[Qemu-devel] [PULL 15/16] 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 are 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>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Marcel Apfelbaum <marcel@redhat.com>
Cc: John Snow <jsnow@redhat.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Kevin O'Connor <kevin@koconnor.net>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/i386/acpi-build.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 66 insertions(+), 3 deletions(-)

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 1560c75..db4ede1 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"
@@ -1228,11 +1229,60 @@ 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, FloppyDriveType type)
 {
+    Aml *dev, *fdi;
+    uint8_t maxc, maxh, maxs;
+
+    isa_fdc_get_drive_max_chs(type, &maxc, &maxh, &maxs);
+
+    dev = aml_device("FLP%c", 'A' + idx);
+
+    aml_append(dev, aml_name_decl("_ADR", aml_int(idx)));
+
+    fdi = aml_package(16);
+    aml_append(fdi, aml_int(idx));  /* Drive Number */
+    aml_append(fdi,
+        aml_int(cmos_get_fd_drive_type(type)));  /* Device Type */
+    /*
+     * the values below are the limits of the drive, and are thus independent
+     * of the inserted media
+     */
+    aml_append(fdi, aml_int(maxc));  /* Maximum Cylinder Number */
+    aml_append(fdi, aml_int(maxs));  /* Maximum Sector Number */
+    aml_append(fdi, aml_int(maxh));  /* 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;
 
+#define ACPI_FDE_MAX_FD 4
+    uint32_t fde_buf[5] = {
+        0, 0, 0, 0,     /* presence of floppy drives #0 - #3 */
+        cpu_to_le32(2)  /* tape presence (2 == never present) */
+    };
+
     dev = aml_device("FDC0");
     aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0700")));
 
@@ -1244,6 +1294,17 @@ 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 < MIN(MAX_FD, ACPI_FDE_MAX_FD); i++) {
+        FloppyDriveType type = isa_fdc_get_drive_type(fdc, i);
+
+        if (type < FLOPPY_DRIVE_TYPE_NONE) {
+            fde_buf[i] = cpu_to_le32(1);  /* drive present */
+            aml_append(dev, build_fdinfo_aml(i, type));
+        }
+    }
+    aml_append(dev, aml_name_decl("_FDE",
+               aml_buffer(sizeof(fde_buf), (uint8_t *)fde_buf)));
+
     return dev;
 }
 
@@ -1388,13 +1449,15 @@ 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