Re: [PATCH v22 07/11] acpi/arm64: Add GTDT table parse driver

From: Fu Wei
Date: Wed Mar 29 2017 - 10:32:23 EST

On 29 March 2017 at 22:29, Fu Wei <fu.wei@xxxxxxxxxx> wrote:
> Hi Lorenzo,
>
> On 28 March 2017 at 19:35, Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx> wrote:
>> On Wed, Mar 22, 2017 at 12:31:18AM +0800, fu.wei@xxxxxxxxxx wrote:
>>> From: Fu Wei <fu.wei@xxxxxxxxxx>
>>>
>>> This patch adds support for parsing arch timer info in GTDT,
>>> provides some kernel APIs to parse all the PPIs and
>>> always-on info in GTDT and export them.
>>>
>>> By this driver, we can simplify arm_arch_timer drivers, and
>>> separate the ACPI GTDT knowledge from it.
>>>
>>> Signed-off-by: Fu Wei <fu.wei@xxxxxxxxxx>
>>> Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
>>> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>>
>> Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
>>
>> Some nits below.
>>
>>> Tested-by: Xiongfeng Wang <wangxiongfeng2@xxxxxxxxxx>
>>> Reviewed-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
>>> Tested-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
>>> ---
>>> arch/arm64/Kconfig | 1 +
>>> drivers/acpi/arm64/Kconfig | 3 +
>>> drivers/acpi/arm64/Makefile | 1 +
>>> drivers/acpi/arm64/gtdt.c | 157 ++++++++++++++++++++++++++++++++++++++++++++
>>> include/linux/acpi.h | 6 ++
>>> 5 files changed, 168 insertions(+)
>>>
>>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
>>> index 3741859..7e2baec 100644
>>> --- a/arch/arm64/Kconfig
>>> +++ b/arch/arm64/Kconfig
>>> @@ -2,6 +2,7 @@ config ARM64
>>> def_bool y
>>> select ACPI_CCA_REQUIRED if ACPI
>>> select ACPI_GENERIC_GSI if ACPI
>>> + select ACPI_GTDT if ACPI
>>> select ACPI_REDUCED_HARDWARE_ONLY if ACPI
>>> select ACPI_MCFG if ACPI
>>> select ACPI_SPCR_TABLE if ACPI
>>> diff --git a/drivers/acpi/arm64/Kconfig b/drivers/acpi/arm64/Kconfig
>>> index 4616da4..5a6f80f 100644
>>> --- a/drivers/acpi/arm64/Kconfig
>>> +++ b/drivers/acpi/arm64/Kconfig
>>> @@ -4,3 +4,6 @@
>>>
>>> config ACPI_IORT
>>> bool
>>> +
>>> +config ACPI_GTDT
>>> + bool
>>> diff --git a/drivers/acpi/arm64/Makefile b/drivers/acpi/arm64/Makefile
>>> index 72331f2..1017def 100644
>>> --- a/drivers/acpi/arm64/Makefile
>>> +++ b/drivers/acpi/arm64/Makefile
>>> @@ -1 +1,2 @@
>>> obj-$(CONFIG_ACPI_IORT) += iort.o
>>> +obj-$(CONFIG_ACPI_GTDT) += gtdt.o
>>> diff --git a/drivers/acpi/arm64/gtdt.c b/drivers/acpi/arm64/gtdt.c
>>> new file mode 100644
>>> index 0000000..8a03b4b
>>> --- /dev/null
>>> +++ b/drivers/acpi/arm64/gtdt.c
>>> @@ -0,0 +1,157 @@
>>> +/*
>>> + * ARM Specific GTDT table Support
>>> + *
>>> + * Copyright (C) 2016, Linaro Ltd.
>>> + * Author: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
>>> + * Fu Wei <fu.wei@xxxxxxxxxx>
>>> + * Hanjun Guo <hanjun.guo@xxxxxxxxxx>
>>> + *
>>> + * 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.
>>> + */
>>> +
>>> +#include <linux/acpi.h>
>>> +#include <linux/init.h>
>>> +#include <linux/kernel.h>
>>> +
>>> +#include <clocksource/arm_arch_timer.h>
>>> +
>>> +#undef pr_fmt
>>> +#define pr_fmt(fmt) "ACPI GTDT: " fmt
>>> +
>>> +/**
>>> + * struct acpi_gtdt_descriptor - Store the key info of GTDT for all functions
>>> + * @gtdt: The pointer to the struct acpi_table_gtdt of GTDT table.
>>> + * @gtdt_end: The pointer to the end of GTDT table.
>>> + * @platform_timer: The pointer to the start of Platform Timer Structure
>>> + *
>>> + * The struct store the key info of GTDT table, it should be initialized by
>>> + * acpi_gtdt_init.
>>> + */
>>> +struct acpi_gtdt_descriptor {
>>> + struct acpi_table_gtdt *gtdt;
>>> + void *gtdt_end;
>>> + void *platform_timer;
>>> +};
>>> +
>>> +static struct acpi_gtdt_descriptor acpi_gtdt_desc __initdata;
>>> +
>>> +static int __init map_gt_gsi(u32 interrupt, u32 flags)
>>> +{
>>> + int trigger, polarity;
>>> +
>>> + trigger = (flags & ACPI_GTDT_INTERRUPT_MODE) ? ACPI_EDGE_SENSITIVE
>>> + : ACPI_LEVEL_SENSITIVE;
>>> +
>>> + polarity = (flags & ACPI_GTDT_INTERRUPT_POLARITY) ? ACPI_ACTIVE_LOW
>>> + : ACPI_ACTIVE_HIGH;
>>> +
>>> + return acpi_register_gsi(NULL, interrupt, trigger, polarity);
>>> +}
>>> +
>>> +/**
>>> + * acpi_gtdt_map_ppi() - Map the PPIs of per-cpu arch_timer.
>>> + * @type: the type of PPI.
>>> + *
>>> + * Note: Linux on arm64 isn't supported on the secure side.
>>
>> Note: Secure state is not managed by the kernel on ARM64 systems.
>>
>> Is that what you wanted to say ?
>>
>>> + * So we only handle the non-secure timer PPIs,
>>> + * ARCH_TIMER_PHYS_SECURE_PPI is treated as invalid type.
>>> + *
>>> + * Return: the mapped PPI value, 0 if error.
