[PATCH 2/2] power: supply: Add Lenovo Yoga C630 EC driver

[Sebastian Reichel]

Hi,

[+Cc Lee Jones, DRI devel]

On Tue, Aug 09, 2022 at 10:05:00PM -0500, Bjorn Andersson wrote:
> The Qualcomm Snapdragon-based Lenovo Yoga C630 has some sort of EC
> providing AC-adapter and battery status, as well as USB Type-C altmode
> notifications for Displayport operation.
> 
> The Yoga C630 ships with Windows, where these operations primarily are
> implemented in ACPI, but due to various issues with the hardware
> representation therein it's not possible to run Linux on this
> information. As such this is a best-effort re-implementation of these
> operations, based on the register map expressed in ACPI and a fair
> amount of trial and error.
> 
> Signed-off-by: Bjorn Andersson <bjorn.andersson at linaro.org>
> ---
> [...]
> +	val = yoga_c630_ec_read8(ec, LENOVO_EC_BAT_ATTRIBUTES);
> +	if (val < 0)
> +		goto out_unlock;
> +	ec->unit_ma = val & LENOVO_EC_BAT_ATTR_UNIT_IS_MA;
> +	if (!ec->unit_ma)
> +		ec->scale = 1000;
> +	else
> +		ec->scale = 1;

Since I'm not sure how much of information was gained by reverse
engineering: Is this really milliamps vs microamps and not milliamps
vs milliwatt? SBS batteries usually report either mA or mW.

> [...]
> +	case POWER_SUPPLY_PROP_SERIAL_NUMBER:
> +		val->strval = "05072018";
> +		break;

why is this hardcoded? :)

> [...]
> +	device_for_each_child_node(dev, fwnode) {
> +		ret = fwnode_property_read_u32(fwnode, "reg", &port);
> +		if (ret < 0)
> +			continue;
> +
> +		/* Got multiple ports, but altmode is only possible on port 1 */
> +		if (port != 1)
> +			continue;
> +
> +		ec->bridge.funcs = &yoga_c630_ec_bridge_funcs;
> +		ec->bridge.of_node = to_of_node(fwnode);
> +		ec->bridge.ops = DRM_BRIDGE_OP_HPD;
> +		ec->bridge.type = DRM_MODE_CONNECTOR_USB;
> +
> +		ret = devm_drm_bridge_add(dev, &ec->bridge);
> +		if (ret) {
> +			dev_err(dev, "failed to register drm bridge\n");
> +			fwnode_handle_put(fwnode);
> +			return ret;
> +		}

I wonder if DRM people want to see this in drivers/gpu/drm/bridge.
Maybe it's better to make this a MFD driver?

> [...]

-- Sebastian
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