Re: [PATCH v3 net-next 5/8] mfd: zl3073x: Add functions to work with register mailboxes

Andrew Lunn
2025-04-16T17:32:25Z

> +/**
> + * zl3073x_mb_dpll_read - read given DPLL configuration to mailbox
> + * @zldev: pointer to device structure
> + * @index: DPLL index
> + *
> + * Reads configuration of given DPLL into DPLL mailbox.
> + *
> + * Context: Process context. Expects zldev->regmap_lock to be held by caller.
> + * Return: 0 on success, <0 on error
> + */
> +int zl3073x_mb_dpll_read(struct zl3073x_dev *zldev, u8 index)
> +{
> + int rc;

lockdep_assert_held(zldev->regmap_lock) is stronger than having a
comment. When talking about i2c and spi devices, it costs nothing, and
catches bugs early.

> +/*
> + * Mailbox operations
> + */
> +int zl3073x_mb_dpll_read(struct zl3073x_dev *zldev, u8 index);
> +int zl3073x_mb_dpll_write(struct zl3073x_dev *zldev, u8 index);
> +int zl3073x_mb_output_read(struct zl3073x_dev *zldev, u8 index);
> +int zl3073x_mb_output_write(struct zl3073x_dev *zldev, u8 index);
> +int zl3073x_mb_ref_read(struct zl3073x_dev *zldev, u8 index);
> +int zl3073x_mb_ref_write(struct zl3073x_dev *zldev, u8 index);
> +int zl3073x_mb_synth_read(struct zl3073x_dev *zldev, u8 index);
> +int zl3073x_mb_synth_write(struct zl3073x_dev *zldev, u8 index);

I assume these are the only valid ways to access a mailbox?

If so:

> +static inline __maybe_unused int
> +zl3073x_mb_read_ref_mb_mask(struct zl3073x_dev *zldev, u16 *value)
> +{
> + __be16 temp;
> + int rc;
> +
> + lockdep_assert_held(&zldev->mailbox_lock);
> + rc = regmap_bulk_read(zldev->regmap, ZL_REG_REF_MB_MASK, &temp,
> + sizeof(temp));
> + if (rc)
> + return rc;
> +
> + *value = be16_to_cpu(temp);
> + return rc;
> +}

These helpers can be made local to the core. You can then drop the
lockdep_assert_held() from here, since the only way to access them is
via the API you defined above, and add the checks in those API
functions.

Andrew