Re: [PATCH v5 2/2] ThunderX2: Add Cavium ThunderX2 SoC UNCORE PMU driver

From: John Garry
Date: Thu May 17 2018 - 06:15:47 EST

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On 16/05/2018 05:55, Ganapatrao Kulkarni wrote:

This patch adds a perf driver for the PMU UNCORE devices DDR4 Memory
Controller(DMC) and Level 3 Cache(L3C).

Hi,

Just some coding comments below:

ThunderX2 has 8 independent DMC PMUs to capture performance events
corresponding to 8 channels of DDR4 Memory Controller and 16 independent
L3C PMUs to capture events corresponding to 16 tiles of L3 cache.
Each PMU supports up to 4 counters. All counters lack overflow interrupt
and are sampled periodically.

Signed-off-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@xxxxxxxxxx>
---
drivers/perf/Kconfig | 8 +
drivers/perf/Makefile | 1 +
drivers/perf/thunderx2_pmu.c | 965 +++++++++++++++++++++++++++++++++++++++++++
include/linux/cpuhotplug.h | 1 +
4 files changed, 975 insertions(+)
create mode 100644 drivers/perf/thunderx2_pmu.c

diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
index 28bb5a0..eafd0fc 100644
--- a/drivers/perf/Kconfig
+++ b/drivers/perf/Kconfig
@@ -85,6 +85,14 @@ config QCOM_L3_PMU
Adds the L3 cache PMU into the perf events subsystem for
monitoring L3 cache events.

+config THUNDERX2_PMU
+ bool "Cavium ThunderX2 SoC PMU UNCORE"
+ depends on ARCH_THUNDER2 && PERF_EVENTS && ACPI

Is the explicit dependency for PERF_EVENTS required, since we're under the PERF_EVENTS menu?

And IIRC for other perf drivers we required a dependency on ARM64 - is that required here also? I see arm_smccc_smc() calls in the code...

+ help
+ Provides support for ThunderX2 UNCORE events.
+ The SoC has PMU support in its L3 cache controller (L3C) and
+ in the DDR4 Memory Controller (DMC).
+
config XGENE_PMU
depends on ARCH_XGENE
bool "APM X-Gene SoC PMU"
diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
index b3902bd..909f27f 100644
--- a/drivers/perf/Makefile
+++ b/drivers/perf/Makefile
@@ -7,5 +7,6 @@ obj-$(CONFIG_ARM_PMU_ACPI) += arm_pmu_acpi.o
obj-$(CONFIG_HISI_PMU) += hisilicon/
obj-$(CONFIG_QCOM_L2_PMU) += qcom_l2_pmu.o
obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o
+obj-$(CONFIG_THUNDERX2_PMU) += thunderx2_pmu.o
obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o
obj-$(CONFIG_ARM_SPE_PMU) += arm_spe_pmu.o
diff --git a/drivers/perf/thunderx2_pmu.c b/drivers/perf/thunderx2_pmu.c
new file mode 100644
index 0000000..0401443
--- /dev/null
+++ b/drivers/perf/thunderx2_pmu.c
@@ -0,0 +1,965 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * CAVIUM THUNDERX2 SoC PMU UNCORE
+ *
+ * Copyright (C) 2018 Cavium Inc.
+ * Author: Ganapatrao Kulkarni <gkulkarni@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */

Isn't this the same as the SPDX?

+
+#include <linux/acpi.h>
+#include <linux/arm-smccc.h>
+#include <linux/cpuhotplug.h>
+#include <linux/perf_event.h>
+#include <linux/platform_device.h>
+
+/* L3c and DMC has 16 and 8 channels per socket respectively.

L3C, right?

+ * Each Channel supports UNCORE PMU device and consists of
+ * 4 independent programmable counters. Counters are 32 bit
+ * and does not support overflow interrupt, they needs to be

/s/needs/need/, /s/does/do/

+ * sampled before overflow(i.e, at every 2 seconds).

how can you ensure that this value is low enough?

