clocksource/drivers/arm_arch_timer_mmio: Add MMIO clocksource

The MMIO driver can also double as a clocksource, something that was
missing in its previous incarnation. Add it for completeness.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://lore.kernel.org/r/20250814154622.10193-5-maz@kernel.org

diff --git a/drivers/clocksource/arm_arch_timer_mmio.c b/drivers/clocksource/arm_arch_timer_mmio.c
index 3522d1d8cb97bd70b81d7ab9102a3114cf55f48c..ebe1987d651ebc40f472e255116b4f814bfae2db 100644 (file)
--- a/drivers/clocksource/arm_arch_timer_mmio.c
+++ b/drivers/clocksource/arm_arch_timer_mmio.c
@@ -45,6 +45,7 @@ enum arch_timer_access {
 
 struct arch_timer {
        struct clock_event_device       evt;
+       struct clocksource              cs;
        struct arch_timer_mem           *gt_block;
        void __iomem                    *base;
        enum arch_timer_access          access;
@@ -52,6 +53,7 @@ struct arch_timer {
 };
 
 #define evt_to_arch_timer(e) container_of(e, struct arch_timer, evt)
+#define cs_to_arch_timer(c) container_of(c, struct arch_timer, cs)
 
 static void arch_timer_mmio_write(struct arch_timer *timer,
                                  enum arch_timer_reg reg, u64 val)
@@ -128,6 +130,13 @@ static noinstr u64 arch_counter_mmio_get_cnt(struct arch_timer *t)
        return ((u64) cnt_hi << 32) | cnt_lo;
 }
 
+static u64 arch_mmio_counter_read(struct clocksource *cs)
+{
+       struct arch_timer *at = cs_to_arch_timer(cs);
+
+       return arch_counter_mmio_get_cnt(at);
+}
+
 static int arch_timer_mmio_shutdown(struct clock_event_device *clk)
 {
        struct arch_timer *at = evt_to_arch_timer(clk);
@@ -256,6 +265,16 @@ static void arch_timer_mmio_setup(struct arch_timer *at, int irq)
                                        (unsigned long)CLOCKSOURCE_MASK(56));
 
        enable_irq(at->evt.irq);
+
+       at->cs = (struct clocksource) {
+               .name   = "arch_mmio_counter",
+               .rating = 300,
+               .read   = arch_mmio_counter_read,
+               .mask   = CLOCKSOURCE_MASK(56),
+               .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
+       };
+
+       clocksource_register_hz(&at->cs, at->rate);
 }
 
 static int arch_timer_mmio_frame_register(struct platform_device *pdev,