Hi Jeremy,

Jeremy Linton [off-list ref] writes:

Its possible that an ACPI system has multiple CPU types in it
with differing PMU counters. Iterate the CPU's and make a determination
about how many of each type exist in the system. Then take and create
a PMU platform device for each type, and assign it the interrupts parsed
from the MADT. Creating a platform device is necessary because the PMUs
are not described as devices in the DSDT table.

This code is loosely based on earlier work by Mark Salter.

Signed-off-by: Jeremy Linton <redacted>

Thanks for squashing changes to arm_pmu_acpi.c from different patches in
v6 into one patch. Except for the a function definition in Patch 5 that can
be moved here I think you've got everything. The combined patch is a lot
easier to review.

Some comments below.

Please add matching braces on both sides of the else.

[...]

The parenthesis around the conditions can be dropped.

+			pmu = kzalloc(sizeof(struct pmu_types), GFP_KERNEL);
+			if (!pmu) {
+				pr_warn("Unable to allocate pmu_types\n");
+				/*
+				 * continue to count cpus for any pmu_types
+				 * already allocated, but don't allocate any
+				 * more pmu_types. This avoids undercounting.
+				 */
+				alloc_failure = true;

Why not just fail probe and return an error? What is the benefit of
having some of the PMUs available?

+			} else {
+				pmu->cpu_type = partnum;
+				pmu->cpu_count++;
+				list_add_tail(&pmu->list, pmus);
+			}
+		}
+	}
+}
+
+/*
+ * Registers the group of PMU interfaces which correspond to the 'last_cpu_id'.
+ * This group utilizes 'count' resources in the 'res'.
+ */
+static int __init arm_pmu_acpi_register_pmu(int count, struct resource *res,
+					    int last_cpu_id)

Please drop the prefix "last_". AFAICS, it doesn't provide any
information.

+{
+	int i;
+	int err = -ENOMEM;
+	bool free_gsi = false;
+	struct platform_device *pdev;
+
+	if (count) {
+		pdev = platform_device_alloc(ARMV8_PMU_PDEV_NAME, last_cpu_id);
+		if (pdev) {
+			err = platform_device_add_resources(pdev, res, count);
+			if (!err) {
+				err = platform_device_add(pdev);
+				if (err) {
+					pr_warn("Unable to register PMU device\n");
+					free_gsi = true;
+				}
+			} else {
+				pr_warn("Unable to add resources to device\n");
+				free_gsi = true;
+				platform_device_put(pdev);
+			}
+		} else {
+			pr_warn("Unable to allocate platform device\n");
+			free_gsi = true;
+		}
+	}

This entire "if" block is quite hard to review.

Quoting Documentation/CodingStyle, "if you need more than 3 levels of
indentation, you're screwed anyway, and should fix your program."

+
+	/* unmark (and possibly unregister) registered GSIs */
+	for_each_possible_cpu(i) {
+		if (pmu_irqs[i].registered) {
+			if (free_gsi)
+				acpi_unregister_gsi(pmu_irqs[i].gsi);
+			pmu_irqs[i].registered = false;
+		}
+	}

Moving the for_each_possible_cpu block out of this function should help
makes things simpler. It doesn't have any connection to registering the
platform device and you could then do 

if (!count)
   return count;

which should help reduce a level of indentation. But you can further use
the same approach with other conditions in the block as well.

+
+	return err;
+}
+
+/*
+ * For the given cpu/pmu type, walk all known GSIs, register them, and add
+ * them to the resource structure. Return the number of GSI's contained
+ * in the res structure, and the id of the last CPU/PMU we added.
+ */
+static int __init arm_pmu_acpi_gsi_res(struct pmu_types *pmus,
+				       struct resource *res, int *last_cpu_id)
+{
+	int i, count;
+	int irq;
+
+	/* lets group all the PMU's from similar CPU's together */
+	count = 0;
+	for_each_possible_cpu(i) {
+		struct cpuinfo_arm64 *cinfo = per_cpu_ptr(&cpu_data, i);
+
+		if (pmus->cpu_type == MIDR_PARTNUM(cinfo->reg_midr)) {
+			if (pmu_irqs[i].gsi == 0)
+				continue;

Please don't silently continue if the irq is missing. It deserves a user
visible message. We don't want users complaining about kernel issues
when the firmware fails to provide the required information.

+
+			irq = acpi_register_gsi(NULL, pmu_irqs[i].gsi,
+						pmu_irqs[i].trigger,
+						ACPI_ACTIVE_HIGH);

Check for the return value of acpi_register_gsi as it can return an
error.

+
+			res[count].start = res[count].end = irq;
+			res[count].flags = IORESOURCE_IRQ;
+
+			if (pmu_irqs[i].trigger == ACPI_EDGE_SENSITIVE)
+				res[count].flags |= IORESOURCE_IRQ_HIGHEDGE;
+			else
+				res[count].flags |= IORESOURCE_IRQ_HIGHLEVEL;
+
+			pmu_irqs[i].registered = true;
+			count++;
+			(*last_cpu_id) = cinfo->reg_midr;

What is the benefit of using the entire MIDR for cpu_id when the
grouping is done on the basis of a subset, i.e., part number.

+		}
+	}
+	return count;
+}
+
 static int __init pmu_acpi_init(void)
 {
+	struct resource	*res;
 	int err = -ENOMEM;
+	int count, cpu_id;
+	struct pmu_types *pmu, *safe_temp;
+	LIST_HEAD(pmus);
 
 	if (acpi_disabled)
 		return 0;
 
+	arm_pmu_acpi_determine_cpu_types(&pmus);
+
+	list_for_each_entry_safe(pmu, safe_temp, &pmus, list) {
+		res = kcalloc(pmu->cpu_count,
+			      sizeof(struct resource), GFP_KERNEL);
+
+		/* for a given PMU type collect all the GSIs. */
+		if (res) {
+			count = arm_pmu_acpi_gsi_res(pmu, res,
+						     &cpu_id);
+			/*
+			 * register this set of interrupts
+			 * with a new PMU device
+			 */
+			err = arm_pmu_acpi_register_pmu(count, res, cpu_id);
+			if (!err)
+				pr_info("Registered %d devices for %X\n",
+					count, pmu->cpu_type);
+			kfree(res);
+		} else
+			pr_warn("PMU unable to allocate interrupt resource space\n");

Same comment about partial registration as above. It's better to error
out IMO.

Also if this stays, please use matching parenthesis on both sides of the else block.

Thanks,
Punit

+
+		list_del(&pmu->list);
+		kfree(pmu);
+	}
+
 	return err;
 }
+
 arch_initcall(pmu_acpi_init);