"I saw this comment in previous patch:
> Given that all channels compete for access to the muxed register
> interface, I suspect we need to try more often than once every 2
> seconds...

2 seconds seems to be sufficient. So far testing looks good."

Can you provide any more analytical reasoning than this?

+ */
+
+#define UNCORE_MAX_COUNTERS 4
+#define UNCORE_L3_MAX_TILES 16
+#define UNCORE_DMC_MAX_CHANNELS 8
+
+#define UNCORE_HRTIMER_INTERVAL (2 * NSEC_PER_SEC)
+#define GET_EVENTID(ev) ((ev->hw.config) & 0x1ff)
+#define GET_COUNTERID(ev) ((ev->hw.idx) & 0xf)
+#define GET_CHANNELID(pmu_uncore) (pmu_uncore->channel)
+#define DMC_EVENT_CFG(idx, val) ((val) << (((idx) * 8) + 1))
+
+#define DMC_COUNTER_CTL 0x234
+#define DMC_COUNTER_DATA 0x240
+#define L3C_COUNTER_CTL 0xA8
+#define L3C_COUNTER_DATA 0xAC

I feel it's generally better to keep register offsets in numeric order (if indeed, that is what they are)

+
+#define THUNDERX2_SMC_CALL_ID 0xC200FF00
+#define THUNDERX2_SMC_SET_CHANNEL 0xB010
+
+enum thunderx2_uncore_l3_events {
+ L3_EVENT_NONE,
+ L3_EVENT_NBU_CANCEL,
+ L3_EVENT_DIB_RETRY,
+ L3_EVENT_DOB_RETRY,
+ L3_EVENT_DIB_CREDIT_RETRY,
+ L3_EVENT_DOB_CREDIT_RETRY,
+ L3_EVENT_FORCE_RETRY,
+ L3_EVENT_IDX_CONFLICT_RETRY,
+ L3_EVENT_EVICT_CONFLICT_RETRY,
+ L3_EVENT_BANK_CONFLICT_RETRY,
+ L3_EVENT_FILL_ENTRY_RETRY,
+ L3_EVENT_EVICT_NOT_READY_RETRY,
+ L3_EVENT_L3_RETRY,
+ L3_EVENT_READ_REQ,
+ L3_EVENT_WRITE_BACK_REQ,
+ L3_EVENT_INVALIDATE_NWRITE_REQ,
+ L3_EVENT_INV_REQ,
+ L3_EVENT_SELF_REQ,
+ L3_EVENT_REQ,
+ L3_EVENT_EVICT_REQ,
+ L3_EVENT_INVALIDATE_NWRITE_HIT,
+ L3_EVENT_INVALIDATE_HIT,
+ L3_EVENT_SELF_HIT,
+ L3_EVENT_READ_HIT,
+ L3_EVENT_MAX,

',' required?

+};
+
+enum thunderx2_uncore_dmc_events {
+ DMC_EVENT_NONE,
+ DMC_EVENT_COUNT_CYCLES,
+ DMC_EVENT_RES2,
+ DMC_EVENT_RES3,
+ DMC_EVENT_RES4,
+ DMC_EVENT_RES5,
+ DMC_EVENT_RES6,
+ DMC_EVENT_RES7,
+ DMC_EVENT_RES8,
+ DMC_EVENT_READ_64B_TXNS,
+ DMC_EVENT_READ_BELOW_64B_TXNS,
+ DMC_EVENT_WRITE_TXNS,
+ DMC_EVENT_TXN_CYCLES,
+ DMC_EVENT_DATA_TRANSFERS,
+ DMC_EVENT_CANCELLED_READ_TXNS,
+ DMC_EVENT_CONSUMED_READ_TXNS,
+ DMC_EVENT_MAX,

ditto

+};
+
+enum thunderx2_uncore_type {
+ PMU_TYPE_L3C,
+ PMU_TYPE_DMC,
+ PMU_TYPE_INVALID,
+};
+
+/*
+ * pmu on each socket has 2 uncore devices(dmc and l3),
+ * each uncore device has up to 16 channels, each channel can sample
+ * events independently with counters up to 4.
+ *
+ * struct thunderx2_pmu_uncore_channel created per channel.
+ * struct thunderx2_pmu_uncore_dev per uncore device.

