Re: [PATCH v5 3/3] i2c/busses/i2c-icy: Add LTC2990 present on 2019 board revision

Geert Uytterhoeven
2019-08-20T09:18:36Z

On Mon, Aug 19, 2019 at 2:17 PM Max Staudt <max@enpas.org> wrote:
> Since the 2019 a1k.org community re-print of these PCBs sports an
> LTC2990 hwmon chip as an example use case, let this driver autoprobe
> for that as well. If it is present, modprobing ltc2990 is sufficient.
>
> The property_entry enables the three additional inputs available on
> this particular board:
>
> in1 will be the voltage of the 5V rail, divided by 2.
> in2 will be the voltage of the 12V rail, divided by 4.
> temp3 will be measured using a PCB loop next the chip.
>
> v5: Style
>
> v4: Style
> Added other possible addresses for LTC2990.
>
> v3: Merged with initial LTC2990 support on ICY.
> Moved defaults from platform_data to swnode.
> Added note to Kconfig.
>
> Signed-off-by: Max Staudt <max@enpas.org>

Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>

One comment below...

> --- a/drivers/i2c/busses/i2c-icy.c
> +++ b/drivers/i2c/busses/i2c-icy.c

> @@ -141,6 +166,35 @@ static int icy_probe(struct zorro_dev *z,
> dev_info(&z->dev, "ICY I2C controller at %pa, IRQ not implemented\n",
> &z->resource.start);
>
> + /*
> + * The 2019 a1k.org PCBs have an LTC2990 at 0x4c, so start
> + * it automatically once ltc2990 is modprobed.
> + *
> + * in0 is the voltage of the internal 5V power supply.
> + * temp1 is the temperature inside the chip.
> + *
> + * See property_entry above for in1, in2, temp3.
> + */
> + new_fwnode = fwnode_create_software_node(icy_ltc2990_props, NULL);
> + if (IS_ERR(new_fwnode)) {
> + dev_info(&z->dev, "Failed to create fwnode for LTC2990, error: %ld\n",
> + PTR_ERR(new_fwnode));
> + } else {
> + /*
> + * Store the fwnode so we can destroy it on .remove().
> + * Only store it on success, as fwnode_remove_software_node()
> + * is NULL safe, but not PTR_ERR safe.
> + */
> + i2c->ltc2990_fwnode = new_fwnode;
> + ltc2990_info.fwnode = new_fwnode;
> +
> + i2c->ltc2990_client =
> + i2c_new_probed_device(&i2c->adapter,
> + &ltc2990_info,
> + icy_ltc2990_addresses,
> + NULL);
> + }
> +
> return 0;
> }

Since commit d3e1b617ae20c459 ("i2c: allow specify device properties in
i2c_board_info"), the properties could be provided by info->properties, too.
However, according to the comments for device_add_properties(), this is
valid only if there is a real firmware node present.

If that is true, Max' use is correct, while e.g. commit 6a7836ba7fb4abf6
("ARM: imx: pca100: use device properties for at24 eeprom") isn't?

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