imx: serial: add IrDA support to serial driver

Using the iMX serial driver with an IrDA device
needs extra peripheral settings and specific
timing depending on the transmitter circuitry used.

Signed-off-by: Fabian Godehardt <fg@emlix.com>
Signed-off-by: Oskar Schirmer <os@emlix.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 176 insertions, 19 deletions

diff --git a/drivers/serial/imx.c b/drivers/serial/imx.c
index 0de81f71f884..8c79e8c2fd4e 100644
--- a/drivers/serial/imx.c
+++ b/drivers/serial/imx.c
@@ -8,6 +8,9 @@
  *  Author: Sascha Hauer <sascha@saschahauer.de>
  *  Copyright (C) 2004 Pengutronix
  *
+ *  Copyright (C) 2009 emlix GmbH
+ *  Author: Fabian Godehardt (added IrDA support for iMX)
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
@@ -41,6 +44,7 @@
 #include <linux/serial_core.h>
 #include <linux/serial.h>
 #include <linux/clk.h>
+#include <linux/delay.h>
 #include <linux/rational.h>
 
 #include <asm/io.h>
@@ -149,6 +153,7 @@
 #define  UCR4_DREN       (1<<0)  /* Recv data ready interrupt enable */
 #define  UFCR_RXTL_SHF   0       /* Receiver trigger level shift */
 #define  UFCR_RFDIV      (7<<7)  /* Reference freq divider mask */
+#define  UFCR_RFDIV_REG(x)      (((x) < 7 ? 6 - (x) : 6) << 7)
 #define  UFCR_TXTL_SHF   10      /* Transmitter trigger level shift */
 #define  USR1_PARITYERR  (1<<15) /* Parity error interrupt flag */
 #define  USR1_RTSS       (1<<14) /* RTS pin status */
@@ -213,9 +218,19 @@ struct imx_port {
         unsigned int            old_status;
         int                     txirq,rxirq,rtsirq;
         unsigned int            have_rtscts:1;
+        unsigned int            use_irda:1;
+        unsigned int            irda_inv_rx:1;
+        unsigned int            irda_inv_tx:1;
+        unsigned short          trcv_delay; /* transceiver delay */
         struct clk              *clk;
 };
 
+#ifdef CONFIG_IRDA
+#define USE_IRDA(sport) ((sport)->use_irda)
+#else
+#define USE_IRDA(sport) (0)
+#endif
+
 /*
  * Handle any change of modem status signal since we were last called.
  */
@@ -269,6 +284,48 @@ static void imx_stop_tx(struct uart_port *port)
         struct imx_port *sport = (struct imx_port *)port;
         unsigned long temp;
 
+        if (USE_IRDA(sport)) {
+                /* half duplex - wait for end of transmission */
+                int n = 256;
+                while ((--n > 0) &&
+                      !(readl(sport->port.membase + USR2) & USR2_TXDC)) {
+                        udelay(5);
+                        barrier();
+                }
+                /*
+                 * irda transceiver - wait a bit more to avoid
+                 * cutoff, hardware dependent
+                 */
+                udelay(sport->trcv_delay);
+
+                /*
+                 * half duplex - reactivate receive mode,
+                 * flush receive pipe echo crap
+                 */
+                if (readl(sport->port.membase + USR2) & USR2_TXDC) {
+                        temp = readl(sport->port.membase + UCR1);
+                        temp &= ~(UCR1_TXMPTYEN | UCR1_TRDYEN);
+                        writel(temp, sport->port.membase + UCR1);
+
+                        temp = readl(sport->port.membase + UCR4);
+                        temp &= ~(UCR4_TCEN);
+                        writel(temp, sport->port.membase + UCR4);
+
+                        while (readl(sport->port.membase + URXD0) &
+                               URXD_CHARRDY)
+                                barrier();
+
+                        temp = readl(sport->port.membase + UCR1);
+                        temp |= UCR1_RRDYEN;
+                        writel(temp, sport->port.membase + UCR1);
+
+                        temp = readl(sport->port.membase + UCR4);
+                        temp |= UCR4_DREN;
+                        writel(temp, sport->port.membase + UCR4);
+                }
+                return;
+        }
+
         temp = readl(sport->port.membase + UCR1);
         writel(temp & ~UCR1_TXMPTYEN, sport->port.membase + UCR1);
 }
@@ -324,9 +381,30 @@ static void imx_start_tx(struct uart_port *port)
         struct imx_port *sport = (struct imx_port *)port;
         unsigned long temp;
 