this comment is a bit obvious

+ */
+struct thunderx2_pmu_uncore_channel {
+ struct pmu pmu;
+ struct hlist_node node;
+ struct thunderx2_pmu_uncore_dev *uncore_dev;
+ int channel;
+ int cpu;
+ DECLARE_BITMAP(active_counters, UNCORE_MAX_COUNTERS);
+ struct perf_event *events[UNCORE_MAX_COUNTERS];
+ struct hrtimer hrtimer;
+ /* to sync counter alloc/release */
+ raw_spinlock_t lock;
+};
+
+struct thunderx2_pmu_uncore_dev {
+ char *name;
+ struct device *dev;
+ enum thunderx2_uncore_type type;
+ void __iomem *base;
+ int node;
+ u32 max_counters;
+ u32 max_channels;
+ u32 max_events;
+ u64 hrtimer_interval;
+ /* this lock synchronizes across channels */
+ raw_spinlock_t lock;
+ const struct attribute_group **attr_groups;
+ void (*init_cntr_base)(struct perf_event *event,
+ struct thunderx2_pmu_uncore_dev *uncore_dev);
+ void (*select_channel)(struct perf_event *event);
+ void (*stop_event)(struct perf_event *event);
+ void (*start_event)(struct perf_event *event, int flags);
+};
+
+static inline struct thunderx2_pmu_uncore_channel *

is inline keyword required or even used generally? Since static, can't the compiler figure this out?

+pmu_to_thunderx2_pmu_uncore(struct pmu *pmu)
+{
+ return container_of(pmu, struct thunderx2_pmu_uncore_channel, pmu);
+}
+
+/*
+ * sysfs format attributes
+ */

can't this comment fit on a single line?

+static ssize_t thunderx2_pmu_format_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct dev_ext_attribute *eattr;
+
+ eattr = container_of(attr, struct dev_ext_attribute, attr);
+ return sprintf(buf, "%s\n", (char *) eattr->var);
+}
+
+#define FORMAT_ATTR(_name, _config) \
+ (&((struct dev_ext_attribute[]) { \
+ { \
+ .attr = __ATTR(_name, 0444, thunderx2_pmu_format_show, NULL), \
+ .var = (void *) _config, \
+ } \
+ })[0].attr.attr)
+
+static struct attribute *l3c_pmu_format_attrs[] = {
+ FORMAT_ATTR(event, "config:0-4"),
+ NULL,
+};
+
+static struct attribute *dmc_pmu_format_attrs[] = {
+ FORMAT_ATTR(event, "config:0-4"),
+ NULL,
+};
+
+static const struct attribute_group l3c_pmu_format_attr_group = {
+ .name = "format",
+ .attrs = l3c_pmu_format_attrs,
+};
+
+static const struct attribute_group dmc_pmu_format_attr_group = {
+ .name = "format",
+ .attrs = dmc_pmu_format_attrs,
+};
+

[ ... ]

+ * Per PMU device attribute groups
+ */
+static const struct attribute_group *l3c_pmu_attr_groups[] = {
+ &l3c_pmu_format_attr_group,
+ &pmu_cpumask_attr_group,
+ &l3c_pmu_events_attr_group,
+ NULL
+};
+
+static const struct attribute_group *dmc_pmu_attr_groups[] = {
+ &dmc_pmu_format_attr_group,
+ &pmu_cpumask_attr_group,
+ &dmc_pmu_events_attr_group,
+ NULL
+};
+
+static inline u32 reg_readl(unsigned long addr)
+{
+ return readl((void __iomem *)addr);
+}
+
+static inline void reg_writel(u32 val, unsigned long addr)
+{
+ writel(val, (void __iomem *)addr);
+}
+
+static int alloc_counter(struct thunderx2_pmu_uncore_channel *pmu_uncore)
+{
+ int counter;
+
+ raw_spin_lock(&pmu_uncore->lock);
+ counter = find_first_zero_bit(pmu_uncore->active_counters,
+ pmu_uncore->uncore_dev->max_counters);
+ if (counter == pmu_uncore->uncore_dev->max_counters) {
+ raw_spin_unlock(&pmu_uncore->lock);
+ return -ENOSPC;
+ }
+ set_bit(counter, pmu_uncore->active_counters);
+ raw_spin_unlock(&pmu_uncore->lock);
+ return counter;
+}
+
+static void free_counter(
+ struct thunderx2_pmu_uncore_channel *pmu_uncore, int counter)

