On Wed, Sep 11, 2024 at 03:27:46PM +0800, Chen-Yu Tsai wrote:
> Add GPIO support to the simple helpers for the I2C OF component prober.
> Components that the prober intends to probe likely require their
> regulator supplies be enabled, and GPIOs be toggled to enable them or
> bring them out of reset before they will respond to probe attempts.
> Regulator supplies were handled in the previous patch.
>
> The assumption is that the same class of components to be probed are
> always connected in the same fashion with the same regulator supply
> and GPIO. The names may vary due to binding differences, but the
> physical layout does not change.
>
> This supports at most one GPIO pin. The user must specify the GPIO name,
> the polarity, and the amount of time to wait after the GPIO is toggled.
> Devices with more than one GPIO pin likely require specific power
> sequencing beyond what generic code can easily support.
...
> +static int i2c_of_probe_simple_get_gpiod(struct device *dev, struct device_node *node,
> + struct i2c_of_probe_simple_ctx *ctx)
> +{
> + struct fwnode_handle *fwnode = of_fwnode_handle(node);
> + struct gpio_desc *gpiod;
> + const char *con_id = NULL;
> +
> + /* NULL signals no GPIO needed */
> + if (!ctx->opts->gpio_name)
> + return 0;
> +
> + /* An empty string signals an unnamed GPIO */
> + if (strlen(ctx->opts->gpio_name))
You run for entire string in order to check the first byte only?
if (ctx->opts->gpio_name[0] == '\0')
con_id = NULL;
else
> + con_id = ctx->opts->gpio_name;
Also note, that comment is given in inverted condition to what you actually do
in the code. With my suggestion it looks better.
> + gpiod = fwnode_gpiod_get_index(fwnode, con_id, 0, GPIOD_ASIS, "i2c-of-prober");
> + if (IS_ERR(gpiod))
> + return PTR_ERR(gpiod);
> +
> + ctx->gpiod = gpiod;
> +
> + return 0;
> +}
...
> +static int i2c_of_probe_simple_set_gpio(struct device *dev, struct i2c_of_probe_simple_ctx *ctx)
> +{
> + int ret;
> +
> + if (!ctx->gpiod)
> + return 0;
> + dev_dbg(dev, "Setting GPIO\n");
> + ret = gpiod_direction_output_raw(ctx->gpiod, ctx->opts->gpio_high_to_enable ? 1 : 0);
Hmm... _raw() in use... Perhaps it's on a territory of Bart and Linus to review
and comment on this.
> + if (ret)
> + return ret;
> +
> + msleep(ctx->opts->post_reset_deassert_delay_ms);
> +
> + return 0;
> +}
--
With Best Regards,
Andy Shevchenko
