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gpio: Introduce mraa_gpio_init_by_name API

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This commit introduces mraa_gpio_init_by_name API for initializing
a GPIO by its line name provided by the kernel. This feature depends
on the GPIO chardev support and also the line names present in devicetree
or board files. Accessing GPIO using its line name, removes the dependency
from MRAA specific pin mapping and provides a cleaner way to access GPIOs.
This will solve the issue created by an external gpiochip probing before
the SoC's internal gpio controller and thereby making the MRAA pin mapping
wrong.

Currently, this API only supports initializing a single GPIO at a time.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
This commit is contained in:
Manivannan Sadhasivam
2019-05-02 11:09:51 +05:30
committed by Manivannan Sadhasivam
parent 111e6be8f7
commit 0a12c5a017
5 changed files with 186 additions and 24 deletions
Download Patch File Download Diff File Expand all files Collapse all files

116
src/gpio/gpio.c
View File

@@ -163,6 +163,122 @@ init_internal_cleanup:
return dev;
}
mraa_gpio_context
mraa_gpio_init_by_name(char* name)
{
mraa_board_t* board = plat;
mraa_gpio_context dev;
mraa_gpiod_group_t gpio_group;
mraa_gpiod_line_info* linfo = NULL;
mraa_gpiod_chip_info* cinfo;
mraa_gpiod_chip_info** cinfos;
int i, line_found, line_offset;
if (name == NULL) {
syslog(LOG_ERR, "[GPIOD_INTERFACE]: Gpio name not valid");
return NULL;
}
if (!board->chardev_capable) {
syslog(LOG_ERR, "[GPIOD_INTERFACE]: gpio_init_by_name not available for this platform!");
return NULL;
}
dev = (mraa_gpio_context) calloc(1, sizeof(struct _gpio));
if (dev == NULL) {
syslog(LOG_CRIT, "[GPIOD_INTERFACE]: Failed to allocate memory for context");
return NULL;
}
dev->pin_to_gpio_table = malloc(sizeof(int));
if (dev->pin_to_gpio_table == NULL) {
syslog(LOG_CRIT, "[GPIOD_INTERFACE]: Failed to allocate memory for internal member");
mraa_gpio_close(dev);
return NULL;
}
dev->num_chips = mraa_get_chip_infos(&cinfos);
if (dev->num_chips <= 0) {
mraa_gpio_close(dev);
return NULL;
}
/* We are dealing with a single GPIO */
dev->num_pins = 1;
gpio_group = calloc(dev->num_chips, sizeof(struct _gpio_group));
if (gpio_group == NULL) {
syslog(LOG_CRIT, "[GPIOD_INTERFACE]: Failed to allocate memory for internal member");
mraa_gpio_close(dev);
return NULL;
}
dev->gpio_group = gpio_group;
for (i = 0; i < dev->num_chips; ++i) {
gpio_group[i].gpio_chip = i;
gpio_group[i].gpio_lines = NULL;
}
/* Iterate over all gpiochips in the platform to find the requested line */
for_each_gpio_chip(cinfo, cinfos, dev->num_chips)
{
for (i = 0; i < cinfo->chip_info.lines; i++) {
linfo = mraa_get_line_info_by_chip_name(cinfo->chip_info.name, i);
if (!strncmp(linfo->name, name, 32)) {
/* idx is coming from `for_each_gpio_chip` definition */
syslog(LOG_DEBUG, "[GPIOD_INTERFACE]: Chip: %d Line: %d", idx, i);
if (!gpio_group[idx].is_required) {
gpio_group[idx].dev_fd = cinfo->chip_fd;
gpio_group[idx].is_required = 1;
gpio_group[idx].gpiod_handle = -1;
}
/* Map pin to _gpio_group structure. */
dev->pin_to_gpio_table[0] = idx;
gpio_group[idx].gpio_lines = realloc(gpio_group[idx].gpio_lines, sizeof(unsigned int));
gpio_group[idx].gpio_lines[0] = i;
gpio_group[idx].num_gpio_lines++;
line_found = 1;
line_offset = i;
break;
}
}
}
if (!line_found) {
syslog(LOG_ERR, "[GPIOD_INTERFACE]: Gpio not found!");
return NULL;
}
/* Initialize rw_values for read / write multiple functions */
for (i = 0; i < dev->num_chips; ++i) {
gpio_group[i].rw_values = calloc(gpio_group[i].num_gpio_lines, sizeof(unsigned char));
if (gpio_group[i].rw_values == NULL) {
syslog(LOG_CRIT, "[GPIOD_INTERFACE]: Failed to allocate memory for internal member");
mraa_gpio_close(dev);
return NULL;
}
gpio_group[i].event_handles = NULL;
}
/* Save the provided array from the user to our internal structure. */
dev->provided_pins = malloc(dev->num_pins * sizeof(int));
if (dev->provided_pins == NULL) {
syslog(LOG_CRIT, "[GPIOD_INTERFACE]: Failed to allocate memory for internal member");
mraa_gpio_close(dev);
return NULL;
}
memcpy(dev->provided_pins, &line_offset, dev->num_pins * sizeof(int));
dev->events = NULL;
return dev;
}
mraa_gpio_context
mraa_gpio_init(int pin)
{

