[PATCH AUTOSEL for 4.14 076/161] tty: serial: exar: Relocate sleep wake-up handling

Sasha Levin
2018-04-09T00:24:00Z

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 c55624703fdf..e0aa5f03004c 100644
--- a/drivers/tty/serial/8250/8250_exar.c
+++ b/drivers/tty/serial/8250/8250_exar.c
@@ -37,6 +37,7 @@
#define PCI_DEVICE_ID_EXAR_XR17V4358 0x4358
#define PCI_DEVICE_ID_EXAR_XR17V8358 0x8358

+#define UART_EXAR_INT0 0x80
#define UART_EXAR_8XMODE 0x88 /* 8X sampling rate select */

#define UART_EXAR_FCTR 0x08 /* Feature Control Register */
@@ -124,6 +125,7 @@ struct exar8250_board {
struct exar8250 {
unsigned int nr;
struct exar8250_board *board;
+ void __iomem *virt;
int line[0];
};

@@ -134,12 +136,9 @@ static int default_setup(struct exar8250 *priv, struct pci_dev *pcidev,
const struct exar8250_board *board = priv->board;
unsigned int bar = 0;

- if (!pcim_iomap_table(pcidev)[bar] && !pcim_iomap(pcidev, bar, 0))
- return -ENOMEM;
-
port->port.iotype = UPIO_MEM;
port->port.mapbase = pci_resource_start(pcidev, bar) + offset;
- port->port.membase = pcim_iomap_table(pcidev)[bar] + offset;
+ port->port.membase = priv->virt + offset;
port->port.regshift = board->reg_shift;

return 0;
@@ -423,6 +422,25 @@ static void pci_xr17v35x_exit(struct pci_dev *pcidev)
port->port.private_data = NULL;
}

+/*
+ * These Exar UARTs have an extra interrupt indicator that could fire for a
+ * few interrupts that are not presented/cleared through IIR. One of which 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 = 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)
{
@@ -451,6 +469,9 @@ exar_pci_probe(struct pci_dev *pcidev, const struct pci_device_id *ent)
return -ENOMEM;

priv->board = board;
+ priv->virt = pcim_iomap(pcidev, bar, 0);
+ if (!priv->virt)
+ return -ENOMEM;

pci_set_master(pcidev);

@@ -464,6 +485,11 @@ exar_pci_probe(struct pci_dev *pcidev, const struct pci_device_id *ent)
uart.port.irq = pci_irq_vector(pcidev, 0);
uart.port.dev = &pcidev->dev;

+ rc = devm_request_irq(&pcidev->dev, uart.port.irq, exar_misc_handler,
+ IRQF_SHARED, "exar_uart", priv);
+ if (rc)
+ return rc;
+
for (i = 0; i < nr_ports && i < maxnr; i++) {
rc = 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 8dcfd4978a03..e9d4420869dd 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -445,7 +445,6 @@ static void io_serial_out(struct uart_port *p, int offset, int value)
}

static int serial8250_default_handle_irq(struct uart_port *port);
-static int exar_handle_irq(struct uart_port *port);

static void set_io_from_upio(struct uart_port *p)
{
@@ -1890,26 +1889,6 @@ static int serial8250_default_handle_irq(struct uart_port *port)
return ret;
}

-/*
- * 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 = serial_port_in(port, UART_IIR);
- int ret = 0;
-
- if (((port->type == PORT_XR17V35X) || (port->type == PORT_XR17D15X)) &&
- serial_port_in(port, UART_EXAR_INT0) != 0)
- ret = 1;
-
- ret |= serial8250_handle_irq(port, iir);
-
- return ret;
-}
-
/*
* Newer 16550 compatible parts such as the SC16C650 & Altera 16550 Soft IP
* have a programmable TX threshold that triggers the THRE interrupt in
@@ -3074,11 +3053,6 @@ static void serial8250_config_port(struct uart_port *port, int flags)
if (port->type == PORT_UNKNOWN)
serial8250_release_std_resource(up);

- /* Fixme: probably not the best place for this */
- if ((port->type == PORT_XR17V35X) ||
- (port->type == PORT_XR17D15X))
- port->handle_irq = exar_handle_irq;
-
register_dev_spec_attr_grp(up);
up->fcr = uart_config[up->port.type].fcr;
}
--
2.15.1