[PATCH] xen/char: implement suspend/resume calls for SCIF driver

[Mykola Kvach <xakep.amatop@xxxxxxxxx>]

From: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>

The changes have been tested only on the Renesas R-Car H3 Starter Kit board.

Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
Signed-off-by: Mykola Kvach <mykola_kvach@xxxxxxxx>
---
 xen/drivers/char/scif-uart.c | 34 ++++++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/xen/drivers/char/scif-uart.c b/xen/drivers/char/scif-uart.c
index 757793ca45..ce0f87c650 100644
--- a/xen/drivers/char/scif-uart.c
+++ b/xen/drivers/char/scif-uart.c
@@ -139,9 +139,8 @@ static void scif_uart_interrupt(int irq, void *data)
     }
 }
 
-static void __init scif_uart_init_preirq(struct serial_port *port)
+static void scif_uart_disable(struct scif_uart *uart)
 {
-    struct scif_uart *uart = port->uart;
     const struct port_params *params = uart->params;
 
     /*
@@ -155,6 +154,14 @@ static void __init scif_uart_init_preirq(struct 
serial_port *port)
 
     /* Reset TX/RX FIFOs */
     scif_writew(uart, SCIF_SCFCR, SCFCR_RFRST | SCFCR_TFRST);
+}
+
+static void scif_uart_init_preirq(struct serial_port *port)
+{
+    struct scif_uart *uart = port->uart;
+    const struct port_params *params = uart->params;
+
+    scif_uart_disable(uart);
 
     /* Clear all errors and flags */
     scif_readw(uart, params->status_reg);
@@ -271,6 +278,27 @@ static void scif_uart_stop_tx(struct serial_port *port)
     scif_writew(uart, SCIF_SCSCR, scif_readw(uart, SCIF_SCSCR) & ~SCSCR_TIE);
 }
 
+static void scif_uart_suspend(struct serial_port *port)
+{
+    struct scif_uart *uart = port->uart;
+
+    scif_uart_stop_tx(port);
+    scif_uart_disable(uart);
+}
+
+static void scif_uart_resume(struct serial_port *port)
+{
+    struct scif_uart *uart = port->uart;
+    const struct port_params *params = uart->params;
+    uint16_t ctrl;
+
+    scif_uart_init_preirq(port);
+
+    /* Enable TX/RX and Error Interrupts  */
+    ctrl = scif_readw(uart, SCIF_SCSCR);
+    scif_writew(uart, SCIF_SCSCR, ctrl | params->irq_flags);
+}
+
 static struct uart_driver __read_mostly scif_uart_driver = {
     .init_preirq  = scif_uart_init_preirq,
     .init_postirq = scif_uart_init_postirq,
@@ -281,6 +309,8 @@ static struct uart_driver __read_mostly scif_uart_driver = {
     .start_tx     = scif_uart_start_tx,
     .stop_tx      = scif_uart_stop_tx,
     .vuart_info   = scif_vuart_info,
+    .suspend      = scif_uart_suspend,
+    .resume       = scif_uart_resume,
 };
 
 static const struct dt_device_match scif_uart_dt_match[] __initconst =
-- 
2.43.0