[PATCH] irqchip/gicv3: remove disabling redistributor and group1 non-secure interrupts

[Sudeep Holla]

As per the GICv3 specification, to power down a processor using GICv3
and allow automatic power-on if an interrupt must be sent to a processor,
software must set Enable to zero for all interrupt groups(by writing
to GICC_CTLR or ICC_IGRPEN{0,1}_EL1/3 as appropriate.

When commit 3708d52fc6bb ("irqchip: gic-v3: Implement CPU PM notifier")
was introduced there were no firmware implementations(in particular PSCI)
handling this.

Linux kernel may not be aware of the CPU power state details and might
fail to identify the power states that require quiescing the CPU
interface. Even if it can be aware of those details, it can't determine
which CPU power state have been triggered at the platform level and how
the power control is implemented.

This patch make disabling redistributor and group1 non-secure interrupts
in the power down path and re-enabling of redistributor in the power-up
path conditional. It will be handled in the kernel if and only if the
non-secure accesses are permitted to access and modify control registers.
It is left to the platform implementation otherwise.

Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
---
 drivers/irqchip/irq-gic-v3.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

Hi Christopher,

Can you check if ACPI processor idle works with this patch on QDF2432 ?
PSCI implementation much now deal with Grp1 interrupts when CPU is being
powered down during suspend/resume. I have pushed changes to ARM TF[1]

Regards,
Sudeep

[1] https://github.com/sudeep-holla/arm-trusted-firmware/commit/65d68ca64d12a4ce5b05a96808dd6f638451940d

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 6fc56c3466b0..a8db96540ca1 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -119,6 +119,12 @@ static void gic_redist_wait_for_rwp(void)
 	gic_do_wait_for_rwp(gic_data_rdist_rd_base());
 }

+/* Check whether it's single security state view */
+static bool gic_dist_security_disabled(void)
+{
+	return readl_relaxed(gic_data.dist_base + GICD_CTLR) & GICD_CTLR_DS;
+}
+
 #ifdef CONFIG_ARM64
 static DEFINE_STATIC_KEY_FALSE(is_cavium_thunderx);

@@ -671,9 +677,10 @@ static int gic_cpu_pm_notifier(struct notifier_block *self,
 			       unsigned long cmd, void *v)
 {
 	if (cmd == CPU_PM_EXIT) {
-		gic_enable_redist(true);
+		if (gic_dist_security_disabled())
+			gic_enable_redist(true);
 		gic_cpu_sys_reg_init();
-	} else if (cmd == CPU_PM_ENTER) {
+	} else if (cmd == CPU_PM_ENTER && gic_dist_security_disabled()) {
 		gic_write_grpen1(0);
 		gic_enable_redist(false);
 	}
--
2.7.4