Add cleanroom document --rebased

flashloaders/cleanroom.md

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+English version can be found below.
+
+# 净室工程文档
+
+代码位于的section：`.text`
+编译制导添加`.syntax unified`
+
+传入参数约定：
+
+参数全部通过寄存器传递
+
+`r0`: 拷贝源点起始地址
+`r1`: 拷贝终点起始地址
+`r2`: 拷贝word（4字节）数(存在例外)
+
+程序功能：将数据从源点拷贝到终点，在拷贝完毕后触发断点以结束执行，结束时`r2`值需清零表明传输完毕。
+
+限制：不可使用栈，可自由使用的临时寄存器为`R3`到`R12`。`R13`为`sp`（stack pointer），`R14`为lr（一般用于储存跳转地址），`R15`为`pc`（program counter）。
+
+要求：每完成一次拷贝，需等待flash完成写入，单次拷贝宽度、检查写入完成的方式见每个文件的具体要求。
+
+特殊地址`flash_base`存放地址需2字节对齐。
+
+## stm32f0.s
+
+例外：`r2`:拷贝half word（2字节）数
+
+特殊地址定义：`flash_base`:定义为0x40022000
+
+`FLASH_CR`: 相对`flash_base`的offset为16
+
+`FLASH_SR`: 相对`flash_base`的offset为12
+
+参考：[https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32f0.h](https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32f0.h)
+[https://www.st.com/resource/en/reference_manual/dm00031936-stm32f0x1stm32f0x2stm32f0x8-advanced-armbased-32bit-mcus-stmicroelectronics.pdf](https://www.st.com/resource/en/reference_manual/dm00031936-stm32f0x1stm32f0x2stm32f0x8-advanced-armbased-32bit-mcus-stmicroelectronics.pdf)
+
+特殊要求：
+每次拷贝开始前需要读出FLASH_CR处的4字节内容，将其最低bit设置为1，写回FLASH_CR。
+
+每次写入数据宽度为2字节（半字）。
+
+每完成一次写入，需等待flash完成写入，检查方式为读取FLASH_SR处4字节内容，若取值为1，则说明写入尚未完成，需继续轮询等待；否则需要检查FLASH_SR处值是否为4，若是4，则应直接准备退出。
+
+退出：全部拷贝执行完毕后触发断点前，将FLASH_CR处4字节内容最低bit清为0，写回FLASH_CR。
+
+
+
+## stm32f4.s
+
+特殊地址定义： `flash_base`：定义为0x40023c00
+
+`FLASH_SR`:相对flash_base的offset为0xe（14）
+
+参考：[https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32f4.h](https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32f4.h)
+[https://www.st.com/content/ccc/resource/technical/document/reference_manual/3d/6d/5a/66/b4/99/40/d4/DM00031020.pdf/files/DM00031020.pdf/jcr:content/translations/en.DM00031020.pdf](https://www.st.com/content/ccc/resource/technical/document/reference_manual/3d/6d/5a/66/b4/99/40/d4/DM00031020.pdf/files/DM00031020.pdf/jcr:content/translations/en.DM00031020.pdf)
+
+特殊要求：
+
+每次写入的数据宽度为4字节（字）。
+
+每完成一次写入，需等待flash完成写入，检查方式为读取FLASH_SR处2字节内容，若取值为1，则说明写入尚未完成，需继续轮询等待。
+
+## stm32f4lv.s
+
+特殊地址定义：`flash_base`：定义为0x40023c00
+
+`FLASH_SR`:相对`flash_base`的offset为0xe (14)
+
+参考：[https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32f4.h](https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32f4.h)
+[https://www.st.com/content/ccc/resource/technical/document/reference_manual/3d/6d/5a/66/b4/99/40/d4/DM00031020.pdf/files/DM00031020.pdf/jcr:content/translations/en.DM00031020.pdf](https://www.st.com/content/ccc/resource/technical/document/reference_manual/3d/6d/5a/66/b4/99/40/d4/DM00031020.pdf/files/DM00031020.pdf/jcr:content/translations/en.DM00031020.pdf)
+
+特殊要求：
+
+每次写入的数据宽度为1字节（1/4字）。
+
+每完成一次写入，需等待flash完成写入，检查方式为读取FLASH_SR处2字节内容，若取值为1，则说明写入尚未完成，需继续轮询等待。
+
+## stm32f7.s
+
+参考：[https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32f7.h](https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32f7.h)
+[https://www.st.com/resource/en/reference_manual/dm00124865-stm32f75xxx-and-stm32f74xxx-advanced-armbased-32bit-mcus-stmicroelectronics.pdf](https://www.st.com/resource/en/reference_manual/dm00124865-stm32f75xxx-and-stm32f74xxx-advanced-armbased-32bit-mcus-stmicroelectronics.pdf)
