gpio: Add gpio chardev interface

Signed-off-by: Mihai Stefanescu <mihai.t.gh.stefanescu@gmail.com>
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>

api/mraa/gpio.h

@@ -61,7 +61,10 @@ typedef enum {
     MRAA_GPIO_STRONG = 0,   /**< Default. Strong high and low */
     MRAA_GPIO_PULLUP = 1,   /**< Resistive High */
     MRAA_GPIO_PULLDOWN = 2, /**< Resistive Low */
-    MRAA_GPIO_HIZ = 3       /**< High Z State */
+    MRAA_GPIO_HIZ = 3,      /**< High Z State */
+    MRAA_GPIOD_ACTIVE_LOW = 4,
+    MRAA_GPIOD_OPEN_DRAIN = 5,
+    MRAA_GPIOD_OPEN_SOURCE = 6,
 } mraa_gpio_mode_t;
 
 /**
@@ -109,6 +112,8 @@ typedef enum {
  */
 mraa_gpio_context mraa_gpio_init(int pin);
 
+mraa_gpio_context mraa_gpio_init_multiple(int pins[], int num_pins);
+
 /**
  * Initialise gpio context without any mapping to a pin
  *
@@ -126,6 +131,8 @@ mraa_gpio_context mraa_gpio_init_raw(int gpiopin);
  */
 mraa_result_t mraa_gpio_edge_mode(mraa_gpio_context dev, mraa_gpio_edge_t mode);
 
+mraa_result_t mraa_gpio_edge_mode_multiple(mraa_gpio_context dev, mraa_gpio_edge_t mode);
+
 /**
  * Set an interrupt on pin
  *
@@ -138,6 +145,8 @@ mraa_result_t mraa_gpio_edge_mode(mraa_gpio_context dev, mraa_gpio_edge_t mode);
  */
 mraa_result_t mraa_gpio_isr(mraa_gpio_context dev, mraa_gpio_edge_t edge, void (*fptr)(void*), void* args);
 
+mraa_result_t mraa_gpio_isr_multiple(mraa_gpio_context dev, mraa_gpio_edge_t edge, void (*fptr)(void*), void* args);
+
 /**
  * Stop the current interrupt watcher on this Gpio, and set the Gpio edge mode
  * to MRAA_GPIO_EDGE_NONE
@@ -165,6 +174,8 @@ mraa_result_t mraa_gpio_mode(mraa_gpio_context dev, mraa_gpio_mode_t mode);
  */
 mraa_result_t mraa_gpio_dir(mraa_gpio_context dev, mraa_gpio_dir_t dir);
 
+mraa_result_t mraa_gpio_dir_multiple(mraa_gpio_context dev, mraa_gpio_dir_t dir);
+
 /**
  * Read Gpio direction
  *
@@ -183,6 +194,8 @@ mraa_result_t mraa_gpio_read_dir(mraa_gpio_context dev, mraa_gpio_dir_t *dir);
  */
 mraa_result_t mraa_gpio_close(mraa_gpio_context dev);
 
+mraa_result_t mraa_gpio_close_multiple(mraa_gpio_context dev);
+
 /**
  * Read the Gpio value. This can be 0 or 1. A resonse of -1 means that there
  * was a fatal error.
@@ -192,6 +205,11 @@ mraa_result_t mraa_gpio_close(mraa_gpio_context dev);
  */
 int mraa_gpio_read(mraa_gpio_context dev);
 
+/* Values array is provided by user. Must be the same size as the array passed in init.
+ * It will be overwritten with the read results.
+ */
+mraa_result_t mraa_gpio_read_multiple(mraa_gpio_context dev, int output_values[]);
+
 /**
  * Write to the Gpio Value.
  *
@@ -201,6 +219,8 @@ int mraa_gpio_read(mraa_gpio_context dev);
  */
 mraa_result_t mraa_gpio_write(mraa_gpio_context dev, int value);
 
+mraa_result_t mraa_gpio_write_multiple(mraa_gpio_context dev, int input_values[]);
+
 /**
  * Change ownership of the context.
  *

