ata_piix: unify code for programming PIO and MWDMA timings

Besides making things noticably simpler it results in ~2% decrease in
the driver LOC count and also ~2% decrease in the driver binary size
(as measured on x86-32).

Fix piix_set_piomode() documentation while at it.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 38 insertions, 73 deletions

diff --git a/drivers/ata/ata_piix.c b/drivers/ata/ata_piix.c
index 75fdd026a997..69ac373c72ab 100644
--- a/drivers/ata/ata_piix.c
+++ b/drivers/ata/ata_piix.c
@@ -731,22 +731,11 @@ static int piix_pata_prereset(struct ata_link *link, unsigned long deadline)
 
 static DEFINE_SPINLOCK(piix_lock);
 
-/**
- *      piix_set_piomode - Initialize host controller PATA PIO timings
- *      @ap: Port whose timings we are configuring
- *      @adev: um
- *
- *      Set PIO mode for device, in host controller PCI config space.
- *
- *      LOCKING:
- *      None (inherited from caller).
- */
-
-static void piix_set_piomode(struct ata_port *ap, struct ata_device *adev)
+static void piix_set_timings(struct ata_port *ap, struct ata_device *adev,
+                             u8 pio)
 {
         struct pci_dev *dev     = to_pci_dev(ap->host->dev);
         unsigned long flags;
-        unsigned int pio        = adev->pio_mode - XFER_PIO_0;
         unsigned int is_slave   = (adev->devno != 0);
         unsigned int master_port= ap->port_no ? 0x42 : 0x40;
         unsigned int slave_port = 0x44;
@@ -771,10 +760,16 @@ static void piix_set_piomode(struct ata_port *ap, struct ata_device *adev)
                 control |= 1;   /* TIME1 enable */
         if (ata_pio_need_iordy(adev))
                 control |= 2;   /* IE enable */
-
         /* Intel specifies that the PPE functionality is for disk only */
         if (adev->class == ATA_DEV_ATA)
                 control |= 4;   /* PPE enable */
+        /*
+         * If the drive MWDMA is faster than it can do PIO then
+         * we must force PIO into PIO0
+         */
+        if (adev->pio_mode < XFER_PIO_0 + pio)
+                /* Enable DMA timing only */
+                control |= 8;   /* PIO cycles in PIO0 */
 
         spin_lock_irqsave(&piix_lock, flags);
 
@@ -823,6 +818,22 @@ static void piix_set_piomode(struct ata_port *ap, struct ata_device *adev)
 }
 
 /**
+ *      piix_set_piomode - Initialize host controller PATA PIO timings
+ *      @ap: Port whose timings we are configuring
+ *      @adev: Drive in question
+ *
+ *      Set PIO mode for device, in host controller PCI config space.
+ *
+ *      LOCKING:
+ *      None (inherited from caller).
+ */
+
+static void piix_set_piomode(struct ata_port *ap, struct ata_device *adev)
+{
+        piix_set_timings(ap, adev, adev->pio_mode - XFER_PIO_0);
+}
+
+/**
  *      do_pata_set_dmamode - Initialize host controller PATA PIO timings
  *      @ap: Port whose timings we are configuring
  *      @adev: Drive in question
@@ -838,31 +849,20 @@ static void do_pata_set_dmamode(struct ata_port *ap, struct ata_device *adev, in
 {
         struct pci_dev *dev     = to_pci_dev(ap->host->dev);
         unsigned long flags;
-        u8 master_port          = ap->port_no ? 0x42 : 0x40;
-        u16 master_data;
         u8 speed                = adev->dma_mode;
         int devid               = adev->devno + 2 * ap->port_no;
         u8 udma_enable          = 0;
 
-        static const     /* ISP  RTC */
-        u8 timings[][2] = { { 0, 0 },
-                            { 0, 0 },
-                            { 1, 0 },
-                            { 2, 1 },
-                            { 2, 3 }, };
-
-        spin_lock_irqsave(&piix_lock, flags);
-
-        pci_read_config_word(dev, master_port, &master_data);
-        if (ap->udma_mask)
-                pci_read_config_byte(dev, 0x48, &udma_enable);
-
         if (speed >= XFER_UDMA_0) {
-                unsigned int udma = adev->dma_mode - XFER_UDMA_0;
+                unsigned int udma = speed - XFER_UDMA_0;
                 u16 udma_timing;
                 u16 ideconf;
                 int u_clock, u_speed;
 
+                spin_lock_irqsave(&piix_lock, flags);
+
+                pci_read_config_byte(dev, 0x48, &udma_enable);
+
                 /*
                  * UDMA is handled by a combination of clock switching and
                  * selection of dividers
@@ -895,56 +895,21 @@ static void do_pata_set_dmamode(struct ata_port *ap, struct ata_device *adev, in
                            performance (WR_PingPong_En) */
                         pci_write_config_word(dev, 0x54, ideconf);
                 }
+
+                pci_write_config_byte(dev, 0x48, udma_enable);
+
+                spin_unlock_irqrestore(&piix_lock, flags);
         } else {
-                /*
-                 * MWDMA is driven by the PIO timings. We must also enable
-                 * IORDY unconditionally along with TIME1. PPE has already
-                 * been set when the PIO timing was set.
-                 */
-                unsigned int mwdma      = adev->dma_mode - XFER_MW_DMA_0;
-                unsigned int control;
-                u8 slave_data;
+                /* MWDMA is driven by the PIO timings. */
+                unsigned int mwdma = speed - XFER_MW_DMA_0;
                 const unsigned int needed_pio[3] = {
                         XFER_PIO_0, XFER_PIO_3, XFER_PIO_4
                 };
                 int pio = needed_pio[mwdma] - XFER_PIO_0;
 
-                control = 3;    /* IORDY|TIME1 */
-
-                /* If the drive MWDMA is faster than it can do PIO then
-                   we must force PIO into PIO0 */
-
-                if (adev->pio_mode < needed_pio[mwdma])
-                        /* Enable DMA timing only */
-                        control |= 8;   /* PIO cycles in PIO0 */
-
-                if (adev->devno) {      /* Slave */
-                        master_data &= 0xFF4F;  /* Mask out IORDY|TIME1|DMAONLY */
-                        master_data |= control << 4;
-                        pci_read_config_byte(dev, 0x44, &slave_data);
-                        slave_data &= (ap->port_no ? 0x0f : 0xf0);
-                        /* Load the matching timing */
-                        slave_data |= ((timings[pio][0] << 2) | timings[pio][1]) << (ap->port_no ? 4 : 0);
-                        pci_write_config_byte(dev, 0x44, slave_data);
-                } else {        /* Master */
-                        master_data &= 0xCCF4;  /* Mask out IORDY|TIME1|DMAONLY
-                                                   and master timing bits */
-                        master_data |= control;
-                        master_data |=
-                                (timings[pio][0] << 12) |
-                                (timings[pio][1] << 8);
-                }
-
-                if (ap->udma_mask)
-                        udma_enable &= ~(1 << devid);
-
-                pci_write_config_word(dev, master_port, master_data);
+                /* XFER_PIO_0 is never used currently */
+                piix_set_timings(ap, adev, pio);
         }
-        /* Don't scribble on 0x48 if the controller does not support UDMA */
-        if (ap->udma_mask)
-                pci_write_config_byte(dev, 0x48, udma_enable);
-
-        spin_unlock_irqrestore(&piix_lock, flags);
 }
 
 /**