[SeaBIOS] [PATCH 2/7] ahci: use interrupt status register

[Gerd Hoffmann]

Poll interrupt status register to figure when the device has updated the
status and possibly finished the request, continue polling until BSY is
clear as we might see multiple status updates per request.

Signed-off-by: Gerd Hoffmann 
---
 src/ahci.c |   43 ++++++++++++++++++++++++++++---------------
 1 files changed, 28 insertions(+), 15 deletions(-)

diff --git a/src/ahci.c b/src/ahci.c
index 058416c..9ff1324 100644
--- a/src/ahci.c
+++ b/src/ahci.c
@@ -105,7 +105,7 @@ static void ahci_port_writel(struct ahci_ctrl_s *ctrl, u32 pnr, u32 reg, u32 val
 static int ahci_command(struct ahci_port_s *port, int iswrite, int isatapi,
                         void *buffer, u32 bsize)
 {
-    u32 val, status, success, flags;
+    u32 val, status, success, flags, intbits;
     struct ahci_ctrl_s *ctrl = GET_GLOBAL(port->ctrl);
     struct ahci_cmd_s  *cmd  = GET_GLOBAL(port->cmd);
     struct ahci_fis_s  *fis  = GET_GLOBAL(port->fis);
@@ -118,12 +118,6 @@ static int ahci_command(struct ahci_port_s *port, int iswrite, int isatapi,
     SET_FLATPTR(cmd->prdt[0].baseu, 0);
     SET_FLATPTR(cmd->prdt[0].flags, bsize-1);

-    val = ahci_port_readl(ctrl, pnr, PORT_CMD);
-    ahci_port_writel(ctrl, pnr, PORT_CMD, val | PORT_CMD_START);
-
-    if (ahci_port_readl(ctrl, pnr, PORT_CMD_ISSUE))
-        return -1;
-
     flags = ((1 << 16) | /* one prd entry */
              (iswrite ? (1 << 6) : 0) |
              (isatapi ? (1 << 5) : 0) |
@@ -134,15 +128,31 @@ static int ahci_command(struct ahci_port_s *port, int iswrite, int isatapi,
     SET_FLATPTR(list[0].baseu,  0);

dprintf(2, "AHCI/%d: send cmd ...\n", pnr);
-    SET_FLATPTR(fis->rfis[2], 0);
+    intbits = ahci_port_readl(ctrl, pnr, PORT_IRQ_STAT);
+    if (intbits)
+        ahci_port_writel(ctrl, pnr, PORT_IRQ_STAT, intbits);
     ahci_port_writel(ctrl, pnr, PORT_SCR_ACT, 1);
     ahci_port_writel(ctrl, pnr, PORT_CMD_ISSUE, 1);
-    while (ahci_port_readl(ctrl, pnr, PORT_CMD_ISSUE)) {
-        yield();
-    }
-    while ((status = GET_FLATPTR(fis->rfis[2])) == 0) {
-        yield();
-    }
+
+    do {
+        for (;;) {
+            intbits = ahci_port_readl(ctrl, pnr, PORT_IRQ_STAT);
+            if (intbits) {
+                ahci_port_writel(ctrl, pnr, PORT_IRQ_STAT, intbits);
+                if (intbits & 0x02) {
+                    status = GET_FLATPTR(fis->psfis[2]);
+                    break;
+                }
+                if (intbits & 0x01) {
+                    status = GET_FLATPTR(fis->rfis[2]);
+                    break;
+                }
+            }
+            yield();
+        }
+        dprintf(2, "AHCI/%d: ... intbits 0x%x, status 0x%x ...\n",
+                pnr, intbits, status);
+    } while (status & ATA_CB_STAT_BSY);

success = (0x00 == (status & (ATA_CB_STAT_BSY | ATA_CB_STAT_DF |
                                   ATA_CB_STAT_DRQ | ATA_CB_STAT_ERR)) &&
@@ -329,7 +339,10 @@ ahci_port_init(struct ahci_ctrl_s *ctrl, u32 pnr)
     ahci_port_writel(ctrl, pnr, PORT_LST_ADDR, (u32)port->list);
     ahci_port_writel(ctrl, pnr, PORT_FIS_ADDR, (u32)port->fis);
     val = ahci_port_readl(ctrl, pnr, PORT_CMD);
-    ahci_port_writel(ctrl, pnr, PORT_CMD, val | PORT_CMD_FIS_RX);
+    val |= PORT_CMD_FIS_RX;
+    ahci_port_writel(ctrl, pnr, PORT_CMD, val);
+    val |= PORT_CMD_START;
+    ahci_port_writel(ctrl, pnr, PORT_CMD, val);

sata_prep_simple(&port->cmd->fis, ATA_CMD_IDENTIFY_PACKET_DEVICE);
     rc = ahci_command(port, 0, 0, buffer, sizeof(buffer));