linux-kernel - Re: [PATCH v5 6/9] tty: serial: atmel: Separate mode clearing between UART and USART

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Date:   Fri, 30 Sep 2022 07:22:36 +0000
From:   <Claudiu.Beznea@...rochip.com>
To:     <Sergiu.Moga@...rochip.com>, <lee@...nel.org>,
        <robh+dt@...nel.org>, <krzysztof.kozlowski+dt@...aro.org>,
        <Nicolas.Ferre@...rochip.com>, <alexandre.belloni@...tlin.com>,
        <radu_nicolae.pirea@....ro>, <richard.genoud@...il.com>,
        <gregkh@...uxfoundation.org>, <jirislaby@...nel.org>,
        <Kavyasree.Kotagiri@...rochip.com>
CC:     <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-spi@...r.kernel.org>,
        <linux-serial@...r.kernel.org>
Subject: Re: [PATCH v5 6/9] tty: serial: atmel: Separate mode clearing between
 UART and USART

On 22.09.2022 14:33, Sergiu Moga wrote:
> When clearing the mode of the serial IP inside the atmel_set_termios()
> method, make sure that the difference between the bitfields placement
> of the UART IP's and USART IP's is taken into account, as some of
> them overlap with each other. For example, ATMEL_UA_BRSRCCK overlaps
> with ATMEL_US_NBSTOP and ATMEL_US_USCLKS overlaps with ATMEL_UA_FILTER.
> 
> Furthermore, add definitions for the Baud Rate Source Clock and the
> Filter bitfields of the Mode Register of UART IP's, since they were
> missing.
> 
> Signed-off-by: Sergiu Moga <sergiu.moga@...rochip.com>

Reviewed-by: Claudiu Beznea <claudiu.beznea@...rochip.com>


> ---
> 
> 
> v1 -> v5:
> - This patch was not here before but it also includes the previous patch:
> `[PATCH v4 7/9] tty: serial: atmel: Define BRSRCCK bitmask of UART IP's Mode Register`
> squashed into it and define BRSRCCK as a bitfield instead of a bitmask,
> since it is only 1 bit.
> 
> 
> 
>  drivers/tty/serial/atmel_serial.c | 7 +++++--
>  drivers/tty/serial/atmel_serial.h | 2 ++
>  2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
> index ab4a9dfae07d..e3e14cb7668b 100644
> --- a/drivers/tty/serial/atmel_serial.c
> +++ b/drivers/tty/serial/atmel_serial.c
> @@ -2134,8 +2134,11 @@ static void atmel_set_termios(struct uart_port *port,
>  	mode = old_mode = atmel_uart_readl(port, ATMEL_US_MR);
>  
>  	/* reset the mode, clock divisor, parity, stop bits and data size */
> -	mode &= ~(ATMEL_US_USCLKS | ATMEL_US_CHRL | ATMEL_US_NBSTOP |
> -		  ATMEL_US_PAR | ATMEL_US_USMODE);
> +	if (atmel_port->is_usart)
> +		mode &= ~(ATMEL_US_NBSTOP | ATMEL_US_PAR | ATMEL_US_CHRL |
> +			  ATMEL_US_USCLKS | ATMEL_US_USMODE);
> +	else
> +		mode &= ~(ATMEL_UA_BRSRCCK | ATMEL_US_PAR | ATMEL_UA_FILTER);
>  
>  	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
>  
> diff --git a/drivers/tty/serial/atmel_serial.h b/drivers/tty/serial/atmel_serial.h
> index 0d8a0f9cc5c3..2a525b58e11a 100644
> --- a/drivers/tty/serial/atmel_serial.h
> +++ b/drivers/tty/serial/atmel_serial.h
> @@ -50,6 +50,7 @@
>  #define		ATMEL_US_USCLKS_MCK		(0 <<  4)
>  #define		ATMEL_US_USCLKS_MCK_DIV8	(1 <<  4)
>  #define		ATMEL_US_USCLKS_SCK		(3 <<  4)
> +#define	ATMEL_UA_FILTER		BIT(4)
>  #define	ATMEL_US_CHRL		GENMASK(7, 6)	/* Character Length */
>  #define		ATMEL_US_CHRL_5			(0 <<  6)
>  #define		ATMEL_US_CHRL_6			(1 <<  6)
> @@ -67,6 +68,7 @@
>  #define		ATMEL_US_NBSTOP_1		(0 << 12)
>  #define		ATMEL_US_NBSTOP_1_5		(1 << 12)
>  #define		ATMEL_US_NBSTOP_2		(2 << 12)
> +#define	ATMEL_UA_BRSRCCK	BIT(12)	/* Clock Selection for UART */
>  #define	ATMEL_US_CHMODE		GENMASK(15, 14)	/* Channel Mode */
>  #define		ATMEL_US_CHMODE_NORMAL		(0 << 14)
>  #define		ATMEL_US_CHMODE_ECHO		(1 << 14)