Changes from v4:
- Add commit message to 1/3
Changes from v3:
- Completely redesigned.
Changes from v2:
- Introduced SER_RS485_SOFTWARE to show that software implementation is being used
- serial8250_rs485_config is located as required
- Timers are used to implement delay_before and delay_after timeouts
Software RS485 emultaion is to be added in the following commit.
serial8250_start_tx will need to refer serial8250_stop_rx.
Move serial8250_stop_rx in front of serial8250_start_tx in order
to avoid function forward declaration.
Signed-off-by: Matwey V. Kornilov <[email protected]>
---
drivers/tty/serial/8250/8250_port.c | 26 +++++++++++++-------------
1 file changed, 13 insertions(+), 13 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 0bbf340..8ad0b2d 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1280,6 +1280,19 @@ static void autoconfig_irq(struct uart_8250_port *up)
port->irq = (irq > 0) ? irq : 0;
}
+static void serial8250_stop_rx(struct uart_port *port)
+{
+ struct uart_8250_port *up = up_to_u8250p(port);
+
+ serial8250_rpm_get(up);
+
+ up->ier &= ~(UART_IER_RLSI | UART_IER_RDI);
+ up->port.read_status_mask &= ~UART_LSR_DR;
+ serial_port_out(port, UART_IER, up->ier);
+
+ serial8250_rpm_put(up);
+}
+
static inline void __stop_tx(struct uart_8250_port *p)
{
if (p->ier & UART_IER_THRI) {
@@ -1347,19 +1360,6 @@ static void serial8250_unthrottle(struct uart_port *port)
port->unthrottle(port);
}
-static void serial8250_stop_rx(struct uart_port *port)
-{
- struct uart_8250_port *up = up_to_u8250p(port);
-
- serial8250_rpm_get(up);
-
- up->ier &= ~(UART_IER_RLSI | UART_IER_RDI);
- up->port.read_status_mask &= ~UART_LSR_DR;
- serial_port_out(port, UART_IER, up->ier);
-
- serial8250_rpm_put(up);
-}
-
static void serial8250_disable_ms(struct uart_port *port)
{
struct uart_8250_port *up =
--
2.6.3
Implementation of software emulation of RS485 direction handling is based
on omap_serial driver.
Before and after transmission RTS is set to the appropriate value.
Note that before calling serial8250_em485_init the caller has to
ensure that UART will interrupt when shift register empty. Otherwise,
emultaion cannot be used.
Both serial8250_em485_init and serial8250_em485_destroy are
idempotent functions.
Signed-off-by: Matwey V. Kornilov <[email protected]>
---
drivers/tty/serial/8250/8250.h | 6 ++
drivers/tty/serial/8250/8250_port.c | 161 +++++++++++++++++++++++++++++++++++-
include/linux/serial_8250.h | 7 ++
3 files changed, 170 insertions(+), 4 deletions(-)
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index d54dcd8..a3816c6 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -117,6 +117,12 @@ static inline void serial_dl_write(struct uart_8250_port *up, int value)
struct uart_8250_port *serial8250_get_port(int line);
void serial8250_rpm_get(struct uart_8250_port *p);
void serial8250_rpm_put(struct uart_8250_port *p);
+int serial8250_em485_init(struct uart_8250_port *p);
+void serial8250_em485_destroy(struct uart_8250_port *p);
+static inline bool serial8250_em485_enabled(struct uart_8250_port *p)
+{
+ return p->rs485_emul && (p->port.rs485.flags & SER_RS485_ENABLED);
+}
#if defined(__alpha__) && !defined(CONFIG_PCI)
/*
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 8ad0b2d..394d0d2 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -37,6 +37,7 @@
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/pm_runtime.h>
+#include <linux/timer.h>
#include <asm/io.h>
#include <asm/irq.h>
@@ -504,6 +505,31 @@ static void serial8250_clear_fifos(struct uart_8250_port *p)
}
}
+static inline void serial8250_em485_rts_on_send(struct uart_8250_port *p)
+{
+ unsigned char mcr = serial_in(p, UART_MCR);
+
+ if (p->port.rs485.flags & SER_RS485_RTS_ON_SEND)
+ mcr |= UART_MCR_RTS;
+ else
+ mcr &= ~UART_MCR_RTS;
+ serial_out(p, UART_MCR, mcr);
+}
+
+static inline void serial8250_em485_rts_after_send(struct uart_8250_port *p)
+{
+ unsigned char mcr = serial_in(p, UART_MCR);
