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Message-ID: <3185e271-2c0e-4a69-9070-46e53434e57d@axis.com>
Date: Tue, 12 Aug 2025 16:49:29 +0200
From: Anders Sandahl <anders.sandahl@...s.com>
To: Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc: linux-rtc@...r.kernel.org, linux-kernel@...r.kernel.org, kernel@...s.com
Subject: Re: [PATCH] rtc: rx8111: Add NVMEM and timestamp functionality
Friendly PING!
On 6/16/25 16:29, Anders Sandahl wrote:
> Hello,
>
> Please let me know if I need to do something more?
>
> BR Anders
>
> On 4/29/25 15:59, Anders Sandahl wrote:
>> Introduce support for saving a timestamp triggered by an external
>> event via the EVIN pin. After an event detection, the timestamp can be
>> retrieved from timestamp0 in sysfs.
>>
>> Also add a sysfs control timestamp0_write_nvmem to enable the RX8111
>> feature that stores timestamps in NVMEM as a circular buffer.
>>
>> Signed-off-by: Anders Sandahl <anders.sandahl@...s.com>
>> ---
>> The Epson RX8111 device has support for saving a time stamp when a
>> hardware trigger occurs. It also has a register area that can be used
>> as non-volatile memory.
>>
>> Datasheet: https://download.epsondevice.com/td/pdf/app/RX8111CE_en.pdf
>>
>> Timestamp is made available in the same manner as in "rtc-rv3028.c"
>> through sys-fs. NVMEM is made available using the framework functions.
>> ---
>> drivers/rtc/rtc-rx8111.c | 351
>> ++++++++++++++++++++++++++++++++++++++++++++++-
>> 1 file changed, 349 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/rtc/rtc-rx8111.c b/drivers/rtc/rtc-rx8111.c
>> index
>> 8450d9f0b566c63bca04988d892ea4db585ac526..4f428eb98f4858b4c70b3a5709d8204a77d0a1ea
>> 100644
>> --- a/drivers/rtc/rtc-rx8111.c
>> +++ b/drivers/rtc/rtc-rx8111.c
>> @@ -58,7 +58,14 @@
>> #define RX8111_FLAG_XST_BIT BIT(0)
>> #define RX8111_FLAG_VLF_BIT BIT(1)
>> +#define RX8111_REG_TS_RAM_START 0x40 /* Timestamp RAM
>> area start. */
>> +#define RX8111_REG_TS_RAM_END 0x7f /* Timestamp RAM area
>> end. */
>> +
>> +#define RX8111_BIT_EVIN_SETTING_OVW BIT(1) /* Enable overwrite
>> timestamp RAM. */
>> +#define RX8111_BIT_EVIN_SETTING_PU1 BIT(3) /* Pull up select
>> 1. */
>> +
>> #define RX8111_TIME_BUF_SZ (RX8111_REG_YEAR - RX8111_REG_SEC + 1)
>> +#define RX8111_TS_BUF_SZ (RX8111_REG_TS_YEAR - RX8111_REG_TS_SEC + 1)
>> enum rx8111_regfield {
>> /* RX8111_REG_EXT. */
>> @@ -98,6 +105,11 @@ enum rx8111_regfield {
>> /* RX8111_REG_STATUS_MON. */
>> RX8111_REGF_VLOW,
>> + /* RX8111_REG_TS_CTRL1. */
>> + RX8111_REGF_TSRAM,
>> + RX8111_REGF_TSCLR,
>> + RX8111_REGF_EISEL,
>> +
>> /* Sentinel value. */
>> RX8111_REGF_MAX
>> };
>> @@ -134,12 +146,16 @@ static const struct reg_field
>> rx8111_regfields[] = {
>> [RX8111_REGF_CHGEN] = REG_FIELD(RX8111_REG_PWR_SWITCH_CTRL, 7,
>> 7),
>> [RX8111_REGF_VLOW] = REG_FIELD(RX8111_REG_STATUS_MON, 1, 1),
>> +
>> + [RX8111_REGF_TSRAM] = REG_FIELD(RX8111_REG_TS_CTRL1, 0, 0),
>> + [RX8111_REGF_TSCLR] = REG_FIELD(RX8111_REG_TS_CTRL1, 1, 1),
>> + [RX8111_REGF_EISEL] = REG_FIELD(RX8111_REG_TS_CTRL1, 2, 2),
>> };
>> static const struct regmap_config rx8111_regmap_config = {
>> .reg_bits = 8,
>> .val_bits = 8,
>> - .max_register = RX8111_REG_TS_CTRL3,
>> + .max_register = RX8111_REG_TS_RAM_END,
>> };
>> struct rx8111_data {
>> @@ -147,8 +163,224 @@ struct rx8111_data {
>> struct regmap_field *regfields[RX8111_REGF_MAX];
>> struct device *dev;
>> struct rtc_device *rtc;
>> + spinlock_t ts_lock; /* Don't allow poll of ETS bit when it's
>> temporarily disabled. */
>> };
>> +static ssize_t timestamp0_store(struct device *dev,
>> + struct device_attribute *attr, const char *buf,
>> + size_t count)
>> +{
>> + struct rx8111_data *data = dev_get_drvdata(dev);
>> + int ret, etsval;
>> +
>> + /*
>> + * Clear event only if events are enabled. This is to protect
>> + * us from losing events in the future if events have been disabled
>> + * by mistake (error in read function).
