acpi: add fw_cfg device node to dsdt

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Merge remote-tracking branch 'remotes/kraxel/tags/pull-fw-cfg-20160308-1' into staging

acpi: add fw_cfg device node to dsdt

# gpg: Signature made Tue 08 Mar 2016 11:15:42 GMT using RSA key ID D3E87138
# gpg: Good signature from "Gerd Hoffmann (work) <kraxel@redhat.com>"
# gpg:                 aka "Gerd Hoffmann <gerd@kraxel.org>"
# gpg:                 aka "Gerd Hoffmann (private) <kraxel@gmail.com>"

* remotes/kraxel/tags/pull-fw-cfg-20160308-1:
  tests: update acpi test data
  fw_cfg: document ACPI device node information
  acpi: arm: add fw_cfg device node to dsdt
  acpi: pc: add fw_cfg device node to dsdt
  pc: fw_cfg: move ioport base constant to pc.h
  fw_cfg: expose control register size in fw_cfg.h

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

docs/specs/fw_cfg.txt

@@ -84,6 +84,15 @@ Selector Register address: Base + 8 (2 bytes)
 Data Register address:     Base + 0 (8 bytes)
 DMA Address address:       Base + 16 (8 bytes)
 
+== ACPI Interface ==
+
+The fw_cfg device is defined with ACPI ID "QEMU0002". Since we expect
+ACPI tables to be passed into the guest through the fw_cfg device itself,
+the guest-side firmware can not use ACPI to find fw_cfg. However, once the
+firmware is finished setting up ACPI tables and hands control over to the
+guest kernel, the latter can use the fw_cfg ACPI node for a more accurate
+inventory of in-use IOport or MMIO regions.
+
 == Firmware Configuration Items ==
 
 === Signature (Key 0x0000, FW_CFG_SIGNATURE) ===

hw/arm/virt-acpi-build.c

@@ -81,6 +81,20 @@ static void acpi_dsdt_add_uart(Aml *scope, const MemMapEntry *uart_memmap,
     aml_append(scope, dev);
 }
 
+static void acpi_dsdt_add_fw_cfg(Aml *scope, const MemMapEntry *fw_cfg_memmap)
+{
+    Aml *dev = aml_device("FWCF");
+    aml_append(dev, aml_name_decl("_HID", aml_string("QEMU0002")));
+    /* device present, functioning, decoding, not shown in UI */
+    aml_append(dev, aml_name_decl("_STA", aml_int(0xB)));
+
+    Aml *crs = aml_resource_template();
+    aml_append(crs, aml_memory32_fixed(fw_cfg_memmap->base,
+                                       fw_cfg_memmap->size, AML_READ_WRITE));
+    aml_append(dev, aml_name_decl("_CRS", crs));
+    aml_append(scope, dev);
+}
+
 static void acpi_dsdt_add_flash(Aml *scope, const MemMapEntry *flash_memmap)
 {
     Aml *dev, *crs;
@@ -549,6 +563,7 @@ build_dsdt(GArray *table_data, GArray *linker, VirtGuestInfo *guest_info)
     acpi_dsdt_add_uart(scope, &memmap[VIRT_UART],
                        (irqmap[VIRT_UART] + ARM_SPI_BASE));
     acpi_dsdt_add_flash(scope, &memmap[VIRT_FLASH]);
+    acpi_dsdt_add_fw_cfg(scope, &memmap[VIRT_FW_CFG]);
     acpi_dsdt_add_virtio(scope, &memmap[VIRT_MMIO],
                     (irqmap[VIRT_MMIO] + ARM_SPI_BASE), NUM_VIRTIO_TRANSPORTS);
     acpi_dsdt_add_pci(scope, memmap, (irqmap[VIRT_PCIE] + ARM_SPI_BASE),

hw/i386/acpi-build.c

@@ -2190,6 +2190,35 @@ build_dsdt(GArray *table_data, GArray *linker,
     aml_append(scope, aml_name_decl("_S5", pkg));
     aml_append(dsdt, scope);
 
