1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * ACPI probing code for ARM performance counters.
  4 *
  5 * Copyright (C) 2017 ARM Ltd.
  6 */
  7
  8#include <linux/acpi.h>
  9#include <linux/cpumask.h>
 10#include <linux/init.h>
 11#include <linux/irq.h>
 12#include <linux/irqdesc.h>
 13#include <linux/percpu.h>
 14#include <linux/perf/arm_pmu.h>
 15
 16#include <asm/cpu.h>
 17#include <asm/cputype.h>
 18
 19static DEFINE_PER_CPU(struct arm_pmu *, probed_pmus);
 20static DEFINE_PER_CPU(int, pmu_irqs);
 21
 22static int arm_pmu_acpi_register_irq(int cpu)
 23{
 24	struct acpi_madt_generic_interrupt *gicc;
 25	int gsi, trigger;
 26
 27	gicc = acpi_cpu_get_madt_gicc(cpu);
 28
 29	gsi = gicc->performance_interrupt;
 30
 31	/*
 32	 * Per the ACPI spec, the MADT cannot describe a PMU that doesn't
 33	 * have an interrupt. QEMU advertises this by using a GSI of zero,
 34	 * which is not known to be valid on any hardware despite being
 35	 * valid per the spec. Take the pragmatic approach and reject a
 36	 * GSI of zero for now.
 37	 */
 38	if (!gsi)
 39		return 0;
 40
 41	if (gicc->flags & ACPI_MADT_PERFORMANCE_IRQ_MODE)
 42		trigger = ACPI_EDGE_SENSITIVE;
 43	else
 44		trigger = ACPI_LEVEL_SENSITIVE;
 45
 46	/*
 47	 * Helpfully, the MADT GICC doesn't have a polarity flag for the
 48	 * "performance interrupt". Luckily, on compliant GICs the polarity is
 49	 * a fixed value in HW (for both SPIs and PPIs) that we cannot change
 50	 * from SW.
 51	 *
 52	 * Here we pass in ACPI_ACTIVE_HIGH to keep the core code happy. This
 53	 * may not match the real polarity, but that should not matter.
 54	 *
 55	 * Other interrupt controllers are not supported with ACPI.
 56	 */
 57	return acpi_register_gsi(NULL, gsi, trigger, ACPI_ACTIVE_HIGH);
 58}
 59
 60static void arm_pmu_acpi_unregister_irq(int cpu)
 61{
 62	struct acpi_madt_generic_interrupt *gicc;
 63	int gsi;
 64
 65	gicc = acpi_cpu_get_madt_gicc(cpu);
 66
 67	gsi = gicc->performance_interrupt;
 68	if (gsi)
 69		acpi_unregister_gsi(gsi);
 70}
 71
 72#if IS_ENABLED(CONFIG_ARM_SPE_PMU)
 73static struct resource spe_resources[] = {
 74	{
 75		/* irq */
 76		.flags          = IORESOURCE_IRQ,
 77	}
 78};
 79
 80static struct platform_device spe_dev = {
 81	.name = ARMV8_SPE_PDEV_NAME,
 82	.id = -1,
 83	.resource = spe_resources,
 84	.num_resources = ARRAY_SIZE(spe_resources)
 85};
 86
 87/*
 88 * For lack of a better place, hook the normal PMU MADT walk
 89 * and create a SPE device if we detect a recent MADT with
 90 * a homogeneous PPI mapping.
 91 */
 92static void arm_spe_acpi_register_device(void)
 93{
 94	int cpu, hetid, irq, ret;
 95	bool first = true;
 96	u16 gsi = 0;
 97
 98	/*
 99	 * Sanity check all the GICC tables for the same interrupt number.
100	 * For now, we only support homogeneous ACPI/SPE machines.
