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Date: Tue, 6 Feb 2018 16:40:32 +0000
From: Marc Zyngier <marc.zyngier@....com>
To: Derek Basehore <dbasehore@...omium.org>,
linux-kernel@...r.kernel.org
Cc: Soby.Mathew@....com, sudeep.holla@....com,
devicetree@...r.kernel.org, robh+dt@...nel.org,
mark.rutland@....com, linux-pm@...r.kernel.org,
rafael.j.wysocki@...el.com, tglx@...utronix.de,
briannorris@...omium.org
Subject: Re: [PATCH v4 4/5] irqchip/gic-v3-its: add ability to resend MAPC on
resume
On 03/02/18 01:24, Derek Basehore wrote:
> This adds functionality to resend the MAPC command to an ITS node on
> resume. If the ITS is powered down during suspend and the collections
> are not backed by memory, the ITS will lose that state. This just sets
> up the known state for the collections after the ITS is restored.
>
> This feature is enabled via Kconfig and a device tree entry.
>
> Signed-off-by: Derek Basehore <dbasehore@...omium.org>
> ---
> arch/arm64/Kconfig | 10 ++++
> drivers/irqchip/irq-gic-v3-its.c | 101 ++++++++++++++++++++++++---------------
> 2 files changed, 73 insertions(+), 38 deletions(-)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 53612879fe56..f38f1a7b4266 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -571,6 +571,16 @@ config HISILICON_ERRATUM_161600802
>
> If unsure, say Y.
>
> +config ARM_GIC500_COLLECTIONS_RESET
> + bool "GIC-500 Collections: Workaround for GIC-500 Collections on suspend reset"
> + default y
> + help
> + The GIC-500 can store Collections state internally for the ITS. If
> + the ITS is reset on suspend (ie from power getting disabled), the
> + collections need to be reconfigured on resume.
> +
> + If unsure, say Y.
> +
> config QCOM_FALKOR_ERRATUM_E1041
> bool "Falkor E1041: Speculative instruction fetches might cause errant memory access"
> default y
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index e13515cdb68f..63764efa4dcc 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -48,6 +48,7 @@
> #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 ITS_FLAGS_WORKAROUND_GIC500_MAPC (1ULL << 4)
>
> #define RDIST_FLAGS_PROPBASE_NEEDS_FLUSHING (1 << 0)
>
> @@ -1950,52 +1951,53 @@ static void its_cpu_init_lpis(void)
> dsb(sy);
> }
>
> -static void its_cpu_init_collection(void)
> +static void its_cpu_init_collection(struct its_node *its)
> {
> - struct its_node *its;
> - int cpu;
> -
> - spin_lock(&its_lock);
> - cpu = smp_processor_id();
> -
> - list_for_each_entry(its, &its_nodes, entry) {
> - u64 target;
> + int cpu = smp_processor_id();
> + u64 target;
>
> - /* avoid cross node collections and its mapping */
> - if (its->flags & ITS_FLAGS_WORKAROUND_CAVIUM_23144) {
> - struct device_node *cpu_node;
> + /* avoid cross node collections and its mapping */
> + if (its->flags & ITS_FLAGS_WORKAROUND_CAVIUM_23144) {
> + struct device_node *cpu_node;
>
> - cpu_node = of_get_cpu_node(cpu, NULL);
> - if (its->numa_node != NUMA_NO_NODE &&
> - its->numa_node != of_node_to_nid(cpu_node))
> - continue;
> - }
> + cpu_node = of_get_cpu_node(cpu, NULL);
> + if (its->numa_node != NUMA_NO_NODE &&
> + its->numa_node != of_node_to_nid(cpu_node))
> + return;
> + }
>
> + /*
> + * We now have to bind each collection to its target
> + * redistributor.
> + */
> + if (gic_read_typer(its->base + GITS_TYPER) & GITS_TYPER_PTA) {
> /*
> - * We now have to bind each collection to its target
> + * This ITS wants the physical address of the
> * redistributor.