+
+要求同stm32f4.s，额外要求在每次拷贝执行完毕、flash写入成功检测前，执行`dsb sy`指令以建立内存屏障。
+
+
+## stm32f7lv.s
+
+参考：[https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32f7.h](https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32f7.h)
+[https://www.st.com/resource/en/reference_manual/dm00124865-stm32f75xxx-and-stm32f74xxx-advanced-armbased-32bit-mcus-stmicroelectronics.pdf](https://www.st.com/resource/en/reference_manual/dm00124865-stm32f75xxx-and-stm32f74xxx-advanced-armbased-32bit-mcus-stmicroelectronics.pdf)
+要求基本同stm32f7.s，差异要求为每次写入的数据宽度为1字节（1/4字）。
+
+## stm32l0x.s
+
+特殊要求：
+
+每次写入的数据宽度为4字节（字）
+
+无需实现检查flash写入完成功能
+
+## stm32l4.s
+
+例外：`r2`： 拷贝双字（8字节）数
+
+特殊地址定义：`flash_base`: 0x40022000
+
+`FLASH_BSY`：相对flash_base的offset为0x12
+
+参考：[https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32l4.h](https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32l4.h)
+[https://www.st.com/resource/en/reference_manual/dm00310109-stm32l4-series-advanced-armbased-32bit-mcus-stmicroelectronics.pdf](https://www.st.com/resource/en/reference_manual/dm00310109-stm32l4-series-advanced-armbased-32bit-mcus-stmicroelectronics.pdf)
+
+拷贝方式：一次性拷贝连续的8个字节（使用两个连续寄存器作中转）并写入
+
+每完成一次写入，需等待flash完成写入，检查方式为读取FLASH_BSY处半字（2字节），若其最低位非1，可继续拷贝。
+
+## stm32lx.s
+
+要求与stm32l0x.s相同
+
+# Clean Room Documentation English Version
+
+Code is situated in section `.text`
+
+Shall add a compile directive at the head: `.syntax unified`
+
+**Calling convention**:
+
+All parameters would be passed over registers
+
+`r0`: the base address of the copy source
+`r1`: the base address of the copy destination
+`r2`: the total word (4 bytes) count to be copied (with expeptions)
+
+**What the program is expected to do**:
+
+Copy data from source to destination, after which trigger a breakpint to exit. Before exit, `r2` must be cleared to zero to indicate that the copy is done.
+
+**Limitation**: No stack operations are permitted. Registers ranging from `r3` to `r12` are free to use. Note that `r13` is `sp`(stack pointer), `r14` is `lr`(commonly used to store jump address), `r15` is `pc`(program counter).
+
+**Requirement**: After every single copy, wait until the flash finishes. The detailed single copy length and the way to check can be found below. Address of `flash_base` shall be two-bytes aligned.
+
+## stm32f0.s
+
+**Exception**: `r2` stores the total half word (2 bytes) count to be copied
+
+`flash_base`: 0x40022000
+
+`FLASH_CR`: offset from `flash_base` is 16
+
+`FLASH_SR`: offset from `flash_base` is 12
+
+**Reference**: [https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32f0.h](https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32f0.h)
+[https://www.st.com/resource/en/reference_manual/dm00031936-stm32f0x1stm32f0x2stm32f0x8-advanced-armbased-32bit-mcus-stmicroelectronics.pdf](https://www.st.com/resource/en/reference_manual/dm00031936-stm32f0x1stm32f0x2stm32f0x8-advanced-armbased-32bit-mcus-stmicroelectronics.pdf)
+
+**Special requirements**:
+
+Before every copy, read a word from FLASH_CR, set the lowest bit to 1 and write back. Copy one half word each time.
