ARM: TC2 big.LITTLE CPU idle driver

drivers/cpuidle/cpuidle-big_little.c line 72

Quoted 6 lines · Lorenzo Pieralisi

drivers/cpuidle/cpuidle-big_little.c new file +6 -0

+static int notrace bl_powerdown_finisher(unsigned long arg)
+{
+	/* MCPM works with HW CPU identifiers */
+	unsigned int mpidr = read_cpuid_mpidr();
+	unsigned int cluster = (mpidr >> 8) & 0xf;
+	unsigned int cpu = mpidr & 0xf;

You probably want to use the MPIDR_AFFINITY_LEVEL() macro here.

The big.LITTLE architecture is composed of two clusters of cpus. One cluster contains less powerful but more energy efficient processors and the other cluster groups the powerful but energy-intensive cpus.

The TC2 testchip implements two clusters of CPUs (A7 and A15 clusters in a big.LITTLE configuration) connected through a CCI interconnect that manages coherency of their respective L2 caches and intercluster distributed virtual memory messages (DVM).

TC2 testchip integrates a power controller that manages cores resets, wake-up IRQs and cluster low-power states. Power states are managed at cluster level, which means that voltage is removed from a cluster iff all cores in a cluster are in a wfi state. Single cores can enter a reset state which is identical to wfi in terms of power consumption but simplifies the way cluster states are entered.

This patch provides a multiple driver CPU idle implementation for TC2 which paves the way for a generic big.LITTLE idle driver for all upcoming big.LITTLE based systems on chip.

The driver relies on the MCPM infrastructure to coordinate and manage core power states; in particular MCPM allows to suspend specific cores and hides the CPUs coordination required to shut-down clusters of CPUs.

Power down sequences for the respective clusters are implemented in the MCPM TC2 backend, with all code needed to clean caches and exit coherency.

The multiple driver CPU idle infrastructure allows to define different C-states for big and little cores, determined at boot by checking the part id of the possible CPUs and initializing the respective logical masks in the big and little drivers.

Current big.little systems are composed of A7 and A15 clusters, as implemented in TC2, but in the future that may change and the driver will have evolve to retrieve what is a 'big' cpu and what is a 'little' cpu in order to build the correct topology.

Cc Kevin Hilman <[email protected]>

Cc Amit Kucheria <[email protected]>

Cc Olof Johansson <[email protected]>

Cc Nicolas Pitre <[email protected]>

Cc Rafael J. Wysocki <[email protected]>

Signed-off-by Daniel Lezcano <[email protected]>

Signed-off-by Lorenzo Pieralisi <[email protected]>

---
 MAINTAINERS                          |   9 ++
 drivers/cpuidle/Kconfig              |  10 ++
 drivers/cpuidle/Makefile             |   1 +
 drivers/cpuidle/cpuidle-big_little.c | 187 +++++++++++++++++++++++++++++++++++
 4 files changed, 207 insertions(+)
 create mode 100644 drivers/cpuidle/cpuidle-big_little.c

MAINTAINERS +9 -0

index bf61e04..01f1b3d 100644
@@ -2263,6 +2263,15 @@ F:	drivers/cpufreq/arm_big_little.h
 F:	drivers/cpufreq/arm_big_little.c
 F:	drivers/cpufreq/arm_big_little_dt.c
 
+CPUIDLE DRIVER - ARM BIG LITTLE
+M:      Lorenzo Pieralisi <[email protected]>
+M:      Daniel Lezcano <[email protected]>
+L:      linux-pm at vger.kernel.org
+L:      linux-arm-kernel at lists.infradead.org
+T:      git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git
+S:      Maintained
+F:      drivers/cpuidle/cpuidle-big_little.c
+
 CPUIDLE DRIVERS
 M:	Rafael J. Wysocki <[email protected]>
 M:	Daniel Lezcano <[email protected]>

drivers/cpuidle/Kconfig +10 -0

index 0e2cd5c..0f86587 100644
@@ -42,6 +42,16 @@ config CPU_IDLE_ZYNQ
 	help
 	  Select this to enable cpuidle on Xilinx Zynq processors.
 
