ARM: tegra30: add CPU hotplug support
Hotplug function put CPUs in offline or online state at runtime.
When the CPU been put in the offline state, it was been clock and
power gated. Except primary CPU other CPUs can be hotplugged.
Based on the work by:
Scott Williams <scwilliams@nvidia.com>
Colin Cross <ccross@android.com>
Gary King <gking@nvidia.com>
Signed-off-by: Joseph Lo <josephl@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
diff --git a/arch/arm/mach-tegra/sleep-t30.S b/arch/arm/mach-tegra/sleep-t30.S
new file mode 100644
index 0000000..777d9ce
--- /dev/null
+++ b/arch/arm/mach-tegra/sleep-t30.S
@@ -0,0 +1,107 @@
+/*
+ * Copyright (c) 2012, NVIDIA Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/linkage.h>
+
+#include <asm/assembler.h>
+
+#include <mach/iomap.h>
+
+#include "sleep.h"
+#include "flowctrl.h"
+
+#define TEGRA30_POWER_HOTPLUG_SHUTDOWN (1 << 27) /* Hotplug shutdown */
+
+#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_PM_SLEEP)
+/*
+ * tegra30_hotplug_shutdown(void)
+ *
+ * Powergates the current CPU.
+ * Should never return.
+ */
+ENTRY(tegra30_hotplug_shutdown)
+ /* Turn off SMP coherency */
+ exit_smp r4, r5
+
+ /* Powergate this CPU */
+ mov r0, #TEGRA30_POWER_HOTPLUG_SHUTDOWN
+ bl tegra30_cpu_shutdown
+ mov pc, lr @ should never get here
+ENDPROC(tegra30_hotplug_shutdown)
+
+/*
+ * tegra30_cpu_shutdown(unsigned long flags)
+ *
+ * Puts the current CPU in wait-for-event mode on the flow controller
+ * and powergates it -- flags (in R0) indicate the request type.
+ * Must never be called for CPU 0.
+ *
+ * corrupts r0-r4, r12
+ */
+ENTRY(tegra30_cpu_shutdown)
+ cpu_id r3
+ cmp r3, #0
+ moveq pc, lr @ Must never be called for CPU 0
+
+ ldr r12, =TEGRA_FLOW_CTRL_VIRT
+ cpu_to_csr_reg r1, r3
+ add r1, r1, r12 @ virtual CSR address for this CPU
+ cpu_to_halt_reg r2, r3
+ add r2, r2, r12 @ virtual HALT_EVENTS address for this CPU
+
+ /*
+ * Clear this CPU's "event" and "interrupt" flags and power gate
+ * it when halting but not before it is in the "WFE" state.
+ */
+ movw r12, \
+ FLOW_CTRL_CSR_INTR_FLAG | FLOW_CTRL_CSR_EVENT_FLAG | \
+ FLOW_CTRL_CSR_ENABLE
+ mov r4, #(1 << 4)
+ orr r12, r12, r4, lsl r3
+ str r12, [r1]
+
+ /* Halt this CPU. */
+ mov r3, #0x400
+delay_1:
+ subs r3, r3, #1 @ delay as a part of wfe war.
+ bge delay_1;
+ cpsid a @ disable imprecise aborts.
+ ldr r3, [r1] @ read CSR
+ str r3, [r1] @ clear CSR
+ tst r0, #TEGRA30_POWER_HOTPLUG_SHUTDOWN
+ movne r3, #FLOW_CTRL_WAITEVENT @ For hotplug
+ str r3, [r2]
+ ldr r0, [r2]
+ b wfe_war
+
+__cpu_reset_again:
+ dsb
+ .align 5
+ wfe @ CPU should be power gated here
+wfe_war:
+ b __cpu_reset_again
+
+ /*
+ * 38 nop's, which fills reset of wfe cache line and
+ * 4 more cachelines with nop
+ */
+ .rept 38
+ nop
+ .endr
+ b . @ should never get here
+
+ENDPROC(tegra30_cpu_shutdown)
+#endif