Message-ID: <56609CCD.2020701@timesys.com>
Date:	Thu, 3 Dec 2015 14:49:33 -0500
From:	Akshay Bhat <akshay.bhat@...esys.com>
To:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Cc:	a.zummo@...ertech.it, rtc-linux@...glegroups.com,
	linux-kernel@...r.kernel.org, justin.waters@...esys.com
Subject: Re: [PATCH] rtc: Add Epson RX8010SJ RTC driver

Thanks for the detailed feedback and mentioning --strict option for 
checkpatch :) I have fixed all the issues in the v2 version of the 
patch: https://lkml.org/lkml/2015/12/3/606

On 12/02/2015 06:40 PM, Alexandre Belloni wrote:
> On 11/11/2015 at 17:31:58 -0500, Akshay Bhat wrote :
>> diff --git a/drivers/rtc/rtc-rx8010.c b/drivers/rtc/rtc-rx8010.c
>> new file mode 100644
>> index 0000000..9b8bd76
>> --- /dev/null
>> +++ b/drivers/rtc/rtc-rx8010.c
>> @@ -0,0 +1,570 @@
>> +/*
>> + * Driver for the Epson RTC module RX-8010 SJ
>> + *
>> + * Copyright(C) Timesys Corporation 2015
>> + * Copyright(C) General Electric Company 2015
>> + * Copyright(C) SEIKO EPSON CORPORATION 2013. All rights reserved.
>> + *
>> + * Derived from RX-8025 driver:
>> + * Copyright (C) 2009 Wolfgang Grandegger <wg@...ndegger.com>
>> + *
>> + * Copyright (C) 2005 by Digi International Inc.
>> + * All rights reserved.
>> + *
>> + * Modified by fengjh at rising.com.cn
>> + * <http://lists.lm-sensors.org/mailman/listinfo/lm-sensors>
>> + * 2006.11
>> + *
>> + * Code cleanup by Sergei Poselenov, <sposelenov@...raft.com>
>> + * Converted to new style by Wolfgang Grandegger <wg@...ndegger.com>
>> + * Alarm and periodic interrupt added by Dmitry Rakhchev <rda@...raft.com>
>> + *
>
> Please remove all those unnecessary copyrights, the original
> rx-8025 has been heavily rewritten anyway.
>
>> +static int rx8010_read_reg(struct i2c_client *client, int number, u8 *value)
>> +{
>> +	int ret = i2c_smbus_read_byte_data(client, number);
>> +
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	*value = ret;
>> +	return 0;
>> +}
>
> I don't see the benefit of that function, calling
> i2c_smbus_read_byte_data directly is more efficient.
>
>> +
>> +static int rx8010_read_regs(struct i2c_client *client, int number, u8 length,
>> +			u8 *values)
>> +{
>> +	int ret = i2c_smbus_read_i2c_block_data(client, number, length, values);
>> +
>> +	if (ret != length)
>> +		return ret < 0 ? ret : -EIO;
>> +
>> +	return 0;
>> +}
>
> Apart from the error handling, I'd say the same for that function.
