mirror of https://gitee.com/openkylin/linux.git
libata: Fix several inaccuracies in developer's guide
Commit6bfff31e77
(libata: kill probe_ent and related helpers) killed ata_device_add() but didn't remove references to it from the libata developer's guide. Commits9363c3825e
(libata: rename SFF functions) and5682ed33aa
(libata: rename SFF port ops) renamed the taskfile access methods but didn't update the developer's guide. Commitc9f75b04ed
(libata: kill ata_noop_dev_select()) didn't update the developer's guide as well. The guide also refers to the long gone ata_pio_data_xfer_noirq(), ata_pio_data_xfer(), and ata_mmio_data_xfer() -- replace those by the modern ata_sff_data_xfer_noirq(), ata_sff_data_xfer(), and ata_sff_data_xfer32(). Also, remove the reference to non-existant ata_port_stop()... Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com> Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
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@ -107,10 +107,6 @@ void (*dev_config) (struct ata_port *, struct ata_device *);
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issue of SET FEATURES - XFER MODE, and prior to operation.
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</para>
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<para>
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Called by ata_device_add() after ata_dev_identify() determines
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a device is present.
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</para>
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<para>
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This entry may be specified as NULL in ata_port_operations.
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</para>
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@ -154,8 +150,8 @@ unsigned int (*mode_filter) (struct ata_port *, struct ata_device *, unsigned in
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<sect2><title>Taskfile read/write</title>
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<programlisting>
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void (*tf_load) (struct ata_port *ap, struct ata_taskfile *tf);
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void (*tf_read) (struct ata_port *ap, struct ata_taskfile *tf);
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void (*sff_tf_load) (struct ata_port *ap, struct ata_taskfile *tf);
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void (*sff_tf_read) (struct ata_port *ap, struct ata_taskfile *tf);
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</programlisting>
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<para>
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@ -164,36 +160,35 @@ void (*tf_read) (struct ata_port *ap, struct ata_taskfile *tf);
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hardware registers / DMA buffers, to obtain the current set of
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taskfile register values.
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Most drivers for taskfile-based hardware (PIO or MMIO) use
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ata_tf_load() and ata_tf_read() for these hooks.
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ata_sff_tf_load() and ata_sff_tf_read() for these hooks.
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</para>
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</sect2>
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<sect2><title>PIO data read/write</title>
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<programlisting>
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void (*data_xfer) (struct ata_device *, unsigned char *, unsigned int, int);
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void (*sff_data_xfer) (struct ata_device *, unsigned char *, unsigned int, int);
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</programlisting>
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<para>
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All bmdma-style drivers must implement this hook. This is the low-level
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operation that actually copies the data bytes during a PIO data
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transfer.
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Typically the driver
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will choose one of ata_pio_data_xfer_noirq(), ata_pio_data_xfer(), or
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ata_mmio_data_xfer().
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Typically the driver will choose one of ata_sff_data_xfer_noirq(),
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ata_sff_data_xfer(), or ata_sff_data_xfer32().
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</para>
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</sect2>
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<sect2><title>ATA command execute</title>
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<programlisting>
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void (*exec_command)(struct ata_port *ap, struct ata_taskfile *tf);
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void (*sff_exec_command)(struct ata_port *ap, struct ata_taskfile *tf);
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</programlisting>
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<para>
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causes an ATA command, previously loaded with
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->tf_load(), to be initiated in hardware.
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Most drivers for taskfile-based hardware use ata_exec_command()
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Most drivers for taskfile-based hardware use ata_sff_exec_command()
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for this hook.
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</para>
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@ -218,8 +213,8 @@ command.
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<sect2><title>Read specific ATA shadow registers</title>
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<programlisting>
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u8 (*check_status)(struct ata_port *ap);
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u8 (*check_altstatus)(struct ata_port *ap);
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u8 (*sff_check_status)(struct ata_port *ap);
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u8 (*sff_check_altstatus)(struct ata_port *ap);
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</programlisting>
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<para>
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@ -227,20 +222,14 @@ u8 (*check_altstatus)(struct ata_port *ap);
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hardware. On some hardware, reading the Status register has
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the side effect of clearing the interrupt condition.
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Most drivers for taskfile-based hardware use
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ata_check_status() for this hook.
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</para>
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<para>
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Note that because this is called from ata_device_add(), at
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least a dummy function that clears device interrupts must be
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provided for all drivers, even if the controller doesn't
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actually have a taskfile status register.
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ata_sff_check_status() for this hook.
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</para>
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</sect2>
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<sect2><title>Select ATA device on bus</title>
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<programlisting>
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void (*dev_select)(struct ata_port *ap, unsigned int device);
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void (*sff_dev_select)(struct ata_port *ap, unsigned int device);
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</programlisting>
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<para>
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@ -251,9 +240,7 @@ void (*dev_select)(struct ata_port *ap, unsigned int device);
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</para>
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<para>
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Most drivers for taskfile-based hardware use
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ata_std_dev_select() for this hook. Controllers which do not
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support second drives on a port (such as SATA contollers) will
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use ata_noop_dev_select().
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ata_sff_dev_select() for this hook.
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</para>
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</sect2>
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@ -441,13 +428,13 @@ void (*irq_clear) (struct ata_port *);
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to struct ata_host_set.
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</para>
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<para>
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Most legacy IDE drivers use ata_interrupt() for the
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Most legacy IDE drivers use ata_sff_interrupt() for the
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irq_handler hook, which scans all ports in the host_set,
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determines which queued command was active (if any), and calls
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ata_host_intr(ap,qc).
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ata_sff_host_intr(ap,qc).
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</para>
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<para>
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Most legacy IDE drivers use ata_bmdma_irq_clear() for the
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Most legacy IDE drivers use ata_sff_irq_clear() for the
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irq_clear() hook, which simply clears the interrupt and error
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flags in the DMA status register.
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</para>
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@ -496,10 +483,6 @@ void (*host_stop) (struct ata_host_set *host_set);
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data from port at this time.
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</para>
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<para>
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Many drivers use ata_port_stop() as this hook, which frees the
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PRD table.
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</para>
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<para>
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->host_stop() is called after all ->port_stop() calls
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have completed. The hook must finalize hardware shutdown, release DMA
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and other resources, etc.
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