Re: [PATCH] aiodev: add driver for Rockchip SARADC

[Sascha Hauer <sha@pengutronix.de>]

Hi Michael,

On Thu, Jun 17, 2021 at 04:36:54PM +0200, Michael Riesch wrote:
> +static int rockchip_saradc_read(struct aiochannel *chan, int *val)
> +{
> +	struct rockchip_saradc_data *data;
> +	int timeout = SARADC_TIMEOUT;
> +	u32 value = 0;
> +	u32 control = 0;
> +	u32 mask;
> +
> +	if (!chan || !val)
> +		return -EINVAL;
> +
> +	data = container_of(chan->aiodev, struct rockchip_saradc_data, aiodev);
> +	if (!data)
> +		return -EINVAL;
> +
> +	rockchip_saradc_reg_wr(data, 8, SARADC_DLY_PU_SOC);
> +	rockchip_saradc_reg_wr(data,
> +			       (chan->index & SARADC_CTRL_CHN_MASK) |
> +				       SARADC_CTRL_IRQ_ENABLE |
> +				       SARADC_CTRL_POWER_CTRL,
> +			       SARADC_CTRL);
> +
> +	do {
> +		control = rockchip_saradc_reg_rd(data, SARADC_CTRL);
> +
> +		if (--timeout == 0)
> +			return -ETIMEDOUT;
> +		mdelay(1);
> +	} while (!(control & SARADC_CTRL_IRQ_STATUS));

You should do a timeout loop with

	u64 start = get_time_ns();

	do {
		if (is_timeout(start, 100 * MSECOND)
			return -ETIMEDOUT;
	} while(bar);

We don't have any way nor need to put the CPU into idle, so we can poll
as fast as we can.

> +
> +	mask = (1 << data->config->num_bits) - 1;
> +	value = rockchip_saradc_reg_rd(data, SARADC_DATA) & mask;
> +	rockchip_saradc_reg_wr(data, 0, SARADC_CTRL);
> +
> +	printf("Raw value: %d\n", value);

Debugging leftover.

> +fail_channels:
> +	kfree(data->channels);
> +	kfree(data->aiodev.channels);
> +
> +fail_data:
> +	kfree(data);
> +	return ret;
> +}
> +
> +static const struct rockchip_saradc_cfg rk3568_saradc_cfg = {
> +	.ref_voltage_mv = 1800,

>From looking at the downstream dts files this doesn't seem to be SoC
specific:

	&saradc {
        	status = "okay";
		vref-supply = <&vcca_1v8>;
	};

I suggest doing the same here.

> +	.num_bits = 10,
> +	.num_channels = 8,
> +};
> +
> +static const struct of_device_id of_rockchip_saradc_match[] = {
> +	{ .compatible = "rockchip,rk3568-saradc", .data = &rk3568_saradc_cfg },

The device nodes in the downstream Kernel also contain some clocks.
These should be handled in the driver.

Sascha

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