feat(amu): enable per-core AMU auxiliary counters
This change makes AMU auxiliary counters configurable on a per-core
basis, controlled by `ENABLE_AMU_AUXILIARY_COUNTERS`.
Auxiliary counters can be described via the `HW_CONFIG` device tree if
the `ENABLE_AMU_FCONF` build option is enabled, or the platform must
otherwise implement the `plat_amu_topology` function.
A new phandle property for `cpu` nodes (`amu`) has been introduced to
the `HW_CONFIG` specification to allow CPUs to describe the view of
their own AMU:
```
cpu0: cpu@0 {
...
amu = <&cpu0_amu>;
};
```
Multiple cores may share an `amu` handle if they implement the
same set of auxiliary counters.
AMU counters are described for one or more AMUs through the use of a new
`amus` node:
```
amus {
cpu0_amu: amu-0 {
#address-cells = <1>;
#size-cells = <0>;
counter@0 {
reg = <0>;
enable-at-el3;
};
counter@n {
reg = <n>;
...
};
};
};
```
This structure describes the **auxiliary** (group 1) AMU counters.
Architected counters have architecturally-defined behaviour, and as
such do not require DTB entries.
These `counter` nodes support two properties:
- The `reg` property represents the counter register index.
- The presence of the `enable-at-el3` property determines whether
the firmware should enable the counter prior to exiting EL3.
Change-Id: Ie43aee010518c5725a3b338a4899b0857caf4c28
Signed-off-by: Chris Kay <chris.kay@arm.com>
diff --git a/lib/fconf/fconf_amu_getter.c b/lib/fconf/fconf_amu_getter.c
new file mode 100644
index 0000000..eff309c
--- /dev/null
+++ b/lib/fconf/fconf_amu_getter.c
@@ -0,0 +1,142 @@
+/*
+ * Copyright (c) 2021, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <common/debug.h>
+#include <common/fdt_wrappers.h>
+#include <lib/fconf/fconf.h>
+#include <lib/fconf/fconf_amu_getter.h>
+#include <libfdt.h>
+
+#include <plat/common/platform.h>
+
+struct fconf_amu_config fconf_amu_config;
+static struct amu_topology fconf_amu_topology_;
+
+/*
+ * Populate the core-specific AMU structure with information retrieved from a
+ * device tree.
+ *
+ * Returns `0` on success, or a negative integer representing an error code.
+ */
+static int fconf_populate_amu_cpu_amu(const void *fdt, int parent,
+ struct amu_core *amu)
+{
+ int ret = 0;
+ int node = 0;
+
+ fdt_for_each_subnode(node, fdt, parent) {
+ const char *name;
+ const char *value;
+ int len;
+
+ uintptr_t idx = 0U;
+
+ name = fdt_get_name(fdt, node, &len);
+ if (strncmp(name, "counter@", 8) != 0) {
+ continue;
+ }
+
+ ret = fdt_get_reg_props_by_index(fdt, node, 0, &idx, NULL);
+ if (ret < 0) {
+ break;
+ }
+
+ value = fdt_getprop(fdt, node, "enable-at-el3", &len);
+ if ((value == NULL) && (len != -FDT_ERR_NOTFOUND)) {
+ break;
+ }
+
+ if (len != -FDT_ERR_NOTFOUND) {
+ amu->enable |= (1 << idx);
+ }
+ }
+
+ if ((node < 0) && (node != -FDT_ERR_NOTFOUND)) {
+ return node;
+ }
+
+ return ret;
+}
+
+/*
+ * Within a `cpu` node, attempt to dereference the `amu` property, and populate
+ * the AMU information for the core.
+ *
+ * Returns `0` on success, or a negative integer representing an error code.
+ */
+static int fconf_populate_amu_cpu(const void *fdt, int node, uintptr_t mpidr)
+{
+ int ret;
+ int idx;
+
+ uint32_t amu_phandle;
+ struct amu_core *amu;
+
+ ret = fdt_read_uint32(fdt, node, "amu", &amu_phandle);
+ if (ret < 0) {
+ if (ret == -FDT_ERR_NOTFOUND) {
+ ret = 0;
+ }
+
+ return ret;
+ }
+
+ node = fdt_node_offset_by_phandle(fdt, amu_phandle);
+ if (node < 0) {
+ return node;
+ }
+
+ idx = plat_core_pos_by_mpidr(mpidr);
+ if (idx < 0) {
+ return -FDT_ERR_BADVALUE;
+ }
+
+ amu = &fconf_amu_topology_.cores[idx];
+
+ return fconf_populate_amu_cpu_amu(fdt, node, amu);
+}
+
+/*
+ * Populates the global `amu_topology` structure based on what's described by
+ * the hardware configuration device tree blob.
+ *
+ * The device tree is expected to provide an `amu` property for each `cpu` node,
+ * like so:
+ *
+ * cpu@0 {
+ * amu = <&cpu0_amu>;
+ * };
+ *
+ * amus {
+ * cpu0_amu: amu-0 {
+ * counters {
+ * #address-cells = <2>;
+ * #size-cells = <0>;
+ *
+ * counter@x,y {
+ * reg = <x y>; // Group x, counter y
+ * };
+ * };
+ * };
+ * };
+ */
+static int fconf_populate_amu(uintptr_t config)
+{
+ int ret = fdtw_for_each_cpu(
+ (const void *)config, fconf_populate_amu_cpu);
+ if (ret == 0) {
+ fconf_amu_config.topology = &fconf_amu_topology_;
+ } else {
+ ERROR("FCONF: failed to parse AMU information: %d\n", ret);
+ }
+
+ return ret;
+}
+
+FCONF_REGISTER_POPULATOR(HW_CONFIG, amu, fconf_populate_amu);