--- /dev/null
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2019, Vaisala Oyj
+ */
+
+#include <common.h>
+#include <command.h>
+#include <dm.h>
+#include <i2c.h>
+#include <rtc.h>
+
+/*
+ * RTC register addresses
+ */
+#define RTC_SEC_REG_ADDR 0x00
+#define RTC_MIN_REG_ADDR 0x01
+#define RTC_HR_REG_ADDR 0x02
+#define RTC_DAY_REG_ADDR 0x03
+#define RTC_DATE_REG_ADDR 0x04
+#define RTC_MON_REG_ADDR 0x05
+#define RTC_YR_REG_ADDR 0x06
+#define RTC_CTL_REG_ADDR 0x0e
+#define RTC_STAT_REG_ADDR 0x0f
+#define RTC_TEST_REG_ADDR 0x13
+
+/*
+ * RTC control register bits
+ */
+#define RTC_CTL_BIT_A1IE BIT(0) /* Alarm 1 interrupt enable */
+#define RTC_CTL_BIT_A2IE BIT(1) /* Alarm 2 interrupt enable */
+#define RTC_CTL_BIT_INTCN BIT(2) /* Interrupt control */
+#define RTC_CTL_BIT_DOSC BIT(7) /* Disable Oscillator */
+
+/*
+ * RTC status register bits
+ */
+#define RTC_STAT_BIT_A1F BIT(0) /* Alarm 1 flag */
+#define RTC_STAT_BIT_A2F BIT(1) /* Alarm 2 flag */
+#define RTC_STAT_BIT_EN32KHZ BIT(3) /* Enable 32KHz Output */
+#define RTC_STAT_BIT_BB32KHZ BIT(6) /* Battery backed 32KHz Output */
+#define RTC_STAT_BIT_OSF BIT(7) /* Oscillator stop flag */
+
+/*
+ * RTC test register bits
+ */
+#define RTC_TEST_BIT_SWRST BIT(7) /* Software reset */
+
+#define RTC_DATE_TIME_REG_SIZE 7
+#define RTC_SRAM_START 0x14
+#define RTC_SRAM_END 0xFF
+#define RTC_SRAM_SIZE 236
+
+struct ds3232_priv_data {
+ u8 max_register;
+ u8 sram_start;
+ int sram_size;
+};
+
+static int ds3232_rtc_read8(struct udevice *dev, unsigned int reg)
+{
+ int ret;
+ u8 buf;
+ struct ds3232_priv_data *priv_data;
+
+ priv_data = dev_get_priv(dev);
+ if (!priv_data)
+ return -EINVAL;
+
+ if (reg > priv_data->max_register)
+ return -EINVAL;
+
+ ret = dm_i2c_read(dev, reg, &buf, sizeof(buf));
+ if (ret < 0)
+ return ret;
+
+ return buf;
+}
+
+static int ds3232_rtc_write8(struct udevice *dev, unsigned int reg, int val)
+{
+ u8 buf = (u8)val;
+ struct ds3232_priv_data *priv_data;
+
+ priv_data = dev_get_priv(dev);
+ if (!priv_data)
+ return -EINVAL;
+
+ if (reg > priv_data->max_register)
+ return -EINVAL;
+
+ return dm_i2c_write(dev, reg, &buf, sizeof(buf));
+}
+
+static int reset_sram(struct udevice *dev)
+{
+ int ret, sram_end, reg;
+ struct ds3232_priv_data *priv_data;
+
+ priv_data = dev_get_priv(dev);
+ if (!priv_data)
+ return -EINVAL;
+
+ sram_end = priv_data->sram_start + priv_data->sram_size;
+
+ for (reg = priv_data->sram_start; reg < sram_end; reg++) {
+ ret = ds3232_rtc_write8(dev, reg, 0x00);
+ if (ret < 0)
+ return ret;
+ }
+
+ return 0;
+}
+
+static int verify_osc(struct udevice *dev)
+{
+ int ret, rtc_status;
+
+ ret = ds3232_rtc_read8(dev, RTC_STAT_REG_ADDR);
+ if (ret < 0)
+ return ret;
+
+ rtc_status = ret;
+
+ if (rtc_status & RTC_STAT_BIT_OSF) {
+ dev_warn(dev,
+ "oscillator discontinuity flagged, time unreliable\n");
+ /*
+ * In case OSC was off we cannot trust the SRAM data anymore.
+ * Reset it to 0x00.
