Re: [PATCH v24 09/11] acpi/arm64: Add memory-mapped timer support in GTDT driver

Lorenzo Pieralisi
2017-04-18T17:20:43Z

On Sat, Apr 15, 2017 at 02:40:12AM +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>
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> ---
> drivers/acpi/arm64/gtdt.c | 144 ++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/acpi.h | 1 +
> 2 files changed, 145 insertions(+)
>
> diff --git a/drivers/acpi/arm64/gtdt.c b/drivers/acpi/arm64/gtdt.c
> index 3d95af8..c9ef9c2 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 +178,124 @@ 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);
> + 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->phys_irq > 0)
> + acpi_unregister_irq(frame->phys_irq);
> + if (frame->virt_irq > 0)
> + acpi_unregister_irq(frame->virt_irq);
> + }

There are three error paths, none of them reset [i,gtdt_frame],
correct ?

If yes, why can't it simply be written like this ?

for (; i >= 0; i--, gtdt_frame--) {
frame = &timer_mem->frame[gtdt_frame->frame_number];

/* not sure this check is actually needed */
if (gtdt_frame->common_flags & ACPI_GTDT_GT_IS_SECURE_TIMER)
continue;

if (frame->phys_irq > 0)
acpi_unregister_gsi(gtdt_frame->timer_interrupt);
if (frame->virt_irq > 0)
acpi_unregister_gsi(gtdt_frame->virtual_timer_interrupt);
}

It is time we merged this code, that's for certain so if for any reason
loop above does not work this current series is ok for me, go ahead, I
just don't see the point of adding another ACPI IRQ function
acpi_unregister_irq() (which does not mean acpi_unregister_gsi() is sane
- we just lived with it when ACPI ARM64 was merged because changing its
API requires reworking x86 legacy code that I don't understand).

Thanks,
Lorenzo

> + 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 728d1ed..4b1ab65 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -606,6 +606,7 @@ 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
>