[PATCH 2/2] rtc: isl12022: Add alarm support

From: Esben Haabendal
Date: Tue Sep 10 2024 - 06:32:29 EST

The ISL12022 RTC has a combined INT/fOUT pin, which can be used for alarm
interrupt when frequency output is not enabled.

The device-tree bindings should ensure that interrupt and clock output is
not enabled at the same time.

Signed-off-by: Esben Haabendal <esben@xxxxxxxxxx>
---
drivers/rtc/rtc-isl12022.c | 244 ++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 241 insertions(+), 3 deletions(-)

diff --git a/drivers/rtc/rtc-isl12022.c b/drivers/rtc/rtc-isl12022.c
index d82278fdc29b..682b1bf10160 100644
--- a/drivers/rtc/rtc-isl12022.c
+++ b/drivers/rtc/rtc-isl12022.c
@@ -21,7 +21,7 @@

#include <asm/byteorder.h>

-/* ISL register offsets */
+/* RTC - Real time clock registers */
#define ISL12022_REG_SC 0x00
#define ISL12022_REG_MN 0x01
#define ISL12022_REG_HR 0x02
@@ -30,21 +30,36 @@
#define ISL12022_REG_YR 0x05
#define ISL12022_REG_DW 0x06

+/* CSR - Control and status registers */
#define ISL12022_REG_SR 0x07
#define ISL12022_REG_INT 0x08
-
#define ISL12022_REG_PWR_VBAT 0x0a
-
#define ISL12022_REG_BETA 0x0d
+
+/* ALARM - Alarm registers */
+#define ISL12022_REG_SCA0 0x10
+#define ISL12022_REG_MNA0 0x11
+#define ISL12022_REG_HRA0 0x12
+#define ISL12022_REG_DTA0 0x13
+#define ISL12022_REG_MOA0 0x14
+#define ISL12022_REG_DWA0 0x15
+#define ISL12022_ALARM_SECTION ISL12022_REG_SCA0
+#define ISL12022_ALARM_SECTION_LEN (ISL12022_REG_DWA0 - ISL12022_REG_SCA0 + 1)
+
+/* TEMP - Temperature sensor registers */
#define ISL12022_REG_TEMP_L 0x28

/* ISL register bits */
#define ISL12022_HR_MIL (1 << 7) /* military or 24 hour time */

+#define ISL12022_SR_ALM (1 << 4)
#define ISL12022_SR_LBAT85 (1 << 2)
#define ISL12022_SR_LBAT75 (1 << 1)

+#define ISL12022_INT_ARST (1 << 7)
#define ISL12022_INT_WRTC (1 << 6)
+#define ISL12022_INT_IM (1 << 5)
+#define ISL12022_INT_FOBATB (1 << 4)
#define ISL12022_INT_FO_MASK GENMASK(3, 0)
#define ISL12022_INT_FO_OFF 0x0
#define ISL12022_INT_FO_32K 0x1
@@ -52,10 +67,18 @@
#define ISL12022_REG_VB85_MASK GENMASK(5, 3)
#define ISL12022_REG_VB75_MASK GENMASK(2, 0)

+#define ISL12022_ALARM_ENABLE (1 << 7) /* for all ALARM registers */
+
#define ISL12022_BETA_TSE (1 << 7)

+static struct i2c_driver isl12022_driver;
+
struct isl12022 {
+ struct i2c_client *i2c;
+ struct rtc_device *rtc;
struct regmap *regmap;
+ int irq;
+ bool irq_enabled;
};

static umode_t isl12022_hwmon_is_visible(const void *data,
@@ -215,6 +238,208 @@ static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
return regmap_bulk_write(regmap, ISL12022_REG_SC, buf, sizeof(buf));
}

