LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Fabien Dessenne <fabien.dessenne@st.com>
To: Ohad Ben-Cohen <ohad@wizery.com>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Maxime Coquelin <mcoquelin.stm32@gmail.com>,
	Alexandre Torgue <alexandre.torgue@st.com>,
	Jonathan Corbet <corbet@lwn.net>,
	<linux-remoteproc@vger.kernel.org>, <devicetree@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>,
	<linux-stm32@st-md-mailman.stormreply.com>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-doc@vger.kernel.org>
Cc: Fabien Dessenne <fabien.dessenne@st.com>,
	Benjamin Gaignard <benjamin.gaignard@st.com>
Subject: [PATCH v2 0/6] hwspinlock: allow sharing of hwspinlocks
Date: Thu, 25 Apr 2019 11:17:17 +0200	[thread overview]
Message-ID: <1556183843-28033-1-git-send-email-fabien.dessenne@st.com> (raw)

The current implementation does not allow two different devices to use
a common hwspinlock. This patch set proposes to have, as an option, some
hwspinlocks shared between several users.

Below is an example that explain the need for this:
	exti: interrupt-controller@5000d000 {
		compatible = "st,stm32mp1-exti", "syscon";
		interrupt-controller;
		#interrupt-cells = <2>;
		reg = <0x5000d000 0x400>;
		hwlocks = <&hsem 1>;
	};
The two drivers (stm32mp1-exti and syscon) refer to the same hwlock.
With the current hwspinlock implementation, only the first driver succeeds
in requesting (hwspin_lock_request_specific) the hwlock. The second request
fails.


The proposed approach does not modify the API, but extends the DT 'hwlocks'
property with a second optional parameter (the first one identifies an
hwlock) that specifies whether an hwlock is requested for exclusive usage
(current behavior) or can be shared between several users.
Examples:
	hwlocks = <&hsem 8>;	Ref to hwlock #8 for exclusive usage
	hwlocks = <&hsem 8 0>;	Ref to hwlock #8 for exclusive (0) usage
	hwlocks = <&hsem 8 1>;	Ref to hwlock #8 for shared (1) usage

As a constraint, the #hwlock-cells value must be 1 or 2.
In the current implementation, this can have theorically any value but:
- all of the exisiting drivers use the same value : 1.
- the framework supports only one value : 1 (see implementation of
  of_hwspin_lock_simple_xlate())
Hence, it shall not be a problem to restrict this value to 1 or 2 since
it won't break any driver.

Changes since v1:
* Removed useless 'status = "okay"' from stm32mp157c.dtsi

Fabien Dessenne (6):
  dt-bindings: hwlock: add support of shared locks
  hwspinlock: allow sharing of hwspinlocks
  dt-bindings: hwlock: update STM32 #hwlock-cells value
  ARM: dts: stm32: Add hwspinlock node for stm32mp157 SoC
  ARM: dts: stm32: Add hwlock for irqchip on stm32mp157
  ARM: dts: stm32: hwlocks for GPIO for stm32mp157

 .../devicetree/bindings/hwlock/hwlock.txt          | 27 +++++--
 .../bindings/hwlock/st,stm32-hwspinlock.txt        |  6 +-
 Documentation/hwspinlock.txt                       | 10 ++-
 arch/arm/boot/dts/stm32mp157-pinctrl.dtsi          |  2 +
 arch/arm/boot/dts/stm32mp157c.dtsi                 |  9 +++
 drivers/hwspinlock/hwspinlock_core.c               | 82 +++++++++++++++++-----
 drivers/hwspinlock/hwspinlock_internal.h           |  2 +
 7 files changed, 107 insertions(+), 31 deletions(-)

-- 
2.7.4


             reply	other threads:[~2019-04-25  9:18 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-25  9:17 Fabien Dessenne [this message]
2019-04-25  9:17 ` [PATCH v2 1/6] dt-bindings: hwlock: add support of shared locks Fabien Dessenne
2019-04-25  9:17 ` [PATCH v2 2/6] hwspinlock: allow sharing of hwspinlocks Fabien Dessenne
2019-04-25  9:17 ` [PATCH v2 3/6] dt-bindings: hwlock: update STM32 #hwlock-cells value Fabien Dessenne
2019-04-25  9:17 ` [PATCH v2 4/6] ARM: dts: stm32: Add hwspinlock node for stm32mp157 SoC Fabien Dessenne
2019-04-25  9:17 ` [PATCH v2 5/6] ARM: dts: stm32: Add hwlock for irqchip on stm32mp157 Fabien Dessenne
2019-04-25  9:17 ` [PATCH v2 6/6] ARM: dts: stm32: hwlocks for GPIO for stm32mp157 Fabien Dessenne
2019-05-13  9:13 ` [PATCH v2 0/6] hwspinlock: allow sharing of hwspinlocks Fabien DESSENNE

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1556183843-28033-1-git-send-email-fabien.dessenne@st.com \
    --to=fabien.dessenne@st.com \
    --cc=alexandre.torgue@st.com \
    --cc=benjamin.gaignard@st.com \
    --cc=bjorn.andersson@linaro.org \
    --cc=corbet@lwn.net \
    --cc=devicetree@vger.kernel.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-remoteproc@vger.kernel.org \
    --cc=linux-stm32@st-md-mailman.stormreply.com \
    --cc=mark.rutland@arm.com \
    --cc=mcoquelin.stm32@gmail.com \
    --cc=ohad@wizery.com \
    --cc=robh+dt@kernel.org \
    --subject='Re: [PATCH v2 0/6] hwspinlock: allow sharing of hwspinlocks' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).