+config CPU_IDLE_BIG_LITTLE
+	bool "Support for ARM big.LITTLE processors"
+	depends on ARCH_VEXPRESS_TC2_PM
+	select ARM_CPU_SUSPEND
+	select CPU_IDLE_MULTIPLE_DRIVERS
+	help
+	  Select this option to enable CPU idle driver for big.LITTLE based
+	  ARM systems. Driver manages CPUs coordination through MCPM and
+	  define different C-states for little and big cores through the
+	  multiple CPU idle drivers infrastructure.
 endif
 
 config ARCH_NEEDS_CPU_IDLE_COUPLED

drivers/cpuidle/Makefile +1 -0

index 8767a7b..3b6445c 100644
@@ -8,3 +8,4 @@ obj-$(CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED) += coupled.o
 obj-$(CONFIG_CPU_IDLE_CALXEDA) += cpuidle-calxeda.o
 obj-$(CONFIG_ARCH_KIRKWOOD) += cpuidle-kirkwood.o
 obj-$(CONFIG_CPU_IDLE_ZYNQ) += cpuidle-zynq.o
+obj-$(CONFIG_CPU_IDLE_BIG_LITTLE) += cpuidle-big_little.o

drivers/cpuidle/cpuidle-big_little.c new file +106 -0

new file mode 100644
index 0000000..98cb375
@@ -0,0 +1,187 @@
+/*
+ * Copyright (c) 2013 ARM/Linaro
+ *
+ * Authors: Daniel Lezcano <[email protected]>
+ *          Lorenzo Pieralisi <[email protected]>
+ *          Nicolas Pitre <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Maintainer: Lorenzo Pieralisi <[email protected]>
+ * Maintainer: Daniel Lezcano <[email protected]>
+ */
+#include <linux/cpuidle.h>
+#include <linux/cpu_pm.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+
+#include <asm/cpu.h>
+#include <asm/cputype.h>
+#include <asm/cpuidle.h>
+#include <asm/mcpm.h>
+#include <asm/smp_plat.h>
+#include <asm/suspend.h>
+
+static int bl_enter_powerdown(struct cpuidle_device *dev,
+			      struct cpuidle_driver *drv, int idx);
+
+static struct cpuidle_driver bl_idle_little_driver = {
+	.name = "little_idle",
+	.owner = THIS_MODULE,
+	.states[0] = ARM_CPUIDLE_WFI_STATE,
+	.states[1] = {
+		.enter			= bl_enter_powerdown,
+		.exit_latency		= 1000,
+		.target_residency	= 3500,
+		.flags			= CPUIDLE_FLAG_TIME_VALID |
+					  CPUIDLE_FLAG_TIMER_STOP,
+		.name			= "C1",
+		.desc			= "ARM little-cluster power down",
+	},
+	.state_count = 2,
+};
+
+static struct cpuidle_driver bl_idle_big_driver = {
+	.name = "big_idle",
+	.owner = THIS_MODULE,
+	.states[0] = ARM_CPUIDLE_WFI_STATE,
+	.states[1] = {
+		.enter			= bl_enter_powerdown,
+		.exit_latency		= 1000,
+		.target_residency	= 3000,
+		.flags			= CPUIDLE_FLAG_TIME_VALID |
+					  CPUIDLE_FLAG_TIMER_STOP,
+		.name			= "C1",
+		.desc			= "ARM big-cluster power down",
+	},
+	.state_count = 2,
+};
+
+/*
+ * notrace prevents trace shims from getting inserted where they
+ * should not. Global jumps and ldrex/strex must not be inserted
+ * in power down sequences where caches and MMU may be turned off.
+ */
+static int notrace bl_powerdown_finisher(unsigned long arg)
+{
+	/* MCPM works with HW CPU identifiers */
+	unsigned int mpidr = read_cpuid_mpidr();
+	unsigned int cluster = (mpidr >> 8) & 0xf;
+	unsigned int cpu = mpidr & 0xf;
+
+	mcpm_set_entry_vector(cpu, cluster, cpu_resume);
+	/*
+	 * Residency value passed to mcpm_cpu_suspend back-end
+	 * has to be given clear semantics. Set to 0 as a
+	 * temporary value.
+	 */
+	mcpm_cpu_suspend(0);
+	/* return value != 0 means failure */
+	return 1;
+}
+
+/**
+ * bl_enter_powerdown - Programs CPU to enter the specified state
+ * @dev: cpuidle device
+ * @drv: The target state to be programmed
+ * @idx: state index
+ *
+ * Called from the CPUidle framework to program the device to the
+ * specified target state selected by the governor.
+ */
+static int bl_enter_powerdown(struct cpuidle_device *dev,
+				struct cpuidle_driver *drv, int idx)
+{
+	struct timespec ts_preidle, ts_postidle, ts_idle;
+	int ret;
+
+	/* Used to keep track of the total time in idle */
+	getnstimeofday(&ts_preidle);
+
+	cpu_pm_enter();
+
+	ret = cpu_suspend(0, bl_powerdown_finisher);
+	/* signals the MCPM core that CPU is out of low power state */

