Re: [PATCH v9 11/12] soc: mediatek: cmdq: add cmdq_dev_get_client_reg function

[CK Hu <ck.hu@mediatek.com>]

Hi, Bibby:

On Thu, 2019-06-27 at 14:19 +0800, Bibby Hsieh wrote:
> GCE cannot know the register base address, this function
> can help cmdq client to get the cmdq_client_reg structure.
> 
> Signed-off-by: Bibby Hsieh <bibby.hsieh@mediatek.com>
> ---
>  drivers/soc/mediatek/mtk-cmdq-helper.c | 24 ++++++++++++++++++++++++
>  include/linux/soc/mediatek/mtk-cmdq.h  | 21 +++++++++++++++++++++
>  2 files changed, 45 insertions(+)
> 
> diff --git a/drivers/soc/mediatek/mtk-cmdq-helper.c b/drivers/soc/mediatek/mtk-cmdq-helper.c
> index 70ad4d806fac..ceb1b569891f 100644
> --- a/drivers/soc/mediatek/mtk-cmdq-helper.c
> +++ b/drivers/soc/mediatek/mtk-cmdq-helper.c
> @@ -27,6 +27,30 @@ struct cmdq_instruction {
>  	u8 op;
>  };
>  
> +int cmdq_dev_get_client_reg(struct device *dev,
> +			    struct cmdq_client_reg *client_reg, int idx)
> +{
> +	struct of_phandle_args spec;
> +
> +	if (!client_reg)
> +		return -ENOENT;
> +
> +	if (of_parse_phandle_with_args(dev->of_node, "mediatek,gce-client-reg",
> +				       "#subsys-cells", idx, &spec)) {
> +		dev_err(dev, "can't parse gce-client-reg property (%d)", idx);
> +
> +		return -ENOENT;

Maybe my expression is not so clear. of_parse_phandle_with_args() may
return -ENOENT, but it also may return -EINVAL. My point is why do you
change the return value of of_parse_phandle_with_args(). What the error
you get from of_parse_phandle_with_args(), you could also return it to
the caller of cmdq_dev_get_client_reg().

Regards,
CK

> +	}
> +
> +	client_reg->subsys = spec.args[0];
> +	client_reg->offset = spec.args[1];
> +	client_reg->size = spec.args[2];
> +	of_node_put(spec.np);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(cmdq_dev_get_client_reg);
> +
>  static void cmdq_client_timeout(struct timer_list *t)
>  {
>  	struct cmdq_client *client = from_timer(client, t, timer);
> diff --git a/include/linux/soc/mediatek/mtk-cmdq.h b/include/linux/soc/mediatek/mtk-cmdq.h
> index a345870a6d10..be402c4c740e 100644
> --- a/include/linux/soc/mediatek/mtk-cmdq.h
> +++ b/include/linux/soc/mediatek/mtk-cmdq.h
> @@ -15,6 +15,12 @@
>  
>  struct cmdq_pkt;
>  
> +struct cmdq_client_reg {
> +	u8 subsys;
> +	u16 offset;
> +	u16 size;
> +};
> +
>  struct cmdq_client {
>  	spinlock_t lock;
>  	u32 pkt_cnt;
> @@ -142,4 +148,19 @@ int cmdq_pkt_flush_async(struct cmdq_pkt *pkt, cmdq_async_flush_cb cb,
>   */
>  int cmdq_pkt_flush(struct cmdq_pkt *pkt);
>  
> +/**
> + * cmdq_dev_get_client_reg() - parse cmdq client reg from the device
> + *			       node of CMDQ client
> + * @dev:	device of CMDQ mailbox clienti
> + * @client_reg: CMDQ client reg pointer
> + * @idx:	the index of desired reg
> + *
> + * Return: 0 for success; else the error code is returned
> + *
> + * Help CMDQ client pasing the cmdq client reg
> + * from the device node of CMDQ client.
> + */
> +int cmdq_dev_get_client_reg(struct device *dev,
> +			    struct cmdq_client_reg *client_reg, int idx);
> +
>  #endif	/* __MTK_CMDQ_H__ */