MIPS: smp-cps: Add nothreads kernel parameter

When debugging a new system or core it can be useful to disable the use
of multithreading. Introduce a "nothreads" kernel command line parameter
that can be set in order to do so.

Signed-off-by: Paul Burton <[e-mail]>
Cc: Matt Redfearn <[e-mail]>
Cc: Rusty Russell <[e-mail]>
Cc: Niklas Cassel <[e-mail]>
Cc: Ezequiel Garcia <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Patchwork: https://patchwork.linux-mips.org/patch/12340/
Signed-off-by: Ralf Baechle <[e-mail]>

arch/mips/kernel/smp-cps.c

···
 #include <asm/time.h>
 #include <asm/uasm.h>
 
+static bool threads_disabled;
 static DECLARE_BITMAP(core_power, NR_CPUS);
 
 struct core_boot_config *mips_cps_core_bootcfg;
 
+static int __init setup_nothreads(char *s)
+{
+	threads_disabled = true;
+	return 0;
+}
+early_param("nothreads", setup_nothreads);
+
 static unsigned core_vpe_count(unsigned core)
 {
 	unsigned cfg;
+
+	if (threads_disabled)
+		return 1;
 
 	if ((!config_enabled(CONFIG_MIPS_MT_SMP) || !cpu_has_mipsmt)
 		&& (!config_enabled(CONFIG_CPU_MIPSR6) || !cpu_has_vp))