add i2c readme file

Author: 54shady

README.md

@@ -31,6 +31,8 @@ Codes test on the kernel version below
 
 [HELLO](./debug/hello/README.md)
 
+[I2C](./debug/i2c/README.md)
+
 [REGULATOR (ACT8846 PMU)](./debug/regulator/README.md)
 
 [PLATFORM_DRIVER_TEST](./debug/platform_driver_test/README.md)

debug/i2c/README.md

@@ -0,0 +1,45 @@
+# I2C
+
+## UBOOT 下 I2C
+
+在UBOOT下测试硬件是否正常
+
+确认UBOOT中对I2C支持,一般会有相应命令
+
+	uboot # i2c
+	i2c - I2C sub-system
+
+	Usage:
+	i2c crc32 chip address[.0, .1, .2] count - compute CRC32 checksum
+	i2c dev [dev] - show or set current I2C bus
+	i2c loop chip address[.0, .1, .2] [# of objects] - looping read of device
+	i2c md chip address[.0, .1, .2] [# of objects] - read from I2C device
+	i2c mm chip address[.0, .1, .2] - write to I2C device (auto-incrementing)
+	i2c mw chip address[.0, .1, .2] value [count] - write to I2C device (fill)
+	i2c nm chip address[.0, .1, .2] - write to I2C device (constant address)
+	i2c probe [address] - test for and show device(s) on the I2C bus
+	i2c read chip address[.0, .1, .2] length memaddress - read to memory
+	i2c write memaddress chip address[.0, .1, .2] length - write memory to i2c
+	i2c reset - re-init the I2C Controller
+	i2c speed [speed] - show or set I2C bus speed
+
+查看当前使用的I2C BUS
+
+	uboot # i2c dev
+	Current bus is 0
+
+查询该总线下接的所有I2C设备
+
+	uboot # i2c probe
+	Valid chip addresses: 14 40 41 51 55 5A
+
+	如果是下面这样的输出,则说明该总线有异常,极大可能是有I2C设备拉低了总线
+
+	uboot # i2c probe
+	Valid chip addresses:I2C Send Start Bit Timeout
+	I2C Send Start Bit Timeout
+
+切换I2C BUS
+
+	uboot # i2c dev 1
+	Setting bus to 1

debug/spi/README.md

@@ -16,3 +16,17 @@ read and write test
 
 	cat /dev/ttysWK0
 	echo 1 > /dev/ttysWK0
+
+测试脚本
+
+	i=1
+	while true
+	do
+	if [ $i -eq 10 ]
+	then
+	(( i=1 ))
+	fi
+	echo $i > /dev/ttysWK0
+	sleep 1
+	(( i+=1 ))
+	done