>> + */
>> + spin_lock(&data->ts_lock);
>> + ret = regmap_field_read(data->regfields[RX8111_REGF_ETS], &etsval);
>> + spin_unlock(&data->ts_lock);
>> +
>> + if (ret) {
>> + dev_dbg(dev, "Could not read ETS (%d)\n", ret);
>> + return ret;
>> + }
>> +
>> + if (!etsval)
>> + return -EINVAL;
>> +
>> + ret = regmap_field_write(data->regfields[RX8111_REGF_EVF], 0);
>> + if (ret) {
>> + dev_dbg(dev, "Could not write EVF bit (%d)\n", ret);
>> + return ret;
>> + }
>> +
>> + ret = regmap_field_write(data->regfields[RX8111_REGF_TSCLR], 1);
>> + if (ret) {
>> + dev_dbg(dev, "Could not write TSCLR bit (%d)\n", ret);
>> + return ret;
>> + }
>> +
>> + return count;
>> +}
>> +
>> +static ssize_t timestamp0_show(struct device *dev,
>> + struct device_attribute *attr, char *buf)
>> +{
>> + struct rx8111_data *data = dev_get_drvdata(dev);
>> +
>> + struct rtc_time tm;
>> + int ret, evfval;
>> + u8 date[RX8111_TS_BUF_SZ];
>> +
>> + /* Read out timestamp values only when an event has occurred. */
>> + ret = regmap_field_read(data->regfields[RX8111_REGF_EVF], &evfval);
>> + if (ret) {
>> + dev_dbg(dev, "Could not read EVF (%d)\n", ret);
>> + return ret;
>> + }
>> +
>> + if (!evfval)
>> + return 0;
>> +
>> + spin_lock(&data->ts_lock);
>> +
>> + /* Disable timestamp during readout to avoid unreliable data. */
>> + ret = regmap_field_write(data->regfields[RX8111_REGF_ETS], 0);
>> + if (ret) {
>> + dev_dbg(dev, "Could not disable timestamp function (%d)\n",
>> + ret);
>> + goto err_out;
>> + }
>> +
>> + ret = regmap_bulk_read(data->regmap, RX8111_REG_TS_SEC, date,
>> + sizeof(date));
>> + if (ret) {
>> + dev_dbg(dev, "Could not read timestamp data (%d)\n", ret);
>> + goto err_out;
>> + }
>> +
>> + ret = regmap_field_write(data->regfields[RX8111_REGF_ETS], 1);
>> + if (ret) {
>> + dev_dbg(dev, "Could not enable timestamp function (%d)\n",
>> ret);
>> + goto err_out;
>> + }
>> +
>> + spin_unlock(&data->ts_lock);
>> +
>> + tm.tm_sec = bcd2bin(date[0]);
>> + tm.tm_min = bcd2bin(date[1]);
>> + tm.tm_hour = bcd2bin(date[2]);
>> + tm.tm_mday = bcd2bin(date[4]);
>> + tm.tm_mon = bcd2bin(date[5]) - 1;
>> + tm.tm_year = bcd2bin(date[6]) + 100;
>> +
>> + ret = rtc_valid_tm(&tm);
>> + if (ret)
>> + return ret;
>> +
>> + return sprintf(buf, "%llu\n",
>> + (unsigned long long)rtc_tm_to_time64(&tm));
>> +
>> +err_out:
>> + spin_unlock(&data->ts_lock);
>> + return ret;
>> +}
>> +
>> +static DEVICE_ATTR_RW(timestamp0);
>> +
>> +static ssize_t timestamp0_write_nvmem_store(struct device *dev,
>> + struct device_attribute *attr,
>> + const char *buf, size_t count)
>> +{
>> + struct rx8111_data *data = dev_get_drvdata(dev);
>> + bool enable;
>> + int ret;
>> +
>> + if (count < 1)
>> + return -EINVAL;
>> +
>> + ret = kstrtobool(buf, &enable);
>> + if (ret)
>> + return ret;
>> +
>> + ret = regmap_field_write(data->regfields[RX8111_REGF_TSRAM],
>> + enable ? 1 : 0);
>> + if (ret) {
>> + dev_dbg(dev, "Could not set TSRAM bit (%d)\n", ret);
>> + return ret;
>> + }
>> +
>> + return count;
>> +}
>> +
>> +static ssize_t timestamp0_write_nvmem_show(struct device *dev,
>> + struct device_attribute *attr,
>> + char *buf)
>> +{
>> + struct rx8111_data *data = dev_get_drvdata(dev);
>> + int enable;
>> + int ret;
>> +
>> + ret = regmap_field_read(data->regfields[RX8111_REGF_TSRAM],
>> &enable);
>> + if (ret) {