drivers/cpuidle/cpuidle-big_little.c new file +71 -0

+	return idx;
+}
+
+static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int cpu_id)
+{
+	struct cpuinfo_arm *cpu_info;
+	struct cpumask *cpumask;
+	unsigned long cpuid;
+	int cpu;
+
+	cpumask = kzalloc(cpumask_size(), GFP_KERNEL);
+	if (!cpumask)
+		return -ENOMEM;
+
+	for_each_possible_cpu(cpu) {
+		cpu_info = &per_cpu(cpu_data, cpu);
+		cpuid = is_smp() ? cpu_info->cpuid : read_cpuid_id();
+
+		/* read cpu id part number */
+		if ((cpuid & 0xFFF0) == cpu_id)
+			cpumask_set_cpu(cpu, cpumask);
+	}
+
+	drv->cpumask = cpumask;
+
+	return 0;
+}
+
+static int __init bl_idle_init(void)
+{
+	int ret;
+	/*
+	 * Initialize the driver just for a compliant set of machines
+	 */
+	if (!of_machine_is_compatible("arm,vexpress,v2p-ca15_a7"))
+		return -ENODEV;
+	/*
+	 * For now the differentiation between little and big cores
+	 * is based on the part number. A7 cores are considered little
+	 * cores, A15 are considered big cores. This distinction may
+	 * evolve in the future with a more generic matching approach.
+	 */
+	ret = bl_idle_driver_init(&bl_idle_little_driver,
+				  ARM_CPU_PART_CORTEX_A7);
+	if (ret)
+		return ret;
+
+	ret = bl_idle_driver_init(&bl_idle_big_driver, ARM_CPU_PART_CORTEX_A15);
+	if (ret)
+		goto out_uninit_little;
+
+	ret = cpuidle_register(&bl_idle_little_driver, NULL);
+	if (ret)
+		goto out_uninit_big;
+
+	ret = cpuidle_register(&bl_idle_big_driver, NULL);
+	if (ret)
+		goto out_unregister_little;
+
+	return 0;
+
+out_unregister_little:
+	cpuidle_unregister(&bl_idle_little_driver);
+out_uninit_big:
+	kfree(bl_idle_big_driver.cpumask);
+out_uninit_little:
+	kfree(bl_idle_little_driver.cpumask);
+
+	return ret;
+}
+device_initcall(bl_idle_init);

On 07/25/2013 01:14 PM, Lorenzo Pieralisi wrote:

Quoted 27 lines

drivers/cpuidle/cpuidle-big_little.c new file +27 -0

+/**
+ * bl_enter_powerdown - Programs CPU to enter the specified state
+ * @dev: cpuidle device
+ * @drv: The target state to be programmed
+ * @idx: state index
+ *
+ * Called from the CPUidle framework to program the device to the
+ * specified target state selected by the governor.
+ */
+static int bl_enter_powerdown(struct cpuidle_device *dev,
+				struct cpuidle_driver *drv, int idx)
+{
+	struct timespec ts_preidle, ts_postidle, ts_idle;
+	int ret;
+
+	/* Used to keep track of the total time in idle */
+	getnstimeofday(&ts_preidle);
+
+	cpu_pm_enter();
+
+	ret = cpu_suspend(0, bl_powerdown_finisher);
+	/* signals the MCPM core that CPU is out of low power state */
+	mcpm_cpu_powered_up();
+
+	cpu_pm_exit();
+
+	getnstimeofday(&ts_postidle);

drivers/cpuidle/cpuidle-big_little.c line 116

Quoted 5 lines

drivers/cpuidle/cpuidle-big_little.c new file +5 -0

+	ts_idle = timespec_sub(ts_postidle, ts_preidle);
+
+	dev->last_residency = ts_idle.tv_nsec / NSEC_PER_USEC +
+					ts_idle.tv_sec * USEC_PER_SEC;
+	local_irq_enable();

time computation and local irq enablement are handled by the cpuidle framework.

