Re: [PATCH v4 2/2] iio: adc: add MAX40080 current-sense amplifier driver

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Fri, Jul 17, 2026 at 03:38:49PM +0300, Stefan Popa wrote:
> The MAX40080 is a bidirectional current-sense amplifier with an
> integrated 12-bit ADC and an I2C/SMBus interface. It measures the
> voltage across an external shunt resistor and the input bus voltage,
> storing the results in an internal FIFO.
> 
> No existing IIO driver covers this device or a register-compatible part.
> The closest relatives target different silicon with incompatible register
> maps and feature sets: max9611 is a unidirectional high-side sensor with a
> die-temperature channel and MUX-selected gain and no FIFO/PEC, while
> max34408 is an 8-bit multi-channel current monitor. The MAX40080 has a
> device-specific register map with bidirectional 13-bit current, a 64-entry
> FIFO, PEC, a single-measurement mode triggered by an SMBus Quick Command,
> and two selectable input ranges, so it warrants its own driver.
> 
> Add a direct-mode IIO driver exposing the current and voltage channels
> with raw and scale attributes, a configurable oversampling (digital
> averaging) ratio, and PEC-protected register access. The two selectable
> current-sense ranges are exposed through scale/scale_available; the
> current scale is derived from the shunt-resistor-micro-ohms device-tree
> property.

...

> +struct max40080_state {
> +	struct i2c_client *client;
> +	/* Serializes read-modify-write access to the CFG register. */
> +	struct mutex lock;
> +	u32 shunt_resistor_uOhm;
> +	/*
> +	 * Cached configuration, also used to restore the device on resume after
> +	 * a suspend that may have cut its power: the selected RANGE index and
> +	 * the oversampling ratio.
> +	 */
> +	unsigned int range;
> +	int oversampling_ratio;
> +	/*
> +	 * Precomputed current scale (mA per code) for each RANGE setting, as
> +	 * {integer, nano} pairs for IIO_VAL_INT_PLUS_NANO. The range is
> +	 * selected by writing the corresponding scale.
> +	 */
> +	int current_scale[ARRAY_SIZE(max40080_csa_gain)][2];

> +	/* DMA-safe buffer for i2c_smbus_read_i2c_block_data(). */
> +	u8 buf[4] ____cacheline_aligned;

Why don't you use the specific IIO macro for this?
Do you have internal reviews for this patch series?

> +};

-- 
With Best Regards,
Andy Shevchenko