+
+ if (p->port.rs485.flags & SER_RS485_RTS_AFTER_SEND)
+ mcr |= UART_MCR_RTS;
+ else
+ mcr &= ~UART_MCR_RTS;
+ serial_out(p, UART_MCR, mcr);
+}
+
+static void serial8250_em485_handle_start_tx(unsigned long arg);
+static void serial8250_em485_handle_stop_tx(unsigned long arg);
+
void serial8250_clear_and_reinit_fifos(struct uart_8250_port *p)
{
serial8250_clear_fifos(p);
@@ -528,6 +554,42 @@ void serial8250_rpm_put(struct uart_8250_port *p)
}
EXPORT_SYMBOL_GPL(serial8250_rpm_put);
+int serial8250_em485_init(struct uart_8250_port *p)
+{
+ if (p->rs485_emul != NULL)
+ return 0;
+
+ p->rs485_emul = kmalloc(sizeof(struct uart_8250_rs485_emul), GFP_KERNEL);
+ if (p->rs485_emul == NULL)
+ return -ENOMEM;
+
+ init_timer(&p->rs485_emul->stop_tx_timer);
+ p->rs485_emul->stop_tx_timer.function = serial8250_em485_handle_stop_tx;
+ p->rs485_emul->stop_tx_timer.data = (unsigned long)p;
+ p->rs485_emul->stop_tx_timer.flags |= TIMER_IRQSAFE;
+ init_timer(&p->rs485_emul->start_tx_timer);
+ p->rs485_emul->start_tx_timer.function = serial8250_em485_handle_start_tx;
+ p->rs485_emul->start_tx_timer.data = (unsigned long)p;
+ p->rs485_emul->start_tx_timer.flags |= TIMER_IRQSAFE;
+
+ serial8250_em485_rts_after_send(p);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(serial8250_em485_init);
+void serial8250_em485_destroy(struct uart_8250_port *p)
+{
+ if (p->rs485_emul == NULL)
+ return;
+
+ del_timer_sync(&p->rs485_emul->start_tx_timer);
+ del_timer_sync(&p->rs485_emul->stop_tx_timer);
+
+ kfree(p->rs485_emul);
+ p->rs485_emul = NULL;
+}
+EXPORT_SYMBOL_GPL(serial8250_em485_destroy);
+
/*
* These two wrappers ensure that enable_runtime_pm_tx() can be called more than
* once and disable_runtime_pm_tx() will still disable RPM because the fifo is
@@ -1293,7 +1355,61 @@ static void serial8250_stop_rx(struct uart_port *port)
serial8250_rpm_put(up);
}
-static inline void __stop_tx(struct uart_8250_port *p)
+static __u32 __start_tx_rs485(struct uart_8250_port *p)
+{
+ if (!serial8250_em485_enabled(p))
+ return 0;
+
+ if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX))
+ serial8250_stop_rx(&p->port);
+
+ del_timer_sync(&p->rs485_emul->stop_tx_timer);
+
+ if (!!(p->port.rs485.flags & SER_RS485_RTS_ON_SEND) != !!(serial_in(p, UART_MCR) & UART_MCR_RTS)) {
+ serial8250_em485_rts_on_send(p);
+ return p->port.rs485.delay_rts_before_send;
+ }
+
+ return 0;
+}
+
+static inline void __do_stop_tx_rs485(struct uart_8250_port *p)
+{
+ if (!serial8250_em485_enabled(p))
+ return;
+
+ serial8250_em485_rts_after_send(p);
+ /*
+ * Empty the RX FIFO, we are not interested in anything
+ * received during the half-duplex transmission.
+ */
+ if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX))
+ serial8250_clear_fifos(p);
+}
+
+static void serial8250_em485_handle_stop_tx(unsigned long arg)
+{
+ struct uart_8250_port *p = (struct uart_8250_port *)arg;
+
+ __do_stop_tx_rs485(p);
+}
+
+static inline void __stop_tx_rs485(struct uart_8250_port *p)
+{
+ if (!serial8250_em485_enabled(p))
+ return;
+
+ del_timer_sync(&p->rs485_emul->start_tx_timer);
+
+ /* __do_stop_tx_rs485 is going to set RTS according to config AND flush RX FIFO if required */
+ if (p->port.rs485.delay_rts_after_send > 0) {
+ mod_timer(&p->rs485_emul->stop_tx_timer, jiffies + p->port.rs485.delay_rts_after_send * HZ / 1000);
+ } else {
+ __do_stop_tx_rs485(p);
+ }
+}
+
+static inline void __do_stop_tx(struct uart_8250_port *p)
{
if (p->ier & UART_IER_THRI) {
p->ier &= ~UART_IER_THRI;
@@ -1302,6 +1418,21 @@ static inline void __stop_tx(struct uart_8250_port *p)
}
}
+static inline void __stop_tx(struct uart_8250_port *p)
+{
+ if (serial8250_em485_enabled(p)) {
+ unsigned char lsr = serial_in(p, UART_LSR);
+ /* To provide required timeing and allow FIFO transfer,
+ * __stop_tx_rs485 must be called only when both FIFO and shift register
+ * are empty. It is for device driver to enable interrupt on TEMT.