>> + dev_dbg(dev, "Could not read TSRAM bit (%d)\n", ret);
>> + return ret;
>> + }
>> +
>> + return sprintf(buf, "%s\n", enable ? "1" : "0");
>> +}
>> +
>> +static DEVICE_ATTR_RW(timestamp0_write_nvmem);
>> +
>> +static int rx8111_sysfs_register(struct device *dev)
>> +{
>> + int ret;
>> +
>> + ret = device_create_file(dev, &dev_attr_timestamp0);
>> + if (ret)
>> + return ret;
>> +
>> + ret = device_create_file(dev, &dev_attr_timestamp0_write_nvmem);
>> + if (ret)
>> + device_remove_file(dev, &dev_attr_timestamp0);
>> +
>> + return ret;
>> +}
>> +
>> +static void rx8111_sysfs_unregister(void *data)
>> +{
>> + struct device *dev = (struct device *)data;
>> +
>> + device_remove_file(dev, &dev_attr_timestamp0);
>> + device_remove_file(dev, &dev_attr_timestamp0_write_nvmem);
>> +}
>> +
>> +static int rx8111_setup(struct rx8111_data *data)
>> +{
>> + int ret;
>> +
>> + /* Disable multiple timestamps; area is used for nvmem as
>> default. */
>> + ret = regmap_write(data->regmap, RX8111_REG_TS_CTRL2, 0);
>> + if (ret) {
>> + dev_dbg(data->dev, "Could not setup TS_CTRL2 (%d)\n", ret);
>> + return ret;
>> + }
>> +
>> + ret = regmap_write(data->regmap, RX8111_REG_TS_CTRL3, 0);
>> + if (ret) {
>> + dev_dbg(data->dev, "Could not setup TS_CTRL3 (%d)\n", ret);
>> + return ret;
>> + }
>> +
>> + /* Configure EVIN pin, trigger on low level. PU = 1M Ohm. */
>> + ret = regmap_write(data->regmap, RX8111_REG_EVIN_SETTING,
>> + RX8111_BIT_EVIN_SETTING_PU1 |
>> + RX8111_BIT_EVIN_SETTING_OVW);
>> + if (ret) {
>> + dev_dbg(data->dev, "Could not setup EVIN (%d)\n", ret);
>> + return ret;
>> + }
>> +
>> + /* Enable timestamp triggered by EVIN pin. */
>> + ret = regmap_field_write(data->regfields[RX8111_REGF_ETS], 1);
>> + if (ret) {
>> + dev_dbg(data->dev, "Could not enable timestamp function
>> (%d)\n",
>> + ret);
>> + return ret;
>> + }
>> +
>> + /* Disable all interrupts. */
>> + ret = regmap_write(data->regmap, RX8111_REG_CTRL, 0);
>> + if (ret) {
>> + dev_dbg(data->dev, "Could not disable interrupts (%d)\n", ret);
>> + return ret;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> static int rx8111_read_vl_flag(struct rx8111_data *data, unsigned
>> int *vlval)
>> {
>> int ret;
>> @@ -160,6 +392,17 @@ static int rx8111_read_vl_flag(struct
>> rx8111_data *data, unsigned int *vlval)
>> return ret;
>> }
>> +static int rx8111_clear_vl_flag(struct rx8111_data *data)
>> +{
>> + int ret;
>> +
>> + ret = regmap_field_write(data->regfields[RX8111_REGF_VLF], 0);
>> + if (ret)
>> + dev_dbg(data->dev, "Could not write VL flag (%d)", ret);
>> +
>> + return ret;
>> +}
>> +
>> static int rx8111_read_time(struct device *dev, struct rtc_time *tm)
>> {
>> struct rx8111_data *data = dev_get_drvdata(dev);
>> @@ -289,11 +532,69 @@ static int rx8111_ioctl(struct device *dev,
>> unsigned int cmd, unsigned long arg)
>> vlval |= regval ? RTC_VL_BACKUP_LOW : 0;
>> return put_user(vlval, (typeof(vlval) __user *)arg);
>> + case RTC_VL_CLR:
>> + return rx8111_clear_vl_flag(data);
>> default:
>> return -ENOIOCTLCMD;
>> }
>> }
>> +static int rx8111_nvram_write(void *priv, unsigned int offset,
>> void *val,
>> + size_t bytes)
>> +{
>> + struct rx8111_data *data = priv;
>> + int ret, len;
>> +
>> + /*
>> + * The RX8111 device can only handle transfers with repeated start
>> + * within the same 16 bytes aligned block.
