drivers/platform/x86/intel/turbo_max_3.c

Source file repositories/reference/linux-study-clean/drivers/platform/x86/intel/turbo_max_3.c

File Facts

System
Linux kernel
Corpus path
drivers/platform/x86/intel/turbo_max_3.c
Extension
.c
Size
3543 bytes
Lines
141
Domain
Driver Families
Bucket
drivers/platform
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

if (ret) {
			pr_debug("cpu %d OC mailbox read failed\n", cpu);
			break;
		}

		if (value & BIT_ULL(MSR_OC_MAILBOX_BUSY_BIT)) {
			pr_debug("cpu %d OC mailbox still processing\n", cpu);
			ret = -EBUSY;
			continue;
		}

		if ((value >> MSR_OC_MAILBOX_RSP_OFFSET) & 0xff) {
			pr_debug("cpu %d OC mailbox cmd failed\n", cpu);
			ret = -ENXIO;
			break;
		}

		ret = value & 0xff;
		pr_debug("cpu %d max_ratio %d\n", cpu, ret);
		break;
	}

	return ret;
}

/*
 * The work item is needed to avoid CPU hotplug locking issues. The function
 * itmt_legacy_set_priority() is called from CPU online callback, so can't
 * call sched_set_itmt_support() from there as this function will aquire
 * hotplug locks in its path.
 */
static void itmt_legacy_work_fn(struct work_struct *work)
{
	sched_set_itmt_support();
}

static DECLARE_WORK(sched_itmt_work, itmt_legacy_work_fn);

static int itmt_legacy_cpu_online(unsigned int cpu)
{
	static u32 max_highest_perf = 0, min_highest_perf = U32_MAX;
	int priority;

	priority = get_oc_core_priority(cpu);
	if (priority < 0)
		return 0;

	sched_set_itmt_core_prio(priority, cpu);

	/* Enable ITMT feature when a core with different priority is found */
	if (max_highest_perf <= min_highest_perf) {
		if (priority > max_highest_perf)
			max_highest_perf = priority;

		if (priority < min_highest_perf)
			min_highest_perf = priority;

		if (max_highest_perf > min_highest_perf)
			schedule_work(&sched_itmt_work);
	}

	return 0;
}

static const struct x86_cpu_id itmt_legacy_cpu_ids[] = {
	X86_MATCH_VFM(INTEL_BROADWELL_X,	NULL),
	X86_MATCH_VFM(INTEL_SKYLAKE_X,	NULL),
	{}
};

static int __init itmt_legacy_init(void)
{
	const struct x86_cpu_id *id;
	int ret;

	id = x86_match_cpu(itmt_legacy_cpu_ids);
	if (!id)
		return -ENODEV;

	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
				"platform/x86/turbo_max_3:online",
				itmt_legacy_cpu_online,	NULL);
	if (ret < 0)
		return ret;

	return 0;
}
late_initcall(itmt_legacy_init)

Annotation

Implementation Notes