Automatic merge with /usr/src/ntfs-2.6.git

  </authorgroup>

  <copyright>

   <year>2003</year>

   <year>2003-2005</year>

   <holder>Jeff Garzik</holder>

  </copyright>

<toc></toc>

  <chapter id="libataThanks">

     <title>Thanks</title>

  <para>

  The bulk of the ATA knowledge comes thanks to long conversations with

  Andre Hedrick (www.linux-ide.org).

  </para>

  <chapter id="libataIntroduction">

     <title>Introduction</title>

  <para>

  Thanks to Alan Cox for pointing out similarities 

  between SATA and SCSI, and in general for motivation to hack on

  libata.

  libATA is a library used inside the Linux kernel to support ATA host

  controllers and devices.  libATA provides an ATA driver API, class

  transports for ATA and ATAPI devices, and SCSI<->ATA translation

  for ATA devices according to the T10 SAT specification.

  </para>

  <para>

  libata's device detection

  method, ata_pio_devchk, and in general all the early probing was

  based on extensive study of Hale Landis's probe/reset code in his

  ATADRVR driver (www.ata-atapi.com).

  This Guide documents the libATA driver API, library functions, library

  internals, and a couple sample ATA low-level drivers.

  </para>

  </chapter>

  <chapter id="libataDriverApi">

     <title>libata Driver API</title>

     <para>

     struct ata_port_operations is defined for every low-level libata

     hardware driver, and it controls how the low-level driver

     interfaces with the ATA and SCSI layers.

     </para>

     <para>

     FIS-based drivers will hook into the system with ->qc_prep() and

     ->qc_issue() high-level hooks.  Hardware which behaves in a manner

     similar to PCI IDE hardware may utilize several generic helpers,

     defining at a bare minimum the bus I/O addresses of the ATA shadow

     register blocks.

     </para>

     <sect1>

        <title>struct ata_port_operations</title>

	<sect2><title>Disable ATA port</title>

	<programlisting>

void (*port_disable) (struct ata_port *);

	</programlisting>

	unplug).

	</para>

	</sect2>

	<sect2><title>Post-IDENTIFY device configuration</title>

	<programlisting>

void (*dev_config) (struct ata_port *, struct ata_device *);

	</programlisting>

	issue of SET FEATURES - XFER MODE, and prior to operation.

	</para>

	</sect2>

	<sect2><title>Set PIO/DMA mode</title>

	<programlisting>

void (*set_piomode) (struct ata_port *, struct ata_device *);

void (*set_dmamode) (struct ata_port *, struct ata_device *);

	->set_dma_mode() is only called if DMA is possible.

	</para>

	</sect2>

	<sect2><title>Taskfile read/write</title>

	<programlisting>

void (*tf_load) (struct ata_port *ap, struct ata_taskfile *tf);

void (*tf_read) (struct ata_port *ap, struct ata_taskfile *tf);

	taskfile register values.

	</para>

	</sect2>

	<sect2><title>ATA command execute</title>

	<programlisting>

void (*exec_command)(struct ata_port *ap, struct ata_taskfile *tf);

	</programlisting>

	->tf_load(), to be initiated in hardware.

	</para>

	</sect2>

	<sect2><title>Per-cmd ATAPI DMA capabilities filter</title>

	<programlisting>

int (*check_atapi_dma) (struct ata_queued_cmd *qc);

	</programlisting>

	<para>

Allow low-level driver to filter ATA PACKET commands, returning a status

indicating whether or not it is OK to use DMA for the supplied PACKET

command.

	</para>

	</sect2>

	<sect2><title>Read specific ATA shadow registers</title>

	<programlisting>

u8   (*check_status)(struct ata_port *ap);

void (*dev_select)(struct ata_port *ap, unsigned int device);

u8   (*check_altstatus)(struct ata_port *ap);

u8   (*check_err)(struct ata_port *ap);

	</programlisting>

	<para>

	Reads the Status ATA shadow register from hardware.  On some

	hardware, this has the side effect of clearing the interrupt

	condition.

	Reads the Status/AltStatus/Error ATA shadow register from

	hardware.  On some hardware, reading the Status register has

	the side effect of clearing the interrupt condition.

	</para>

	</sect2>

	<sect2><title>Select ATA device on bus</title>

	<programlisting>

void (*dev_select)(struct ata_port *ap, unsigned int device);

	</programlisting>

	<para>

	Issues the low-level hardware command(s) that causes one of N

	hardware devices to be considered 'selected' (active and

	available for use) on the ATA bus.

	available for use) on the ATA bus.  This generally has no

meaning on FIS-based devices.

