[PATCH v6 3/4] rtc: nvvrs: add NVIDIA VRS RTC device driver

[Alexandre Belloni]

On 19/09/2025 14:02:29+0000, Shubhi Garg wrote:
> +static int nvvrs_rtc_enable_alarm(struct nvvrs_rtc_info *info)
> +{
> +	int ret;
> +
> +	/* Set RTC_WAKE bit for autonomous wake from sleep */
> +	ret = nvvrs_update_bits(info, NVVRS_REG_CTL_2, NVVRS_REG_CTL_2_RTC_WAKE,
> +				NVVRS_REG_CTL_2_RTC_WAKE);
> +	if (ret < 0) {
> +		dev_err(info->dev, "Failed to set RTC_WAKE bit (%d)\n", ret);

This should be either a dev_dbg or removed

> +		return ret;
> +	}
> +
> +	/* Set RTC_PU bit for autonomous wake from shutdown */
> +	ret = nvvrs_update_bits(info, NVVRS_REG_CTL_2, NVVRS_REG_CTL_2_RTC_PU,
> +				NVVRS_REG_CTL_2_RTC_PU);
> +	if (ret < 0) {
> +		dev_err(info->dev, "Failed to set RTC_PU bit (%d)\n", ret);

Ditto

> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int nvvrs_rtc_disable_alarm(struct nvvrs_rtc_info *info)
> +{
> +	struct i2c_client *client = info->client;
> +	u8 val[4];
> +	int ret;
> +
> +	/* Clear RTC_WAKE bit */
> +	ret = nvvrs_update_bits(info, NVVRS_REG_CTL_2, NVVRS_REG_CTL_2_RTC_WAKE,
> +				0);
> +	if (ret < 0) {
> +		dev_err(info->dev, "Failed to clear RTC_WAKE bit (%d)\n", ret);

Ditto

> +		return ret;
> +	}
> +
> +	/* Clear RTC_PU bit */
> +	ret = nvvrs_update_bits(info, NVVRS_REG_CTL_2, NVVRS_REG_CTL_2_RTC_PU,
> +				0);
> +	if (ret < 0) {
> +		dev_err(info->dev, "Failed to clear RTC_PU bit (%d)\n", ret);

Ditto

> +		return ret;
> +	}
> +
> +	/* Write ALARM_RESET_VAL in RTC Alarm register to disable alarm */
> +	val[0] = 0xff;
> +	val[1] = 0xff;
> +	val[2] = 0xff;
> +	val[3] = 0xff;
> +
> +	ret = nvvrs_rtc_write_alarm(client, val);
> +	if (ret < 0)
> +		dev_err(info->dev, "Failed to disable Alarm (%d)\n", ret);

Ditto

> +
> +	return 0;

Plus it fails but then returns 0

> +}
> +
> +static int nvvrs_rtc_read_time(struct device *dev, struct rtc_time *tm)
> +{
> +	struct nvvrs_rtc_info *info = dev_get_drvdata(dev);
> +	time64_t secs = 0;
> +	int ret;
> +	u8 val;
> +
> +	mutex_lock(&info->lock);

This lock is unnecessary once you use rtc_lock/rtc_unlock in the IRQ
handler.

> +
> +	/*
> +	 * Multi-byte transfers are not supported with PEC enabled
> +	 * Read MSB first to avoid coherency issues
> +	 */
> +	ret = i2c_smbus_read_byte_data(info->client, NVVRS_REG_RTC_T3);
> +	if (ret < 0)
> +		goto out;
> +
> +	val = (u8)ret;
> +	secs |= (time64_t)val << 24;
> +
> +	ret = i2c_smbus_read_byte_data(info->client, NVVRS_REG_RTC_T2);
> +	if (ret < 0)
> +		goto out;
> +
> +	val = (u8)ret;
> +	secs |= (time64_t)val << 16;
> +
> +	ret = i2c_smbus_read_byte_data(info->client, NVVRS_REG_RTC_T1);
> +	if (ret < 0)
> +		goto out;
> +
> +	val = (u8)ret;
> +	secs |= (time64_t)val << 8;
> +
> +	ret = i2c_smbus_read_byte_data(info->client, NVVRS_REG_RTC_T0);
> +	if (ret < 0)
> +		goto out;
> +
> +	val = (u8)ret;
> +	secs |= val;
> +
> +	rtc_time64_to_tm(secs, tm);
> +	ret = 0;
> +out:
> +	mutex_unlock(&info->lock);
> +	return ret;
> +}
> +
> +static int nvvrs_rtc_set_time(struct device *dev, struct rtc_time *tm)
> +{
> +	struct nvvrs_rtc_info *info = dev_get_drvdata(dev);
> +	time64_t secs;
> +	u8 time[4];
> +	int ret;
> +
> +	mutex_lock(&info->lock);

Ditto

> +
> +	secs = rtc_tm_to_time64(tm);
> +	time[0] = secs & 0xff;
> +	time[1] = (secs >> 8) & 0xff;
> +	time[2] = (secs >> 16) & 0xff;
> +	time[3] = (secs >> 24) & 0xff;
> +
> +	ret = i2c_smbus_write_byte_data(info->client, NVVRS_REG_RTC_T3, time[3]);
> +	if (ret < 0)
> +		goto out;
> +
> +	ret = i2c_smbus_write_byte_data(info->client, NVVRS_REG_RTC_T2, time[2]);
> +	if (ret < 0)
> +		goto out;
> +
> +	ret = i2c_smbus_write_byte_data(info->client, NVVRS_REG_RTC_T1, time[1]);
> +	if (ret < 0)
> +		goto out;
> +
> +	ret = i2c_smbus_write_byte_data(info->client, NVVRS_REG_RTC_T0, time[0]);
> +out:
> +	mutex_unlock(&info->lock);
> +	return ret;
> +}
> +
> +static int nvvrs_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
> +{
> +	struct nvvrs_rtc_info *info = dev_get_drvdata(dev);
> +	time64_t alarm_val = 0;
> +	int ret;
> +	u8 val;
> +
> +	mutex_lock(&info->lock);

