Patent Application
20060190653
1. Field of the Invention
This invention relates to computer systems, and more particularly, to portable computer systems that may be coupled to a docking station.
2. Description of the Related Art
Portable computers enjoy widespread popularity. Advances in computer technology, such as faster processors with low power consumption, have led to portable computer systems that are comparable to desktop computers in performance. Because of these improvements, portable computers are an ideal solution for a user that needs a large amount of computing power as well as a mobile platform.
Despite the performance increases, portable computers still are at a disadvantage relative to other computers. In particular, due to their small size, portable computers typically are not able to offer as much functionality as stationary computers, as a limited number of interfaces are present. One solution to this problem is a docking station. A docking station may allow for increased functionality when the portable computer is coupled to it. Through a docking station, a portable computer may be able to utilize the functionality of such devices as a full-screen monitor, additional printers, scanners, and so forth.
Although docking stations are a convenient solution to providing additional functionality for a portable computer, coupling the portable computer to a docking station may introduce a new set of issues that require attention. One such issue has arisen due to new industry requirements for security in computers, and specifically notebook computers using “LPC (Low Pin Count) Docking”. In many cases it may be required to protect information passing through a docking interface such that the information does not become accessible outside of the notebook computer.
Other corresponding issues related to the prior art will become apparent to one skilled in the art after comparing such prior art with the present invention as described herein.
A method and apparatus for operating a portable computer coupled to a docking station is disclosed. In one embodiment, the portable computer system includes a bus bridge and a bus coupled to the bus bridge. One or more peripheral devices or peripheral interfaces may be coupled to the bus. The bus may also be coupled to a docking interface. The docking interface may be an integrated circuit having a bus switch. The docking interface may be adapted to couple the bus to a peripheral interface in the docking station. When the bus switch is closed, after the computer is coupled to the docking station, the bus may be coupled to the peripheral interface, via a docking connector in the portable computer and a complementary connector in the docking station. The bus switch may close responsive to the docking, thereby completing the electrical coupling of the bus to the peripheral interface in the docking station. In one set of embodiments, the closing of the bus switch may be controlled by the docking interface such that operations on the bus are not suspended during docking operations.
In one embodiment, the bus may be a low pin count (LPC) bus. The bus switch may be a low on-resistance, high off-resistance bi-directional switch that may close to electrically couple the LPC bus to the docking connector. The docking station may include a complementary connector configured to be coupled to the docking connector of the portable computer. The complementary connector in the docking station may be electrically coupled to at least one peripheral interface. When the portable computer is connected to the docking station, a dock detect signal may be asserted and received by the docking interface. The docking interface may then initiate a sequence of events that result in the bus switch closing, thereby connecting the bus in the portable computer to the peripheral interface in the docking station. In one set of embodiments, the sequence of events that results in the closing of the bus switch may be performed without suspending operations on the bus.
In one set of embodiments, in order to support trusted LPC cycles, the bus switch may be configured to block trusted LPC cycles from being seen outside the docking interface during operation of the portable computers once the portable computer has been coupled to the docking station. The bus switch may comprise multiple switches, and once docking has been enabled, the switches may be closed. Subsequently, each LPC cycle may be tracked and a determination may be made at the beginning of each LPC cycle whether certain specified switches need to be opened or need to remain closed. In one embodiment, the start of a trusted LPC cycle is recognized upon receiving a special code indicative of a trusted LPC cycle, and after having ascertained that the LPC cycle is a trusted LPC cycle certain specified switches are opened. The specified switches may then be closed at the end of each trusted LPC cycle, or any time a trusted LPC cycle is aborted. In some embodiments, a trusted LPC cycle may be aborted by receiving a new information packet/frame prior to the trusted LPC cycle completing.
It should be noted that bus types other than the LPC bus are possible and contemplated for the method and apparatus described herein. Other types of buses may include, but are not limited to, a peripheral component interconnect (PCI) bus, an industry standard architecture or extended industry standard architecture (ISA/EISA) bus, universal serial bus (USB), general purpose instrument bus (GPIB), advanced graphics port (AGP), and so forth.