	</para>

	</sect2>

	<sect2><title>Reset ATA bus</title>

	<programlisting>

void (*phy_reset) (struct ata_port *ap);

	</programlisting>

	functions ata_bus_reset() or sata_phy_reset() for this hook.

	</para>

	</sect2>

	<sect2><title>Control PCI IDE BMDMA engine</title>

	<programlisting>

void (*bmdma_setup) (struct ata_queued_cmd *qc);

void (*bmdma_start) (struct ata_queued_cmd *qc);

void (*bmdma_stop) (struct ata_port *ap);

u8   (*bmdma_status) (struct ata_port *ap);

	</programlisting>

	<para>

When setting up an IDE BMDMA transaction, these hooks arm

	(->bmdma_setup) and fire (->bmdma_start) the hardware's DMA

	engine.

(->bmdma_setup), fire (->bmdma_start), and halt (->bmdma_stop)

the hardware's DMA engine.  ->bmdma_status is used to read the standard

PCI IDE DMA Status register.

	</para>

	<para>

These hooks are typically either no-ops, or simply not implemented, in

FIS-based drivers.

	</para>

	</sect2>

	<sect2><title>High-level taskfile hooks</title>

	<programlisting>

void (*qc_prep) (struct ata_queued_cmd *qc);

int (*qc_issue) (struct ata_queued_cmd *qc);

	->qc_issue is used to make a command active, once the hardware

	and S/G tables have been prepared.  IDE BMDMA drivers use the

	helper function ata_qc_issue_prot() for taskfile protocol-based

	dispatch.  More advanced drivers roll their own ->qc_issue

	implementation, using this as the "issue new ATA command to

	hardware" hook.

	dispatch.  More advanced drivers implement their own ->qc_issue.

	</para>

	</sect2>

	<sect2><title>Timeout (error) handling</title>

	<programlisting>

void (*eng_timeout) (struct ata_port *ap);

	</programlisting>

	<para>

This is a high level error handling function, called from the

	error handling thread, when a command times out.

error handling thread, when a command times out.  Most newer

hardware will implement its own error handling code here.  IDE BMDMA

drivers may use the helper function ata_eng_timeout().

	</para>

	</sect2>

	<sect2><title>Hardware interrupt handling</title>

	<programlisting>

irqreturn_t (*irq_handler)(int, void *, struct pt_regs *);

void (*irq_clear) (struct ata_port *);

	is quiet.

	</para>

	</sect2>

	<sect2><title>SATA phy read/write</title>

	<programlisting>

u32 (*scr_read) (struct ata_port *ap, unsigned int sc_reg);

void (*scr_write) (struct ata_port *ap, unsigned int sc_reg,

	if ->phy_reset hook called the sata_phy_reset() helper function.

	</para>

	</sect2>

	<sect2><title>Init and shutdown</title>

	<programlisting>

int (*port_start) (struct ata_port *ap);

void (*port_stop) (struct ata_port *ap);

	tasks.  

	</para>

	<para>

	->host_stop() is called when the rmmod or hot unplug process

	begins.  The hook must stop all hardware interrupts, DMA

	engines, etc.

	</para>

	<para>

	->port_stop() is called after ->host_stop().  It's sole function

	is to release DMA/memory resources, now that they are no longer

	actively being used.

	</para>

	<para>

	->host_stop() is called after all ->port_stop() calls

have completed.  The hook must finalize hardware shutdown, release DMA

and other resources, etc.

	</para>

	</sect2>

     </sect1>

  </chapter>

!Idrivers/scsi/sata_sil.c

  </chapter>

  <chapter id="libataThanks">

     <title>Thanks</title>

  <para>

  The bulk of the ATA knowledge comes thanks to long conversations with

  Andre Hedrick (www.linux-ide.org), and long hours pondering the ATA

  and SCSI specifications.

  </para>

  <para>

  Thanks to Alan Cox for pointing out similarities 

  between SATA and SCSI, and in general for motivation to hack on

  libata.

  </para>

  <para>

  libata's device detection

  method, ata_pio_devchk, and in general all the early probing was

  based on extensive study of Hale Landis's probe/reset code in his

  ATADRVR driver (www.ata-atapi.com).

  </para>

  </chapter>

</book>

     CPU frequency and voltage scaling statictics in the Linux(TM) kernel

             L i n u x    c p u f r e q - s t a t s   d r i v e r

                       - information for users -

             Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>

Contents

1. Introduction

2. Statistics Provided (with example)

3. Configuring cpufreq-stats

1. Introduction

cpufreq-stats is a driver that provices CPU frequency statistics for each CPU.

This statistics is provided in /sysfs as a bunch of read_only interfaces. This

interface (when configured) will appear in a seperate directory under cpufreq

in /sysfs (<sysfs root>/devices/system/cpu/cpuX/cpufreq/stats/) for each CPU.