> */
> - if (gic_read_typer(its->base + GITS_TYPER) & GITS_TYPER_PTA) {
> - /*
> - * This ITS wants the physical address of the
> - * redistributor.
> - */
> - target = gic_data_rdist()->phys_base;
> - } else {
> - /*
> - * This ITS wants a linear CPU number.
> - */
> - target = gic_read_typer(gic_data_rdist_rd_base() + GICR_TYPER);
> - target = GICR_TYPER_CPU_NUMBER(target) << 16;
> - }
> + target = gic_data_rdist()->phys_base;
> + } else {
> + /* This ITS wants a linear CPU number. */
> + target = gic_read_typer(gic_data_rdist_rd_base() + GICR_TYPER);
> + target = GICR_TYPER_CPU_NUMBER(target) << 16;
> + }
>
> - /* Perform collection mapping */
> - its->collections[cpu].target_address = target;
> - its->collections[cpu].col_id = cpu;
> + /* Perform collection mapping */
> + its->collections[cpu].target_address = target;
> + its->collections[cpu].col_id = cpu;
>
> - its_send_mapc(its, &its->collections[cpu], 1);
> - its_send_invall(its, &its->collections[cpu]);
> - }
> + its_send_mapc(its, &its->collections[cpu], 1);
> + its_send_invall(its, &its->collections[cpu]);
> +}
> +
> +static void its_cpu_init_collections(void)
> +{
> + struct its_node *its;
> +
> + spin_lock(&its_lock);
> +
> + list_for_each_entry(its, &its_nodes, entry)
> + its_cpu_init_collection(its);
>
> spin_unlock(&its_lock);
> }
> @@ -2997,6 +2999,18 @@ static bool __maybe_unused its_enable_quirk_hip07_161600802(void *data)
> return true;
> }
>
> +static bool __maybe_unused its_enable_quirk_gic500_collections(void *data)
> +{
> + struct its_node *its = data;
> +
> + if (fwnode_property_present(its->fwnode_handle,
> + "collections-reset-on-suspend")) {
> + its->flags |= ITS_FLAGS_WORKAROUND_GIC500_MAPC;
> + return true;
> + }
> + return false;
> +}
> +
> static const struct gic_quirk its_quirks[] = {
> #ifdef CONFIG_CAVIUM_ERRATUM_22375
> {
> @@ -3042,6 +3056,14 @@ static const struct gic_quirk its_quirks[] = {
> .mask = 0xffffffff,
> .init = its_enable_quirk_hip07_161600802,
> },
> +#endif
> +#ifdef CONFIG_ARM_GIC500_COLLECTIONS_RESET
> + {
> + .desc = "ITS: GIC-500 Collections Reset on Resume",
> + .iidr = 0x00000000,
> + .mask = 0xff000000,
> + .init = its_enable_quirk_gic500_collections,
> + },
> #endif
> {
> }
> @@ -3129,6 +3151,9 @@ static void its_restore_enable(void)
> }
> writel_relaxed(ctx->ctlr, base + GITS_CTLR);
> }
> +
> + if (its->flags & ITS_FLAGS_WORKAROUND_GIC500_MAPC)
> + its_cpu_init_collection(its);
> }
> spin_unlock(&its_lock);
> }
> @@ -3395,7 +3420,7 @@ int its_cpu_init(void)
> return -ENXIO;
> }
> its_cpu_init_lpis();
> - its_cpu_init_collection();
> + its_cpu_init_collections();
> }
>
> return 0;
>
I wonder if a better way to implement this is simply to bite the bullet
and implement the letter of the architecture:
If GITS_TYPER.HCC != 0, then collections 0...HCC-1 are held in HW, and
the rest in a SW-managed table. That would allow us to deal with this
without a quirk (which I asked for initially, apologies for changing my
mind).
We still the same DT flag to tell us we're going to be reset on suspend.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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