diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index 85bfec58d77c7..1bcb4b2141a6e 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -72,6 +72,7 @@ struct serial8250_config {
#define UART_CAP_UUE (1 << 12) /* UART needs IER bit 6 set (Xscale) */
#define UART_CAP_RTOIE (1 << 13) /* UART needs IER bit 4 set (Xscale, Tegra) */
#define UART_CAP_HFIFO (1 << 14) /* UART has a "hidden" FIFO */
+#define UART_CAP_RPM (1 << 15) /* Runtime PM is active while idle */
#define UART_BUG_QUOT (1 << 0) /* UART has buggy quot LSB */
#define UART_BUG_TXEN (1 << 1) /* UART has buggy TX IIR status */
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 68c44d97091b0..3cf5c98013e4e 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -38,6 +38,7 @@
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
+#include <linux/pm_runtime.h>
#ifdef CONFIG_SPARC
#include <linux/sunserialcore.h>
#endif
@@ -540,6 +541,53 @@ void serial8250_clear_and_reinit_fifos(struct uart_8250_port *p)
}
EXPORT_SYMBOL_GPL(serial8250_clear_and_reinit_fifos);
+static void serial8250_rpm_get(struct uart_8250_port *p)
+{
+ if (!(p->capabilities & UART_CAP_RPM))
+ return;
+ pm_runtime_get_sync(p->port.dev);
+}
+
+static void serial8250_rpm_put(struct uart_8250_port *p)
+{
+ if (!(p->capabilities & UART_CAP_RPM))
+ return;
+ pm_runtime_mark_last_busy(p->port.dev);
+ pm_runtime_put_autosuspend(p->port.dev);
+}
+
+/*
+ * This two wrapper ensure, that enable_runtime_pm_tx() can be called more than
+ * once and disable_runtime_pm_tx() will still disable RPM because the fifo is
+ * empty and the HW can idle again.
+ */
+static void serial8250_rpm_get_tx(struct uart_8250_port *p)
+{
+ unsigned char rpm_active;
+
+ if (!(p->capabilities & UART_CAP_RPM))
+ return;
+
+ rpm_active = xchg(&p->rpm_tx_active, 1);
+ if (rpm_active)
+ return;
+ pm_runtime_get_sync(p->port.dev);
+}
+
+static void serial8250_rpm_put_tx(struct uart_8250_port *p)
+{
+ unsigned char rpm_active;
+
+ if (!(p->capabilities & UART_CAP_RPM))
+ return;
+
+ rpm_active = xchg(&p->rpm_tx_active, 0);
+ if (!rpm_active)
+ return;
+ pm_runtime_mark_last_busy(p->port.dev);
+ pm_runtime_put_autosuspend(p->port.dev);
+}
+
/*
* IER sleep support. UARTs which have EFRs need the "extended
* capability" bit enabled. Note that on XR16C850s, we need to
@@ -554,10 +602,11 @@ static void serial8250_set_sleep(struct uart_8250_port *p, int sleep)
* offset but the UART channel may only write to the corresponding
* bit.
*/
+ serial8250_rpm_get(p);
if ((p->port.type == PORT_XR17V35X) ||
(p->port.type == PORT_XR17D15X)) {
serial_out(p, UART_EXAR_SLEEP, sleep ? 0xff : 0);
- return;
+ goto out;
}
if (p->capabilities & UART_CAP_SLEEP) {
@@ -573,6 +622,8 @@ static void serial8250_set_sleep(struct uart_8250_port *p, int sleep)
serial_out(p, UART_LCR, 0);
}
}
+out:
+ serial8250_rpm_put(p);
}
#ifdef CONFIG_SERIAL_8250_RSA
@@ -1273,6 +1324,7 @@ static inline void __stop_tx(struct uart_8250_port *p)
if (p->ier & UART_IER_THRI) {
p->ier &= ~UART_IER_THRI;
serial_out(p, UART_IER, p->ier);
+ serial8250_rpm_put_tx(p);
}
}
@@ -1280,6 +1332,7 @@ static void serial8250_stop_tx(struct uart_port *port)
{
struct uart_8250_port *up = up_to_u8250p(port);
+ serial8250_rpm_get(up);
__stop_tx(up);
/*
@@ -1289,12 +1342,14 @@ static void serial8250_stop_tx(struct uart_port *port)
up->acr |= UART_ACR_TXDIS;
serial_icr_write(up, UART_ACR, up->acr);
}
+ serial8250_rpm_put(up);
}
static void serial8250_start_tx(struct uart_port *port)
