linux-kernel - Re: [PATCH 3/4] tty: serial: 8250: Fix MOXA RS422/RS485 PCIe boards not work by default

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Date:   Mon, 2 Oct 2023 09:14:32 +0200
From:   Jiri Slaby <jirislaby@...nel.org>
To:     Crescent CY Hsieh <crescentcy.hsieh@...a.com>,
        gregkh@...uxfoundation.org
Cc:     linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org
Subject: Re: [PATCH 3/4] tty: serial: 8250: Fix MOXA RS422/RS485 PCIe boards
 not work by default

On 02. 10. 23, 3:57, Crescent CY Hsieh wrote:
> MOXA PCIe RS422/RS485 boards will not function by default because of the
> initial default serial interface of all MOXA PCIe boards is set to RS232.
> 
> This patch fixes the problem above by setting the initial default serial
> interface to RS422 for those MOXA RS422/RS485 PCIe boards.
> 
> Signed-off-by: Crescent CY Hsieh <crescentcy.hsieh@...a.com>
> ---
>   drivers/tty/serial/8250/8250_pci.c | 39 +++++++++++++++++++++++++++++-
>   1 file changed, 38 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
> index a70546ac361e..31bfe5381000 100644
> --- a/drivers/tty/serial/8250/8250_pci.c
> +++ b/drivers/tty/serial/8250/8250_pci.c
> @@ -1890,17 +1890,54 @@ pci_sunix_setup(struct serial_private *priv,
>   #define MOXA_PUART_GPIO_EN	0x09
>   #define MOXA_PUART_GPIO_OUT	0x0A
>   
> +#define MOXA_RS232	0x00
> +#define MOXA_RS422	0x01
> +#define MOXA_RS485_4W	0x0B
> +#define MOXA_RS485_2W	0x0F
> +#define MOXA_UIR_OFFSET	0x04
> +
>   #define MOXA_GPIO_SET_ALL_OUTPUT	0x0F
>   
> +static int pci_moxa_set_interface(struct pci_dev *dev,

can it be const?

> +				  unsigned int port_idx,
> +				  unsigned char mode)

u8

> +{
> +	unsigned long iobar_addr = pci_resource_start(dev, 2);

resource_size_t

> +	unsigned long UIR_addr = iobar_addr + MOXA_UIR_OFFSET + (port_idx / 2);

resource_size_t. Why the parentheses?

> +	unsigned char val, intf;

u8

> +	val = inb(UIR_addr);
> +
> +	if (port_idx % 2) {
> +		intf = mode << 4;
> +		val &= 0x0F;
> +	} else {
> +		intf = mode;
> +		val &= 0xF0;
> +	}
> +	val |= intf;

May be better:
   if (port_idx % 2) {
     val &= 0x0F;
     val |= mode << 4;
   } else {
     val &= 0xF0;
     val |= mode;
   }
(no need for intf)?


> +	outb(val, UIR_addr);
> +
> +	return 0;
> +}
> +
>   static int pci_moxa_init(struct pci_dev *dev)
>   {
>   	unsigned short device = dev->device;
>   	unsigned long iobar_addr = pci_resource_start(dev, 2);
> +	int i;

unsigned

>   	int num_ports = (device & 0x00F0) >> 4;

And this one too (in the previous patch).

>   	unsigned char val;
>   
>   	outb(MOXA_GPIO_SET_ALL_OUTPUT, iobar_addr + MOXA_PUART_GPIO_EN);
> -
> +	/*
> +	 * For the device IDs of MOXA PCIe boards match the pattern 0x*3**,
> +	 * the initial default serial interface mode should be set to RS422.
> +	 */
> +	if ((device & 0x0F00) == 0x0300) {
> +		for (i = 0; i < num_ports; ++i)
> +			pci_moxa_set_interface(dev, i, MOXA_RS422);
> +	}
>   	/*
>   	 * Enable hardware buffer to prevent break signal output when system boot up.
>   	 * This hardware buffer is only supported on Mini PCIe series.

-- 
js
suse labs