tty: serial core: decouple pm states from ACPI

The serial core is using power states lifted from ACPI for no
good reason. Remove this reference from the documentation and
alter all users to use an enum specific to the serial core
instead, and define it in <linux/serial_core.h>.

Signed-off-by: Linus Walleij <[e-mail]>
Acked-by: Alan Cox <[e-mail]>
Reviewed-by: Daniel Lezcano <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

Documentation/serial/driver

···
 
   pm(port,state,oldstate)
 	Perform any power management related activities on the specified
-	port.  State indicates the new state (defined by ACPI D0-D3),
-	oldstate indicates the previous state.  Essentially, D0 means
-	fully on, D3 means powered down.
+	port.  State indicates the new state (defined by
+	enum uart_pm_state), oldstate indicates the previous state.
 
 	This function should not be used to grab any resources.
 

drivers/tty/serial/serial_core.c

···
 static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
 					struct ktermios *old_termios);
 static void uart_wait_until_sent(struct tty_struct *tty, int timeout);
-static void uart_change_pm(struct uart_state *state, int pm_state);
+static void uart_change_pm(struct uart_state *state,
+			   enum uart_pm_state pm_state);
 
 static void uart_port_shutdown(struct tty_port *port);
 
···
 		spin_lock_irqsave(&port->lock, flags);
 	} else if (!uart_console(uport)) {
 		spin_unlock_irqrestore(&port->lock, flags);
-		uart_change_pm(state, 3);
+		uart_change_pm(state, UART_PM_STATE_OFF);
 		spin_lock_irqsave(&port->lock, flags);
 	}
 
···
 	 * Make sure the device is in D0 state.
 	 */
 	if (port->count == 1)
-		uart_change_pm(state, 0);
+		uart_change_pm(state, UART_PM_STATE_ON);
 
 	/*
 	 * Start up the serial port.
···
 {
 	struct uart_state *state = drv->state + i;
 	struct tty_port *port = &state->port;
-	int pm_state;
+	enum uart_pm_state pm_state;
 	struct uart_port *uport = state->uart_port;
 	char stat_buf[32];
 	unsigned int status;
···
 	if (capable(CAP_SYS_ADMIN)) {
 		mutex_lock(&port->mutex);
 		pm_state = state->pm_state;
-		if (pm_state)
-			uart_change_pm(state, 0);
+		if (pm_state != UART_PM_STATE_ON)
+			uart_change_pm(state, UART_PM_STATE_ON);
 		spin_lock_irq(&uport->lock);
 		status = uport->ops->get_mctrl(uport);
 		spin_unlock_irq(&uport->lock);
-		if (pm_state)
+		if (pm_state != UART_PM_STATE_ON)
 			uart_change_pm(state, pm_state);
 		mutex_unlock(&port->mutex);
 
···
  *
  * Locking: port->mutex has to be held
  */
-static void uart_change_pm(struct uart_state *state, int pm_state)
+static void uart_change_pm(struct uart_state *state,
+			   enum uart_pm_state pm_state)
 {
 	struct uart_port *port = state->uart_port;
 
···
 		console_stop(uport->cons);
 
 	if (console_suspend_enabled || !uart_console(uport))
-		uart_change_pm(state, 3);
+		uart_change_pm(state, UART_PM_STATE_OFF);
 
 	mutex_unlock(&port->mutex);
 
···
 			termios = port->tty->termios;
 
 		if (console_suspend_enabled)
-			uart_change_pm(state, 0);
+			uart_change_pm(state, UART_PM_STATE_ON);
 		uport->ops->set_termios(uport, &termios, NULL);
 		if (console_suspend_enabled)
 			console_start(uport->cons);
···
 		const struct uart_ops *ops = uport->ops;
 		int ret;
 
-		uart_change_pm(state, 0);
+		uart_change_pm(state, UART_PM_STATE_ON);
 		spin_lock_irq(&uport->lock);
 		ops->set_mctrl(uport, 0);
 		spin_unlock_irq(&uport->lock);
···
 		uart_report_port(drv, port);
 
 		/* Power up port for set_mctrl() */
-		uart_change_pm(state, 0);
+		uart_change_pm(state, UART_PM_STATE_ON);
 
 		/*
 		 * Ensure that the modem control lines are de-activated.
···
 		 * console if we have one.
 		 */
 		if (!uart_console(port))
-			uart_change_pm(state, 3);
+			uart_change_pm(state, UART_PM_STATE_OFF);
 	}
 }
 
···
 	}
 
 	state->uart_port = uport;
-	state->pm_state = -1;
+	state->pm_state = UART_PM_STATE_UNDEFINED;
 
 	uport->cons = drv->cons;
 	uport->state = state;

include/linux/serial_core.h

···
 	up->serial_out(up, offset, value);
 }
 
+/**
+ * enum uart_pm_state - power states for UARTs
+ * @UART_PM_STATE_ON: UART is powered, up and operational
+ * @UART_PM_STATE_OFF: UART is powered off
+ * @UART_PM_STATE_UNDEFINED: sentinel
+ */
+enum uart_pm_state {
+	UART_PM_STATE_ON = 0,
+	UART_PM_STATE_OFF = 3, /* number taken from ACPI */
+	UART_PM_STATE_UNDEFINED,
+};
+
 /*
  * This is the state information which is persistent across opens.
  */
 struct uart_state {
 	struct tty_port		port;
 
-	int			pm_state;
+	enum uart_pm_state	pm_state;
 	struct circ_buf		xmit;
 
 	struct uart_port	*uart_port;