将参数添加到char设备

Question

我正在编写一个字符设备，它将获得进程pid并返回父进程ID，开始时间和兄弟节点数。我正在使用此网站：http://tldp.org/LDP/lkmpg/2.6/html/x892.html#AEN972作为指南。 我想在字符驱动程序的read调用中添加一个参数，但它不允许我这样做。我的代码如下所示：

public class MainActivity extends AppWidgetProvider {

    private XYMultipleSeriesDataset mDataset = getDemoDataset();
    private XYMultipleSeriesRenderer mRenderer = getDemoRenderer();
    private GraphicalView mChartView;

    @SuppressLint("NewApi")
    @SuppressWarnings("deprecation")
    @Override
    public void onUpdate(Context context, AppWidgetManager appWidgetManager,
            int[] appWidgetIds) {

        for (int i = 0; i < appWidgetIds.length; i++) {

            int currentWidgetId = appWidgetIds[i];

            RemoteViews views = new RemoteViews(context.getPackageName(),
                    R.layout.activity_main);

            setRendererStyling();

            if (mChartView == null) {

                LayoutInflater inflater = LayoutInflater.from(context);
                View rowView = inflater.inflate(R.layout.second, null, true);

                LinearLayout layout = (LinearLayout) rowView
                        .findViewById(R.id.chart);

                mChartView = ChartFactory.getLineChartView(context, mDataset,
                        mRenderer);

                mRenderer.setSelectableBuffer(100);

                layout.addView(mChartView, new LayoutParams(
                        LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));

                // views.apply(context, layout);

                views.setImageViewBitmap(R.id.img_view,
                        layout.getDrawingCache());

                appWidgetManager.updateAppWidget(currentWidgetId, views);
                Toast.makeText(context, "widget added", Toast.LENGTH_SHORT)
                        .show();

            } else {
                mChartView.repaint();
            }

        }
    }
}