+ */
+ ret = reset_sram(dev);
+ if (ret < 0)
+ return ret;
+ }
+
+ return 0;
+}
+
+static int ds3232_rtc_set(struct udevice *dev, const struct rtc_time *tm)
+{
+ u8 buf[RTC_DATE_TIME_REG_SIZE];
+ u8 is_century;
+
+ if (tm->tm_year < 1900 || tm->tm_year > 2099)
+ dev_warn(dev, "WARNING: year should be between 1900 and 2099!\n");
+
+ is_century = (tm->tm_year >= 2000) ? 0x80 : 0;
+
+ buf[RTC_SEC_REG_ADDR] = bin2bcd(tm->tm_sec);
+ buf[RTC_MIN_REG_ADDR] = bin2bcd(tm->tm_min);
+ buf[RTC_HR_REG_ADDR] = bin2bcd(tm->tm_hour);
+ buf[RTC_DAY_REG_ADDR] = bin2bcd(tm->tm_wday + 1);
+ buf[RTC_DATE_REG_ADDR] = bin2bcd(tm->tm_mday);
+ buf[RTC_MON_REG_ADDR] = bin2bcd(tm->tm_mon) | is_century;
+ buf[RTC_YR_REG_ADDR] = bin2bcd(tm->tm_year % 100);
+
+ return dm_i2c_write(dev, 0, buf, sizeof(buf));
+}
+
+static int ds3232_rtc_get(struct udevice *dev, struct rtc_time *tm)
+{
+ int ret;
+ u8 buf[RTC_DATE_TIME_REG_SIZE];
+ u8 is_twelve_hr;
+ u8 is_pm;
+ u8 is_century;
+
+ ret = verify_osc(dev);
+ if (ret < 0)
+ return ret;
+
+ ret = dm_i2c_read(dev, 0, buf, sizeof(buf));
+ if (ret < 0)
+ return ret;
+
+ /* Extract additional information for AM/PM and century */
+ is_twelve_hr = buf[RTC_HR_REG_ADDR] & 0x40;
+ is_pm = buf[RTC_HR_REG_ADDR] & 0x20;
+ is_century = buf[RTC_MON_REG_ADDR] & 0x80;
+
+ tm->tm_sec = bcd2bin(buf[RTC_SEC_REG_ADDR] & 0x7F);
+ tm->tm_min = bcd2bin(buf[RTC_MIN_REG_ADDR] & 0x7F);
+
+ if (is_twelve_hr)
+ tm->tm_hour = bcd2bin(buf[RTC_HR_REG_ADDR] & 0x1F)
+ + (is_pm ? 12 : 0);
+ else
+ tm->tm_hour = bcd2bin(buf[RTC_HR_REG_ADDR]);
+
+ tm->tm_wday = bcd2bin((buf[RTC_DAY_REG_ADDR] & 0x07) - 1);
+ tm->tm_mday = bcd2bin(buf[RTC_DATE_REG_ADDR] & 0x3F);
+ tm->tm_mon = bcd2bin((buf[RTC_MON_REG_ADDR] & 0x7F));
+ tm->tm_year = bcd2bin(buf[RTC_YR_REG_ADDR])
+ + (is_century ? 2000 : 1900);
+ tm->tm_yday = 0;
+ tm->tm_isdst = 0;
+
+ return 0;
+}
+
+static int ds3232_rtc_reset(struct udevice *dev)
+{
+ int ret;
+
+ ret = reset_sram(dev);
+ if (ret < 0)
+ return ret;
+
+ /*
+ * From datasheet
+ * (https://datasheets.maximintegrated.com/en/ds/DS3232M.pdf):
+ *
+ * The device reset occurs during the normal acknowledge time slot
+ * following the receipt of the data byte carrying that
+ * SWRST instruction a NACK occurs due to the resetting action.
+ *
+ * Therefore we don't verify the result of I2C write operation since it
+ * will fail due the NACK.
+ */
+ ds3232_rtc_write8(dev, RTC_TEST_REG_ADDR, RTC_TEST_BIT_SWRST);
+
+ return 0;
+}
+
+static int ds3232_probe(struct udevice *dev)
+{
+ int rtc_status;
+ int ret;
+ struct ds3232_priv_data *priv_data;
+
+ priv_data = dev_get_priv(dev);
+ if (!priv_data)
+ return -EINVAL;
+
+ priv_data->sram_start = RTC_SRAM_START;
+ priv_data->max_register = RTC_SRAM_END;
+ priv_data->sram_size = RTC_SRAM_SIZE;
+
+ ret = ds3232_rtc_read8(dev, RTC_STAT_REG_ADDR);
+ if (ret < 0)
+ return ret;
+
+ rtc_status = ret;
+
+ ret = verify_osc(dev);
+ if (ret < 0)
+ return ret;
+
+ rtc_status &= ~(RTC_STAT_BIT_OSF | RTC_STAT_BIT_A1F | RTC_STAT_BIT_A2F);
+
+ return ds3232_rtc_write8(dev, RTC_STAT_REG_ADDR, rtc_status);
+}
+
+static const struct rtc_ops ds3232_rtc_ops = {
+ .get = ds3232_rtc_get,
+ .set = ds3232_rtc_set,
+ .reset = ds3232_rtc_reset,
+ .read8 = ds3232_rtc_read8,
+ .write8 = ds3232_rtc_write8
+};
+
+static const struct udevice_id ds3232_rtc_ids[] = {
+ { .compatible = "dallas,ds3232" },
+ { }
+};
+
+U_BOOT_DRIVER(rtc_ds3232) = {
+ .name = "rtc-ds3232",
+ .id = UCLASS_RTC,
+ .probe = ds3232_probe,
+ .of_match = ds3232_rtc_ids,
+ .ops = &ds3232_rtc_ops,
+ .priv_auto_alloc_size = sizeof(struct ds3232_priv_data),
+};
projects / oweals / u-boot.git / commitdiff