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Message-ID: <92aed0d9-791f-4708-8a73-4c78457a710e@kernel.org>
Date:   Mon, 2 Oct 2023 09:19:26 +0200
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Subject: Re: [PATCH 4/4] tty: serial: 8250: Add support for MOXA PCIe boards
 to switch interface between RS422/RS485
Content-Language: en-US
To:     Crescent CY Hsieh <crescentcy.hsieh@moxa.com>,
        gregkh@linuxfoundation.org
Cc:     linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org
References: <20231002015702.30509-1-crescentcy.hsieh@moxa.com>
 <20231002015702.30509-5-crescentcy.hsieh@moxa.com>
From:   Jiri Slaby <jirislaby@kernel.org>
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In-Reply-To: <20231002015702.30509-5-crescentcy.hsieh@moxa.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
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Precedence: bulk

On 02. 10. 23, 3:57, Crescent CY Hsieh wrote:
> MOXA PCIe boards have 4 serial interfaces and don't require additional
> stuff to switch between interfaces:
> 
> - RS232
> - RS422
> - RS485_2W (half-duplex)
> - RS485_4W (full-duplex)
> 
> By using ioctl command "TIOCRS485", it can switch between default
> interface and RS485 if supported.
> 
> That means, for RS422/RS485 board, it can switch between RS422 and
> RS485 by setting the flags within struct serial_rs485.
> 
> However, for the RS232/RS422/RS485 board, it can only switch between
> RS232 and RS485, there's no flag for switching interface into RS422.
> 
> This patch adds a flag call "SER_RS422_ENALBED" in serial.h and modifies

Hopefully not SER_RS422_ENALBED.

> serial_core.c to make it possible to switch interface between RS232,
> RS422 and RS485.
> 
> Signed-off-by: Crescent CY Hsieh <crescentcy.hsieh@moxa.com>
> ---
>   drivers/tty/serial/8250/8250_pci.c | 41 ++++++++++++++++++++++++++++++
>   drivers/tty/serial/serial_core.c   | 20 ++++++++++++---
>   include/uapi/linux/serial.h        |  4 +++
>   3 files changed, 61 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
> index 31bfe5381000..86dce37f08c0 100644
> --- a/drivers/tty/serial/8250/8250_pci.c
> +++ b/drivers/tty/serial/8250/8250_pci.c
> @@ -1898,6 +1898,10 @@ pci_sunix_setup(struct serial_private *priv,
>   
>   #define MOXA_GPIO_SET_ALL_OUTPUT	0x0F
>   
> +static const struct serial_rs485 pci_moxa_rs485_supported = {
> +	.flags = SER_RS485_ENABLED | SER_RS485_RX_DURING_TX | SER_RS422_ENABLED,
> +};
> +
>   static int pci_moxa_set_interface(struct pci_dev *dev,
>   				  unsigned int port_idx,
>   				  unsigned char mode)
> @@ -1921,6 +1925,30 @@ static int pci_moxa_set_interface(struct pci_dev *dev,
>   	return 0;
>   }
>   
> +static int pci_moxa_rs485_config(struct uart_port *port,
> +				 struct ktermios *termios,
> +				 struct serial_rs485 *rs485)
> +{
> +	struct pci_dev *dev = to_pci_dev(port->dev);
> +	unsigned short device = dev->device;
> +	unsigned char mode = MOXA_RS232;

u8

> +
> +	if (rs485->flags & SER_RS485_ENABLED) {
> +		if (rs485->flags & SER_RS485_RX_DURING_TX)
> +			mode = MOXA_RS485_4W;
> +		else
> +			mode = MOXA_RS485_2W;
> +	} else if (rs485->flags & SER_RS422_ENABLED) {
> +		mode = MOXA_RS422;
> +	} else {
> +		if ((device & 0x0F00) == 0x0300) {

This is the second time you test this. Introduce a function.

> +			pci_warn(dev, "RS232 interface is not supported.");

Don't spam the logs.

> +			return -EINVAL;
> +		}
> +	}

add \n here

> +	return pci_moxa_set_interface(dev, port->line, mode);
> +}
> +
>   static int pci_moxa_init(struct pci_dev *dev)
>   {
>   	unsigned short device = dev->device;
> @@ -1965,9 +1993,22 @@ static int pci_moxa_setup(struct serial_private *priv,
>   			  struct uart_8250_port *port,
>   			  int idx)
>   {
> +	struct pci_dev *dev = priv->dev;
> +	unsigned short device = dev->device;
>   	unsigned int bar = FL_GET_BASE(board->flags);
>   	int offset;
>   
> +	/*
> +	 * For the device IDs of MOXA PCIe boards match the pattern 0x*3** and 0x*1**,
> +	 * these boards support switching interface between RS422/RS485 using TIOCSRS485.
> +	 */
> +	if ((device & 0x0F00) == 0x0100 || (device & 0x0F00) == 0x0300) {

Use helpers.

