The QEMU fw_cfg interface allows the guest to retrieve various data
information from QEMU. For example, APCI/SMBios tables, number of online
cpus, kernel data and command line, etc.
This patch adds support for QEMU fw_cfg interface.
Signed-off-by: Miao Yan
Reviewed-by: Simon Glass
Reviewed-by: Bin Meng
---
Changes in v6:
- fix oneline comment
- do not update bootargs when kernel cmdline only contains '\0'
arch/x86/cpu/qemu/Makefile| 2 +-
arch/x86/cpu/qemu/fw_cfg.c| 283 ++
arch/x86/cpu/qemu/qemu.c | 3 +
arch/x86/include/asm/fw_cfg.h | 93 ++
4 files changed, 380 insertions(+), 1 deletion(-)
create mode 100644 arch/x86/cpu/qemu/fw_cfg.c
create mode 100644 arch/x86/include/asm/fw_cfg.h
diff --git a/arch/x86/cpu/qemu/Makefile b/arch/x86/cpu/qemu/Makefile
index 3f3958a..d613798 100644
--- a/arch/x86/cpu/qemu/Makefile
+++ b/arch/x86/cpu/qemu/Makefile
@@ -7,5 +7,5 @@
ifndef CONFIG_EFI_STUB
obj-y += car.o dram.o
endif
-obj-y += qemu.o
+obj-y += fw_cfg.o qemu.o
obj-$(CONFIG_GENERATE_ACPI_TABLE) += acpi.o dsdt.o
diff --git a/arch/x86/cpu/qemu/fw_cfg.c b/arch/x86/cpu/qemu/fw_cfg.c
new file mode 100644
index 000..0599214
--- /dev/null
+++ b/arch/x86/cpu/qemu/fw_cfg.c
@@ -0,0 +1,283 @@
+/*
+ * (C) Copyright 2015 Miao Yan
+ *
+ * SPDX-License-Identifier:GPL-2.0+
+ */
+
+#include
+#include
+#include
+#include
+#include
+#include
+
+static bool fwcfg_present;
+static bool fwcfg_dma_present;
+
+/* Read configuration item using fw_cfg PIO interface */
+static void qemu_fwcfg_read_entry_pio(uint16_t entry,
+ uint32_t size, void *address)
+{
+ uint32_t i = 0;
+ uint8_t *data = address;
+
+ /*
+* writting FW_CFG_INVALID will cause read operation to resume at
+* last offset, otherwise read will start at offset 0
+*/
+ if (entry != FW_CFG_INVALID)
+ outw(entry, FW_CONTROL_PORT);
+ while (size--)
+ data[i++] = inb(FW_DATA_PORT);
+}
+
+/* Read configuration item using fw_cfg DMA interface */
+static void qemu_fwcfg_read_entry_dma(uint16_t entry,
+ uint32_t size, void *address)
+{
+ struct fw_cfg_dma_access dma;
+
+ dma.length = cpu_to_be32(size);
+ dma.address = cpu_to_be64((uintptr_t)address);
+ dma.control = cpu_to_be32(FW_CFG_DMA_READ);
+
+ /*
+* writting FW_CFG_INVALID will cause read operation to resume at
+* last offset, otherwise read will start at offset 0
+*/
+ if (entry != FW_CFG_INVALID)
+ dma.control |= cpu_to_be32(FW_CFG_DMA_SELECT | (entry << 16));
+
+ barrier();
+
+ debug("qemu_fwcfg_dma_read_entry: addr %p, length %u control 0x%x\n",
+ address, size, be32_to_cpu(dma.control));
+
+ outl(cpu_to_be32((uint32_t)&dma), FW_DMA_PORT_HIGH);
+
+ while (be32_to_cpu(dma.control) & ~FW_CFG_DMA_ERROR)
+ __asm__ __volatile__ ("pause");
+}
+
+static bool qemu_fwcfg_present(void)
+{
+ uint32_t qemu;
+
+ qemu_fwcfg_read_entry_pio(FW_CFG_SIGNATURE, 4, &qemu);
+ return be32_to_cpu(qemu) == QEMU_FW_CFG_SIGNATURE;
+}
+
+static bool qemu_fwcfg_dma_present(void)
+{
+ uint8_t dma_enabled;
+
+ qemu_fwcfg_read_entry_pio(FW_CFG_ID, 1, &dma_enabled);
+ if (dma_enabled & FW_CFG_DMA_ENABLED)
+ return true;
+
+ return false;
+}
+
+static void qemu_fwcfg_read_entry(uint16_t entry,
+ uint32_t length, void *address)
+{
+ if (fwcfg_dma_present)
+ qemu_fwcfg_read_entry_dma(entry, length, address);
+ else
+ qemu_fwcfg_read_entry_pio(entry, length, address);
+}
+
+int qemu_fwcfg_online_cpus(void)
+{
+ uint16_t nb_cpus;
+
+ if (!fwcfg_present)
+ return -ENODEV;
+
+ qemu_fwcfg_read_entry(FW_CFG_NB_CPUS, 2, &nb_cpus);
+
+ return le16_to_cpu(nb_cpus);
+}
+
+/*
+ * This function prepares kernel for zboot. It loads kernel data
+ * to 'load_addr', initrd to 'initrd_addr' and kernel command
+ * line using qemu fw_cfg interface.
+ */
+static int qemu_fwcfg_setup_kernel(void *load_addr, void *initrd_addr)
+{
+ char *data_addr;
+ uint32_t setup_size, kernel_size, cmdline_size, initrd_size;
+
+ qemu_fwcfg_read_entry(FW_CFG_SETUP_SIZE, 4, &setup_size);
+ qemu_fwcfg_read_entry(FW_CFG_KERNEL_SIZE, 4, &kernel_size);
+
+ if (setup_size == 0 || kernel_size == 0) {
+ printf("warning: no kernel available\n");
+ return -1;
+ }
+
+ data_addr = load_addr;
+ qemu_fwcfg_read_entry(FW_CFG_SETUP_DATA,
+ le32_to_cpu(setup_size), data_addr);
+ data_addr += le32_to_cpu(setup_size);
+
+ qemu_fwcfg_read_entry(FW_CFG_KERNEL_DATA,
+ le32_to_cpu(kernel_size), data_addr);
+ data_addr += le32_to_cpu(kernel_size);
+
+ data_addr = initrd_addr;
+ qemu_fw
