Re: [PATCH] rtc: Add Epson RX8010SJ RTC driver

From: Akshay Bhat
Date: Thu Dec 03 2015 - 14:49:41 EST

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@xxxxxxxxxxxxxx>
+ *
+ * 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@xxxxxxxxxxx>
+ * Converted to new style by Wolfgang Grandegger <wg@xxxxxxxxxxxxxx>
+ * Alarm and periodic interrupt added by Dmitry Rakhchev <rda@xxxxxxxxxxx>
+ *

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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