+static int isl12022_rtc_read_alarm(struct device *dev,
+ struct rtc_wkalrm *alarm)
+{
+ struct rtc_time *const tm = &alarm->time;
+ struct isl12022 *isl12022 = dev_get_drvdata(dev);
+ struct regmap *regmap = isl12022->regmap;
+ uint8_t buf[ISL12022_ALARM_SECTION_LEN];
+ int ret, yr, i;
+
+ ret = regmap_bulk_read(regmap, ISL12022_ALARM_SECTION,
+ buf, sizeof(buf));
+ if (ret) {
+ dev_err(dev, "%s: reading ALARM registers failed\n",
+ __func__);
+ return ret;
+ }
+
+ dev_dbg(dev,
+ "%s: sc=%02x, mn=%02x, hr=%02x, dt=%02x, mo=%02x, dw=%02x\n",
+ __func__, buf[0], buf[1], buf[2], buf[3], buf[4], buf[5]);
+
+ tm->tm_sec = bcd2bin(buf[ISL12022_REG_SCA0 - ISL12022_ALARM_SECTION]
+ & 0x7F);
+ tm->tm_min = bcd2bin(buf[ISL12022_REG_MNA0 - ISL12022_ALARM_SECTION]
+ & 0x7F);
+ tm->tm_hour = bcd2bin(buf[ISL12022_REG_HRA0 - ISL12022_ALARM_SECTION]
+ & 0x3F);
+ tm->tm_mday = bcd2bin(buf[ISL12022_REG_DTA0 - ISL12022_ALARM_SECTION]
+ & 0x3F);
+ tm->tm_mon = bcd2bin(buf[ISL12022_REG_MOA0 - ISL12022_ALARM_SECTION]
+ & 0x1F) - 1;
+ tm->tm_wday = buf[ISL12022_REG_DWA0 - ISL12022_ALARM_SECTION] & 0x07;
+
+ /* The alarm doesn't store the year so get it from the rtc section */
+ ret = regmap_read(regmap, ISL12022_REG_YR, &yr);
+ if (ret) {
+ dev_err(dev, "%s: reading YR register failed\n", __func__);
+ return yr;
+ }
+ tm->tm_year = bcd2bin(yr) + 100;
+
+ for (i = 0 ; i < ISL12022_ALARM_SECTION_LEN ; i++) {
+ if (buf[i] & ISL12022_ALARM_ENABLE) {
+ alarm->enabled = 1;
+ break;
+ }
+ }
+
+ dev_dbg(dev, "%s: %ptR\n", __func__, tm);
+
+ return 0;
+}
+
+static int isl12022_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+ struct rtc_time *alarm_tm = &alarm->time;
+ struct isl12022 *isl12022 = dev_get_drvdata(dev);
+ struct regmap *regmap = isl12022->regmap;
+ u8 regs[ISL12022_ALARM_SECTION_LEN] = { 0, };
+ struct rtc_time rtc_tm;
+ int ret = 0, enable, dw;
+
+ ret = isl12022_rtc_read_time(dev, &rtc_tm);
+ if (ret)
+ return ret;
+
+ /* If the alarm time is before the current time disable the alarm */
+ if (!alarm->enabled || rtc_tm_sub(alarm_tm, &rtc_tm) <= 0)
+ enable = 0;
+ else
+ enable = ISL12022_ALARM_ENABLE;
+
+ /* Set non-matching tm_wday to safeguard against early false matching
+ * while setting all the alarm registers (this rtc lacks a general
+ * alarm/irq enable/disable bit).
+ */
+ if (enable) {
+ ret = regmap_read(regmap, ISL12022_REG_DW, &dw);
+ if (ret) {
+ dev_err(dev, "%s: reading DW failed\n", __func__);
+ return ret;
+ }
+ /* ~4 days into the future should be enough to avoid match */
+ dw = ((dw + 4) % 7) | ISL12022_ALARM_ENABLE;
+ ret = regmap_write(regmap, ISL12022_REG_DWA0, dw);
+ if (ret) {
+ dev_err(dev, "%s: writing DWA0 failed\n", __func__);
+ return ret;
+ }
+ }
+
+ /* Program the alarm and enable it for each setting */
+ regs[ISL12022_REG_SCA0 - ISL12022_ALARM_SECTION] =
+ bin2bcd(alarm_tm->tm_sec) | enable;
+ regs[ISL12022_REG_MNA0 - ISL12022_ALARM_SECTION] =
+ bin2bcd(alarm_tm->tm_min) | enable;
+ regs[ISL12022_REG_HRA0 - ISL12022_ALARM_SECTION] =
+ bin2bcd(alarm_tm->tm_hour) | enable;
+ regs[ISL12022_REG_DTA0 - ISL12022_ALARM_SECTION] =
+ bin2bcd(alarm_tm->tm_mday) | enable;
+ regs[ISL12022_REG_MOA0 - ISL12022_ALARM_SECTION] =
+ bin2bcd(alarm_tm->tm_mon + 1) | enable;
+ regs[ISL12022_REG_DWA0 - ISL12022_ALARM_SECTION] =
+ bin2bcd(alarm_tm->tm_wday & 7) | enable;
+
+ /* write ALARM registers */
+ ret = regmap_bulk_write(regmap, ISL12022_REG_SCA0,
+ &regs, sizeof(regs));
+ if (ret) {
