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Subject[PATCH 8/9 -v2] imx: serial: add IrDA support to serial driver
Date
From: Fabian Godehardt <fg@emlix.com>

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>
---
arch/arm/plat-mxc/include/mach/imx-uart.h | 5 +
drivers/serial/imx.c | 195 ++++++++++++++++++++++++++---
2 files changed, 181 insertions(+), 19 deletions(-)
diff --git a/arch/arm/plat-mxc/include/mach/imx-uart.h b/arch/arm/plat-mxc/include/mach/imx-uart.h
index 599217b..f9bd17d 100644
--- a/arch/arm/plat-mxc/include/mach/imx-uart.h
+++ b/arch/arm/plat-mxc/include/mach/imx-uart.h
@@ -20,11 +20,16 @@
#define ASMARM_ARCH_UART_H

#define IMXUART_HAVE_RTSCTS (1<<0)
+#define IMXUART_IRDA (1<<1)

struct imxuart_platform_data {
int (*init)(struct platform_device *pdev);
int (*exit)(struct platform_device *pdev);
unsigned int flags;
+ void (*irda_enable)(int enable);
+ unsigned int irda_inv_rx:1;
+ unsigned int irda_inv_tx:1;
+ unsigned short transceiver_delay;
};

#endif
diff --git a/drivers/serial/imx.c b/drivers/serial/imx.c
index 11f93e2..1c00e2a 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);
@@ -1139,6 +1291,11 @@ 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)
--
1.5.3.7


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