Date:   Mon, 23 Jan 2023 10:54:57 -0500
From:   Hugo Villeneuve <hugo@...ovil.com>
To:     Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc:     a.zummo@...ertech.it, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, linux-rtc@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Hugo Villeneuve <hvilleneuve@...onoff.com>
Subject: Re: [PATCH v3 02/14] rtc: pcf2127: adapt for time/date registers at
 any offset

On Fri, 20 Jan 2023 19:47:53 +0100
Alexandre Belloni <alexandre.belloni@...tlin.com> wrote:

> On 15/12/2022 10:02:03-0500, Hugo Villeneuve wrote:
> > From: Hugo Villeneuve <hvilleneuve@...onoff.com>
> > 
> > This will simplify the implementation of new variants into this driver.
> > 
> > Some variants (PCF2131) have a 100th seconds register. This register is
> > currently not supported in this driver.
> > 
> > Signed-off-by: Hugo Villeneuve <hvilleneuve@...onoff.com>
> > ---
> >  drivers/rtc/rtc-pcf2127.c | 68 ++++++++++++++++++++++-----------------
> >  1 file changed, 39 insertions(+), 29 deletions(-)
> > 
> > diff --git a/drivers/rtc/rtc-pcf2127.c b/drivers/rtc/rtc-pcf2127.c
> > index b9a5d47a439f..fb0caacaabee 100644
> > --- a/drivers/rtc/rtc-pcf2127.c
> > +++ b/drivers/rtc/rtc-pcf2127.c
> > @@ -44,14 +44,17 @@
> >  #define PCF2127_BIT_CTRL3_BF			BIT(3)
> >  #define PCF2127_BIT_CTRL3_BTSE			BIT(4)
> >  /* Time and date registers */
> > -#define PCF2127_REG_SC			0x03
> > +#define PCF2127_REG_TIME_DATE_BASE	0x03
> > +/* Time and date registers offsets (starting from base register) */
> > +#define PCF2127_OFFSET_TD_SC		0
> > +#define PCF2127_OFFSET_TD_MN		1
> > +#define PCF2127_OFFSET_TD_HR		2
> > +#define PCF2127_OFFSET_TD_DM		3
> > +#define PCF2127_OFFSET_TD_DW		4
> > +#define PCF2127_OFFSET_TD_MO		5
> > +#define PCF2127_OFFSET_TD_YR		6
> 
> Same comment as for the alarms, I would simply remove the defines as
> they don't really carry any useful information.

Note that if I remove them, the patch for pcf2127_rtc_read_time() would look like this:

 	/* Clock integrity is not guaranteed when OSF flag is set. */
-	if (buf[PCF2127_REG_SC] & PCF2127_BIT_SC_OSF) {
+	if (buf[0] & PCF2127_BIT_SC_OSF) {
...
-		__func__, buf[PCF2127_REG_CTRL3], buf[PCF2127_REG_SC],
-		buf[PCF2127_REG_MN], buf[PCF2127_REG_HR],
-		buf[PCF2127_REG_DM], buf[PCF2127_REG_DW],
-		buf[PCF2127_REG_MO], buf[PCF2127_REG_YR]);
-
-	tm->tm_sec = bcd2bin(buf[PCF2127_REG_SC] & 0x7F);
-	tm->tm_min = bcd2bin(buf[PCF2127_REG_MN] & 0x7F);
-	tm->tm_hour = bcd2bin(buf[PCF2127_REG_HR] & 0x3F); /* rtc hr 0-23 */
-	tm->tm_mday = bcd2bin(buf[PCF2127_REG_DM] & 0x3F);
-	tm->tm_wday = buf[PCF2127_REG_DW] & 0x07;
-	tm->tm_mon = bcd2bin(buf[PCF2127_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
-	tm->tm_year = bcd2bin(buf[PCF2127_REG_YR]);
+		__func__, ctrl3, buf[0],
+		buf[1], buf[2],
+		buf[3], buf[4],
+		buf[5], buf[PCF2127_OFFSET_TD_YR]);
+
+	tm->tm_sec = bcd2bin(buf[0] & 0x7F);
+	tm->tm_min = bcd2bin(buf[1] & 0x7F);
+	tm->tm_hour = bcd2bin(buf[2] & 0x3F); /* rtc hr 0-23 */
+	tm->tm_mday = bcd2bin(buf[3] & 0x3F);
+	tm->tm_wday = buf[4] & 0x07;
+	tm->tm_mon = bcd2bin(buf[5] & 0x1F) - 1; /* rtc mn 1-12 */
+	tm->tm_year = bcd2bin(buf[6]);

