The current DT binding description is misleading and confusing. Clarify
the text and provide more examples.
Signed-off-by: Atish Patra <atishp at rivosinc.com>
---
docs/pmu_support.md | 46 ++++++++++++++++++++++++++++-----------------
1 file changed, 29 insertions(+), 17 deletions(-)
diff --git a/docs/pmu_support.md b/docs/pmu_support.md
index 7e3367cffe71..36349ed6ec9e 100644
--- a/docs/pmu_support.md
+++ b/docs/pmu_support.md
@@ -51,19 +51,16 @@ shouldn't encode any raw event.
* **riscv,raw-event-to-mhpmcounters**(Optional) - It represents an ONE-to-MANY
or MANY-to-MANY mapping between the raw event(s) and all the MHPMCOUNTERx in
-a bitmap format that can be used to monitor that raw event, which depends on
-how the platform encodes the monitor events. Currently, only the following three
-encoding methods are supported, encoding each event as a number, using a bitmap
-to encode monitor events, and mixing the previous two methods. The information
-is encoded in a table format where each row represent the specific raw event(s).
-The first column represents a 64-bit selector value which can indicate an
-monitor event ID (encoded by a number) or an event set (encoded by a bitmap).
-In case of the latter, the lower bits used to encode a set of events should be
-set to zero. The second column is a 64-bit selector mask where any bits used
-for event encoding will be cleared. If a platform directly encodes each raw PMU
-event as a unique ID, the value of select_mask will be 0xffffffff_ffffffff.
-The third column represent a bitmap of all the MHPMCOUNTERx that can be used for
-monitoring the specified event(s).
+a bitmap format that can be used to monitor that raw event. The encoding of the
+raw events are platform specific. The information is encoded in a table format
+where each row represent the specific raw event(s). The first column is a 64bit
+match value where the invariant bits of range of events are set. The second
+column is a 64 bit mask that will have all the variant bits of the range of
+events cleared. Every other bits should be set in the mask.
+The third column is a 32bit value to represent bitmap of all MHPMCOUNTERx that
+can monitor these set of event(s).
+If a platform directly encodes each raw PMU event as a unique ID, the value of
+select_mask must be 0xffffffff_ffffffff.
*Note:* A platform may choose to provide the mapping between event & counters
via platform hooks rather than the device tree.
@@ -73,15 +70,30 @@ via platform hooks rather than the device tree.
```
pmu {
compatible = "riscv,pmu";
- interrupts = <0x100>;
- interrupt-parent = <&plic>
riscv,event-to-mhpmevent = <0x0000B 0x0000 0x0001>,
riscv,event-to-mhpmcounters = <0x00001 0x00001 0x00000001>,
<0x00002 0x00002 0x00000004>,
<0x00003 0x0000A 0x00000ff8>,
<0x10000 0x10033 0x000ff000>,
- riscv,raw-event-to-mhpmcounters = <0x0000 0x0002 0xffffffff 0xffffffff 0x00000f8>,
- <0xffffffff 0xfffffff0 0xffffffff 0xfffffff0 0x00000ff0>,
+ /* For event ID 0x0002 */
+ riscv,raw-event-to-mhpmcounters = <0x0000 0x0002 0xffffffff 0xffffffff 0x00000f8>,
+ /* For event ID 0-4 */
+ <0x0 0x0 0xffffffff 0xfffffff0 0x00000ff0>,
+ /* For event ID 0xffffffff0000000f - 0xffffffff000000ff */
+ <0xffffffff 0x0 0xffffffff 0xffffff0f 0x00000ff0>,
+
};
+/* For HiFive Unmatched board. The encodings can be found here
+ * https://sifive.cdn.prismic.io/sifive/1a82e600-1f93-4f41-b2d8-86ed8b16acba_fu740-c000-manual-v1p6.pdf
+ */
+
+pmu {
+ compatible = "riscv,pmu";
+ riscv,raw-event-to-mhpmcounters = <0x0 0x0 0xffffffff 0xfff800ff 0xc>,
+ <0x0 0x1 0xffffffff 0xffffc00ff 0xc>,
+ <0x0 0x2 0xffffffff 0xfffffeff 0xc>,
+};
+
+
```
--
2.25.1