MIPS: CPS: Warn if a core doesn't start

When debugging core bringup it is useful to see the state of the CPC
sequencer, so output that value if the core hasn't started within a
reasonable amount of time (1 second). This avoids simply appearing to
the user to hang if a secondary core fails to start.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andrew Bresticker <abrestic@chromium.org>
Cc: linux-kernel@vger.kernel.org
Cc: Niklas Cassel <niklas.cassel@axis.com>
Cc: Ezequiel Garcia <ezequiel.garcia@imgtec.com>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/11205/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/kernel/smp-cps.c b/arch/mips/kernel/smp-cps.c
index 8b96750..48b1b75 100644 (file)
--- a/arch/mips/kernel/smp-cps.c
+++ b/arch/mips/kernel/smp-cps.c
@@ -8,6 +8,7 @@
  * option) any later version.
  */
 
+#include <linux/delay.h>
 #include <linux/io.h>
 #include <linux/irqchip/mips-gic.h>
 #include <linux/sched.h>
@@ -188,7 +189,8 @@ err_out:
 
 static void boot_core(unsigned core)
 {
-       u32 access;
+       u32 access, stat, seq_state;
+       unsigned timeout;
 
        /* Select the appropriate core */
        write_gcr_cl_other(core << CM_GCR_Cx_OTHER_CORENUM_SHF);
@@ -208,6 +210,28 @@ static void boot_core(unsigned core)
                /* Reset the core */
                mips_cpc_lock_other(core);
                write_cpc_co_cmd(CPC_Cx_CMD_RESET);
+
+               timeout = 100;
+               while (true) {
+                       stat = read_cpc_co_stat_conf();
+                       seq_state = stat & CPC_Cx_STAT_CONF_SEQSTATE_MSK;
+
+                       /* U6 == coherent execution, ie. the core is up */
+                       if (seq_state == CPC_Cx_STAT_CONF_SEQSTATE_U6)
+                               break;
+
+                       /* Delay a little while before we start warning */
+                       if (timeout) {
+                               timeout--;
+                               mdelay(10);
+                               continue;
+                       }
+
+                       pr_warn("Waiting for core %u to start... STAT_CONF=0x%x\n",
+                               core, stat);
+                       mdelay(1000);
+               }
+
                mips_cpc_unlock_other();
        } else {
                /* Take the core out of reset */