATE; > > Does this allow this property on an ACPI system? > > If we need this on ACPI, we need a spec update to handle this properly, > and shouldn't use device properties like this. Well spotted. I guess that dropping the property would fix that altogether, assuming we feel that the above is safe enough. Thoughts? M.
On Thu, Mar 1, 2018 at 4:29 AM, Marc Zyngier <marc.zyngier@arm.com> wrote: > Hi Mark, > > On 01/03/18 11:41, Mark Rutland wrote: >> On Wed, Feb 28, 2018 at 09:48:18PM -0800, Derek Basehore wrote: >>> Some platforms power off GIC logic in suspend, so we need to >>> save/restore state. The distributor and redistributor registers need >>> to be handled in platform code due to access permissions on those >>> registers, but the ITS registers can be restored in the kernel. >>> >>> Signed-off-by: Derek Basehore <dbasehore@chromium.org> >> >> How much state do we have to save/restore? >> >> Given we can apparently read all this state, couldn't we *always* save >> the state, then upon resume detect if the state has been lost, restoring >> it if so? >> >> That way, we don't need a property in FW tables for DT or ACPI. > > That's a good point. I guess that we could just compare the saved > GITS_CTLR register and restore the full state only if the ITS comes back > as disabled. > > I'm just a bit worried that it makes it an implicit convention between > kernel an FW, which could change in funny ways. Importantly, the PSCI > spec says states FW should restore *the whole state*. Obviously, it > cannot to that on HW that doesn't allow you to read out the state, hence > the DT flag that outlines the departure from the expected behaviour. > > I'm happy to go either way, but then I have the feeling that we should > go back to quirking it on the actual implementation (GIC500 in this > case) if we're to from the property. > >> >> [...] >> >>> @@ -3261,6 +3363,9 @@ static int __init its_probe_one(struct resource *res, >>> ctlr |= GITS_CTLR_ImDe; >>> writel_relaxed(ctlr, its->base + GITS_CTLR); >>> >>> + if (fwnode_property_present(handle, "reset-on-suspend")) >>> + its->flags |= ITS_FLAGS_SAVE_SUSPEND_STATE; >> >> Does this allow this property on an ACPI system? >> >> If we need this on ACPI, we need a spec update to handle this properly, >> and shouldn't use device properties like this. > > Well spotted. I guess that dropping the property would fix that > altogether, assuming we feel that the above is safe enough. > > Thoughts? I'm fine changing it to get rid of the devicetree property. What's the reason for quirking the behavior though? It's not that much code + data and nothing else relies on the state of the ITS getting disabled across suspend/resume. Even if something did, we'd have to resolve it with this feature anyways. > > M. > -- > Jazz is not dead. It just smells funny...
On 02/03/18 02:08, dbasehore . wrote: > On Thu, Mar 1, 2018 at 4:29 AM, Marc Zyngier <marc.zyngier@arm.com> wrote: >> Hi Mark, >> >> On 01/03/18 11:41, Mark Rutland wrote: >>> On Wed, Feb 28, 2018 at 09:48:18PM -0800, Derek Basehore wrote: >>>> Some platforms power off GIC logic in suspend, so we need to >>>> save/restore state. The distributor and redistributor registers need >>>> to be handled in platform code due to access permissions on those >>>> registers, but the ITS registers can be restored in the kernel. >>>> >>>> Signed-off-by: Derek Basehore <dbasehore@chromium.org> >>> >>> How much state do we have to save/restore? >>> >>> Given we can apparently read all this state, couldn't we *always* save >>> the state, then upon resume detect if the state has been lost, restoring >>> it if so? >>> >>> That way, we don't need a property in FW tables for DT or ACPI. >> >> That's a good point. I guess that we could just compare the saved >> GITS_CTLR register