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@xxxxxxxxxxxx>
---
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