+    /* create fw_cfg node, unconditionally */
+    {
+        /* when using port i/o, the 8-bit data register *always* overlaps
+         * with half of the 16-bit control register. Hence, the total size
+         * of the i/o region used is FW_CFG_CTL_SIZE; when using DMA, the
+         * DMA control register is located at FW_CFG_DMA_IO_BASE + 4 */
+        uint8_t io_size = object_property_get_bool(OBJECT(pcms->fw_cfg),
+                                                   "dma_enabled", NULL) ?
+                          ROUND_UP(FW_CFG_CTL_SIZE, 4) + sizeof(dma_addr_t) :
+                          FW_CFG_CTL_SIZE;
+
+        scope = aml_scope("\\_SB.PCI0");
+        dev = aml_device("FWCF");
+
+        aml_append(dev, aml_name_decl("_HID", aml_string("QEMU0002")));
+
+        /* device present, functioning, decoding, not shown in UI */
+        aml_append(dev, aml_name_decl("_STA", aml_int(0xB)));
+
+        crs = aml_resource_template();
+        aml_append(crs,
+            aml_io(AML_DECODE16, FW_CFG_IO_BASE, FW_CFG_IO_BASE, 0x01, io_size)
+        );
+        aml_append(dev, aml_name_decl("_CRS", crs));
+
+        aml_append(scope, dev);
+        aml_append(dsdt, scope);
+    }
+
     if (misc->applesmc_io_base) {
         scope = aml_scope("\\_SB.PCI0.ISA");
         dev = aml_device("SMC");

hw/i386/pc.c

@@ -78,7 +78,6 @@
 #define DPRINTF(fmt, ...)
 #endif
 
-#define BIOS_CFG_IOPORT 0x510
 #define FW_CFG_ACPI_TABLES (FW_CFG_ARCH_LOCAL + 0)
 #define FW_CFG_SMBIOS_ENTRIES (FW_CFG_ARCH_LOCAL + 1)
 #define FW_CFG_IRQ0_OVERRIDE (FW_CFG_ARCH_LOCAL + 2)
@@ -756,7 +755,7 @@ static FWCfgState *bochs_bios_init(AddressSpace *as)
     int i, j;
     unsigned int apic_id_limit = pc_apic_id_limit(max_cpus);
 
-    fw_cfg = fw_cfg_init_io_dma(BIOS_CFG_IOPORT, BIOS_CFG_IOPORT + 4, as);
+    fw_cfg = fw_cfg_init_io_dma(FW_CFG_IO_BASE, FW_CFG_IO_BASE + 4, as);
 
     /* FW_CFG_MAX_CPUS is a bit confusing/problematic on x86:
      *
@@ -1258,7 +1257,7 @@ void xen_load_linux(PCMachineState *pcms)
 
     assert(MACHINE(pcms)->kernel_filename != NULL);
 
-    fw_cfg = fw_cfg_init_io(BIOS_CFG_IOPORT);
+    fw_cfg = fw_cfg_init_io(FW_CFG_IO_BASE);
     rom_set_fw(fw_cfg);
 
     load_linux(pcms, fw_cfg);

hw/nvram/fw_cfg.c

@@ -32,7 +32,6 @@
 #include "qemu/error-report.h"
 #include "qemu/config-file.h"
 
-#define FW_CFG_CTL_SIZE 2
 #define FW_CFG_NAME "fw_cfg"
 #define FW_CFG_PATH "/machine/" FW_CFG_NAME
 
@@ -886,6 +885,9 @@ static void fw_cfg_io_realize(DeviceState *dev, Error **errp)
     FWCfgIoState *s = FW_CFG_IO(dev);
     SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
 
+    /* when using port i/o, the 8-bit data register ALWAYS overlaps
+     * with half of the 16-bit control register. Hence, the total size
+     * of the i/o region used is FW_CFG_CTL_SIZE */
     memory_region_init_io(&s->comb_iomem, OBJECT(s), &fw_cfg_comb_mem_ops,
                           FW_CFG(s), "fwcfg", FW_CFG_CTL_SIZE);
     sysbus_add_io(sbd, s->iobase, &s->comb_iomem);

include/hw/i386/pc.h

@@ -266,6 +266,8 @@ void ioapic_init_gsi(GSIState *gsi_state, const char *parent_name);
 
 ISADevice *pc_find_fdc0(void);
 
+#define FW_CFG_IO_BASE     0x510
+
 /* acpi_piix.c */
 
 I2CBus *piix4_pm_init(PCIBus *bus, int devfn, uint32_t smb_io_base,

include/hw/nvram/fw_cfg.h

@@ -44,6 +44,9 @@
 
 #define FW_CFG_INVALID          0xffff
 
+/* width in bytes of fw_cfg control register */
+#define FW_CFG_CTL_SIZE         0x02
+
 #define FW_CFG_MAX_FILE_PATH    56
 
 #ifndef NO_QEMU_PROTOS