The big.LITTLE architecture is composed of two clusters of cpus. One cluster contains less powerful but more energy efficient processors and the other cluster groups the powerful but energy-intensive cpus.

The TC2 testchip implements two clusters of CPUs (A7 and A15 clusters in a big.LITTLE configuration) connected through a CCI interconnect that manages coherency of their respective L2 caches and intercluster distributed virtual memory messages (DVM).

TC2 testchip integrates a power controller that manages cores resets, wake-up IRQs and cluster low-power states. Power states are managed at cluster level, which means that voltage is removed from a cluster iff all cores in a cluster are in a wfi state. Single cores can enter a reset state which is identical to wfi in terms of power consumption but simplifies the way cluster states are entered.

This patch provides a multiple driver CPU idle implementation for TC2 which paves the way for a generic big.LITTLE idle driver for all upcoming big.LITTLE based systems on chip.

The driver relies on the MCPM infrastructure to coordinate and manage core power states; in particular MCPM allows to suspend specific cores and hides the CPUs coordination required to shut-down clusters of CPUs.

Power down sequences for the respective clusters are implemented in the MCPM TC2 backend, with all code needed to clean caches and exit coherency.

The multiple driver CPU idle infrastructure allows to define different C-states for big and little cores, determined at boot by checking the part id of the possible CPUs and initializing the respective logical masks in the big and little drivers.

Current big.little systems are composed of A7 and A15 clusters, as implemented in TC2, but in the future that may change and the driver will have evolve to retrieve what is a 'big' cpu and what is a 'little' cpu in order to build the correct topology.

Cc Kevin Hilman <[email protected]>

Cc Amit Kucheria <[email protected]>

Cc Olof Johansson <[email protected]>

Cc Nicolas Pitre <[email protected]>

Cc Rafael J. Wysocki <[email protected]>

Signed-off-by Daniel Lezcano <[email protected]>

Signed-off-by Lorenzo Pieralisi <[email protected]>

drivers/cpuidle/cpuidle-big_little.c new file +15 -0

+	/* return value != 0 means failure */
+	return 1;
+}
+
+/**
+ * bl_enter_powerdown - Programs CPU to enter the specified state
+ * @dev: cpuidle device
+ * @drv: The target state to be programmed
+ * @idx: state index
+ *
+ * Called from the CPUidle framework to program the device to the
+ * specified target state selected by the governor.
+ */
+static int bl_enter_powerdown(struct cpuidle_device *dev,
+				struct cpuidle_driver *drv, int idx)

drivers/cpuidle/cpuidle-big_little.c new file +21 -0

+	return idx;
+}
+
+static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int cpu_id)
+{
+	struct cpuinfo_arm *cpu_info;
+	struct cpumask *cpumask;
+	unsigned long cpuid;
+	int cpu;
+
+	cpumask = kzalloc(cpumask_size(), GFP_KERNEL);
+	if (!cpumask)
+		return -ENOMEM;
+
+	for_each_possible_cpu(cpu) {
+		cpu_info = &per_cpu(cpu_data, cpu);
+		cpuid = is_smp() ? cpu_info->cpuid : read_cpuid_id();
+
+		/* read cpu id part number */
+		if ((cpuid & 0xFFF0) == cpu_id)
+			cpumask_set_cpu(cpu, cpumask);

drivers/cpuidle/cpuidle-big_little.c new file +30 -0

+	/*
+	 * Initialize the driver just for a compliant set of machines
+	 */
+	if (!of_machine_is_compatible("arm,vexpress,v2p-ca15_a7"))
+		return -ENODEV;
+	/*
+	 * For now the differentiation between little and big cores
+	 * is based on the part number. A7 cores are considered little
+	 * cores, A15 are considered big cores. This distinction may
+	 * evolve in the future with a more generic matching approach.
+	 */
+	ret = bl_idle_driver_init(&bl_idle_little_driver,
+				  ARM_CPU_PART_CORTEX_A7);
+	if (ret)
+		return ret;
+
+	ret = bl_idle_driver_init(&bl_idle_big_driver, ARM_CPU_PART_CORTEX_A15);
+	if (ret)
+		goto out_uninit_little;
+
+	ret = cpuidle_register(&bl_idle_little_driver, NULL);
+	if (ret)
+		goto out_uninit_big;
+
+	ret = cpuidle_register(&bl_idle_big_driver, NULL);
+	if (ret)
+		goto out_unregister_little;
+
+	return 0;
+

