Hi Geert,
Thanks for feedback.
> Subject: Re: [PATCH v3 2/4] rtc: pcf85363: Add support for NXP pcf85263 rtc
>
> Hi Biju,
>
> CC nvmem maintainer
>
> On Thu, Dec 6, 2018 at 10:04 AM Biju Das <biju.das@xxxxxxxxxxxxxx> wrote:
> > Add support for NXP pcf85263 real-time clock. pcf85263 rtc is
> > compatible with pcf85363,except that pcf85363 has additional 64 bytes of
> RAM.
> >
> > 1 byte of nvmem is supported and exposed in sysfs (# is the instance
> > number,starting with 0): /sys/bus/nvmem/devices/pcf85x63-#/nvmem
> >
> > Signed-off-by: Biju Das <biju.das@xxxxxxxxxxxxxx>
> > ---
> > V1-->V2
> > * Incorporated Alexandre and Geert's review comment.
> > V2-->V3
> > * Incorporated Geert's review comment.
>
> Thanks for the update!
>
> > --- a/drivers/rtc/rtc-pcf85363.c
> > +++ b/drivers/rtc/rtc-pcf85363.c
> > @@ -120,6 +120,11 @@ struct pcf85363 {
> > struct regmap *regmap;
> > };
> >
> > +struct pcf85x63_config {
> > + struct regmap_config regmap;
> > + unsigned int num_nvram;
> > +};
> > +
> > static int pcf85363_rtc_read_time(struct device *dev, struct rtc_time
> > *tm) {
> > struct pcf85363 *pcf85363 = dev_get_drvdata(dev); @@ -311,25
> > +316,68 @@ static int pcf85363_nvram_write(void *priv, unsigned int
> offset, void *val,
> > val, bytes); }
> >
> > -static const struct regmap_config regmap_config = {
> > - .reg_bits = 8,
> > - .val_bits = 8,
> > - .max_register = 0x7f,
> > +static int pcf85x63_nvram_read(void *priv, unsigned int offset, void *val,
> > + size_t bytes)
>
> Given bytes should be 1, val should be a pointer to a single byte...
> What if bytes == 0?
I doubt we get "bytes==0" because of the checks in " drivers/nvmem/core.c"
Function " bin_attr_nvmem_read/ bin_attr_nvmem_write".
> > +{> + struct pcf85363 *pcf85363 = priv;
> > +
> > + return regmap_read(pcf85363->regmap, CTRL_RAMBYTE, val);
>
> However, regmap_read() has an unsigned int output parameter!
> So it's writing too many bytes, and only writing the actual data byte to the
> correct address on little-endian systems.
> Hence you need to use an intermediate variable to convert from unsigned int
> to byte.
OK. Will use an intermediate integer variable.
> > +}
> > +
> > +static int pcf85x63_nvram_write(void *priv, unsigned int offset, void *val,
> > + size_t bytes) {
> > + struct pcf85363 *pcf85363 = priv;
> > +
> > + return regmap_write(pcf85363->regmap, CTRL_RAMBYTE,
> > + *((unsigned int *)val));
>
> Likewise for writing.
>
> > +}
>
> BTW, while the nvmem_device_{read,write}() public API is documented, the
> nvmem_device.reg_{read,write}() driver API isn't.
> And the behavior might be confusing.
>
> E.g.
> * Return: length of successful bytes read on success and negative
> * error code on error.
>
> The public API seems to assume the driver API returns zero on success, and
> replaces the zero by the number of bytes requested.
> If the requested number of bytes is too large, a zero success would be
> converted to a value that's larger than the actual number of bytes
> transferred!
> However, the driver API can return a smaller (positive) number, which
> matches "standard" read/write() APIs.
>
> > +static const struct pcf85x63_config pcf_85263_config = {
> > + {
> > + .reg_bits = 8,
> > + .val_bits = 8,
> > + .max_register = 0x2f,
> > + },
> > + 1
>
> The "1" looks funny. Please use C99 initializers for all struct members.
OK will fix this.
> > +};
> > +
> > +static const struct pcf85x63_config pcf_85363_config = {
> > + {
> > + .reg_bits = 8,
> > + .val_bits = 8,
> > + .max_register = 0x7f,
> > + },
> > + 2
>
> Likewise.
OK will fix this.
Regards,
Biju
> The rest looks good to me, so
> Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
>
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-
> m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> -- Linus Torvalds
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