linux-kernel - Re: [PATCH v3 07/14] rtc: pcf2127: add support for PCF2131 RTC

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Message-Id: <20230123122701.1548311030689f85b733fcbb@hugovil.com>
Date:   Mon, 23 Jan 2023 12:27:01 -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 07/14] rtc: pcf2127: add support for PCF2131 RTC

On Fri, 20 Jan 2023 19:57:07 +0100
Alexandre Belloni <alexandre.belloni@...tlin.com> wrote:

> On 15/12/2022 10:02:08-0500, Hugo Villeneuve wrote:
> >  	  PCF2127 has an additional feature of 512 bytes battery backed
> > diff --git a/drivers/rtc/rtc-pcf2127.c b/drivers/rtc/rtc-pcf2127.c
> > index 3265878edc48..4148e135f935 100644
> > --- a/drivers/rtc/rtc-pcf2127.c
> > +++ b/drivers/rtc/rtc-pcf2127.c
> > @@ -1,16 +1,26 @@
> >  // SPDX-License-Identifier: GPL-2.0-only
> >  /*
> > - * An I2C and SPI driver for the NXP PCF2127/29 RTC
> > + * An I2C and SPI driver for the NXP PCF2127/29/31 RTC
> >   * Copyright 2013 Til-Technologies
> > + * Copyright 2021 DimOnOff
> 
> For the record, I don't really like that because git will be the
> authoritative source for the copyright. This will only end up being
> outdated info (as it is already)

Removed.

> 
> >   *
> >   * Author: Renaud Cerrato <r.cerrato@...-technologies.fr>
> >   *
> >   * Watchdog and tamper functions
> >   * Author: Bruno Thomsen <bruno.thomsen@...il.com>
> >   *
> > + * PCF2131 support
> > + * Author: Hugo Villeneuve <hvilleneuve@...onoff.com>
> > + *
> >   * based on the other drivers in this same directory.
> >   *
> > - * Datasheet: https://www.nxp.com/docs/en/data-sheet/PCF2127.pdf
> > + * Datasheets: https://www.nxp.com/docs/en/data-sheet/PCF2127.pdf
> > + *             https://www.nxp.com/docs/en/data-sheet/PCF2131DS.pdf
> > + */
> > +
> > +/*
> > + * The following features are not yet implemented for the PCF2131:
> > + *   - support for 1/100th seconds
> 
> This will never be added so I would remove that comment

Done.

> 
> >   */
> >  
> >  #include <linux/i2c.h>
> > @@ -43,8 +53,30 @@
> >  #define PCF2127_BIT_CTRL3_BLF			BIT(2)
> >  #define PCF2127_BIT_CTRL3_BF			BIT(3)
> >  #define PCF2127_BIT_CTRL3_BTSE			BIT(4)
> > +/* Control register 4 */
> > +#define PCF2131_REG_CTRL4		0x03
> > +#define PCF2131_BIT_CTRL4_TSF4			BIT(4)
> > +#define PCF2131_BIT_CTRL4_TSF3			BIT(5)
> > +#define PCF2131_BIT_CTRL4_TSF2			BIT(6)
> > +#define PCF2131_BIT_CTRL4_TSF1			BIT(7)
> > +/* Control register 5 */
> > +#define PCF2131_REG_CTRL5		0x04
> > +#define PCF2131_BIT_CTRL5_TSIE4			BIT(4)
> > +#define PCF2131_BIT_CTRL5_TSIE3			BIT(5)
> > +#define PCF2131_BIT_CTRL5_TSIE2			BIT(6)
> > +#define PCF2131_BIT_CTRL5_TSIE1			BIT(7)
> > +/* Software reset register */
> > +#define PCF2131_REG_SR_RESET		0x05
> > +#define PCF2131_SR_RESET_READ_PATTERN	0b00100100 /* Fixed pattern. */
> > +#define PCF2131_SR_RESET_RESET_CMD	0x2C /* SR is bit 3. */
> >  /* Time and date registers */
> >  #define PCF2127_REG_TIME_DATE_BASE	0x03
> > +#define PCF2131_REG_TIME_DATE_BASE	0x07 /* Register 0x06 is 100th seconds,
> > +					      * but we do not support it. By
> > +					      * using offset 0x07, we can be
> > +					      * compatible with existing
> > +					      * time/date functions.
> > +					      */
> 
> Because we will never support 100th of seconds, this comment is not
> useful

Removed.

> 
> >  /* Time and date registers offsets (starting from base register) */
> >  #define PCF2127_OFFSET_TD_SC		0
> >  #define PCF2127_OFFSET_TD_MN		1
> > @@ -57,6 +89,7 @@
> >  #define PCF2127_BIT_SC_OSF			BIT(7)
> >  /* Alarm registers */
> >  #define PCF2127_REG_ALARM_BASE		0x0A
> > +#define PCF2131_REG_ALARM_BASE		0x0E
> 
> I'd keep the defines ordered by address, so you could move all the
> PCF2131 defines after the PCF2127 ones

Done.


