linux-kernel - Re: [PATCH v4 01/10] drivers: qcom: rpmh-rsc: Clean code reading/writing TCS regs/cmds

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Date:   Mon, 13 Apr 2020 11:19:46 -0700
From:   Joe Perches <joe@...ches.com>
To:     Douglas Anderson <dianders@...omium.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Maulik Shah <mkshah@...eaurora.org>
Cc:     swboyd@...omium.org, mka@...omium.org,
        Rajendra Nayak <rnayak@...eaurora.org>, evgreen@...omium.org,
        Lina Iyer <ilina@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 01/10] drivers: qcom: rpmh-rsc: Clean code
 reading/writing TCS regs/cmds

On Mon, 2020-04-13 at 10:04 -0700, Douglas Anderson wrote:
> This patch makes two changes, both of which should be no-ops:
> 
> 1. Make read_tcs_reg() / read_tcs_cmd() symmetric to write_tcs_reg() /
>    write_tcs_cmd().
> 
> 2. Change the order of operations in the above functions to make it
>    more obvious to me what the math is doing.  Specifically first you
>    want to find the right TCS, then the right register, and then
>    multiply by the command ID if necessary.

Though these operations are only used a couple times, perhaps
it'd be useful to have static inlines for the calcs.

> diff --git a/drivers/soc/qcom/rpmh-rsc.c b/drivers/soc/qcom/rpmh-rsc.c
[]
> @@ -67,28 +67,33 @@
>  #define CMD_STATUS_ISSUED		BIT(8)
>  #define CMD_STATUS_COMPL		BIT(16)

Maybe something like:

static inline void __iomem *
tcs_reg_addr(struct rsc_drv drv, int reg, int tcs_id)
{
	return drv->tcs_base + RSC_DRV_TCS_OFFSET * tcs_id + reg;
}

static inline void __iomem *
tcs_cmd_addr(struct rsc_drv drv, int reg, int tcs_id, int cmd_id)
{
	return tcs_reg_addr(drv, reg, tcs_id) + RSC_DRV_CMD_OFFSET * cmd_id;
}

> -static u32 read_tcs_reg(struct rsc_drv *drv, int reg, int tcs_id, int cmd_id)
> +static u32 read_tcs_cmd(struct rsc_drv *drv, int reg, int tcs_id, int cmd_id)
>  {
> -	return readl_relaxed(drv->tcs_base + reg + RSC_DRV_TCS_OFFSET * tcs_id +
> +	return readl_relaxed(drv->tcs_base + RSC_DRV_TCS_OFFSET * tcs_id + reg +
>  			     RSC_DRV_CMD_OFFSET * cmd_id);

	return readl_relaxed(tcs_cmd_addr(drv, reg, tcs_id, cmd_id));

etc...