strange formatting

+{
+ raw_spin_lock(&pmu_uncore->lock);
+ clear_bit(counter, pmu_uncore->active_counters);
+ raw_spin_unlock(&pmu_uncore->lock);
+}
+

[ ... ]

+static void uncore_stop_event_l3c(struct perf_event *event)
+{
+ reg_writel(0, event->hw.config_base);
+}
+
+static void uncore_start_event_dmc(struct perf_event *event, int flags)
+{
+ u32 val;
+ struct hw_perf_event *hwc = &event->hw;
+ int idx = GET_COUNTERID(event);
+ int event_type = GET_EVENTID(event);
+
+ /* enable and start counters.
+ * 8 bits for each counter, bits[05:01] of a counter to set event type.
+ */
+ val = reg_readl(hwc->config_base);
+ val &= ~DMC_EVENT_CFG(idx, 0x1f);
+ val |= DMC_EVENT_CFG(idx, event_type);
+ reg_writel(val, hwc->config_base);
+ local64_set(&hwc->prev_count, 0);
+ reg_writel(0, hwc->event_base);
+}
+
+static void uncore_stop_event_dmc(struct perf_event *event)
+{
+ u32 val;
+ struct hw_perf_event *hwc = &event->hw;
+ int idx = GET_COUNTERID(event);
+
+ /* clear event type(bits[05:01]) to stop counter */
+ val = reg_readl(hwc->config_base);
+ val &= ~DMC_EVENT_CFG(idx, 0x1f);
+ reg_writel(val, hwc->config_base);
+}
+
+static void init_cntr_base_l3c(struct perf_event *event,
+ struct thunderx2_pmu_uncore_dev *uncore_dev)
+{
+ struct hw_perf_event *hwc = &event->hw;
+
+ /* counter ctrl/data reg offset at 8 */
+ hwc->config_base = (unsigned long)uncore_dev->base
+ + L3C_COUNTER_CTL + (8 * GET_COUNTERID(event));
+ hwc->event_base = (unsigned long)uncore_dev->base
+ + L3C_COUNTER_DATA + (8 * GET_COUNTERID(event));

Is there a better way to hold this, since we're casting back to a void * when writing to the register?

+}
+
+static void init_cntr_base_dmc(struct perf_event *event,
+ struct thunderx2_pmu_uncore_dev *uncore_dev)
+{
+ struct hw_perf_event *hwc = &event->hw;
+
+ hwc->config_base = (unsigned long)uncore_dev->base
+ + DMC_COUNTER_CTL;
+ /* counter data reg offset at 0xc */
+ hwc->event_base = (unsigned long)uncore_dev->base
+ + DMC_COUNTER_DATA + (0xc * GET_COUNTERID(event));
+}
+
+static void thunderx2_uncore_update(struct perf_event *event)
+{
+ s64 prev, new = 0;
+ u64 delta;
+ struct hw_perf_event *hwc = &event->hw;
+ struct thunderx2_pmu_uncore_channel *pmu_uncore;
+ enum thunderx2_uncore_type type;
+
+ pmu_uncore = pmu_to_thunderx2_pmu_uncore(event->pmu);
+ type = pmu_uncore->uncore_dev->type;
+
+ pmu_uncore->uncore_dev->select_channel(event);
+
+ new = reg_readl(hwc->event_base);
+ prev = local64_xchg(&hwc->prev_count, new);
+
+ /* handles rollover of 32 bit counter */
+ delta = (u32)(((1UL << 32) - prev) + new);
+ local64_add(delta, &event->count);
+}
+
+enum thunderx2_uncore_type get_uncore_device_type(struct acpi_device *adev)
+{
+ int i = 0;
+ struct acpi_uncore_device {
+ __u8 id[ACPI_ID_LEN];
+ enum thunderx2_uncore_type type;
+ } devices[] = {
+ {"CAV901D", PMU_TYPE_L3C},
+ {"CAV901F", PMU_TYPE_DMC},
+ {"", PMU_TYPE_INVALID},