+        if (USE_IRDA(sport)) {
+                /* half duplex in IrDA mode; have to disable receive mode */
+                temp = readl(sport->port.membase + UCR4);
+                temp &= ~(UCR4_DREN);
+                writel(temp, sport->port.membase + UCR4);
+
+                temp = readl(sport->port.membase + UCR1);
+                temp &= ~(UCR1_RRDYEN);
+                writel(temp, sport->port.membase + UCR1);
+        }
+
         temp = readl(sport->port.membase + UCR1);
         writel(temp | UCR1_TXMPTYEN, sport->port.membase + UCR1);
 
+        if (USE_IRDA(sport)) {
+                temp = readl(sport->port.membase + UCR1);
+                temp |= UCR1_TRDYEN;
+                writel(temp, sport->port.membase + UCR1);
+
+                temp = readl(sport->port.membase + UCR4);
+                temp |= UCR4_TCEN;
+                writel(temp, sport->port.membase + UCR4);
+        }
+
         if (readl(sport->port.membase + UTS) & UTS_TXEMPTY)
                 imx_transmit_buffer(sport);
 }
@@ -536,12 +614,7 @@ static int imx_setup_ufcr(struct imx_port *sport, unsigned int mode)
         if(!ufcr_rfdiv)
                 ufcr_rfdiv = 1;
 
-        if(ufcr_rfdiv >= 7)
-                ufcr_rfdiv = 6;
-        else
-                ufcr_rfdiv = 6 - ufcr_rfdiv;
-
-        val |= UFCR_RFDIV & (ufcr_rfdiv << 7);
+        val |= UFCR_RFDIV_REG(ufcr_rfdiv);
 
         writel(val, sport->port.membase + UFCR);
 
@@ -560,8 +633,24 @@ static int imx_startup(struct uart_port *port)
          * requesting IRQs
          */
         temp = readl(sport->port.membase + UCR4);
+
+        if (USE_IRDA(sport))
+                temp |= UCR4_IRSC;
+
         writel(temp & ~UCR4_DREN, sport->port.membase + UCR4);
 
+        if (USE_IRDA(sport)) {
+                /* reset fifo's and state machines */
+                int i = 100;
+                temp = readl(sport->port.membase + UCR2);
+                temp &= ~UCR2_SRST;
+                writel(temp, sport->port.membase + UCR2);
+                while (!(readl(sport->port.membase + UCR2) & UCR2_SRST) &&
+                    (--i > 0)) {
+                        udelay(1);
+                }
+        }
+
         /*
          * Allocate the IRQ(s) i.MX1 has three interrupts whereas later
          * chips only have one interrupt.
@@ -577,12 +666,16 @@ static int imx_startup(struct uart_port *port)
                 if (retval)
                         goto error_out2;
 
-                retval = request_irq(sport->rtsirq, imx_rtsint,
-                             (sport->rtsirq < MAX_INTERNAL_IRQ) ? 0 :
-                               IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING,
-                                DRIVER_NAME, sport);
-                if (retval)
-                        goto error_out3;
+                /* do not use RTS IRQ on IrDA */
+                if (!USE_IRDA(sport)) {
+                        retval = request_irq(sport->rtsirq, imx_rtsint,
+                                     (sport->rtsirq < MAX_INTERNAL_IRQ) ? 0 :
+                                       IRQF_TRIGGER_FALLING |
+                                       IRQF_TRIGGER_RISING,
+                                        DRIVER_NAME, sport);
+                        if (retval)
+                                goto error_out3;
+                }
         } else {
                 retval = request_irq(sport->port.irq, imx_int, 0,
                                 DRIVER_NAME, sport);
@@ -599,18 +692,49 @@ static int imx_startup(struct uart_port *port)
 
         temp = readl(sport->port.membase + UCR1);
         temp |= UCR1_RRDYEN | UCR1_RTSDEN | UCR1_UARTEN;
+
+        if (USE_IRDA(sport)) {
+                temp |= UCR1_IREN;
+                temp &= ~(UCR1_RTSDEN);
+        }
+
         writel(temp, sport->port.membase + UCR1);
 
         temp = readl(sport->port.membase + UCR2);
         temp |= (UCR2_RXEN | UCR2_TXEN);
         writel(temp, sport->port.membase + UCR2);
 
+        if (USE_IRDA(sport)) {
+                /* clear RX-FIFO */
+                int i = 64;
+                while ((--i > 0) &&
+                        (readl(sport->port.membase + URXD0) & URXD_CHARRDY)) {
+                        barrier();
+                }
+        }
+
 #if defined CONFIG_ARCH_MX2 || defined CONFIG_ARCH_MX3
         temp = readl(sport->port.membase + UCR3);
         temp |= UCR3_RXDMUXSEL;
         writel(temp, sport->port.membase + UCR3);
 #endif
 