+ */
+ if (!((lsr & UART_LSR_TEMT) && (lsr & UART_LSR_THRE)))
+ return;
+ }
+ __do_stop_tx(p);
+ __stop_tx_rs485(p);
+}
+
static void serial8250_stop_tx(struct uart_port *port)
{
struct uart_8250_port *up = up_to_u8250p(port);
@@ -1319,12 +1450,10 @@ static void serial8250_stop_tx(struct uart_port *port)
serial8250_rpm_put(up);
}
-static void serial8250_start_tx(struct uart_port *port)
+static inline void __start_tx(struct uart_port *port)
{
struct uart_8250_port *up = up_to_u8250p(port);
- serial8250_rpm_get_tx(up);
-
if (up->dma && !up->dma->tx_dma(up))
return;
@@ -1350,6 +1479,30 @@ static void serial8250_start_tx(struct uart_port *port)
}
}
+static void serial8250_em485_handle_start_tx(unsigned long arg)
+{
+ struct uart_8250_port *p = (struct uart_8250_port *)arg;
+
+ __start_tx(&p->port);
+}
+
+static void serial8250_start_tx(struct uart_port *port)
+{
+ struct uart_8250_port *up = up_to_u8250p(port);
+ __u32 delay;
+
+ serial8250_rpm_get_tx(up);
+
+ if (up->rs485_emul && timer_pending(&up->rs485_emul->start_tx_timer))
+ return;
+
+ if (up->rs485_emul && (delay = __start_tx_rs485(up))) {
+ mod_timer(&up->rs485_emul->start_tx_timer, jiffies + delay * HZ / 1000);
+ } else {
+ __start_tx(port);
+ }
+}
+
static void serial8250_throttle(struct uart_port *port)
{
port->throttle(port);
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index faa0e03..99e59fc 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -76,6 +76,11 @@ struct uart_8250_ops {
void (*release_irq)(struct uart_8250_port *);
};
+struct uart_8250_rs485_emul {
+ struct timer_list start_tx_timer; /* "rs485 start tx" timer */
+ struct timer_list stop_tx_timer; /* "rs485 stop tx" timer */
+};
+
/*
* This should be used by drivers which want to register
* their own 8250 ports without registering their own
@@ -122,6 +127,8 @@ struct uart_8250_port {
/* 8250 specific callbacks */
int (*dl_read)(struct uart_8250_port *);
void (*dl_write)(struct uart_8250_port *, int);
+
+ struct uart_8250_rs485_emul *rs485_emul;
};
static inline struct uart_8250_port *up_to_u8250p(struct uart_port *up)
--
2.6.3
Use software emulated RS485 direction control to provide RS485 API existed in
omap_serial driver. Note that 8250_omap issues interrupt on shift register
empty which is single prerequesite for using software emulated RS485.
Signed-off-by: Matwey V. Kornilov <[email protected]>
---
drivers/tty/serial/8250/8250_omap.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index 826c5c4..323c0a4 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -698,6 +698,23 @@ static void omap_8250_throttle(struct uart_port *port)
pm_runtime_put_autosuspend(port->dev);
}
+static int omap_8250_rs485_config(struct uart_port *port, struct serial_rs485 *rs485)
+{
+ struct uart_8250_port *up = up_to_u8250p(port);
+
+ if (rs485->flags & SER_RS485_ENABLED && !serial8250_em485_enabled(up)) {
+ port->rs485 = *rs485;
+ return serial8250_em485_init(up);
+ }
+
+ if (serial8250_em485_enabled(up) && !(rs485->flags & SER_RS485_ENABLED))
+ serial8250_em485_destroy(up);
+
+ port->rs485 = *rs485;
+
+ return 0;
+}
+
static void omap_8250_unthrottle(struct uart_port *port)
{
unsigned long flags;
@@ -1144,6 +1161,7 @@ static int omap8250_probe(struct platform_device *pdev)
up.port.shutdown = omap_8250_shutdown;
up.port.throttle = omap_8250_throttle;
up.port.unthrottle = omap_8250_unthrottle;
+ up.port.rs485_config = omap_8250_rs485_config;
if (pdev->dev.of_node) {
const struct of_device_id *id;
--
2.6.3
On Sat, Dec 12, 2015 at 1:23 PM, Matwey V. Kornilov <[email protected]> wrote:
> Implementation of software emulation of RS485 direction handling is based
> on omap_serial driver.
> Before and after transmission RTS is set to the appropriate value.
>
> Note that before calling serial8250_em485_init the caller has to
> ensure that UART will interrupt when shift register empty. Otherwise,
> emultaion cannot be used.
>
> Both serial8250_em485_init and serial8250_em485_destroy are
> idempotent functions.
Just nitpick suggesting to rename both struct and field:
struct uart_8250_rs485em *rs485em;
(might be 'sw' suffix as well, which I like more — rs485sw)
and corresponding local variables if any.
