Subject: Re: [PATCH v2] rtc: rs5c372: Add RTC_VL_READ, RTC_VL_CLR ioctls
To:     Camel Guo <Camel.Guo@axis.com>,
        Alessandro Zummo <a.zummo@towertech.it>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>
CC:     kernel <kernel@axis.com>,
        "linux-rtc@vger.kernel.org" <linux-rtc@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
References: <20211110141442.9603-1-camel.guo@axis.com>
From:   Camel Guo <camelg@axis.com>
Message-ID: <2686847b-8834-8307-83b0-aabc7e276c8a@axis.com>
Date:   Thu, 11 Nov 2021 09:39:44 +0100
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On 11/10/21 3:14 PM, Camel Guo wrote:
> From: Camel Guo <camelg@axis.com>
> 
> In order to make it possible to get battery voltage status, this commit
> adds RTC_VL_READ, RTC_VL_CLR ioctl commands to rtc-rs5c372.
> 
> Signed-off-by: Camel Guo <camelg@axis.com>
> ---
> 
> v2: Set RTC_VL_BACKUP_LOW if VDET is set. Do not clear PON, XSTP in
> RTC_VL_CLR ioctl
> 
>  ?drivers/rtc/rtc-rs5c372.c | 60 +++++++++++++++++++++++++++++++++++++++
>  ?1 file changed, 60 insertions(+)
> 
> diff --git a/drivers/rtc/rtc-rs5c372.c b/drivers/rtc/rtc-rs5c372.c
> index 80980414890c..4ab8718d9360 100644
> --- a/drivers/rtc/rtc-rs5c372.c
> +++ b/drivers/rtc/rtc-rs5c372.c
> @@ -485,6 +485,65 @@ static int rs5c372_rtc_proc(struct device *dev, 
> struct seq_file *seq)
>  ?#define rs5c372_rtc_proc??????? NULL
>  ?#endif
> 
> +#ifdef CONFIG_RTC_INTF_DEV
> +static int rs5c372_ioctl(struct device *dev, unsigned int cmd, unsigned 
> long arg)
> +{
> +?????? struct rs5c372? *rs5c = i2c_get_clientdata(to_i2c_client(dev));
> +?????? unsigned char?? ctrl2;
> +?????? int???????????? addr;
> +?????? unsigned int??? flags;
> +
> +?????? dev_dbg(dev, "%s: cmd=%x\n", __func__, cmd);
> +
> +?????? addr = RS5C_ADDR(RS5C_REG_CTRL2);
> +?????? ctrl2 = i2c_smbus_read_byte_data(rs5c->client, addr);
> +
> +?????? switch (cmd) {
> +?????? case RTC_VL_READ:
> +?????????????? flags = 0;
> +
> +?????????????? switch (rs5c->type) {
> +?????????????? case rtc_r2025sd:
> +?????????????? case rtc_r2221tl:
> +?????????????????????? if ((rs5c->type == rtc_r2025sd && !(ctrl2 & 
> R2x2x_CTRL2_XSTP)) ||
> +?????????????????????????????? (rs5c->type == rtc_r2221tl &&? (ctrl2 & 
> R2x2x_CTRL2_XSTP))) {
> +?????????????????????????????? flags |= RTC_VL_DATA_INVALID;
> +?????????????????????? }
> +?????????????????????? if (ctrl2 & R2x2x_CTRL2_VDET)
> +?????????????????????????????? flags |= RTC_VL_BACKUP_LOW;
> +?????????????????????? break;
> +?????????????? default:
> +?????????????????????? if (ctrl2 & RS5C_CTRL2_XSTP)
> +?????????????????????????????? flags |= RTC_VL_DATA_INVALID;
> +?????????????????????? break;
> +?????????????? }
> +
> +?????????????? return put_user(flags, (unsigned int __user *)arg);
> +?????? case RTC_VL_CLR:
> +?????????????? /* clear VDET bit */
> +?????????????? switch (rs5c->type) {
> +?????????????? case rtc_r2025sd:
> +?????????????? case rtc_r2221tl:
> +?????????????????????? ctrl2 &= ~R2x2x_CTRL2_VDET;
> +?????????????? default:
> +?????????????????????? break;
> +?????????????? }
> +
> +?????????????? if (i2c_smbus_write_byte_data(rs5c->client, addr, ctrl2) 
> < 0) {
> +?????????????????????? dev_dbg(&rs5c->client->dev, "%s: write error in 
> line %i\n",
> +?????????????????????????????????????? __func__, __LINE__);
> +?????????????????????? return -EIO;
> +?????????????? }
> +?????????????? return 0;
> +?????? default:
> +?????????????? return -ENOIOCTLCMD;
> +?????? }
> +?????? return 0;
> +}
> +#else
> +#define rs5c372_ioctl? NULL
> +#endif
> +
>  ?static const struct rtc_class_ops rs5c372_rtc_ops = {
>  ???????? .proc?????????? = rs5c372_rtc_proc,
>  ???????? .read_time????? = rs5c372_rtc_read_time,
> @@ -492,6 +551,7 @@ static const struct rtc_class_ops rs5c372_rtc_ops = {
>  ???????? .read_alarm???? = rs5c_read_alarm,
>  ???????? .set_alarm????? = rs5c_set_alarm,
>  ???????? .alarm_irq_enable = rs5c_rtc_alarm_irq_enable,
> +?????? .ioctl????????? = rs5c372_ioctl,
>  ?};
> 
>  ?#if IS_ENABLED(CONFIG_RTC_INTF_SYSFS)
> -- 
> 2.20.1
> 

PATCH v3 is uploaded with the fix of avoiding setting ctrl2 register 
when unnecessary.  Please review v3 instead.