Various statistics will form read_only files under this directory.

This driver is designed to be independent of any particular cpufreq_driver

that may be running on your CPU. So, it will work with any cpufreq_driver.

2. Statistics Provided (with example)

cpufreq stats provides following statistics (explained in detail below).

-  time_in_state

-  total_trans

-  trans_table

All the statistics will be from the time the stats driver has been inserted 

to the time when a read of a particular statistic is done. Obviously, stats 

driver will not have any information about the the frequcny transitions before

the stats driver insertion.

--------------------------------------------------------------------------------

<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # ls -l

total 0

drwxr-xr-x  2 root root    0 May 14 16:06 .

drwxr-xr-x  3 root root    0 May 14 15:58 ..

-r--r--r--  1 root root 4096 May 14 16:06 time_in_state

-r--r--r--  1 root root 4096 May 14 16:06 total_trans

-r--r--r--  1 root root 4096 May 14 16:06 trans_table

--------------------------------------------------------------------------------

-  time_in_state

This gives the amount of time spent in each of the frequencies supported by

this CPU. The cat output will have "<frequency> <time>" pair in each line, which

will mean this CPU spent <time> usertime units of time at <frequency>. Output

will have one line for each of the supported freuencies. usertime units here 

is 10mS (similar to other time exported in /proc).

--------------------------------------------------------------------------------

<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat time_in_state 

3600000 2089

3400000 136

3200000 34

3000000 67

2800000 172488

--------------------------------------------------------------------------------

-  total_trans

This gives the total number of frequency transitions on this CPU. The cat 

output will have a single count which is the total number of frequency

transitions.

--------------------------------------------------------------------------------

<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat total_trans

20

--------------------------------------------------------------------------------

-  trans_table

This will give a fine grained information about all the CPU frequency

transitions. The cat output here is a two dimensional matrix, where an entry

<i,j> (row i, column j) represents the count of number of transitions from 

Freq_i to Freq_j. Freq_i is in descending order with increasing rows and 

Freq_j is in descending order with increasing columns. The output here also 

contains the actual freq values for each row and column for better readability.

--------------------------------------------------------------------------------

<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat trans_table

   From  :    To

         :   3600000   3400000   3200000   3000000   2800000 

  3600000:         0         5         0         0         0 

  3400000:         4         0         2         0         0 

  3200000:         0         1         0         2         0 

  3000000:         0         0         1         0         3 

  2800000:         0         0         0         2         0 

--------------------------------------------------------------------------------

3. Configuring cpufreq-stats

To configure cpufreq-stats in your kernel

Config Main Menu

	Power management options (ACPI, APM)  --->

		CPU Frequency scaling  --->

			[*] CPU Frequency scaling

			<*>   CPU frequency translation statistics 

			[*]     CPU frequency translation statistics details

"CPU Frequency scaling" (CONFIG_CPU_FREQ) should be enabled to configure

cpufreq-stats.

"CPU frequency translation statistics" (CONFIG_CPU_FREQ_STAT) provides the

basic statistics which includes time_in_state and total_trans.

"CPU frequency translation statistics details" (CONFIG_CPU_FREQ_STAT_DETAILS)

provides fine grained cpufreq stats by trans_table. The reason for having a

seperate config option for trans_table is:

- trans_table goes against the traditional /sysfs rule of one value per

  interface. It provides a whole bunch of value in a 2 dimensional matrix

  form.

Once these two options are enabled and your CPU supports cpufrequency, you

will be able to see the CPU frequency statistics in /sysfs.

W:	http://www.linux-usb.org/SpeedTouch/

S:	Maintained

ALI1563 I2C DRIVER

P:	Rudolf Marek

M:	r.marek@sh.cvut.cz

L:	sensors@stimpy.netroedge.com

S:	Maintained

ALPHA PORT

P:	Richard Henderson

M:	rth@twiddle.net

S:	Maintained

SN-IA64 (Itanium) SUB-PLATFORM

P:	Jesse Barnes

M:	jbarnes@sgi.com

P:	Greg Edwards

M:	edwardsg@sgi.com

L:	linux-altix@sgi.com

L:	linux-ia64@vger.kernel.org

W:	http://www.sgi.com/altix

VERSION = 2

PATCHLEVEL = 6

SUBLEVEL = 12

EXTRAVERSION =-rc5

EXTRAVERSION =-rc6

NAME=Woozy Numbat

# *DOCUMENTATION*

void default_idle(void)

{

	while(1) {

		if (need_resched()) {

		if (!need_resched()) {

			local_irq_enable();

			__asm__("sleep");

			local_irq_disable();