and restore the full state only if the ITS comes back >> as disabled. >> >> I'm just a bit worried that it makes it an implicit convention between >> kernel an FW, which could change in funny ways. Importantly, the PSCI >> spec says states FW should restore *the whole state*. Obviously, it >> cannot to that on HW that doesn't allow you to read out the state, hence >> the DT flag that outlines the departure from the expected behaviour. >> >> I'm happy to go either way, but then I have the feeling that we should >> go back to quirking it on the actual implementation (GIC500 in this >> case) if we're to from the property. >> >>> >>> [...] >>> >>>> @@ -3261,6 +3363,9 @@ static int __init its_probe_one(struct resource *res, >>>> ctlr |= GITS_CTLR_ImDe; >>>> writel_relaxed(ctlr, its->base + GITS_CTLR); >>>> >>>> + if (fwnode_property_present(handle, "reset-on-suspend")) >>>> + its->flags |= ITS_FLAGS_SAVE_SUSPEND_STATE; >>> >>> Does this allow this property on an ACPI system? >>> >>> If we need this on ACPI, we need a spec update to handle this properly, >>> and shouldn't use device properties like this. >> >> Well spotted. I guess that dropping the property would fix that >> altogether, assuming we feel that the above is safe enough. >> >> Thoughts? > > I'm fine changing it to get rid of the devicetree property. > > What's the reason for quirking the behavior though? It's not that much > code + data and nothing else relies on the state of the ITS getting > disabled across suspend/resume. Even if something did, we'd have to > resolve it with this feature anyways. The reason we do this is to cope with GIC500 having the collection state in registers instead of memory. If we didn't have this extraordinary misfeature, FW could do a full save/restore of the ITS, and we wouldn't have to do anything (which is what the driver currently expects). A middle ground approach is to limit the feature to systems where GITS_TYPER.HCC is non-zero instead of limiting it to GIC500. Pretty easy to fix. This should have the same effect, as GIC500 is the only implementation I'm aware of with HCC!=0. Given that we're already at -rc5 and that I'd like to queue things for 4.17, I've made this change myself and queued patches 1 and 3 here[1]. Can you please have a look at let me know if that works for you? Thanks, M. [1] git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git irq/irqchip-next
On Wed, Mar 14, 2018 at 3:22 AM, Marc Zyngier <marc.zyngier@arm.com> wrote: > On 02/03/18 02:08, dbasehore . wrote: >> On Thu, Mar 1, 2018 at 4:29 AM, Marc Zyngier <marc.zyngier@arm.com> wrote: >>> Hi Mark, >>> >>> On 01/03/18 11:41, Mark Rutland wrote: >>>> On Wed, Feb 28, 2018 at 09:48:18PM -0800, Derek Basehore wrote: >>>>> Some platforms power off GIC logic in suspend, so we need to >>>>> save/restore state. The distributor and redistributor registers need >>>>> to be handled in platform code due to access permissions on those >>>>> registers, but the ITS registers can be restored in the kernel. >>>>> >>>>> Signed-off-by: Derek Basehore <dbasehore@chromium.org> >>>> >>>> How much state do we have to save/restore? >>>> >>>> Given we can apparently read all this state, couldn't we *always* save >>>> the state, then upon resume detect if the state has been lost, restoring >>>> it if so? >>>> >>>> That way, we don't need a property in FW tables for DT or ACPI. >>> >>> That's a good point. I guess that we could just compare the saved >>> GITS_CTLR register and restore the full state only if the ITS comes back >>> as disabled. >>> >>> I'm just a bit worried that it makes it an implicit convention between >>> kernel an FW, which could change in funny ways. Importantly, the PSCI >>> spec says states FW should restore *the whole state*. Obviously, it >>> cannot to that on HW