include/mraa_internal_types.h

@@ -106,6 +106,26 @@ struct _firmata {
 };
 #endif
 
+struct _gpio_group {
+    int is_required;
+    int dev_fd;
+    int gpiod_handle;
+    unsigned int gpio_chip;
+    /* We can have multiple lines in a gpio group. */
+    unsigned int num_gpio_lines;
+    unsigned int *gpio_lines;
+
+    /* R/W stuff.*/
+    unsigned char *rw_values;
+    /* Reverse mapping to original pin number indexes. */
+    unsigned int *gpio_group_to_pins_table;
+
+    unsigned int flags;
+
+    /* Event specific fields. */
+    int *event_handles;
+};
+
 /**
  * A structure representing a gpio pin.
  */
@@ -134,8 +154,30 @@ struct _gpio {
 #ifdef PERIPHERALMAN
     AGpio *bgpio;
 #endif
+
+    /* TODO: The below members should be integrated in gpio_group struct. */
+    int dev_fd;
+    int gpiod_handle;
+    unsigned int gpio_chip;
+    unsigned int gpio_line;
+
+    /* Multiple gpio support. These members are treated separately for now until multiple gpio support is accepted. */
+    unsigned int num_chips;
+    struct _gpio_group *gpio_group;
+    /* Pin index passed by the user to gpio_group structures. */
+    int *pin_to_gpio_table;
+    unsigned int num_pins;
+
+    struct _gpio *next;
 };
 
+/* Macro for looping over gpio chips. */
+#define for_each_gpio_group(group, dev) \
+    for (int k = 0; \
+        k < dev->num_chips && (group = &dev->gpio_group[k]); \
+        ++k) \
+            if (dev->gpio_group[k].is_required)
+
 /**
  * A structure representing a I2C bus
  */
@@ -315,6 +357,10 @@ typedef struct {
     mraa_mux_t mux[6]; /** Array holding information about mux */
     unsigned int output_enable; /** Output Enable GPIO, for level shifting */
     mraa_pin_cap_complex_t complex_cap;
+
+    /* GPIOD_INTERFACE */
+    unsigned int gpio_chip;
+    unsigned int gpio_line;
     /*@}*/
 } mraa_pin_t;
 
@@ -447,6 +493,7 @@ typedef struct _board_t {
     mraa_pininfo_t* pins;     /**< Pointer to pin array */
     mraa_adv_func_t* adv_func;    /**< Pointer to advanced function disptach table */
     struct _board_t* sub_platform;     /**< Pointer to sub platform */
+    mraa_boolean_t chardev_capable;  /**< Decide what interface is being used: old sysfs or new char device*/
     /*@}*/
 } mraa_board_t;
 

src/mraa.c

@@ -45,7 +45,7 @@
 #include <unistd.h>
 #include <ctype.h>
 #include <limits.h>
-
+#include <sys/utsname.h>
 
 #if defined(IMRAA)
 #include <json-c/json.h>
@@ -98,6 +98,57 @@ mraa_set_log_level(int level)
     return MRAA_ERROR_INVALID_PARAMETER;
 }
 
+mraa_boolean_t mraa_is_kernel_chardev_interface_compatible()
+{
+    struct utsname buf;
+    int status;
+
+    status = uname(&buf);
+
+    if (status) {
+        syslog(LOG_ERR, "uname() error");
+        return 0;
+    }
+
+    int major, minor;
+    char *token;
+
+    token = strtok(buf.release, ".");
+    if (token == NULL) {
+        syslog(LOG_ERR, "Could not find kernel version major number");
+        return 0;
+    }
+    status = mraa_atoi(token, &major);
+    if (status) {
+        syslog(LOG_ERR, "mraa_atoi() error");
+        return 0;
+    }
+
+    token = strtok(NULL, ".");
+    if (token == NULL) {
+        syslog(LOG_ERR, "Could not find kernel version minor number");
+        return 0;
+    }
+    status = mraa_atoi(token, &minor);
+    if (status) {
+        syslog(LOG_ERR, "mraa_atoi() error");
+        return 0;
+    }
+
+    if (major < 4 || minor < 8) {
+        syslog(LOG_ERR, "Kernel version %i.%i not supported for chardev interface. Need version 4.8 or newer!", major, minor);
+        return 0;
+    }
+
+    return 1;
+}
+
+/* TODO: Add all relevant checks here and return the overall result. */
+mraa_boolean_t mraa_is_platform_chardev_interface_capable()
+{
+    return mraa_is_kernel_chardev_interface_compatible();
+}
+
 /**
  * Whilst the actual mraa init function is now called imraa_init, it's only
  * callable externally if IMRAA is enabled
@@ -218,6 +269,11 @@ imraa_init()
         return MRAA_ERROR_NO_RESOURCES;
     }
 
+    plat->chardev_capable = mraa_is_platform_chardev_interface_capable();
+    if (plat->chardev_capable) {
+        syslog(LOG_NOTICE, "libmraa: support for chardev interface is activated");
+    }
+
     syslog(LOG_NOTICE, "libmraa initialised for platform '%s' of type %d", mraa_get_platform_name(), mraa_get_platform_type());
     return MRAA_SUCCESS;
 }