>
>> +
>> +static irqreturn_t rx8010_irq_1_handler(int irq, void *dev_id)
>> +{
>> +	struct i2c_client *client = dev_id;
>> +	struct rx8010_data *rx8010 = i2c_get_clientdata(client);
>> +	u8 flagreg;
>> +
>> +	spin_lock(&rx8010->flags_lock);
>> +
>> +	if (rx8010_read_reg(client, RX8010_FLAG, &flagreg)) {
>> +		spin_unlock(&rx8010->flags_lock);
>> +		return IRQ_NONE;
>> +	}
>> +
>> +	if (flagreg & RX8010_FLAG_VLF)
>> +		dev_warn(&client->dev, "Frequency stop detected\n");
>> +
>> +	if (flagreg & RX8010_FLAG_TF) {
>> +		flagreg &= ~RX8010_FLAG_TF;
>> +		rtc_update_irq(rx8010->rtc, 1, RTC_PF | RTC_IRQF);
>> +	}
>> +
>> +	if (flagreg & RX8010_FLAG_AF) {
>> +		flagreg &= ~RX8010_FLAG_AF;
>> +		rtc_update_irq(rx8010->rtc, 1, RTC_AF | RTC_IRQF);
>> +	}
>> +
>> +	if (flagreg & RX8010_FLAG_UF) {
>> +		flagreg &= ~RX8010_FLAG_UF;
>> +		rtc_update_irq(rx8010->rtc, 1, RTC_UF | RTC_IRQF);
>> +	}
>> +
>> +	i2c_smbus_write_byte_data(client, RX8010_FLAG, flagreg);
>> +
>> +	spin_unlock(&rx8010->flags_lock);
>> +	return IRQ_HANDLED;
>> +}
>> +
>> +static int rx8010_get_time(struct device *dev, struct rtc_time *dt)
>> +{
>> +	struct rx8010_data *rx8010 = dev_get_drvdata(dev);
>> +	u8 date[7];
>> +	u8 flagreg;
>> +	int err;
>> +
>> +	err = rx8010_read_reg(rx8010->client, RX8010_FLAG, &flagreg);
>> +	if (err)
>> +		return err;
>> +
>> +	if (flagreg & RX8010_FLAG_VLF) {
>> +		dev_warn(dev, "Frequency stop detected\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	err = rx8010_read_regs(rx8010->client, RX8010_SEC, 7, date);
>> +	if (err)
>> +		return err;
>> +
>> +	dt->tm_sec = bcd2bin(date[RX8010_SEC-RX8010_SEC] & 0x7f);
>> +	dt->tm_min = bcd2bin(date[RX8010_MIN-RX8010_SEC] & 0x7f);
>> +	dt->tm_hour = bcd2bin(date[RX8010_HOUR-RX8010_SEC] & 0x3f);
>> +	dt->tm_mday = bcd2bin(date[RX8010_MDAY-RX8010_SEC] & 0x3f);
>> +	dt->tm_mon = bcd2bin(date[RX8010_MONTH-RX8010_SEC] & 0x1f) - 1;
>> +	dt->tm_year = bcd2bin(date[RX8010_YEAR-RX8010_SEC]);
>> +	dt->tm_wday = bcd2bin(date[RX8010_WDAY-RX8010_SEC] & 0x7f);
>> +
>
> This is not the correct value for tm_wday, you should use ffs(), not
> that anybody actually cares.
>
> Also, checkpatch --strict complains about missing spaces around those '-'
> and a few alignments are not correct, can fix those?
>
>
>> +	if (dt->tm_year < 70)
>> +		dt->tm_year += 100;
>> +
>
> I'd say that we don't care about handling dates before 2000 and that the
> range should be 2000-2100 as this is actually the range where the leap
> year calculation is correct. Also your are not respecting that in
> rx8010_set_time() so setting a date in 2072 will end up reading 1972.
>
>> +	return rtc_valid_tm(dt);
>> +}
>> +
>> +static int rx8010_set_time(struct device *dev, struct rtc_time *dt)
>> +{
>> +	struct rx8010_data *rx8010 = dev_get_drvdata(dev);
>> +	u8 date[7];
>> +	u8 ctrl, flagreg;
>> +	int ret;
>> +	unsigned long irqflags;
>> +
>> +	/* BUG: The HW assumes every year that is a multiple of 4 to be a leap
>> +	 * year.  Next time this is wrong is 2100, which will not be a leap
>> +	 * year.
>> +	 */
>> +
>
> Then, return -EINVAL if the year is out of the 100-200 range.
>
>
>> +	/* set STOP bit before changing clock/calendar */
>> +	ret = rx8010_read_reg(rx8010->client, RX8010_CTRL, &ctrl);
>> +	if (ret)
>> +		return ret;
>> +	rx8010->ctrlreg = ctrl | RX8010_CTRL_STOP;
>> +	ret = i2c_smbus_write_byte_data(rx8010->client, RX8010_CTRL,
>> +		rx8010->ctrlreg);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	date[RX8010_SEC-RX8010_SEC] = bin2bcd(dt->tm_sec);
>> +	date[RX8010_MIN-RX8010_SEC] = bin2bcd(dt->tm_min);
>> +	date[RX8010_HOUR-RX8010_SEC] = bin2bcd(dt->tm_hour);
>> +	date[RX8010_MDAY-RX8010_SEC] = bin2bcd(dt->tm_mday);
>> +	date[RX8010_MONTH-RX8010_SEC] = bin2bcd(dt->tm_mon + 1);
>> +	date[RX8010_YEAR-RX8010_SEC] = bin2bcd(dt->tm_year % 100);
>> +	date[RX8010_WDAY-RX8010_SEC] = bin2bcd(dt->tm_wday);
>
> this is not the expected value for RX8010_WDAY, it must be 1 <<
> dt->tm_wday, see the datasheet.
