[Qemu-devel] [PULL 48/49] i386: populate floppy drive information in DSDT

["Michael S. Tsirkin" <mst@redhat.com>]

From: Roman Kagan <rkagan@virtuozzo.com>

On x86-based systems Linux determines the presence
and the type of floppy drives via a query of a CMOS field.
So does SeaBIOS when populating the return data for
int 0x13 function 0x08.

However Windows doesn't do it. Instead, it requests
this information from BIOS via int 0x13/0x08 or through
ACPI objects _FDE (Floppy Drive Enumerate) and _FDI
(Floppy Drive Information) of the floppy controller object.
On UEFI systems only ACPI-based detection is supported.

QEMU doesn't provide those objects in its ACPI tables
and as a result floppy drives aren't invisible to Windows
on UEFI/OVMF.

This patch adds those objects to the floppy controller
in DSDT, populating them with the information from
respective QEMU objects.

Signed-off-by: Roman Kagan <rkagan@virtuozzo.com>
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/i386/acpi-build.c | 61 +++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 58 insertions(+), 3 deletions(-)

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 842c731..caa2e87 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -37,6 +37,7 @@
 #include "hw/acpi/bios-linker-loader.h"
 #include "hw/loader.h"
 #include "hw/isa/isa.h"
+#include "hw/block/fdc.h"
 #include "hw/acpi/memory_hotplug.h"
 #include "hw/mem/nvdimm.h"
 #include "sysemu/tpm.h"
@@ -1227,10 +1228,47 @@ static void build_hpet_aml(Aml *table)
     aml_append(table, scope);
 }
 
-static Aml *build_fdc_device_aml(void)
+static Aml *build_fdinfo_aml(int idx, uint8_t type, uint8_t cylinders,
+                             uint8_t heads, uint8_t sectors)
+{
+    Aml *dev, *fdi;
+
+    dev = aml_device("FLP%c", 'A' + idx);
+
+    aml_append(dev, aml_name_decl("_ADR", aml_int(idx)));
+
+    fdi = aml_package(0x10);
+    aml_append(fdi, aml_int(idx));  /* Drive Number */
+    aml_append(fdi,
+        aml_int(cmos_get_fd_drive_type(type)));  /* Device Type */
+    aml_append(fdi,
+        aml_int(cylinders - 1));  /* Maximum Cylinder Number */
+    aml_append(fdi, aml_int(sectors));  /* Maximum Sector Number */
+    aml_append(fdi, aml_int(heads - 1));  /* Maximum Head Number */
+    /* SeaBIOS returns the below values for int 0x13 func 0x08 regardless of
+     * the drive type, so shall we */
+    aml_append(fdi, aml_int(0xAF));  /* disk_specify_1 */
+    aml_append(fdi, aml_int(0x02));  /* disk_specify_2 */
+    aml_append(fdi, aml_int(0x25));  /* disk_motor_wait */
+    aml_append(fdi, aml_int(0x02));  /* disk_sector_siz */
+    aml_append(fdi, aml_int(0x12));  /* disk_eot */
+    aml_append(fdi, aml_int(0x1B));  /* disk_rw_gap */
+    aml_append(fdi, aml_int(0xFF));  /* disk_dtl */
+    aml_append(fdi, aml_int(0x6C));  /* disk_formt_gap */
+    aml_append(fdi, aml_int(0xF6));  /* disk_fill */
+    aml_append(fdi, aml_int(0x0F));  /* disk_head_sttl */
+    aml_append(fdi, aml_int(0x08));  /* disk_motor_strt */
+
+    aml_append(dev, aml_name_decl("_FDI", fdi));
+    return dev;
+}
+
+static Aml *build_fdc_device_aml(ISADevice *fdc)
 {
+    int i;
     Aml *dev;
     Aml *crs;
+    uint32_t fde_buf[5] = {0, 0, 0, 0, cpu_to_le32(0x2)};
 
     dev = aml_device("FDC0");
     aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0700")));
@@ -1243,6 +1281,21 @@ static Aml *build_fdc_device_aml(void)
         aml_dma(AML_COMPATIBILITY, AML_NOTBUSMASTER, AML_TRANSFER8, 2));
     aml_append(dev, aml_name_decl("_CRS", crs));
 
+    for (i = 0; i < MAX_FD; i++) {
+        uint8_t type = isa_fdc_get_drive_type(fdc, i);
+
+        if (type < FLOPPY_DRIVE_TYPE_NONE) {
+            uint8_t cylinders, heads, sectors;
+
+            fde_buf[i] = cpu_to_le32(0x1);
+            isa_fdc_get_drive_geometry(fdc, i, &cylinders, &heads, &sectors);
+            aml_append(dev,
+                build_fdinfo_aml(i, type, cylinders, heads, sectors));
+        }
+    }
+    aml_append(dev, aml_name_decl("_FDE",
+               aml_buffer(sizeof(fde_buf), (uint8_t *) fde_buf)));
+
     return dev;
 }
 
@@ -1387,13 +1440,15 @@ static Aml *build_com_device_aml(uint8_t uid)
 
 static void build_isa_devices_aml(Aml *table)
 {
+    ISADevice *fdc = pc_find_fdc0();
+
     Aml *scope = aml_scope("_SB.PCI0.ISA");
 
     aml_append(scope, build_rtc_device_aml());
     aml_append(scope, build_kbd_device_aml());
     aml_append(scope, build_mouse_device_aml());
-    if (!!pc_find_fdc0()) {
-        aml_append(scope, build_fdc_device_aml());
+    if (!!fdc) {
+        aml_append(scope, build_fdc_device_aml(fdc));
     }
     aml_append(scope, build_lpt_device_aml());
     aml_append(scope, build_com_device_aml(1));
-- 
MST