>
> Signed-off-by: Matwey V. Kornilov <[email protected]>
> ---
> drivers/tty/serial/8250/8250.h | 6 ++
> drivers/tty/serial/8250/8250_port.c | 161 +++++++++++++++++++++++++++++++++++-
> include/linux/serial_8250.h | 7 ++
> 3 files changed, 170 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
> index d54dcd8..a3816c6 100644
> --- a/drivers/tty/serial/8250/8250.h
> +++ b/drivers/tty/serial/8250/8250.h
> @@ -117,6 +117,12 @@ static inline void serial_dl_write(struct uart_8250_port *up, int value)
> struct uart_8250_port *serial8250_get_port(int line);
> void serial8250_rpm_get(struct uart_8250_port *p);
> void serial8250_rpm_put(struct uart_8250_port *p);
> +int serial8250_em485_init(struct uart_8250_port *p);
> +void serial8250_em485_destroy(struct uart_8250_port *p);
> +static inline bool serial8250_em485_enabled(struct uart_8250_port *p)
> +{
> + return p->rs485_emul && (p->port.rs485.flags & SER_RS485_ENABLED);
> +}
>
> #if defined(__alpha__) && !defined(CONFIG_PCI)
> /*
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index 8ad0b2d..394d0d2 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -37,6 +37,7 @@
> #include <linux/slab.h>
> #include <linux/uaccess.h>
> #include <linux/pm_runtime.h>
> +#include <linux/timer.h>
>
> #include <asm/io.h>
> #include <asm/irq.h>
> @@ -504,6 +505,31 @@ static void serial8250_clear_fifos(struct uart_8250_port *p)
> }
> }
>
> +static inline void serial8250_em485_rts_on_send(struct uart_8250_port *p)
> +{
> + unsigned char mcr = serial_in(p, UART_MCR);
> +
> + if (p->port.rs485.flags & SER_RS485_RTS_ON_SEND)
> + mcr |= UART_MCR_RTS;
> + else
> + mcr &= ~UART_MCR_RTS;
> + serial_out(p, UART_MCR, mcr);
> +}
> +
> +static inline void serial8250_em485_rts_after_send(struct uart_8250_port *p)
> +{
> + unsigned char mcr = serial_in(p, UART_MCR);
> +
> + if (p->port.rs485.flags & SER_RS485_RTS_AFTER_SEND)
> + mcr |= UART_MCR_RTS;
> + else
> + mcr &= ~UART_MCR_RTS;
> + serial_out(p, UART_MCR, mcr);
> +}
> +
> +static void serial8250_em485_handle_start_tx(unsigned long arg);
> +static void serial8250_em485_handle_stop_tx(unsigned long arg);
> +
> void serial8250_clear_and_reinit_fifos(struct uart_8250_port *p)
> {
> serial8250_clear_fifos(p);
> @@ -528,6 +554,42 @@ void serial8250_rpm_put(struct uart_8250_port *p)
> }
> EXPORT_SYMBOL_GPL(serial8250_rpm_put);
>
> +int serial8250_em485_init(struct uart_8250_port *p)
> +{
> + if (p->rs485_emul != NULL)
> + return 0;
> +
> + p->rs485_emul = kmalloc(sizeof(struct uart_8250_rs485_emul), GFP_KERNEL);
> + if (p->rs485_emul == NULL)
> + return -ENOMEM;
> +
> + init_timer(&p->rs485_emul->stop_tx_timer);
> + p->rs485_emul->stop_tx_timer.function = serial8250_em485_handle_stop_tx;
> + p->rs485_emul->stop_tx_timer.data = (unsigned long)p;
> + p->rs485_emul->stop_tx_timer.flags |= TIMER_IRQSAFE;
> + init_timer(&p->rs485_emul->start_tx_timer);
> + p->rs485_emul->start_tx_timer.function = serial8250_em485_handle_start_tx;
> + p->rs485_emul->start_tx_timer.data = (unsigned long)p;
> + p->rs485_emul->start_tx_timer.flags |= TIMER_IRQSAFE;
> +
> + serial8250_em485_rts_after_send(p);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(serial8250_em485_init);
> +void serial8250_em485_destroy(struct uart_8250_port *p)
> +{
> + if (p->rs485_emul == NULL)
> + return;
> +
> + del_timer_sync(&p->rs485_emul->start_tx_timer);
> + del_timer_sync(&p->rs485_emul->stop_tx_timer);
> +
> + kfree(p->rs485_emul);
> + p->rs485_emul = NULL;
> +}
> +EXPORT_SYMBOL_GPL(serial8250_em485_destroy);
> +
> /*
> * These two wrappers ensure that enable_runtime_pm_tx() can be called more than
> * once and disable_runtime_pm_tx() will still disable RPM because the fifo is
> @@ -1293,7 +1355,61 @@ static void serial8250_stop_rx(struct uart_port *port)
> serial8250_rpm_put(up);
> }
>
> -static inline void __stop_tx(struct uart_8250_port *p)
> +static __u32 __start_tx_rs485(struct uart_8250_port *p)
> +{
> + if (!serial8250_em485_enabled(p))
> + return 0;
> +
> + if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX))
> + serial8250_stop_rx(&p->port);
> +
> + del_timer_sync(&p->rs485_emul->stop_tx_timer);
> +
> + if (!!(p->port.rs485.flags & SER_RS485_RTS_ON_SEND) != !!(serial_in(p, UART_MCR) & UART_MCR_RTS)) {
> + serial8250_em485_rts_on_send(p);
> + return p->port.rs485.delay_rts_before_send;
> + }
> +
> + return 0;
> +}
> +
> +static inline void __do_stop_tx_rs485(struct uart_8250_port *p)
> +{
> + if (!serial8250_em485_enabled(p))
> + return;
> +
> + serial8250_em485_rts_after_send(p);
> + /*
> + * Empty the RX FIFO, we are not interested in anything
> + * received during the half-duplex transmission.