for sentinels, ',' should not be required

+ };
+
+ while (devices[i].type != PMU_TYPE_INVALID) {
+ if (!strcmp(acpi_device_hid(adev), devices[i].id))
+ return devices[i].type;

Can't you use acpi_match_device()?

+ i++;
+ }
+ return PMU_TYPE_INVALID;
+}
+
+/*
+ * We must NOT create groups containing events from multiple hardware PMUs,
+ * although mixing different software and hardware PMUs is allowed.
+ */
+static bool thunderx2_uncore_validate_event_group(struct perf_event *event)

[ ... ]

+
+static int thunderx2_pmu_uncore_add(struct thunderx2_pmu_uncore_dev *uncore_dev,
+ int channel)
+{
+ struct thunderx2_pmu_uncore_channel *pmu_uncore;
+ int ret, cpu;
+
+ pmu_uncore = devm_kzalloc(uncore_dev->dev, sizeof(*pmu_uncore),
+ GFP_KERNEL);
+ if (!pmu_uncore)
+ return -ENOMEM;
+
+ cpu = cpumask_any_and(cpumask_of_node(uncore_dev->node),
+ cpu_online_mask);
+ if (cpu >= nr_cpu_ids)
+ return -EINVAL;
+
+ pmu_uncore->cpu = cpu;
+ pmu_uncore->channel = channel;
+ pmu_uncore->uncore_dev = uncore_dev;
+
+ hrtimer_init(&pmu_uncore->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ pmu_uncore->hrtimer.function = thunderx2_uncore_hrtimer_callback;
+
+ ret = thunderx2_pmu_uncore_register(pmu_uncore);
+ if (ret) {
+ dev_err(uncore_dev->dev, "%s PMU: Failed to init driver\n",
+ uncore_dev->name);
+ return -ENODEV;
+ }
+
+ /* register hotplug callback for the pmu */
+ ret = cpuhp_state_add_instance(
+ CPUHP_AP_PERF_ARM_THUNDERX2_UNCORE_ONLINE,
+ &pmu_uncore->node);
+ if (ret) {
+ dev_err(uncore_dev->dev, "Error %d registering hotplug", ret);
+ return ret;
+ }
+
+ dev_dbg(uncore_dev->dev, "%s PMU UNCORE registered\n",
+ pmu_uncore->pmu.name);

strange alignment, and many more times in the code

+ return ret;
+}
+
+static struct thunderx2_pmu_uncore_dev *init_pmu_uncore_dev(
+ struct device *dev, acpi_handle handle,
+ struct acpi_device *adev, u32 type)
+{
+ struct thunderx2_pmu_uncore_dev *uncore_dev;
+ void __iomem *base;
+ struct resource res;
+ struct resource_entry *rentry;
+ struct list_head list;
+ int ret;
+
+ INIT_LIST_HEAD(&list);
+ ret = acpi_dev_get_resources(adev, &list, NULL, NULL);
+ if (ret <= 0) {
+ dev_err(dev, "failed to parse _CRS method, error %d\n", ret);
+ return NULL;
+ }
+
+ list_for_each_entry(rentry, &list, node) {
+ if (resource_type(rentry->res) == IORESOURCE_MEM) {
+ res = *rentry->res;
+ break;
+ }
+ }

what I am missing that you can not use platform_get_resource(,IORESOURCE_MEM,)?

