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Thu, 11 Mar 2021 17:50:03 +0000 From: Francois Gervais To: linux-rtc@vger.kernel.org Cc: Alessandro Zummo , Alexandre Belloni , Michael McCormick , linux-kernel@vger.kernel.org, Francois Gervais Subject: [PATCH 1/1] rtc: pcf85063: add integrity check Date: Thu, 11 Mar 2021 12:49:40 -0500 Message-Id: <20210311174940.23072-1-fgervais@distech-controls.com> X-Mailer: git-send-email 2.17.1 Content-Type: text/plain X-Originating-IP: [174.92.176.122] X-ClientProxiedBy: BL0PR02CA0137.namprd02.prod.outlook.com (2603:10b6:208:35::42) To DM6PR01MB4265.prod.exchangelabs.com (2603:10b6:5:22::33) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from localhost.localdomain (174.92.176.122) by BL0PR02CA0137.namprd02.prod.outlook.com (2603:10b6:208:35::42) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3912.17 via Frontend Transport; Thu, 11 Mar 2021 17:50:02 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-HT: Tenant X-MS-Office365-Filtering-Correlation-Id: 1997d6d5-adb1-4005-f323-08d8e4b61959 X-MS-TrafficTypeDiagnostic: DM6PR01MB3721: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: x-pp-identifier: acuityo365 X-MS-Oob-TLC-OOBClassifiers: OLM:8882; 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For example, we've seen COF bits flips and then the output clock frequency would not be the expected one anymore. To remediate this issue, this adds an optional feature where if the OS bit it set on boot, it's possibly because the RTC lost power and again possibly because a new battery has been inserted. In that case, it reapplies defaults to configuration registers. Signed-off-by: Francois Gervais --- drivers/rtc/rtc-pcf85063.c | 54 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) diff --git a/drivers/rtc/rtc-pcf85063.c b/drivers/rtc/rtc-pcf85063.c index 463991c74fdd..774cc4cf93d8 100644 --- a/drivers/rtc/rtc-pcf85063.c +++ b/drivers/rtc/rtc-pcf85063.c @@ -57,6 +57,10 @@ #define PCF85063_REG_ALM_S 0x0b #define PCF85063_AEN BIT(7) +static bool integrity_check; +module_param(integrity_check, bool, 0444); +MODULE_PARM_DESC(integrity_check, "Set to one to enable the integrity check."); + struct pcf85063_config { struct regmap_config regmap; unsigned has_alarms:1; @@ -357,6 +361,49 @@ static int pcf85063_load_capacitance(struct pcf85063 *pcf85063, PCF85063_REG_CTRL1_CAP_SEL, reg); } +static int pcf85063_check_integrity(struct pcf85063 *pcf85063) +{ + int err; + unsigned int val; + + err = regmap_read(pcf85063->regmap, PCF85063_REG_SC, &val); + if (err < 0) { + dev_warn(&pcf85063->rtc->dev, "failed to read OS bit: %d", + err); + return err; + } + + if (!(val & PCF85063_REG_SC_OS)) { + dev_dbg(&pcf85063->rtc->dev, "integrity is ok\n"); + return 0; + } + + dev_dbg(&pcf85063->rtc->dev, "Power loss detected, restoring defaults\n"); + err = regmap_update_bits(pcf85063->regmap, PCF85063_REG_CTRL1, + (unsigned int)~PCF85063_REG_CTRL1_CAP_SEL, 0); + if (err < 0) + goto err_restore; + + err = regmap_write(pcf85063->regmap, PCF85063_REG_CTRL2, 0); + if (err < 0) + goto err_restore; + + err = regmap_write(pcf85063->regmap, PCF85063_REG_OFFSET, 0); + if (err < 0) + goto err_restore; + + err = regmap_write(pcf85063->regmap, PCF85063_REG_RAM, 0); + if (err < 0) + goto err_restore; + + return 0; + + +err_restore: + dev_err(&pcf85063->rtc->dev, "failed to restore defaults: %d", err); + return err; +} + #ifdef CONFIG_COMMON_CLK /* * Handling of the clkout @@ -558,6 +605,13 @@ static int pcf85063_probe(struct i2c_client *client) dev_warn(&client->dev, "failed to set xtal load capacitance: %d", err); + if (integrity_check) { + err = pcf85063_check_integrity(pcf85063); + if (err < 0) + dev_warn(&client->dev, "failed to check integrity: %d", + err); + } + pcf85063->rtc->ops = &pcf85063_rtc_ops; pcf85063->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000; pcf85063->rtc->range_max = RTC_TIMESTAMP_END_2099; -- 2.17.1