> + */
> + if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX))
> + serial8250_clear_fifos(p);
> +}
> +
> +static void serial8250_em485_handle_stop_tx(unsigned long arg)
> +{
> + struct uart_8250_port *p = (struct uart_8250_port *)arg;
> +
> + __do_stop_tx_rs485(p);
> +}
> +
> +static inline void __stop_tx_rs485(struct uart_8250_port *p)
> +{
> + if (!serial8250_em485_enabled(p))
> + return;
> +
> + del_timer_sync(&p->rs485_emul->start_tx_timer);
> +
> + /* __do_stop_tx_rs485 is going to set RTS according to config AND flush RX FIFO if required */
> + if (p->port.rs485.delay_rts_after_send > 0) {
> + mod_timer(&p->rs485_emul->stop_tx_timer, jiffies + p->port.rs485.delay_rts_after_send * HZ / 1000);
> + } else {
> + __do_stop_tx_rs485(p);
> + }
> +}
> +
> +static inline void __do_stop_tx(struct uart_8250_port *p)
> {
> if (p->ier & UART_IER_THRI) {
> p->ier &= ~UART_IER_THRI;
> @@ -1302,6 +1418,21 @@ static inline void __stop_tx(struct uart_8250_port *p)
> }
> }
>
> +static inline void __stop_tx(struct uart_8250_port *p)
> +{
> + if (serial8250_em485_enabled(p)) {
> + unsigned char lsr = serial_in(p, UART_LSR);
> + /* To provide required timeing and allow FIFO transfer,
> + * __stop_tx_rs485 must be called only when both FIFO and shift register
> + * are empty. It is for device driver to enable interrupt on TEMT.
> + */
> + if (!((lsr & UART_LSR_TEMT) && (lsr & UART_LSR_THRE)))
> + return;
> + }
> + __do_stop_tx(p);
> + __stop_tx_rs485(p);
> +}
> +
> static void serial8250_stop_tx(struct uart_port *port)
> {
> struct uart_8250_port *up = up_to_u8250p(port);
> @@ -1319,12 +1450,10 @@ static void serial8250_stop_tx(struct uart_port *port)
> serial8250_rpm_put(up);
> }
>
> -static void serial8250_start_tx(struct uart_port *port)
> +static inline void __start_tx(struct uart_port *port)
> {
> struct uart_8250_port *up = up_to_u8250p(port);
>
> - serial8250_rpm_get_tx(up);
> -
> if (up->dma && !up->dma->tx_dma(up))
> return;
>
> @@ -1350,6 +1479,30 @@ static void serial8250_start_tx(struct uart_port *port)
> }
> }
>
> +static void serial8250_em485_handle_start_tx(unsigned long arg)
> +{
> + struct uart_8250_port *p = (struct uart_8250_port *)arg;
> +
> + __start_tx(&p->port);
> +}
> +
> +static void serial8250_start_tx(struct uart_port *port)
> +{
> + struct uart_8250_port *up = up_to_u8250p(port);
> + __u32 delay;
> +
> + serial8250_rpm_get_tx(up);
> +
> + if (up->rs485_emul && timer_pending(&up->rs485_emul->start_tx_timer))
> + return;
> +
> + if (up->rs485_emul && (delay = __start_tx_rs485(up))) {
> + mod_timer(&up->rs485_emul->start_tx_timer, jiffies + delay * HZ / 1000);
> + } else {
> + __start_tx(port);
> + }
> +}
> +
> static void serial8250_throttle(struct uart_port *port)
> {
> port->throttle(port);
> diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
> index faa0e03..99e59fc 100644
> --- a/include/linux/serial_8250.h
> +++ b/include/linux/serial_8250.h
> @@ -76,6 +76,11 @@ struct uart_8250_ops {
> void (*release_irq)(struct uart_8250_port *);
> };
>
> +struct uart_8250_rs485_emul {
> + struct timer_list start_tx_timer; /* "rs485 start tx" timer */
> + struct timer_list stop_tx_timer; /* "rs485 stop tx" timer */
> +};
> +
> /*
> * This should be used by drivers which want to register
> * their own 8250 ports without registering their own
> @@ -122,6 +127,8 @@ struct uart_8250_port {
> /* 8250 specific callbacks */
> int (*dl_read)(struct uart_8250_port *);
> void (*dl_write)(struct uart_8250_port *, int);
> +
> + struct uart_8250_rs485_emul *rs485_emul;
> };
>
> static inline struct uart_8250_port *up_to_u8250p(struct uart_port *up)
> --
> 2.6.3
>
--
With Best Regards,
Andy Shevchenko
2015-12-20 19:41 GMT+03:00 Andy Shevchenko <[email protected]>:
> On Sat, Dec 12, 2015 at 1:23 PM, Matwey V. Kornilov <[email protected]> wrote:
>> Implementation of software emulation of RS485 direction handling is based
>> on omap_serial driver.