Hi Lorenzo,

Quoted 37 lines · Lorenzo Pieralisi

The big.LITTLE architecture is composed of two clusters of cpus. One cluster contains less powerful but more energy efficient processors and the other cluster groups the powerful but energy-intensive cpus.

The TC2 testchip implements two clusters of CPUs (A7 and A15 clusters in a big.LITTLE configuration) connected through a CCI interconnect that manages coherency of their respective L2 caches and intercluster distributed virtual memory messages (DVM).

TC2 testchip integrates a power controller that manages cores resets, wake-up IRQs and cluster low-power states. Power states are managed at cluster level, which means that voltage is removed from a cluster iff all cores in a cluster are in a wfi state. Single cores can enter a reset state which is identical to wfi in terms of power consumption but simplifies the way cluster states are entered.

This patch provides a multiple driver CPU idle implementation for TC2 which paves the way for a generic big.LITTLE idle driver for all upcoming big.LITTLE based systems on chip.

The driver relies on the MCPM infrastructure to coordinate and manage core power states; in particular MCPM allows to suspend specific cores and hides the CPUs coordination required to shut-down clusters of CPUs.

Power down sequences for the respective clusters are implemented in the MCPM TC2 backend, with all code needed to clean caches and exit coherency.

The multiple driver CPU idle infrastructure allows to define different C-states for big and little cores, determined at boot by checking the part id of the possible CPUs and initializing the respective logical masks in the big and little drivers.

Current big.little systems are composed of A7 and A15 clusters, as implemented in TC2, but in the future that may change and the driver will have evolve to retrieve what is a 'big' cpu and what is a 'little' cpu in order to build the correct topology.

Quoted 7 lines

Cc Kevin Hilman <[email protected]>

Cc Amit Kucheria <[email protected]>

Cc Olof Johansson <[email protected]>

Cc Nicolas Pitre <[email protected]>

Cc Rafael J. Wysocki <[email protected]>

Signed-off-by Daniel Lezcano <[email protected]>

Signed-off-by Lorenzo Pieralisi <[email protected]>

Some minor comments below, as well as some readability nits.

drivers/cpuidle/cpuidle-big_little.c line 20

Quoted 6 lines

drivers/cpuidle/cpuidle-big_little.c new file +6 -0

+#include <linux/cpuidle.h>
+#include <linux/cpu_pm.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+
+#include <asm/cpu.h>

from checkpatch: WARNING: Use #include <linux/cpu.h> instead of <asm/cpu.h>

drivers/cpuidle/cpuidle-big_little.c line 22

Quoted 2 lines

drivers/cpuidle/cpuidle-big_little.c new file +2 -0

+#include <asm/cputype.h>
+#include <asm/cpuidle.h>

You already have <linux/cpuidle.h>, this shouldn't be necessary.

drivers/cpuidle/cpuidle-big_little.c line 25

Quoted 3 lines

drivers/cpuidle/cpuidle-big_little.c new file +3 -0

+#include <asm/mcpm.h>
+#include <asm/smp_plat.h>
+#include <asm/suspend.h>

from checkpatch: WARNING: Use #include <linux/suspend.h> instead of <asm/suspend.h>

[...]

drivers/cpuidle/cpuidle-big_little.c line 37

Quoted 8 lines

drivers/cpuidle/cpuidle-big_little.c new file +8 -0

+static struct cpuidle_driver bl_idle_little_driver = {
+	.name = "little_idle",
+	.owner = THIS_MODULE,
+	.states[0] = ARM_CPUIDLE_WFI_STATE,
+	.states[1] = {
+		.enter			= bl_enter_powerdown,
+		.exit_latency		= 1000,
+		.target_residency	= 3500,

It would be good to have some comments about where these numbers come from. The changelog suggests this will be generic for all b.L platforms, but I suspect these values to have various SoC specific components to them. Eventually, we'll probably need some way specify these values, maybe from DT?

