From: Sudeep Holla <sudeep.holla@arm.com>
To: Steven Price <steven.price@arm.com>
Cc: "linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
Arnd Bergmann <arnd@arndb.de>,
Mark Rutland <Mark.Rutland@arm.com>,
Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Harb Abdulhamid (harb@amperecomputing.com)"
<harb@amperecomputing.com>,
Francois Ozog <francois.ozog@linaro.org>,
Jose Marinho <Jose.Marinho@arm.com>,
Sudeep Holla <sudeep.holla@arm.com>,
Etienne Carriere <etienne.carriere@st.com>
Subject: Re: [PATCH v2] firmware: smccc: Add ARCH_SOC_ID support
Date: Wed, 17 Jun 2020 15:04:20 +0100 [thread overview]
Message-ID: <20200617140420.GA18881@bogus> (raw)
In-Reply-To: <ccbbae8d-8ca8-4688-4cec-58ae9962d766@arm.com>
On Wed, Jun 17, 2020 at 02:34:41PM +0100, Steven Price wrote:
> On 17/06/2020 11:05, Sudeep Holla wrote:
> > SMCCC v1.2 adds a new optional function SMCCC_ARCH_SOC_ID to obtain a
> > SiP defined SoC identification value. Add support for the same.
> >
> > Also using the SoC bus infrastructure, let us expose the platform
> > specific SoC atrributes under sysfs.
> >
> > There are various ways in which it can be represented in shortened form
> > for efficiency and ease of parsing for userspace. The chosen form is
> > described in the ABI document.
> >
> > Cc: Steven Price <steven.price@arm.com>
> > Cc: Etienne Carriere <etienne.carriere@st.com>
> > Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
> > ---
> > Documentation/ABI/testing/sysfs-devices-soc | 30 ++++++
> > drivers/firmware/smccc/Kconfig | 9 ++
> > drivers/firmware/smccc/Makefile | 1 +
> > drivers/firmware/smccc/soc_id.c | 114 ++++++++++++++++++++
> > include/linux/arm-smccc.h | 5 +
> > 5 files changed, 159 insertions(+)
> > create mode 100644 drivers/firmware/smccc/soc_id.c
> >
> > Changes from v1[1] -> v2:
> > - Dropped new jep106_id added to SoC infrastructure
> > - Dropped all the tags(acks/reviews) as there is change in the format
> > - Updated the format for SoC id to ensure there will be no
> > conflict in the namespace
> >
> > [1] https://lore.kernel.org/lkml/20200522124951.35776-1-sudeep.holla@arm.com/
> >
> > diff --git a/Documentation/ABI/testing/sysfs-devices-soc b/Documentation/ABI/testing/sysfs-devices-soc
> > index ba3a3fac0ee1..50707f316ea9 100644
> > --- a/Documentation/ABI/testing/sysfs-devices-soc
> > +++ b/Documentation/ABI/testing/sysfs-devices-soc
> > @@ -26,6 +26,30 @@ contact: Lee Jones <lee.jones@linaro.org>
> > 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 can be shortened
>
> NIT: s/can be/is/ - since the format always uses the short form.
>
Will fix it.
[...]
> > +
> > + sprintf(soc_id_rev_str, "0x%08x", soc_id_rev);
> > + sprintf(soc_id_jep106_id_str, "jep106:%02x%02x",
> > + JEP106_BANK_CONT_CODE(soc_id_version),
> > + JEP106_ID_CODE(soc_id_version));
> > + sprintf(soc_id_str, "%s:%04x", soc_id_jep106_id_str,
> > + IMP_DEF_SOC_ID(soc_id_version));
>
> My maths might be wrong, but I think this is one byte too long:
>
> soc_id_jep106_id_str can be 11 characters (without the NUL), then we have a
> ':' byte followed by 4 hex digits and a trailing NUL: 11 + 1 + 4 + 1 = 17,
> but the char array is 16 bytes long.
>
Nope, you are right. I was changing the format multiple times without
bothering much about that size. Thanks for the catch.
> With that fixed feel free to add my "Reviewed-by".
>
I will fix it up and thanks for the review.
--
Regards,
Sudeep
prev parent reply other threads:[~2020-06-17 14:04 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-17 10:05 [PATCH v2] firmware: smccc: Add ARCH_SOC_ID support Sudeep Holla
2020-06-17 13:34 ` Steven Price
2020-06-17 14:04 ` Sudeep Holla [this message]
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