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

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Message-ID: <20160420183958.648980db@xhacker>
Date:	Wed, 20 Apr 2016 18:39:58 +0800
From:	Jisheng Zhang <jszhang@...vell.com>
To:	Sudeep Holla <sudeep.holla@....com>
CC:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	<linux-acpi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	Mark Rutland <mark.rutland@....com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Al Stone <al.stone@...aro.org>,
	"Prashanth Prakash" <pprakash@...eaurora.org>,
	Ashwin Chaugule <ashwin.chaugule@...aro.org>
Subject: Re: [PATCH v4 4/5] arm64: add support for ACPI Low Power Idle(LPI)

Dear Sudeep,

On Tue, 19 Apr 2016 13:30:12 +0100 Sudeep Holla 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@....com>
> Cc: Mark Rutland <mark.rutland@....com>
> Cc: linux-arm-kernel@...ts.infradead.org
> Signed-off-by: Sudeep Holla <sudeep.holla@....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>

It's better to keep headers alphabetic sorted

>  
>  #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>

same here

>  
>  #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>

ditto

>  
>  /*
>   * 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);
>  }
>