[linux-yocto] [PATCH 02/15] serial: 8250_port: factor out serial8250_do_restore_context()

[Nilesh Bacchewar]

From: Andy Shevchenko <andriy.shevchenko at linux.intel.com>

Backport:
 - Upstream-Status: Pending.
 [https://bitbucket.org/andy-shev/linux/commits/fe798435558f5214855a60ac15df4fe6d48e956c?at=master]

The new function serial8250_do_restore_context() is used to write the saved
register values to the hardware. It is used in serial8250_do_set_termios() and
will be used by the individual drivers to restore context when resuming.

Signed-off-by: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
---
 drivers/tty/serial/8250/8250_port.c | 65 ++++++++++++++++++++++++-------------
 include/linux/serial_8250.h         |  5 +++
 2 files changed, 47 insertions(+), 23 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 342e2f1..d8d52db 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -2246,6 +2246,42 @@ serial8250_get_baud_rate(struct uart_port *port, struct ktermios *termios,
 				  (port->uartclk + tolerance) / 16);
 }
 
+void serial8250_do_restore_context(struct uart_port *port)
+{
+	struct uart_8250_port *up = up_to_u8250p(port);
+
+	/* Write extended features at first */
+	if (up->capabilities & UART_CAP_EFR) {
+		serial_port_out(port, UART_LCR, UART_LCR_CONF_MODE_B);
+		if (port->flags & UPF_EXAR_EFR)
+			serial_port_out(port, UART_XR_EFR, up->efr);
+		else
+			serial_port_out(port, UART_EFR, up->efr);
+	}
+
+	serial8250_set_divisor(port, up->baud, up->quot, up->frac);
+
+	/*
+	 * LCR DLAB must be set to enable 64-byte FIFO mode. If the FCR
+	 * is written without DLAB set, this mode will be disabled.
+	 */
+	if (port->type == PORT_16750)
+		serial_port_out(port, UART_FCR, up->fcr);
+
+	serial_port_out(port, UART_LCR, up->lcr);	/* reset DLAB */
+	if (port->type != PORT_16750) {
+		/* emulated UARTs (Lucent Venus 167x) need two steps */
+		if (up->fcr & UART_FCR_ENABLE_FIFO)
+			serial_port_out(port, UART_FCR, UART_FCR_ENABLE_FIFO);
+		serial_port_out(port, UART_FCR, up->fcr);	/* set fcr */
+	}
+	serial8250_set_mctrl(port, port->mctrl);
+
+	/* Enable interrupts at last */
+	serial_port_out(port, UART_IER, up->ier);
+}
+EXPORT_SYMBOL_GPL(serial8250_do_restore_context);
+
 void
 serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
 		          struct ktermios *old)
@@ -2268,6 +2304,9 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
 	spin_lock_irqsave(&port->lock, flags);
 
 	up->lcr = cval;					/* Save computed LCR */
+	up->baud = baud;				/* Save baud rate */
+	up->quot = quot;				/* Save quot */
+	up->frac = frac;				/* Save fraction */
 
 	if (up->capabilities & UART_CAP_FIFO && port->fifosize > 1) {
 		/* NOTE: If fifo_bug is not set, a user can set RX_trigger. */
@@ -2336,8 +2375,6 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
 	if (up->capabilities & UART_CAP_RTOIE)
 		up->ier |= UART_IER_RTOIE;
 
-	serial_port_out(port, UART_IER, up->ier);
-
 	if (up->capabilities & UART_CAP_EFR) {
 		unsigned char efr = 0;
 		/*
@@ -2348,30 +2385,12 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
 		if (termios->c_cflag & CRTSCTS)
 			efr |= UART_EFR_CTS;
 
-		serial_port_out(port, UART_LCR, UART_LCR_CONF_MODE_B);
-		if (port->flags & UPF_EXAR_EFR)
-			serial_port_out(port, UART_XR_EFR, efr);
-		else
-			serial_port_out(port, UART_EFR, efr);
+		up->efr = efr;
 	}
 
-	serial8250_set_divisor(port, baud, quot, frac);
+	/* Write saved values to the registers */
+	serial8250_do_restore_context(port);
 
-	/*
-	 * LCR DLAB must be set to enable 64-byte FIFO mode. If the FCR
-	 * is written without DLAB set, this mode will be disabled.
-	 */
-	if (port->type == PORT_16750)
-		serial_port_out(port, UART_FCR, up->fcr);
-
-	serial_port_out(port, UART_LCR, up->lcr);	/* reset DLAB */
-	if (port->type != PORT_16750) {
-		/* emulated UARTs (Lucent Venus 167x) need two steps */
-		if (up->fcr & UART_FCR_ENABLE_FIFO)
-			serial_port_out(port, UART_FCR, UART_FCR_ENABLE_FIFO);
-		serial_port_out(port, UART_FCR, up->fcr);	/* set fcr */
-	}
-	serial8250_set_mctrl(port, port->mctrl);
 	spin_unlock_irqrestore(&port->lock, flags);
 	serial8250_rpm_put(up);
 
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index faa0e03..d23b2d4 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -92,6 +92,7 @@ struct uart_8250_port {
 	bool			fifo_bug;	/* min RX trigger if enabled */
 	unsigned int		tx_loadsz;	/* transmit fifo load size */
 	unsigned char		acr;
+	unsigned char		efr;
 	unsigned char		fcr;
 	unsigned char		ier;
 	unsigned char		lcr;
@@ -100,6 +101,9 @@ struct uart_8250_port {
 	unsigned char		mcr_force;	/* mask of forced bits */
 	unsigned char		cur_iotype;	/* Running I/O type */
 	unsigned int		rpm_tx_active;
+	unsigned int		baud;
+	unsigned int		quot;
+	unsigned int		frac;
 	unsigned char		canary;		/* non-zero during system sleep
 						 *   if no_console_suspend
 						 */
@@ -138,6 +142,7 @@ extern int early_serial_setup(struct uart_port *port);
 
 extern int early_serial8250_setup(struct earlycon_device *device,
 					 const char *options);
+void serial8250_do_restore_context(struct uart_port *port);
 extern void serial8250_do_set_termios(struct uart_port *port,
 		struct ktermios *termios, struct ktermios *old);
 extern int serial8250_do_startup(struct uart_port *port);
-- 
1.9.1