[RFC PATCH v4 1/2] hw/riscv: sifive_u: Add backend drive support

[Green Wan]

Add '-drive' support to OTP device. Allow users to assign a raw file
as OTP image.

Signed-off-by: Green Wan <green....@sifive.com>
---
 hw/riscv/sifive_u_otp.c         | 50 +++++++++++++++++++++++++++++++++
 include/hw/riscv/sifive_u_otp.h |  2 ++
 2 files changed, 52 insertions(+)

diff --git a/hw/riscv/sifive_u_otp.c b/hw/riscv/sifive_u_otp.c
index f6ecbaa2ca..aab2220494 100644
--- a/hw/riscv/sifive_u_otp.c
+++ b/hw/riscv/sifive_u_otp.c
@@ -24,6 +24,8 @@
 #include "qemu/log.h"
 #include "qemu/module.h"
 #include "hw/riscv/sifive_u_otp.h"
+#include "sysemu/blockdev.h"
+#include "sysemu/block-backend.h"
 
 static uint64_t sifive_u_otp_read(void *opaque, hwaddr addr, unsigned int size)
 {
@@ -46,6 +48,16 @@ static uint64_t sifive_u_otp_read(void *opaque, hwaddr addr, 
unsigned int size)
         if ((s->pce & SIFIVE_U_OTP_PCE_EN) &&
             (s->pdstb & SIFIVE_U_OTP_PDSTB_EN) &&
             (s->ptrim & SIFIVE_U_OTP_PTRIM_EN)) {
+
+            /* read from backend */
+            if (s->blk) {
+                int32_t buf;
+
+                blk_pread(s->blk, s->pa * SIFIVE_U_OTP_FUSE_WORD, &buf,
+                          SIFIVE_U_OTP_FUSE_WORD);
+                return buf;
+            }
+
             return s->fuse[s->pa & SIFIVE_U_OTP_PA_MASK];
         } else {
             return 0xff;
@@ -123,6 +135,12 @@ static void sifive_u_otp_write(void *opaque, hwaddr addr,
         s->ptrim = val32;
         break;
     case SIFIVE_U_OTP_PWE:
+        /* write to backend */
+        if (s->blk) {
+            blk_pwrite(s->blk, s->pa * SIFIVE_U_OTP_FUSE_WORD, &val32,
+                       SIFIVE_U_OTP_FUSE_WORD, 0);
+        }
+
         s->pwe = val32;
         break;
     default:
@@ -143,16 +161,48 @@ static const MemoryRegionOps sifive_u_otp_ops = {
 
 static Property sifive_u_otp_properties[] = {
     DEFINE_PROP_UINT32("serial", SiFiveUOTPState, serial, 0),
+    DEFINE_PROP_DRIVE("drive", SiFiveUOTPState, blk),
     DEFINE_PROP_END_OF_LIST(),
 };
 
 static void sifive_u_otp_realize(DeviceState *dev, Error **errp)
 {
     SiFiveUOTPState *s = SIFIVE_U_OTP(dev);
+    DriveInfo *dinfo;
 
     memory_region_init_io(&s->mmio, OBJECT(dev), &sifive_u_otp_ops, s,
                           TYPE_SIFIVE_U_OTP, SIFIVE_U_OTP_REG_SIZE);
     sysbus_init_mmio(SYS_BUS_DEVICE(dev), &s->mmio);
+
+    dinfo = drive_get_next(IF_NONE);
+    if (dinfo) {
+        int ret;
+        uint64_t perm;
+        int filesize;
+        BlockBackend *blk;
+
+        blk = blk_by_legacy_dinfo(dinfo);
+        filesize = SIFIVE_U_OTP_NUM_FUSES * SIFIVE_U_OTP_FUSE_WORD;
+        if (blk_getlength(blk) < filesize) {
+            qemu_log_mask(LOG_GUEST_ERROR, "OTP drive size < 16K\n");
+            return;
+        }
+
+        qdev_prop_set_drive(dev, "drive", blk);
+
+        perm = BLK_PERM_CONSISTENT_READ |
+                        (blk_is_read_only(s->blk) ? 0 : BLK_PERM_WRITE);
+        ret = blk_set_perm(s->blk, perm, BLK_PERM_ALL, errp);
+        if (ret < 0) {
+            qemu_log_mask(LOG_GUEST_ERROR, "set perm error.");
+        }
+
+        if (blk_pread(s->blk, 0, s->fuse, filesize) != filesize) {
+            qemu_log_mask(LOG_GUEST_ERROR,
+                          "failed to read the initial flash content");
+            return;
+        }
+    }
 }
 
 static void sifive_u_otp_reset(DeviceState *dev)
diff --git a/include/hw/riscv/sifive_u_otp.h b/include/hw/riscv/sifive_u_otp.h
index 639297564a..13d2552e43 100644
--- a/include/hw/riscv/sifive_u_otp.h
+++ b/include/hw/riscv/sifive_u_otp.h
@@ -43,6 +43,7 @@
 
 #define SIFIVE_U_OTP_PA_MASK        0xfff
 #define SIFIVE_U_OTP_NUM_FUSES      0x1000
+#define SIFIVE_U_OTP_FUSE_WORD      4
 #define SIFIVE_U_OTP_SERIAL_ADDR    0xfc
 
 #define SIFIVE_U_OTP_REG_SIZE       0x1000
@@ -75,6 +76,7 @@ typedef struct SiFiveUOTPState {
     uint32_t fuse[SIFIVE_U_OTP_NUM_FUSES];
     /* config */
     uint32_t serial;
+    BlockBackend *blk;
 } SiFiveUOTPState;
 
 #endif /* HW_SIFIVE_U_OTP_H */
-- 
2.17.1