linux-kernel - Re: [PATCH 3/3] memory: brcmstb

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Message-ID: <fd349801-0ca1-7f89-f110-513a2cd4fc0f@linaro.org>
Date:   Mon, 27 Mar 2023 18:04:13 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Florian Fainelli <f.fainelli@...il.com>,
        linux-kernel@...r.kernel.org
Cc:     Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@...adcom.com>,
        "moderated list:BROADCOM BCM7XXX ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 3/3] memory: brcmstb_memc: Add new DDR attributes

On 24/03/2023 17:52, Florian Fainelli wrote:
> Provide information about the DDR size, type, width, total width,
> dual/single rank. This is useful for reporting purposes and inventory of
> the system(s).
> 
> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
> ---
>  drivers/memory/brcmstb_memc.c | 80 ++++++++++++++++++++++++++++++++++-
>  1 file changed, 79 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/memory/brcmstb_memc.c b/drivers/memory/brcmstb_memc.c
> index 67c75e21c95e..032567dfd6e2 100644
> --- a/drivers/memory/brcmstb_memc.c
> +++ b/drivers/memory/brcmstb_memc.c
> @@ -13,7 +13,14 @@
>  
>  #define REG_MEMC_CNTRLR_CONFIG		0x00
>  #define  CNTRLR_CONFIG_LPDDR4_SHIFT	5
> -#define  CNTRLR_CONFIG_MASK		0xf
> +#define  CNTRLR_CONFIG_MASK		GENMASK(3, 0)
> +#define  CNTRLR_CONFIG_SIZE_SHIFT	4
> +#define  CNTRLR_CONFIG_SIZE_MASK	GENMASK(7, 4)
> +#define  CNTRLR_CONFIG_WIDTH_SHIFT	8
> +#define  CNTRLR_CONFIG_WIDTH_MASK	GENMASK(9, 8)
> +#define  CNTRLR_CONFIG_TOT_WIDTH_SHIFT	10
> +#define  CNTRLR_CONFIG_TOT_WIDTH_MASK	GENMASK(11, 10)
> +#define  CNTRLR_CONFIG_RANK_SHIFT	16
>  #define REG_MEMC_SRPD_CFG_21		0x20
>  #define REG_MEMC_SRPD_CFG_20		0x34
>  #define REG_MEMC_SRPD_CFG_1x		0x3c
> @@ -63,6 +70,67 @@ static int brcmstb_memc_srpd_config(struct brcmstb_memc *memc,
>  	return 0;
>  }
>  
> +static ssize_t ddr_rank_show(struct device *dev,
> +			     struct device_attribute *attr, char *buf)
> +{
> +	struct brcmstb_memc *memc = dev_get_drvdata(dev);
> +
> +	return sprintf(buf, "%s\n",
> +		       memc->config_reg & CNTRLR_CONFIG_RANK_SHIFT ?
> +		       "dual" : "single");

Why all these are not sysfs_emit()? I think it is the preferred (safer)
interface.

Best regards,
Krzysztof