Ditto

> +
> +	/* Multi-byte transfers are not supported with PEC enabled */
> +	ret = i2c_smbus_read_byte_data(info->client, NVVRS_REG_RTC_A3);
> +	if (ret < 0)
> +		goto out;
> +
> +	val = (u8)ret;
> +	alarm_val |= (time64_t)val << 24;
> +
> +	ret = i2c_smbus_read_byte_data(info->client, NVVRS_REG_RTC_A2);
> +	if (ret < 0)
> +		goto out;
> +
> +	val = (u8)ret;
> +	alarm_val |= (time64_t)val << 16;
> +
> +	ret = i2c_smbus_read_byte_data(info->client, NVVRS_REG_RTC_A1);
> +	if (ret < 0)
> +		goto out;
> +
> +	val = (u8)ret;
> +	alarm_val |= (time64_t)val << 8;
> +
> +	ret = i2c_smbus_read_byte_data(info->client, NVVRS_REG_RTC_A0);
> +	if (ret < 0)
> +		goto out;
> +
> +	val = (u8)ret;
> +	alarm_val |= val;
> +
> +	if (alarm_val == ALARM_RESET_VAL)
> +		alrm->enabled = 0;
> +	else
> +		alrm->enabled = 1;
> +
> +	rtc_time64_to_tm(alarm_val, &alrm->time);
> +	ret = 0;
> +out:
> +	mutex_unlock(&info->lock);
> +	return ret;
> +}
> +
> +static int nvvrs_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
> +{
> +	struct nvvrs_rtc_info *info = dev_get_drvdata(dev);
> +	time64_t secs;
> +	u8 time[4];
> +	int ret;
> +
> +	mutex_lock(&info->lock);
> +

Ditto

> +	if (!alrm->enabled) {
> +		ret = nvvrs_rtc_disable_alarm(info);
> +		if (ret < 0)
> +			goto out;
> +	}
> +
> +	ret = nvvrs_rtc_enable_alarm(info);
> +	if (ret < 0)
> +		goto out;
> +
> +	secs = rtc_tm_to_time64(&alrm->time);
> +	time[0] = secs & 0xff;
> +	time[1] = (secs >> 8) & 0xff;
> +	time[2] = (secs >> 16) & 0xff;
> +	time[3] = (secs >> 24) & 0xff;
> +
> +	ret = nvvrs_rtc_write_alarm(info->client, time);
> +
> +out:
> +	mutex_unlock(&info->lock);
> +	return ret;
> +}
> +
> +static int nvvrs_pseq_irq_clear(struct nvvrs_rtc_info *info)
> +{
> +	unsigned int i;
> +	int ret;
> +
> +	for (i = 0; i < NVVRS_IRQ_REG_COUNT; i++) {
> +		ret = i2c_smbus_read_byte_data(info->client,
> +					       NVVRS_REG_INT_SRC1 + i);
> +		if (ret < 0) {
> +			dev_err(info->dev, "Failed to read INT_SRC%d : %d\n",
> +				i + 1, ret);
> +			return ret;
> +		}
> +
> +		ret = i2c_smbus_write_byte_data(info->client,
> +						NVVRS_REG_INT_SRC1 + i,
> +						(u8)ret);
> +		if (ret < 0) {
> +			dev_err(info->dev, "Failed to clear INT_SRC%d : %d\n",
> +				i + 1, ret);
> +			return ret;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static irqreturn_t nvvrs_rtc_irq_handler(int irq, void *data)
> +{
> +	struct nvvrs_rtc_info *info = data;
> +	int ret;
> +
> +	/* Check for RTC alarm interrupt */
> +	ret = i2c_smbus_read_byte_data(info->client, NVVRS_REG_INT_SRC1);
> +	if (ret < 0) {
> +		dev_err(info->dev, "Failed to read INT_SRC1: %d\n", ret);

dev_dbg or remove

> +		return IRQ_NONE;
> +	}
> +
> +	if (ret & NVVRS_INT_SRC1_RTC_MASK) {
> +		rtc_lock(info->rtc);
> +		rtc_update_irq(info->rtc, 1, RTC_IRQF | RTC_AF);
> +		rtc_unlock(info->rtc);
> +	}
> +
> +	/* Clear all interrupts */
> +	if (nvvrs_pseq_irq_clear(info) < 0)
> +		return IRQ_NONE;
> +
> +	return IRQ_HANDLED;
> +}
> +


> diff --git a/include/linux/rtc/rtc-nvidia-vrs10.h b/include/linux/rtc/rtc-nvidia-vrs10.h
> new file mode 100644
> index 000000000000..3c9c46abf555
> --- /dev/null
> +++ b/include/linux/rtc/rtc-nvidia-vrs10.h

Just to be sure, do you expect to use this include in another driver?
Else you should merge it back in the c file.


-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com