Do you still want to remove the defines then?


> > +/* Time and date registers bits */
> >  #define PCF2127_BIT_SC_OSF			BIT(7)
> > -#define PCF2127_REG_MN			0x04
> > -#define PCF2127_REG_HR			0x05
> > -#define PCF2127_REG_DM			0x06
> > -#define PCF2127_REG_DW			0x07
> > -#define PCF2127_REG_MO			0x08
> > -#define PCF2127_REG_YR			0x09
> >  /* Alarm registers */
> >  #define PCF2127_REG_ALARM_SC		0x0A
> >  #define PCF2127_REG_ALARM_MN		0x0B
> > @@ -106,6 +109,7 @@ struct pcf21xx_config {
> >  	int max_register;
> >  	unsigned int has_nvmem:1;
> >  	unsigned int has_bit_wd_ctl_cd0:1;
> > +	u8 regs_td_base; /* Time/data base registers. */
> >  };
> >  
> >  struct pcf2127 {
> > @@ -125,27 +129,31 @@ struct pcf2127 {
> >  static int pcf2127_rtc_read_time(struct device *dev, struct rtc_time *tm)
> >  {
> >  	struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
> > -	unsigned char buf[10];
> > +	unsigned char buf[7];
> > +	unsigned int ctrl3;
> >  	int ret;
> >  
> >  	/*
> >  	 * Avoid reading CTRL2 register as it causes WD_VAL register
> >  	 * value to reset to 0 which means watchdog is stopped.
> >  	 */
> > -	ret = regmap_bulk_read(pcf2127->regmap, PCF2127_REG_CTRL3,
> > -			       (buf + PCF2127_REG_CTRL3),
> > -			       ARRAY_SIZE(buf) - PCF2127_REG_CTRL3);
> > -	if (ret) {
> > -		dev_err(dev, "%s: read error\n", __func__);
> > +	ret = regmap_read(pcf2127->regmap, PCF2127_REG_CTRL3, &ctrl3);
> > +	if (ret)
> >  		return ret;
> > -	}
> >  
> > -	if (buf[PCF2127_REG_CTRL3] & PCF2127_BIT_CTRL3_BLF)
> > +	if (ctrl3 & PCF2127_BIT_CTRL3_BLF)
> >  		dev_info(dev,
> >  			"low voltage detected, check/replace RTC battery.\n");
> >  
> > +	ret = regmap_bulk_read(pcf2127->regmap, pcf2127->cfg->regs_td_base,
> > +			       buf, sizeof(buf));
> > +	if (ret) {
> > +		dev_err(dev, "%s: read error\n", __func__);
> > +		return ret;
> > +	}
> > +
> >  	/* Clock integrity is not guaranteed when OSF flag is set. */
> > -	if (buf[PCF2127_REG_SC] & PCF2127_BIT_SC_OSF) {
> > +	if (buf[PCF2127_OFFSET_TD_SC] & PCF2127_BIT_SC_OSF) {
> >  		/*
> >  		 * no need clear the flag here,
> >  		 * it will be cleared once the new date is saved
> > @@ -158,18 +166,18 @@ static int pcf2127_rtc_read_time(struct device *dev, struct rtc_time *tm)
> >  	dev_dbg(dev,
> >  		"%s: raw data is cr3=%02x, sec=%02x, min=%02x, hr=%02x, "
> >  		"mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
> > -		__func__, buf[PCF2127_REG_CTRL3], buf[PCF2127_REG_SC],
> > -		buf[PCF2127_REG_MN], buf[PCF2127_REG_HR],
> > -		buf[PCF2127_REG_DM], buf[PCF2127_REG_DW],
> > -		buf[PCF2127_REG_MO], buf[PCF2127_REG_YR]);
> > -
> > -	tm->tm_sec = bcd2bin(buf[PCF2127_REG_SC] & 0x7F);
> > -	tm->tm_min = bcd2bin(buf[PCF2127_REG_MN] & 0x7F);
> > -	tm->tm_hour = bcd2bin(buf[PCF2127_REG_HR] & 0x3F); /* rtc hr 0-23 */
> > -	tm->tm_mday = bcd2bin(buf[PCF2127_REG_DM] & 0x3F);
> > -	tm->tm_wday = buf[PCF2127_REG_DW] & 0x07;
> > -	tm->tm_mon = bcd2bin(buf[PCF2127_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
> > -	tm->tm_year = bcd2bin(buf[PCF2127_REG_YR]);
> > +		__func__, ctrl3, buf[PCF2127_OFFSET_TD_SC],
> > +		buf[PCF2127_OFFSET_TD_MN], buf[PCF2127_OFFSET_TD_HR],
> > +		buf[PCF2127_OFFSET_TD_DM], buf[PCF2127_OFFSET_TD_DW],
> > +		buf[PCF2127_OFFSET_TD_MO], buf[PCF2127_OFFSET_TD_YR]);
> > +
> > +	tm->tm_sec = bcd2bin(buf[PCF2127_OFFSET_TD_SC] & 0x7F);
> > +	tm->tm_min = bcd2bin(buf[PCF2127_OFFSET_TD_MN] & 0x7F);
> > +	tm->tm_hour = bcd2bin(buf[PCF2127_OFFSET_TD_HR] & 0x3F); /* rtc hr 0-23 */
> 
> You can drop the comment

