Hi,
I make PATCH for the 16550A serial drivers.
It allow to assert RTS signal during transmit in EIA-485 half duplex
mode for 16550A compatible controllers.
I have also modified the libmodbus-2.0.3 to be used with xenomai if
anyone is intesested// in this lib, please let me know
Thanks, Alexandre
--
Alexandre COFFIGNAL, Chef de Projet
Email: alexandre.coffig...@cenosys.com
<mailto:alexandre.coffig...@cenosys.com>
------------------------------------
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Tel: +33(0) 243 511 797
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>From 0aa88d5d4fe5ab43f3069ab4dc8125d4a866f24c Mon Sep 17 00:00:00 2001
From: Alexandre Coffignal <alexandre.coffig...@cenosys.com>
Date: Wed, 20 Jan 2010 15:13:39 +0100
Subject: [PATCH] rtdm : Allow to assert RTS signal during transmit in EIA-485 half duplex
mode for 16550A compatible controllers.
---
include/rtdm/rtserial.h | 34 ++++++++++++
ksrc/drivers/serial/16550A.c | 115 ++++++++++++++++++++++++++++++++++++++++-
ksrc/drivers/serial/Kconfig | 7 +++
3 files changed, 153 insertions(+), 3 deletions(-)
diff --git a/include/rtdm/rtserial.h b/include/rtdm/rtserial.h
index 48712b2..3a7b091 100644
--- a/include/rtdm/rtserial.h
+++ b/include/rtdm/rtserial.h
@@ -127,8 +127,13 @@
#define RTSER_NO_HAND 0x00
#define RTSER_RTSCTS_HAND 0x01
#define RTSER_DEF_HAND RTSER_NO_HAND
+#ifdef CONFIG_XENO_DRIVERS_16550A_RS485_HALF
+#define RTSER_RTS_RS485_HALF 0x02
+#endif
/** @} */
+
+
/*!
* @anchor RTSER_FIFO_xxx @name RTSER_FIFO_xxx
* Reception FIFO interrupt threshold
@@ -503,4 +508,33 @@ typedef struct rtser_event {
/** @} */
+#ifdef CONFIG_XENO_DRIVERS_16550A_RS485_HALF
+
+typedef struct rs485_config
+{
+ nanosecs_rel_t delay_after_send;
+}rs485_config_t;
+
+#define RS485_DEF_DELAY_AFTER_SEND 100000 //100uS
+
+/**
+ * Set config for rs485 half duplex mode
+ *
+ * @param[in] arg New rs485 config content
+ *
+ * @return 0 on success, otherwise negative error code
+ *
+ * Environments:
+ *
+ * This service can be called from:
+ *
+ * - Kernel module initialization/cleanup code
+ * - Kernel-based task
+ * - User-space task (RT, non-RT)
+ *
+ * Rescheduling: never.
