ahci_xgene: Implement the xgene_ahci_poll_reg_val to support PMP.

This patch implements the function xgene_ahci_poll_reg_val
to poll PxCI for multiple IDENTIFY DEVICE commands to finish before
restarting the DMA engine.

Signed-off-by: Suman Tripathi <stripathi@apm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/drivers/ata/ahci_xgene.c b/drivers/ata/ahci_xgene.c
index cbcd2081035573e9897db0afd475224c176231d3..afa9c03ecfd628214ba9f139e1099c00c254ad3e 100644 (file)
--- a/drivers/ata/ahci_xgene.c
+++ b/drivers/ata/ahci_xgene.c
@@ -104,18 +104,70 @@ static int xgene_ahci_init_memram(struct xgene_ahci_context *ctx)
        return 0;
 }
 
+/**
+ * xgene_ahci_poll_reg_val- Poll a register on a specific value.
+ * @ap : ATA port of interest.
+ * @reg : Register of interest.
+ * @val : Value to be attained.
+ * @interval : waiting interval for polling.
+ * @timeout : timeout for achieving the value.
+ */
+static int xgene_ahci_poll_reg_val(struct ata_port *ap,
+                                  void __iomem *reg, unsigned
+                                  int val, unsigned long interval,
+                                  unsigned long timeout)
+{
+       unsigned long deadline;
+       unsigned int tmp;
+
+       tmp = ioread32(reg);
+       deadline = ata_deadline(jiffies, timeout);
+
+       while (tmp != val && time_before(jiffies, deadline)) {
+               ata_msleep(ap, interval);
+               tmp = ioread32(reg);
+       }
+
+       return tmp;
+}
+
 /**
  * xgene_ahci_restart_engine - Restart the dma engine.
  * @ap : ATA port of interest
  *
- * Restarts the dma engine inside the controller.
+ * Waits for completion of multiple commands and restarts
+ * the DMA engine inside the controller.
  */
 static int xgene_ahci_restart_engine(struct ata_port *ap)
 {
        struct ahci_host_priv *hpriv = ap->host->private_data;
+       struct ahci_port_priv *pp = ap->private_data;
+       void __iomem *port_mmio = ahci_port_base(ap);
+       u32 fbs;
+
+       /*
+        * In case of PMP multiple IDENTIFY DEVICE commands can be
+        * issued inside PxCI. So need to poll PxCI for the
+        * completion of outstanding IDENTIFY DEVICE commands before
+        * we restart the DMA engine.
+        */
+       if (xgene_ahci_poll_reg_val(ap, port_mmio +
+                                   PORT_CMD_ISSUE, 0x0, 1, 100))
+                 return -EBUSY;
 
        ahci_stop_engine(ap);
        ahci_start_fis_rx(ap);
+
+       /*
+        * Enable the PxFBS.FBS_EN bit as it
+        * gets cleared due to stopping the engine.
+        */
+       if (pp->fbs_supported) {
+               fbs = readl(port_mmio + PORT_FBS);
+               writel(fbs | PORT_FBS_EN, port_mmio + PORT_FBS);
+               fbs = readl(port_mmio + PORT_FBS);
+       }
+
        hpriv->start_engine(ap);
 
        return 0;
@@ -374,7 +426,7 @@ static struct ata_port_operations xgene_ahci_ops = {
 };
 
 static const struct ata_port_info xgene_ahci_port_info = {
-       .flags = AHCI_FLAG_COMMON,
+       .flags = AHCI_FLAG_COMMON | ATA_FLAG_PMP,
        .pio_mask = ATA_PIO4,
        .udma_mask = ATA_UDMA6,
        .port_ops = &xgene_ahci_ops,