I believe the only way is to remove them from the main device tree overlay
since that will be loaded before anything else you can do. Decompile the
dtbo, remove the usr led entries in the resulting dts, and recompile to
dtbo (at least this is how it used to work).
On Wed, Aug 13, 2014 at 3:10 PM, Patrick Sheridan <sher...@gmail.com> wrote:
> Hi Brandon,
>
> I'm currently using mmap (in Python) to achieve register wide GPIO. I'm
> concerned though, that the kernel still thinks it owns that memory and
> might inadvertently write to it (for ex: if you forget to disable the
> heartbeat trigger). Do you know of a way to disable the sysfs interface /
> claim those pins as being in use so that you can safely manipulate the mmap
> either through software or a device tree overlay?
>
> Thanks for your help.
>
>
> On Tuesday, July 29, 2014 3:09:08 PM UTC-4, Brandon I wrote:
>>
>> That's still one bit control. There's going to be some unknown time
>> between the bits that will depend on cpu usage. For true 8 bit, you need to
>> use mmap to get a pointer to the gpio control block and modify the
>> registers directly.
>> Each gpio block has 32 pins, and each gpio block has a set and clear
>> register that's 32 bits wide, one bit for each pin. Setting a bit in the
>> set register will set the pin. Setting a bit in the clear register will
>> clear the pin. So, to set 8 pins at once, you would write the 8 bits to the
>> set, then to clear all 8, you would write those 8 bits to the clear
>> register. This will truly be "at once", at least to the capabilities of the
>> hardware.
>>
>> Sysfs has some pretty absurd overhead, so you'll get a few hundred kHz at
>> most. With the the register manipulation using mmap, you'll end up with ~4
>> MHz for a toggle like that.
>>
>>
>> On Sunday, July 27, 2014 4:09:56 AM UTC-7, kthab...@gmail.com wrote:
>>>
>>> /sys/class/gpio/export this driver file i have used.
>>>
>>> but this control only one bit. so, i try to 8bit control like this
>>>
>>> #include "bb_gpio.h"
>>> #include <stdio.h>
>>> #include <sys/time.h>
>>> //#include <string.h>
>>>
>>> void main(void)
>>> {
>>> gpio_export(p9_11); gpio_export(p9_12);
>>> gpio_export(p9_13); gpio_export(p9_14);
>>> gpio_export(p9_15); gpio_export(p9_16);
>>> gpio_export(p9_17); gpio_export(p9_18);
>>>
>>> gpio_direction(p9_11,out); gpio_direction(p9_12,out);
>>> gpio_direction(p9_13,out); gpio_direction(p9_14,out);
>>> gpio_direction(p9_15,out); gpio_direction(p9_16,out);
>>> gpio_direction(p9_17,out); gpio_direction(p9_18,out);
>>> while(1){
>>> pin_write(p9_11,1); pin_write(p9_12,1);
>>> pin_write(p9_13,1); pin_write(p9_14,1);
>>> pin_write(p9_15,1); pin_write(p9_16,1);
>>> pin_write(p9_17,1); pin_write(p9_18,1);
>>> sleep(1);
>>> pin_write(p9_11,0); pin_wirte(p9_12,0);
>>> pin_write(p9_13,0); pin_wirte(p9_14,0);
>>> pin_write(p9_15,0); pin_wirte(p9_16,0);
>>> pin_write(p9_17,0); pin_wirte(p9_18,0);
>>> sleep(1);
>>> };
>>> }
>>>
>>>
>>> ================#include "bb_gpio.h"================
>>>
>>> #ifndef BB_GPIO_H_
>>> #define BB_GPIO_H_
>>>
>>> #include <stdio.h>
>>> #include <string.h>
>>>
>>> /********************************************
>>> * BB_GPIO headerfile
>>> * This file only used to gpio control
>>> * other feature using device-tree-overlay
>>> * when using GPIO, the pin work to MODE7
>>> *=====formula======
>>> * GPIO N1[N2]
>>> * gpio_number = (32 x N1) + N2
>>> *==================
>>> *********************************************/
>>>
>>> #define out 1
>>> #define in 0
>>>
>>> #define export_PATH "/sys/class/gpio/export"
>>> #define value_PATH "/sys/class/gpio/gpio%d/value"
>>> #define direction_PATH "/sys/class/gpio/gpio%d/direction"
>>> #define unexport_PATH "/sys/class/gpio/unexport"
>>>
>>> //*********************P9***********************
