| Message ID | 1650302327-30439-1-git-send-email-quic_jhugo@quicinc.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | [v3] bus: mhi: host: Add soc_reset sysfs | expand |
On Mon, Apr 18, 2022 at 11:18:47AM -0600, Jeffrey Hugo wrote: > The MHI bus supports a standardized hardware reset, which is known as the > "SoC Reset". This reset is similar to the reset sysfs for PCI devices - > a hardware mechanism to reset the state back to square one. > > The MHI SoC Reset is described in the spec as a reset of last resort. If > some unrecoverable error has occurred where other resets have failed, SoC > Reset is the "big hammer" that ungracefully resets the device. This is > effectivly the same as yanking the power on the device, and reapplying it. > However, depending on the nature of the particular issue, the underlying > transport link may remain active and configured. If the link remains up, > the device will flag a MHI system error early in the boot process after > the reset is executed, which allows the MHI bus to process a fatal error > event, and clean up appropiately. > > While the SoC Reset is generally intended as a means of recovery when all > else has failed, it can be useful in non-error scenarios. For example, > if the device loads firmware from the host filesystem, the device may need > to be fully rebooted inorder to pick up the new firmware. In this > scenario, the system administrator may use the soc_reset sysfs to cause > the device to pick up the new firmware that the admin placed on the > filesystem. > > Signed-off-by: Jeffrey Hugo <quic_jhugo@quicinc.com> > Reviewed-by: Bhaumik Bhatt <quic_bbhatt@quicinc.com> > Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org> Applied to mhi-next! Thanks, Mani > --- > > v3: > Cleanup email domain change > > v2: > Rebase > > Documentation/ABI/stable/sysfs-bus-mhi | 10 ++++++++++ > drivers/bus/mhi/host/init.c | 14 ++++++++++++++ > 2 files changed, 24 insertions(+) > > diff --git a/Documentation/ABI/stable/sysfs-bus-mhi b/Documentation/ABI/stable/sysfs-bus-mhi > index ecfe766..96ccc33 100644 > --- a/Documentation/ABI/stable/sysfs-bus-mhi > +++ b/Documentation/ABI/stable/sysfs-bus-mhi > @@ -19,3 +19,13 @@ Description: The file holds the OEM PK Hash value of the endpoint device > read without having the device power on at least once, the file > will read all 0's. > Users: Any userspace application or clients interested in device info. > + > +What: /sys/bus/mhi/devices/.../soc_reset > +Date: April 2022 > +KernelVersion: 5.19 > +Contact: mhi@lists.linux.dev > +Description: Initiates a SoC reset on the MHI controller. A SoC reset is > + a reset of last resort, and will require a complete re-init. > + This can be useful as a method of recovery if the device is > + non-responsive, or as a means of loading new firmware as a > + system administration task. > diff --git a/drivers/bus/mhi/host/init.c b/drivers/bus/mhi/host/init.c > index a665b8e..a8c18c5f 100644 > --- a/drivers/bus/mhi/host/init.c > +++ b/drivers/bus/mhi/host/init.c > @@ -108,9 +108,23 @@ static ssize_t oem_pk_hash_show(struct device *dev, > } > static DEVICE_ATTR_RO(oem_pk_hash); > > +static ssize_t soc_reset_store(struct device *dev, > + struct device_attribute *attr, > + const char *buf, > + size_t count) > +{ > + struct mhi_device *mhi_dev = to_mhi_device(dev); > + struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl; > + > + mhi_soc_reset(mhi_cntrl); > + return count; > +} > +static DEVICE_ATTR_WO(soc_reset); > + > static struct attribute *mhi_dev_attrs[] = { > &dev_attr_serial_number.attr, > &dev_attr_oem_pk_hash.attr, > + &dev_attr_soc_reset.attr, > NULL, > }; > ATTRIBUTE_GROUPS(mhi_dev); > -- > 2.7.4 >
diff --git a/Documentation/ABI/stable/sysfs-bus-mhi b/Documentation/ABI/stable/sysfs-bus-mhi index ecfe766..96ccc33 100644 --- a/Documentation/ABI/stable/sysfs-bus-mhi +++ b/Documentation/ABI/stable/sysfs-bus-mhi @@ -19,3 +19,13 @@ Description: The file holds the OEM PK Hash value of the endpoint device read without having the device power on at least once, the file will read all 0's. Users: Any userspace application or clients interested in device info. + +What: /sys/bus/mhi/devices/.../soc_reset +Date: April 2022 +KernelVersion: 5.19 +Contact: mhi@lists.linux.dev +Description: Initiates a SoC reset on the MHI controller. A SoC reset is + a reset of last resort, and will require a complete re-init. + This can be useful as a method of recovery if the device is + non-responsive, or as a means of loading new firmware as a + system administration task. diff --git a/drivers/bus/mhi/host/init.c b/drivers/bus/mhi/host/init.c index a665b8e..a8c18c5f 100644 --- a/drivers/bus/mhi/host/init.c +++ b/drivers/bus/mhi/host/init.c @@ -108,9 +108,23 @@ static ssize_t oem_pk_hash_show(struct device *dev, } static DEVICE_ATTR_RO(oem_pk_hash); +static ssize_t soc_reset_store(struct device *dev, + struct device_attribute *attr, + const char *buf, + size_t count) +{ + struct mhi_device *mhi_dev = to_mhi_device(dev); + struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl; + + mhi_soc_reset(mhi_cntrl); + return count; +} +static DEVICE_ATTR_WO(soc_reset); + static struct attribute *mhi_dev_attrs[] = { &dev_attr_serial_number.attr, &dev_attr_oem_pk_hash.attr, + &dev_attr_soc_reset.attr, NULL, }; ATTRIBUTE_GROUPS(mhi_dev);