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Subject[PATCH v4 4/5] arm64: add support for ACPI Low Power Idle(LPI)
Date
This patch adds appropriate callbacks to support ACPI Low Power Idle
(LPI) on ARM64.

It also selects ARCH_SUPPORTS_ACPI_PROCESSOR_LPI if ACPI is enabled
on ARM64.

Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
---
arch/arm64/Kconfig | 1 +
arch/arm64/kernel/acpi.c | 34 ++++++++++++++++++++++++++++++++++
drivers/firmware/psci.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 83 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 4f436220384f..e7536540387d 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -10,6 +10,7 @@ config ARM64
select ARCH_HAS_SG_CHAIN
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
select ARCH_USE_CMPXCHG_LOCKREF
+ select ARCH_SUPPORTS_ACPI_PROCESSOR_LPI if ACPI
select ARCH_SUPPORTS_ATOMIC_RMW
select ARCH_WANT_OPTIONAL_GPIOLIB
select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index d1ce8e2f98b9..3c05ad5957be 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -18,6 +18,7 @@
#include <linux/acpi.h>
#include <linux/bootmem.h>
#include <linux/cpumask.h>
+#include <linux/cpu_pm.h>
#include <linux/init.h>
#include <linux/irq.h>
#include <linux/irqdomain.h>
@@ -25,9 +26,11 @@
#include <linux/of_fdt.h>
#include <linux/smp.h>

+#include <asm/cpuidle.h>
#include <asm/cputype.h>
#include <asm/cpu_ops.h>
#include <asm/smp_plat.h>
+#include <acpi/processor.h>

#ifdef CONFIG_ACPI_APEI
# include <linux/efi.h>
@@ -211,6 +214,37 @@ void __init acpi_boot_table_init(void)
}
}

+int acpi_processor_ffh_lpi_probe(unsigned int cpu)
+{
+ return arm_cpuidle_init(cpu);
+}
+
+struct acpi_processor_lpi *lpi;
+int acpi_processor_ffh_lpi_enter(struct acpi_processor_lpi *lpi, int idx)
+{
+ int ret;
+
+ if (!idx) {
+ cpu_do_idle();
+ return idx;
+ }
+
+ /* TODO cpu_pm_{enter,exit} can be done in generic code ? */
+ ret = cpu_pm_enter();
+ if (!ret) {
+ /*
+ * Pass idle state index to cpu_suspend which in turn will
+ * call the CPU ops suspend protocol with idle index as a
+ * parameter.
+ */
+ ret = arm_cpuidle_suspend(idx);
+
+ cpu_pm_exit();
+ }
+
+ return ret ? -1 : idx;
+}
+
#ifdef CONFIG_ACPI_APEI
pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr)
{
diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
index af6c5c839568..70cf2a500d4b 100644
--- a/drivers/firmware/psci.c
+++ b/drivers/firmware/psci.c
@@ -24,6 +24,7 @@
#include <linux/reboot.h>
#include <linux/slab.h>
#include <linux/suspend.h>
+#include <linux/acpi.h>

#include <uapi/linux/psci.h>

@@ -32,6 +33,7 @@
#include <asm/system_misc.h>
#include <asm/smp_plat.h>
#include <asm/suspend.h>
+#include <acpi/processor.h>

/*
* While a 64-bit OS can make calls with SMC32 calling conventions, for some
@@ -316,8 +318,54 @@ static int psci_dt_cpu_init_idle(unsigned int cpu)
return ret;
}

+static int __maybe_unused psci_acpi_cpu_init_idle(unsigned int cpu)
+{
+ int i, count;
+ u32 *psci_states;
+ struct acpi_processor *pr;
+ struct acpi_processor_lpi *lpi;
+
+ pr = per_cpu(processors, cpu);
+ if (unlikely(!pr || !pr->flags.has_lpi))
+ return -EINVAL;
+
+ /*
+ * If the PSCI cpu_suspend function hook has not been initialized
+ * idle states must not be enabled, so bail out
+ */
+ if (!psci_ops.cpu_suspend)
+ return -EOPNOTSUPP;
+
+ count = pr->power.count - 1;
+ if (!count)
+ return -ENODEV;
+
+ psci_states = kcalloc(count, sizeof(*psci_states), GFP_KERNEL);
+ if (!psci_states)
+ return -ENOMEM;
+
+ for (i = 0; i < count; i++) {
+ u32 state;
+
+ lpi = &pr->power.lpi_states[i + 1];
+ state = lpi->address & 0xFFFFFFFF;
+ if (!psci_power_state_is_valid(state)) {
+ pr_warn("Invalid PSCI power state %#x\n", state);
+ kfree(psci_states);
+ return -EINVAL;
+ }
+ psci_states[i] = state;
+ }
+ /* Idle states parsed correctly, initialize per-cpu pointer */
+ per_cpu(psci_power_state, cpu) = psci_states;
+ return 0;
+}
+
int psci_cpu_init_idle(unsigned int cpu)
{
+ if (!acpi_disabled)
+ return psci_acpi_cpu_init_idle(cpu);
+
return psci_dt_cpu_init_idle(cpu);
}

--
1.9.1
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