Same comment for the 'big' driver definition.

[...]

drivers/cpuidle/cpuidle-big_little.c line 74

Quoted 13 lines

drivers/cpuidle/cpuidle-big_little.c new file +13 -0

+/*
+ * notrace prevents trace shims from getting inserted where they
+ * should not. Global jumps and ldrex/strex must not be inserted
+ * in power down sequences where caches and MMU may be turned off.
+ */
+static int notrace bl_powerdown_finisher(unsigned long arg)
+{
+	/* MCPM works with HW CPU identifiers */
+	unsigned int mpidr = read_cpuid_mpidr();
+	unsigned int cluster = (mpidr >> 8) & 0xf;
+	unsigned int cpu = mpidr & 0xf;
+
+	mcpm_set_entry_vector(cpu, cluster, cpu_resume);

add blank line

drivers/cpuidle/cpuidle-big_little.c line 80

Quoted 6 lines

drivers/cpuidle/cpuidle-big_little.c new file +6 -0

+	/*
+	 * Residency value passed to mcpm_cpu_suspend back-end
+	 * has to be given clear semantics. Set to 0 as a
+	 * temporary value.
+	 */
+	mcpm_cpu_suspend(0);

add blank line

Quoted 19 lines

drivers/cpuidle/cpuidle-big_little.c new file +19 -0

+	/* return value != 0 means failure */
+	return 1;
+}
+
+/**
+ * bl_enter_powerdown - Programs CPU to enter the specified state
+ * @dev: cpuidle device
+ * @drv: The target state to be programmed
+ * @idx: state index
+ *
+ * Called from the CPUidle framework to program the device to the
+ * specified target state selected by the governor.
+ */
+static int bl_enter_powerdown(struct cpuidle_device *dev,
+				struct cpuidle_driver *drv, int idx)
+{
+	struct timespec ts_preidle, ts_postidle, ts_idle;
+	int ret;
+

drivers/cpuidle/cpuidle-big_little.c line 105

Quoted 6 lines

drivers/cpuidle/cpuidle-big_little.c new file +6 -0

+	/* Used to keep track of the total time in idle */
+	getnstimeofday(&ts_preidle);
+
+	cpu_pm_enter();
+
+	ret = cpu_suspend(0, bl_powerdown_finisher);

add blank line

Quoted 6 lines

drivers/cpuidle/cpuidle-big_little.c new file +6 -0

+	/* signals the MCPM core that CPU is out of low power state */
+	mcpm_cpu_powered_up();
+
+	cpu_pm_exit();
+
+	getnstimeofday(&ts_postidle);

drivers/cpuidle/cpuidle-big_little.c line 116

Quoted 5 lines

drivers/cpuidle/cpuidle-big_little.c new file +5 -0

+	ts_idle = timespec_sub(ts_postidle, ts_preidle);
+
+	dev->last_residency = ts_idle.tv_nsec / NSEC_PER_USEC +
+					ts_idle.tv_sec * USEC_PER_SEC;
+	local_irq_enable();

All of the residency caluclations and IRQ disable stuff is handled by the CPUidle core now, so should be removed from here.

Quoted 25 lines

drivers/cpuidle/cpuidle-big_little.c new file +25 -0

+	return idx;
+}
+
+static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int cpu_id)
+{
+	struct cpuinfo_arm *cpu_info;
+	struct cpumask *cpumask;
+	unsigned long cpuid;
+	int cpu;
+
+	cpumask = kzalloc(cpumask_size(), GFP_KERNEL);
+	if (!cpumask)
+		return -ENOMEM;
+
+	for_each_possible_cpu(cpu) {
+		cpu_info = &per_cpu(cpu_data, cpu);
+		cpuid = is_smp() ? cpu_info->cpuid : read_cpuid_id();
+
+		/* read cpu id part number */
+		if ((cpuid & 0xFFF0) == cpu_id)
+			cpumask_set_cpu(cpu, cpumask);
+	}
+
+	drv->cpumask = cpumask;
+

drivers/cpuidle/cpuidle-big_little.c line 147

Quoted 6 lines

drivers/cpuidle/cpuidle-big_little.c new file +6 -0

+	return 0;
+}
+
+static int __init bl_idle_init(void)
+{
+	int ret;

add blank line