Merge tag 'mips_4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/jhogan/mips

Pull MIPS updates from James Hogan:
 "These are the main MIPS changes for 4.17. Rough overview:

   (1) generic platform: Add support for Microsemi Ocelot SoCs

   (2) crypto: Add CRC32 and CRC32C HW acceleration module

   (3) Various cleanups and misc improvements

  More detailed summary:

  Miscellaneous:
   - hang more efficiently on halt/powerdown/restart
   - pm-cps: Block system suspend when a JTAG probe is present
   - expand make help text for generic defconfigs
   - refactor handling of legacy defconfigs
   - determine the entry point from the ELF file header to fix microMIPS
     for certain toolchains
   - introduce isa-rev.h for MIPS_ISA_REV and use to simplify other code

  Minor cleanups:
   - DTS: boston/ci20: Unit name cleanups and correction
   - kdump: Make the default for PHYSICAL_START always 64-bit
   - constify gpio_led in Alchemy, AR7, and TXX9
   - silence a couple of W=1 warnings
   - remove duplicate includes

  Platform support:
  Generic platform:
   - add support for Microsemi Ocelot
   - dt-bindings: Add vendor prefix for Microsemi Corporation
   - dt-bindings: Add bindings for Microsemi SoCs
   - add ocelot SoC & PCB123 board DTS files
   - MAINTAINERS: Add entry for Microsemi MIPS SoCs
   - enable crc32-mips on r6 configs

  ath79:
   - fix AR724X_PLL_REG_PCIE_CONFIG offset

  BCM47xx:
   - firmware: Use mac_pton() for MAC address parsing
   - add Luxul XAP1500/XWR1750 WiFi LEDs
   - use standard reset button for Luxul XWR-1750

  BMIPS:
   - enable CONFIG_BRCMSTB_PM in bmips_stb_defconfig for build coverage
   - add STB PM, wake-up timer, watchdog DT nodes

  Octeon:
   - drop '.' after newlines in printk calls

  ralink:
   - pci-mt7621: Enable PCIe on MT7688"

* tag 'mips_4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/jhogan/mips: (37 commits)
  MIPS: BCM47XX: Use standard reset button for Luxul XWR-1750
  MIPS: BCM47XX: Add Luxul XAP1500/XWR1750 WiFi LEDs
  MIPS: Make the default for PHYSICAL_START always 64-bit
  MIPS: Use the entry point from the ELF file header
  MAINTAINERS: Add entry for Microsemi MIPS SoCs
  MIPS: generic: Add support for Microsemi Ocelot
  MIPS: mscc: Add ocelot PCB123 device tree
  MIPS: mscc: Add ocelot dtsi
  dt-bindings: mips: Add bindings for Microsemi SoCs
  dt-bindings: Add vendor prefix for Microsemi Corporation
  MIPS: ath79: Fix AR724X_PLL_REG_PCIE_CONFIG offset
  MIPS: pci-mt7620: Enable PCIe on MT7688
  MIPS: pm-cps: Block system suspend when a JTAG probe is present
  MIPS: VDSO: Replace __mips_isa_rev with MIPS_ISA_REV
  MIPS: BPF: Replace __mips_isa_rev with MIPS_ISA_REV
  MIPS: cpu-features.h: Replace __mips_isa_rev with MIPS_ISA_REV
  MIPS: Introduce isa-rev.h to define MIPS_ISA_REV
  MIPS: Hang more efficiently on halt/powerdown/restart
  FIRMWARE: bcm47xx_nvram: Replace mac address parsing
  MIPS: BMIPS: Add Broadcom STB watchdog nodes
  ...

1 files changed, 62 insertions, 6 deletions

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();
 }