device,sdcard: support write

* To perform a write to the sdcard, the driver will send a command which
  will wait for the busy interrupt. Since the sdcard device and the
  driver are simplified, and there is no interrupt. Therefore the write
  command can not finish completely.
* To fix this issue, we just do not set the use_busy property.

resource/debian/README.md

@@ -50,11 +50,6 @@ apt-get install haveged
 agt-get install sbt
 ```
 
-* 删除登录密码, 登录时输入`root`后可直接登录
-```
-passwd -d root
-```
-
 * 在`/etc/fstab`中添加swap分区
 ```
 /dev/mmcblk0p2 none swap sw 0 0
@@ -65,9 +60,7 @@ passwd -d root
 chmod +w,+x /root
 ```
 
-* 在/root/目录下提前写入所需的测试文件, 如hello.c等. 将来以只读方式挂载时, 无法写入文件.
-
-* 若要创建文件, 可在/run/目录下创建, 它是个tmpfs
+* 在/root/目录下提前写入所需的测试文件, 如hello.c等.
 
 * 在/root/.bashrc中添加如下内容, 可以实现登录后自动运行命令(根据实际情况修改测试的命令):
 ```
@@ -153,3 +146,5 @@ sudo losetup -d /dev/loop0  # 删除loop设备
 
 * 修改`nemu/src/device/sdcard.c`中`init_sdcard()`中打开的镜像文件路径, 即可使用制作的镜像.
 在i9-9900k上测试, 约90s后看到debian的登录提示符.
+
+* 当以可写方式启动镜像是, NEMU遇到错误或通过Ctrl+C直接退出NEMU时, 可能会损坏镜像的崩溃一致性, 此时可以通过fsck命令修复分区.

resource/sdcard/README.md

@@ -2,8 +2,6 @@
 # NEMU sdhost驱动
 
 本驱动裁剪自`linux/drivers/mmc/host/bcm2835.c`, 去除了DMA和中断, 改成直接轮询, 处理器无需支持DMA和中断即可运行.
-不支持写操作, 可以以只读方式启动debian.
-若需要测试文件系统的写操作, 可在启动debian后挂载ramdisk, 在ramdisk上进行写入.
 
 ## 使用方法
 

resource/sdcard/nemu.c

@@ -463,7 +463,7 @@ bool nemu_send_command(struct nemu_host *host, struct mmc_command *cmd)
 			sdcmd |= SDCMD_LONG_RESPONSE;
 		if (cmd->flags & MMC_RSP_BUSY) {
 			sdcmd |= SDCMD_BUSYWAIT;
-			host->use_busy = true;
+			//host->use_busy = true;
 		}
 	}
 

src/device/sdcard.c

@@ -36,6 +36,13 @@ static uint32_t addr = 0;
 static bool write_cmd = 0;
 static bool read_ext_csd = false;
 
+static inline void prepare_rw(int is_write) {
+  blk_addr = base[SDARG];
+  addr = 0;
+  if (fp) fseek(fp, blk_addr << 9, SEEK_SET);
+  write_cmd = is_write;
+}
+
 static void sdcard_io_handler(uint32_t offset, int len, bool is_write) {
   int idx = offset / 4;
   switch (idx) {
@@ -63,21 +70,8 @@ static void sdcard_io_handler(uint32_t offset, int len, bool is_write) {
         case MMC_SET_RELATIVE_ADDR: break;
         case MMC_SELECT_CARD: break;
         case MMC_SET_BLOCK_COUNT: blkcnt = base[SDARG] & 0xffff; break;
-        case MMC_READ_MULTIPLE_BLOCK:
-          // TODO
-          blk_addr = base[SDARG];
-          addr = 0;
-          if (fp) fseek(fp, blk_addr << 9, SEEK_SET);
-          //Log("reading from addr = 0x%lx", blk_addr << 9);
-          write_cmd = false;
-          break;
-        case MMC_WRITE_MULTIPLE_BLOCK:
-          // TODO
-          addr = base[SDARG];
-          if (fp) fseek(fp, addr, SEEK_SET);
-          //Log("writing to addr = 0x%x", base[SDARG]);
-          write_cmd = true;
-          break;
+        case MMC_READ_MULTIPLE_BLOCK: prepare_rw(false); break;
+        case MMC_WRITE_MULTIPLE_BLOCK: prepare_rw(true); break;
         case MMC_SEND_STATUS: base[SDRSP0] = base[SDRSP1] = base[SDRSP2] = base[SDRSP3] = 0; break;
         case MMC_STOP_TRANSMISSION: break;
         default:
@@ -96,7 +90,6 @@ static void sdcard_io_handler(uint32_t offset, int len, bool is_write) {
       break;
     case SDHBLC: break; //Log("@@@@@@@@@@ block count = %d", base[SDHBLC]); break;// only for debug
     case SDDATA:
-       // TODO
        if (read_ext_csd) {
          // See section 8.1 JEDEC Standard JED84-A441
          uint32_t data;
@@ -110,6 +103,7 @@ static void sdcard_io_handler(uint32_t offset, int len, bool is_write) {
        } else if (fp) {
          __attribute__((unused)) int ret;
          if (!write_cmd) { ret = fread(&base[SDDATA], 4, 1, fp); }
+         else { ret = fwrite(&base[SDDATA], 4, 1, fp); }
        }
        addr += 4;
        break;
@@ -129,6 +123,6 @@ void init_sdcard(const char *img) {
 
   Assert(C_SIZE < (1 << 12), "shoule be fit in 12 bits");
 
-  fp = fopen(img, "r");
+  fp = fopen(img, "r+");
   if (fp == NULL) Log("Can not find sdcard image: %s", img);
 }