Re: [PATCH v22 09/11] acpi/arm64: Add memory-mapped timer support in GTDT driver

[Lorenzo Pieralisi]

On Wed, Mar 22, 2017 at 12:31:20AM +0800, fu.wei@xxxxxxxxxx wrote:
> From: Fu Wei <fu.wei@xxxxxxxxxx>
> 
> On platforms booting with ACPI, architected memory-mapped timers'
> configuration data is provided by firmware through the ACPI GTDT
> static table.
> 
> The clocksource architected timer kernel driver requires a firmware
> interface to collect timer configuration and configure its driver.
> this infrastructure is present for device tree systems, but it is
> missing on systems booting with ACPI.
> 
> Implement the kernel infrastructure required to parse the static
> ACPI GTDT table so that the architected timer clocksource driver can
> make use of it on systems booting with ACPI, therefore enabling
> the corresponding timers configuration.
> 
> Signed-off-by: Fu Wei <fu.wei@xxxxxxxxxx>
> Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
> ---
>  drivers/acpi/arm64/gtdt.c | 130 ++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/acpi.h      |   1 +
>  2 files changed, 131 insertions(+)
> 
> diff --git a/drivers/acpi/arm64/gtdt.c b/drivers/acpi/arm64/gtdt.c
> index 8a03b4b..f471873 100644
> --- a/drivers/acpi/arm64/gtdt.c
> +++ b/drivers/acpi/arm64/gtdt.c
> @@ -37,6 +37,28 @@ struct acpi_gtdt_descriptor {
>  
>  static struct acpi_gtdt_descriptor acpi_gtdt_desc __initdata;
>  
> +static inline void *next_platform_timer(void *platform_timer)
> +{
> +	struct acpi_gtdt_header *gh = platform_timer;
> +
> +	platform_timer += gh->length;
> +	if (platform_timer < acpi_gtdt_desc.gtdt_end)
> +		return platform_timer;
> +
> +	return NULL;
> +}
> +
> +#define for_each_platform_timer(_g)				\
> +	for (_g = acpi_gtdt_desc.platform_timer; _g;	\
> +	     _g = next_platform_timer(_g))
> +
> +static inline bool is_timer_block(void *platform_timer)
> +{
> +	struct acpi_gtdt_header *gh = platform_timer;
> +
> +	return gh->type == ACPI_GTDT_TYPE_TIMER_BLOCK;
> +}
> +
>  static int __init map_gt_gsi(u32 interrupt, u32 flags)
>  {
>  	int trigger, polarity;
> @@ -155,3 +177,111 @@ int __init acpi_gtdt_init(struct acpi_table_header *table,
>  
>  	return ret;
>  }
> +
> +static int __init gtdt_parse_timer_block(struct acpi_gtdt_timer_block *block,
> +					 struct arch_timer_mem *timer_mem)
> +{
> +	int i, j;
> +	struct acpi_gtdt_timer_entry *gtdt_frame;
> +
> +	if (!block->timer_count) {
> +		pr_err(FW_BUG "GT block present, but frame count is zero.");
> +		return -ENODEV;
> +	}
> +
> +	if (block->timer_count > ARCH_TIMER_MEM_MAX_FRAMES) {
> +		pr_err(FW_BUG "GT block lists %d frames, ACPI spec only allows 8\n",
> +		       block->timer_count);
> +		return -EINVAL;
> +	}
> +
> +	timer_mem->cntctlbase = (phys_addr_t)block->block_address;
> +	/*
> +	 * The CNTCTLBase frame is 4KB (register offsets 0x000 - 0xFFC).
> +	 * See ARM DDI 0487A.k_iss10775, page I1-5129, Table I1-3
> +	 * "CNTCTLBase memory map".
> +	 */
> +	timer_mem->size = SZ_4K;
> +
> +	gtdt_frame = (void *)block + block->timer_offset;
> +	if (gtdt_frame + block->timer_count != (void *)block + block->header.length)
> +		return -EINVAL;
> +
> +	/*
> +	 * Get the GT timer Frame data for every GT Block Timer
> +	 */
> +	for (i = 0, j = 0; i < block->timer_count; i++, gtdt_frame++) {
> +		struct arch_timer_mem_frame *frame = &timer_mem->frame[j];
> +
> +		if (gtdt_frame->common_flags & ACPI_GTDT_GT_IS_SECURE_TIMER)
> +			continue;
> +
> +		if (!gtdt_frame->base_address || !gtdt_frame->timer_interrupt)
> +			return -EINVAL;
> +
> +		frame->phys_irq = map_gt_gsi(gtdt_frame->timer_interrupt,
> +					     gtdt_frame->timer_flags);
> +		if (frame->phys_irq <= 0) {
> +			pr_warn("failed to map physical timer irq in frame %d.\n",
> +				i);
> +			return -EINVAL;
> +		}
> +
> +		frame->virt_irq =
> +			map_gt_gsi(gtdt_frame->virtual_timer_interrupt,
> +				   gtdt_frame->virtual_timer_flags);
> +		if (frame->virt_irq <= 0) {
> +			pr_warn("failed to map virtual timer irq in frame %d.\n",
> +				i);
> +			acpi_unregister_gsi(gtdt_frame->timer_interrupt);
> +			return -EINVAL;
> +		}
> +
> +		frame->frame_nr = gtdt_frame->frame_number;
> +		frame->cntbase = gtdt_frame->base_address;
> +		/*
> +		 * The CNTBaseN frame is 4KB (register offsets 0x000 - 0xFFC).
> +		 * See ARM DDI 0487A.k_iss10775, page I1-5130, Table I1-4
> +		 * "CNTBaseN memory map".
> +		 */
> +		frame->size = SZ_4K;
> +		j++;
> +	}
> +	timer_mem->num_frames = j;
> +
> +	return 0;
> +}
> +
> +/**
> + * acpi_arch_timer_mem_init() - Get the info of all GT blocks in GTDT table.
> + * @timer_mem:	the pointer to the array of struct arch_timer_mem for returning
> + *		the result of parsing. The element number of this array should
> + *		be platform_timer_count(the total number of platform timers).
> + * @count:	The pointer of int variate for returning the number of GT
> + *		blocks we have parsed.

Nit: this comment was wrong on all the patches I reviewed :) must be
some copy and paste.

> + *
> + * Return: 0 if success, -EINVAL/-ENODEV if error.
> + */
> +int __init acpi_arch_timer_mem_init(struct arch_timer_mem *timer_mem,
> +				    int *timer_count)
> +{
> +	int ret;
> +	void *platform_timer;
> +
> +	*timer_count = 0;
> +	for_each_platform_timer(platform_timer) {
> +		if (is_timer_block(platform_timer)) {
> +			ret = gtdt_parse_timer_block(platform_timer, timer_mem);
> +			if (ret)
> +				return ret;

Isn't there some unwinding to carry out here (eg GSI) ?

Otherwise it looks fine (minus Mark's request for using frame numbers
as indexes that you should change).

Lorenzo

> +			timer_mem++;
> +			(*timer_count)++;
> +		}
> +	}
> +
> +	if (*timer_count)
> +		pr_info("found %d memory-mapped timer block(s).\n",
> +			*timer_count);
> +
> +	return 0;
> +}
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 4b5c146..3193724 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -599,6 +599,7 @@ int acpi_reconfig_notifier_unregister(struct notifier_block *nb);
>  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);
> +int acpi_arch_timer_mem_init(struct arch_timer_mem *timer_mem, int *timer_count);
>  #endif
>  
>  #else	/* !CONFIG_ACPI */
> -- 
> 2.9.3
>