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From:   Jernej =?utf-8?B?xaBrcmFiZWM=?= <jernej.skrabec@gmail.com>
To:     Chen-Yu Tsai <wens@csie.org>,
        Alessandro Zummo <a.zummo@towertech.it>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Samuel Holland <samuel@sholland.org>
Cc:     Samuel Holland <samuel@sholland.org>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-rtc@vger.kernel.org, linux-sunxi@lists.linux.dev
Subject: Re: [PATCH] rtc: sun6i: Add NVMEM provider
Date:   Fri, 15 Apr 2022 20:26:43 +0200
Message-ID: <10062096.nUPlyArG6x@jernej-laptop>
In-Reply-To: <20220413231731.56709-1-samuel@sholland.org>
References: <20220413231731.56709-1-samuel@sholland.org>
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Dne =C4=8Detrtek, 14. april 2022 ob 01:17:30 CEST je Samuel Holland napisal=
(a):
> The sun6i RTC provides 32 bytes of general-purpose data registers.
> They can be used to save data in the always-on RTC power domain.
> The registers are writable via 32-bit MMIO accesses only.
>=20
> Expose them with a NVMEM provider so they can be used by other drivers.
>=20
> Signed-off-by: Samuel Holland <samuel@sholland.org>

Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>

Best regards,
Jernej

> ---
>=20
>  drivers/rtc/rtc-sun6i.c | 42 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
>=20
> diff --git a/drivers/rtc/rtc-sun6i.c b/drivers/rtc/rtc-sun6i.c
> index 5b3e4da63406..755aeb82a285 100644
> --- a/drivers/rtc/rtc-sun6i.c
> +++ b/drivers/rtc/rtc-sun6i.c
> @@ -71,6 +71,10 @@
>  #define SUN6I_LOSC_OUT_GATING			0x0060
>  #define SUN6I_LOSC_OUT_GATING_EN_OFFSET		0
>=20
> +/* General-purpose data */
> +#define SUN6I_GP_DATA				0x0100
> +#define SUN6I_GP_DATA_SIZE			0x20
> +
>  /*
>   * Get date values
>   */
> @@ -662,6 +666,39 @@ static const struct rtc_class_ops sun6i_rtc_ops =3D {
>  	.alarm_irq_enable	=3D sun6i_rtc_alarm_irq_enable
>  };
>=20
> +static int sun6i_rtc_nvmem_read(void *priv, unsigned int offset, void
> *_val, size_t bytes) +{
> +	struct sun6i_rtc_dev *chip =3D priv;
> +	u32 *val =3D _val;
> +	int i;
> +
> +	for (i =3D 0; i < bytes / 4; ++i)
> +		val[i] =3D readl(chip->base + SUN6I_GP_DATA + offset + 4 *=20
i);
> +
> +	return 0;
> +}
> +
> +static int sun6i_rtc_nvmem_write(void *priv, unsigned int offset, void
> *_val, size_t bytes) +{
> +	struct sun6i_rtc_dev *chip =3D priv;
> +	u32 *val =3D _val;
> +	int i;
> +
> +	for (i =3D 0; i < bytes / 4; ++i)
> +		writel(val[i], chip->base + SUN6I_GP_DATA + offset + 4 *=20
i);
> +
> +	return 0;
> +}
> +
> +static struct nvmem_config sun6i_rtc_nvmem_cfg =3D {
> +	.type		=3D NVMEM_TYPE_BATTERY_BACKED,
> +	.reg_read	=3D sun6i_rtc_nvmem_read,
> +	.reg_write	=3D sun6i_rtc_nvmem_write,
> +	.size		=3D SUN6I_GP_DATA_SIZE,
> +	.word_size	=3D 4,
> +	.stride		=3D 4,
> +};
> +
>  #ifdef CONFIG_PM_SLEEP
>  /* Enable IRQ wake on suspend, to wake up from RTC. */
>  static int sun6i_rtc_suspend(struct device *dev)
> @@ -795,6 +832,11 @@ static int sun6i_rtc_probe(struct platform_device
> *pdev) if (ret)
>  		return ret;
>=20
> +	sun6i_rtc_nvmem_cfg.priv =3D chip;
> +	ret =3D devm_rtc_nvmem_register(chip->rtc, &sun6i_rtc_nvmem_cfg);
> +	if (ret)
> +		return ret;
> +
>  	dev_info(&pdev->dev, "RTC enabled\n");
>=20
>  	return 0;