>> Before and after transmission RTS is set to the appropriate value.
>>
>> Note that before calling serial8250_em485_init the caller has to
>> ensure that UART will interrupt when shift register empty. Otherwise,
>> emultaion cannot be used.
>>
>> Both serial8250_em485_init and serial8250_em485_destroy are
>> idempotent functions.
>
> Just nitpick suggesting to rename both struct and field:
>
> struct uart_8250_rs485em *rs485em;
Why not
struct uart_8250_em485 *em485;
to be consistent with function name suffix?
>
> (might be 'sw' suffix as well, which I like more — rs485sw)
>
> and corresponding local variables if any.
>
>>
>> Signed-off-by: Matwey V. Kornilov <[email protected]>
>> ---
>> drivers/tty/serial/8250/8250.h | 6 ++
>> drivers/tty/serial/8250/8250_port.c | 161 +++++++++++++++++++++++++++++++++++-
>> include/linux/serial_8250.h | 7 ++
>> 3 files changed, 170 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
>> index d54dcd8..a3816c6 100644
>> --- a/drivers/tty/serial/8250/8250.h
>> +++ b/drivers/tty/serial/8250/8250.h
>> @@ -117,6 +117,12 @@ static inline void serial_dl_write(struct uart_8250_port *up, int value)
>> struct uart_8250_port *serial8250_get_port(int line);
>> void serial8250_rpm_get(struct uart_8250_port *p);
>> void serial8250_rpm_put(struct uart_8250_port *p);
>> +int serial8250_em485_init(struct uart_8250_port *p);
>> +void serial8250_em485_destroy(struct uart_8250_port *p);
>> +static inline bool serial8250_em485_enabled(struct uart_8250_port *p)
>> +{
>> + return p->rs485_emul && (p->port.rs485.flags & SER_RS485_ENABLED);
>> +}
>>
>> #if defined(__alpha__) && !defined(CONFIG_PCI)
>> /*
>> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
>> index 8ad0b2d..394d0d2 100644
>> --- a/drivers/tty/serial/8250/8250_port.c
>> +++ b/drivers/tty/serial/8250/8250_port.c
>> @@ -37,6 +37,7 @@
>> #include <linux/slab.h>
>> #include <linux/uaccess.h>
>> #include <linux/pm_runtime.h>
>> +#include <linux/timer.h>
>>
>> #include <asm/io.h>
>> #include <asm/irq.h>
>> @@ -504,6 +505,31 @@ static void serial8250_clear_fifos(struct uart_8250_port *p)
>> }
>> }
>>
>> +static inline void serial8250_em485_rts_on_send(struct uart_8250_port *p)
>> +{
>> + unsigned char mcr = serial_in(p, UART_MCR);
>> +
>> + if (p->port.rs485.flags & SER_RS485_RTS_ON_SEND)
>> + mcr |= UART_MCR_RTS;
>> + else
>> + mcr &= ~UART_MCR_RTS;
>> + serial_out(p, UART_MCR, mcr);
>> +}
>> +
>> +static inline void serial8250_em485_rts_after_send(struct uart_8250_port *p)
>> +{
>> + unsigned char mcr = serial_in(p, UART_MCR);
>> +
>> + if (p->port.rs485.flags & SER_RS485_RTS_AFTER_SEND)
>> + mcr |= UART_MCR_RTS;
>> + else
>> + mcr &= ~UART_MCR_RTS;
>> + serial_out(p, UART_MCR, mcr);
>> +}
>> +
>> +static void serial8250_em485_handle_start_tx(unsigned long arg);
>> +static void serial8250_em485_handle_stop_tx(unsigned long arg);
>> +
>> void serial8250_clear_and_reinit_fifos(struct uart_8250_port *p)
>> {
>> serial8250_clear_fifos(p);
>> @@ -528,6 +554,42 @@ void serial8250_rpm_put(struct uart_8250_port *p)
>> }
>> EXPORT_SYMBOL_GPL(serial8250_rpm_put);
>>
>> +int serial8250_em485_init(struct uart_8250_port *p)
>> +{
>> + if (p->rs485_emul != NULL)
>> + return 0;
>> +
>> + p->rs485_emul = kmalloc(sizeof(struct uart_8250_rs485_emul), GFP_KERNEL);
>> + if (p->rs485_emul == NULL)
>> + return -ENOMEM;
>> +
>> + init_timer(&p->rs485_emul->stop_tx_timer);
>> + p->rs485_emul->stop_tx_timer.function = serial8250_em485_handle_stop_tx;
