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Date: Tue, 21 May 2024 14:26:11 +0200
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Subject: Re: [PATCH v3 3/4] mmc: sdhci-brcmstb: Add BCM2712 support
To: Andrea della Porta <andrea.porta@suse.com>, Rob Herring
 <robh@kernel.org>, Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
 Conor Dooley <conor+dt@kernel.org>,
 Florian Fainelli <florian.fainelli@broadcom.com>, Ray Jui
 <rjui@broadcom.com>, Scott Branden <sbranden@broadcom.com>,
 Marc Zyngier <maz@kernel.org>,
 Broadcom internal kernel review list
 <bcm-kernel-feedback-list@broadcom.com>, Ulf Hansson
 <ulf.hansson@linaro.org>, Adrian Hunter <adrian.hunter@intel.com>,
 Kamal Dasu <kamal.dasu@broadcom.com>, Al Cooper <alcooperx@gmail.com>,
 devicetree@vger.kernel.org, linux-rpi-kernel@lists.infradead.org,
 linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
 linux-mmc@vger.kernel.org
References: <cover.1716277695.git.andrea.porta@suse.com>
 <c413737f538d9bd403c30104a83a7fbb1ea7461d.1716277695.git.andrea.porta@suse.com>
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From: Stefan Wahren <wahrenst@gmx.net>
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Hi Andrea,

Am 21.05.24 um 10:35 schrieb Andrea della Porta:
> Broadcom BCM2712 SoC has an SDHCI card controller using the SDIO CFG
> register block present on other STB chips. Add support for BCM2712
> SD capabilities of this chipset.
> The silicon is SD Express capable but this driver port does not currentl=
y
> include that feature yet.
> Based on downstream driver by raspberry foundation maintained kernel.
>
> Signed-off-by: Andrea della Porta <andrea.porta@suse.com>
> ---
>   drivers/mmc/host/sdhci-brcmstb.c | 65 ++++++++++++++++++++++++++++++++
>   1 file changed, 65 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-brcmstb.c b/drivers/mmc/host/sdhci-b=
rcmstb.c
> index 9053526fa212..b349262da36e 100644
> --- a/drivers/mmc/host/sdhci-brcmstb.c
> +++ b/drivers/mmc/host/sdhci-brcmstb.c
> @@ -30,6 +30,21 @@
>
>   #define SDHCI_ARASAN_CQE_BASE_ADDR		0x200
>
> +#define SDIO_CFG_CQ_CAPABILITY			0x4c
> +#define SDIO_CFG_CQ_CAPABILITY_FMUL		GENMASK(13, 12)
> +
> +#define SDIO_CFG_CTRL				0x0
> +#define SDIO_CFG_CTRL_SDCD_N_TEST_EN		BIT(31)
> +#define SDIO_CFG_CTRL_SDCD_N_TEST_LEV		BIT(30)
> +
> +#define SDIO_CFG_MAX_50MHZ_MODE			0x1ac
> +#define SDIO_CFG_MAX_50MHZ_MODE_STRAP_OVERRIDE	BIT(31)
> +#define SDIO_CFG_MAX_50MHZ_MODE_ENABLE		BIT(0)
> +
> +#define MMC_CAP_HSE_MASK	(MMC_CAP2_HSX00_1_2V | MMC_CAP2_HSX00_1_8V)
> +/* Select all SD UHS type I SDR speed above 50MB/s */
> +#define MMC_CAP_UHS_I_SDR_MASK	(MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR104)
> +
>   struct sdhci_brcmstb_priv {
>   	void __iomem *cfg_regs;
>   	unsigned int flags;
> @@ -38,6 +53,7 @@ struct sdhci_brcmstb_priv {
>   };
>
>   struct brcmstb_match_priv {
> +	void (*cfginit)(struct sdhci_host *host);
>   	void (*hs400es)(struct mmc_host *mmc, struct mmc_ios *ios);
>   	struct sdhci_ops *ops;
>   	const unsigned int flags;
> @@ -168,6 +184,38 @@ static void sdhci_brcmstb_set_uhs_signaling(struct =
sdhci_host *host,
>   	sdhci_writew(host, ctrl_2, SDHCI_HOST_CONTROL2);
>   }
>
> +static void sdhci_brcmstb_cfginit_2712(struct sdhci_host *host)
> +{
> +	struct sdhci_pltfm_host *pltfm_host =3D sdhci_priv(host);
> +	struct sdhci_brcmstb_priv *brcmstb_priv =3D sdhci_pltfm_priv(pltfm_hos=
t);
> +	u32 reg, base_clk_mhz;
> +
> +	/*
> +	 * If we support a speed that requires tuning,
> +	 * then select the delay line PHY as the clock source.