And I also wonder if you need all the device-related arguments for the code

+
+ if (!rentry->res)
+ return NULL;
+
+ acpi_dev_free_resource_list(&list);
+ base = devm_ioremap_resource(dev, &res);
+ if (IS_ERR(base)) {
+ dev_err(dev, "PMU type %d: Fail to map resource\n", type);
+ return NULL;
+ }
+
+ uncore_dev = devm_kzalloc(dev, sizeof(*uncore_dev), GFP_KERNEL);
+ if (!uncore_dev)
+ return NULL;
+
+ uncore_dev->dev = dev;
+ uncore_dev->type = type;
+ uncore_dev->base = base;
+ uncore_dev->node = dev_to_node(dev);
+
+ raw_spin_lock_init(&uncore_dev->lock);
+
+ switch (uncore_dev->type) {

if we can re-arrange, isn't it better to do the steps which can fail before the steps which can't?

+ case PMU_TYPE_L3C:
+ uncore_dev->max_counters = UNCORE_MAX_COUNTERS;
+ uncore_dev->max_channels = UNCORE_L3_MAX_TILES;
+ uncore_dev->max_events = L3_EVENT_MAX;
+ uncore_dev->hrtimer_interval = UNCORE_HRTIMER_INTERVAL;
+ uncore_dev->attr_groups = l3c_pmu_attr_groups;
+ uncore_dev->name = devm_kasprintf(dev, GFP_KERNEL,
+ "uncore_l3c_%d", uncore_dev->node);
+ uncore_dev->init_cntr_base = init_cntr_base_l3c;
+ uncore_dev->start_event = uncore_start_event_l3c;
+ uncore_dev->stop_event = uncore_stop_event_l3c;
+ uncore_dev->select_channel = uncore_select_channel;

it's possible to bring the common code outside the swicth statement, but probably not worth it

+ break;
+ case PMU_TYPE_DMC:
+ uncore_dev->max_counters = UNCORE_MAX_COUNTERS;
+ uncore_dev->max_channels = UNCORE_DMC_MAX_CHANNELS;
+ uncore_dev->max_events = DMC_EVENT_MAX;
+ uncore_dev->hrtimer_interval = UNCORE_HRTIMER_INTERVAL;
+ uncore_dev->attr_groups = dmc_pmu_attr_groups;
+ uncore_dev->name = devm_kasprintf(dev, GFP_KERNEL,
+ "uncore_dmc_%d", uncore_dev->node);
+ uncore_dev->init_cntr_base = init_cntr_base_dmc;
+ uncore_dev->start_event = uncore_start_event_dmc;
+ uncore_dev->stop_event = uncore_stop_event_dmc;
+ uncore_dev->select_channel = uncore_select_channel;
+ break;
+ case PMU_TYPE_INVALID:
+ devm_kfree(dev, uncore_dev);

do you really need this?

+ uncore_dev = NULL;
+ break;

return NULL

And don't we require a default statement?

+ }
+
+ return uncore_dev;
+}
+
+static acpi_status thunderx2_pmu_uncore_dev_add(acpi_handle handle, u32 level,
+ void *data, void **return_value)
+{
+ struct thunderx2_pmu_uncore_dev *uncore_dev;
+ struct acpi_device *adev;
+ enum thunderx2_uncore_type type;
+ int channel;
+
+ if (acpi_bus_get_device(handle, &adev))
+ return AE_OK;
+ if (acpi_bus_get_status(adev) || !adev->status.present)
+ return AE_OK;
+
+ type = get_uncore_device_type(adev);
+ if (type == PMU_TYPE_INVALID)
+ return AE_OK;
+
+ uncore_dev = init_pmu_uncore_dev((struct device *)data, handle,

