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https://github.com/brain-hackers/u-boot-brain
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rtc: m41t62: reset SQW in m41t62_rtc_reset
This takes care of resetting the 32kHz square wave, which is used by some boards as clock source for the SoC. Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
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@ -22,6 +22,7 @@
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#include <log.h>
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#include <rtc.h>
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#include <i2c.h>
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#include <linux/log2.h>
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#define M41T62_REG_SSEC 0
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#define M41T62_REG_SEC 1
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@ -49,6 +50,11 @@
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#define M41T62_FLAGS_AF (1 << 6) /* AF: Alarm Flag Bit */
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#define M41T62_FLAGS_BATT_LOW (1 << 4) /* BL: Battery Low Bit */
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#define M41T62_WDAY_SQW_FREQ_MASK 0xf0
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#define M41T62_WDAY_SQW_FREQ_SHIFT 4
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#define M41T62_SQW_MAX_FREQ 32768
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#define M41T62_FEATURE_HT (1 << 0)
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#define M41T62_FEATURE_BL (1 << 1)
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@ -139,21 +145,92 @@ static int m41t62_rtc_set(struct udevice *dev, const struct rtc_time *tm)
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return 0;
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}
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static int m41t62_rtc_reset(struct udevice *dev)
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static int m41t62_sqw_enable(struct udevice *dev, bool enable)
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{
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u8 val;
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int ret;
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ret = dm_i2c_read(dev, M41T62_REG_ALARM_MON, &val, sizeof(val));
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if (ret)
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return ret;
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if (enable)
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val |= M41T62_ALMON_SQWE;
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else
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val &= ~M41T62_ALMON_SQWE;
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return dm_i2c_write(dev, M41T62_REG_ALARM_MON, &val, sizeof(val));
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}
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static int m41t62_sqw_set_rate(struct udevice *dev, unsigned int rate)
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{
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u8 val, newval, sqwrateval;
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int ret;
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if (rate >= M41T62_SQW_MAX_FREQ)
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sqwrateval = 1;
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else if (rate >= M41T62_SQW_MAX_FREQ / 4)
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sqwrateval = 2;
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else if (rate)
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sqwrateval = 15 - ilog2(rate);
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ret = dm_i2c_read(dev, M41T62_REG_WDAY, &val, sizeof(val));
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if (ret)
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return ret;
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newval = val;
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newval &= ~M41T62_WDAY_SQW_FREQ_MASK;
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newval |= (sqwrateval << M41T62_WDAY_SQW_FREQ_SHIFT);
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/*
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* Try to avoid writing unchanged values. Writing to this register
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* will reset the internal counter pipeline and thus affect system
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* time.
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*/
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if (newval == val)
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return 0;
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return dm_i2c_write(dev, M41T62_REG_WDAY, &newval, sizeof(newval));
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}
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static int m41t62_rtc_clear_ht(struct udevice *dev)
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{
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u8 val;
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int ret;
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/*
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* M41T82: Make sure HT (Halt Update) bit is cleared.
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* This bit is 0 in M41T62 so its save to clear it always.
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*/
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int ret = dm_i2c_read(dev, M41T62_REG_ALARM_HOUR, &val, sizeof(val));
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ret = dm_i2c_read(dev, M41T62_REG_ALARM_HOUR, &val, sizeof(val));
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if (ret)
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return ret;
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val &= ~M41T80_ALHOUR_HT;
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ret |= dm_i2c_write(dev, M41T62_REG_ALARM_HOUR, &val, sizeof(val));
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ret = dm_i2c_write(dev, M41T62_REG_ALARM_HOUR, &val, sizeof(val));
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if (ret)
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return ret;
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return ret;
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return 0;
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}
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static int m41t62_rtc_reset(struct udevice *dev)
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{
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int ret;
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ret = m41t62_rtc_clear_ht(dev);
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if (ret)
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return ret;
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/*
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* Some boards feed the square wave as clock input into
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* the SoC. This enables a 32.768kHz square wave, which is
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* also the hardware default after power-loss.
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*/
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ret = m41t62_sqw_set_rate(dev, 32768);
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if (ret)
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return ret;
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return m41t62_sqw_enable(dev, true);
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}
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/*
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@ -162,7 +239,7 @@ static int m41t62_rtc_reset(struct udevice *dev)
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*/
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static int m41t62_rtc_probe(struct udevice *dev)
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{
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return m41t62_rtc_reset(dev);
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return m41t62_rtc_clear_ht(dev);
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}
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static const struct rtc_ops m41t62_rtc_ops = {
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