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Diffstat (limited to 'Documentation/DocBook')
| -rw-r--r-- | Documentation/DocBook/libata.tmpl | 156 |
1 files changed, 124 insertions, 32 deletions
diff --git a/Documentation/DocBook/libata.tmpl b/Documentation/DocBook/libata.tmpl index cf2fce7..6df1dfd 100644 --- a/Documentation/DocBook/libata.tmpl +++ b/Documentation/DocBook/libata.tmpl @@ -14,7 +14,7 @@ </authorgroup> <copyright> - <year>2003</year> + <year>2003-2005</year> <holder>Jeff Garzik</holder> </copyright> @@ -44,30 +44,38 @@ <toc></toc> - <chapter id="libataThanks"> - <title>Thanks</title> + <chapter id="libataIntroduction"> + <title>Introduction</title> <para> - The bulk of the ATA knowledge comes thanks to long conversations with - Andre Hedrick (www.linux-ide.org). + 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> - 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). + 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> @@ -78,6 +86,9 @@ void (*port_disable) (struct ata_port *); unplug). </para> + </sect2> + + <sect2><title>Post-IDENTIFY device configuration</title> <programlisting> void (*dev_config) (struct ata_port *, struct ata_device *); </programlisting> @@ -88,6 +99,9 @@ void (*dev_config) (struct ata_port *, struct ata_device *); 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 *); @@ -108,6 +122,9 @@ void (*post_set_mode) (struct ata_port *ap); ->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); @@ -120,6 +137,9 @@ 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> @@ -129,17 +149,37 @@ void (*exec_command)(struct ata_port *ap, struct ata_taskfile *tf); ->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> @@ -147,9 +187,13 @@ void (*dev_select)(struct ata_port *ap, unsigned int device); <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> @@ -162,17 +206,31 @@ void (*phy_reset) (struct ata_port *ap); 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. +When setting up an IDE BMDMA transaction, these hooks arm +(->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); @@ -190,20 +248,26 @@ 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. +This is a high level error handling function, called from the +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 *); @@ -216,6 +280,9 @@ 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, @@ -227,6 +294,9 @@ 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); @@ -240,15 +310,17 @@ void (*host_stop) (struct ata_host_set *host_set); 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> @@ -279,4 +351,24 @@ void (*host_stop) (struct ata_host_set *host_set); !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> |