+ dev_err(dev, "%s: writing ALARM registers failed\n", __func__);
+ return ret;
+ }
+
+ return 0;
+}
+
+static irqreturn_t isl12022_rtc_interrupt(int irq, void *data)
+{
+ struct isl12022 *isl12022 = data;
+ struct rtc_device *rtc = isl12022->rtc;
+ struct device *dev = &rtc->dev;
+ struct regmap *regmap = isl12022->regmap;
+ u32 val = 0;
+ unsigned long events = 0;
+ int ret;
+
+ ret = regmap_read(regmap, ISL12022_REG_SR, &val);
+ if (ret) {
+ dev_err(dev, "%s: reading SR failed\n", __func__);
+ return IRQ_HANDLED;
+ }
+
+ if (val & ISL12022_SR_ALM)
+ events |= RTC_IRQF | RTC_AF;
+
+ if (events & RTC_AF)
+ dev_dbg(dev, "alarm!\n");
+
+ if (!events)
+ return IRQ_NONE;
+
+ rtc_update_irq(rtc, 1, events);
+ return IRQ_HANDLED;
+}
+
+static int isl12022_rtc_alarm_irq_enable(struct device *dev,
+ unsigned int enabled)
+{
+ struct isl12022 *isl12022 = dev_get_drvdata(dev);
+
+ if (!isl12022->irq_enabled == !enabled)
+ return 0;
+
+ if (enabled)
+ enable_irq(isl12022->irq);
+ else
+ disable_irq(isl12022->irq);
+
+ isl12022->irq_enabled = !!enabled;
+
+ return 0;
+}
+
+static int isl12022_setup_irq(struct isl12022 *isl12022, int irq)
+{
+ struct device *dev = &isl12022->i2c->dev;
+ struct regmap *regmap = isl12022->regmap;
+ unsigned int reg_mask, reg_val;
+ u8 buf[ISL12022_ALARM_SECTION_LEN] = { 0, };
+ int ret;
+
+ /* Clear and disable all alarm registers */
+ ret = regmap_bulk_write(regmap, ISL12022_ALARM_SECTION,
+ buf, sizeof(buf));
+ if (ret)
+ return ret;
+
+ /* Enable automatic reset of ALM bit, enable single event interrupt
+ * mode, and disable IRQ/fOUT pin during battery-backup mode.
+ */
+ reg_mask = ISL12022_INT_ARST | ISL12022_INT_IM
+ | ISL12022_INT_FOBATB | ISL12022_INT_FO_MASK;
+ reg_val = ISL12022_INT_ARST | ISL12022_INT_FOBATB | ISL12022_INT_FO_OFF;
+ ret = regmap_write_bits(regmap, ISL12022_REG_INT,
+ reg_mask, reg_val);
+ if (ret)
+ return ret;
+
+ ret = devm_request_threaded_irq(dev, irq, NULL,
+ isl12022_rtc_interrupt,
+ IRQF_SHARED | IRQF_ONESHOT,
+ isl12022_driver.driver.name,
+ isl12022);
+ if (ret) {
+ dev_err(dev, "Unable to request irq %d\n", irq);
+ return ret;
+ }
+
+ isl12022->irq = irq;
+ return 0;
+}
+
static int isl12022_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
{
struct isl12022 *isl12022 = dev_get_drvdata(dev);
@@ -246,6 +471,9 @@ static const struct rtc_class_ops isl12022_rtc_ops = {
.ioctl = isl12022_rtc_ioctl,
.read_time = isl12022_rtc_read_time,
.set_time = isl12022_rtc_set_time,
+ .read_alarm = isl12022_rtc_read_alarm,
+ .set_alarm = isl12022_rtc_set_alarm,
+ .alarm_irq_enable = isl12022_rtc_alarm_irq_enable,
};

static const struct regmap_config regmap_config = {
@@ -347,6 +575,7 @@ static int isl12022_probe(struct i2c_client *client)
isl12022 = devm_kzalloc(&client->dev, sizeof(*isl12022), GFP_KERNEL);
if (!isl12022)
return -ENOMEM;
+ isl12022->i2c = client;

regmap = devm_regmap_init_i2c(client, &regmap_config);
if (IS_ERR(regmap)) {
@@ -367,11 +596,20 @@ static int isl12022_probe(struct i2c_client *client)
rtc = devm_rtc_allocate_device(&client->dev);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
+ isl12022->rtc = rtc;

rtc->ops = &isl12022_rtc_ops;
rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
rtc->range_max = RTC_TIMESTAMP_END_2099;

+ if (client->irq > 0) {
+ ret = isl12022_setup_irq(isl12022, client->irq);
+ if (ret)
+ return ret;
+ } else {
+ clear_bit(RTC_FEATURE_ALARM, rtc->features);
+ }
+
return devm_rtc_register_device(rtc);
}


--
2.46.0