4 files changed, 99 insertions, 8 deletions

diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index cf3fd549e16d..6b07b739f914 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -848,6 +848,9 @@ static inline unsigned int decode_config5(struct cpuinfo_mips *c)
 	if (config5 & MIPS_CONF5_CA2)
 		c->ases |= MIPS_ASE_MIPS16E2;
 
+	if (config5 & MIPS_CONF5_CRCP)
+		elf_hwcap |= HWCAP_MIPS_CRC32;
+
 	return config5 & MIPS_CONF_M;
 }
 
diff --git a/arch/mips/kernel/pm-cps.c b/arch/mips/kernel/pm-cps.c
index 421e06dfee72..55c3fbeb2df6 100644
--- a/arch/mips/kernel/pm-cps.c
+++ b/arch/mips/kernel/pm-cps.c
@@ -12,6 +12,7 @@
 #include <linux/init.h>
 #include <linux/percpu.h>
 #include <linux/slab.h>
+#include <linux/suspend.h>
 
 #include <asm/asm-offsets.h>
 #include <asm/cacheflush.h>
@@ -670,6 +671,34 @@ static int cps_pm_online_cpu(unsigned int cpu)
 	return 0;
 }
 
+static int cps_pm_power_notifier(struct notifier_block *this,
+				 unsigned long event, void *ptr)
+{
+	unsigned int stat;
+
+	switch (event) {
+	case PM_SUSPEND_PREPARE:
+		stat = read_cpc_cl_stat_conf();
+		/*
+		 * If we're attempting to suspend the system and power down all
+		 * of the cores, the JTAG detect bit indicates that the CPC will
+		 * instead put the cores into clock-off state. In this state
+		 * a connected debugger can cause the CPU to attempt
+		 * interactions with the powered down system. At best this will
+		 * fail. At worst, it can hang the NoC, requiring a hard reset.
+		 * To avoid this, just block system suspend if a JTAG probe
+		 * is detected.
+		 */
+		if (stat & CPC_Cx_STAT_CONF_EJTAG_PROBE) {
+			pr_warn("JTAG probe is connected - abort suspend\n");
+			return NOTIFY_BAD;
+		}
+		return NOTIFY_DONE;
+	default:
+		return NOTIFY_DONE;
+	}
+}
+
 static int __init cps_pm_init(void)
 {
 	/* A CM is required for all non-coherent states */
@@ -705,6 +734,8 @@ static int __init cps_pm_init(void)
 		pr_warn("pm-cps: no CPC, clock & power gating unavailable\n");
 	}
 
+	pm_notifier(cps_pm_power_notifier, 0);
+
 	return cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "mips/cps_pm:online",
 				 cps_pm_online_cpu, NULL);
 }
diff --git a/arch/mips/kernel/reset.c b/arch/mips/kernel/reset.c
index 7c746d3458e7..6288780b779e 100644
--- a/arch/mips/kernel/reset.c
+++ b/arch/mips/kernel/reset.c
@@ -13,6 +13,9 @@
 #include <linux/reboot.h>
 #include <linux/delay.h>
 
+#include <asm/compiler.h>
+#include <asm/idle.h>
+#include <asm/mipsregs.h>
 #include <asm/reboot.h>
 
 /*
@@ -26,6 +29,62 @@ void (*pm_power_off)(void);
 
 EXPORT_SYMBOL(pm_power_off);
 
+static void machine_hang(void)
+{
+	/*
+	 * We're hanging the system so we don't want to be interrupted anymore.
+	 * Any interrupt handlers that ran would at best be useless & at worst
+	 * go awry because the system isn't in a functional state.
+	 */
+	local_irq_disable();
+
+	/*
+	 * Mask all interrupts, giving us a better chance of remaining in the
+	 * low power wait state.
+	 */
+	clear_c0_status(ST0_IM);
+
+	while (true) {
+		if (cpu_has_mips_r) {
+			/*
+			 * We know that the wait instruction is supported so
+			 * make use of it directly, leaving interrupts
+			 * disabled.
+			 */
+			asm volatile(
+				".set	push\n\t"
+				".set	" MIPS_ISA_ARCH_LEVEL "\n\t"
+				"wait\n\t"
+				".set	pop");
+		} else if (cpu_wait) {
+			/*
+			 * Try the cpu_wait() callback. This isn't ideal since
+			 * it'll re-enable interrupts, but that ought to be
+			 * harmless given that they're all masked.
+			 */
+			cpu_wait();
+			local_irq_disable();
+		} else {
+			/*
+			 * We're going to burn some power running round the
+			 * loop, but we don't really have a choice. This isn't
+			 * a path we should expect to run for long during
+			 * typical use anyway.
+			 */
+		}
+
+		/*
+		 * In most modern MIPS CPUs interrupts will cause the wait
+		 * instruction to graduate even when disabled, and in some
+		 * cases even when masked. In order to prevent a timer
+		 * interrupt from continuously taking us out of the low power
+		 * wait state, we clear any pending timer interrupt here.
+		 */
+		if (cpu_has_counter)
+			write_c0_compare(0);
+	}
+}
+
 void machine_restart(char *command)
 {
 	if (_machine_restart)
@@ -38,8 +97,7 @@ void machine_restart(char *command)
 	do_kernel_restart(command);
 	mdelay(1000);
 	pr_emerg("Reboot failed -- System halted\n");
-	local_irq_disable();
-	while (1);
+	machine_hang();
 }
 
 void machine_halt(void)
@@ -51,8 +109,7 @@ void machine_halt(void)
 	preempt_disable();
 	smp_send_stop();
 #endif
-	local_irq_disable();
-	while (1);
+	machine_hang();
 }
 
 void machine_power_off(void)
@@ -64,6 +121,5 @@ void machine_power_off(void)
 	preempt_disable();
 	smp_send_stop();
 #endif
-	local_irq_disable();
-	while (1);
+	machine_hang();
 }
diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 5f8b0a9e30b3..563188ac6fa2 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -155,7 +155,8 @@ void __init detect_memory_region(phys_addr_t start, phys_addr_t sz_min, phys_add
 	add_memory_region(start, size, BOOT_MEM_RAM);
 }
 
-bool __init memory_region_available(phys_addr_t start, phys_addr_t size)
+static bool __init __maybe_unused memory_region_available(phys_addr_t start,
+							  phys_addr_t size)
 {
 	int i;
 	bool in_ram = false, free = true;
@@ -453,7 +454,7 @@ static void __init bootmem_init(void)
 		pr_info("Wasting %lu bytes for tracking %lu unused pages\n",
 			(min_low_pfn - ARCH_PFN_OFFSET) * sizeof(struct page),
 			min_low_pfn - ARCH_PFN_OFFSET);
-	} else if (min_low_pfn < ARCH_PFN_OFFSET) {
+	} else if (ARCH_PFN_OFFSET - min_low_pfn > 0UL) {
 		pr_info("%lu free pages won't be used\n",
 			ARCH_PFN_OFFSET - min_low_pfn);
 	}