that doesn't allow you to read out the state, hence >>> the DT flag that outlines the departure from the expected behaviour. >>> >>> I'm happy to go either way, but then I have the feeling that we should >>> go back to quirking it on the actual implementation (GIC500 in this >>> case) if we're to from the property. >>> >>>> >>>> [...] >>>> >>>>> @@ -3261,6 +3363,9 @@ static int __init its_probe_one(struct resource *res, >>>>> ctlr |= GITS_CTLR_ImDe; >>>>> writel_relaxed(ctlr, its->base + GITS_CTLR); >>>>> >>>>> + if (fwnode_property_present(handle, "reset-on-suspend")) >>>>> + its->flags |= ITS_FLAGS_SAVE_SUSPEND_STATE; >>>> >>>> Does this allow this property on an ACPI system? >>>> >>>> If we need this on ACPI, we need a spec update to handle this properly, >>>> and shouldn't use device properties like this. >>> >>> Well spotted. I guess that dropping the property would fix that >>> altogether, assuming we feel that the above is safe enough. >>> >>> Thoughts? >> >> I'm fine changing it to get rid of the devicetree property. >> >> What's the reason for quirking the behavior though? It's not that much >> code + data and nothing else relies on the state of the ITS getting >> disabled across suspend/resume. Even if something did, we'd have to >> resolve it with this feature anyways. > > The reason we do this is to cope with GIC500 having the collection state > in registers instead of memory. If we didn't have this extraordinary > misfeature, FW could do a full save/restore of the ITS, and we wouldn't > have to do anything (which is what the driver currently expects). > > A middle ground approach is to limit the feature to systems where > GITS_TYPER.HCC is non-zero instead of limiting it to GIC500. Pretty easy > to fix. This should have the same effect, as GIC500 is the only > implementation I'm aware of with HCC!=0. > > Given that we're already at -rc5 and that I'd like to queue things for > 4.17, I've made this change myself and queued patches 1 and 3 here[1]. > > Can you please have a look at let me know if that works for you? > Assuming that your fine with only having the GIC500 implementations that have HCC as non-zero getting ITS registers restored in the kernel. As far as I can tell, this can happen in firmware for all implementations. It's only the code to resend that MAPC on resume that needs to be in the kernel. > Thanks, > > M. > > [1] git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git > irq/irqchip-next > -- > Jazz is not dead. It just smells funny...
On Wed, Mar 14, 2018 at 2:44 PM, dbasehore . <dbasehore@chromium.org> wrote: > On Wed, Mar 14, 2018 at 3:22 AM, Marc Zyngier <marc.zyngier@arm.com> wrote: >> On 02/03/18 02:08, dbasehore . wrote: >>> On Thu, Mar 1, 2018 at 4:29 AM, Marc Zyngier <marc.zyngier@arm.com> wrote: >>>> Hi Mark, >>>> >>>> On 01/03/18 11:41, Mark Rutland wrote: >>>>> On Wed, Feb 28, 2018 at 09:48:18PM -0800, Derek Basehore wrote: >>>>>> Some platforms power off GIC logic in suspend, so we need to >>>>>> save/restore state. The distributor and redistributor registers need >>>>>> to be handled in platform code due to access permissions on those >>>>>> registers, but the ITS registers can be restored in the kernel. >>>>>> >>>>>> Signed-off-by: Derek Basehore <dbasehore@chromium.org> >>>>> >>>>> How much state do we have to save/restore? >>>>> >>>>> Given we can apparently read all this state, couldn't we *always* save >>>>> the state, then upon resume detect if the state has been lost, restoring >>>>> it if so? >>>>> >>>>> That way, we don't need a property in FW tables for DT or ACPI. >>>> >>>> That's a good point. I guess that we could just compare the saved >>>> GITS_CTLR register and restore the full state only if the ITS comes back >>>> as disabled. >>>> >>>> I'm just a bit worried that