ARM: tegra30: cpuidle: add powered-down state for secondary CPUs

This supports power-gated idle on secondary CPUs for Tegra30. The
secondary CPUs can go into powered-down state independently. When
CPU goes into this state, it saves it's contexts and puts itself
to flow controlled WFI state. After that, it will been power gated.

Be aware of that, you may see the legacy power state "LP2" in the
code which is exactly the same meaning of "CPU power down".

Based on the work by:
Scott Williams <scwilliams@nvidia.com>

Signed-off-by: Joseph Lo <josephl@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>

8 files changed, 253 insertions, 0 deletions

diff --git a/arch/arm/mach-tegra/Makefile b/arch/arm/mach-tegra/Makefile
index 488159eaa42..0979e8bba78 100644
--- a/arch/arm/mach-tegra/Makefile
+++ b/arch/arm/mach-tegra/Makefile
@@ -8,6 +8,7 @@ obj-y					+= pmc.o
 obj-y                                   += flowctrl.o
 obj-y                                   += powergate.o
 obj-y                                   += apbio.o
+obj-y                                   += pm.o
 obj-$(CONFIG_CPU_IDLE)                  += cpuidle.o
 obj-$(CONFIG_CPU_IDLE)                  += sleep.o
 obj-$(CONFIG_ARCH_TEGRA_2x_SOC)         += tegra20_clocks.o
diff --git a/arch/arm/mach-tegra/cpuidle-tegra30.c b/arch/arm/mach-tegra/cpuidle-tegra30.c
index 37e75512f69..cc48d7fa335 100644
--- a/arch/arm/mach-tegra/cpuidle-tegra30.c
+++ b/arch/arm/mach-tegra/cpuidle-tegra30.c
@@ -22,21 +22,107 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/cpuidle.h>
+#include <linux/cpu_pm.h>
+#include <linux/clockchips.h>
 
 #include <asm/cpuidle.h>
+#include <asm/proc-fns.h>
+#include <asm/suspend.h>
+#include <asm/smp_plat.h>
+
+#include "pm.h"
+#include "sleep.h"
+
+#ifdef CONFIG_PM_SLEEP
+static int tegra30_idle_lp2(struct cpuidle_device *dev,
+                            struct cpuidle_driver *drv,
+                            int index);
+#endif
 
 static struct cpuidle_driver tegra_idle_driver = {
         .name = "tegra_idle",
         .owner = THIS_MODULE,
         .en_core_tk_irqen = 1,
+#ifdef CONFIG_PM_SLEEP
+        .state_count = 2,
+#else
         .state_count = 1,
+#endif
         .states = {
                 [0] = ARM_CPUIDLE_WFI_STATE_PWR(600),
+#ifdef CONFIG_PM_SLEEP
+                [1] = {
+                        .enter                  = tegra30_idle_lp2,
+                        .exit_latency           = 2000,
+                        .target_residency       = 2200,
+                        .power_usage            = 0,
+                        .flags                  = CPUIDLE_FLAG_TIME_VALID,
+                        .name                   = "powered-down",
+                        .desc                   = "CPU power gated",
+                },
+#endif
         },
 };
 
 static DEFINE_PER_CPU(struct cpuidle_device, tegra_idle_device);
 
