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- // 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>
- #include <dm/device_compat.h>
- #include <linux/bitops.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),
- };
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