console_buffer: Implement console_buffer_usr

Implements user space version of buffered console. Uses the /dev/console
device.

This fixes SD card flight logs in kernel mode.

platforms/nuttx/src/px4/common/console_buffer.cpp

@@ -206,13 +206,57 @@ ssize_t console_buffer_write(struct file *filep, const char *buffer, size_t len)
 	return len;
 }
 
+ssize_t console_buffer_read(struct file *filep, char *buffer, size_t buflen)
+{
+	return g_console_buffer.read(buffer, buflen, (int *)&filep->f_pos);
+}
+
+off_t console_buffer_seek(struct file *filep, off_t offset, int whence)
+{
+	switch (whence) {
+	case SEEK_SET:
+		filep->f_pos = offset;
+		break;
+
+	case SEEK_CUR:
+		filep->f_pos += offset;
+		break;
+
+	case SEEK_END:
+		filep->f_pos = (g_console_buffer.size() + offset) % BOARD_CONSOLE_BUFFER_SIZE;
+		break;
+
+	default:
+		return -1;
+	}
+
+	return filep->f_pos;
+}
+
+int console_buffer_ioctl(struct file *filep, int cmd, unsigned long arg)
+{
+	int ret = OK;
+
+	switch (cmd) {
+	case FIONSPACE:
+		*(int *)arg = g_console_buffer.size();
+		break;
+
+	default:
+		ret = -ENOTTY;
+		break;
+	}
+
+	return ret;
+}
+
 static const struct file_operations g_console_buffer_fops = {
 	NULL,         /* open */
 	NULL,         /* close */
-	NULL,         /* read */
+	console_buffer_read, /* read */
 	console_buffer_write, /* write */
-	NULL,         /* seek */
-	NULL          /* ioctl */
+	console_buffer_seek,  /* seek */
+	console_buffer_ioctl /* ioctl */
 #ifndef CONFIG_DISABLE_POLL
 	, NULL        /* poll */
 #endif

platforms/nuttx/src/px4/common/console_buffer_usr.cpp

@@ -38,28 +38,56 @@
 #include <pthread.h>
 #include <string.h>
 #include <fcntl.h>
+#include <sys/ioctl.h>
+#include <stdio.h>
 
 #ifdef BOARD_ENABLE_CONSOLE_BUFFER
-#ifndef BOARD_CONSOLE_BUFFER_SIZE
-# define BOARD_CONSOLE_BUFFER_SIZE (1024*4) // default buffer size
-#endif
 
-
-// TODO: User side implementation of px4_console_buffer
+static int console_fd = -1;
 
 int px4_console_buffer_init()
 {
-	return 0;
+	console_fd = open(CONSOLE_BUFFER_DEVICE, O_RDWR);
+
+	if (console_fd < 0) {
+		return ERROR;
+	}
+
+	return OK;
 }
 
 int px4_console_buffer_size()
 {
-	return 0;
+	int size;
+
+	if (ioctl(console_fd, FIONSPACE, &size) < 0) {
+		return 0;
+	}
+
+	return size;
 }
 
 int px4_console_buffer_read(char *buffer, int buffer_length, int *offset)
 {
-	return 0;
+	FILE *fp;
+	ssize_t nread;
+
+	/* Open a file stream to keep track of offset */
+	fp = fdopen(dup(console_fd), "r");
+
+	if (fp == NULL) {
+		return -1;
+	}
+
+	/* The driver does not utilize file position, we have to do it for it */
+	fseek(fp, *offset, SEEK_SET);
+	nread = read(console_fd, buffer, buffer_length);
+	*offset = fseek(fp, 0, SEEK_CUR);
+
+	/* Now we can close the file */
+	fclose(fp);
+
+	return (int)nread;
 }
 
 #endif /* BOARD_ENABLE_CONSOLE_BUFFER */

platforms/nuttx/src/px4/common/px4_userspace_init.cpp

@@ -38,6 +38,7 @@
  */
 
 #include <drivers/drv_hrt.h>
+#include <px4_platform_common/console_buffer.h>
 #include <px4_platform_common/px4_work_queue/WorkQueueManager.hpp>
 #include <px4_platform_common/spi.h>
 #include <px4_platform_common/log.h>
@@ -58,6 +59,8 @@ extern "C" void px4_userspace_init(void)
 
 	px4_log_initialize();
 
+	px4_console_buffer_init();
+
 #if defined(CONFIG_SYSTEM_CDCACM) && defined(CONFIG_BUILD_PROTECTED)
 	cdcacm_init();
 #endif