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

[Lorenzo Pieralisi]

On Wed, Mar 29, 2017 at 10:31:42PM +0800, Fu Wei wrote:
> 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

Ok, to avoid adding bugs to code that has been tested already keep
the current function version (as of v22) and send me a patch to clean
this up at -rc1.

Multiple calls to acpi_gtdt_init() were my main concern.

Thanks,
Lorenzo

> 
> >
> >         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