tty: serial: qcom_geni_serial: Fix RX cancel command failure

RX cancel command fails when BT is switched on and off multiple times.

To handle this, poll for the cancel bit in SE_GENI_S_IRQ_STATUS register
instead of SE_GENI_S_CMD_CTRL_REG.

As per the HPG update, handle the RX last bit after cancel command
and flush out the RX FIFO buffer.

Signed-off-by: satya priya <skakit@codeaurora.org>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/1581415982-8793-1-git-send-email-skakit@codeaurora.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/qcom_geni_serial.c

@@ -129,6 +129,7 @@ static int handle_rx_console(struct uart_port *uport, u32 bytes, bool drop);
 static int handle_rx_uart(struct uart_port *uport, u32 bytes, bool drop);
 static unsigned int qcom_geni_serial_tx_empty(struct uart_port *port);
 static void qcom_geni_serial_stop_rx(struct uart_port *uport);
+static void qcom_geni_serial_handle_rx(struct uart_port *uport, bool drop);
 
 static const unsigned long root_freq[] = {7372800, 14745600, 19200000, 29491200,
 					32000000, 48000000, 64000000, 80000000,
@@ -599,7 +600,7 @@ static void qcom_geni_serial_stop_rx(struct uart_port *uport)
 	u32 irq_en;
 	u32 status;
 	struct qcom_geni_serial_port *port = to_dev_port(uport, uport);
-	u32 irq_clear = S_CMD_DONE_EN;
+	u32 s_irq_status;
 
 	irq_en = readl(uport->membase + SE_GENI_S_IRQ_EN);
 	irq_en &= ~(S_RX_FIFO_WATERMARK_EN | S_RX_FIFO_LAST_EN);
@@ -615,10 +616,19 @@ static void qcom_geni_serial_stop_rx(struct uart_port *uport)
 		return;
 
 	geni_se_cancel_s_cmd(&port->se);
-	qcom_geni_serial_poll_bit(uport, SE_GENI_S_CMD_CTRL_REG,
-					S_GENI_CMD_CANCEL, false);
+	qcom_geni_serial_poll_bit(uport, SE_GENI_S_IRQ_STATUS,
+					S_CMD_CANCEL_EN, true);
+	/*
+	 * If timeout occurs secondary engine remains active
+	 * and Abort sequence is executed.
+	 */
+	s_irq_status = readl(uport->membase + SE_GENI_S_IRQ_STATUS);
+	/* Flush the Rx buffer */
+	if (s_irq_status & S_RX_FIFO_LAST_EN)
+		qcom_geni_serial_handle_rx(uport, true);
+	writel(s_irq_status, uport->membase + SE_GENI_S_IRQ_CLEAR);
+
 	status = readl(uport->membase + SE_GENI_STATUS);
-	writel(irq_clear, uport->membase + SE_GENI_S_IRQ_CLEAR);
 	if (status & S_GENI_CMD_ACTIVE)
 		qcom_geni_serial_abort_rx(uport);
 }