Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754185AbYJ2Scf (ORCPT ); Wed, 29 Oct 2008 14:32:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753142AbYJ2Sc0 (ORCPT ); Wed, 29 Oct 2008 14:32:26 -0400 Received: from xes-mad.com ([216.165.139.214]:38167 "EHLO xes-mad.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752142AbYJ2ScZ (ORCPT ); Wed, 29 Oct 2008 14:32:25 -0400 X-Greylist: delayed 3762 seconds by postgrey-1.27 at vger.kernel.org; Wed, 29 Oct 2008 14:32:25 EDT From: Nate Case To: David Brownell Cc: linux-kernel@vger.kernel.org, Nate Case Subject: [PATCH] rtc-ds1307: Reset bogus register values on m41t00 Date: Wed, 29 Oct 2008 12:29:37 -0500 Message-Id: <1225301377-9092-1-git-send-email-ncase@xes-inc.com> X-Mailer: git-send-email 1.6.0.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3604 Lines: 112 On the M41T00, registers are in a random state if the Vbat power was lost before the driver probes it (regardless of whether or not the oscillator is still running). In this case, give all registers valid values so that the bogus values don't cause it to error out and skip the device. Signed-off-by: Nate Case --- drivers/rtc/rtc-ds1307.c | 61 +++++++++++++++++++++++++++++++++++---------- 1 files changed, 47 insertions(+), 14 deletions(-) diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c index 162330b..aec17bb 100644 --- a/drivers/rtc/rtc-ds1307.c +++ b/drivers/rtc/rtc-ds1307.c @@ -198,6 +198,29 @@ static irqreturn_t ds1307_irq(int irq, void *dev_id) /*----------------------------------------------------------------------*/ +static int ds1307_regs_valid(struct ds1307 *ds1307) +{ + int tmp, valid = 1; + + tmp = bcd2bin(ds1307->regs[DS1307_REG_SECS] & 0x7f); + if (tmp > 60) + valid = 0; + + tmp = bcd2bin(ds1307->regs[DS1307_REG_MIN] & 0x7f); + if (tmp > 60) + valid = 0; + + tmp = bcd2bin(ds1307->regs[DS1307_REG_MDAY] & 0x3f); + if (tmp == 0 || tmp > 31) + valid = 0; + + tmp = bcd2bin(ds1307->regs[DS1307_REG_MONTH] & 0x1f); + if (tmp == 0 || tmp > 12) + valid = 0; + + return valid; +} + static int ds1307_get_time(struct device *dev, struct rtc_time *t) { struct ds1307 *ds1307 = dev_get_drvdata(dev); @@ -571,6 +594,7 @@ static int __devinit ds1307_probe(struct i2c_client *client, const struct chip_desc *chip = &chips[id->driver_data]; struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent); int want_irq = false; + int already_reset = false; if (!i2c_check_functionality(adapter, I2C_FUNC_I2C | I2C_FUNC_SMBUS_WRITE_BYTE_DATA)) @@ -663,6 +687,28 @@ read_rtc: switch (ds1307->type) { case ds_1307: case m41t00: + /* + * Registers can be in random state if the Vbat power + * was lost, and sometimes this will happen even with + * the oscillator running. Give all registers valid + * values so that the bogus values don't cause it to + * error out later on. + */ + if (!ds1307_regs_valid(ds1307)) { + if (already_reset) + goto exit_bad; + i2c_smbus_write_byte_data(client, DS1307_REG_YEAR, 1); + i2c_smbus_write_byte_data(client, DS1307_REG_MONTH, 1); + i2c_smbus_write_byte_data(client, DS1307_REG_MDAY, 1); + i2c_smbus_write_byte_data(client, DS1307_REG_WDAY, 1); + i2c_smbus_write_byte_data(client, DS1307_REG_HOUR, 0); + i2c_smbus_write_byte_data(client, DS1307_REG_MIN, 0); + i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 1); + dev_warn(&client->dev, "reset bogus registers\n"); + already_reset = true; + goto read_rtc; + } + /* clock halted? turn it on, so clock can tick. */ if (tmp & DS1307_BIT_CH) { i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0); @@ -707,20 +753,7 @@ read_rtc: break; } - tmp = ds1307->regs[DS1307_REG_SECS]; - tmp = bcd2bin(tmp & 0x7f); - if (tmp > 60) - goto exit_bad; - tmp = bcd2bin(ds1307->regs[DS1307_REG_MIN] & 0x7f); - if (tmp > 60) - goto exit_bad; - - tmp = bcd2bin(ds1307->regs[DS1307_REG_MDAY] & 0x3f); - if (tmp == 0 || tmp > 31) - goto exit_bad; - - tmp = bcd2bin(ds1307->regs[DS1307_REG_MONTH] & 0x1f); - if (tmp == 0 || tmp > 12) + if (!ds1307_regs_valid(ds1307)) goto exit_bad; tmp = ds1307->regs[DS1307_REG_HOUR]; -- 1.6.0.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/