101	 */
102	for_each_possible_cpu(cpu) {
103		struct acpi_madt_generic_interrupt *gicc;
104
105		gicc = acpi_cpu_get_madt_gicc(cpu);
106		if (gicc->header.length < ACPI_MADT_GICC_SPE)
107			return;
108
109		if (first) {
110			gsi = gicc->spe_interrupt;
111			if (!gsi)
112				return;
113			hetid = find_acpi_cpu_topology_hetero_id(cpu);
114			first = false;
115		} else if ((gsi != gicc->spe_interrupt) ||
116			   (hetid != find_acpi_cpu_topology_hetero_id(cpu))) {
117			pr_warn("ACPI: SPE must be homogeneous\n");
118			return;
119		}
120	}
121
122	irq = acpi_register_gsi(NULL, gsi, ACPI_LEVEL_SENSITIVE,
123				ACPI_ACTIVE_HIGH);
124	if (irq < 0) {
125		pr_warn("ACPI: SPE Unable to register interrupt: %d\n", gsi);
126		return;
127	}
128
129	spe_resources[0].start = irq;
130	ret = platform_device_register(&spe_dev);
131	if (ret < 0) {
132		pr_warn("ACPI: SPE: Unable to register device\n");
133		acpi_unregister_gsi(gsi);
134	}
135}
136#else
137static inline void arm_spe_acpi_register_device(void)
138{
139}
140#endif /* CONFIG_ARM_SPE_PMU */
141
142static int arm_pmu_acpi_parse_irqs(void)
143{
144	int irq, cpu, irq_cpu, err;
145
146	for_each_possible_cpu(cpu) {
147		irq = arm_pmu_acpi_register_irq(cpu);
148		if (irq < 0) {
149			err = irq;
150			pr_warn("Unable to parse ACPI PMU IRQ for CPU%d: %d\n",
151				cpu, err);
152			goto out_err;
153		} else if (irq == 0) {
154			pr_warn("No ACPI PMU IRQ for CPU%d\n", cpu);
155		}
156
157		/*
158		 * Log and request the IRQ so the core arm_pmu code can manage
159		 * it. We'll have to sanity-check IRQs later when we associate
160		 * them with their PMUs.
161		 */
162		per_cpu(pmu_irqs, cpu) = irq;
163		err = armpmu_request_irq(irq, cpu);
164		if (err)
165			goto out_err;
166	}
167
168	return 0;
169
170out_err:
171	for_each_possible_cpu(cpu) {
172		irq = per_cpu(pmu_irqs, cpu);
173		if (!irq)
174			continue;
175
176		arm_pmu_acpi_unregister_irq(cpu);
177
178		/*
179		 * Blat all copies of the IRQ so that we only unregister the
180		 * corresponding GSI once (e.g. when we have PPIs).
181		 */
182		for_each_possible_cpu(irq_cpu) {
183			if (per_cpu(pmu_irqs, irq_cpu) == irq)
184				per_cpu(pmu_irqs, irq_cpu) = 0;
185		}
186	}
187
188	return err;
189}
190
191static struct arm_pmu *arm_pmu_acpi_find_pmu(void)
192{
193	unsigned long cpuid = read_cpuid_id();
194	struct arm_pmu *pmu;
195	int cpu;
196
197	for_each_possible_cpu(cpu) {
198		pmu = per_cpu(probed_pmus, cpu);
199		if (!pmu || pmu->acpi_cpuid != cpuid)
200			continue;
201
202		return pmu;
203	}
204
205	return NULL;
206}
207
208/*
209 * Check whether the new IRQ is compatible with those already associated with
210 * the PMU (e.g. we don't have mismatched PPIs).
211 */
212static bool pmu_irq_matches(struct arm_pmu *pmu, int irq)
213{
214	struct pmu_hw_events __percpu *hw_events = pmu->hw_events;
215	int cpu;
216
217	if (!irq)
218		return true;
219
220	for_each_cpu(cpu, &pmu->supported_cpus) {
221		int other_irq = per_cpu(hw_events->irq, cpu);
222		if (!other_irq)
223			continue;
224
225		if (irq == other_irq)
226			continue;
227		if (!irq_is_percpu_devid(irq) && !irq_is_percpu_devid(other_irq))
228			continue;
229
230		pr_warn("mismatched PPIs detected\n");
231		return false;
232	}
233
234	return true;
235}
236
237static void arm_pmu_acpi_associate_pmu_cpu(struct arm_pmu *pmu,
238					   unsigned int cpu)
239{
240	int irq = per_cpu(pmu_irqs, cpu);
241
242	per_cpu(probed_pmus, cpu) = pmu;
243
244	if (pmu_irq_matches(pmu, irq)) {
245		struct pmu_hw_events __percpu *hw_events;
246		hw_events = pmu->hw_events;
247		per_cpu(hw_events->irq, cpu) = irq;
248	}
249
250	cpumask_set_cpu(cpu, &pmu->supported_cpus);
251}
252
253/*
254 * This must run before the common arm_pmu hotplug logic, so that we can
255 * associate a CPU and its interrupt before the common code tries to manage the
256 * affinity and so on.