+ */
+#define RTSER_RTIOC_RS485_SET_CONFIG \
+ _IOW(RTIOC_TYPE_SERIAL, 0x07, struct rs485_config)
+#endif
#endif /* _RTSERIAL_H */
diff --git a/ksrc/drivers/serial/16550A.c b/ksrc/drivers/serial/16550A.c
index db8a515..45c5cc3 100644
--- a/ksrc/drivers/serial/16550A.c
+++ b/ksrc/drivers/serial/16550A.c
@@ -107,6 +107,12 @@ struct rt_16550_context {
int mcr_status; /* MCR cache */
int status; /* cache for LSR + soft-states */
int saved_errors; /* error cache for RTIOC_GET_STATUS */
+#ifdef CONFIG_XENO_DRIVERS_16550A_RS485_HALF
+ size_t bytes_send; /* bytes sent on last tx it*/
+ rtdm_task_t rts_task; /* task used to assert RTS signal during transmit(rs485)*/
+ rtdm_sem_t itTx; /* raised to unblock rts task (rs485) */
+ rs485_config_t rs485_config; /* delay after TX frame before rts down in nanosecond(rs485) */
+#endif
};
static const struct rtser_config default_config = {
@@ -204,8 +210,16 @@ static inline void rt_16550_tx_interrupt(struct rt_16550_context *ctx)
ctx->out_head &= (OUT_BUFFER_SIZE - 1);
}
}
-}
+#ifdef CONFIG_XENO_DRIVERS_16550A_RS485_HALF
+ if(ctx->config.handshake==RTSER_RTS_RS485_HALF)
+ {
+ /* up to unblock rts task in rs485 half duplex mode */
+ ctx->bytes_send=ctx->tx_fifo-count;
+ rtdm_sem_up(&ctx->itTx);
+ }
+#endif
+}
static inline void rt_16550_stat_interrupt(struct rt_16550_context *ctx)
{
unsigned long base = ctx->base_addr;
@@ -409,10 +423,15 @@ static int rt_16550_set_config(struct rt_16550_context *ctx,
if (testbits(config->config_mask, RTSER_SET_HANDSHAKE)) {
/* change handshake atomically */
rtdm_lock_get_irqsave(&ctx->lock, lock_ctx);
-
ctx->config.handshake = config->handshake;
switch (ctx->config.handshake) {
+#ifdef CONFIG_XENO_DRIVERS_16550A_RS485_HALF
+ case RTSER_RTS_RS485_HALF:
+ ctx->mcr_status =
+ RTSER_MCR_DTR | RTSER_MCR_RTS | RTSER_MCR_OUT2;
+ break;
+#endif
case RTSER_RTSCTS_HAND:
// ...?
@@ -437,6 +456,51 @@ void rt_16550_cleanup_ctx(struct rt_16550_context *ctx)
rtdm_mutex_destroy(&ctx->out_lock);
}
+#ifdef CONFIG_XENO_DRIVERS_16550A_RS485_HALF
+#define RTS_STD_PRIO 1
+
+/* RS485
+ * allow to put in transmit mode explicitly by asserting RTC signal to the driver during
+ * transmission
+ *
+ * This allows EIA-485 to implement linear topologies using only two wires
+ *
+ */
+void rts_task(void *arg)
+{
+ struct rt_16550_context *ctx= (struct rt_16550_context *)arg;
+ int ret;
+ nanosecs_rel_t delay ;
+ char event=1;
+
+ while(1){
+ //wait sem up from itTx
+ ret =rtdm_sem_down (&ctx->itTx);
+ if(ret)
+ printk("error rts_task... sem down error %d\n",ret);
+
+ do{
+ //wait end of transmission nbit + * fifo size / baud rate
+ delay=11*ctx->bytes_send*1000000/ctx->config.baud_rate;
+ ret=rtdm_sem_timeddown(&ctx->itTx, delay*1000+ctx->rs485_config.delay_after_send,NULL);
+ if(ret){
+ if(ret!=-ETIMEDOUT){
+ printk("error rts_task rtdm_event_timedwait... error %d\n",ret);
+ }
+ //no new rtdm event itTx receive during the transfert
+ event=0;
+ }
+ else//new rtdm event itTx receive during the transfert, still waiting
+ event=1;
+
+ }while(event);
+ //down RTS
+ ctx->mcr_status &= ~RTSER_MCR_RTS;
+ rt_16550_reg_out(rt_16550_io_mode_from_ctx(ctx),ctx->base_addr, MCR, ctx->mcr_status);
