linux-kernel - Re: [PATCH v4 4/6] mmc: sdhci-cadence: enable MMC_SDHCI_IO

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Message-ID: <dfc72fd8-0b4a-71bc-ee0c-9ad97f8de6dc@intel.com>
Date:   Wed, 26 Jul 2023 15:42:39 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Piyush Malgujar <pmalgujar@...vell.com>, linux-mmc@...r.kernel.org,
        linux-kernel@...r.kernel.org, ulf.hansson@...aro.org,
        p.zabel@...gutronix.de, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        yamada.masahiro@...ionext.com, devicetree@...r.kernel.org
Cc:     jannadurai@...vell.com, cchavva@...vell.com
Subject: Re: [PATCH v4 4/6] mmc: sdhci-cadence: enable MMC_SDHCI_IO_ACCESSORS
 support

On 17/07/23 15:51, Piyush Malgujar wrote:
> From: Jayanthi Annadurai <jannadurai@...vell.com>
> 
> Add support of CONFIG_MMC_SDHCI_IO_ACCESSORS to allow Marvell
> SoC ops for SD6 controller to overwrite the SDHCI IO memory
> accessors.
> 
> Signed-off-by: Jayanthi Annadurai <jannadurai@...vell.com>
> Signed-off-by: Piyush Malgujar <pmalgujar@...vell.com>
> ---
>  drivers/mmc/host/sdhci-cadence.c | 59 ++++++++++++++++++++++++++++++++
>  1 file changed, 59 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-cadence.c b/drivers/mmc/host/sdhci-cadence.c
> index 8bcf585185053b0afaff2625d62316cec1824fa3..f1e597219c603f3921439cedb22dcb2884abe68d 100644
> --- a/drivers/mmc/host/sdhci-cadence.c
> +++ b/drivers/mmc/host/sdhci-cadence.c
> @@ -448,6 +448,59 @@ static u32 read_dqs_cmd_delay, clk_wrdqs_delay, clk_wr_delay, read_dqs_delay;
>  
>  static u32 sdhci_cdns_sd6_get_mode(struct sdhci_host *host, unsigned int timing);
>  
> +static u32 sdhci_cdns_sd6_readl(struct sdhci_host *host, int reg)
> +{
> +	return readl(host->ioaddr + reg);
> +}

Doesn't need to be implemented if it is the same as the
default behaviour

> +
> +static void sdhci_cdns_sd6_writel(struct sdhci_host *host, u32 val, int reg)
> +{
> +	writel(val, host->ioaddr + reg);
> +}

Doesn't need to be implemented if it is the same as the
default behaviour

> +
> +static u16 sdhci_cdns_sd6_readw(struct sdhci_host *host, int reg)
> +{
> +	u32 val, regoff;
> +
> +	regoff = reg & ~3;
> +
> +	val = readl(host->ioaddr + regoff);
> +	if ((reg & 0x3) == 0)
> +		return (val & 0xFFFF);
> +	else
> +		return ((val >> 16) & 0xFFFF);
> +}

You can use upper_16_bits() etc e.g.

static u16 sdhci_cdns_sd6_readw(struct sdhci_host *host, int reg)
{
	u32 val = readl(host->ioaddr + (reg & ~3));

	return reg & 0x3 ? upper_16_bits(val) : lower_16_bits(val);
}

> +
> +static void sdhci_cdns_sd6_writew(struct sdhci_host *host, u16 val, int reg)
> +{
> +	writew(val, host->ioaddr + reg);
> +}

Doesn't need to be implemented if it is the same as the
default behaviour

> +
> +static u8 sdhci_cdns_sd6_readb(struct sdhci_host *host, int reg)
> +{
> +	u32 val, regoff;
> +
> +	regoff = reg & ~3;
> +
> +	val = readl(host->ioaddr + regoff);
> +	switch (reg & 3) {
> +	case 0:
> +		return (val & 0xFF);
> +	case 1:
> +		return ((val >> 8) & 0xFF);
> +	case 2:
> +		return ((val >> 16) & 0xFF);
> +	case 3:
> +		return ((val >> 24) & 0xFF);
> +	}
> +	return 0;
> +}

Probably could just be:

static u8 sdhci_cdns_sd6_readb(struct sdhci_host *host, int reg)
{
	u32 val = readl(host->ioaddr + (reg & ~3));

	return val >> (8 * (reg & 3)));
}

> +
> +static void sdhci_cdns_sd6_writeb(struct sdhci_host *host, u8 val, int reg)
> +{
> +	writeb(val, host->ioaddr + reg);
> +}

Doesn't need to be implemented if it is the same as the
default behaviour

> +
>  static int sdhci_cdns_sd6_phy_lock_dll(struct sdhci_cdns_sd6_phy *phy)
>  {
>  	u32 delay_element = phy->d.delay_element_org;
> @@ -1666,6 +1719,12 @@ static const struct sdhci_ops sdhci_cdns_sd4_ops = {
>  };
>  
>  static const struct sdhci_ops sdhci_cdns_sd6_ops = {
> +	.read_l = sdhci_cdns_sd6_readl,
> +	.write_l = sdhci_cdns_sd6_writel,
> +	.read_w = sdhci_cdns_sd6_readw,
> +	.write_w = sdhci_cdns_sd6_writew,
> +	.read_b = sdhci_cdns_sd6_readb,
> +	.write_b = sdhci_cdns_sd6_writeb,
>  	.get_max_clock = sdhci_cdns_get_max_clock,
>  	.set_clock = sdhci_cdns_sd6_set_clock,
>  	.get_timeout_clock = sdhci_cdns_get_timeout_clock,