tty: serial: qcom_geni_serial: Move loopback support to TIOCM_LOOP

Remove code from the driver that create and maintain loopback sysfs node.
Instead use the ioctl TIOCMSET with TIOCM_LOOP argument to set HW to
loopback mode.
Signed-off-by: Akash Asthana <akashast@codeaurora.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/1578321905-25843-3-git-send-email-akashast@codeaurora.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/qcom_geni_serial.c

@@ -89,7 +89,11 @@
 #define DEF_TX_WM		2
 #define DEF_FIFO_WIDTH_BITS	32
 #define UART_RX_WM		2
-#define MAX_LOOPBACK_CFG	3
+
+/* SE_UART_LOOPBACK_CFG */
+#define RX_TX_SORTED	BIT(0)
+#define CTS_RTS_SORTED	BIT(1)
+#define RX_TX_CTS_RTS_SORTED	(RX_TX_SORTED | CTS_RTS_SORTED)
 
 #ifdef CONFIG_CONSOLE_POLL
 #define CONSOLE_RX_BYTES_PW 1
@@ -161,30 +165,6 @@ static struct qcom_geni_serial_port qcom_geni_uart_ports[GENI_UART_PORTS] = {
 	},
 };
 
-static ssize_t loopback_show(struct device *dev,
-				struct device_attribute *attr, char *buf)
-{
-	struct qcom_geni_serial_port *port = dev_get_drvdata(dev);
-
-	return snprintf(buf, sizeof(u32), "%d\n", port->loopback);
-}
-
-static ssize_t loopback_store(struct device *dev,
-				struct device_attribute *attr, const char *buf,
-				size_t size)
-{
-	struct qcom_geni_serial_port *port = dev_get_drvdata(dev);
-	u32 loopback;
-
-	if (kstrtoint(buf, 0, &loopback) || loopback > MAX_LOOPBACK_CFG) {
-		dev_err(dev, "Invalid input\n");
-		return -EINVAL;
-	}
-	port->loopback = loopback;
-	return size;
-}
-static DEVICE_ATTR_RW(loopback);
-
 static struct qcom_geni_serial_port qcom_geni_console_port = {
 	.uport = {
 		.iotype = UPIO_MEM,
@@ -234,10 +214,14 @@ static void qcom_geni_serial_set_mctrl(struct uart_port *uport,
 							unsigned int mctrl)
 {
 	u32 uart_manual_rfr = 0;
+	struct qcom_geni_serial_port *port = to_dev_port(uport, uport);
 
 	if (uart_console(uport))
 		return;
 
+	if (mctrl & TIOCM_LOOP)
+		port->loopback = RX_TX_CTS_RTS_SORTED;
+
 	if (!(mctrl & TIOCM_RTS))
 		uart_manual_rfr = UART_MANUAL_RFR_EN | UART_RFR_NOT_READY;
 	writel(uart_manual_rfr, uport->membase + SE_UART_MANUAL_RFR);
@@ -1308,8 +1292,6 @@ static int qcom_geni_serial_probe(struct platform_device *pdev)
 	uport->private_data = drv;
 	platform_set_drvdata(pdev, port);
 	port->handle_rx = console ? handle_rx_console : handle_rx_uart;
-	if (!console)
-		device_create_file(uport->dev, &dev_attr_loopback);
 
 	ret = uart_add_one_port(drv, uport);
 	if (ret)