[PATCH v6 tty-next 4/4] serial: 8250_pci1xxxx: Add power management functions to quad-uart driver

[Kumaravel Thiagarajan]

pci1xxxx's quad-uart function has the capability to wake up UART
from suspend state. Enable wakeup before entering into suspend and
disable wakeup on resume.

Co-developed-by: Tharun Kumar P <tharunkumar.pasumarthi@xxxxxxxxxxxxx>
Signed-off-by: Tharun Kumar P <tharunkumar.pasumarthi@xxxxxxxxxxxxx>
Signed-off-by: Kumaravel Thiagarajan <kumaravel.thiagarajan@xxxxxxxxxxxxx>
---
Changes in v6:
- No Change

Changes in v5:
- Corrected commit message

Changes in v4:
- No Change

Changes in v3:
- Handled race condition in suspend and resume callbacks

Changes in v2:
- Use DEFINE_SIMPLE_DEV_PM_OPS instead of SIMPLE_DEV_PM_OPS.
- Use pm_sleep_ptr instead of CONFIG_PM_SLEEP.
- Change the return data type of pci1xxxx_port_suspend to bool from int.
---
 drivers/tty/serial/8250/8250_pci1xxxx.c | 116 ++++++++++++++++++++++++
 1 file changed, 116 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_pci1xxxx.c b/drivers/tty/serial/8250/8250_pci1xxxx.c
index 7585066d6baf..594f0152daf2 100644
--- a/drivers/tty/serial/8250/8250_pci1xxxx.c
+++ b/drivers/tty/serial/8250/8250_pci1xxxx.c
@@ -192,6 +192,116 @@ static const struct serial_rs485 pci1xxxx_rs485_supported = {
 	/* Delay RTS before send is not supported */
 };
 
+static bool pci1xxxx_port_suspend(int line)
+{
+	struct uart_8250_port *up = serial8250_get_port(line);
+	struct uart_port *port = &up->port;
+	struct tty_port *tport = &port->state->port;
+	unsigned long flags;
+	bool ret = false;
+	u8 wakeup_mask;
+
+	mutex_lock(&tport->mutex);
+	if (port->suspended == 0 && port->dev) {
+		wakeup_mask = readb(up->port.membase + UART_WAKE_MASK_REG);
+
+		spin_lock_irqsave(&port->lock, flags);
+		port->mctrl &= ~TIOCM_OUT2;
+		port->ops->set_mctrl(port, port->mctrl);
+		spin_unlock_irqrestore(&port->lock, flags);
+
+		ret = (wakeup_mask & UART_WAKE_SRCS) != UART_WAKE_SRCS;
+	}
+
+	writeb(UART_WAKE_SRCS, port->membase + UART_WAKE_REG);
+	mutex_unlock(&tport->mutex);
+
+	return ret;
+}
+
+static void pci1xxxx_port_resume(int line)
+{
+	struct uart_8250_port *up = serial8250_get_port(line);
+	struct uart_port *port = &up->port;
+	struct tty_port *tport = &port->state->port;
+	unsigned long flags;
+
+	mutex_lock(&tport->mutex);
+	writeb(UART_BLOCK_SET_ACTIVE, port->membase + UART_ACTV_REG);
+	writeb(UART_WAKE_SRCS, port->membase + UART_WAKE_REG);
+
+	if (port->suspended == 0) {
+		spin_lock_irqsave(&port->lock, flags);
+		port->mctrl |= TIOCM_OUT2;
+		port->ops->set_mctrl(port, port->mctrl);
+		spin_unlock_irqrestore(&port->lock, flags);
+	}
+	mutex_unlock(&tport->mutex);
+}
+
+static int pci1xxxx_suspend(struct device *dev)
+{
+	struct pci1xxxx_8250 *priv = dev_get_drvdata(dev);
+	struct pci_dev *pcidev = to_pci_dev(dev);
+	bool wakeup = false;
+	unsigned int data;
+	void __iomem *p;
+	int i;
+
+	for (i = 0; i < priv->nr; i++) {
+		if (priv->line[i] >= 0) {
+			serial8250_suspend_port(priv->line[i]);
+			wakeup |= pci1xxxx_port_suspend(priv->line[i]);
+		}
+	}
+
+	p = pci_ioremap_bar(pcidev, 0);
+	if (!p) {
+		dev_err(dev, "remapping of bar 0 memory failed");
+		return -ENOMEM;
+	}
+
+	data = readl(p + UART_RESET_REG);
+	writel(data | UART_RESET_D3_RESET_DISABLE, p + UART_RESET_REG);
+
+	if (wakeup)
+		writeb(UART_PCI_CTRL_D3_CLK_ENABLE, p + UART_PCI_CTRL_REG);
+
+	iounmap(p);
+	device_set_wakeup_enable(dev, true);
+	pci_wake_from_d3(pcidev, true);
+
+	return 0;
+}
+
+static int pci1xxxx_resume(struct device *dev)
+{
+	struct pci1xxxx_8250 *priv = dev_get_drvdata(dev);
+	struct pci_dev *pcidev = to_pci_dev(dev);
+	unsigned int data;
+	void __iomem *p;
+	int i;
+
+	p = pci_ioremap_bar(pcidev, 0);
+	if (!p) {
+		dev_err(dev, "remapping of bar 0 memory failed");
+		return -ENOMEM;
+	}
+
+	data = readl(p + UART_RESET_REG);
+	writel(data & ~UART_RESET_D3_RESET_DISABLE, p + UART_RESET_REG);
+	iounmap(p);
+
+	for (i = 0; i < priv->nr; i++) {
+		if (priv->line[i] >= 0) {
+			pci1xxxx_port_resume(priv->line[i]);
+			serial8250_resume_port(priv->line[i]);
+		}
+	}
+
+	return 0;
+}
+
 static int pci1xxxx_setup(struct pci1xxxx_8250 *priv,
 			  struct uart_8250_port *port, int port_idx)
 {
@@ -323,6 +433,9 @@ static void pci1xxxx_serial_remove(struct pci_dev *dev)
 	}
 }
 
+static DEFINE_SIMPLE_DEV_PM_OPS(pci1xxxx_pm_ops, pci1xxxx_suspend,
+				pci1xxxx_resume);
+
 static const struct pci_device_id pci1xxxx_pci_tbl[] = {
 	{ PCI_DEVICE(PCI_VENDOR_ID_EFAR, PCI_DEVICE_ID_EFAR_PCI11010) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_EFAR, PCI_DEVICE_ID_EFAR_PCI11101) },
@@ -337,6 +450,9 @@ static struct pci_driver pci1xxxx_pci_driver = {
 	.name = "pci1xxxx serial",
 	.probe = pci1xxxx_serial_probe,
 	.remove = pci1xxxx_serial_remove,
+	.driver = {
+		.pm     = pm_sleep_ptr(&pci1xxxx_pm_ops),
+	},
 	.id_table = pci1xxxx_pci_tbl,
 };
 module_pci_driver(pci1xxxx_pci_driver);
-- 
2.25.1