Messages in this thread Patch in this message | | | Subject | Re: [PATCH] cros_ec: instantiate properly Intel ISH MCU device | From | Enric Balletbo i Serra <> | Date | Wed, 27 Feb 2019 15:22:03 +0100 |
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Hi,
On 26/2/19 18:21, Jett Rink wrote: > We are specifically wanting userspace applications to not worry/confuse cros_ish > with a normal cros_ec. Adding an attribute instead of changing the path would > make it easy for userspace application to forget to check properly before > accessing the ish as an EC when it shouldn't. > > On Mon, Feb 25, 2019 at 4:37 PM Guenter Roeck <groeck@google.com > <mailto:groeck@google.com>> wrote: > > On Mon, Feb 25, 2019 at 3:22 PM Jett Rink <jettrink@chromium.org > <mailto:jettrink@chromium.org>> wrote: > > A cros_ec and cros_ish device could both be present on the same system. > We want to change the device path to ensure that drivers/code further up > the stack does not get confuse the ISH with as an EC. > > The ISH device can export a similar sysfs interface as they both use the > same command interface for communication (although they will use > different transport layers). The common cros code will detect certain > EC_FEATURES and enable the correct subsystem based on the level of > functionality the device supports. In the case of the ISH, the sensor > subsystem will be enabled. > > Seems to me it would make more sense to handle that difference with a sysfs > attribute (instead of forcing each userspace application to support multiple > sysfs paths). >
Is still unclear to me what's that ISH device, so I'd appreciate if you can give some more background. Trying to understand the topology, makes sense that block diagram to you?
--------------------------- | User Space Applications | ---------------------------
----------------IIO ABI----------------
----------------------------- | CrOS EC IIO Sensor Drivers | -----------------------------
-------------------------- | CrOS EC over ISH Driver | --------------------------
---------------- OS ------------------
-------------------------- | CrOS EC Firmware | --------------------------
-------------------------- | ISH Hardware/Firmware | --------------------------
So I'm right assuming that this CrOS EC will implement only the sensor features?
And then, the system will have another CrOS EC implementing other features like RTC, USBPD-charger, etc?
Apart from the sensors features, will the CrOS EC ISH implement other features?
I'm a bit worried about the increasing way to use a particular name for different CrOS EC, actually we have only cros_ec and cros_pd. But in the chromeos kernels there is /dev/cros_fp, /dev/cros_tp, /dev/cros_ish, /dev/cros_scp and who knows how many more in the future. So I'm wondering if wouldn't be better use standard names, i.e /dev/cros_ec0, /dev/cros_ec1, etc. as userspace, for those cases, should be able to query the EC_FEATURE_ISH/FP/TP/SCP and know against which EC the device is attached.
Cheers, Enric
> Guenter > > > -Jett > > On Sun, Feb 24, 2019 at 4:03 PM Guenter Roeck <groeck@google.com > <mailto:groeck@google.com>> wrote: > > On Sun, Feb 24, 2019 at 1:14 AM Rushikesh S Kadam > <rushikesh.s.kadam@intel.com <mailto:rushikesh.s.kadam@intel.com>> > wrote: > > Intel Integrated Sensor Hub (ISH) is also a MCU running EC > having feature bit EC_FEATURE_ISH. Instantiate it as a special > CrOS EC device with device name 'cros_ish'. > > > The type of MCU doesn't really have to be reflected in the sysfs > directory path. cros_ec uses different > MCUs over time. > > Will the new path exist in parallel with cros_ec (in other words, > will there also be a stand-alone EC in the same system) ? Does it > have different or the same sysfs attributes as cros_ec ? > > Also,, what is the impact on userspace ? > > Thanks, > Guenter > > Signed-off-by: Rushikesh S Kadam <rushikesh.s.kadam@intel.com > <mailto:rushikesh.s.kadam@intel.com>> > --- > drivers/mfd/cros_ec_dev.c | 10 ++++++++++ > include/linux/mfd/cros_ec.h | 1 + > include/linux/mfd/cros_ec_commands.h | 2 ++ > 3 files changed, 13 insertions(+) > > diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c > index 2d0fee4..be499b8 100644 > --- a/drivers/mfd/cros_ec_dev.c > +++ b/drivers/mfd/cros_ec_dev.c > @@ -414,6 +414,16 @@ static int ec_device_probe(struct > platform_device *pdev) > device_initialize(&ec->class_dev); > cdev_init(&ec->cdev, &fops); > > + /* check whether this is actually a Intel ISH rather > than an EC */ > + if (cros_ec_check_features(ec, EC_FEATURE_ISH)) { > + dev_info(dev, "Intel ISH MCU detected.\n"); > + /* > + * Help userspace differentiating ECs from ISH MCU, > + * regardless of the probing order. > + */ > + ec_platform->ec_name = CROS_EC_DEV_ISH_NAME; > + } > + > /* > * Add the class device > * Link to the character device for creating the /dev entry > diff --git a/include/linux/mfd/cros_ec.h > b/include/linux/mfd/cros_ec.h > index de8b588..00c5765 100644 > --- a/include/linux/mfd/cros_ec.h > +++ b/include/linux/mfd/cros_ec.h > @@ -24,6 +24,7 @@ > > #define CROS_EC_DEV_NAME "cros_ec" > #define CROS_EC_DEV_PD_NAME "cros_pd" > +#define CROS_EC_DEV_ISH_NAME "cros_ish" > > /* > * The EC is unresponsive for a time after a reboot command. Add a > diff --git a/include/linux/mfd/cros_ec_commands.h > b/include/linux/mfd/cros_ec_commands.h > index fc91082..9276c3c 100644 > --- a/include/linux/mfd/cros_ec_commands.h > +++ b/include/linux/mfd/cros_ec_commands.h > @@ -856,6 +856,8 @@ enum ec_feature_code { > EC_FEATURE_RTC = 27, > /* EC supports CEC commands */ > EC_FEATURE_CEC = 35, > + /* The MCU is an Intel Integrated Sensor Hub */ > + EC_FEATURE_ISH = 40, > }; > > #define EC_FEATURE_MASK_0(event_code) (1UL << (event_code % 32)) > -- > 1.9.1 >
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