Re: [PATCH v3 03/16] bus: mhi: core: Add support for registering MHI client drivers

[Jeffrey Hugo <jhugo@codeaurora.org>]

On 3/18/2020 7:36 AM, Greg KH wrote:
> On Thu, Feb 20, 2020 at 03:28:41PM +0530, Manivannan Sadhasivam wrote:
>> This commit adds support for registering MHI client drivers with the
>> MHI stack. MHI client drivers binds to one or more MHI devices inorder
>> to sends and receive the upper-layer protocol packets like IP packets,
>> modem control messages, and diagnostics messages over MHI bus.
>>
>> This is based on the patch submitted by Sujeev Dias:
>> https://lkml.org/lkml/2018/7/9/987
>>
>> Signed-off-by: Sujeev Dias <sdias@codeaurora.org>
>> Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>
>> [mani: splitted and cleaned up for upstream]
>> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
>> Reviewed-by: Jeffrey Hugo <jhugo@codeaurora.org>
>> Tested-by: Jeffrey Hugo <jhugo@codeaurora.org>
>> ---
>>   drivers/bus/mhi/core/init.c | 149 ++++++++++++++++++++++++++++++++++++
>>   include/linux/mhi.h         |  39 ++++++++++
>>   2 files changed, 188 insertions(+)
>>
>> diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
>> index 6f24c21284ec..12e386862b3f 100644
>> --- a/drivers/bus/mhi/core/init.c
>> +++ b/drivers/bus/mhi/core/init.c
>> @@ -374,8 +374,157 @@ struct mhi_device *mhi_alloc_device(struct mhi_controller *mhi_cntrl)
>>   	return mhi_dev;
>>   }
>>   
>> +static int mhi_driver_probe(struct device *dev)
>> +{
>> +	struct mhi_device *mhi_dev = to_mhi_device(dev);
>> +	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
>> +	struct device_driver *drv = dev->driver;
>> +	struct mhi_driver *mhi_drv = to_mhi_driver(drv);
>> +	struct mhi_event *mhi_event;
>> +	struct mhi_chan *ul_chan = mhi_dev->ul_chan;
>> +	struct mhi_chan *dl_chan = mhi_dev->dl_chan;
>> +
>> +	if (ul_chan) {
>> +		/*
>> +		 * If channel supports LPM notifications then status_cb should
>> +		 * be provided
>> +		 */
>> +		if (ul_chan->lpm_notify && !mhi_drv->status_cb)
>> +			return -EINVAL;
>> +
>> +		/* For non-offload channels then xfer_cb should be provided */
>> +		if (!ul_chan->offload_ch && !mhi_drv->ul_xfer_cb)
>> +			return -EINVAL;
>> +
>> +		ul_chan->xfer_cb = mhi_drv->ul_xfer_cb;
>> +	}
>> +
>> +	if (dl_chan) {
>> +		/*
>> +		 * If channel supports LPM notifications then status_cb should
>> +		 * be provided
>> +		 */
>> +		if (dl_chan->lpm_notify && !mhi_drv->status_cb)
>> +			return -EINVAL;
>> +
>> +		/* For non-offload channels then xfer_cb should be provided */
>> +		if (!dl_chan->offload_ch && !mhi_drv->dl_xfer_cb)
>> +			return -EINVAL;
>> +
>> +		mhi_event = &mhi_cntrl->mhi_event[dl_chan->er_index];
>> +
>> +		/*
>> +		 * If the channel event ring is managed by client, then
>> +		 * status_cb must be provided so that the framework can
>> +		 * notify pending data
>> +		 */
>> +		if (mhi_event->cl_manage && !mhi_drv->status_cb)
>> +			return -EINVAL;
>> +
>> +		dl_chan->xfer_cb = mhi_drv->dl_xfer_cb;
>> +	}
>> +
>> +	/* Call the user provided probe function */
>> +	return mhi_drv->probe(mhi_dev, mhi_dev->id);
>> +}
>> +
>> +static int mhi_driver_remove(struct device *dev)
>> +{
>> +	struct mhi_device *mhi_dev = to_mhi_device(dev);
>> +	struct mhi_driver *mhi_drv = to_mhi_driver(dev->driver);
>> +	struct mhi_chan *mhi_chan;
>> +	enum mhi_ch_state ch_state[] = {
>> +		MHI_CH_STATE_DISABLED,
>> +		MHI_CH_STATE_DISABLED
>> +	};
>> +	int dir;
>> +
>> +	/* Skip if it is a controller device */
>> +	if (mhi_dev->dev_type == MHI_DEVICE_CONTROLLER)
>> +		return 0;
>> +
>> +	/* Reset both channels */
>> +	for (dir = 0; dir < 2; dir++) {
>> +		mhi_chan = dir ? mhi_dev->ul_chan : mhi_dev->dl_chan;
>> +
>> +		if (!mhi_chan)
>> +			continue;
>> +
>> +		/* Wake all threads waiting for completion */
>> +		write_lock_irq(&mhi_chan->lock);
>> +		mhi_chan->ccs = MHI_EV_CC_INVALID;
>> +		complete_all(&mhi_chan->completion);
>> +		write_unlock_irq(&mhi_chan->lock);
>> +
>> +		/* Set the channel state to disabled */
>> +		mutex_lock(&mhi_chan->mutex);
>> +		write_lock_irq(&mhi_chan->lock);
>> +		ch_state[dir] = mhi_chan->ch_state;
>> +		mhi_chan->ch_state = MHI_CH_STATE_SUSPENDED;
>> +		write_unlock_irq(&mhi_chan->lock);
>> +
>> +		mutex_unlock(&mhi_chan->mutex);
>> +	}
>> +
>> +	mhi_drv->remove(mhi_dev);
>> +
>> +	/* De-init channel if it was enabled */
>> +	for (dir = 0; dir < 2; dir++) {
>> +		mhi_chan = dir ? mhi_dev->ul_chan : mhi_dev->dl_chan;
>> +
>> +		if (!mhi_chan)
>> +			continue;
>> +
>> +		mutex_lock(&mhi_chan->mutex);
>> +
>> +		mhi_chan->ch_state = MHI_CH_STATE_DISABLED;
>> +
>> +		mutex_unlock(&mhi_chan->mutex);
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +int mhi_driver_register(struct mhi_driver *mhi_drv)
>> +{
>> +	struct device_driver *driver = &mhi_drv->driver;
>> +
>> +	if (!mhi_drv->probe || !mhi_drv->remove)
>> +		return -EINVAL;
>> +
>> +	driver->bus = &mhi_bus_type;
>> +	driver->probe = mhi_driver_probe;
>> +	driver->remove = mhi_driver_remove;
>> +
>> +	return driver_register(driver);
>> +}
>> +EXPORT_SYMBOL_GPL(mhi_driver_register);
> 
> You don't care about module owners of the driver?  Odd :(
> 
> (hint, you probably should...)
> 
> greg k-h
> 

For my own education, can you please clarify your comment?  I'm not sure 
that I understand the context of what you are saying (ie why is this 
export a possible problem?).

-- 
Jeffrey Hugo
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.