irqchip/mips-gic: Allow forced affinity

Devices of the Realtek MIPS Otto platform use the official rtl-otto-timer
as clock event generator and CPU clocksource. It is registered for each CPU
startup via cpuhp_setup_state() and forces the affinity of the clockevent
interrupts to the appropriate CPU via irq_force_affinity().

On the "smaller" devices with a vendor specific interrupt controller
(supported by irq-realtek-rtl) the registration works fine. The "larger"
RTL931x series is based on a MIPS interAptiv dual core with a MIPS GIC
controller. Interrupt routing setup is cancelled because gic_set_affinity()
does not accept the current (not yet online) CPU as a target.

Relax the checks by evaluating the force parameter that is provided for
exactly this purpose like in other drivers. With this the affinity can be
set as follows:

 - force = false: allow to set affinity to any online cpu
 - force = true:  allow to set affinity to any cpu

Co-developed-by: Sebastian Gottschall <s.gottschall@dd-wrt.com>
Signed-off-by: Sebastian Gottschall <s.gottschall@dd-wrt.com>
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250621054952.380374-1-markus.stockhausen@gmx.de

diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c
index 34e8d09c12a0b2a9936ef4d4fb0acd319d7570dd..19a57c5e2b2ea402180c98372402327df9f1a5d4 100644 (file)
--- a/drivers/irqchip/irq-mips-gic.c
+++ b/drivers/irqchip/irq-mips-gic.c
@@ -375,9 +375,13 @@ static int gic_set_affinity(struct irq_data *d, const struct cpumask *cpumask,
        /*
         * The GIC specifies that we can only route an interrupt to one VP(E),
         * ie. CPU in Linux parlance, at a time. Therefore we always route to
-        * the first online CPU in the mask.
+        * the first forced or online CPU in the mask.
         */
-       cpu = cpumask_first_and(cpumask, cpu_online_mask);
+       if (force)
+               cpu = cpumask_first(cpumask);
+       else
+               cpu = cpumask_first_and(cpumask, cpu_online_mask);
+
        if (cpu >= NR_CPUS)
                return -EINVAL;