drivers: modem: Implement uart_pipe interface for GSM modem

Implement uart_pipe functionality for the modem so that it
integrates with the PPP implementation.

Signed-off-by: Patrik Flykt <patrik.flykt@intel.com>

drivers/modem/gsm_ppp.c

@@ -12,6 +12,8 @@ LOG_MODULE_REGISTER(gsm_ppp, CONFIG_NET_PPP_LOG_LEVEL);
 #include <sys/ring_buffer.h>
 #include <sys/util.h>
 #include <net/ppp.h>
+#include <console/uart_pipe.h>
+#include <drivers/uart.h>
 
 #include "modem_context.h"
 #include "modem_iface_uart.h"
@@ -36,8 +38,16 @@ static struct gsm_modem {
 	struct k_delayed_work gsm_configure_work;
 	char gsm_isr_buf[PPP_MRU];
 	char gsm_rx_rb_buf[PPP_MRU * 3];
+
+	bool setup_done;
+	u8_t *ppp_recv_buf;
+	size_t ppp_recv_buf_len;
+	uart_pipe_recv_cb ppp_recv_cb;
+	struct k_sem ppp_send_sem;
 } gsm;
 
+static size_t recv_buf_offset;
+
 NET_BUF_POOL_DEFINE(gsm_recv_pool, GSM_RECV_MAX_BUF, GSM_RECV_BUF_SIZE,
 		    0, NULL);
 K_THREAD_STACK_DEFINE(gsm_rx_stack, GSM_RX_STACK_SIZE);
@@ -46,13 +56,37 @@ struct k_thread gsm_rx_thread;
 
 static void gsm_rx(void)
 {
+	int bytes, r;
+
 	LOG_DBG("starting");
 
 	while (true) {
 		k_sem_take(&gsm.gsm_data.rx_sem, K_FOREVER);
-		gsm.context.cmd_handler.process(&gsm.context.cmd_handler,
+
-						&gsm.context.iface);
+		if (gsm.setup_done == false) {
-		k_yield();
+			gsm.context.cmd_handler.process(&gsm.context.cmd_handler,
+							&gsm.context.iface);
+			continue;
+		}
+
+		if (gsm.ppp_recv_cb == NULL || gsm.ppp_recv_buf == NULL ||
+		    gsm.ppp_recv_buf_len == 0) {
+			return;
+		}
+
+		r = gsm.context.iface.read(&gsm.context.iface,
+					   &gsm.ppp_recv_buf[recv_buf_offset],
+					   gsm.ppp_recv_buf_len -
+					   recv_buf_offset,
+					   &bytes);
+		if (r < 0 || bytes == 0) {
+			continue;
+		}
+
+		recv_buf_offset += bytes;
+
+		gsm.ppp_recv_buf = gsm.ppp_recv_cb(gsm.ppp_recv_buf,
+						   &recv_buf_offset);
 	}
 }
 
@@ -124,8 +158,15 @@ static void gsm_configure(struct k_work *work)
 		if (r < 0) {
 			LOG_DBG("modem setup returned %d, %s",
 				r, "retrying...");
+		} else {
+			LOG_DBG("modem setup returned %d, %s",
+				r, "enable PPP");
+			break;
 		}
 	}
+
+	gsm->setup_done = true;
+	k_sem_give(&gsm->ppp_send_sem);
 }
 
 int gsm_init(struct device *device)
@@ -134,6 +175,8 @@ int gsm_init(struct device *device)
 
 	LOG_DBG("");
 
+	k_sem_init(&gsm.ppp_send_sem, 0, 1);
+
 	gsm.cmd_handler_data.cmds[CMD_RESP] = response_cmds;
 	gsm.cmd_handler_data.cmds_len[CMD_RESP] = ARRAY_SIZE(response_cmds);
 	gsm.cmd_handler_data.read_buf = &gsm.cmd_read_buf[0];
@@ -183,5 +226,23 @@ int gsm_init(struct device *device)
 	return 0;
 }
 
+int uart_pipe_send(const u8_t *data, int len)
+{
+	k_sem_take(&gsm.ppp_send_sem, K_FOREVER);
+
+	(void)gsm.context.iface.write(&gsm.context.iface, data, len);
+
+	k_sem_give(&gsm.ppp_send_sem);
+
+	return 0;
+}
+
+void uart_pipe_register(u8_t *buf, size_t len, uart_pipe_recv_cb cb)
+{
+	gsm.ppp_recv_buf = buf;
+	gsm.ppp_recv_buf_len = len;
+	gsm.ppp_recv_cb = cb;
+}
+
 DEVICE_INIT(gsm_ppp, "modem_gsm", gsm_init, NULL, NULL, POST_KERNEL,
 	    CONFIG_MODEM_GSM_INIT_PRIORITY);

drivers/net/Kconfig

@@ -8,7 +8,7 @@ menuconfig NET_PPP
 	bool "Point-to-point (PPP) UART based driver"
 	depends on NET_L2_PPP
 	depends on NET_NATIVE
-	select UART_PIPE
+	select UART_PIPE if ! MODEM_GSM_PPP
 	select UART_INTERRUPT_DRIVEN
 
 if NET_PPP