Done

> 
> > +	tm->tm_mday = bcd2bin(buf[PCF2127_OFFSET_TD_DM] & 0x3F);
> > +	tm->tm_wday = buf[PCF2127_OFFSET_TD_DW] & 0x07;
> > +	tm->tm_mon = bcd2bin(buf[PCF2127_OFFSET_TD_MO] & 0x1F) - 1; /* rtc mn 1-12 */
> 
> This comment too.

Done

> 
> > +	tm->tm_year = bcd2bin(buf[PCF2127_OFFSET_TD_YR]);
> >  	tm->tm_year += 100;
> >  
> >  	dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
> > @@ -207,7 +215,7 @@ static int pcf2127_rtc_set_time(struct device *dev, struct rtc_time *tm)
> >  	buf[i++] = bin2bcd(tm->tm_year - 100);
> >  
> >  	/* write register's data */
> > -	err = regmap_bulk_write(pcf2127->regmap, PCF2127_REG_SC, buf, i);
> > +	err = regmap_bulk_write(pcf2127->regmap, pcf2127->cfg->regs_td_base, buf, i);
> >  	if (err) {
> >  		dev_err(dev,
> >  			"%s: err=%d", __func__, err);
> > @@ -650,11 +658,13 @@ static struct pcf21xx_config pcf21xx_cfg[] = {
> >  		.max_register = 0x1d,
> >  		.has_nvmem = 1,
> >  		.has_bit_wd_ctl_cd0 = 1,
> > +		.regs_td_base = PCF2127_REG_TIME_DATE_BASE,
> >  	},
> >  	[PCF2129] = {
> >  		.max_register = 0x19,
> >  		.has_nvmem = 0,
> >  		.has_bit_wd_ctl_cd0 = 0,
> > +		.regs_td_base = PCF2127_REG_TIME_DATE_BASE,
> >  	},
> >  };
> >  
> > -- 
> > 2.30.2
> > 
> 
> -- 
> Alexandre Belloni, co-owner and COO, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
> 


-- 
Hugo Villeneuve <hugo@...ovil.com>

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