fix for SPI not loading spidevX.X correctly based on load order

Author: jwcooper

source/c_adc.c

@@ -31,7 +31,6 @@ SOFTWARE.
 #include "common.h"
 
 char adc_prefix_dir[40];
-char ocp_dir[25];
 
 int adc_initialized = 0;
 

source/c_pwm.c

@@ -35,7 +35,6 @@ SOFTWARE.
 #define PERIOD 0
 #define DUTY 1
 
-char ocp_dir[22];
 int pwm_initialized = 0;
 
 // pwm exports

source/common.c

@@ -332,6 +332,31 @@ int build_path(const char *partial_path, const char *prefix, char *full_path, si
     return 0;
 }
 
+int get_spi_bus_path_number(unsigned int spi)
+{
+  char path[50];
+  
+  build_path("/sys/devices", "ocp", ocp_dir, sizeof(ocp_dir));
+
+  if (spi == 0) {
+    snprintf(path, sizeof(path), "%s/48030000.spi/spi_master/spi1", ocp_dir);
+  } else {
+    snprintf(path, sizeof(path), "%s/481a0000.spi/spi_master/spi1", ocp_dir);
+  }
+  
+  DIR* dir = opendir(path);
+  if (dir) {
+    closedir(dir);
+    //device is using /dev/spidev1.x
+    return 1;
+  } else if (ENOENT == errno) {
+    //device is using /dev/spidev2.x
+    return 2;
+  } else {
+    return -1;
+  }
+}
+
 
 int load_device_tree(const char *name)
 {

source/common.h

@@ -41,12 +41,14 @@ int gpio_direction[120];
 int pwm_pins[120];
 
 char ctrl_dir[35];
+char ocp_dir[25];
 
 int get_gpio_number(const char *key, unsigned int *gpio);
 int get_pwm_key(const char *input, char *key);
 int get_adc_ain(const char *key, unsigned int *ain);
 int get_uart_device_tree_name(const char *name, char *dt);
 int build_path(const char *partial_path, const char *prefix, char *full_path, size_t full_path_len);
+int get_spi_bus_path_number(unsigned int spi);
 int load_device_tree(const char *name);
 int unload_device_tree(const char *name);
 int setup_error;

source/spimodule.c

@@ -695,6 +695,7 @@ static PyObject *
 SPI_open(SPI *self, PyObject *args, PyObject *kwds)
 {
 	int bus, device;
+	int bus_path;
 	int max_dt_length = 15;
 	char device_tree_name[max_dt_length];
 	char path[MAXPATH];
@@ -703,7 +704,7 @@ SPI_open(SPI *self, PyObject *args, PyObject *kwds)
 	static char *kwlist[] = {"bus", "device", NULL};
 	if (!PyArg_ParseTupleAndKeywords(args, kwds, "ii:open", kwlist, &bus, &device))
 		return NULL;
-	if (snprintf(device_tree_name, max_dt_length, "ADAFRUIT-SPI%d", bus) >= max_dt_length) {
+	if (snprintf(device_tree_name, max_dt_length, "BB-SPIDEV%d", bus) >= max_dt_length) {
 		PyErr_SetString(PyExc_OverflowError,
 			"Bus and/or device number is invalid.");
 		return NULL;
@@ -713,7 +714,14 @@ SPI_open(SPI *self, PyObject *args, PyObject *kwds)
 		return NULL;
 	}
 
-	if (snprintf(path, MAXPATH, "/dev/spidev%d.%d", bus+1, device) >= MAXPATH) {
+	bus_path = get_spi_bus_path_number(bus);
+	if (bus_path == -1) {
+		PyErr_SetString(PyExc_OverflowError,
+			"Unable to find loaded spi bus path.");
+		return NULL;
+	}
+
+	if (snprintf(path, MAXPATH, "/dev/spidev%d.%d", bus_path, device) >= MAXPATH) {
 		PyErr_SetString(PyExc_OverflowError,
 			"Bus and/or device number is invalid.");
 		return NULL;

test/test_spi.py

@@ -0,0 +1,15 @@
+import pytest
+import os
+
+from Adafruit_BBIO.SPI import SPI
+
+def teardown_module(module):
+    pass
+
+class TestAdc:    
+    def test_spi(self):
+        SPI(1,1)
+
+    def test_setup_spi_wrong_values(self):
+        with pytest.raises(TypeError):   
+            SPI('x', 'x')