>
>> +
>> +	ret = i2c_smbus_write_i2c_block_data(rx8010->client,
>> +			RX8010_SEC, 7, date);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	/* clear STOP bit after changing clock/calendar */
>> +	ret = rx8010_read_reg(rx8010->client, RX8010_CTRL, &ctrl);
>> +	if (ret)
>> +		return ret;
>> +	rx8010->ctrlreg = ctrl & ~RX8010_CTRL_STOP;
>> +	ret = i2c_smbus_write_byte_data(rx8010->client, RX8010_CTRL,
>> +		rx8010->ctrlreg);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	spin_lock_irqsave(&rx8010->flags_lock, irqflags);
>> +
>> +	ret = rx8010_read_reg(rx8010->client, RX8010_FLAG, &flagreg);
>> +	if (ret) {
>> +		spin_unlock_irqrestore(&rx8010->flags_lock, irqflags);
>> +		return ret;
>> +	}
>> +
>> +	if (flagreg & RX8010_FLAG_VLF)
>> +		ret = i2c_smbus_write_byte_data(rx8010->client, RX8010_FLAG,
>> +					flagreg & ~RX8010_FLAG_VLF);
>> +
>> +	spin_unlock_irqrestore(&rx8010->flags_lock, irqflags);
>> +
>> +	return 0;
>> +}
>> +
>> +static int rx8010_init_client(struct i2c_client *client)
>> +{
>> +	struct rx8010_data *rx8010 = i2c_get_clientdata(client);
>> +	u8 ctrl[3];
>> +	int need_clear = 0, need_reset = 0, err = 0;
>> +
>> +	/* Initialize reserved registers as specified in datasheet */
>> +	err = i2c_smbus_write_byte_data(client, RX8010_RESV17, 0xD8);
>> +	if (err < 0)
>> +		return err;
>> +
>> +	err = i2c_smbus_write_byte_data(client, RX8010_RESV30, 0x00);
>> +	if (err < 0)
>> +		return err;
>> +
>> +	err = i2c_smbus_write_byte_data(client, RX8010_RESV31, 0x08);
>> +	if (err < 0)
>> +		return err;
>> +
>> +	err = i2c_smbus_write_byte_data(client, RX8010_IRQ, 0x00);
>> +	if (err < 0)
>> +		return err;
>> +
>> +	err = rx8010_read_regs(rx8010->client, RX8010_EXT, 3, ctrl);
>> +	if (err)
>> +		return err;
>> +
>> +	if ((ctrl[1] & RX8010_FLAG_VLF)) {
>> +		dev_warn(&client->dev, "Frequency stop was detected\n");
>> +		need_reset = 1;
>> +	}
>> +
>> +	if (ctrl[1] & RX8010_FLAG_AF) {
>> +		dev_warn(&client->dev, "Alarm was detected\n");
>> +		need_clear = 1;
>> +	}
>> +
>> +	if (ctrl[1] & RX8010_FLAG_TF)
>> +		need_clear = 1;
>> +
>> +	if (ctrl[1] & RX8010_FLAG_UF)
>> +		need_clear = 1;
>> +
>> +	if (need_reset) {
>> +		ctrl[0] = ctrl[1] = ctrl[2] = 0;
>> +		err = i2c_smbus_write_i2c_block_data(client, RX8010_EXT,
>> +				3, ctrl);
>> +		if (err < 0)
>> +			return err;
>
> Please don't do that, reseting RX8010_FLAG_VLF will make userspace
> believe that the bogus date is valid.
>
>> +	} else if (need_clear) {
>> +		err = i2c_smbus_write_byte_data(client, RX8010_FLAG, 0x00);
>> +		if (err < 0)
>> +			return err;
>> +	}
>> +
>> +	rx8010->ctrlreg = (ctrl[2] & ~RX8010_CTRL_TEST);
>> +
>
> BTW, I'm not sure about the necessity to cache ctrl. It actually only saves one
> i2c read in the alarm functions.
>
>> +	return err;
>> +}
>> +
>
>
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