>>> + */
>>> +int __init acpi_gtdt_map_ppi(int type)
>>> +{
>>> + struct acpi_table_gtdt *gtdt = acpi_gtdt_desc.gtdt;
>>> +
>>> + switch (type) {
>>> + case ARCH_TIMER_PHYS_NONSECURE_PPI:
>>> + return map_gt_gsi(gtdt->non_secure_el1_interrupt,
>>> + gtdt->non_secure_el1_flags);
>>> + case ARCH_TIMER_VIRT_PPI:
>>> + return map_gt_gsi(gtdt->virtual_timer_interrupt,
>>> + gtdt->virtual_timer_flags);
>>> +
>>> + case ARCH_TIMER_HYP_PPI:
>>> + return map_gt_gsi(gtdt->non_secure_el2_interrupt,
>>> + gtdt->non_secure_el2_flags);
>>> + default:
>>> + pr_err("Failed to map timer interrupt: invalid type.\n");
>>> + }
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +/**
>>> + * acpi_gtdt_c3stop() - Got c3stop info from GTDT according to the type of PPI.
>>> + * @type: the type of PPI.
>>> + *
>>> + * Return: 1 if the timer can be in deep idle state, 0 otherwise.
>>
>> Return: true if the timer HW state is lost when a CPU enters an idle
>> state, false otherwise
>>
>>> + */
>>> +bool __init acpi_gtdt_c3stop(int type)
>>> +{
>>> + struct acpi_table_gtdt *gtdt = acpi_gtdt_desc.gtdt;
>>> +
>>> + switch (type) {
>>> + case ARCH_TIMER_PHYS_NONSECURE_PPI:
>>> + return !(gtdt->non_secure_el1_flags & ACPI_GTDT_ALWAYS_ON);
>>> +
>>> + case ARCH_TIMER_VIRT_PPI:
>>> + return !(gtdt->virtual_timer_flags & ACPI_GTDT_ALWAYS_ON);
>>> +
>>> + case ARCH_TIMER_HYP_PPI:
>>> + return !(gtdt->non_secure_el2_flags & ACPI_GTDT_ALWAYS_ON);
>>> +
>>> + default:
>>> + pr_err("Failed to get c3stop info: invalid type.\n");
>>> + }
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +/**
>>> + * acpi_gtdt_init() - Get the info of GTDT table to prepare for further init.
>>> + * @table: The pointer to GTDT table.
>>> + * @platform_timer_count: The pointer of int variate for returning the
>>
>> I do not understand what this means.
>>
>>> + * number of platform timers. It can be NULL, if
>>> + * driver don't need this info.
>>
>> driver doesn't
>>
>>> + *
>>> + * Return: 0 if success, -EINVAL if error.
>>> + */
>>> +int __init acpi_gtdt_init(struct acpi_table_header *table,
>>> + int *platform_timer_count)
>>> +{
>>> + int ret = 0;
>>> + int timer_count = 0;
>>> + void *platform_timer = NULL;
>>> + struct acpi_table_gtdt *gtdt;
>>> +
>>> + gtdt = container_of(table, struct acpi_table_gtdt, header);
>>> + acpi_gtdt_desc.gtdt = gtdt;
>>> + acpi_gtdt_desc.gtdt_end = (void *)table + table->length;
>>> +
>>> + if (table->revision < 2)
>>> + pr_warn("Revision:%d doesn't support Platform Timers.\n",
>>> + table->revision);
>>
>> Ok, two points here. First, I am not sure why you should warn if the
>> table revision is < 2, is that a FW bug ? I do not think it is, you
>> can just return 0.
>>
>>> + else if (!gtdt->platform_timer_count)
>>> + pr_debug("No Platform Timer.\n");
>>
>> Ditto. Why keep executing ? There is nothing to do, just bail out
>> with a return 0.
>>
>>> + else
>>> + timer_count = gtdt->platform_timer_count;
>>> +
>>> + if (timer_count) {
>>> + platform_timer = (void *)gtdt + gtdt->platform_timer_offset;
>>> + if (platform_timer < (void *)table +
>>> + sizeof(struct acpi_table_gtdt)) {
>>> + pr_err(FW_BUG "invalid timer data.\n");
>>> + timer_count = 0;
>>> + platform_timer = NULL;
>>> + ret = -EINVAL;
>>
>> Same here, I suspect you want to consolidate the return path (I missed
>> previous rounds of reviews so you should not worry too much, I can clean
>> this up later) but to me a:
>>
>> return -EINVAL;
>>
>> would just do.
>
> For this problem, Can I do this:
>
> /**
> * acpi_gtdt_init() - Get the info of GTDT table to prepare for further init.
> * @table: The pointer to GTDT table.
> * @platform_timer_count: It points to a integer variable which is used
> * for storing the number of platform timers.
> * This pointer could be NULL, if the caller
> * doesn't need this info.
> *
> * Return: 0 if success, -EINVAL if error.
> */
> int __init acpi_gtdt_init(struct acpi_table_header *table,
> int *platform_timer_count)
> {
> void *platform_timer;
> struct acpi_table_gtdt *gtdt;
>
> gtdt = container_of(table, struct acpi_table_gtdt, header);
> acpi_gtdt_desc.gtdt = gtdt;
> acpi_gtdt_desc.gtdt_end = (void *)table + table->length;
> acpi_gtdt_desc.platform_timer = NULL;
> if (platform_timer_count)
> *platform_timer_count = 0;
>
> if (table->revision < 2) {
> pr_warn("Revision:%d doesn't support Platform Timers.\n",
> table->revision);
> return 0;
> }
>
> if (!gtdt->platform_timer_count) {
> pr_debug("No Platform Timer.\n");
> return 0;
> }
> if (platform_timer_count)
> *platform_timer_count = gtdt->platform_timer_count;