+
+How to wait for the write process: read a word from FLASH_SR, loop until the content is not 1. After that, check FLASH_SR, proceed if the content is not 4, otherwise exit.
+
+Exit: after the copying process and before triggering the breakpoint, clear the lowest bit in FLASH_CR.
+
+## stm32f4.s
+
+`flash_base`: 0x40023c00
+
+`FLASH_SR`: offset from `flash_base` is 0xe (14)
+
+**Reference**: [https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32f4.h](https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32f4.h)
+[https://www.st.com/content/ccc/resource/technical/document/reference_manual/3d/6d/5a/66/b4/99/40/d4/DM00031020.pdf/files/DM00031020.pdf/jcr:content/translations/en.DM00031020.pdf](https://www.st.com/content/ccc/resource/technical/document/reference_manual/3d/6d/5a/66/b4/99/40/d4/DM00031020.pdf/files/DM00031020.pdf/jcr:content/translations/en.DM00031020.pdf)
+
+
+**Special requirements**:
+
+Copy one word each time.
+How to wait for the write process: read a half word from FLASH_SR, loop until the content is not 1.
+
+## stm32f4lv.s
+
+`flash_base`: 0x40023c00
+
+`FLASH_SR`: offset from `flash_base` is 0xe (14)
+
+**Reference**: [https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32f4.h](https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32f4.h)
+[https://www.st.com/content/ccc/resource/technical/document/reference_manual/3d/6d/5a/66/b4/99/40/d4/DM00031020.pdf/files/DM00031020.pdf/jcr:content/translations/en.DM00031020.pdf](https://www.st.com/content/ccc/resource/technical/document/reference_manual/3d/6d/5a/66/b4/99/40/d4/DM00031020.pdf/files/DM00031020.pdf/jcr:content/translations/en.DM00031020.pdf)
+
+**Special Requirements**:
+
+Copy one byte each time.
+
+How to wait from the write process: read a half word from FLASH_SR, loop until the content is not 1.
+
+## stm32f7.s
+
+**Reference**: [https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32f7.h](https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32f7.h)
+[https://www.st.com/resource/en/reference_manual/dm00124865-stm32f75xxx-and-stm32f74xxx-advanced-armbased-32bit-mcus-stmicroelectronics.pdf](https://www.st.com/resource/en/reference_manual/dm00124865-stm32f75xxx-and-stm32f74xxx-advanced-armbased-32bit-mcus-stmicroelectronics.pdf)
+
+Mostly same with `stm32f4.s`. Require establishing a memory barrier after every copy and before checking for finished writing by `dsb sy`
+
+## stm32f7lv.s
+
+**Reference**: [https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32f7.h](https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32f7.h)
+[https://www.st.com/resource/en/reference_manual/dm00124865-stm32f75xxx-and-stm32f74xxx-advanced-armbased-32bit-mcus-stmicroelectronics.pdf](https://www.st.com/resource/en/reference_manual/dm00124865-stm32f75xxx-and-stm32f74xxx-advanced-armbased-32bit-mcus-stmicroelectronics.pdf)
+
+**Special Requirements**:
+
+Mostly same with `stm32f7.s`. Copy one byte each time.
+
+## stm32l0x.s
+
+**Special Requirements**:
+
+Copy one word each time. No wait for write.
+
+## stm32l4.s
+
+**Exception**: r2 stores the double word count to be copied.
+
+`flash_base`: 0x40022000
+`FLASH_BSY`: offset from `flash_base` is 0x12
+
+**Reference**: [https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32l4.h](https://chromium.googlesource.com/chromiumos/platform/ec/+/master/chip/stm32/registers-stm32l4.h)
+[https://www.st.com/resource/en/reference_manual/dm00310109-stm32l4-series-advanced-armbased-32bit-mcus-stmicroelectronics.pdf](https://www.st.com/resource/en/reference_manual/dm00310109-stm32l4-series-advanced-armbased-32bit-mcus-stmicroelectronics.pdf)
+
+**Special Requirements**:
+
+Copy one double word each time (More than one registers are allowed).
+
+How to wait for the write process: read a half word from `FLASH_BSY`, loop until the lowest bit turns non-1.
+
+## stm32lx.s
+
+Same with stm32l0x.s.