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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
CC:     Aaron Sierra <asierra@xes-inc.com>,
        Matt Schulte <matts@commtech-fastcom.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.15 092/189] tty: serial: exar: Relocate sleep
 wake-up handling
Thread-Topic: [PATCH AUTOSEL for 4.15 092/189] tty: serial: exar: Relocate
 sleep wake-up handling
Thread-Index: AQHTz5g2jqdRZLHGn0SNCnkbjWLFGg==
Date:   Mon, 9 Apr 2018 00:17:58 +0000
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From: Aaron Sierra <asierra@xes-inc.com>

[ Upstream commit c7e1b4059075c9e8eed101d7cc5da43e95eb5e18 ]

Exar sleep wake-up handling has been done on a per-channel basis by
virtue of INT0 being accessible from each channel's address space. I
believe this was initially done out of necessity, but now that Exar
devices have their own driver, we can do things more efficiently by
registering a dedicated INT0 handler at the PCI device level.

I see this change providing the following benefits:

    1. If more than one port is active, eliminates the redundant bus
       cycles for reading INT0 on every interrupt.
    2. This note associated with hooking in the per-channel handler in
       8250_port.c is resolved:
        /* Fixme: probably not the best place for this */

Cc: Matt Schulte <matts@commtech-fastcom.com>
Signed-off-by: Aaron Sierra <asierra@xes-inc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 drivers/tty/serial/8250/8250_exar.c | 34 ++++++++++++++++++++++++++++++---=
-
 drivers/tty/serial/8250/8250_port.c | 26 --------------------------
 2 files changed, 30 insertions(+), 30 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/=
8250_exar.c
index a402878c9f30..38af306ca0e8 100644
--- a/drivers/tty/serial/8250/8250_exar.c
+++ b/drivers/tty/serial/8250/8250_exar.c
@@ -34,6 +34,7 @@
 #define PCI_DEVICE_ID_EXAR_XR17V4358		0x4358
 #define PCI_DEVICE_ID_EXAR_XR17V8358		0x8358
=20
+#define UART_EXAR_INT0		0x80
 #define UART_EXAR_8XMODE	0x88	/* 8X sampling rate select */
=20
 #define UART_EXAR_FCTR		0x08	/* Feature Control Register */
@@ -121,6 +122,7 @@ struct exar8250_board {
 struct exar8250 {
 	unsigned int		nr;
 	struct exar8250_board	*board;
+	void __iomem		*virt;
 	int			line[0];
 };
=20
@@ -131,12 +133,9 @@ static int default_setup(struct exar8250 *priv, struct=
 pci_dev *pcidev,
 	const struct exar8250_board *board =3D priv->board;
 	unsigned int bar =3D 0;
=20
-	if (!pcim_iomap_table(pcidev)[bar] && !pcim_iomap(pcidev, bar, 0))
-		return -ENOMEM;
-
 	port->port.iotype =3D UPIO_MEM;
 	port->port.mapbase =3D pci_resource_start(pcidev, bar) + offset;
-	port->port.membase =3D pcim_iomap_table(pcidev)[bar] + offset;
+	port->port.membase =3D priv->virt + offset;
 	port->port.regshift =3D board->reg_shift;
=20
 	return 0;
@@ -420,6 +419,25 @@ static void pci_xr17v35x_exit(struct pci_dev *pcidev)
 	port->port.private_data =3D NULL;
 }
=20
+/*
+ * These Exar UARTs have an extra interrupt indicator that could fire for =
a
+ * few interrupts that are not presented/cleared through IIR.  One of whic=
h is
+ * a wakeup interrupt when coming out of sleep.  These interrupts are only
+ * cleared by reading global INT0 or INT1 registers as interrupts are
+ * associated with channel 0. The INT[3:0] registers _are_ accessible from=
 each
+ * channel's address space, but for the sake of bus efficiency we register=
 a
+ * dedicated handler at the PCI device level to handle them.
+ */
+static irqreturn_t exar_misc_handler(int irq, void *data)
+{
+	struct exar8250 *priv =3D data;
+
+	/* Clear all PCI interrupts by reading INT0. No effect on IIR */
+	ioread8(priv->virt + UART_EXAR_INT0);
+
+	return IRQ_HANDLED;
+}
+
 static int
 exar_pci_probe(struct pci_dev *pcidev, const struct pci_device_id *ent)
 {
@@ -448,6 +466,9 @@ exar_pci_probe(struct pci_dev *pcidev, const struct pci=
_device_id *ent)
 		return -ENOMEM;
=20
 	priv->board =3D board;
+	priv->virt =3D pcim_iomap(pcidev, bar, 0);
+	if (!priv->virt)
+		return -ENOMEM;
=20
 	pci_set_master(pcidev);
=20
@@ -461,6 +482,11 @@ exar_pci_probe(struct pci_dev *pcidev, const struct pc=
i_device_id *ent)
 	uart.port.irq =3D pci_irq_vector(pcidev, 0);
 	uart.port.dev =3D &pcidev->dev;
=20
+	rc =3D devm_request_irq(&pcidev->dev, uart.port.irq, exar_misc_handler,
+			 IRQF_SHARED, "exar_uart", priv);
+	if (rc)
+		return rc;
+
 	for (i =3D 0; i < nr_ports && i < maxnr; i++) {
 		rc =3D board->setup(priv, pcidev, &uart, i);
 		if (rc) {
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/=
8250_port.c
index 11434551ac0a..1328c7e70108 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -441,7 +441,6 @@ static void io_serial_out(struct uart_port *p, int offs=
et, int value)
 }
=20
 static int serial8250_default_handle_irq(struct uart_port *port);
-static int exar_handle_irq(struct uart_port *port);
=20
 static void set_io_from_upio(struct uart_port *p)
 {
@@ -1883,26 +1882,6 @@ static int serial8250_default_handle_irq(struct uart=
_port *port)
 	return ret;
 }
=20
-/*
- * These Exar UARTs have an extra interrupt indicator that could
- * fire for a few unimplemented interrupts.  One of which is a
- * wakeup event when coming out of sleep.  Put this here just
- * to be on the safe side that these interrupts don't go unhandled.
- */
-static int exar_handle_irq(struct uart_port *port)
-{
-	unsigned int iir =3D serial_port_in(port, UART_IIR);
-	int ret =3D 0;
-
-	if (((port->type =3D=3D PORT_XR17V35X) || (port->type =3D=3D PORT_XR17D15=
X)) &&
-	    serial_port_in(port, UART_EXAR_INT0) !=3D 0)
-		ret =3D 1;
-
-	ret |=3D serial8250_handle_irq(port, iir);
-
-	return ret;
-}
-
 /*
  * Newer 16550 compatible parts such as the SC16C650 & Altera 16550 Soft I=
P
  * have a programmable TX threshold that triggers the THRE interrupt in
@@ -3067,11 +3046,6 @@ static void serial8250_config_port(struct uart_port =
*port, int flags)
 	if (port->type =3D=3D PORT_UNKNOWN)
 		serial8250_release_std_resource(up);
=20
-	/* Fixme: probably not the best place for this */
-	if ((port->type =3D=3D PORT_XR17V35X) ||
-	   (port->type =3D=3D PORT_XR17D15X))
-		port->handle_irq =3D exar_handle_irq;
-
 	register_dev_spec_attr_grp(up);
 	up->fcr =3D uart_config[up->port.type].fcr;
 }
--=20
2.15.1