Other aspects of the invention will become apparent upon reading the following detailed description and upon reference to the accompanying drawings in which:
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and description thereto are not intended to limit the invention to the particular form disclosed, but, on the contrary, the invention is to cover all modifications, equivalents, and alternatives falling with the spirit and scope of the present invention as defined by the appended claims.
The Intel® LPC Interface Specification, Revision 1.0, Sep. 29, 1997, is incorporated by reference herein in its entirety.
U.S. patent application Ser. No. 10/076,105 titled “Switched Hot Docking Interface” invented by Richard Boz, Ronald Streiber, John Virzi and Richard Wahler, and filed on Feb. 14, 2002, is hereby incorporated by reference in its entirety as though fully and completely set forth herein.
Docking station 120 may provide additional functionality to portable computer 100. Docking station 120 may include connections for a full-size keyboard, a monitor, a printer, and various other peripheral devices. Docking station may be able to provide the use of a full-size keyboard and monitor display when portable computer 100 is coupled to docking station 120. Various types of peripheral bus interfaces may be employed, including universal serial bus (USB), peripheral component interconnect (PCI), and/or similar bus interfaces well known in the art. Through the various interfaces in both portable computer 100 and docking station 120, the use of various devices such as flatbed and feed-through scanners, high capacity disk drives (e.g. a ZIP drive or external USB hard drive), network interfaces, printers, joysticks, a trackball or mouse, and many other devices may be employed. Although portable computer 100 may include some of the same types of interfaces as docking station 120, the docking station may provide additional interfaces, thereby expanding the functionality of the portable computer.
In one set of embodiments, portable computer 100 may also be configured for hot-docking to docking station 120. In other embodiments hot-docking may not be a requirement and power may be interrupted prior to docking portable computer 100 to docking station 120. Hot-docking may be defined here as coupling portable computer 100 to docking station 120 without an interruption in power when the computer is not in suspend mode or hibernation mode. In the embodiment shown, it may be unnecessary to power down or suspend power to portable computer 100 when coupling it to docking station 120. Furthermore, portable computer 100 may be configured to continue operations without interruption during hot-docking operations. Continuing operations may include transactions on a bus configured to electrically couple to docking station 120 as a result of hot-docking operations. Thus, operations on a bus in portable computer 100 may continue uninterrupted even while the bus is electrically coupled to docking station 120.
In one set of embodiments, portable computer 100 may be further configured to be undocked from docking station 120 without removing power. Bus transactions within portable computer 100 may continue uninterrupted during undocking operations, even after communications with docking station 120 have been terminated. Docking station 120 may be powered down responsive to the undocking.
Turning now to
Bus 103 may also be coupled to peripheral interfaces 110 and 112. Peripheral interfaces may allow devices to be coupled to portable computer 100, and in some cases, may be devices that are actual components of portable computer 100. Such devices may include, but are not limited to, disk drives, modems, network interfaces, Universal Asynchronous Receiver-Transmitters (UARTs), Parallel Ports, Floppy Disk, and similar peripherals well known in the art. Bus 103 may allow peripheral interfaces 110 and 112 to communicate with a processor (not shown) and a memory system (not shown) in portable computer 100. It should be noted that the portion of the bus that is actually coupled to the docking station (to the right of the switch in the drawing) may be referred to as a switched bus.
Computer system 100 also includes clock driver 106. Clock driver 106 may be coupled to bus bridge 104 by utility bus 109. Bus bridge 104 may send commands over utility bus 109 to clock driver 106 to enable or disable the clock driver outputs. In the embodiment shown, clock driver 106 has two clock outputs, one for driving a clock signal to docking interface 102 and one for driving a clock signal to docking station 120. Additional clock outputs for driving clock signals to other devices in portable computer system may also be present.
Portable computer 100 may include docking connector 114, which may be configured to couple to complementary connector 121 in docking station 120. When coupled together, docking connector 114 and complementary connector 121 may provide physical and electrical connections between portable computer 100 and docking station 120. At least one signal path through docking connector 114 may be configured to provide a dock detect signal to docking interface 102. In the embodiment shown, the dock detect signal is asserted in a logic low state. The dock detect signal may normally be pulled to a logic high state by resistor 118, which may be coupled to a power node in portable computer 100. When docking portable computer 100 to docking station 120, the signal line associated with the dock detect signal may be coupled to a ground node, thereby causing the dock detect signal to be asserted in a logic low state. Other embodiments are possible and contemplated wherein the dock detect signal is asserted in a logic high state, and/or wherein a pull-up or pull down resistor is configured in docking station 120.