{
struct uart_8250_port *up = up_to_u8250p(port);
+ serial8250_rpm_get_tx(up);
if (up->dma && !serial8250_tx_dma(up)) {
return;
} else if (!(up->ier & UART_IER_THRI)) {
@@ -1333,9 +1388,13 @@ static void serial8250_stop_rx(struct uart_port *port)
{
struct uart_8250_port *up = up_to_u8250p(port);
+ serial8250_rpm_get(up);
+
up->ier &= ~UART_IER_RLSI;
up->port.read_status_mask &= ~UART_LSR_DR;
serial_port_out(port, UART_IER, up->ier);
+
+ serial8250_rpm_put(up);
}
static void serial8250_enable_ms(struct uart_port *port)
@@ -1347,7 +1406,10 @@ static void serial8250_enable_ms(struct uart_port *port)
return;
up->ier |= UART_IER_MSI;
+
+ serial8250_rpm_get(up);
serial_port_out(port, UART_IER, up->ier);
+ serial8250_rpm_put(up);
}
/*
@@ -1469,7 +1531,12 @@ void serial8250_tx_chars(struct uart_8250_port *up)
DEBUG_INTR("THRE...");
- if (uart_circ_empty(xmit))
+ /*
+ * With RPM enabled, we have to wait once the FIFO is empty before the
+ * HW can go idle. So we get here once again with empty FIFO and disable
+ * the interrupt and RPM in __stop_tx()
+ */
+ if (uart_circ_empty(xmit) && !(up->capabilities & UART_CAP_RPM))
__stop_tx(up);
}
EXPORT_SYMBOL_GPL(serial8250_tx_chars);
@@ -1537,9 +1604,17 @@ EXPORT_SYMBOL_GPL(serial8250_handle_irq);
static int serial8250_default_handle_irq(struct uart_port *port)
{
- unsigned int iir = serial_port_in(port, UART_IIR);
+ struct uart_8250_port *up = up_to_u8250p(port);
+ unsigned int iir;
+ int ret;
+
+ serial8250_rpm_get(up);
- return serial8250_handle_irq(port, iir);
+ iir = serial_port_in(port, UART_IIR);
+ ret = serial8250_handle_irq(port, iir);
+
+ serial8250_rpm_put(up);
+ return ret;
}
/*
@@ -1796,11 +1871,15 @@ static unsigned int serial8250_tx_empty(struct uart_port *port)
unsigned long flags;
unsigned int lsr;
+ serial8250_rpm_get(up);
+
spin_lock_irqsave(&port->lock, flags);
lsr = serial_port_in(port, UART_LSR);
up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
spin_unlock_irqrestore(&port->lock, flags);
+ serial8250_rpm_put(up);
+
return (lsr & BOTH_EMPTY) == BOTH_EMPTY ? TIOCSER_TEMT : 0;
}
@@ -1810,7 +1889,9 @@ static unsigned int serial8250_get_mctrl(struct uart_port *port)
unsigned int status;
unsigned int ret;
+ serial8250_rpm_get(up);
status = serial8250_modem_status(up);
+ serial8250_rpm_put(up);
ret = 0;
if (status & UART_MSR_DCD)
@@ -1850,6 +1931,7 @@ static void serial8250_break_ctl(struct uart_port *port, int break_state)
struct uart_8250_port *up = up_to_u8250p(port);
unsigned long flags;
+ serial8250_rpm_get(up);
spin_lock_irqsave(&port->lock, flags);
if (break_state == -1)
up->lcr |= UART_LCR_SBC;
@@ -1857,6 +1939,7 @@ static void serial8250_break_ctl(struct uart_port *port, int break_state)
up->lcr &= ~UART_LCR_SBC;
serial_port_out(port, UART_LCR, up->lcr);
spin_unlock_irqrestore(&port->lock, flags);
+ serial8250_rpm_put(up);
}
/*
@@ -1901,12 +1984,23 @@ static void wait_for_xmitr(struct uart_8250_port *up, int bits)
static int serial8250_get_poll_char(struct uart_port *port)
{
- unsigned char lsr = serial_port_in(port, UART_LSR);
+ struct uart_8250_port *up = up_to_u8250p(port);
+ unsigned char lsr;
+ int status;
+
+ serial8250_rpm_get(up);
- if (!(lsr & UART_LSR_DR))
- return NO_POLL_CHAR;
+ lsr = serial_port_in(port, UART_LSR);
- return serial_port_in(port, UART_RX);
+ if (!(lsr & UART_LSR_DR)) {
+ status = NO_POLL_CHAR;
+ goto out;
+ }
+
+ status = serial_port_in(port, UART_RX);
+out:
