From: Douglas Anderson dianders@chromium.org
[ Upstream commit 44bd78dd2b8897f59b7e3963f088caadb7e4f047 ]
Some Chromebooks with Mediatek SoCs have a problem where the firmware doesn't properly save/restore certain GICR registers. Newer Chromebooks should fix this issue and we may be able to do firmware updates for old Chromebooks. At the moment, the only known issue with these Chromebooks is that we can't enable "pseudo NMIs" since the priority register can be lost. Enabling "pseudo NMIs" on Chromebooks with the problematic firmware causes crashes and freezes.
Let's detect devices with this problem and then disable "pseudo NMIs" on them. We'll detect the problem by looking for the presence of the "mediatek,broken-save-restore-fw" property in the GIC device tree node. Any devices with fixed firmware will not have this property.
Our detection plan works because we never bake a Chromebook's device tree into firmware. Instead, device trees are always bundled with the kernel. We'll update the device trees of all affected Chromebooks and then we'll never enable "pseudo NMI" on a kernel that is bundled with old device trees. When a firmware update is shipped that fixes this issue it will know to patch the device tree to remove the property.
In order to make this work, the quick detection mechanism of the GICv3 code is extended to be able to look for properties in addition to looking at "compatible".
Reviewed-by: Julius Werner jwerner@chromium.org Signed-off-by: Douglas Anderson dianders@chromium.org Signed-off-by: Marc Zyngier maz@kernel.org Link: https://lore.kernel.org/r/20230515131353.v2.2.I88dc0a0eb1d9d537de61604cd8994... Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/irqchip/irq-gic-common.c | 8 ++++++-- drivers/irqchip/irq-gic-common.h | 1 + drivers/irqchip/irq-gic-v3.c | 20 ++++++++++++++++++++ 3 files changed, 27 insertions(+), 2 deletions(-)
diff --git a/drivers/irqchip/irq-gic-common.c b/drivers/irqchip/irq-gic-common.c index a610821c8ff2a..de47b51cdadbe 100644 --- a/drivers/irqchip/irq-gic-common.c +++ b/drivers/irqchip/irq-gic-common.c @@ -16,7 +16,11 @@ void gic_enable_of_quirks(const struct device_node *np, const struct gic_quirk *quirks, void *data) { for (; quirks->desc; quirks++) { - if (!of_device_is_compatible(np, quirks->compatible)) + if (quirks->compatible && + !of_device_is_compatible(np, quirks->compatible)) + continue; + if (quirks->property && + !of_property_read_bool(np, quirks->property)) continue; if (quirks->init(data)) pr_info("GIC: enabling workaround for %s\n", @@ -28,7 +32,7 @@ void gic_enable_quirks(u32 iidr, const struct gic_quirk *quirks, void *data) { for (; quirks->desc; quirks++) { - if (quirks->compatible) + if (quirks->compatible || quirks->property) continue; if (quirks->iidr != (quirks->mask & iidr)) continue; diff --git a/drivers/irqchip/irq-gic-common.h b/drivers/irqchip/irq-gic-common.h index 27e3d4ed4f328..3db4592cda1c0 100644 --- a/drivers/irqchip/irq-gic-common.h +++ b/drivers/irqchip/irq-gic-common.h @@ -13,6 +13,7 @@ struct gic_quirk { const char *desc; const char *compatible; + const char *property; bool (*init)(void *data); u32 iidr; u32 mask; diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c index 6fcee221f2017..a605aa79435a4 100644 --- a/drivers/irqchip/irq-gic-v3.c +++ b/drivers/irqchip/irq-gic-v3.c @@ -39,6 +39,7 @@
#define FLAGS_WORKAROUND_GICR_WAKER_MSM8996 (1ULL << 0) #define FLAGS_WORKAROUND_CAVIUM_ERRATUM_38539 (1ULL << 1) +#define FLAGS_WORKAROUND_MTK_GICR_SAVE (1ULL << 2)
#define GIC_IRQ_TYPE_PARTITION (GIC_IRQ_TYPE_LPI + 1)
@@ -1720,6 +1721,15 @@ static bool gic_enable_quirk_msm8996(void *data) return true; }
+static bool gic_enable_quirk_mtk_gicr(void *data) +{ + struct gic_chip_data *d = data; + + d->flags |= FLAGS_WORKAROUND_MTK_GICR_SAVE; + + return true; +} + static bool gic_enable_quirk_cavium_38539(void *data) { struct gic_chip_data *d = data; @@ -1792,6 +1802,11 @@ static const struct gic_quirk gic_quirks[] = { .compatible = "qcom,msm8996-gic-v3", .init = gic_enable_quirk_msm8996, }, + { + .desc = "GICv3: Mediatek Chromebook GICR save problem", + .property = "mediatek,broken-save-restore-fw", + .init = gic_enable_quirk_mtk_gicr, + }, { .desc = "GICv3: HIP06 erratum 161010803", .iidr = 0x0204043b, @@ -1834,6 +1849,11 @@ static void gic_enable_nmi_support(void) if (!gic_prio_masking_enabled()) return;
+ if (gic_data.flags & FLAGS_WORKAROUND_MTK_GICR_SAVE) { + pr_warn("Skipping NMI enable due to firmware issues\n"); + return; + } + ppi_nmi_refs = kcalloc(gic_data.ppi_nr, sizeof(*ppi_nmi_refs), GFP_KERNEL); if (!ppi_nmi_refs) return;