it makes it an implicit convention between >>>> kernel an FW, which could change in funny ways. Importantly, the PSCI >>>> spec says states FW should restore *the whole state*. Obviously, it >>>> cannot to that on HW that doesn't allow you to read out the state, hence >>>> the DT flag that outlines the departure from the expected behaviour. >>>> >>>> I'm happy to go either way, but then I have the feeling that we should >>>> go back to quirking it on the actual implementation (GIC500 in this >>>> case) if we're to from the property. >>>> >>>>> >>>>> [...] >>>>> >>>>>> @@ -3261,6 +3363,9 @@ static int __init its_probe_one(struct resource *res, >>>>>> ctlr |= GITS_CTLR_ImDe; >>>>>> writel_relaxed(ctlr, its->base + GITS_CTLR); >>>>>> >>>>>> + if (fwnode_property_present(handle, "reset-on-suspend")) >>>>>> + its->flags |= ITS_FLAGS_SAVE_SUSPEND_STATE; >>>>> >>>>> Does this allow this property on an ACPI system? >>>>> >>>>> If we need this on ACPI, we need a spec update to handle this properly, >>>>> and shouldn't use device properties like this. >>>> >>>> Well spotted. I guess that dropping the property would fix that >>>> altogether, assuming we feel that the above is safe enough. >>>> >>>> Thoughts? >>> >>> I'm fine changing it to get rid of the devicetree property. >>> >>> What's the reason for quirking the behavior though? It's not that much >>> code + data and nothing else relies on the state of the ITS getting >>> disabled across suspend/resume. Even if something did, we'd have to >>> resolve it with this feature anyways. >> >> The reason we do this is to cope with GIC500 having the collection state >> in registers instead of memory. If we didn't have this extraordinary >> misfeature, FW could do a full save/restore of the ITS, and we wouldn't >> have to do anything (which is what the driver currently expects). >> >> A middle ground approach is to limit the feature to systems where >> GITS_TYPER.HCC is non-zero instead of limiting it to GIC500. Pretty easy >> to fix. This should have the same effect, as GIC500 is the only >> implementation I'm aware of with HCC!=0. >> >> Given that we're already at -rc5 and that I'd like to queue things for >> 4.17, I've made this change myself and queued patches 1 and 3 here[1]. >> >> Can you please have a look at let me know if that works for you? >> > > Assuming that your fine with only having the GIC500 implementations > that have HCC as non-zero getting ITS registers restored in the > kernel. As far as I can tell, this can happen in firmware for all > implementations. It's only the code to resend that MAPC on resume that > needs to be in the kernel. Actually, I guess we can't tell if we need to resend MAPC on resume if the firmware restores the state. Assuming it's a problem to just resend MAPC all the time, only restoring the ITS registers in the kernel when HCC != 0 makes sense. > >> Thanks, >> >> M. >> >> [1] git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git >> irq/irqchip-next >> -- >> Jazz is not dead. It just smells funny...
On 14/03/18 21:44, dbasehore . wrote: > On Wed, Mar 14, 2018 at 3:22 AM, Marc Zyngier <marc.zyngier@arm.com> wrote: >> On 02/03/18 02:08, dbasehore . wrote: >>> On Thu, Mar 1, 2018 at 4:29 AM, Marc Zyngier <marc.zyngier@arm.com> wrote: >>>> Hi Mark, >>>> >>>> On 01/03/18 11:41, Mark Rutland wrote: >>>>> On Wed, Feb 28, 2018 at 09:48:18PM -0800, Derek Basehore wrote: >>>>>> Some platforms power off GIC logic in suspend, so we need to >>>>>> save/restore state. The distributor and redistributor registers need >>>>>> to be handled in platform code due to access permissions on those >>>>>> registers, but the ITS registers can be restored in the kernel. >>>>>> >>>>>> Signed-off-by: Derek Basehore <dbasehore@chromium.org> >>>>> >>>>> How much state do we have