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Message-ID: <b1271a91-a2f6-4f06-9b3d-c8b32bd6bf2c@kunbus.com>
Date: Wed, 27 Nov 2024 13:58:06 +0100
From: Philipp Rosenberger <p.rosenberger@...bus.com>
To: Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>, linux-rtc@...r.kernel.org,
linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
Lino Sanfilippo <l.sanfilippo@...bus.com>,
Thomas Böhler <t.boehler@...bus.com>,
Hugo Villeneuve <hvilleneuve@...onoff.com>
Subject: Re: [PATCH v3 0/2] rtc: pcf2127: make battery switch-over
configurable
Hi,
On 14.11.24 09:51, Alexandre Belloni wrote:
> Hello,
>
> This has been discussed multiple times in the past, we can't have a DT
> property for this as we need to be able to change it at runtime. There
> is already a userspace interface to do this.
>
> Below is my current patch for this that has been tested on pcf2127. I
> didn't send it yet because we are losing information when switching from
> standard or direct mode to disabled because when BSM is disabled, there
> is no configuration where battery low detection function is enabled so
> going from disabled to standard or direct will keep BLD disabled.
Sorry for my late response. I've tested the patch on our hardware. and
this would solve our problem. I understand, that it is not ideal, that
information is lost when switching modes. But I can't figure a way how
to avoid this.
Thank you and best regards,
Philipp
>
> 8<--------------------------------------------------------------------
>
> From 7db70b33c3939a0ebe147c32f406b34a2f5f1be8 Mon Sep 17 00:00:00 2001
> From: Alexandre Belloni <alexandre.belloni@...tlin.com>
> Date: Sat, 24 Feb 2024 19:58:20 +0100
> Subject: [PATCH] rtc: pcf2127: add BSM support
>
> The pcf2127 encodes BSM, BLD and power fail detection in the same set of
> bits so it is necessary to do some calculation when changing BSM to keep
> the rest of the configuration as-is. However, when BSM is disabled, there
> is no configuration with BLD enabled so this will be lost when coming back
> to a mode with BSM enabled.
>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@...tlin.com>
> ---
> drivers/rtc/rtc-pcf2127.c | 81 +++++++++++++++++++++++++++++++++++++++
> 1 file changed, 81 insertions(+)
>
> diff --git a/drivers/rtc/rtc-pcf2127.c b/drivers/rtc/rtc-pcf2127.c
> index 9c04c4e1a49c..a7f73192d53d 100644
> --- a/drivers/rtc/rtc-pcf2127.c
> +++ b/drivers/rtc/rtc-pcf2127.c
> @@ -48,6 +48,7 @@
> #define PCF2127_BIT_CTRL3_BLF BIT(2)
> #define PCF2127_BIT_CTRL3_BF BIT(3)
> #define PCF2127_BIT_CTRL3_BTSE BIT(4)
> +#define PCF2127_CTRL3_PM GENMASK(7, 5)
> /* Time and date registers */
> #define PCF2127_REG_TIME_BASE 0x03
> #define PCF2127_BIT_SC_OSF BIT(7)
> @@ -331,6 +332,84 @@ static int pcf2127_rtc_set_time(struct device *dev, struct rtc_time *tm)
> return 0;
> }
>
> +static int pcf2127_param_get(struct device *dev, struct rtc_param *param)
> +{
> + struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
> + u32 value;
> + int ret;
> +
> + switch (param->param) {
> + case RTC_PARAM_BACKUP_SWITCH_MODE:
> + ret = regmap_read(pcf2127->regmap, PCF2127_REG_CTRL3, &value);
> + if (ret < 0)
> + return ret;
> +
> + value = FIELD_GET(PCF2127_CTRL3_PM, value);
> +
> + if (value < 0x3)
> + param->uvalue = RTC_BSM_LEVEL;
> + else if (value < 0x6)
> + param->uvalue = RTC_BSM_DIRECT;
> + else
> + param->uvalue = RTC_BSM_DISABLED;
> +
> + break;
> +
> + default:
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> +static int pcf2127_param_set(struct device *dev, struct rtc_param *param)
> +{
> + struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
> + u8 mode = 0;
> + u32 value;
> + int ret;
> +
> + switch (param->param) {
> + case RTC_PARAM_BACKUP_SWITCH_MODE:
> + ret = regmap_read(pcf2127->regmap, PCF2127_REG_CTRL3, &value);
> + if (ret < 0)
> + return ret;
> +
> + value = FIELD_GET(PCF2127_CTRL3_PM, value);
> +
> + if (value > 5)
> + value -= 5;
> + else if (value > 2)
> + value -= 3;
> +
> + switch (param->uvalue) {
> + case RTC_BSM_LEVEL:
> + break;
> + case RTC_BSM_DIRECT:
> + mode = 3;
> + break;
> + case RTC_BSM_DISABLED:
> + if (value == 0)
> + value = 1;
> + mode = 5;
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + return regmap_update_bits(pcf2127->regmap, PCF2127_REG_CTRL3,
> + PCF2127_CTRL3_PM,
> + FIELD_PREP(PCF2127_CTRL3_PM, mode + value));
> +
> + break;
> +
> + default:
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> static int pcf2127_rtc_ioctl(struct device *dev,
> unsigned int cmd, unsigned long arg)
> {
> @@ -741,6 +820,8 @@ static const struct rtc_class_ops pcf2127_rtc_ops = {
> .read_alarm = pcf2127_rtc_read_alarm,
> .set_alarm = pcf2127_rtc_set_alarm,
> .alarm_irq_enable = pcf2127_rtc_alarm_irq_enable,
> + .param_get = pcf2127_param_get,
> + .param_set = pcf2127_param_set,
> };
>
> /* sysfs interface */
> --
> 2.47.0
>
>
>
> --
> Alexandre Belloni, co-owner and COO, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
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