xuartps: Implement BREAK detection for ZynqMP

This patch adds the uart BREAK detection support for Zynq Ultrascale+ MPSoC
platform

Signed-off-by: Nava kishore Manne <navam@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 2d3a3d5d262c6d77b9c97b230ab9ad8e1ce0055d..f214c7f4f2cb85212b54c9b3f48d39b8125b7c2c 100644 (file)
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -127,10 +127,12 @@ MODULE_PARM_DESC(rx_timeout, "Rx timeout, 1-255");
 #define CDNS_UART_IXR_RXTRIG   0x00000001 /* RX FIFO trigger interrupt */
 #define CDNS_UART_IXR_RXFULL   0x00000004 /* RX FIFO full interrupt. */
 #define CDNS_UART_IXR_RXEMPTY  0x00000002 /* RX FIFO empty interrupt. */
-#define CDNS_UART_IXR_MASK     0x00001FFF /* Valid bit mask */
+#define CDNS_UART_IXR_MASK     0x00003FFF /* Valid bit mask */
 
 /* Goes in read_status_mask for break detection as the HW doesn't do it*/
-#define CDNS_UART_IXR_BRK      0x80000000
+#define CDNS_UART_IXR_BRK      0x00002000
+
+#define CDNS_UART_BRK_DET      BIT(1)
 
 /*
  * Modem Control register:
@@ -171,7 +173,12 @@ struct cdns_uart {
        struct clk              *pclk;
        unsigned int            baud;
        struct notifier_block   clk_rate_change_nb;
+       u32                     quirks;
+};
+struct cdns_platform_data {
+       u32 quirks;
 };
+
 #define to_cdns_uart(_nb) container_of(_nb, struct cdns_uart, \
                clk_rate_change_nb);
 
@@ -228,27 +235,38 @@ static void cdns_uart_handle_tx(void *dev_id)
 static void cdns_uart_handle_rx(void *dev_id, unsigned int isrstatus)
 {
        struct uart_port *port = (struct uart_port *)dev_id;
+       struct cdns_uart *cdns_uart = port->private_data;
        unsigned int data;
        unsigned int framerrprocessed = 0;
        char status = TTY_NORMAL;
+       bool is_brk_support;
+
+       is_brk_support = cdns_uart->quirks & CDNS_UART_BRK_DET;
 
        while ((cdns_uart_readl(CDNS_UART_SR_OFFSET) &
                CDNS_UART_SR_RXEMPTY) != CDNS_UART_SR_RXEMPTY) {
                data = cdns_uart_readl(CDNS_UART_FIFO_OFFSET);
                port->icount.rx++;
                /*
-                * There is no hardware break detection, so we interpret
+                * There is no hardware break detection in Zynq, so we interpret
                 * framing error with all-zeros data as a break sequence.
                 * Most of the time, there's another non-zero byte at the
                 * end of the sequence.
                 */
-               if (isrstatus & CDNS_UART_IXR_FRAMING) {
+               if (!is_brk_support && (isrstatus & CDNS_UART_IXR_FRAMING)) {
                        if (!data) {
                                port->read_status_mask |= CDNS_UART_IXR_BRK;
                                framerrprocessed = 1;
                                continue;
                        }
                }
+               if (is_brk_support && (isrstatus & CDNS_UART_IXR_BRK)) {
+                       port->icount.brk++;
+                       status = TTY_BREAK;
+                       if (uart_handle_break(port))
+                               continue;
+               }
+
                isrstatus &= port->read_status_mask;
                isrstatus &= ~port->ignore_status_mask;
 
@@ -769,8 +787,11 @@ static void cdns_uart_set_termios(struct uart_port *port,
  */
 static int cdns_uart_startup(struct uart_port *port)
 {
+       struct cdns_uart *cdns_uart = port->private_data;
+       bool is_brk_support;
        unsigned int retval = 0, status = 0;
 
+       is_brk_support = cdns_uart->quirks & CDNS_UART_BRK_DET;
        retval = request_irq(port->irq, cdns_uart_isr, 0, CDNS_UART_NAME,
                                                                (void *)port);
        if (retval)
@@ -833,6 +854,11 @@ static int cdns_uart_startup(struct uart_port *port)
                CDNS_UART_IXR_FRAMING | CDNS_UART_IXR_OVERRUN |
                CDNS_UART_IXR_RXTRIG | CDNS_UART_IXR_TOUT,
                CDNS_UART_IER_OFFSET);
+       if (is_brk_support) {
+               status = cdns_uart_readl(CDNS_UART_IMR_OFFSET);
+               cdns_uart_writel((status | CDNS_UART_IXR_BRK),
+                                       CDNS_UART_IER_OFFSET);
+       }
 
        return retval;
 }
@@ -1340,6 +1366,16 @@ static int cdns_uart_resume(struct device *device)
 
 static SIMPLE_DEV_PM_OPS(cdns_uart_dev_pm_ops, cdns_uart_suspend,
                cdns_uart_resume);
+static const struct cdns_platform_data zynqmp_uart_def = {
+                                       .quirks = CDNS_UART_BRK_DET, };
+/* Match table for of_platform binding */
+static const struct of_device_id cdns_uart_of_match[] = {
+       { .compatible = "xlnx,xuartps", },
+       { .compatible = "cdns,uart-r1p8", },
+       { .compatible = "cdns,uart-r1p12", .data = &zynqmp_uart_def },
+       {}
+};
+MODULE_DEVICE_TABLE(of, cdns_uart_of_match);
 
 /**
  * cdns_uart_probe - Platform driver probe
@@ -1353,12 +1389,20 @@ static int cdns_uart_probe(struct platform_device *pdev)
        struct uart_port *port;
        struct resource *res;
        struct cdns_uart *cdns_uart_data;
+       const struct of_device_id *match;
 
        cdns_uart_data = devm_kzalloc(&pdev->dev, sizeof(*cdns_uart_data),
                        GFP_KERNEL);
        if (!cdns_uart_data)
                return -ENOMEM;
 
+       match = of_match_node(cdns_uart_of_match, pdev->dev.of_node);
+       if (match && match->data) {
+               const struct cdns_platform_data *data = match->data;
+
+               cdns_uart_data->quirks = data->quirks;
+       }
+
        cdns_uart_data->pclk = devm_clk_get(&pdev->dev, "pclk");
        if (IS_ERR(cdns_uart_data->pclk)) {
                cdns_uart_data->pclk = devm_clk_get(&pdev->dev, "aper_clk");
@@ -1481,14 +1525,6 @@ static int cdns_uart_remove(struct platform_device *pdev)
        return rc;
 }
 
-/* Match table for of_platform binding */
-static struct of_device_id cdns_uart_of_match[] = {
-       { .compatible = "xlnx,xuartps", },
-       { .compatible = "cdns,uart-r1p8", },
-       {}
-};
-MODULE_DEVICE_TABLE(of, cdns_uart_of_match);
-
 static struct platform_driver cdns_uart_platform_driver = {
        .probe   = cdns_uart_probe,
        .remove  = cdns_uart_remove,