tty: serial: men_z135_uart: Fix driver for changes in hardware

16z135 IP Core has changed so the driver needs to be updated to respect
these changes. The following changes have been made:

* Don't invert the 16z135 modem status register when reading.
* Add module parameter to configure the (baud rate dependent) RX timeout.
  Character timeout in seconds = (timeout_reg * baud_reg * 4)/freq_reg.
* Enable the handling of UART core's automatic flow control feature.
  When AFE is active disable generation of modem status IRQs.
* Rework the handling of IRQs to be conform with newer FPGA versions and
  take precautions not to miss an interrupt because of the destructive read
  of the IIR register.
* Correct men_z135_handle_modem_status(), MSR is stat_reg[15:8] not
  stat_reg[7:0]
* Correct calling of uart_handle_{dcd,cts}_change()
* Reset CLOCAL when CRTSCTS is set

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@men.de>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/men_z135_uart.c b/drivers/tty/serial/men_z135_uart.c
index 517cd073dc0856a7a5e078d1b3ecc95d698189b5..35c55505b3eb32e38536c2abbce86cfe523b6288 100644 (file)
--- a/drivers/tty/serial/men_z135_uart.c
+++ b/drivers/tty/serial/men_z135_uart.c
@@ -23,7 +23,6 @@
 #define MEN_Z135_MAX_PORTS             12
 #define MEN_Z135_BASECLK               29491200
 #define MEN_Z135_FIFO_SIZE             1024
-#define MEN_Z135_NUM_MSI_VECTORS       2
 #define MEN_Z135_FIFO_WATERMARK                1020
 
 #define MEN_Z135_STAT_REG              0x0
@@ -34,12 +33,11 @@
 #define MEN_Z135_CONF_REG              0x808
 #define MEN_Z135_UART_FREQ             0x80c
 #define MEN_Z135_BAUD_REG              0x810
-#define MENZ135_TIMEOUT                        0x814
+#define MEN_Z135_TIMEOUT               0x814
 
 #define MEN_Z135_MEM_SIZE              0x818
 
-#define IS_IRQ(x) ((x) & 1)
-#define IRQ_ID(x) (((x) >> 1) & 7)
+#define IRQ_ID(x) ((x) & 0x1f)
 
 #define MEN_Z135_IER_RXCIEN BIT(0)             /* RX Space IRQ */
 #define MEN_Z135_IER_TXCIEN BIT(1)             /* TX Space IRQ */
@@ -94,11 +92,11 @@
 #define MEN_Z135_LSR_TEXP BIT(6)
 #define MEN_Z135_LSR_RXFIFOERR BIT(7)
 
-#define MEN_Z135_IRQ_ID_MST 0
-#define MEN_Z135_IRQ_ID_TSA 1
-#define MEN_Z135_IRQ_ID_RDA 2
-#define MEN_Z135_IRQ_ID_RLS 3
-#define MEN_Z135_IRQ_ID_CTI 6
+#define MEN_Z135_IRQ_ID_RLS BIT(0)
+#define MEN_Z135_IRQ_ID_RDA BIT(1)
+#define MEN_Z135_IRQ_ID_CTI BIT(2)
+#define MEN_Z135_IRQ_ID_TSA BIT(3)
+#define MEN_Z135_IRQ_ID_MST BIT(4)
 
 #define LCR(x) (((x) >> MEN_Z135_LCR_SHIFT) & 0xff)
 
@@ -118,12 +116,18 @@ static int align;
 module_param(align, int, S_IRUGO);
 MODULE_PARM_DESC(align, "Keep hardware FIFO write pointer aligned, default 0");
 
+static uint rx_timeout;
+module_param(rx_timeout, uint, S_IRUGO);
+MODULE_PARM_DESC(rx_timeout, "RX timeout. "
+               "Timeout in seconds = (timeout_reg * baud_reg * 4) / freq_reg");
+
 struct men_z135_port {
        struct uart_port port;
        struct mcb_device *mdev;
        unsigned char *rxbuf;
        u32 stat_reg;
        spinlock_t lock;
+       bool automode;
 };
 #define to_men_z135(port) container_of((port), struct men_z135_port, port)
 
