Re: [PATCH v3 3/5] soc: fsl: guts: add the RCW override of any RCWSR

[Frank Li <Frank.li@oss.nxp.com>]

On Sun, Nov 08, 2026 at 11:06:51AM +0100, Vincent Jardin via B4 Relay wrote:
> From: Vincent Jardin <vjardin@free.fr>
>
> fsl_guts_rcw_rmw() only serves the SerDes lane modes. Export it for
> other fields of the RCW:
>  - fsl_guts_rcw_read() reads a status register
>  - fsl_guts_rcw_override() changes fields of one under rcwcr_lock and
>    waits for the status register to follow
>  - fsl_guts_rcw_override_supported() tells whether the DCSR view of DCFG,
>    which holds the override registers, is mapped
>
> Signed-off-by: Vincent Jardin <vjardin@free.fr>
> ---

Reviewed-by: Frank Li <Frank.Li@nxp.com>

>  drivers/soc/fsl/guts.c   | 73 ++++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/fsl/guts.h |  3 ++
>  2 files changed, 76 insertions(+)
>
> diff --git a/drivers/soc/fsl/guts.c b/drivers/soc/fsl/guts.c
> index 28361c63e26c..d2e3f66d0da4 100644
> --- a/drivers/soc/fsl/guts.c
> +++ b/drivers/soc/fsl/guts.c
> @@ -369,6 +369,79 @@ int fsl_guts_lane_set_mode(int serdes_idx, int lane, enum lynx_lane_mode lane_mo
>  }
>  EXPORT_SYMBOL_NS_GPL(fsl_guts_lane_set_mode, "FSL_GUTS");
>
> +/**
> + * fsl_guts_rcw_read() - read a RCW status register
> + * @index: one-based index, RCWSR1 to RCWSR32
> + * @val: the value read
> + *
> + * Return: 0 on success, -ENODEV before the DCFG block is mapped,
> + * -EINVAL when @index is not 1 to 32
> + */
> +int fsl_guts_rcw_read(unsigned int index, u32 *val)
> +{
> +	if (!soc.dcfg_ccsr)
> +		return -ENODEV;
> +	if (index < 1 || index > ARRAY_SIZE(soc.dcfg_ccsr->rcwsr))
> +		return -EINVAL;
> +
> +	*val = fsl_guts_read(&soc.dcfg_ccsr->rcwsr[index - 1]);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_NS_GPL(fsl_guts_rcw_read, "FSL_GUTS");
> +
> +/**
> + * fsl_guts_rcw_override() - override fields of a RCW
> + * @index: one-based index of the RCWSR and RCWCR pair
> + * @val: the new value of the fields, in place
> + * @mask: the fields to change
> + *
> + * The fields outside @mask keep the value the status register shows. The
> + * override register is written and the status register polled until it
> + * shows the result, as fsl_guts_lane_set_mode() does for a SerDes lane.
> + *
> + * Context: takes rcwcr_lock, shared with fsl_guts_lane_set_mode(), and
> + * busy-polls the status register for up to RCW_TIMEOUT_US. Does not
> + * sleep; must not be called from interrupt context.
> + *
> + * Return: 0 on success, -EOPNOTSUPP without a DCSR mapping of DCFG,
> + * negative error otherwise
> + */
> +int fsl_guts_rcw_override(unsigned int index, u32 val, u32 mask)
> +{
> +	int err;
> +
> +	if (!soc.dcfg_ccsr)
> +		return -ENODEV;
> +	if (!soc.dcfg_dcsr)
> +		return -EOPNOTSUPP;
> +	if (index < 1 || index > ARRAY_SIZE(soc.dcfg_ccsr->rcwsr))
> +		return -EINVAL;
> +
> +	spin_lock(&soc.rcwcr_lock);
> +	err = fsl_guts_rcw_rmw(index - 1, val & mask, mask);
> +	spin_unlock(&soc.rcwcr_lock);
> +	if (err)
> +		pr_err("RCW override of RCWSR%u failed: %pe\n", index,
> +		       ERR_PTR(err));
> +
> +	return err;
> +}
> +EXPORT_SYMBOL_NS_GPL(fsl_guts_rcw_override, "FSL_GUTS");
> +
> +/**
> + * fsl_guts_rcw_override_supported() - can a Reset Configuration Word be
> + *				       overridden?
> + *
> + * Return: true when the DCFG block is mapped with its DCSR view, the
> + * second reg of the dcfg node, which holds the override registers
> + */
> +bool fsl_guts_rcw_override_supported(void)
> +{
> +	return soc.dcfg_ccsr && soc.dcfg_dcsr;
> +}
> +EXPORT_SYMBOL_NS_GPL(fsl_guts_rcw_override_supported, "FSL_GUTS");
> +
>  static u64 fsl_guts_get_soc_uid(const char *compat, unsigned int offset)
>  {
>  	struct device_node *np;
> diff --git a/include/linux/fsl/guts.h b/include/linux/fsl/guts.h
> index 8d5ffb985fee..7127de897c23 100644
> --- a/include/linux/fsl/guts.h
> +++ b/include/linux/fsl/guts.h
> @@ -142,6 +142,9 @@ int fsl_guts_lane_validate(int serdes_idx, int lane,
>  			   enum lynx_lane_mode lane_mode);
>  int fsl_guts_lane_set_mode(int serdes_idx, int lane,
>  			   enum lynx_lane_mode lane_mode);
> +int fsl_guts_rcw_read(unsigned int index, u32 *val);
> +int fsl_guts_rcw_override(unsigned int index, u32 val, u32 mask);
> +bool fsl_guts_rcw_override_supported(void);
>
>  /* Alternate function signal multiplex control */
>  #define MPC85xx_PMUXCR_QE(x) (0x8000 >> (x))
>
> --
> 2.43.0
>
>
>