to save/restore? >>>>> >>>>> Given we can apparently read all this state, couldn't we *always* save >>>>> the state, then upon resume detect if the state has been lost, restoring >>>>> it if so? >>>>> >>>>> That way, we don't need a property in FW tables for DT or ACPI. >>>> >>>> That's a good point. I guess that we could just compare the saved >>>> GITS_CTLR register and restore the full state only if the ITS comes back >>>> as disabled. >>>> >>>> I'm just a bit worried that it makes it an implicit convention between >>>> kernel an FW, which could change in funny ways. Importantly, the PSCI >>>> spec says states FW should restore *the whole state*. Obviously, it >>>> cannot to that on HW that doesn't allow you to read out the state, hence >>>> the DT flag that outlines the departure from the expected behaviour. >>>> >>>> I'm happy to go either way, but then I have the feeling that we should >>>> go back to quirking it on the actual implementation (GIC500 in this >>>> case) if we're to from the property. >>>> >>>>> >>>>> [...] >>>>> >>>>>> @@ -3261,6 +3363,9 @@ static int __init its_probe_one(struct resource *res, >>>>>> ctlr |= GITS_CTLR_ImDe; >>>>>> writel_relaxed(ctlr, its->base + GITS_CTLR); >>>>>> >>>>>> + if (fwnode_property_present(handle, "reset-on-suspend")) >>>>>> + its->flags |= ITS_FLAGS_SAVE_SUSPEND_STATE; >>>>> >>>>> Does this allow this property on an ACPI system? >>>>> >>>>> If we need this on ACPI, we need a spec update to handle this properly, >>>>> and shouldn't use device properties like this. >>>> >>>> Well spotted. I guess that dropping the property would fix that >>>> altogether, assuming we feel that the above is safe enough. >>>> >>>> Thoughts? >>> >>> I'm fine changing it to get rid of the devicetree property. >>> >>> What's the reason for quirking the behavior though? It's not that much >>> code + data and nothing else relies on the state of the ITS getting >>> disabled across suspend/resume. Even if something did, we'd have to >>> resolve it with this feature anyways. >> >> The reason we do this is to cope with GIC500 having the collection state >> in registers instead of memory. If we didn't have this extraordinary >> misfeature, FW could do a full save/restore of the ITS, and we wouldn't >> have to do anything (which is what the driver currently expects). >> >> A middle ground approach is to limit the feature to systems where >> GITS_TYPER.HCC is non-zero instead of limiting it to GIC500. Pretty easy >> to fix. This should have the same effect, as GIC500 is the only >> implementation I'm aware of with HCC!=0. >> >> Given that we're already at -rc5 and that I'd like to queue things for >> 4.17, I've made this change myself and queued patches 1 and 3 here[1]. >> >> Can you please have a look at let me know if that works for you? >> > > Assuming that your fine with only having the GIC500 implementations > that have HCC as non-zero getting ITS registers restored in the > kernel. As far as I can tell, this can happen in firmware for all > implementations. It's only the code to resend that MAPC on resume that > needs to be in the kernel. We really do not want to be in the business of doing partial save/restore, with "à la carte" implementations. That be unmaintainable. If a FW implementation doesn't fully save/restore the ITS when HCC==0, then it is buggy, and it should be fixed. Thanks, M.
diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c index 1d3056f53747..926f76944a75 100644 --- a/drivers/irqchip/irq-gic-v3-its.c +++ b/drivers/irqchip/irq-gic-v3-its.c @@ -33,6 +33,7 @@ #include <linux/of_platform.h> #include <linux/percpu.h> #include <linux/slab.h> +#include <linux/syscore_ops.h> #include <linux/irqchip.h> #include <linux/irqchip/arm-gic-v3.h> @@ -46,6 +47,7 @@ #define ITS_FLAGS_CMDQ_NEEDS_FLUSHING (1ULL << 0) #define ITS_FLAGS_WORKAROUND_CAVIUM_22375 (1ULL << 1) #define ITS_FLAGS_WORKAROUND_CAVIUM_23144 (1ULL << 2) +#define ITS_FLAGS_SAVE_SUSPEND_STATE (1ULL << 3) #define RDIST_FLAGS_PROPBASE_NEEDS_FLUSHING (1 << 0) @@ -101,6 +103,8 @@ struct its_node { struct its_collection *collections; struct fwnode_handle *fwnode_handle; u64 (*get_msi_base)(struct its_device *its_dev); + u64 cbaser_save; + u32 ctlr_save; struct list_head its_device_list; u64 flags; unsigned long list_nr; @@ -3042,6 +3046,104 @@ static void its_enable_quirks(struct its_node *its) gic_enable_quirks(iidr, its_quirks, its); } +static int its_save_disable(void) +{ + struct its_node *its; + int err = 0; + + spin_lock(&its_lock); + list_for_each_entry(its, &its_nodes, entry) { + void __iomem *base; + + if (!(its->flags & ITS_FLAGS_SAVE_SUSPEND_STATE)) + continue; + + base = its->base; + its->ctlr_save = readl_relaxed(base + GITS_CTLR); + err = its_force_quiescent(base); + if (err) { + pr_err("ITS@%pa: failed to quiesce: %d\n", + &its->phys_base, err); + writel_relaxed(its->ctlr_save, base + GITS_CTLR); + goto err; + } + + its->cbaser_save = gits_read_cbaser(base + GITS_CBASER); + } + +err: + if (err) { + list_for_each_entry_continue_reverse(its, &its_nodes, entry) { + void __iomem *base; + + if (!(its->flags & ITS_FLAGS_SAVE_SUSPEND_STATE)) + continue; + + base = its->base; + writel_relaxed(its->ctlr_save, base + GITS_CTLR); + } + } + spin_unlock(&its_lock); + + return err; +} + +static void its_restore_enable(void) +{ + struct its_node *its; + int ret; + + spin_lock(&its_lock); + list_for_each_entry(its, &its_nodes, entry) { + void __iomem *base; + int i; + + if (!(its->flags & ITS_FLAGS_SAVE_SUSPEND_STATE)) + continue; + + base = its->base; + + /* + * Make sure that the ITS is disabled. If it fails to quiesce, + * don't restore it since writing to CBASER or BASER<n> + * registers is undefined according to the GIC v3 ITS + * Specification. + */ + ret = its_force_quiescent(base); + if (ret) { + pr_err("ITS@%pa: failed to quiesce on resume: %d\n", + &its->phys_base, ret); + continue; + } + + gits_write_cbaser(its->cbaser_save, base + GITS_CBASER); + + /* + * Writing CBASER resets CREADR to 0, so make CWRITER and + * cmd_write line up with it. + */ + its->cmd_write = its->cmd_base; + gits_write_cwriter(0, base + GITS_CWRITER); + + /* Restore GITS_BASER from the value cache. */ + for (i = 0; i < GITS_BASER_NR_REGS; i++) { + struct its_baser *baser = &its->tables[i]; + + if (!(baser->val & GITS_BASER_VALID)) + continue; + + its_write_baser(its, baser, baser->val); + } + writel_relaxed(its->ctlr_save, base + GITS_CTLR); + } + spin_unlock(&its_lock); +} + +static struct syscore_ops its_syscore_ops = { + .suspend = its_save_disable, + .resume = its_restore_enable, +}; + static int its_init_domain(struct fwnode_handle *handle, struct its_node *its) { struct irq_domain *inner_domain; @@ -3261,6 +3363,9 @@ static int __init its_probe_one(struct resource *res, ctlr |= GITS_CTLR_ImDe; writel_relaxed(ctlr, its->base + GITS_CTLR); + if (fwnode_property_present(handle, "reset-on-suspend")) + its->flags |= ITS_FLAGS_SAVE_SUSPEND_STATE; + err = its_init_domain(handle, its); if (err) goto out_free_tables; @@ -3517,5 +3622,7 @@ int __init its_init(struct fwnode_handle *handle, struct rdists *rdists, } } + register_syscore_ops(&its_syscore_ops); + return 0; }
Some platforms power off GIC logic in suspend, so we need to save/restore state. The distributor and redistributor registers need to be handled in platform code due to access permissions on those registers, but the ITS registers can be restored in the kernel. Signed-off-by: Derek Basehore <dbasehore@chromium.org> --- drivers/irqchip/irq-gic-v3-its.c | 107 +++++++++++++++++++++++++++++++ 1 file changed, 107 insertions(+)