[PATCH] libata: add a function to decide if we need iordy

[deliverable/linux.git] / drivers / scsi / libata-core.c

diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index bc48d88fef5a3b912359618f1f9d9152449da07e..b42acbe0e9a5e60684ed4e4fc42dcf1beb1630f2 100644 (file)
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -1168,6 +1168,39 @@ ata_exec_internal(struct ata_port *ap, struct ata_device *dev,
        return AC_ERR_OTHER;
 }
 
+/**
+ *     ata_pio_need_iordy      -       check if iordy needed
+ *     @adev: ATA device
+ *
+ *     Check if the current speed of the device requires IORDY. Used
+ *     by various controllers for chip configuration.
+ */
+
+unsigned int ata_pio_need_iordy(const struct ata_device *adev)
+{
+       int pio;
+       int speed = adev->pio_mode - XFER_PIO_0;
+
+       if (speed < 2)
+               return 0;
+       if (speed > 2)
+               return 1;
+               
+       /* If we have no drive specific rule, then PIO 2 is non IORDY */
+
+       if (adev->id[ATA_ID_FIELD_VALID] & 2) { /* EIDE */
+               pio = adev->id[ATA_ID_EIDE_PIO];
+               /* Is the speed faster than the drive allows non IORDY ? */
+               if (pio) {
+                       /* This is cycle times not frequency - watch the logic! */
+                       if (pio > 240)  /* PIO2 is 240nS per cycle */
+                               return 1;
+                       return 0;
+               }
+       }
+       return 0;
+}
+
 /**
  *     ata_dev_identify - obtain IDENTIFY x DEVICE page
  *     @ap: port on which device we wish to probe resides
@@ -5126,6 +5159,7 @@ EXPORT_SYMBOL_GPL(ata_dev_id_string);
 EXPORT_SYMBOL_GPL(ata_dev_config);
 EXPORT_SYMBOL_GPL(ata_scsi_simulate);
 
+EXPORT_SYMBOL_GPL(ata_pio_need_iordy);
 EXPORT_SYMBOL_GPL(ata_timing_compute);
 EXPORT_SYMBOL_GPL(ata_timing_merge);