Docking connector 114 may also include power pin 113. In some embodiments, docking station 120 may be configured to receive power from portable computer 100. In the embodiment shown, power pin 113 provides a path for power from a power node of portable computer 100 to docking station 120. In some embodiments, multiple power pins may be present, as well as corresponding multiple ground pins. In other embodiments, docking station 120 may receive power from an external source separate from portable computer 100. In such embodiments, power pin 113 may be used to convey a signal to initiate a power-up sequence in docking station 120. Additional embodiments are possible and contemplated wherein the mere act of coupling portable computer 100 to docking station 120 causes power-up sequence to be executed in docking station 120. The power-up sequence may turn on power received from portable computer 100, or power received from another external source.
As previously noted, docking interface 102 may be configured to receive a dock detect signal. When docking interface 102 detects an assertion of the dock detect signal, it may begin operations to electrically couple bus 103 to peripheral interface chip 122 in docking station 120. In the embodiment shown, peripheral interface chip 122 is a single chip with multiple interfaces. Other embodiments are possible and contemplated wherein multiple interface chips are present (and configured to couple to bus 103 when portable computer 100 is docked to docking station 120). Furthermore, such interface chips may include a single interface or multiple interfaces. In the embodiment shown, peripheral interface chip 122 includes serial port 124 and parallel port 126. Serial port 124 is shown here coupling to peripheral device 132, while parallel port 126 is shown here coupling to peripheral device 130.
Docking interface 102 may include bus switch 107 coupled to bus 103, and switch control circuit 117 and cycle monitoring circuit 119 both coupled to bus 103 on one side of bus switch 107. In one embodiment, bus switch 107 is a low on-resistance, high off-resistance bi-directional switch. Bus switch 107 may also be configured to comprise multiple individual switches. Switch control circuit 117 may include a translation circuit for translating various bus commands into open and close commands for bus switch 107. In one embodiment, switch control circuit 117 may receive ‘write’ commands via bus 103. The translation circuit in switch control circuit 117 may translate these commands to an ‘open’ or ‘close’ command. Switch control circuit 117 may open or close bus switch 107 depending upon the command received. In one embodiment, cycle monitoring circuit 119 is configured to monitor bus cycles that occur on bus 103, and determine whether a given bus cycle is a trusted bus cycle. As used herein, a ‘trusted bus cycle’ refers to a bus cycle wherein information transmitted during the bus cycle is to be protected and is not to be made available outside the portable computer. However, a trusted bus cycle may also be defined as any special bus cycle that is to be treated differently from regular bus cycles, and other designations for trusted bus cycles are possible and are contemplated. Cycle monitoring circuit 119 may further be configured to provide a signal indicative of a trusted bus cycle to bus switch 107 if a bus cycle has been determined to be a trusted bus cycle. In one set of embodiments, cycle monitoring circuit 119 may operate in conjunction with switch control circuit 117 to open or close bus switch 107 depending upon the command received, and whether the command is part of a trusted bus cycle.
When docking interface 102 detects an assertion of the dock detect signal, it may initiate a sequence of events that result in the closing of bus switch 107. This sequence of events may include docking interface 102 communicating with bus bridge 104 to indicate that computer system 100 is coupled to docking station 120. Such communication may be performed over bus 103, or, in other embodiments, over separate signal lines that couple docking interface 102 to bus bridge 104. Bus bridge 104 may respond by forwarding one or more commands to the translations circuit within switch control circuit 117. These commands may be translated and may cause switch control circuit 117 to close bus switch 107. The commands may include timing and/or other information that allows the closing of bus switch 107 to be precisely timed. In order to ensure the proper timing, clock driver circuit 106 may begin driving a clock signal to docking station 120. This may allow for proper synchronization of transactions occurring between portable computer 100 and docking station 120 following the closing of bus switch 107 and subsequent utilization of docking station peripherals by portable computer 100. The closing of bus switch 107 may be performed in such a manner as to prevent or minimize electrical transients on bus 103. Precise control of the closing of bus switch 107 by switch control circuit 117 may allow the switch to be closed without any significant disturbance to current traffic on bus 103 (e.g. a transaction between bus bridge 104 and peripheral interface 110). In embodiments where bus cycles are monitored, cycle monitoring circuit 119 may operate in conjunction with switch control circuit 117 to open and/or close portions of the switches comprised in bus switch 107, depending on whether a bus cycle is a trusted bus cycle.