>>> #define p9_11 30
>>> #define p9_12 60
>>> #define p9_13 31
>>> #define p9_14 50
>>> #define p9_15 48
>>> #define p9_16 51
>>> #define p9_17 5
>>> #define p9_18 4
>>> //#define p9_19 13
>>> //#define p9_20 12
>>> #define p9_21 3
>>> #define P9_22 2
>>> #define p9_23 49
>>> #define p9_24 15
>>> #define p9_25 117
>>> #define p9_26 14
>>> #define p9_27 115
>>> //#define p9_28 113
>>> //#define p9_29 111
>>> #define p9_30 112
>>> //#define p9_31 110
>>> #define p9_41 20
>>> //#define p9_41 116
>>> //#define p9_42 114
>>> #define p9_42 7
>>> //*********************************************
>>>
>>>
>>> //*********************P8***********************
>>> //*********************************************
>>>
>>>
>>>
>>> //******************function*********************
>>> int gpio_export(int);
>>> int gpio_unexport(int);
>>> int gpio_direction(int, int);
>>> int pin_write(int, int);
>>> int pin_read(int);
>>> //***********************************************
>>>
>>>
>>> #endif /*BB_GPIO_*/
>>>
>>> int gpio_export(int gpio_number)
>>> {
>>> FILE* fp=0;
>>>
>>> if((fp = fopen(export_PATH,"w"))==NULL){
>>> printf("Cannot open export file(>>%s).\n", export_PATH);
>>> return -1;
>>> }
>>> fprintf(fp,"%d",gpio_number);
>>> fclose(fp);
>>> }
>>>
>>> int gpio_unexport(int gpio_number)
>>> {
>>> FILE* fp;
>>>
>>> if((fp = fopen(unexport_PATH,"w"))==NULL){
>>> printf("Cannot open unexport file(>>%s).\n", unexport_PATH);
>>> return -1;
>>> }
>>> fprintf(fp,"%d",gpio_number);
>>> fclose(fp);
>>> }
>>>
>>> int gpio_direction(int gpio_number,int direction)
>>> {
>>> FILE* fp;
>>> char set_value[4]={0};
>>> char dir_path[50]={0};
>>> sprintf(dir_path, direction_PATH, gpio_number);
>>> if((fp = fopen(dir_path,"w"))==NULL){
>>> printf("Cannot open direction file(>>%s).\n",dir_path);
>>> return -1;
>>> }
>>> rewind(fp);
>>> if(direction == out){
>>> strcpy(set_value,"out");
>>> fwrite(&set_value,sizeof(char),3,fp);
>>> fclose(fp);
>>> } else if(direction == in){
>>> strcpy(set_value,"in");
>>> fwrite(&set_value,sizeof(char),2,fp);
>>> fclose(fp);
>>> } else{
>>> printf("invalue pin mode(%d)\n",direction);
>>> return -1;
>>> }
>>> fclose(fp);
>>> return 1;
>>> }
>>>
>>> int pin_write(int gpio_number,int value)
>>> {
>>> FILE* fp;
>>> char val_path[50]={0};
>>> char set_value[2]={0};
>>>
>>> sprintf(val_path, value_PATH, gpio_number);
>>> if((fp = fopen(val_path,"w"))==NULL){
>>> printf("Cannot open value file(>>%s).\n",val_path);
>>> return -1;
>>> }
>>>
>>> rewind(fp);
>>> if(value == 1){
>>> strcpy(set_value,"1");
>>> }
>>> else if(value == 0){
>>> strcpy(set_value,"0");
>>> }
>>> else {
>>> printf("invalid value pin(%d)(%d)\n", gpio_number, value);
>>> return -1;
>>> }
>>>
>>> fwrite(&set_value, sizeof(char), 1, fp);
>>> fclose(fp);
>>> return 0;
>>> }
>>>
>>> int pin_read(int gpio_number)
>>> {
>>> FILE* fp;
>>> int value=0;
>>> char val_path[50]={0};
>>>
>>> sprintf(val_path, value_PATH, gpio_number);
>>> if((fp = fopen(val_path,"r"))==NULL){
>>> printf("Cannot open value file(>>%s).\n",val_path);
>>> return -1;
>>> }
>>>
>>> rewind(fp);
>>> value = fgetc(fp) - '0';
>>> fclose(fp);
>>> return value;
>>> }
>>>
>>>
>>>
>>>
>>> but compile error...
>>>
>>> root@beaglebone:/home/debian/workspace/sources/gpio_control# \
>>> > gcc -o led_blink led_blink.c
>>> /tmp/ccfrwmlk.o: In function `main':
>>> led_blink.c:(.text+0x5c8): undefined reference to `pin_wirte'
>>> led_blink.c:(.text+0x5e0): undefined reference to `pin_wirte'
>>> led_blink.c:(.text+0x5f8): undefined reference to `pin_wirte'
>>> led_blink.c:(.text+0x610): undefined reference to `pin_wirte'
>>> collect2: ld returned 1 exit status
>>> root@beaglebone:/home/debian/workspace/sources/gpio_control#
>>>
>>> i don't know why .. help please
>>>
>> --
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