> +	 */
> +	if ((host->mmc->caps & MMC_CAP_UHS_I_SDR_MASK) || (host->mmc->caps2 & =
MMC_CAP_HSE_MASK)) {
> +		reg =3D readl(brcmstb_priv->cfg_regs + SDIO_CFG_MAX_50MHZ_MODE);
> +		reg &=3D ~SDIO_CFG_MAX_50MHZ_MODE_ENABLE;
> +		reg |=3D SDIO_CFG_MAX_50MHZ_MODE_STRAP_OVERRIDE;
> +		writel(reg, brcmstb_priv->cfg_regs + SDIO_CFG_MAX_50MHZ_MODE);
> +	}
> +
> +	if ((host->mmc->caps & MMC_CAP_NONREMOVABLE) ||
> +	    (host->mmc->caps & MMC_CAP_NEEDS_POLL)) {
> +		/* Force presence */
> +		reg =3D readl(brcmstb_priv->cfg_regs + SDIO_CFG_CTRL);
> +		reg &=3D ~SDIO_CFG_CTRL_SDCD_N_TEST_LEV;
> +		reg |=3D SDIO_CFG_CTRL_SDCD_N_TEST_EN;
> +		writel(reg, brcmstb_priv->cfg_regs + SDIO_CFG_CTRL);
> +	}
> +
> +	/* Guesstimate the timer frequency (controller base clock) */
> +	base_clk_mhz =3D max_t(u32, clk_get_rate(pltfm_host->clk) / (1000 * 10=
00), 1);
> +	reg =3D SDIO_CFG_CQ_CAPABILITY_FMUL | base_clk_mhz;
> +	writel(reg, brcmstb_priv->cfg_regs + SDIO_CFG_CQ_CAPABILITY);
This part assumes the clock isn't changed afterwards, see below ...
> +}
> +
>   static void sdhci_brcmstb_dumpregs(struct mmc_host *mmc)
>   {
>   	sdhci_dumpregs(mmc_priv(mmc));
> @@ -200,6 +248,14 @@ static struct sdhci_ops sdhci_brcmstb_ops =3D {
>   	.set_uhs_signaling =3D sdhci_set_uhs_signaling,
>   };
>
> +static struct sdhci_ops sdhci_brcmstb_ops_2712 =3D {
> +	.set_clock =3D sdhci_set_clock,
> +	.set_power =3D sdhci_set_power_and_bus_voltage,
> +	.set_bus_width =3D sdhci_set_bus_width,
> +	.reset =3D sdhci_reset,
> +	.set_uhs_signaling =3D sdhci_set_uhs_signaling,
> +};
> +
>   static struct sdhci_ops sdhci_brcmstb_ops_7216 =3D {
>   	.set_clock =3D sdhci_brcmstb_set_clock,
>   	.set_bus_width =3D sdhci_set_bus_width,
> @@ -214,6 +270,11 @@ static struct sdhci_ops sdhci_brcmstb_ops_74165b0 =
=3D {
>   	.set_uhs_signaling =3D sdhci_brcmstb_set_uhs_signaling,
>   };
>
> +static const struct brcmstb_match_priv match_priv_2712 =3D {
> +	.cfginit =3D sdhci_brcmstb_cfginit_2712,
> +	.ops =3D &sdhci_brcmstb_ops_2712,
> +};
> +
>   static struct brcmstb_match_priv match_priv_7425 =3D {
>   	.flags =3D BRCMSTB_MATCH_FLAGS_NO_64BIT |
>   	BRCMSTB_MATCH_FLAGS_BROKEN_TIMEOUT,
> @@ -238,6 +299,7 @@ static struct brcmstb_match_priv match_priv_74165b0 =
=3D {
>   };
>
>   static const struct of_device_id __maybe_unused sdhci_brcm_of_match[] =
=3D {
> +	{ .compatible =3D "brcm,bcm2712-sdhci", .data =3D &match_priv_2712 },
>   	{ .compatible =3D "brcm,bcm7425-sdhci", .data =3D &match_priv_7425 },
>   	{ .compatible =3D "brcm,bcm7445-sdhci", .data =3D &match_priv_7445 },
>   	{ .compatible =3D "brcm,bcm7216-sdhci", .data =3D &match_priv_7216 },
> @@ -370,6 +432,9 @@ static int sdhci_brcmstb_probe(struct platform_devic=
e *pdev)
>   	    (host->mmc->caps2 & MMC_CAP2_HS400_ES))
>   		host->mmc_host_ops.hs400_enhanced_strobe =3D match_priv->hs400es;
>
> +	if (match_priv->cfginit)
> +		match_priv->cfginit(host);
> +
I'm not sure this is the right place to call cfginit.
sdhci_brcmstb_cfginit_2712 retrives the current controller base clock,
but at the end of=C2=A0 sdhci_brcmstb_probe this clock frequency could be
adjusted by the device property "clock-frequency". So i'm not sure this
is intended.
>   	/*
>   	 * Supply the existing CAPS, but clear the UHS modes. This
>   	 * will allow these modes to be specified by device tree