sorry , this should be moved,


>
> platform_timer = (void *)gtdt + gtdt->platform_timer_offset;
> if (platform_timer < (void *)table + sizeof(struct acpi_table_gtdt)) {
> pr_err(FW_BUG "invalid timer data.\n");
> return -EINVAL;
> }
> acpi_gtdt_desc.platform_timer = platform_timer;

if (platform_timer_count)
*platform_timer_count = gtdt->platform_timer_count;

Here is the right place

>
> return 0;
> }
>
>
>>
>> Lorenzo
>>
>>> + }
>>> + }
>>> +
>>> + acpi_gtdt_desc.platform_timer = platform_timer;
>>> + if (platform_timer_count)
>>> + *platform_timer_count = timer_count;
>>> +
>>> + return ret;
>>> +}
>>> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
>>> index 9b05886..4b5c146 100644
>>> --- a/include/linux/acpi.h
>>> +++ b/include/linux/acpi.h
>>> @@ -595,6 +595,12 @@ enum acpi_reconfig_event {
>>> int acpi_reconfig_notifier_register(struct notifier_block *nb);
>>> int acpi_reconfig_notifier_unregister(struct notifier_block *nb);
>>>
>>> +#ifdef CONFIG_ACPI_GTDT
>>> +int acpi_gtdt_init(struct acpi_table_header *table, int *platform_timer_count);
>>> +int acpi_gtdt_map_ppi(int type);
>>> +bool acpi_gtdt_c3stop(int type);
>>> +#endif
>>> +
>>> #else /* !CONFIG_ACPI */
>>>
>>> #define acpi_disabled 1
>>> --
>>> 2.9.3
>>>
>
>
>
> --
> Best regards,
>
> Fu Wei
> Software Engineer
> Red Hat



--
Best regards,

Fu Wei
Software Engineer
Red Hat