On 05/07/2010 02:47 PM, Sergei Shtylyov wrote:
The set of libata's taskfile access methods is clearly incomplete as it lacks
a method to write to the device control register -- which forces drivers like
'pata_bf54x' and 'pata_scc' to implement more "high level" (and more weighty)
methods like freeze() and postreset().
So, introduce the optional sff_set_devctl() method which the drivers only have
to implement if the standard iowrite8() can't be used (just like the existing
sff_check_altstatus() method) and make use of it in the freeze() and postreset()
method implementations (I could also have used it in softreset() method but it
also reads other taskfile registers without using tf_read() making that quite
pointless); this makes freeze() method implementations in the 'pata_bf54x' and
'pata_scc' methods virtually identical to ata_sff_freeze(), so we can get rid
of them completely.
Signed-off-by: Sergei Shtylyov<sshtylyov@xxxxxxxxxxxxx>
---
The patch is against the recent Linus' tree.
Documentation/DocBook/libata.tmpl | 12 +++++++++++
drivers/ata/libata-sff.c | 31 +++++++++++++++++++++++------
drivers/ata/pata_bf54x.c | 40 ++++++++++++--------------------------
drivers/ata/pata_scc.c | 38 +++++++++++-------------------------
include/linux/libata.h | 1
5 files changed, 63 insertions(+), 59 deletions(-)
Index: linux-2.6/Documentation/DocBook/libata.tmpl
===================================================================
--- linux-2.6.orig/Documentation/DocBook/libata.tmpl
+++ linux-2.6/Documentation/DocBook/libata.tmpl
@@ -225,6 +225,18 @@ u8 (*sff_check_altstatus)(struct ata_p
</sect2>
+ <sect2><title>Write specific ATA shadow register</title>
+ <programlisting>
+void (*sff_set_devctl)(struct ata_port *ap, u8 ctl);
+ </programlisting>
+
+ <para>
+ Write the device control ATA shadow register to the hardware.
+ Most drivers don't need to define this.
+ </para>
+
+ </sect2>
+
<sect2><title>Select ATA device on bus</title>
<programlisting>
void (*sff_dev_select)(struct ata_port *ap, unsigned int device);
Index: linux-2.6/drivers/ata/libata-sff.c
===================================================================
--- linux-2.6.orig/drivers/ata/libata-sff.c
+++ linux-2.6/drivers/ata/libata-sff.c
@@ -446,6 +446,27 @@ int ata_sff_wait_ready(struct ata_link *
EXPORT_SYMBOL_GPL(ata_sff_wait_ready);
/**
+ * ata_sff_set_devctl - Write device control reg
+ * @ap: port where the device is
+ * @ctl: value to write
+ *
+ * Writes ATA taskfile device control register.
+ *
+ * Note: may NOT be used as the sff_set_devctl() entry in
+ * ata_port_operations.
+ *
+ * LOCKING:
+ * Inherited from caller.
+ */
+static void ata_sff_set_devctl(struct ata_port *ap, u8 ctl)
+{
+ if (ap->ops->sff_set_devctl)
+ ap->ops->sff_set_devctl(ap, ctl);
+ else
+ iowrite8(ctl, ap->ioaddr.ctl_addr);
+}
+
+/**
* ata_sff_dev_select - Select device 0/1 on ATA bus
* @ap: ATA channel to manipulate
* @device: ATA device (numbered from zero) to select
@@ -1895,13 +1916,11 @@ EXPORT_SYMBOL_GPL(ata_sff_lost_interrupt
*/
void ata_sff_freeze(struct ata_port *ap)
{
- struct ata_ioports *ioaddr =&ap->ioaddr;
-
ap->ctl |= ATA_NIEN;
ap->last_ctl = ap->ctl;
- if (ioaddr->ctl_addr)
- iowrite8(ap->ctl, ioaddr->ctl_addr);
+ if (ap->ops->sff_set_devctl || ap->ioaddr.ctl_addr)
+ ata_sff_set_devctl(ap, ap->ctl);
/* Under certain circumstances, some controllers raise IRQ on
* ATA_NIEN manipulation. Also, many controllers fail to mask
@@ -2301,8 +2320,8 @@ void ata_sff_postreset(struct ata_link *
}
/* set up device control */
- if (ap->ioaddr.ctl_addr) {
- iowrite8(ap->ctl, ap->ioaddr.ctl_addr);
+ if (ap->ops->sff_set_devctl || ap->ioaddr.ctl_addr) {
+ ata_sff_set_devctl(ap, ap->ctl);
ap->last_ctl = ap->ctl;
Applied, however, I think ata_sff_set_devctl() interface is a bit
inefficient. It requires the programmer to execute certain checks prior
to calling ata_sff_set_devctl(), while other checks
(ap->ops->sff_set_devctl) are duplicated.
It seems like better logic would put all those checks inside
ata_sff_set_devctl(), like this:
int ata_sff_set_devctl()
{
if (ap->ops->...)
call hook
else if (ap->ioaddr.ctl_addr)
iowrite
else
return -EOPNOTSUPP;
return 0;
}
That sort of implementation with create a no-op set_devctl(), which
would permit callers to call that function unconditionally -- and ignore
the error result, if they previously would have called
ata_sff_set_devctl() conditionally.
Jeff
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