> 
> >  /* Alarm registers offsets (starting from base register) */
> >  #define PCF2127_OFFSET_ALARM_SC		0
> >  #define PCF2127_OFFSET_ALARM_MN		1
> > @@ -67,16 +100,26 @@
> >  #define PCF2127_BIT_ALARM_AE			BIT(7)
> >  /* CLKOUT control register */
> >  #define PCF2127_REG_CLKOUT		0x0f
> > +#define PCF2131_REG_CLKOUT		0x13
> >  #define PCF2127_BIT_CLKOUT_OTPR			BIT(5)
> >  /* Watchdog registers */
> >  #define PCF2127_REG_WD_CTL		0x10
> > +#define PCF2131_REG_WD_CTL		0x35
> >  #define PCF2127_BIT_WD_CTL_TF0			BIT(0)
> >  #define PCF2127_BIT_WD_CTL_TF1			BIT(1)
> >  #define PCF2127_BIT_WD_CTL_CD0			BIT(6)
> >  #define PCF2127_BIT_WD_CTL_CD1			BIT(7)
> >  #define PCF2127_REG_WD_VAL		0x11
> > +#define PCF2131_REG_WD_VAL		0x36
> >  /* Tamper timestamp1 registers */
> >  #define PCF2127_REG_TS1_BASE		0x12
> > +#define PCF2131_REG_TS1_BASE		0x14
> > +/* Tamper timestamp2 registers */
> > +#define PCF2131_REG_TS2_BASE		0x1B
> > +/* Tamper timestamp3 registers */
> > +#define PCF2131_REG_TS3_BASE		0x22
> > +/* Tamper timestamp4 registers */
> > +#define PCF2131_REG_TS4_BASE		0x29
> >  /* Tamper timestamp registers common offsets (starting from base register) */
> >  #define PCF2127_OFFSET_TS_CTL		0
> >  #define PCF2127_OFFSET_TS_SC		1
> > @@ -92,11 +135,22 @@
> >   * RAM registers
> >   * PCF2127 has 512 bytes general-purpose static RAM (SRAM) that is
> >   * battery backed and can survive a power outage.
> > - * PCF2129 doesn't have this feature.
> > + * PCF2129/31 doesn't have this feature.
> >   */
> >  #define PCF2127_REG_RAM_ADDR_MSB	0x1A
> >  #define PCF2127_REG_RAM_WRT_CMD		0x1C
> >  #define PCF2127_REG_RAM_RD_CMD		0x1D
> > +/* Interrupt mask registers */
> > +#define PCF2131_REG_INT_A_MASK1		0x31
> > +#define PCF2131_REG_INT_A_MASK2		0x32
> > +#define PCF2131_REG_INT_B_MASK1		0x33
> > +#define PCF2131_REG_INT_B_MASK2		0x34
> > +#define PCF2131_BIT_INT_BLIE		BIT(0)
> > +#define PCF2131_BIT_INT_BIE		BIT(1)
> > +#define PCF2131_BIT_INT_AIE		BIT(2)
> > +#define PCF2131_BIT_INT_WD_CD		BIT(3)
> > +#define PCF2131_BIT_INT_SI		BIT(4)
> > +#define PCF2131_BIT_INT_MI		BIT(5)
> >  
> >  /* Watchdog timer value constants */
> >  #define PCF2127_WD_VAL_STOP		0
> > @@ -110,6 +164,14 @@
> >  		PCF2127_BIT_CTRL2_AF | \
> >  		PCF2127_BIT_CTRL2_WDTF | \
> >  		PCF2127_BIT_CTRL2_TSF2)
> > +#define PCF2131_CTRL2_IRQ_MASK ( \
> > +		PCF2127_BIT_CTRL2_AF | \
> > +		PCF2127_BIT_CTRL2_WDTF)
> > +#define PCF2131_CTRL4_IRQ_MASK ( \
> > +		PCF2131_BIT_CTRL4_TSF4 | \
> > +		PCF2131_BIT_CTRL4_TSF3 | \
> > +		PCF2131_BIT_CTRL4_TSF2 | \
> > +		PCF2131_BIT_CTRL4_TSF1)
> >  
> >  struct pcf21xx_ts_config {
> >  	u8 regs_base; /* Base register to read timestamp values. */
> > @@ -370,7 +432,7 @@ static int pcf2127_wdt_set_timeout(struct watchdog_device *wdd,
> >  }
> >  
> >  static const struct watchdog_info pcf2127_wdt_info = {
> > -	.identity = "NXP PCF2127/PCF2129 Watchdog",
> > +	.identity = "NXP PCF2127/29/31 Watchdog",
> 
> This change may break userspace tools as this is exposed to userspace

Ok, removed.


> Alexandre Belloni, co-owner and COO, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com