@@ -180,12 +184,16 @@ static inline void men_z135_reg_clr(struct men_z135_port *uart,
  */
 static void men_z135_handle_modem_status(struct men_z135_port *uart)
 {
-       if (uart->stat_reg & MEN_Z135_MSR_DDCD)
+       u8 msr;
+
+       msr = (uart->stat_reg >> 8) & 0xff;
+
+       if (msr & MEN_Z135_MSR_DDCD)
                uart_handle_dcd_change(&uart->port,
-                               uart->stat_reg & ~MEN_Z135_MSR_DCD);
-       if (uart->stat_reg & MEN_Z135_MSR_DCTS)
+                               msr & MEN_Z135_MSR_DCD);
+       if (msr & MEN_Z135_MSR_DCTS)
                uart_handle_cts_change(&uart->port,
-                               uart->stat_reg & ~MEN_Z135_MSR_CTS);
+                               msr & MEN_Z135_MSR_CTS);
 }
 
 static void men_z135_handle_lsr(struct men_z135_port *uart)
@@ -322,7 +330,8 @@ static void men_z135_handle_tx(struct men_z135_port *uart)
 
        txfree = MEN_Z135_FIFO_WATERMARK - txc;
        if (txfree <= 0) {
-               pr_err("Not enough room in TX FIFO have %d, need %d\n",
+               dev_err(&uart->mdev->dev,
+                       "Not enough room in TX FIFO have %d, need %d\n",
                        txfree, qlen);
                goto irq_en;
        }
@@ -373,43 +382,54 @@ out:
  * @irq: The IRQ number
  * @data: Pointer to UART port
  *
- * Check IIR register to see which tasklet to start.
+ * Check IIR register to find the cause of the interrupt and handle it.
+ * It is possible that multiple interrupts reason bits are set and reading
+ * the IIR is a destructive read, so we always need to check for all possible
+ * interrupts and handle them.
  */
 static irqreturn_t men_z135_intr(int irq, void *data)
 {
        struct men_z135_port *uart = (struct men_z135_port *)data;
        struct uart_port *port = &uart->port;
+       bool handled = false;
+       unsigned long flags;
        int irq_id;
 
        uart->stat_reg = ioread32(port->membase + MEN_Z135_STAT_REG);
-       /* IRQ pending is low active */
-       if (IS_IRQ(uart->stat_reg))
-               return IRQ_NONE;
-
        irq_id = IRQ_ID(uart->stat_reg);
-       switch (irq_id) {
-       case MEN_Z135_IRQ_ID_MST:
-               men_z135_handle_modem_status(uart);
-               break;
-       case MEN_Z135_IRQ_ID_TSA:
-               men_z135_handle_tx(uart);
-               break;
-       case MEN_Z135_IRQ_ID_CTI:
-               dev_dbg(&uart->mdev->dev, "Character Timeout Indication\n");
-               /* Fallthrough */
-       case MEN_Z135_IRQ_ID_RDA:
-               /* Reading data clears RX IRQ */
-               men_z135_handle_rx(uart);
-               break;
-       case MEN_Z135_IRQ_ID_RLS:
+
+       if (!irq_id)
+               goto out;
+
+       spin_lock_irqsave(&port->lock, flags);
+       /* It's save to write to IIR[7:6] RXC[9:8] */
+       iowrite8(irq_id, port->membase + MEN_Z135_STAT_REG);
+
+       if (irq_id & MEN_Z135_IRQ_ID_RLS) {
                men_z135_handle_lsr(uart);
-               break;
-       default:
-               dev_warn(&uart->mdev->dev, "Unknown IRQ id %d\n", irq_id);
-               return IRQ_NONE;
+               handled = true;
+       }
+
+       if (irq_id & (MEN_Z135_IRQ_ID_RDA | MEN_Z135_IRQ_ID_CTI)) {
+               if (irq_id & MEN_Z135_IRQ_ID_CTI)
+                       dev_dbg(&uart->mdev->dev, "Character Timeout Indication\n");
+               men_z135_handle_rx(uart);
+               handled = true;
+       }
+
+       if (irq_id & MEN_Z135_IRQ_ID_TSA) {
+               men_z135_handle_tx(uart);
+               handled = true;
        }
 
-       return IRQ_HANDLED;
+       if (irq_id & MEN_Z135_IRQ_ID_MST) {
+               men_z135_handle_modem_status(uart);
+               handled = true;
+       }
+
+       spin_unlock_irqrestore(&port->lock, flags);
+out:
+       return IRQ_RETVAL(handled);
 }
 
 /**
@@ -464,21 +484,37 @@ static unsigned int men_z135_tx_empty(struct uart_port *port)
  */
 static void men_z135_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
-       struct men_z135_port *uart = to_men_z135(port);
-       u32 conf_reg = 0;
+       u32 old;
+       u32 conf_reg;
 