When bus switch 107 is closed, bus 103 may be electrically coupled to peripheral interface chip 122 in docking station 120. This may allow portable computer 100 to take advantage of the extra functionality provided by docking station 120. With bus switch 107 closed, bus bridge 104 may have a communications link to peripheral interface chip 122, and hence any peripheral devices coupled to it (e.g. peripheral devices 130 and 132).
Docking interface 102 may be further configured to initiate undocking procedures when it is desired to undock portable computer 100 from docking station 120. The initiation of undocking procedures may be a result of an input from a user of portable computer 100. For example, a user may select an “eject” option from a start menu of an operating system running on computer 100. This may eventually cause commands to be sent to the translation circuit in switch control circuit 117. Pending transactions between docking station 120 and portable computer 100 may be allowed to complete in some instances, or may be terminated in other instances. Once all transactions have been completed or terminated, switch control circuit 117 may open bus switch 107, thereby disconnecting bus 103 from peripheral interface 122 in docking station 120. It should be noted that the timing of events related to opening bus switch 107 may be similar or identical to the timing necessary for closing the switch.
Moving now to
In the embodiment of the method shown, a portable computer is physically coupled to the docking station (202). The physical coupling of a portable computer to a docking station may comprise the coupling of a connector on the portable computer to a complementary connector on a docking station. This may provide the physical/electrical connections that are necessary in order for the portable computer to utilize the extra functionality provided by the docking station. When the portable computer system is coupled to the docking station, a dock detect signal may be asserted (204). The dock detect signal may be received by the portable computer. In one embodiment, the dock detect signal may be received by a docking interface such as docking interface 102 of
Following the assertion and detection of the dock detect signal, a power up sequence in the docking station may be initiated (206). The power up sequence may include the portable computer supplying power to the docking station in some embodiments, while other embodiments may include the docking station receiving power from another external source. It should be noted that, in some embodiments, the docking station may be powered up prior to docking, and thus no power up sequence may be necessary. When the docking station is fully powered up, it may assert a signal to indicate that it has been powered up successfully (i.e. a ‘power ok’ signal). The signal may be received by the portable computer, which may begin other operations in order to initialize bus connections with the docking station, thereby allowing the portable computer to utilize additional peripheral functions.
Initializing bus connections between the portable computer and the docking station may include sending commands to a switch control circuit (208). Using the example shown in
As previously noted, in one embodiment, the bus may be an LPC bus. The LPC bus may include a ‘turnaround’ phase, or cycle. The turnaround cycle, in one embodiment, may be two system clock cycles in width, and may be initiated when the bus bridge is turning control of the bus over to a peripheral device, or when the peripheral device is returning control of the bus to the bus bridge. During a write cycle to the translation circuit, which may be implemented as a register in one embodiment, two turnaround cycles may occur. The first turnaround cycle may occur when a command is written to the register. At the beginning of the second turnaround cycle, as control of the bus is returned to the bus bridge, the switch may close, thereby electrically coupling the bus to the peripheral interface in the docking station.
Once the bus switch has been closed, the portable computer may begin operations with the docking station (212). More particularly, the bus may be used to communicate with peripherals in the portable computer and peripherals in the docking station. Thus, the portable computer may utilize extra functionality provided by the docking station. As previously noted, alternative methods to method 200 for docking the portable computer to the docking station are possible and are contemplated.
Moving now to
In the embodiment shown in
For the embodiments of both
Considering the timing diagrams of
Considering again the timing diagrams of
While the present invention has been described with reference to particular embodiments, it will be understood that the embodiments are illustrative and that the invention scope is not so limited. Any variations, modifications, additions, and improvements to the embodiments described are possible. These variations, modifications, additions, and improvements may fall within the scope of the inventions as detailed within the following claims.
