linux-kernel - Re: [PATCH] rtc: add BSM flags descriptions

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Message-Id: <20260113100427.f2162f0d5ba80a259511f9d2@hugovil.com>
Date: Tue, 13 Jan 2026 10:04:27 -0500
From: Hugo Villeneuve <hugo@...ovil.com>
To: Hugo Villeneuve <hugo@...ovil.com>
Cc: Alexandre Belloni <alexandre.belloni@...tlin.com>, Hugo Villeneuve
 <hvilleneuve@...onoff.com>, linux-rtc@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rtc: add BSM flags descriptions

On Mon, 21 Jul 2025 11:33:31 -0400
Hugo Villeneuve <hugo@...ovil.com> wrote:

> From: Hugo Villeneuve <hvilleneuve@...onoff.com>
> 
> It is hard to decipher what the RTC BSM flags mean, so add
> meaningful descriptions.
> 
> Signed-off-by: Hugo Villeneuve <hvilleneuve@...onoff.com>
> ---
>  include/uapi/linux/rtc.h | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/include/uapi/linux/rtc.h b/include/uapi/linux/rtc.h
> index 97aca4503a6a..da65130e316d 100644
> --- a/include/uapi/linux/rtc.h
> +++ b/include/uapi/linux/rtc.h
> @@ -141,10 +141,15 @@ struct rtc_param {
>  #define RTC_PARAM_CORRECTION		1
>  #define RTC_PARAM_BACKUP_SWITCH_MODE	2
>  
> +/* Backup switch mode */
>  #define RTC_BSM_DISABLED	0
> -#define RTC_BSM_DIRECT		1
> -#define RTC_BSM_LEVEL		2
> -#define RTC_BSM_STANDBY		3
> +#define RTC_BSM_DIRECT		1 /* Switch if Vbackup > Vdd */
> +#define RTC_BSM_LEVEL		2 /* Switch based on a threshold, usually with an hysteresis */
> +#define RTC_BSM_STANDBY		3 /*
> +				   * Switch if Vdd > Vbackup.
> +				   * Useful to ensure the RTC doesn't draw any
> +				   * power until the device is first powered on.
> +				   */
>  
>  #define RTC_MAX_FREQ	8192

Ping?


>  
> 
> base-commit: 0bafe291cb429d39b5ff70bcf7b2f3ab026dcb02
> -- 
> 2.39.5
> 
> 


-- 
Hugo Villeneuve