> +		port->port.rs485_config = pci_moxa_rs485_config;
> +		port->port.rs485_supported = pci_moxa_rs485_supported;
> +
> +		if ((device & 0x0F00) == 0x0300)
> +			port->port.rs485.flags = SER_RE422_ENABLED;
> +	}
>   	if (board->num_ports == 4 && idx == 3)
>   		offset = 7 * board->uart_offset;
>   	else
> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> index 7bdc21d5e13b..f316d9705809 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -1299,7 +1299,7 @@ static int uart_get_icount(struct tty_struct *tty,
>   
>   #define SER_RS485_LEGACY_FLAGS	(SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | \
>   				 SER_RS485_RTS_AFTER_SEND | SER_RS485_RX_DURING_TX | \
> -				 SER_RS485_TERMINATE_BUS)
> +				 SER_RS485_TERMINATE_BUS | SER_RS422_ENALBED)

So have you tested this at all?

> @@ -1365,11 +1365,23 @@ static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs4
>   {
>   	u32 supported_flags = port->rs485_supported.flags;
>   
> -	if (!(rs485->flags & SER_RS485_ENABLED)) {
> +	if (!(rs485->flags & SER_RS485_ENABLED) && !(rs485->flags & SER_RS422_ENABLED)) {
>   		memset(rs485, 0, sizeof(*rs485));
>   		return;
>   	}
> -
> +	/* Pick sane setting if the user enables both interfaces */
> +	if (rs485->flags & SER_RS485_ENABLED && rs485->flags & SER_RS422_ENABLED) {
> +		dev_warn_ratelimited(port->dev,
> +			"%s (%d): Invalid serial interface setting, using RS485 instead\n",
> +			port->name, port->line);
> +		rs485->flags &= ~(SER_RS422_ENABLED);

No need for parens.

> +	}
> +	/* Clear other bits and return if enalbe RS422 */

enable

> +	if (rs485->flags & SER_RS422_ENABLED) {
> +		memset(rs485, 0, sizeof(*rs485));
> +		rs485->flags |= SER_RS422_ENABLED;
> +		return;
> +	}
>   	/* Pick sane settings if the user hasn't */
>   	if ((supported_flags & (SER_RS485_RTS_ON_SEND|SER_RS485_RTS_AFTER_SEND)) &&
>   	    !(rs485->flags & SER_RS485_RTS_ON_SEND) ==
> @@ -1394,7 +1406,7 @@ static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs4
>   static void uart_set_rs485_termination(struct uart_port *port,
>   				       const struct serial_rs485 *rs485)
>   {
> -	if (!(rs485->flags & SER_RS485_ENABLED))
> +	if (!(rs485->flags & SER_RS485_ENABLED) && !(rs485->flags & SER_RS422_ENABLED))
>   		return;
>   
>   	gpiod_set_value_cansleep(port->rs485_term_gpio,
> diff --git a/include/uapi/linux/serial.h b/include/uapi/linux/serial.h
> index 53bc1af67a41..427609fd52cb 100644
> --- a/include/uapi/linux/serial.h
> +++ b/include/uapi/linux/serial.h
> @@ -137,6 +137,8 @@ struct serial_icounter_struct {
>    * * %SER_RS485_ADDRB		- Enable RS485 addressing mode.
>    * * %SER_RS485_ADDR_RECV - Receive address filter (enables @addr_recv). Requires %SER_RS485_ADDRB.
>    * * %SER_RS485_ADDR_DEST - Destination address (enables @addr_dest). Requires %SER_RS485_ADDRB.
> + *
> + * * %SER_RS422_ENABLED		- RS422 enabled.
>    */
>   struct serial_rs485 {
>   	__u32	flags;
> @@ -149,6 +151,8 @@ struct serial_rs485 {
>   #define SER_RS485_ADDR_RECV		(1 << 7)
>   #define SER_RS485_ADDR_DEST		(1 << 8)
>   
> +#define SER_RS422_ENABLED		(1 << 9)
> +
>   	__u32	delay_rts_before_send;
>   	__u32	delay_rts_after_send;
>   

thanks,
-- 
js
suse labs