+       conf_reg = old = ioread32(port->membase + MEN_Z135_CONF_REG);
        if (mctrl & TIOCM_RTS)
                conf_reg |= MEN_Z135_MCR_RTS;
+       else
+               conf_reg &= ~MEN_Z135_MCR_RTS;
+
        if (mctrl & TIOCM_DTR)
                conf_reg |= MEN_Z135_MCR_DTR;
+       else
+               conf_reg &= ~MEN_Z135_MCR_DTR;
+
        if (mctrl & TIOCM_OUT1)
                conf_reg |= MEN_Z135_MCR_OUT1;
+       else
+               conf_reg &= ~MEN_Z135_MCR_OUT1;
+
        if (mctrl & TIOCM_OUT2)
                conf_reg |= MEN_Z135_MCR_OUT2;
+       else
+               conf_reg &= ~MEN_Z135_MCR_OUT2;
+
        if (mctrl & TIOCM_LOOP)
                conf_reg |= MEN_Z135_MCR_LOOP;
+       else
+               conf_reg &= ~MEN_Z135_MCR_LOOP;
 
-       men_z135_reg_set(uart, MEN_Z135_CONF_REG, conf_reg);
+       if (conf_reg != old)
+               iowrite32(conf_reg, port->membase + MEN_Z135_CONF_REG);
 }
 
 /**
@@ -490,12 +526,9 @@ static void men_z135_set_mctrl(struct uart_port *port, unsigned int mctrl)
 static unsigned int men_z135_get_mctrl(struct uart_port *port)
 {
        unsigned int mctrl = 0;
-       u32 stat_reg;
        u8 msr;
 
-       stat_reg = ioread32(port->membase + MEN_Z135_STAT_REG);
-
-       msr = ~((stat_reg >> 8) & 0xff);
+       msr = ioread8(port->membase + MEN_Z135_STAT_REG + 1);
 
        if (msr & MEN_Z135_MSR_CTS)
                mctrl |= TIOCM_CTS;
@@ -524,6 +557,19 @@ static void men_z135_stop_tx(struct uart_port *port)
        men_z135_reg_clr(uart, MEN_Z135_CONF_REG, MEN_Z135_IER_TXCIEN);
 }
 
+/*
+ * men_z135_disable_ms() - Disable Modem Status
+ * port: The UART port
+ *
+ * Enable Modem Status IRQ.
+ */
+static void men_z135_disable_ms(struct uart_port *port)
+{
+       struct men_z135_port *uart = to_men_z135(port);
+
+       men_z135_reg_clr(uart, MEN_Z135_CONF_REG, MEN_Z135_IER_MSIEN);
+}
+
 /**
  * men_z135_start_tx() - Start transmitting characters
  * @port: The UART port
@@ -535,6 +581,9 @@ static void men_z135_start_tx(struct uart_port *port)
 {
        struct men_z135_port *uart = to_men_z135(port);
 
+       if (uart->automode)
+               men_z135_disable_ms(port);
+
        men_z135_handle_tx(uart);
 }
 
@@ -584,6 +633,9 @@ static int men_z135_startup(struct uart_port *port)
 
        iowrite32(conf_reg, port->membase + MEN_Z135_CONF_REG);
 
+       if (rx_timeout)
+               iowrite32(rx_timeout, port->membase + MEN_Z135_TIMEOUT);
+
        return 0;
 }
 
@@ -603,6 +655,7 @@ static void men_z135_set_termios(struct uart_port *port,
                                struct ktermios *termios,
                                struct ktermios *old)
 {
+       struct men_z135_port *uart = to_men_z135(port);
        unsigned int baud;
        u32 conf_reg;
        u32 bd_reg;
@@ -643,6 +696,16 @@ static void men_z135_set_termios(struct uart_port *port,
        } else
                lcr |= MEN_Z135_PAR_DIS << MEN_Z135_PEN_SHIFT;
 
+       conf_reg |= MEN_Z135_IER_MSIEN;
+       if (termios->c_cflag & CRTSCTS) {
+               conf_reg |= MEN_Z135_MCR_RCFC;
+               uart->automode = true;
+               termios->c_cflag &= ~CLOCAL;
+       } else {
+               conf_reg &= ~MEN_Z135_MCR_RCFC;
+               uart->automode = false;
+       }
+
        termios->c_cflag &= ~CMSPAR; /* Mark/Space parity is not supported */
 
        conf_reg |= lcr << MEN_Z135_LCR_SHIFT;