>> + p->rs485_emul->stop_tx_timer.data = (unsigned long)p;
>> + p->rs485_emul->stop_tx_timer.flags |= TIMER_IRQSAFE;
>> + init_timer(&p->rs485_emul->start_tx_timer);
>> + p->rs485_emul->start_tx_timer.function = serial8250_em485_handle_start_tx;
>> + p->rs485_emul->start_tx_timer.data = (unsigned long)p;
>> + p->rs485_emul->start_tx_timer.flags |= TIMER_IRQSAFE;
>> +
>> + serial8250_em485_rts_after_send(p);
>> +
>> + return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(serial8250_em485_init);
>> +void serial8250_em485_destroy(struct uart_8250_port *p)
>> +{
>> + if (p->rs485_emul == NULL)
>> + return;
>> +
>> + del_timer_sync(&p->rs485_emul->start_tx_timer);
>> + del_timer_sync(&p->rs485_emul->stop_tx_timer);
>> +
>> + kfree(p->rs485_emul);
>> + p->rs485_emul = NULL;
>> +}
>> +EXPORT_SYMBOL_GPL(serial8250_em485_destroy);
>> +
>> /*
>> * These two wrappers ensure that enable_runtime_pm_tx() can be called more than
>> * once and disable_runtime_pm_tx() will still disable RPM because the fifo is
>> @@ -1293,7 +1355,61 @@ static void serial8250_stop_rx(struct uart_port *port)
>> serial8250_rpm_put(up);
>> }
>>
>> -static inline void __stop_tx(struct uart_8250_port *p)
>> +static __u32 __start_tx_rs485(struct uart_8250_port *p)
>> +{
>> + if (!serial8250_em485_enabled(p))
>> + return 0;
>> +
>> + if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX))
>> + serial8250_stop_rx(&p->port);
>> +
>> + del_timer_sync(&p->rs485_emul->stop_tx_timer);
>> +
>> + if (!!(p->port.rs485.flags & SER_RS485_RTS_ON_SEND) != !!(serial_in(p, UART_MCR) & UART_MCR_RTS)) {
>> + serial8250_em485_rts_on_send(p);
>> + return p->port.rs485.delay_rts_before_send;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static inline void __do_stop_tx_rs485(struct uart_8250_port *p)
>> +{
>> + if (!serial8250_em485_enabled(p))
>> + return;
>> +
>> + serial8250_em485_rts_after_send(p);
>> + /*
>> + * Empty the RX FIFO, we are not interested in anything
>> + * received during the half-duplex transmission.
>> + */
>> + if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX))
>> + serial8250_clear_fifos(p);
>> +}
>> +
>> +static void serial8250_em485_handle_stop_tx(unsigned long arg)
>> +{
>> + struct uart_8250_port *p = (struct uart_8250_port *)arg;
>> +
>> + __do_stop_tx_rs485(p);
>> +}
>> +
>> +static inline void __stop_tx_rs485(struct uart_8250_port *p)
>> +{
>> + if (!serial8250_em485_enabled(p))
>> + return;
>> +
>> + del_timer_sync(&p->rs485_emul->start_tx_timer);
>> +
>> + /* __do_stop_tx_rs485 is going to set RTS according to config AND flush RX FIFO if required */
>> + if (p->port.rs485.delay_rts_after_send > 0) {
>> + mod_timer(&p->rs485_emul->stop_tx_timer, jiffies + p->port.rs485.delay_rts_after_send * HZ / 1000);
>> + } else {
>> + __do_stop_tx_rs485(p);
>> + }
>> +}
>> +
>> +static inline void __do_stop_tx(struct uart_8250_port *p)
>> {
>> if (p->ier & UART_IER_THRI) {
>> p->ier &= ~UART_IER_THRI;
>> @@ -1302,6 +1418,21 @@ static inline void __stop_tx(struct uart_8250_port *p)
>> }
>> }
>>
>> +static inline void __stop_tx(struct uart_8250_port *p)
>> +{
>> + if (serial8250_em485_enabled(p)) {
>> + unsigned char lsr = serial_in(p, UART_LSR);
>> + /* To provide required timeing and allow FIFO transfer,
>> + * __stop_tx_rs485 must be called only when both FIFO and shift register
>> + * are empty. It is for device driver to enable interrupt on TEMT.
