emulation/qemu-i440fx: use fw_cfg_dma for fw_cfg_read

- configure DMA fw_cfg
- add support to read using fw_cfg_dma
- provide fw config version id info in logs

BUG=N/A
TEST=Build and boot using qemu-i440fx.

Change-Id: I0be5355b124af40aba62c0840790d46ed0fe80a2
Signed-off-by: Himanshu Sahdev <himanshusah@hcl.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/35365
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>

src/mainboard/emulation/qemu-i440fx/fw_cfg.c

@@ -24,20 +24,29 @@
 
 #define FW_CFG_PORT_CTL       0x0510
 #define FW_CFG_PORT_DATA      0x0511
+#define FW_CFG_DMA_ADDR_HIGH  0x0514
+#define FW_CFG_DMA_ADDR_LOW   0x0518
 
 static int fw_cfg_detected;
+static uint8_t fw_ver;
+
+static void fw_cfg_dma(int control, void *buf, int len);
 
 static int fw_cfg_present(void)
 {
 	static const char qsig[] = "QEMU";
-	unsigned char sig[4];
+	unsigned char sig[FW_CFG_SIG_SIZE];
 	int detected = 0;
 
 	if (fw_cfg_detected == 0) {
 		fw_cfg_get(FW_CFG_SIGNATURE, sig, sizeof(sig));
-		detected = memcmp(sig, qsig, 4) == 0;
+		detected = memcmp(sig, qsig, FW_CFG_SIG_SIZE) == 0;
 		printk(BIOS_INFO, "QEMU: firmware config interface %s\n",
 				detected ? "detected" : "not found");
+		if (detected) {
+			fw_cfg_get(FW_CFG_ID, &fw_ver, sizeof(fw_ver));
+			printk(BIOS_INFO, "Firmware config version id: %d\n", fw_ver);
+		}
 		fw_cfg_detected = detected + 1;
 	}
 	return fw_cfg_detected - 1;
@@ -50,7 +59,10 @@ static void fw_cfg_select(uint16_t entry)
 
 static void fw_cfg_read(void *dst, int dstlen)
 {
-	insb(FW_CFG_PORT_DATA, dst, dstlen);
+	if (fw_ver & FW_CFG_VERSION_DMA)
+		fw_cfg_dma(FW_CFG_DMA_CTL_READ, dst, dstlen);
+	else
+		insb(FW_CFG_PORT_DATA, dst, dstlen);
 }
 
 void fw_cfg_get(uint16_t entry, void *dst, int dstlen)
@@ -500,3 +512,31 @@ void smbios_system_set_uuid(u8 *uuid)
 	fw_cfg_smbios_init();
 	memcpy(uuid, type1_uuid, 16);
 }
+
+/*
+ * Configure DMA setup
+ */
+
+static void fw_cfg_dma(int control, void *buf, int len)
+{
+	volatile FwCfgDmaAccess dma;
+	uintptr_t dma_desc_addr;
+	uint32_t dma_desc_addr_hi, dma_desc_addr_lo;
+
+	dma.control = be32_to_cpu(control);
+	dma.length  = be32_to_cpu(len);
+	dma.address = be64_to_cpu((uintptr_t)buf);
+
+	dma_desc_addr = (uintptr_t)&dma;
+	dma_desc_addr_lo = (uint32_t)(dma_desc_addr & 0xFFFFFFFFU);
+	dma_desc_addr_hi = sizeof(uintptr_t) > sizeof(uint32_t)
+				? (uint32_t)(dma_desc_addr >> 32) : 0;
+
+	// Skip writing high half if unnecessary.
+	if (dma_desc_addr_hi)
+		outl(be32_to_cpu(dma_desc_addr_hi), FW_CFG_DMA_ADDR_HIGH);
+	outl(be32_to_cpu(dma_desc_addr_lo), FW_CFG_DMA_ADDR_LOW);
+
+	while (be32_to_cpu(dma.control) & ~FW_CFG_DMA_CTL_ERROR)
+		;
+}

src/mainboard/emulation/qemu-i440fx/fw_cfg_if.h

@@ -67,11 +67,20 @@ enum fw_cfg_enum {
 
 #define FW_CFG_INVALID          0xffff
 
+/* width in bytes of fw_cfg control register */
+#define FW_CFG_CTL_SIZE         0x02
+
+/* fw_cfg "file name" is up to 56 characters (including terminating nul) */
+#define FW_CFG_MAX_FILE_PATH    56
+
+/* size in bytes of fw_cfg signature */
+#define FW_CFG_SIG_SIZE         4
+
 typedef struct FWCfgFile {
     uint32_t  size;        /* file size */
     uint16_t  select;      /* write this to 0x510 to read it */
     uint16_t  reserved;
-    char      name[56];
+    char      name[FW_CFG_MAX_FILE_PATH];
 } FWCfgFile;
 
 typedef struct FWCfgFiles {
@@ -96,4 +105,26 @@ typedef struct FwCfgSmbios {
 	uint16_t fieldoffset;
 } FwCfgSmbios;
 
+/* FW_CFG_ID bits */
+#define FW_CFG_VERSION          0x01
+#define FW_CFG_VERSION_DMA      0x02
+
+/* FW_CFG_DMA_CONTROL bits */
+#define FW_CFG_DMA_CTL_ERROR    0x01
+#define FW_CFG_DMA_CTL_READ     0x02
+#define FW_CFG_DMA_CTL_SKIP     0x04
+#define FW_CFG_DMA_CTL_SELECT   0x08
+#define FW_CFG_DMA_CTL_WRITE    0x10
+
+#define FW_CFG_DMA_SIGNATURE    0x51454d5520434647ULL /* "QEMU CFG" */
+
+/* Control as first field allows for different structures selected by this
+ * field, which might be useful in the future
+ */
+typedef struct FwCfgDmaAccess {
+	uint32_t control;
+	uint32_t length;
+	uint64_t address;
+} FwCfgDmaAccess;
+
 #endif /* FW_CFG_IF_H */