no need to cast void *

+ adev, type);
+
+ if (!uncore_dev)
+ return AE_ERROR;
+
+ for (channel = 0; channel < uncore_dev->max_channels; channel++) {
+ if (thunderx2_pmu_uncore_add(uncore_dev, channel)) {
+ /* Can't add the PMU device, abort */
+ return AE_ERROR;
+ }
+ }
+ return AE_OK;
+}
+
+static int thunderx2_uncore_pmu_offline_cpu(unsigned int cpu,
+ struct hlist_node *node)
+{
+ int new_cpu;
+ struct thunderx2_pmu_uncore_channel *pmu_uncore;
+
+ pmu_uncore = hlist_entry_safe(node,
+ struct thunderx2_pmu_uncore_channel, node);
+ if (cpu != pmu_uncore->cpu)
+ return 0;
+
+ new_cpu = cpumask_any_and(
+ cpumask_of_node(pmu_uncore->uncore_dev->node),
+ cpu_online_mask);
+ if (new_cpu >= nr_cpu_ids)
+ return 0;
+
+ pmu_uncore->cpu = new_cpu;
+ perf_pmu_migrate_context(&pmu_uncore->pmu, cpu, new_cpu);
+ return 0;
+}
+
+static const struct acpi_device_id thunderx2_uncore_acpi_match[] = {
+ {"CAV901C", 0},
+ {},

no ',' required

+};
+MODULE_DEVICE_TABLE(acpi, thunderx2_uncore_acpi_match);
+
+static int thunderx2_uncore_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ acpi_handle handle;
+ acpi_status status;
+
+ set_dev_node(dev, acpi_get_node(ACPI_HANDLE(dev)));

Is this already done when the platform device is created in ACPI enumeration? I assume the child devices have enumerated at this point.

+
+ /* Make sure firmware supports DMC/L3C set channel smc call */
+ if (test_uncore_select_channel_early(dev))
+ return -ENODEV;
+
+ if (!has_acpi_companion(dev))
+ return -ENODEV;
+
+ handle = ACPI_HANDLE(dev);
+ if (!handle)
+ return -EINVAL;
+
+ /* Walk through the tree for all PMU UNCORE devices */
+ status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
+ thunderx2_pmu_uncore_dev_add,
+ NULL, dev, NULL);
+ if (ACPI_FAILURE(status)) {
+ dev_err(dev, "failed to probe PMU devices\n");
+ return_ACPI_STATUS(status);
+ }
+
+ dev_info(dev, "node%d: pmu uncore registered\n", dev_to_node(dev));
+ return 0;
+}
+
+static struct platform_driver thunderx2_uncore_driver = {
+ .probe = thunderx2_uncore_probe,

why no remove?

+ .driver = {
+ .name = "thunderx2-uncore-pmu",
+ .acpi_match_table = ACPI_PTR(thunderx2_uncore_acpi_match),
+ },
+};
+
+static int __init register_thunderx2_uncore_driver(void)
+{
+ int ret;
+
+ ret = cpuhp_setup_state_multi(CPUHP_AP_PERF_ARM_THUNDERX2_UNCORE_ONLINE,
+ "perf/tx2/uncore:online",
+ NULL,
+ thunderx2_uncore_pmu_offline_cpu);
+ if (ret)
+ return ret;
+
+ return platform_driver_register(&thunderx2_uncore_driver);
+
+}
+device_initcall(register_thunderx2_uncore_driver);
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 8796ba3..eb0c896 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -161,6 +161,7 @@ enum cpuhp_state {
CPUHP_AP_PERF_ARM_L2X0_ONLINE,
CPUHP_AP_PERF_ARM_QCOM_L2_ONLINE,
CPUHP_AP_PERF_ARM_QCOM_L3_ONLINE,
+ CPUHP_AP_PERF_ARM_THUNDERX2_UNCORE_ONLINE,
CPUHP_AP_PERF_POWERPC_NEST_IMC_ONLINE,
CPUHP_AP_PERF_POWERPC_CORE_IMC_ONLINE,
CPUHP_AP_PERF_POWERPC_THREAD_IMC_ONLINE,

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