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

[Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>]

On Wed, Mar 22, 2017 at 12:31:18AM +0800, fu.wei@linaro.org wrote:
> From: Fu Wei <fu.wei@linaro.org>
> 
> 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@linaro.org>
> Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

Some nits below.

> Tested-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
> Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
> Tested-by: Hanjun Guo <hanjun.guo@linaro.org>
> ---
>  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@linaro.org>
> + *         Fu Wei <fu.wei@linaro.org>
> + *         Hanjun Guo <hanjun.guo@linaro.org>
> + *
> + * 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.

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
>