[v1.05][ARM] Add support to detect SoC from PCI (#245) with initial support for NVIDIA Tegra

src/common/pci.c

@@ -0,0 +1,178 @@
+#define _GNU_SOURCE
+
+#include <sys/stat.h>
+#include <dirent.h>
+
+#include "udev.h"
+#include "global.h"
+#include "pci.h"
+
+#ifndef PATH_MAX
+  #define PATH_MAX 1024
+#endif
+
+#define PCI_PATH "/sys/bus/pci/devices/"
+#define MAX_LENGTH_PCI_DIR_NAME 1024
+
+/*
+ * doc: https://wiki.osdev.org/PCI#Class_Codes
+ *      https://pci-ids.ucw.cz/read/PC
+ */
+#define PCI_VENDOR_ID_AMD    0x1002
+#define CLASS_VGA_CONTROLLER 0x0300
+#define CLASS_3D_CONTROLLER  0x0302
+
+// Return a list of PCI devices containing only
+// the sysfs path
+struct pci_devices * get_pci_paths(void) {
+  DIR *dirp;
+
+  if ((dirp = opendir(PCI_PATH)) == NULL) {
+    perror("opendir");
+    return NULL;
+  }
+
+  struct dirent *dp;
+  int numDirs = 0;  
+  errno = 0;
+
+  while ((dp = readdir(dirp)) != NULL) {
+    if (strcmp(dp->d_name, ".") != 0 && strcmp(dp->d_name, "..") != 0)
+      numDirs++;
+  }  
+  if (errno != 0) {
+    perror("readdir");
+    return NULL;
+  }
+
+  rewinddir(dirp);
+
+  struct pci_devices * pci = emalloc(sizeof(struct pci_devices));
+  pci->num_devices = numDirs;
+  pci->devices = emalloc(sizeof(struct pci_device) * pci->num_devices);
+  char * full_path = emalloc(PATH_MAX * sizeof(char));
+  struct stat stbuf;
+  int i = 0;
+
+  while ((dp = readdir(dirp)) != NULL) {
+    if (strcmp(dp->d_name, ".") == 0 || strcmp(dp->d_name, "..") == 0)
+      continue;
+
+    if (strlen(dp->d_name) > MAX_LENGTH_PCI_DIR_NAME) {
+      printErr("Directory name is too long: %s", dp->d_name);
+      return NULL;
+    }
+
+    memset(full_path, 0, PATH_MAX * sizeof(char));
+    snprintf(full_path, min(strlen(PCI_PATH) + strlen(dp->d_name) + 1, PATH_MAX), "%s%s", PCI_PATH, dp->d_name);    
+
+    if (stat(full_path, &stbuf) == -1) {
+      perror("stat");
+      return NULL;
+    }
+
+    if ((stbuf.st_mode & S_IFMT) == S_IFDIR) {
+      int strLen = min(MAX_LENGTH_PCI_DIR_NAME, strlen(dp->d_name)) + 1;
+      pci->devices[i] = emalloc(sizeof(struct pci_device));
+      pci->devices[i]->path = ecalloc(sizeof(char), strLen);
+      strncpy(pci->devices[i]->path, dp->d_name, strLen);
+      i++;
+    }        
+  }
+  if (errno != 0) {
+    perror("readdir");
+    return NULL;
+  }
+
+  return pci;
+}
+
+// For each PCI device in the list pci, fetch its vendor and 
+// device id using sysfs (e.g., /sys/bus/pci/devices/XXX/{vendor/device})
+void populate_pci_devices(struct pci_devices * pci) {
+  int filelen;
+  char* buf;
+
+  for (int i=0; i < pci->num_devices; i++) {
+    struct pci_device* dev = pci->devices[i];
+    int path_size = strlen(PCI_PATH) + strlen(dev->path) + 2;
+
+    // Read vendor_id
+    char *vendor_id_path = emalloc(sizeof(char) * (path_size + strlen("vendor")));
+    sprintf(vendor_id_path, "%s/%s/%s", PCI_PATH, dev->path, "vendor");
+    
+    if ((buf = read_file(vendor_id_path, &filelen)) == NULL) {
+      printWarn("read_file: %s: %s\n", vendor_id_path, strerror(errno));
+      dev->vendor_id = 0;
+    }
+    else {
+      dev->vendor_id = strtol(buf, NULL, 16);
+    }
+
+    // Read device_id
+    char *device_id_path = emalloc(sizeof(char) * (path_size + strlen("device")));
+    sprintf(device_id_path, "%s/%s/%s", PCI_PATH, dev->path, "device");
+
+    if ((buf = read_file(device_id_path, &filelen)) == NULL) {
+      printWarn("read_file: %s: %s\n", device_id_path, strerror(errno));
+      dev->device_id = 0;
+    }
+    else {
+      dev->device_id = strtol(buf, NULL, 16);
+    }
+
+    free(vendor_id_path);
+    free(device_id_path);
+  }
+}
+
+// Right now, we are interested in PCI devices which
+// vendor is NVIDIA (to be extended in the future).
+// Should we also restrict to VGA controllers only?
+bool pci_device_is_useful(struct pci_device* dev) {
+  return dev->vendor_id == PCI_VENDOR_NVIDIA;
+}
+
+// Filter the input list in order to get only those PCI devices which 
+// we are interested in (decided by pci_device_is_useful)
+// and return the filtered result.
+struct pci_devices * filter_pci_devices(struct pci_devices * pci) {
+  int * devices_to_get = emalloc(sizeof(int) * pci->num_devices);
+  int dev_ptr = 0;
+
+  for (int i=0; i < pci->num_devices; i++) {
+    if (pci_device_is_useful(pci->devices[i])) {
+      devices_to_get[dev_ptr] = i;
+      dev_ptr++;
+    }
+  }
+
+  struct pci_devices * pci_filtered = emalloc(sizeof(struct pci_devices));
+  pci_filtered->num_devices = dev_ptr;
+
+  if (pci_filtered->num_devices == 0) {
+    pci_filtered->devices = NULL;
+  }
+  else {
+    pci_filtered->devices = emalloc(sizeof(struct pci_device) * pci_filtered->num_devices);  
+
+    for (int i=0; i < pci_filtered->num_devices; i++)
+      pci_filtered->devices[i] = pci->devices[devices_to_get[i]];
+  }
+
+  return pci_filtered;
+}
+
+// Return a list of PCI devices that could be used to infer the SoC.
+// The criteria to determine which devices are suitable for this task
+// is decided in filter_pci_devices.
+struct pci_devices * get_pci_devices(void) {
+  struct pci_devices * pci = get_pci_paths();
+
+  if (pci == NULL)
+    return NULL;
+
+  populate_pci_devices(pci);  
+
+  return filter_pci_devices(pci);
+}