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Writing Device Drivers     Oracle Solaris 11 Information Library
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Part I Designing Device Drivers for the Oracle Solaris Platform

1.  Overview of Oracle Solaris Device Drivers

Device Driver Basics

What Is a Device Driver?

What Is a Device Driver Entry Point?

Device Driver Entry Points

Entry Points Common to All Drivers

Device Access Entry Points

Loadable Module Entry Points

Autoconfiguration Entry Points

Kernel Statistics Entry Points

Power Management Entry Point

System Quiesce Entry Point

Summary of Common Entry Points

Entry Points for Block Device Drivers

Entry Points for Character Device Drivers

Entry Points for STREAMS Device Drivers

Entry Points for Memory Mapped Devices

Entry Points for Network Device Drivers

Entry Points for SCSI HBA Drivers

Entry Points for PC Card Drivers

Considerations in Device Driver Design

DDI/DKI Facilities

Device IDs

Device Properties

Interrupt Handling

Callback Functions

Software State Management

Programmed I/O Device Access

Direct Memory Access (DMA)

Layered Driver Interfaces

Driver Context

Returning Errors

Dynamic Memory Allocation


2.  Oracle Solaris Kernel and Device Tree

3.  Multithreading

4.  Properties

5.  Managing Events and Queueing Tasks

6.  Driver Autoconfiguration

7.  Device Access: Programmed I/O

8.  Interrupt Handlers

9.  Direct Memory Access (DMA)

10.  Mapping Device and Kernel Memory

11.  Device Context Management

12.  Power Management

13.  Hardening Oracle Solaris Drivers

14.  Layered Driver Interface (LDI)

Part II Designing Specific Kinds of Device Drivers

15.  Drivers for Character Devices

16.  Drivers for Block Devices

17.  SCSI Target Drivers

18.  SCSI Host Bus Adapter Drivers

19.  Drivers for Network Devices

20.  USB Drivers

21.  SR-IOV Drivers

Part III Building a Device Driver

22.  Compiling, Loading, Packaging, and Testing Drivers

23.  Debugging, Testing, and Tuning Device Drivers

24.  Recommended Coding Practices

Part IV Appendixes

A.  Hardware Overview

B.  Summary of Oracle Solaris DDI/DKI Services

C.  Making a Device Driver 64-Bit Ready

D.  Console Frame Buffer Drivers

E.  pci.conf File


Device Driver Basics

This section introduces you to device drivers and their entry points on the Oracle Solaris platform.

What Is a Device Driver?

A device driver is a kernel module that is responsible for managing the low-level I/O operations of a hardware device. Device drivers are written with standard interfaces that the kernel can call to interface with a device. Device drivers can also be software-only, emulating a device that exists only in software, such as RAM disks, buses, and pseudo-terminals.

A device driver contains all the device-specific code necessary to communicate with a device. This code includes a standard set of interfaces to the rest of the system. This interface shields the kernel from device specifics just as the system call interface protects application programs from platform specifics. Application programs and the rest of the kernel need little, if any, device-specific code to address the device. In this way, device drivers make the system more portable and easier to maintain.

When the Oracle Solaris operating system (Oracle Solaris OS) is initialized, devices identify themselves and are organized into the device tree, a hierarchy of devices. In effect, the device tree is a hardware model for the kernel. An individual device driver is represented as a node in the tree with no children. This type of node is referred to as a leaf driver. A driver that provides services to other drivers is called a bus nexus driver and is shown as a node with children. As part of the boot process, physical devices are mapped to drivers in the tree so that the drivers can be located when needed. For more information on how the Oracle Solaris OS accommodates devices, see Chapter 2, Oracle Solaris Kernel and Device Tree.

Device drivers are classified by how they handle I/O. Device drivers fall into three broad categories:

What Is a Device Driver Entry Point?

An entry point is a function within a device driver that can be called by an external entity to get access to some driver functionality or to operate a device. Each device driver provides a standard set of functions as entry points. For the complete list of entry points for all driver types, see the Intro(9E) man page. The Oracle Solaris kernel uses entry points for these general task areas:

Drivers for different types of devices have different sets of entry points according to the kinds of operations the devices perform. A driver for a memory-mapped character-oriented device, for example, supports a devmap(9E) entry point, while a block driver does not support this entry.

Use a prefix based on the name of your driver to give driver functions unique names. Typically, this prefix is the name of the driver, such as xx_open() for the open(9E) routine of driver xx. See Use a Unique Prefix to Avoid Kernel Symbol Collisions for more information. In subsequent examples in this book, xx is used as the driver prefix.