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POHow to read and write GPIO values with inb() and outb()
 

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  1. POHow to read and write GPIO values with inb() and outb()
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    <p>I have an atom board with a Fintek F75111 GPIO. I have info from the manufacturer that the SMbus address to access the chip is 06EH.</p> <p>I am trying to read and write values to the GPIO in Linux. I have a sample program from manufacturer written for Windows that looks like this.</p> <pre><code>#include “math.h” #include “stdio.h” #include “dos.h” void main(void){ int SMB_PORT_AD = 0x400; int SMB_DEVICE_ADD = 0x6E; /*75111R’s Add=6eh */ //programming DIO as output //0:input 1:Output /* Index 10, GPIO1x Output pin control */ SMB_Byte_WRITE(SMB_PORT_AD,SMB_DEVICE_ADD,0x10,0xff); delay(10); //programming DIO default LOW /* Index 11, GPIO1x Output Data value */ SMB_Byte_WRITE(SMB_PORT_AD,SMB_DEVICE_ADD,0x11,0x00); delay(10); } unsigned char SMB_Byte_READ (int SMPORT, int DeviceID, int REG_INDEX) { unsigned char SMB_R; outportb(SMPORT+02, 0x00); /* clear */ outportb(SMPORT+00, 0xff); /* clear */ delay(10); outportb(SMPORT+04, DeviceID+1); /* clear */ outportb(SMPORT+03, REG_INDEX); /* clear */ outportb(SMPORT+02, 0x48); /* read_byte */ delay(10); SMB_R= inportb(SMPORT+05); return SMB_R; } void SMB_Byte_WRITE(int SMPORT, int DeviceID, int REG_INDEX, int REG_DATA) { outportb(SMPORT+02, 0x00); /* clear */ outportb(SMPORT+00, 0xff); /* clear */ delay(10); outportb(SMPORT+04, DeviceID); /* clear */ outportb(SMPORT+03, REG_INDEX); /* clear */ outportb(SMPORT+05, REG_DATA); /* read_byte */ outportb(SMPORT+02, 0x48); /* read_byte */ delay(10); } </code></pre> <p>I have tried to translate this to Linux compatible functions inb() and outb() and this is what I got.</p> <pre><code>#include &lt;stdio.h&gt; #include &lt;sys/io.h&gt; unsigned int gpio_read(int PORT, int DEVICE, int REG_INDEX){ unsigned int RESPONSE; outb(0x00, PORT+02); outb(0xff, PORT+00); usleep(100); outb(DEVICE+1, PORT+04); outb(REG_INDEX, PORT+03); outb(0x48, PORT+02); usleep(100); RESPONSE = inb(PORT+05); return RESPONSE; } unsigned int gpio_write(int PORT, int DEVICE, int REG_INDEX, int REG_DATA){ outb(0x00, PORT+02); outb(0xff, PORT+00); usleep(100); outb(DEVICE, PORT+04); outb(REG_INDEX, PORT+03); outb(DATA, PORT+05); outb(0x48, PORT+02); usleep(100); } void main() { int PORT = 0x400; int DEVICE = 0x6E; unsigned int RESPONSE; // Ask access to port from kernel ioperm(0x400, 100, 1); // GPIO1x set to input (0xff is output) gpio_write(PORT, DEVICE, 0x10, 0x00); RESPONSE = gpio_read(PORT, DEVICE, 1); printf("\n %u \n", RESPONSE); } </code></pre> <p>GPIO1X index 0x10 is used to set if the 8 GPIO ports that are connected to GPIO1x are output ports or input ports.</p> <p>Output values for GPIOs are set using the index 0x11, and if the ports work as input ports then index 0x12 is used for reading input values.</p> <p>The problem is that I do not know if this is correct or how to read the values (why the read function outputs something before reading?!?)</p> <p>When I run:</p> <pre><code>RESPONSE = gpio_read(PORT, DEVICE, X); </code></pre> <p>Changing X with values from 1..9 I get this as output: 0 8 8 0 0 0 0 0 0</p> <p>The number 8 confuses me...</p>
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    1. CODid you eventually get this working? I am working on a similar project using the Aaeon Gene-CVO5 board. Unfortunately their Linux support is not so strong. The board uses an Intel 82801G as the i2c master. Using lm-sensors sensors-detect programme I cannot see the F75111 listed.
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