linux-sunxi.lists.linux.dev archive mirror
 help / color / mirror / Atom feed
From: Samuel Holland <samuel@sholland.org>
To: Alessandro Zummo <a.zummo@towertech.it>,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	Maxime Ripard <mripard@kernel.org>, Chen-Yu Tsai <wens@csie.org>,
	Jernej Skrabec <jernej.skrabec@siol.net>
Cc: linux-rtc@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-sunxi@lists.linux.dev, linux-kernel@vger.kernel.org,
	Samuel Holland <samuel@sholland.org>
Subject: [PATCH] rtc: sun6i: Add NVMEM provider
Date: Sun, 18 Apr 2021 20:45:49 -0500	[thread overview]
Message-ID: <20210419014549.26900-1-samuel@sholland.org> (raw)

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 the region as a NVMEM provider so it can be used by userspace and
other drivers.

Signed-off-by: Samuel Holland <samuel@sholland.org>
---
 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 e75020ab8024..f4a5e7465148 100644
--- a/drivers/rtc/rtc-sun6i.c
+++ b/drivers/rtc/rtc-sun6i.c
@@ -69,6 +69,10 @@
 #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
  */
@@ -641,6 +645,39 @@ 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,
+};
+
 /* Enable IRQ wake on suspend, to wake up from RTC. */
 static int sun6i_rtc_suspend(struct device *dev)
 {
@@ -728,6 +765,11 @@ 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;
-- 
2.26.3


             reply	other threads:[~2021-04-19  1:45 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-19  1:45 Samuel Holland [this message]
2021-04-30  9:02 ` Maxime Ripard
2021-05-04 15:33   ` Alexandre Belloni
2021-05-10  3:39   ` Samuel Holland
2021-05-10  8:00     ` Alexandre Belloni
2021-05-25  8:24     ` Maxime Ripard
2021-05-27  4:09       ` Samuel Holland
2022-04-13 23:17 Samuel Holland
2022-04-15 18:26 ` Jernej Škrabec
2022-05-17 20:49 ` alexandre.belloni

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210419014549.26900-1-samuel@sholland.org \
    --to=samuel@sholland.org \
    --cc=a.zummo@towertech.it \
    --cc=alexandre.belloni@bootlin.com \
    --cc=jernej.skrabec@siol.net \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-rtc@vger.kernel.org \
    --cc=linux-sunxi@lists.linux.dev \
    --cc=mripard@kernel.org \
    --cc=wens@csie.org \
    --subject='Re: [PATCH] rtc: sun6i: Add NVMEM provider' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).