console : usb: USB UART console output support

Add support for console output via the USB UART.
Note that console input via the USB UART doesnt work.

Adds a simulated poll method for UART interface exposed by USB.

Jira : ZEP-775

Change-Id: I357827ea52c027eb000baed80225f422df1f3358
Signed-off-by: Jithu Joseph <jithu.joseph@intel.com>

arch/x86/soc/intel_quark/quark_se/Kconfig.defconfig.series

@@ -217,7 +217,8 @@ endif # UART_QMSI
 if UART_CONSOLE
 
 config UART_CONSOLE_ON_DEV_NAME
-	default "UART_1"
+	default "UART_1"  if USB_UART_CONSOLE = n
+	default "CDC_ACM" if USB_UART_CONSOLE
 
 endif
 

drivers/console/Kconfig

@@ -95,6 +95,20 @@ config UART_CONSOLE_DEBUG_SERVER_HOOKS
 	they are some sort of control characters, or let the regular console
 	code handle them if they are of no special significance to it.
 
+config USB_UART_CONSOLE
+	bool
+	prompt "Use USB port for console outputs"
+	depends on SERIAL
+	select CONSOLE_HAS_DRIVER
+	select USB_CDC_ACM
+	default n
+	help
+	Enable this option to use the USB UART for console output. The output
+	can be viewed from the USB host via /dev/ttyACM* port. Note that console
+	inputs from the USB UART are not functional yet. Also since the USB
+	layer currently doesnt support multiple interfaces, this shouldnt be
+	selected in conjunction with say USB Mass Storage.
+
 config RAM_CONSOLE
 	bool
 	prompt "Use RAM console"

drivers/console/uart_console.c

@@ -493,10 +493,22 @@ void uart_console_hook_install(void)
  */
 static int uart_console_init(struct device *arg)
 {
+
+	uint32_t  dtr = 0;
 	ARG_UNUSED(arg);
 
 	uart_console_dev = device_get_binding(CONFIG_UART_CONSOLE_ON_DEV_NAME);
 
+#ifdef CONFIG_USB_UART_CONSOLE
+	while (1) {
+		uart_line_ctrl_get(uart_console_dev, LINE_CTRL_DTR, &dtr);
+		if (dtr) {
+			break;
+		}
+	}
+	sys_thread_busy_wait(1000000);
+#endif
+
 	uart_console_hook_install();
 
 	return 0;
@@ -504,7 +516,9 @@ static int uart_console_init(struct device *arg)
 
 /* UART console initializes after the UART device itself */
 SYS_INIT(uart_console_init,
-#if defined(CONFIG_EARLY_CONSOLE)
+#if defined(CONFIG_USB_UART_CONSOLE)
+			APPLICATION,
+#elif defined(CONFIG_EARLY_CONSOLE)
 			PRE_KERNEL_1,
 #else
 			POST_KERNEL,

subsys/usb/class/cdc_acm.c

@@ -72,6 +72,8 @@ static struct uart_driver_api cdc_acm_driver_api;
 
 struct device *cdc_acm_dev;
 
+static struct nano_sem poll_wait_sem;
+
 /* Device data structure */
 struct cdc_acm_dev_data_t {
 	/* USB device status code */
@@ -306,6 +308,7 @@ static void cdc_acm_bulk_in(uint8_t ep, enum usb_dc_ep_cb_status_code ep_status)
 	struct cdc_acm_dev_data_t * const dev_data = DEV_DATA(cdc_acm_dev);
 
 	dev_data->tx_ready = 1;
+	nano_sem_give(&poll_wait_sem);
 	/* Call callback only if tx irq ena */
 	if (dev_data->cb && dev_data->tx_irq_ena)
 		dev_data->cb(cdc_acm_dev);
@@ -500,6 +503,7 @@ static int cdc_acm_init(struct device *dev)
 	}
 
 	dev->driver_api = &cdc_acm_driver_api;
+	nano_sem_init(&poll_wait_sem);
 
 	return 0;
 }
@@ -834,13 +838,18 @@ static int cdc_acm_poll_in(struct device *dev, unsigned char *c)
 /*
  * @brief Output a character in polled mode.
  *
- * @return 0 Since it is not supported. See the comments of
+ * The UART poll method for USB UART is simulated by waiting till
- * cdc_acm_poll_in() for details. Apps should use fifo_fill API instead.
+ * we get the next BULK In upcall from the USB device controller or 100 ms.
+ *
+ * @return the same character which is sent
  */
 static unsigned char cdc_acm_poll_out(struct device *dev,
 					     unsigned char c)
 {
-	return 0;
+	cdc_acm_fifo_fill(dev, &c, 1);
+	nano_sem_take(&poll_wait_sem, MSEC(100));
+
+	return c;
 }
 
 static struct uart_driver_api cdc_acm_driver_api = {