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-rw-r--r--Documentation/ABI/testing/sysfs-devices-soc30
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diff --git a/Documentation/ABI/testing/sysfs-devices-soc b/Documentation/ABI/testing/sysfs-devices-soc
index ba3a3fac0ee1..ea999e292f11 100644
--- a/Documentation/ABI/testing/sysfs-devices-soc
+++ b/Documentation/ABI/testing/sysfs-devices-soc
@@ -26,6 +26,30 @@ Description:
Read-only attribute common to all SoCs. Contains SoC family name
(e.g. DB8500).
+ On many of ARM based silicon with SMCCC v1.2+ compliant firmware
+ this will contain the JEDEC JEP106 manufacturer’s identification
+ code. The format is "jep106:XXYY" where XX is identity code and
+ YY is continuation code.
+
+ This manufacturer’s identification code is defined by one
+ or more eight (8) bit fields, each consisting of seven (7)
+ data bits plus one (1) odd parity bit. It is a single field,
+ limiting the possible number of vendors to 126. To expand
+ the maximum number of identification codes, a continuation
+ scheme has been defined.
+
+ The specified mechanism is that an identity code of 0x7F
+ represents the "continuation code" and implies the presence
+ of an additional identity code field, and this mechanism
+ may be extended to multiple continuation codes followed
+ by the manufacturer's identity code.
+
+ For example, ARM has identity code 0x7F 0x7F 0x7F 0x7F 0x3B,
+ which is code 0x3B on the fifth 'page'. This is shortened
+ as JEP106 identity code of 0x3B and a continuation code of
+ 0x4 to represent the four continuation codes preceding the
+ identity code.
+
What: /sys/devices/socX/serial_number
Date: January 2019
contact: Bjorn Andersson <bjorn.andersson@linaro.org>
@@ -40,6 +64,12 @@ Description:
Read-only attribute supported by most SoCs. In the case of
ST-Ericsson's chips this contains the SoC serial number.
+ On many of ARM based silicon with SMCCC v1.2+ compliant firmware
+ this will contain the SOC ID appended to the family attribute
+ to ensure there is no conflict in this namespace across various
+ vendors. The format is "jep106:XXYY:ZZZZ" where XX is identity
+ code, YY is continuation code and ZZZZ is the SOC ID.
+
What: /sys/devices/socX/revision
Date: January 2012
contact: Lee Jones <lee.jones@linaro.org>