>> + */
>> + while (bytes > 0) {
>> + len = ((offset % 15) + bytes > 16) ? 16 - (offset % 16) :
>> bytes;
>> + ret = regmap_bulk_write(data->regmap,
>> + RX8111_REG_TS_RAM_START + offset, val,
>> + len);
>> + if (ret) {
>> + dev_dbg(data->dev, "Could not write nvmem (%d)\n", ret);
>> + return ret;
>> + }
>> +
>> + val += len;
>> + offset += len;
>> + bytes -= len;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int rx8111_nvram_read(void *priv, unsigned int offset, void
>> *val,
>> + size_t bytes)
>> +{
>> + struct rx8111_data *data = priv;
>> + int ret, len;
>> +
>> + /*
>> + * The RX8111 device can only handle transfers with repeated start
>> + * within the same 16 bytes aligned block.
>> + */
>> + while (bytes > 0) {
>> + len = ((offset % 15) + bytes > 16) ? 16 - (offset % 16) :
>> bytes;
>> + ret = regmap_bulk_read(data->regmap,
>> + RX8111_REG_TS_RAM_START + offset, val,
>> + len);
>> + if (ret) {
>> + dev_dbg(data->dev, "Could not read nvmem (%d)\n", ret);
>> + return ret;
>> + }
>> +
>> + val += len;
>> + offset += len;
>> + bytes -= len;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> static const struct rtc_class_ops rx8111_rtc_ops = {
>> .read_time = rx8111_read_time,
>> .set_time = rx8111_set_time,
>> @@ -305,6 +606,16 @@ static int rx8111_probe(struct i2c_client *client)
>> struct rx8111_data *data;
>> struct rtc_device *rtc;
>> size_t i;
>> + int ret;
>> + struct nvmem_config nvmem_cfg = {
>> + .name = "rx8111_nvram",
>> + .word_size = 1,
>> + .stride = 1,
>> + .size = RX8111_REG_TS_RAM_END - RX8111_REG_TS_RAM_START + 1,
>> + .type = NVMEM_TYPE_BATTERY_BACKED,
>> + .reg_read = rx8111_nvram_read,
>> + .reg_write = rx8111_nvram_write,
>> + };
>> data = devm_kmalloc(&client->dev, sizeof(*data), GFP_KERNEL);
>> if (!data) {
>> @@ -312,6 +623,8 @@ static int rx8111_probe(struct i2c_client *client)
>> return -ENOMEM;
>> }
>> + spin_lock_init(&data->ts_lock);
>> +
>> data->dev = &client->dev;
>> dev_set_drvdata(data->dev, data);
>> @@ -331,6 +644,10 @@ static int rx8111_probe(struct i2c_client
>> *client)
>> }
>> }
>> + ret = rx8111_setup(data);
>> + if (ret)
>> + return ret;
>> +
>> rtc = devm_rtc_allocate_device(data->dev);
>> if (IS_ERR(rtc)) {
>> dev_dbg(data->dev, "Could not allocate rtc device\n");
>> @@ -343,7 +660,37 @@ static int rx8111_probe(struct i2c_client *client)
>> clear_bit(RTC_FEATURE_ALARM, rtc->features);
>> - return devm_rtc_register_device(rtc);
>> + ret = devm_rtc_register_device(rtc);
>> + if (ret) {
>> + dev_dbg(data->dev,
>> + "Could not register rtc device (%d)\n", ret);
>> + return ret;
>> + }
>> +
>> + ret = rx8111_sysfs_register(data->dev);
>> + if (ret) {
>> + dev_dbg(data->dev,
>> + "Could not create sysfs entry (%d)\n", ret);
>> + return ret;
>> + }
>> +
>> + ret = devm_add_action_or_reset(data->dev, &rx8111_sysfs_unregister,
>> + data->dev);
>> + if (ret) {
>> + dev_dbg(data->dev,
>> + "Could not add sysfs unregister devres action (%d)\n",
>> ret);
>> + return ret;
>> + }
>> +
>> + nvmem_cfg.priv = data;
>> + ret = devm_rtc_nvmem_register(rtc, &nvmem_cfg);
>> + if (ret) {
>> + dev_dbg(data->dev,
>> + "Could not register rtc nvmem device (%d)\n", ret);
>> + return ret;
>> + }
>> +
>> + return 0;
>> }
>> static const struct of_device_id rx8111_of_match[] = {
>>
>> ---
>> base-commit: 38fec10eb60d687e30c8c6b5420d86e8149f7557
>> change-id: 20250424-rtc-rx8111-events-df9a35810a73
>>
>> Best regards,
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