+ }
+}
+#endif
+
int rt_16550_open(struct rtdm_dev_context *context,
rtdm_user_info_t * user_info, int oflags)
{
@@ -458,7 +522,9 @@ int rt_16550_open(struct rtdm_dev_context *context,
rt_16550_init_io_ctx(dev_id, ctx);
ctx->tx_fifo = tx_fifo[dev_id];
-
+#ifdef CONFIG_XENO_DRIVERS_16550A_RS485_HALF
+ ctx->rs485_config.delay_after_send=RS485_DEF_DELAY_AFTER_SEND;
+#endif
ctx->in_head = 0;
ctx->in_tail = 0;
ctx->in_npend = 0;
@@ -475,6 +541,7 @@ int rt_16550_open(struct rtdm_dev_context *context,
ctx->status = 0;
ctx->saved_errors = 0;
+
rt_16550_set_config(ctx, &default_config, &dummy);
err = rtdm_irq_request(&ctx->irq_handle, irq[dev_id],
@@ -493,6 +560,17 @@ int rt_16550_open(struct rtdm_dev_context *context,
rtdm_lock_get_irqsave(&ctx->lock, lock_ctx);
+#ifdef CONFIG_XENO_DRIVERS_16550A_RS485_HALF
+ /* create semaphore used to unblock rts_task (rs485)*/
+ rtdm_sem_init(&ctx->itTx, 0);
+ /* create task used to assert RTS signal during transmit in (rs485)*/
+ err = rtdm_task_init(&ctx->rts_task, "rts_task", &rts_task, ctx, RTS_STD_PRIO, 0);
+ if (err) {
+ printk("error rtdm_task_init\n");
+ return 0;
+ }
+#endif
+
/* enable interrupts */
ctx->ier_status = IER_RX;
rt_16550_reg_out(rt_16550_io_mode_from_ctx(ctx), ctx->base_addr, IER,
@@ -535,6 +613,11 @@ int rt_16550_close(struct rtdm_dev_context *context,
rtdm_irq_free(&ctx->irq_handle);
+#ifdef CONFIG_XENO_DRIVERS_16550A_RS485_HALF
+ rtdm_sem_destroy(&ctx->itTx);
+ rtdm_task_destroy(&ctx->rts_task);
+#endif
+
rt_16550_cleanup_ctx(ctx);
if (in_history) {
@@ -802,6 +885,24 @@ int rt_16550_ioctl(struct rtdm_dev_context *context,
rtdm_lock_put_irqrestore(&ctx->lock, lock_ctx);
break;
}
+#ifdef CONFIG_XENO_DRIVERS_16550A_RS485_HALF
+ case RTSER_RTIOC_RS485_SET_CONFIG: {
+ struct rs485_config *config;
+ struct rs485_config config_buf;
+ config = (struct rtser_config *)arg;
+ if (user_info) {
+ err = rtdm_safe_copy_from_user(user_info, &config_buf,
+ arg,
+ sizeof(struct rs485_config));
+ if (err)
+ return err;
+
+ config = &config_buf;
+ ctx->rs485_config.delay_after_send=config->delay_after_send;
+ }
+ break;
+#endif
+ }
default:
err = -ENOTTY;
@@ -1005,6 +1106,14 @@ ssize_t rt_16550_write(struct rtdm_dev_context * context,
if (ret)
return ret;
+#ifdef CONFIG_XENO_DRIVERS_16550A_RS485_HALF
+ if(ctx->config.handshake==RTSER_RTS_RS485_HALF)
+ {
+ //assert RTS signal during transmit in rs485 half duplex mode
+ ctx->mcr_status |= RTSER_MCR_RTS;
+ rt_16550_reg_out(rt_16550_io_mode_from_ctx(ctx),ctx->base_addr, MCR, ctx->mcr_status);
+ }
+#endif
while (nbyte > 0) {
rtdm_lock_get_irqsave(&ctx->lock, lock_ctx);
diff --git a/ksrc/drivers/serial/Kconfig b/ksrc/drivers/serial/Kconfig
index afbaabf..95337bf 100644
--- a/ksrc/drivers/serial/Kconfig
+++ b/ksrc/drivers/serial/Kconfig
@@ -39,4 +39,11 @@ config XENO_DRIVERS_16550A_ANY
endchoice
+config XENO_DRIVERS_16550A_RS485_HALF
+ depends on XENO_DRIVERS_16550A
+ bool "EIA-485 half duplex"
+ help
+ Assert RTS signal during transmit in EIA-485 half duplex mode
+ for 16550A compatible controllers.
+
endmenu
--
1.6.0.4
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