linux-kernel - Re: [PATCH] rtc: sun6i: Add NVMEM provider

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Date:   Fri, 15 Apr 2022 20:26:43 +0200
From:   Jernej Škrabec <jernej.skrabec@...il.com>
To:     Chen-Yu Tsai <wens@...e.org>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Samuel Holland <samuel@...lland.org>
Cc:     Samuel Holland <samuel@...lland.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-rtc@...r.kernel.org, linux-sunxi@...ts.linux.dev
Subject: Re: [PATCH] rtc: sun6i: Add NVMEM provider

Dne četrtek, 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.
> 
> Expose them with a NVMEM provider so they can be used by other drivers.
> 
> Signed-off-by: Samuel Holland <samuel@...lland.org>

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

Best regards,
Jernej

> ---
> 
>  drivers/rtc/rtc-sun6i.c | 42 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
> 
> 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
> 
> +/* 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 = {
>  	.alarm_irq_enable	= sun6i_rtc_alarm_irq_enable
>  };
> 
> +static int sun6i_rtc_nvmem_read(void *priv, unsigned int offset, void
> *_val, size_t bytes) +{
> +	struct sun6i_rtc_dev *chip = priv;
> +	u32 *val = _val;
> +	int i;
> +
> +	for (i = 0; i < bytes / 4; ++i)
> +		val[i] = readl(chip->base + SUN6I_GP_DATA + offset + 4 * 
i);
> +
> +	return 0;
> +}
> +
> +static int sun6i_rtc_nvmem_write(void *priv, unsigned int offset, void
> *_val, size_t bytes) +{
> +	struct sun6i_rtc_dev *chip = priv;
> +	u32 *val = _val;
> +	int i;
> +
> +	for (i = 0; i < bytes / 4; ++i)
> +		writel(val[i], chip->base + SUN6I_GP_DATA + offset + 4 * 
i);
> +
> +	return 0;
> +}
> +
> +static struct nvmem_config sun6i_rtc_nvmem_cfg = {
> +	.type		= NVMEM_TYPE_BATTERY_BACKED,
> +	.reg_read	= sun6i_rtc_nvmem_read,
> +	.reg_write	= sun6i_rtc_nvmem_write,
> +	.size		= SUN6I_GP_DATA_SIZE,
> +	.word_size	= 4,
> +	.stride		= 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;
> 
> +	sun6i_rtc_nvmem_cfg.priv = chip;
> +	ret = devm_rtc_nvmem_register(chip->rtc, &sun6i_rtc_nvmem_cfg);
> +	if (ret)
> +		return ret;
> +
>  	dev_info(&pdev->dev, "RTC enabled\n");
> 
>  	return 0;