lib: sbi_hsm: handle failure when hart_stop returns SBI_ENOTSUPP

Make use of generic warm-boot path when platform hart_stop callback
returns SBI_ENOTSUPP, in case certain hart can not turn off its
power domain, or it detects some error occured in power management
unit, it can fall through warm-boot flow and wait for interrupt in
sbi_hsm_hart_wait().

Also improves comment in sbi_hsm_hart_wait().

Signed-off-by: Yu Chien Peter Lin <peterlin@andestech.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>

diff --git a/include/sbi/sbi_hsm.h b/include/sbi/sbi_hsm.h
index c2a728a..1170127 100644 (file)
--- a/include/sbi/sbi_hsm.h
+++ b/include/sbi/sbi_hsm.h
@@ -21,8 +21,12 @@ struct sbi_hsm_device {
        int (*hart_start)(u32 hartid, ulong saddr);
 
        /**
-        * Stop (or power-down) the current hart from running. This call
-        * doesn't expect to return if success.
+        * Stop (or power-down) the current hart from running.
+        *
+        * Return SBI_ENOTSUPP if the hart does not support platform-specific
+        * stop actions.
+        *
+        * For successful stop, the call won't return.
         */
        int (*hart_stop)(void);
 

diff --git a/lib/sbi/sbi_hsm.c b/lib/sbi/sbi_hsm.c
index c0a5505..d4cce4a 100644 (file)
--- a/lib/sbi/sbi_hsm.c
+++ b/lib/sbi/sbi_hsm.c
@@ -116,7 +116,7 @@ static void sbi_hsm_hart_wait(struct sbi_scratch *scratch, u32 hartid)
        /* Set MSIE and MEIE bits to receive IPI */
        csr_set(CSR_MIE, MIP_MSIP | MIP_MEIP);
 
-       /* Wait for hart_add call*/
+       /* Wait for state transition requested by sbi_hsm_hart_start() */
        while (atomic_read(&hdata->state) != SBI_HSM_STATE_START_PENDING) {
                wfi();
        };
@@ -228,9 +228,8 @@ void __noreturn sbi_hsm_exit(struct sbi_scratch *scratch)
                goto fail_exit;
 
        if (hsm_device_has_hart_hotplug()) {
-               hsm_device_hart_stop();
-               /* It should never reach here */
-               goto fail_exit;
+               if (hsm_device_hart_stop() != SBI_ENOTSUPP)
+                       goto fail_exit;
        }
 
        /**