On Fri, 20 Jan 2023 18:01:35 +0100
Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx> wrote:
> On 15/12/2022 10:02:11-0500, Hugo Villeneuve wrote:
> > From: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
> >
> > Make sure the device we are probing is really the device we are
> > interested in.
> >
> > Signed-off-by: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
> > ---
> > drivers/rtc/rtc-pcf2127.c | 20 ++++++++++++++++++++
> > 1 file changed, 20 insertions(+)
> >
> > diff --git a/drivers/rtc/rtc-pcf2127.c b/drivers/rtc/rtc-pcf2127.c
> > index 241189ee4a05..e4b78b9c03f9 100644
> > --- a/drivers/rtc/rtc-pcf2127.c
> > +++ b/drivers/rtc/rtc-pcf2127.c
> > @@ -193,11 +193,13 @@ struct pcf21xx_config {
> > unsigned int has_nvmem:1;
> > unsigned int has_bit_wd_ctl_cd0:1;
> > unsigned int has_int_a_b:1; /* PCF2131 supports two interrupt outputs. */
> > + unsigned int has_reset_reg:1; /* If variant has a reset register. */
> > u8 regs_td_base; /* Time/data base registers. */
> > u8 regs_alarm_base; /* Alarm function base registers. */
> > u8 reg_wd_ctl; /* Watchdog control register. */
> > u8 reg_wd_val; /* Watchdog value register. */
> > u8 reg_clkout; /* Clkout register. */
> > + u8 reg_reset; /* Reset register if available. */
> > unsigned int ts_count;
> > struct pcf21xx_ts_config ts[4];
> > struct attribute_group attribute_group;
> > @@ -882,6 +884,7 @@ static struct pcf21xx_config pcf21xx_cfg[] = {
> > .has_nvmem = 1,
> > .has_bit_wd_ctl_cd0 = 1,
> > .has_int_a_b = 0,
> > + .has_reset_reg = 0,
> > .regs_td_base = PCF2127_REG_TIME_DATE_BASE,
> > .regs_alarm_base = PCF2127_REG_ALARM_BASE,
> > .reg_wd_ctl = PCF2127_REG_WD_CTL,
> > @@ -906,6 +909,7 @@ static struct pcf21xx_config pcf21xx_cfg[] = {
> > .has_nvmem = 0,
> > .has_bit_wd_ctl_cd0 = 0,
> > .has_int_a_b = 0,
> > + .has_reset_reg = 0,
> > .regs_td_base = PCF2127_REG_TIME_DATE_BASE,
> > .regs_alarm_base = PCF2127_REG_ALARM_BASE,
> > .reg_wd_ctl = PCF2127_REG_WD_CTL,
> > @@ -930,11 +934,13 @@ static struct pcf21xx_config pcf21xx_cfg[] = {
> > .has_nvmem = 0,
> > .has_bit_wd_ctl_cd0 = 0,
> > .has_int_a_b = 1,
> > + .has_reset_reg = 1,
> > .regs_td_base = PCF2131_REG_TIME_DATE_BASE,
> > .regs_alarm_base = PCF2131_REG_ALARM_BASE,
> > .reg_wd_ctl = PCF2131_REG_WD_CTL,
> > .reg_wd_val = PCF2131_REG_WD_VAL,
> > .reg_clkout = PCF2131_REG_CLKOUT,
> > + .reg_reset = PCF2131_REG_SR_RESET,
> > .ts_count = 4,
> > .ts[0] = {
> > .regs_base = PCF2131_REG_TS1_BASE,
> > @@ -1075,6 +1081,20 @@ static int pcf2127_probe(struct device *dev, struct regmap *regmap,
> > clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, pcf2127->rtc->features);
> > clear_bit(RTC_FEATURE_ALARM, pcf2127->rtc->features);
> >
> > + /* Read device signature if available. */
> > + if (pcf2127->cfg->has_reset_reg) {
> > + ret = regmap_read(pcf2127->regmap, pcf2127->cfg->reg_reset, &val);
> > + if (ret < 0) {
> > + dev_err(dev, "reading RESET register failed\n");
>
> This is too verbose, please cut down on the number of strings you are
> adding.
See comment below.
>
> > + return ret;
> > + }
> > +
> > + if (val != PCF2131_SR_RESET_READ_PATTERN) {
> > + dev_err(dev, "invalid device signature: $%02X\n", (u8)val);
>
> I'm also not convinced this is actually useful. This may have to be
> updated for the next rtc the driver will support and what if this
> contradicts what the device tree is claiming at this address?
I will drop that section.
> > + return -ENODEV;
> > + }
> > + }
> > +
> > if (alarm_irq > 0) {
> > unsigned long flags;
> >
> > --
> > 2.30.2
> >
>
> --
> Alexandre Belloni, co-owner and COO, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
>
--
Hugo Villeneuve <hugo@xxxxxxxxxxx>