80
src/gpio/gpio_chardev.c
View File

@@ -22,9 +22,9 @@
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include "gpio/gpio_chardev.h"
#include "linux/gpio.h"
#include "mraa_internal.h"
#include "gpio/gpio_chardev.h"
#include <dirent.h>
#include <errno.h>
@@ -52,7 +52,8 @@ _mraa_free_gpio_groups(mraa_gpio_context dev)
{
mraa_gpiod_group_t gpio_iter;
for_each_gpio_group(gpio_iter, dev) {
for_each_gpio_group(gpio_iter, dev)
{
if (gpio_iter->gpio_lines) {
free(gpio_iter->gpio_lines);
}
@@ -105,7 +106,8 @@ _mraa_close_gpio_event_handles(mraa_gpio_context dev)
{
mraa_gpiod_group_t gpio_iter;
for_each_gpio_group(gpio_iter, dev) {
for_each_gpio_group(gpio_iter, dev)
{
if (gpio_iter->event_handles != NULL) {
for (int j = 0; j < gpio_iter->num_gpio_lines; ++j) {
close(gpio_iter->event_handles[j]);
@@ -124,7 +126,8 @@ _mraa_close_gpio_desc(mraa_gpio_context dev)
{
mraa_gpiod_group_t gpio_iter;
for_each_gpio_group(gpio_iter, dev) {
for_each_gpio_group(gpio_iter, dev)
{
if (gpio_iter->gpiod_handle != -1) {
close(gpio_iter->gpiod_handle);
gpio_iter->gpiod_handle = -1;
@@ -376,56 +379,85 @@ mraa_get_line_values(int line_handle, unsigned int num_lines, unsigned char outp
mraa_boolean_t
mraa_is_gpio_line_kernel_owned(mraa_gpiod_line_info *linfo)
mraa_is_gpio_line_kernel_owned(mraa_gpiod_line_info* linfo)
{
return (linfo->flags & GPIOLINE_FLAG_KERNEL);
}
mraa_boolean_t
mraa_is_gpio_line_dir_out(mraa_gpiod_line_info *linfo)
mraa_is_gpio_line_dir_out(mraa_gpiod_line_info* linfo)
{
return (linfo->flags & GPIOLINE_FLAG_IS_OUT);
}
mraa_boolean_t
mraa_is_gpio_line_active_low(mraa_gpiod_line_info *linfo)
mraa_is_gpio_line_active_low(mraa_gpiod_line_info* linfo)
{
return (linfo->flags & GPIOLINE_FLAG_ACTIVE_LOW);
}
mraa_boolean_t
mraa_is_gpio_line_open_drain(mraa_gpiod_line_info *linfo)
mraa_is_gpio_line_open_drain(mraa_gpiod_line_info* linfo)
{
return (linfo->flags & GPIOLINE_FLAG_OPEN_DRAIN);
}
mraa_boolean_t
mraa_is_gpio_line_open_source(mraa_gpiod_line_info *linfo)
mraa_is_gpio_line_open_source(mraa_gpiod_line_info* linfo)
{
return (linfo->flags & GPIOLINE_FLAG_OPEN_SOURCE);
}
static int
dir_filter(const struct dirent* dir)
{
return !strncmp(dir->d_name, CHIP_DEV_PREFIX, strlen(CHIP_DEV_PREFIX));
}
int
mraa_get_number_of_gpio_chips()
{
int num_chips = 0;
DIR* dev_dir;
struct dirent* dir;
const unsigned int len = strlen(CHIP_DEV_PREFIX);
int num_chips;
struct dirent** dirs;
dev_dir = opendir(DEV_DIR);
if (dev_dir) {
while ((dir = readdir(dev_dir)) != NULL) {
if (!strncmp(dir->d_name, CHIP_DEV_PREFIX, len)) {
num_chips++;
}
}
closedir(dev_dir);
} else {
syslog(LOG_ERR, "[GPIOD_INTERFACE]: opendir() error");
num_chips = scandir("/dev", &dirs, dir_filter, alphasort);
if (num_chips < 0) {
syslog(LOG_ERR, "[GPIOD_INTERFACE]: scandir() error");
return -1;
}
/* Assume opendir() error. */
return num_chips;
}
int
mraa_get_chip_infos(mraa_gpiod_chip_info*** cinfos)
{
int num_chips, i;
struct dirent** dirs;
mraa_gpiod_chip_info** cinfo;
num_chips = scandir("/dev", &dirs, dir_filter, alphasort);
if (num_chips < 0) {
syslog(LOG_ERR, "[GPIOD_INTERFACE]: scandir() error");
return -1;
}
cinfo = (mraa_gpiod_chip_info**) calloc(num_chips, sizeof(mraa_gpiod_chip_info*));
if (!cinfo) {
syslog(LOG_ERR, "[GPIOD_INTERFACE]: Failed to allocate memory for chip info");
return -1;
}
/* Get chip info for all gpiochips present in the platform */
for (i = 0; i < num_chips; i++) {
cinfo[i] = mraa_get_chip_info_by_name(dirs[i]->d_name);
if (!cinfo[i]) {
syslog(LOG_ERR, "[GPIOD_INTERFACE]: invalid chip %s", dirs[i]->d_name);
return 0;
}
}
*cinfos = cinfo;
return num_chips;
}