257 *
258 * Note that hotplug events are serialized, so we cannot race with another CPU
259 * coming up. The perf core won't open events while a hotplug event is in
260 * progress.
261 */
262static int arm_pmu_acpi_cpu_starting(unsigned int cpu)
263{
264	struct arm_pmu *pmu;
265
266	/* If we've already probed this CPU, we have nothing to do */
267	if (per_cpu(probed_pmus, cpu))
268		return 0;
269
270	pmu = arm_pmu_acpi_find_pmu();
271	if (!pmu) {
272		pr_warn_ratelimited("Unable to associate CPU%d with a PMU\n",
273				    cpu);
274		return 0;
275	}
276
277	arm_pmu_acpi_associate_pmu_cpu(pmu, cpu);
278	return 0;
279}
280
281static void arm_pmu_acpi_probe_matching_cpus(struct arm_pmu *pmu,
282					     unsigned long cpuid)
283{
284	int cpu;
285
286	for_each_online_cpu(cpu) {
287		unsigned long cpu_cpuid = per_cpu(cpu_data, cpu).reg_midr;
288
289		if (cpu_cpuid == cpuid)
290			arm_pmu_acpi_associate_pmu_cpu(pmu, cpu);
291	}
292}
293
294int arm_pmu_acpi_probe(armpmu_init_fn init_fn)
295{
296	int pmu_idx = 0;
297	unsigned int cpu;
298	int ret;
299
300	ret = arm_pmu_acpi_parse_irqs();
301	if (ret)
302		return ret;
303
304	ret = cpuhp_setup_state_nocalls(CPUHP_AP_PERF_ARM_ACPI_STARTING,
305					"perf/arm/pmu_acpi:starting",
306					arm_pmu_acpi_cpu_starting, NULL);
307	if (ret)
308		return ret;
309
310	/*
311	 * Initialise and register the set of PMUs which we know about right
312	 * now. Ideally we'd do this in arm_pmu_acpi_cpu_starting() so that we
313	 * could handle late hotplug, but this may lead to deadlock since we
314	 * might try to register a hotplug notifier instance from within a
315	 * hotplug notifier.
316	 *
317	 * There's also the problem of having access to the right init_fn,
318	 * without tying this too deeply into the "real" PMU driver.
319	 *
320	 * For the moment, as with the platform/DT case, we need at least one
321	 * of a PMU's CPUs to be online at probe time.
322	 */
323	for_each_online_cpu(cpu) {
324		struct arm_pmu *pmu = per_cpu(probed_pmus, cpu);
325		unsigned long cpuid;
326		char *base_name;
327
328		/* If we've already probed this CPU, we have nothing to do */
329		if (pmu)
330			continue;
331
332		pmu = armpmu_alloc();
333		if (!pmu) {
334			pr_warn("Unable to allocate PMU for CPU%d\n",
335				cpu);
336			return -ENOMEM;
337		}
338
339		cpuid = per_cpu(cpu_data, cpu).reg_midr;
340		pmu->acpi_cpuid = cpuid;
341
342		arm_pmu_acpi_probe_matching_cpus(pmu, cpuid);
343
344		ret = init_fn(pmu);
345		if (ret == -ENODEV) {
346			/* PMU not handled by this driver, or not present */
347			continue;
348		} else if (ret) {
349			pr_warn("Unable to initialise PMU for CPU%d\n", cpu);
350			return ret;
351		}
352
353		base_name = pmu->name;
354		pmu->name = kasprintf(GFP_KERNEL, "%s_%d", base_name, pmu_idx++);
355		if (!pmu->name) {
356			pr_warn("Unable to allocate PMU name for CPU%d\n", cpu);
357			return -ENOMEM;
358		}
359
360		ret = armpmu_register(pmu);
361		if (ret) {
362			pr_warn("Failed to register PMU for CPU%d\n", cpu);
363			kfree(pmu->name);
364			return ret;
365		}
366	}
367
368	return ret;
369}
370
371static int arm_pmu_acpi_init(void)
372{
373	if (acpi_disabled)
374		return 0;
375
376	arm_spe_acpi_register_device();
377
378	return 0;
379}
380subsys_initcall(arm_pmu_acpi_init)