[PATCH v4 4/5] arm64: add support for ACPI Low Power Idle(LPI)

[Vikas Sajjan]

Hi Sudeep,

On Tue, Apr 19, 2016 at 6:00 PM, Sudeep Holla <sudeep.holla at arm.com> wrote:
> 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 at arm.com>
> Cc: Mark Rutland <mark.rutland at arm.com>
> Cc: linux-arm-kernel at lists.infradead.org
> Signed-off-by: Sudeep Holla <sudeep.holla at 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);
> +}
> +

This is generating warning as below:

WARNING: vmlinux.o(.text+0x11024): Section mismatch in reference from
the function acpi_processor_ffh_lpi_probe() to the function
.init.text:arm_cpuidle_init()
The function acpi_processor_ffh_lpi_probe() references
the function __init arm_cpuidle_init().
This is often because acpi_processor_ffh_lpi_probe lacks a __init
annotation or the annotation of arm_cpuidle_init is wrong.


> +struct acpi_processor_lpi *lpi;
> +int acpi_processor_ffh_lpi_enter(struct acpi_processor_lpi *lpi, int idx)

Wondering how are you handling with Resource Dependencies for Idle.
I mean _RDI needs to be taken care, since the dependency between the
power resources and the LPI state is described in _RDI.

> +{
> +       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
>