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Export (and unexport) reset gpio pin only when not alread exported. #16

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Export (and unexport) reset gpio pin only when not alread exported. #16

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e240b54
Export (and unexport) reset gpio pin only when not alread exported.
Jul 6, 2018
6cd70ba
Merge branch 'kcuzner:master' into master
jmoellers Aug 9, 2021
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51 changes: 38 additions & 13 deletions avrdude/linuxspi.c
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Original file line number Diff line number Diff line change
Expand Up @@ -75,6 +75,8 @@ typedef enum {
#define PDATA(pgm) ((struct pdata *)(pgm->cookie))
#define IMPORT_PDATA(pgm) struct pdata *pdata = PDATA(pgm)

static int need_unexport; /* set to non-0 if we exported the GPIO pin */

/**
* Function Prototypes
*/
Expand Down Expand Up @@ -194,6 +196,20 @@ static int linuxspi_gpio_op_wr(PROGRAMMER* pgm, LINUXSPI_GPIO_OP op, int gpio, c
return 0;
}

/**
* @brief Checks if the given port is already exported
* @param gpio port to check
* @return 0 if port is not exported, non-0 if port is exported
*/
static int linuxspi_gpio_is_exported(int gpio)
{
char path[PATH_MAX];

snprintf(path, PATH_MAX, "/sys/class/gpio/gpio%d", gpio);

return access(path, F_OK) == 0;
}

static void linuxspi_setup(PROGRAMMER* pgm)
{
if ((pgm->cookie = malloc(sizeof(struct pdata))) == 0)
Expand Down Expand Up @@ -225,21 +241,27 @@ static int linuxspi_open(PROGRAMMER* pgm, char* port)
exit(1);
}

//export reset pin
buf = malloc(32);
sprintf(buf, "%d", pgm->pinno[PIN_AVR_RESET] &~PIN_INVERSE);
if (linuxspi_gpio_op_wr(pgm, LINUXSPI_GPIO_EXPORT, pgm->pinno[PIN_AVR_RESET], buf) < 0)
if (!linuxspi_gpio_is_exported(pgm->pinno[PIN_AVR_RESET]))
{
free(buf);
return -1;
need_unexport = 1;

//export reset pin
buf = malloc(32);
sprintf(buf, "%d", pgm->pinno[PIN_AVR_RESET] &~PIN_INVERSE);
if (linuxspi_gpio_op_wr(pgm, LINUXSPI_GPIO_EXPORT, pgm->pinno[PIN_AVR_RESET], buf) < 0)
{
free(buf);
return -1;
}
free(buf);
sleep(1);
}
free(buf);


//set reset to output active and write initial value at same time
//this prevents glitches https://www.kernel.org/doc/Documentation/gpio/sysfs.txt
if (linuxspi_gpio_op_wr(pgm, LINUXSPI_GPIO_DIRECTION, pgm->pinno[PIN_AVR_RESET], pgm->pinno[PIN_AVR_RESET]&PIN_INVERSE ? "high" : "low") < 0)
{
return -1;
return -1;
}

//save the port to our data
Expand All @@ -255,10 +277,13 @@ static void linuxspi_close(PROGRAMMER* pgm)
//set reset to input
linuxspi_gpio_op_wr(pgm, LINUXSPI_GPIO_DIRECTION, pgm->pinno[PIN_AVR_RESET], "in");

//unexport reset
buf = malloc(32);
sprintf(buf, "%d", pgm->pinno[PIN_AVR_RESET]);
linuxspi_gpio_op_wr(pgm, LINUXSPI_GPIO_UNEXPORT, pgm->pinno[PIN_AVR_RESET], buf);
if (need_unexport)
{
//unexport reset
buf = malloc(32);
sprintf(buf, "%d", pgm->pinno[PIN_AVR_RESET]);
linuxspi_gpio_op_wr(pgm, LINUXSPI_GPIO_UNEXPORT, pgm->pinno[PIN_AVR_RESET], buf);
}
}

static void linuxspi_disable(PROGRAMMER* pgm)
Expand Down