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SubjectRe: [PATCH v23 09/11] acpi/arm64: Add memory-mapped timer support in GTDT driver
Hi Lorenzo,

On 3 April 2017 at 18:45, Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> wrote:
> On Sat, Apr 01, 2017 at 01:51:03AM +0800, fu.wei@linaro.org wrote:
>> From: Fu Wei <fu.wei@linaro.org>
>>
>> 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@linaro.org>
>> Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
>> ---
>> drivers/acpi/arm64/gtdt.c | 146 ++++++++++++++++++++++++++++++++++++++++++++++
>> include/linux/acpi.h | 1 +
>> 2 files changed, 147 insertions(+)
>>
>> diff --git a/drivers/acpi/arm64/gtdt.c b/drivers/acpi/arm64/gtdt.c
>> index 3d95af8..3dd33f3 100644
>> --- a/drivers/acpi/arm64/gtdt.c
>> +++ b/drivers/acpi/arm64/gtdt.c
>> @@ -13,6 +13,7 @@
>>
>> #include <linux/acpi.h>
>> #include <linux/init.h>
>> +#include <linux/irqdomain.h>
>> #include <linux/kernel.h>
>>
>> #include <clocksource/arm_arch_timer.h>
>> @@ -37,6 +38,28 @@ 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 +178,126 @@ int __init acpi_gtdt_init(struct acpi_table_header *table,
>>
>> return 0;
>> }
>> +
>> +static int __init gtdt_parse_timer_block(struct acpi_gtdt_timer_block *block,
>> + struct arch_timer_mem *timer_mem)
>> +{
>> + int i;
>> + struct arch_timer_mem_frame *frame;
>> + 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; i < block->timer_count; i++, gtdt_frame++) {
>> + if (gtdt_frame->common_flags & ACPI_GTDT_GT_IS_SECURE_TIMER)
>> + continue;
>> +
>> + if (!gtdt_frame->base_address || !gtdt_frame->timer_interrupt)
>> + goto error;
>> +
>> + frame = &timer_mem->frame[gtdt_frame->frame_number];
>> + 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",
>> + gtdt_frame->frame_number);
>> + goto error;
>> + }
>> +
>> + if (gtdt_frame->virtual_timer_interrupt) {
>> + 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",
>> + gtdt_frame->frame_number);
>> + acpi_unregister_gsi(gtdt_frame->timer_interrupt);
>> + goto error;
>> + }
>> + } else {
>> + frame->virt_irq = 0;
>> + pr_debug("virtual timer in frame %d not implemented.\n",
>> + 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;
>> + frame->valid = true;
>> + }
>> +
>> + return 0;
>> +
>> +error:
>> + for (i = 0; i < ARCH_TIMER_MEM_MAX_FRAMES; i++) {
>> + frame = &timer_mem->frame[i];
>> + if (!frame->valid)
>> + continue;
>> + irq_dispose_mapping(frame->phys_irq);
>> + if (frame->virt_irq)
>> + irq_dispose_mapping(frame->virt_irq);
>> + }
>
> You should unregister GSIs with the same API you use to register GSIs,
> I do not like code that assumes acpi_unregister_gsi() internal
> implementation, it is wrong to do that.

Thanks for pointing it out, I have thought about it.
But the the same API I use to register GSIs is acpi_unregister_gsi(GSI);
that means we need GSI as the parameter. But when the register goes
wrong, and goto error, the info we have is the IRQ but not GSI. So I
use the acpi_unregister_gsi() internal implementation.
If we try to use the same API, we may need to add this info into
struct arch_timer_mem_frame only for unwinding.

But yes, we do have another way to do, that is registering GSI untill
we figure out which is the "best_frame". But this requires some bigger
change(like using the irq_of_parse_and_map() internal implementation
to get GSI but don't map), and map GSI untill get the "best_frame" .

which way do you prefer?

But I will unify the API in v24

>
> Other than that patch is ok:
>
> Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
>
>> + return -EINVAL;
>> +}
>> +
>> +/**
>> + * 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).
>> + * @timer_count: It points to a integer variable which is used for storing the
>> + * number of GT blocks we have parsed.
>> + *
>> + * 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;
>> + 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
>>



--
Best regards,

Fu Wei
Software Engineer
Red Hat

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