From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Subject: Re: [RESEND PATCH 6/7] i2c: ChromeOS EC tunnel driver Date: Mon, 21 Apr 2014 11:53:00 -0600 Message-ID: <53555AFC.5020203@wwwdotorg.org> References: <1397759814-3588-1-git-send-email-dianders@chromium.org> <1397759814-3588-7-git-send-email-dianders@chromium.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1397759814-3588-7-git-send-email-dianders@chromium.org> Sender: linux-doc-owner@vger.kernel.org To: Doug Anderson , lee.jones@linaro.org, swarren@nvidia.com, wsa@the-dreams.de Cc: abrestic@chromium.org, dgreid@chromium.org, olof@lixom.net, sjg@chromium.org, linux-samsung-soc@vger.kernel.org, linux-tegra@vger.kernel.org, Vincent Palatin , robh+dt@kernel.org, pawel.moll@arm.com, mark.rutland@arm.com, ijc+devicetree@hellion.org.uk, galak@codeaurora.org, rdunlap@infradead.org, sameo@linux.intel.com, jdelvare@suse.de, shane.huang@amd.com, maxime.ripard@free-electrons.com, laurent.pinchart+renesas@ideasonboard.com, u.kleine-koenig@pengutronix.de, bjorn.andersson@sonymobile.com, kevin.strasser@linux.intel.com, linux@prisktech.co.nz, andrew@lunn.ch, andriy.shevchenko@linux.intel.com, schwidefsky@de.ibm.com, matt.porter@linaro.org, ch.naveen@samsung.com, devicetree@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org List-Id: devicetree@vger.kernel.org On 04/17/2014 12:36 PM, Doug Anderson wrote: > On ARM Chromebooks we have a few devices that are accessed by both the > AP (the main "Application Processor") and the EC (the Embedded > Controller). These are: > * The battery (sbs-battery). > * The power management unit tps65090. ... > On the Samsung ARM Chromebook 2 the scheme is changed yet again, now: > * The AP/EC comms are now using SPI for faster speeds. > * The EC's i2c bus is exposed to the AP through a full i2c tunnel. ... > This driver supports the scheme used by the Samsung ARM Chromebook 2. > Future patches to this driver could add support for the battery tunnel > on the HP Chromebook 11 (and perhaps could even be used to access > tps65090 on the HP Chromebook 11 instead of using a special driver, > but I haven't researched that enough). > diff --git a/Documentation/devicetree/bindings/i2c/i2c-cros-ec-tunnel.txt b/Documentation/devicetree/bindings/i2c/i2c-cros-ec-tunnel.txt > +I2C bus that tunnels through the ChromeOS EC (cros-ec) > +====================================================== > +On some ChromeOS board designs we've got a connection to the EC (embedded > +controller) but no direct connection to some devices on the other side of > +the EC (like a battery and PMIC). To get access to those devices we need > +to tunnel our i2c commands through the EC. > + > +The node for this device should be under a cros-ec node like google,cros-ec-spi > +or google,cros-ec-i2c. > + > + > +Required properties: > +- compatible: google,cros-ec-i2c-tunnel > +- google,remote-bus: The EC bus we'd like to talk to. It's probably worth mentioning here that the node represents a single I2C bus, and hence is expected to contain child nodes representing I2C devices. Perhaps: Optional child nodes: - One node per I2C device connected to the tunnelled I2C bus.