+#ifdef CONFIG_PM_SLEEP
+#ifdef CONFIG_SMP
+static bool tegra30_cpu_core_power_down(struct cpuidle_device *dev,
+                                        struct cpuidle_driver *drv,
+                                        int index)
+{
+        clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu);
+
+        smp_wmb();
+
+        save_cpu_arch_register();
+
+        cpu_suspend(0, tegra30_sleep_cpu_secondary_finish);
+
+        restore_cpu_arch_register();
+
+        clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &dev->cpu);
+
+        return true;
+}
+#else
+static inline bool tegra30_cpu_core_power_down(struct cpuidle_device *dev,
+                                               struct cpuidle_driver *drv,
+                                               int index)
+{
+        return true;
+}
+#endif
+
+static int __cpuinit tegra30_idle_lp2(struct cpuidle_device *dev,
+                                      struct cpuidle_driver *drv,
+                                      int index)
+{
+        u32 cpu = is_smp() ? cpu_logical_map(dev->cpu) : dev->cpu;
+        bool entered_lp2 = false;
+
+        local_fiq_disable();
+
+        tegra_set_cpu_in_lp2(cpu);
+        cpu_pm_enter();
+
+        if (cpu == 0)
+                cpu_do_idle();
+        else
+                entered_lp2 = tegra30_cpu_core_power_down(dev, drv, index);
+
+        cpu_pm_exit();
+        tegra_clear_cpu_in_lp2(cpu);
+
+        local_fiq_enable();
+
+        smp_rmb();
+
+        return (entered_lp2) ? index : 0;
+}
+#endif
+
 int __init tegra30_cpuidle_init(void)
 {
         int ret;
diff --git a/arch/arm/mach-tegra/pm.c b/arch/arm/mach-tegra/pm.c
new file mode 100644
index 00000000000..f88595abc47
--- /dev/null
+++ b/arch/arm/mach-tegra/pm.c
@@ -0,0 +1,74 @@
+/*
+ * CPU complex suspend & resume functions for Tegra SoCs
+ *
+ * Copyright (c) 2009-2012, 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/kernel.h>
+#include <linux/spinlock.h>
+#include <linux/io.h>
+#include <linux/cpumask.h>
+
+#include "iomap.h"
+#include "reset.h"
+
+#ifdef CONFIG_PM_SLEEP
+static unsigned int g_diag_reg;
+static DEFINE_SPINLOCK(tegra_lp2_lock);
+
+void save_cpu_arch_register(void)
+{
+        /* read diagnostic register */
+        asm("mrc p15, 0, %0, c15, c0, 1" : "=r"(g_diag_reg) : : "cc");
+        return;
+}
+
+void restore_cpu_arch_register(void)
+{
+        /* write diagnostic register */
+        asm("mcr p15, 0, %0, c15, c0, 1" : : "r"(g_diag_reg) : "cc");
+        return;
+}
+
+void __cpuinit tegra_clear_cpu_in_lp2(int phy_cpu_id)
+{
+        u32 *cpu_in_lp2 = tegra_cpu_lp2_mask;
+
+        spin_lock(&tegra_lp2_lock);
+
+        BUG_ON(!(*cpu_in_lp2 & BIT(phy_cpu_id)));
+        *cpu_in_lp2 &= ~BIT(phy_cpu_id);
+
+        spin_unlock(&tegra_lp2_lock);
+}
+
+bool __cpuinit tegra_set_cpu_in_lp2(int phy_cpu_id)
+{
+        bool last_cpu = false;
+        cpumask_t *cpu_lp2_mask = tegra_cpu_lp2_mask;
+        u32 *cpu_in_lp2 = tegra_cpu_lp2_mask;
+
+        spin_lock(&tegra_lp2_lock);
+
+        BUG_ON((*cpu_in_lp2 & BIT(phy_cpu_id)));
+        *cpu_in_lp2 |= BIT(phy_cpu_id);
+
+        if ((phy_cpu_id == 0) && cpumask_equal(cpu_lp2_mask, cpu_online_mask))
+                last_cpu = true;
+
+        spin_unlock(&tegra_lp2_lock);
+        return last_cpu;
+}
+#endif
diff --git a/arch/arm/mach-tegra/pm.h b/arch/arm/mach-tegra/pm.h
new file mode 100644
index 00000000000..bcfc45faad7
--- /dev/null
+++ b/arch/arm/mach-tegra/pm.h
@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2010 Google, Inc.
+ * Copyright (c) 2010-2012 NVIDIA Corporation. All rights reserved.
+ *
+ * Author:
+ *      Colin Cross <ccross@google.com>
+ *
+ * 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/>.
+ */
+
+#ifndef _MACH_TEGRA_PM_H_
+#define _MACH_TEGRA_PM_H_
+
+void save_cpu_arch_register(void);
+void restore_cpu_arch_register(void);
+
+void tegra_clear_cpu_in_lp2(int phy_cpu_id);
+bool tegra_set_cpu_in_lp2(int phy_cpu_id);
+
+#endif /* _MACH_TEGRA_PM_H_ */
diff --git a/arch/arm/mach-tegra/reset.h b/arch/arm/mach-tegra/reset.h
index de88bf851dd..c90d8e9c4ad 100644
--- a/arch/arm/mach-tegra/reset.h
+++ b/arch/arm/mach-tegra/reset.h
@@ -29,6 +29,8 @@
 
 #ifndef __ASSEMBLY__
 
+#include "irammap.h"
+
 extern unsigned long __tegra_cpu_reset_handler_data[TEGRA_RESET_DATA_SIZE];
 
 void __tegra_cpu_reset_handler_start(void);
@@ -36,6 +38,13 @@ void __tegra_cpu_reset_handler(void);
 void __tegra_cpu_reset_handler_end(void);
 void tegra_secondary_startup(void);
 
