libata: introduce sff_set_devctl() method

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 <[e-mail]>
Signed-off-by: Jeff Garzik <[e-mail]>

Documentation/DocBook/libata.tmpl

···
 
 	</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);

drivers/ata/libata-sff.c

···
 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
···
  */
 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
···
 	}
 
 	/* 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;
 	}
 }

drivers/ata/pata_bf54x.c

···
 }
 
 /**
+ *	bfin_set_devctl - Write device control reg
+ *	@ap: port where the device is
+ *	@ctl: value to write
+ */
+
+static u8 bfin_set_devctl(struct ata_port *ap, u8 ctl)
+{
+	void __iomem *base = (void __iomem *)ap->ioaddr.ctl_addr;
+	write_atapi_register(base, ATA_REG_CTRL, ctl);
+}
+
+/**
  *	bfin_bmdma_setup - Set up IDE DMA transaction
  *	@qc: Info associated with this ATA transaction.
  *
···
 }
 
 /**
- *	bfin_freeze - Freeze DMA controller port
- *	@ap: port to freeze
- *
- *	Note: Original code is ata_sff_freeze().
- */
-
-static void bfin_freeze(struct ata_port *ap)
-{
-	void __iomem *base = (void __iomem *)ap->ioaddr.ctl_addr;
-
-	dev_dbg(ap->dev, "in atapi dma freeze\n");
-	ap->ctl |= ATA_NIEN;
-	ap->last_ctl = ap->ctl;
-
-	write_atapi_register(base, ATA_REG_CTRL, ap->ctl);
-
-	/* Under certain circumstances, some controllers raise IRQ on
-	 * ATA_NIEN manipulation.  Also, many controllers fail to mask
-	 * previously pending IRQ on ATA_NIEN assertion.  Clear it.
-	 */
-	ap->ops->sff_check_status(ap);
-
-	bfin_irq_clear(ap);
-}
-
-/**
  *	bfin_thaw - Thaw DMA controller port
  *	@ap: port to thaw
  *
···
 	.sff_check_status	= bfin_check_status,
 	.sff_check_altstatus	= bfin_check_altstatus,
 	.sff_dev_select		= bfin_dev_select,
+	.sff_set_devctl		= bfin_set_devctl,
 
 	.bmdma_setup		= bfin_bmdma_setup,
 	.bmdma_start		= bfin_bmdma_start,
···
 
 	.qc_prep		= ata_noop_qc_prep,
 
-	.freeze			= bfin_freeze,
 	.thaw			= bfin_thaw,
 	.softreset		= bfin_softreset,
 	.postreset		= bfin_postreset,

drivers/ata/pata_scc.c

···
 }
 
 /**
+ *	scc_set_devctl - Write device control reg
+ *	@ap: port where the device is
+ *	@ctl: value to write
+ */
+
+static void scc_set_devctl(struct ata_port *ap, u8 ctl)
+{
+	out_be32(ap->ioaddr.ctl_addr, ctl);
+}
+
+/**
  *	scc_bmdma_setup - Set up PCI IDE BMDMA transaction
  *	@qc: Info associated with this ATA transaction.
  *
···
 }
 
 /**
- *	scc_freeze - Freeze BMDMA controller port
- *	@ap: port to freeze
- *
- *	Note: Original code is ata_sff_freeze().
- */
-
-static void scc_freeze (struct ata_port *ap)
-{
-	struct ata_ioports *ioaddr = &ap->ioaddr;
-
-	ap->ctl |= ATA_NIEN;
-	ap->last_ctl = ap->ctl;
-
-	out_be32(ioaddr->ctl_addr, ap->ctl);
-
-	/* Under certain circumstances, some controllers raise IRQ on
-	 * ATA_NIEN manipulation.  Also, many controllers fail to mask
-	 * previously pending IRQ on ATA_NIEN assertion.  Clear it.
-	 */
-	ap->ops->sff_check_status(ap);
-
-	ap->ops->sff_irq_clear(ap);
-}
-
-/**
  *	scc_pata_prereset - prepare for reset
  *	@ap: ATA port to be reset
  *	@deadline: deadline jiffies for the operation
···
 	.sff_check_status	= scc_check_status,
 	.sff_check_altstatus	= scc_check_altstatus,
 	.sff_dev_select		= scc_dev_select,
+	.sff_set_devctl		= scc_set_devctl,
 
 	.bmdma_setup		= scc_bmdma_setup,
 	.bmdma_start		= scc_bmdma_start,
···
 	.bmdma_status		= scc_bmdma_status,
 	.sff_data_xfer		= scc_data_xfer,
 
-	.freeze			= scc_freeze,
 	.prereset		= scc_pata_prereset,
 	.softreset		= scc_softreset,
 	.postreset		= scc_postreset,

include/linux/libata.h

···
 	 * SFF / taskfile oriented ops
 	 */
 	void (*sff_dev_select)(struct ata_port *ap, unsigned int device);
+	void (*sff_set_devctl)(struct ata_port *ap, u8 ctl);
 	u8   (*sff_check_status)(struct ata_port *ap);
 	u8   (*sff_check_altstatus)(struct ata_port *ap);
 	void (*sff_tf_load)(struct ata_port *ap, const struct ata_taskfile *tf);