clocksource/drivers/riscv: Patch riscv_clock_next_event() jump before first use

A static key is used to select between SBI and Sstc timer usage in
riscv_clock_next_event(), but currently the direction is resolved
after cpuhp_setup_state() is called (which sets the next event).  The
first event will therefore fall through the sbi_set_timer() path; this
breaks Sstc-only systems.  So, apply the jump patching before first
use.

Fixes: 9f7a8ff6391f ("RISC-V: Prefer sstc extension if available")
Signed-off-by: Matt Evans <mev@rivosinc.com>
Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/CDDAB2D0-264E-42F3-8E31-BA210BEB8EC1@rivosinc.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c
index d8cb629d3aab26d562143dde4d4c23238c8eaad1..5f0f10c7e2226700ea56686a08e0f85e6a591fcc 100644 (file)
--- a/drivers/clocksource/timer-riscv.c
+++ b/drivers/clocksource/timer-riscv.c
@@ -192,6 +192,11 @@ static int __init riscv_timer_init_dt(struct device_node *n)
                return error;
        }
 
+       if (riscv_isa_extension_available(NULL, SSTC)) {
+               pr_info("Timer interrupt in S-mode is available via sstc extension\n");
+               static_branch_enable(&riscv_sstc_available);
+       }
+
        error = cpuhp_setup_state(CPUHP_AP_RISCV_TIMER_STARTING,
                         "clockevents/riscv/timer:starting",
                         riscv_timer_starting_cpu, riscv_timer_dying_cpu);
@@ -199,11 +204,6 @@ static int __init riscv_timer_init_dt(struct device_node *n)
                pr_err("cpu hp setup state failed for RISCV timer [%d]\n",
                       error);
 
-       if (riscv_isa_extension_available(NULL, SSTC)) {
-               pr_info("Timer interrupt in S-mode is available via sstc extension\n");
-               static_branch_enable(&riscv_sstc_available);
-       }
-
        return error;
 }