+        if (USE_IRDA(sport)) {
+                temp = readl(sport->port.membase + UCR4);
+                if (sport->irda_inv_rx)
+                        temp |= UCR4_INVR;
+                else
+                        temp &= ~(UCR4_INVR);
+                writel(temp | UCR4_DREN, sport->port.membase + UCR4);
+
+                temp = readl(sport->port.membase + UCR3);
+                if (sport->irda_inv_tx)
+                        temp |= UCR3_INVT;
+                else
+                        temp &= ~(UCR3_INVT);
+                writel(temp, sport->port.membase + UCR3);
+        }
+
         /*
          * Enable modem status interrupts
          */
@@ -618,6 +742,16 @@ static int imx_startup(struct uart_port *port)
         imx_enable_ms(&sport->port);
         spin_unlock_irqrestore(&sport->port.lock,flags);
 
+        if (USE_IRDA(sport)) {
+                struct imxuart_platform_data *pdata;
+                pdata = sport->port.dev->platform_data;
+                sport->irda_inv_rx = pdata->irda_inv_rx;
+                sport->irda_inv_tx = pdata->irda_inv_tx;
+                sport->trcv_delay = pdata->transceiver_delay;
+                if (pdata->irda_enable)
+                        pdata->irda_enable(1);
+        }
+
         return 0;
 
 error_out3:
@@ -639,6 +773,13 @@ static void imx_shutdown(struct uart_port *port)
         temp &= ~(UCR2_TXEN);
         writel(temp, sport->port.membase + UCR2);
 
+        if (USE_IRDA(sport)) {
+                struct imxuart_platform_data *pdata;
+                pdata = sport->port.dev->platform_data;
+                if (pdata->irda_enable)
+                        pdata->irda_enable(0);
+        }
+
         /*
          * Stop our timer.
          */
@@ -648,7 +789,8 @@ static void imx_shutdown(struct uart_port *port)
          * Free the interrupts
          */
         if (sport->txirq > 0) {
-                free_irq(sport->rtsirq, sport);
+                if (!USE_IRDA(sport))
+                        free_irq(sport->rtsirq, sport);
                 free_irq(sport->txirq, sport);
                 free_irq(sport->rxirq, sport);
         } else
@@ -660,6 +802,9 @@ static void imx_shutdown(struct uart_port *port)
 
         temp = readl(sport->port.membase + UCR1);
         temp &= ~(UCR1_TXMPTYEN | UCR1_RRDYEN | UCR1_RTSDEN | UCR1_UARTEN);
+        if (USE_IRDA(sport))
+                temp &= ~(UCR1_IREN);
+
         writel(temp, sport->port.membase + UCR1);
 }
 
@@ -768,11 +913,19 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios,
                         sport->port.membase + UCR2);
         old_txrxen &= (UCR2_TXEN | UCR2_RXEN);
 
-        div = sport->port.uartclk / (baud * 16);
-        if (div > 7)
-                div = 7;
-        if (!div)
+        if (USE_IRDA(sport)) {
+                /*
+                 * use maximum available submodule frequency to
+                 * avoid missing short pulses due to low sampling rate
+                 */
                 div = 1;
+        } else {
+                div = sport->port.uartclk / (baud * 16);
+                if (div > 7)
+                        div = 7;
+                if (!div)
+                        div = 1;
+        }
 
         rational_best_approximation(16 * div * baud, sport->port.uartclk,
                 1 << 16, 1 << 16, &num, &denom);
@@ -781,8 +934,7 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios,
         denom -= 1;
 
         ufcr = readl(sport->port.membase + UFCR);
-        ufcr = (ufcr & (~UFCR_RFDIV)) |
-            (div << 7);
+        ufcr = (ufcr & (~UFCR_RFDIV)) | UFCR_RFDIV_REG(div);
         writel(ufcr, sport->port.membase + UFCR);
 
         writel(num, sport->port.membase + UBIR);
@@ -1141,6 +1293,11 @@ static int serial_imx_probe(struct platform_device *pdev)
         if (pdata && (pdata->flags & IMXUART_HAVE_RTSCTS))
                 sport->have_rtscts = 1;
 
+#ifdef CONFIG_IRDA
+        if (pdata && (pdata->flags & IMXUART_IRDA))
+                sport->use_irda = 1;
+#endif
+
         if (pdata->init) {
                 ret = pdata->init(pdev);
                 if (ret)