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c语言spi测试代码,spi_test.c的spi跟踪（spi 数据传送流程）

發布時間：2024/9/27 编程问答 25 豆豆

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晚上跟蹤了下spi_test.c,數據的傳送流程大概是這樣的：

transfer()(spidev_test.c)-->

ioctl()(spidev_test.c)-->

spidev_ioctl()(spidev_test.c)--->

spidev_message()(spidev.c)--->

spidev_sync()(spidev.c)--->

spi_async(spi.h)--通過調用

spi->master->transfer(spi ,message)

調用--->spi_bitbang_transfer()(spi_bitbang.c)--->

bitbang_work()(spi_bitbang.c)--

通過status=bitbang->txrx_buf()

調用---->sep4020_spi_txrx()具體的傳數據，其實是 sep4020_spi_txrx()(spi_sep4020.c)與sep4020_spi_txrx()(spi_sep4020.c)共同實現的，通過硬件上的中斷觸發，完成了數據的傳送

spidev_message()函數：

1：把用戶空間的數據傳進buf；

2：通過spidev_sync()函數一級級調用，來傳輸數據

3：把buf中的數據在送到用戶空間中，通過終端顯示

以下是代碼運行a.out跟蹤代碼

# mount all...........

mount: mounting none on /proc/bus/usb failed: No such file or directory

# Starting mdev.........

starting pid 358, tty '': '-/bin/sh'

hwclock: can't open '/dev/misc/rtc': No such file or directory

mkdir: cannot create directory '/var/run': File exists

/ # ./a.out

after the open-----------------------------------

we have enter the? iocontl*****************

<7>spidev spi0.0: before the setup---------1-------

<7>spidev spi0.0: ---********we enter the sep4020_soi_setupxfer

<7>SPI: sep4020_spi_setupxfer: we get the clk rate? is 176

<7>spidev spi0.0: setting pre-scaler to 176 (hz 500000)

<7>SPI: sep4020_spi_setupxfer: the value of div is 176

<7>SPI: sep4020_spi_setupxfer: the value of BITBANG_CS_INACTIVE is 0

<7>SPI: sep4020_spi_chipsel: we have enter the sep4020_spi_chipsel

<7>spidev spi0.0: sep4020_spi_setup: mode 0, 8 bpw, 500000 hz

<7>spidev spi0.0: spi mode 00

we have enter the? iocontl*****************

after the spi mode----------------------------------

we have enter the? iocontl*****************

<7>spidev spi0.0: before the setup-------------3---

3333333333333333333

<7>spidev spi0.0: ---********we enter the sep4020_soi_setupxfer

<7>SPI: sep4020_spi_setupxfer: we get the clk rate? is 176

<7>spidev spi0.0: setting pre-scaler to 176 (hz 500000)

<7>SPI: sep4020_spi_setupxfer: the value of div is 176

<7>SPI: sep4020_spi_setupxfer: the value of BITBANG_CS_INACTIVE is 0

<7>SPI: sep4020_spi_chipsel: we have enter the sep4020_spi_chipsel

<7>spidev spi0.0: sep4020_spi_setup: mode 0, 8 bpw, 500000 hz

<7>spidev spi0.0: 8 bits per word

we have enter the? iocontl*****************

after the bits per wors-----------------------------

we have enter the? iocontl*****************

<7>spidev spi0.0: before the setup-------------4---

<7>spidev spi0.0: ---********we enter the sep4020_soi_setupxfer

<7>SPI: sep4020_spi_setupxfer: we get the clk rate? is 176

<7>spidev spi0.0: setting pre-scaler to 176 (hz 500000)

<7>SPI: sep4020_spi_setupxfer: the value of div is 176

<7>SPI: sep4020_spi_setupxfer: the value of BITBANG_CS_INACTIVE is 0

<7>SPI: sep4020_spi_chipsel: we have enter the sep4020_spi_chipsel

<7>spidev spi0.0: sep4020_spi_setup: mode 0, 8 bpw, 500000 hz

<7>spidev spi0.0: 500000 Hz (max)

we have enter the? iocontl*****************

after the max speed hz----------------------------------

spi mode: 0

bits per word: 8

max speed: 500000 Hz (500 KHz)

before the transfer iocontl

we have enter the? iocontl*****************

<7>spidev spi0.0: default-------------

--------1--------

---------2-------

--------3--------

--------4--------

--------5--------

--------6--------

we are in spidev_sync -----

********************spi_bitbang_transfer***********************************

********************spi_bitbang_transfer****************end*******************

after the spi_async

*******************bitbang_work***********************************

bitbang_work*******1***********

we enter the sep4020_soi_setupxfer

<7>SPI: sep4020_spi_setupxfer: we get the clk rate? is 176

<7>spidev spi0.0: setting pre-scaler to 176 (hz 500000)

<7>SPI: sep4020_spi_setupxfer: the value of div is 176

bitbang_work*******2***********

<7>SPI: sep4020_spi_chipsel: we have enter the sep4020_spi_chipsel

<7>SPI: sep4020_spi_chipsel: we have enble spi in the sep4020_spi_chipsel

bitbang_work*******3***********

bitbang_work*******4***********

<7>spidev spi0.0: txrx: tx c1c0c000, rx c1c0c000, len 38

<7>SPI: sep4020_spi_txrx: the value of SSIENR is :0x1

<7>SPI: sep4020_spi_txrx: in sep4020_spi_irq before enable spi in txrx

<7>SPI: sep4020_spi_txrx: have enble spi in txrx

<7>SPI: sep4020_spi_txrx: we begin to sent the first byte:0xff

<7>SPI: sep4020_spi_txrx: SSI_IMR:0x1e ,SSI_ISR:0x0 ,SSI_RISR:0x1 ,SSI_SR:0x2

<7>SPI: sep4020_spi_irq: I am done

<7>SPI: sep4020_spi_txrx: the read data is :0

we enter the sep4020_soi_setupxfer

<7>SPI: sep4020_spi_setupxfer: we get the clk rate? is 176

<7>spidev spi0.0: setting pre-scaler to 176 (hz 500000)

<7>SPI: sep4020_spi_setupxfer: the value of div is 176

<7>SPI: sep4020_spi_chipsel: we have enter the sep4020_spi_chipsel

*******************bitbang_work********************end***************

the end of the spidev_sync----

-------7--------

we have after the transfer iocotl----------

FF FF FF FF FF FF

40 00 00 00 00 95

FF FF FF FF FF FF

DE AD BE EF BA AD

BC AC

/ #

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