>> + */
>> + if (!((lsr & UART_LSR_TEMT) && (lsr & UART_LSR_THRE)))
>> + return;
>> + }
>> + __do_stop_tx(p);
>> + __stop_tx_rs485(p);
>> +}
>> +
>> static void serial8250_stop_tx(struct uart_port *port)
>> {
>> struct uart_8250_port *up = up_to_u8250p(port);
>> @@ -1319,12 +1450,10 @@ static void serial8250_stop_tx(struct uart_port *port)
>> serial8250_rpm_put(up);
>> }
>>
>> -static void serial8250_start_tx(struct uart_port *port)
>> +static inline void __start_tx(struct uart_port *port)
>> {
>> struct uart_8250_port *up = up_to_u8250p(port);
>>
>> - serial8250_rpm_get_tx(up);
>> -
>> if (up->dma && !up->dma->tx_dma(up))
>> return;
>>
>> @@ -1350,6 +1479,30 @@ static void serial8250_start_tx(struct uart_port *port)
>> }
>> }
>>
>> +static void serial8250_em485_handle_start_tx(unsigned long arg)
>> +{
>> + struct uart_8250_port *p = (struct uart_8250_port *)arg;
>> +
>> + __start_tx(&p->port);
>> +}
>> +
>> +static void serial8250_start_tx(struct uart_port *port)
>> +{
>> + struct uart_8250_port *up = up_to_u8250p(port);
>> + __u32 delay;
>> +
>> + serial8250_rpm_get_tx(up);
>> +
>> + if (up->rs485_emul && timer_pending(&up->rs485_emul->start_tx_timer))
>> + return;
>> +
>> + if (up->rs485_emul && (delay = __start_tx_rs485(up))) {
>> + mod_timer(&up->rs485_emul->start_tx_timer, jiffies + delay * HZ / 1000);
>> + } else {
>> + __start_tx(port);
>> + }
>> +}
>> +
>> static void serial8250_throttle(struct uart_port *port)
>> {
>> port->throttle(port);
>> diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
>> index faa0e03..99e59fc 100644
>> --- a/include/linux/serial_8250.h
>> +++ b/include/linux/serial_8250.h
>> @@ -76,6 +76,11 @@ struct uart_8250_ops {
>> void (*release_irq)(struct uart_8250_port *);
>> };
>>
>> +struct uart_8250_rs485_emul {
>> + struct timer_list start_tx_timer; /* "rs485 start tx" timer */
>> + struct timer_list stop_tx_timer; /* "rs485 stop tx" timer */
>> +};
>> +
>> /*
>> * This should be used by drivers which want to register
>> * their own 8250 ports without registering their own
>> @@ -122,6 +127,8 @@ struct uart_8250_port {
>> /* 8250 specific callbacks */
>> int (*dl_read)(struct uart_8250_port *);
>> void (*dl_write)(struct uart_8250_port *, int);
>> +
>> + struct uart_8250_rs485_emul *rs485_emul;
>> };
>>
>> static inline struct uart_8250_port *up_to_u8250p(struct uart_port *up)
>> --
>> 2.6.3
>>
>
>
>
> --
> With Best Regards,
> Andy Shevchenko
>
--
With best regards,
Matwey V. Kornilov.
Sternberg Astronomical Institute, Lomonosov Moscow State University, Russia
119991, Moscow, Universitetsky pr-k 13, +7 (495) 9392382
On Sun, Dec 20, 2015 at 8:11 PM, Matwey V. Kornilov <[email protected]> wrote:
> 2015-12-20 19:41 GMT+03:00 Andy Shevchenko <[email protected]>:
>> On Sat, Dec 12, 2015 at 1:23 PM, Matwey V. Kornilov <[email protected]> wrote:
>>> Implementation of software emulation of RS485 direction handling is based
>>> on omap_serial driver.
>>> Before and after transmission RTS is set to the appropriate value.
>>>
>>> Note that before calling serial8250_em485_init the caller has to
>>> ensure that UART will interrupt when shift register empty. Otherwise,
>>> emultaion cannot be used.
>>>
>>> Both serial8250_em485_init and serial8250_em485_destroy are
>>> idempotent functions.
>>
>> Just nitpick suggesting to rename both struct and field:
>>
>> struct uart_8250_rs485em *rs485em;
>
> Why not
>
> struct uart_8250_em485 *em485;
>
> to be consistent with function name suffix?
I'm fine with that as well.
--
With Best Regards,
Andy Shevchenko