Re: [RFC net-next 07/15] net: lora: Add Semtech SX1276

Andreas Färber
2018-07-01T12:03:08Z

Am 01.07.2018 um 13:07 schrieb Andreas Färber:
> diff --git a/drivers/net/lora/sx1276.c b/drivers/net/lora/sx1276.c
> new file mode 100644
> index 000000000000..d6732111247a
> --- /dev/null
> +++ b/drivers/net/lora/sx1276.c
[...]
> +static int sx1276_probe(struct spi_device *spi)
> +{
> + struct net_device *netdev;
> + struct sx1276_priv *priv;
> + int rst, dio[6], ret, model, i;
> + u32 freq_xosc, freq_band;
> + unsigned long long freq_rf;
> + u8 val;
> +
> + rst = of_get_named_gpio(spi->dev.of_node, "reset-gpio", 0);
> + if (rst == -ENOENT)
> + dev_warn(&spi->dev, "no reset GPIO available, ignoring");
> +
> + for (i = 0; i < 6; i++) {
> + dio[i] = of_get_named_gpio(spi->dev.of_node, "dio-gpios", i);
> + if (dio[i] == -ENOENT)
> + dev_dbg(&spi->dev, "DIO%d not available, ignoring", i);
> + else {
> + ret = gpio_direction_input(dio[i]);
> + if (ret)
> + dev_err(&spi->dev, "couldn't set DIO%d to input", i);
> + }
> + }
> +
> + if (gpio_is_valid(rst)) {
> + gpio_set_value(rst, 1);
> + udelay(100);
> + gpio_set_value(rst, 0);
> + msleep(5);
> + }
> +
> + spi->bits_per_word = 8;
> + spi_setup(spi);
> +
> + ret = sx1276_read_single(spi, REG_VERSION, &val);
> + if (ret) {
> + dev_err(&spi->dev, "version read failed");
> + return ret;
> + }
> +
> + if (val == 0x22)
> + model = 1272;
> + else {
> + if (gpio_is_valid(rst)) {
> + gpio_set_value(rst, 0);
> + udelay(100);
> + gpio_set_value(rst, 1);
> + msleep(5);
> + }
> +
> + ret = sx1276_read_single(spi, REG_VERSION, &val);
> + if (ret) {
> + dev_err(&spi->dev, "version read failed");
> + return ret;
> + }
> +
> + if (val == 0x12)
> + model = 1276;
> + else {
> + dev_err(&spi->dev, "transceiver not recognized (RegVersion = 0x%02x)", (unsigned)val);
> + return -EINVAL;
> + }
> + }
[snip]

To counter my own point, this file of course still has leftover model
detection heuristics; should check for the of_device_id match instead!
SX1272 vs. SX1276 have the reset pin inverted, so - knowing which model
it's supposed to be - we can do the right reset from the start and, if
it doesn't work, report an error to the user.

Also I should update that code to use gpiod, as seen in later patches.

Cheers,
Andreas

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