Re: [PATCH v4 2/5] platform: arm64: Add driver for EC found on Qualcomm reference devices

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 3/13/26 11:29 AM, Anvesh Jain P wrote:
> From: Sibi Sankar <sibi.sankar@oss.qualcomm.com>
> 
> Add Embedded controller driver support for Hamoa/Purwa/Glymur qualcomm
> reference boards. It handles fan control, temperature sensors, access
> to EC state changes and supports reporting suspend entry/exit to the
> EC.
> 
> Co-developed-by: Maya Matuszczyk <maccraft123mc@gmail.com>
> Signed-off-by: Maya Matuszczyk <maccraft123mc@gmail.com>
> Signed-off-by: Sibi Sankar <sibi.sankar@oss.qualcomm.com>
> Co-developed-by: Anvesh Jain P <anvesh.p@oss.qualcomm.com>
> Signed-off-by: Anvesh Jain P <anvesh.p@oss.qualcomm.com>
> ---

[...]

> + * ------------------------------------------------------------------------------
> + * | Offset		| Name		| Description				|
> + * ------------------------------------------------------------------------------
> + * | 0x00		| Byte count	| Number of bytes in response		|
> + * |			|		| (exluding byte count)			|
> + * ------------------------------------------------------------------------------
> + * | 0x02 (LSB)	| EC Thermal	| Bit 0-1: Number of fans		|
> + * | 0x3		| Capabilities	| Bit 2-4: Type of fan			|
> + * |			|		| Bit 5-6: Reserved			|
> + * |			|		| Bit 7: Data Valid/Invalid		|
> + * |			|		|	 (Valid - 1, Invalid - 0)	|
> + * |			|		| Bit 8-15: Thermistor 0 - 7 presence	|
> + * |			|		|	    (0 present, 1 absent)	|
						     ^ huh??

I see that it's not currently used, but I think flipping these
bits would make it easier to comprehend down the line

[...]

> +	default:
> +		dev_dbg(dev, "Unknown EC event: %d\n", val);

Maybe dev_notice(), this would be good to log

> +		break;
> +	}
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int qcom_ec_sci_evt_control(struct device *dev, bool enable)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	u8 control = enable ? 1 : 0;
> +	int ret;
> +
> +	ret = i2c_smbus_write_byte_data(client, EC_SCI_EVT_CONTROL_CMD, control);
> +
> +	return ret;

return i2c_smbus_write_byte_data(client, EC_SCI_EVT_CONTROL_CMD, !!enable);

[...]

> +static int qcom_ec_resume(struct device *dev)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	int ret;
> +
> +	ret = i2c_smbus_write_byte_data(client, EC_MODERN_STANDBY_CMD, EC_MODERN_STANDBY_ENTER);
> +
> +	return ret;

In a pattern like this, unless you have some error checking/logging to
do, you can just return directly

[...]

> +	ret = qcom_ec_read_fw_version(dev);
> +	if (ret < 0)
> +		return dev_err_probe(dev, ret, "Failed to read ec firmware version\n");

"EC"

[...]

> +	for (i = 0; i < ec->thermal_cap.fan_cnt; i++) {
> +		struct qcom_ec_cooling_dev *ec_cdev = &ec->ec_cdev[i];
> +		char name[EC_FAN_NAME_SIZE];
> +
> +		snprintf(name, EC_FAN_NAME_SIZE, "qcom_ec_fan_%d", i);
> +		ec_cdev->fan_id = i + 1;
> +		ec_cdev->parent_dev = dev;
> +
> +		ec_cdev->cdev = thermal_cooling_device_register(name, ec_cdev,
> +								&qcom_ec_thermal_ops);
> +		if (IS_ERR(ec_cdev->cdev)) {
> +			dev_err_probe(dev, PTR_ERR(cdev),
> +				      "Thermal cooling device registration failed\n");
> +			ret = -EINVAL;
> +			goto unroll_cooling_dev;
> +		}
> +	}
> +
> +	return 0;
> +
> +unroll_cooling_dev:

For those cases, one would usually add add a devres-managed version of
the helper (devm_foo_bar()), removing the need to repeat this in the 
driver remove callback as well

Konrad