+ serial8250_rpm_put(up);
+ return status;
}
@@ -1916,6 +2010,7 @@ static void serial8250_put_poll_char(struct uart_port *port,
unsigned int ier;
struct uart_8250_port *up = up_to_u8250p(port);
+ serial8250_rpm_get(up);
/*
* First save the IER then disable the interrupts
*/
@@ -1937,6 +2032,7 @@ static void serial8250_put_poll_char(struct uart_port *port,
*/
wait_for_xmitr(up, BOTH_EMPTY);
serial_port_out(port, UART_IER, ier);
+ serial8250_rpm_put(up);
}
#endif /* CONFIG_CONSOLE_POLL */
@@ -1962,6 +2058,7 @@ int serial8250_do_startup(struct uart_port *port)
if (port->iotype != up->cur_iotype)
set_io_from_upio(port);
+ serial8250_rpm_get(up);
if (port->type == PORT_16C950) {
/* Wake up and initialize UART */
up->acr = 0;
@@ -1982,7 +2079,6 @@ int serial8250_do_startup(struct uart_port *port)
*/
enable_rsa(up);
#endif
-
/*
* Clear the FIFO buffers and disable them.
* (they will be reenabled in set_termios())
@@ -2006,7 +2102,8 @@ int serial8250_do_startup(struct uart_port *port)
(serial_port_in(port, UART_LSR) == 0xff)) {
printk_ratelimited(KERN_INFO "ttyS%d: LSR safety check engaged!\n",
serial_index(port));
- return -ENODEV;
+ retval = -ENODEV;
+ goto out;
}
/*
@@ -2091,7 +2188,7 @@ int serial8250_do_startup(struct uart_port *port)
} else {
retval = serial_link_irq_chain(up);
if (retval)
- return retval;
+ goto out;
}
/*
@@ -2189,8 +2286,10 @@ int serial8250_do_startup(struct uart_port *port)
outb_p(0x80, icp);
inb_p(icp);
}
-
- return 0;
+ retval = 0;
+out:
+ serial8250_rpm_put(up);
+ return retval;
}
EXPORT_SYMBOL_GPL(serial8250_do_startup);
@@ -2206,6 +2305,7 @@ void serial8250_do_shutdown(struct uart_port *port)
struct uart_8250_port *up = up_to_u8250p(port);
unsigned long flags;
+ serial8250_rpm_get(up);
/*
* Disable interrupts from this port
*/
@@ -2245,6 +2345,7 @@ void serial8250_do_shutdown(struct uart_port *port)
* the IRQ chain.
*/
serial_port_in(port, UART_RX);
+ serial8250_rpm_put(up);
del_timer_sync(&up->timer);
up->timer.function = serial8250_timeout;
@@ -2360,6 +2461,7 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
* Ok, we're now changing the port state. Do it with
* interrupts disabled.
*/
+ serial8250_rpm_get(up);
spin_lock_irqsave(&port->lock, flags);
/*
@@ -2481,6 +2583,8 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
}
serial8250_set_mctrl(port, port->mctrl);
spin_unlock_irqrestore(&port->lock, flags);
+ serial8250_rpm_put(up);
+
/* Don't rewrite B0 */
if (tty_termios_baud_rate(termios))
tty_termios_encode_baud_rate(termios, baud, baud);
@@ -3091,6 +3195,8 @@ serial8250_console_write(struct console *co, const char *s, unsigned int count)
touch_nmi_watchdog();
+ serial8250_rpm_get(up);
+
if (port->sysrq || oops_in_progress)
locked = spin_trylock_irqsave(&port->lock, flags);
else
@@ -3127,6 +3233,7 @@ serial8250_console_write(struct console *co, const char *s, unsigned int count)
if (locked)
spin_unlock_irqrestore(&port->lock, flags);
+ serial8250_rpm_put(up);
}
static int __init serial8250_console_setup(struct console *co, char *options)
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index 6fc9d7bee05ee..c267412a3ef44 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -84,6 +84,7 @@ struct uart_8250_port {
unsigned char mcr_mask; /* mask of user bits */
unsigned char mcr_force; /* mask of forced bits */
unsigned char cur_iotype; /* Running I/O type */
+ unsigned char rpm_tx_active;
/*
* Some bits in registers are cleared on a read, so they must