+#ifdef CONFIG_PM_SLEEP
+#define tegra_cpu_lp2_mask \
+        (IO_ADDRESS(TEGRA_IRAM_BASE + TEGRA_IRAM_RESET_HANDLER_OFFSET + \
+        ((u32)&__tegra_cpu_reset_handler_data[TEGRA_RESET_MASK_LP2] - \
+         (u32)__tegra_cpu_reset_handler_start)))
+#endif
+
 #define tegra_cpu_reset_handler_offset \
                 ((u32)__tegra_cpu_reset_handler - \
                  (u32)__tegra_cpu_reset_handler_start)
diff --git a/arch/arm/mach-tegra/sleep-tegra30.S b/arch/arm/mach-tegra/sleep-tegra30.S
index be7614b7c5c..59984d71848 100644
--- a/arch/arm/mach-tegra/sleep-tegra30.S
+++ b/arch/arm/mach-tegra/sleep-tegra30.S
@@ -17,6 +17,7 @@
 #include <linux/linkage.h>
 
 #include <asm/assembler.h>
+#include <asm/asm-offsets.h>
 
 #include "sleep.h"
 #include "flowctrl.h"
@@ -80,6 +81,7 @@ delay_1:
         ldr     r3, [r1]                        @ read CSR
         str     r3, [r1]                        @ clear CSR
         tst     r0, #TEGRA30_POWER_HOTPLUG_SHUTDOWN
+        moveq   r3, #FLOW_CTRL_WAIT_FOR_INTERRUPT       @ For LP2
         movne   r3, #FLOW_CTRL_WAITEVENT                @ For hotplug
         str     r3, [r2]
         ldr     r0, [r2]
@@ -103,3 +105,23 @@ wfe_war:
 
 ENDPROC(tegra30_cpu_shutdown)
 #endif
+
+#ifdef CONFIG_PM_SLEEP
+/*
+ * tegra30_sleep_cpu_secondary_finish(unsigned long v2p)
+ *
+ * Enters LP2 on secondary CPU by exiting coherency and powergating the CPU.
+ */
+ENTRY(tegra30_sleep_cpu_secondary_finish)
+        mov     r7, lr
+
+        /* Flush and disable the L1 data cache */
+        bl      tegra_disable_clean_inv_dcache
+
+        /* Powergate this CPU. */
+        mov     r0, #0                          @ power mode flags (!hotplug)
+        bl      tegra30_cpu_shutdown
+        mov     r0, #1                          @ never return here
+        mov     pc, r7
+ENDPROC(tegra30_sleep_cpu_secondary_finish)
+#endif
diff --git a/arch/arm/mach-tegra/sleep.S b/arch/arm/mach-tegra/sleep.S
index 08e9481c049..91548a77dd9 100644
--- a/arch/arm/mach-tegra/sleep.S
+++ b/arch/arm/mach-tegra/sleep.S
@@ -25,9 +25,38 @@
 #include <linux/linkage.h>
 
 #include <asm/assembler.h>
+#include <asm/cp15.h>
 
 #include "iomap.h"
 
 #include "flowctrl.h"
 #include "sleep.h"
 
+#ifdef CONFIG_PM_SLEEP
+/*
+ * tegra_disable_clean_inv_dcache
+ *
+ * disable, clean & invalidate the D-cache
+ *
+ * Corrupted registers: r1-r3, r6, r8, r9-r11
+ */
+ENTRY(tegra_disable_clean_inv_dcache)
+        stmfd   sp!, {r0, r4-r5, r7, r9-r11, lr}
+        dmb                                     @ ensure ordering
+
+        /* Disable the D-cache */
+        mrc     p15, 0, r2, c1, c0, 0
+        bic     r2, r2, #CR_C
+        mcr     p15, 0, r2, c1, c0, 0
+        isb
+
+        /* Flush the D-cache */
+        bl      v7_flush_dcache_louis
+
+        /* Trun off coherency */
+        exit_smp r4, r5
+
+        ldmfd   sp!, {r0, r4-r5, r7, r9-r11, pc}
+ENDPROC(tegra_disable_clean_inv_dcache)
+
+#endif
diff --git a/arch/arm/mach-tegra/sleep.h b/arch/arm/mach-tegra/sleep.h
index addb83f5bc7..bacf549bd54 100644
--- a/arch/arm/mach-tegra/sleep.h
+++ b/arch/arm/mach-tegra/sleep.h
@@ -82,5 +82,7 @@ static inline void tegra20_hotplug_init(void) {}
 static inline void tegra30_hotplug_init(void) {}
 #endif
 
+int tegra30_sleep_cpu_secondary_finish(unsigned long);
+
 #endif
 #endif