Confusion of control 2 register contents

[joshld]

The contents of the CONTROL 2 register (ABB5ZES3_REG_CTRL2, 0x01) contains status flags for various interrupts and enable/disable bits for timers. The bits being modified in this call, which are all the same bit in this case (bit 7), is a read-only bit so the call has no effect. The correct method to perform what has been documented is to update the associated register for each alarm individually, setting that one bit.

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[admsev]

@gooroodev what do you think?

[gooroodev]

Thanks for the heads-up, @admsev!

Review of Pull Request: Confusion of control 2 register contents

1. Summary of Changes

The pull request refactors the function abb5zes3_rtc_check_setup to update the alarm enable bits for each alarm component (minute, hour, date, and day of the week) individually rather than collectively. The changes involve:

• Removing the single call to regmap_update_bits that updated the ABB5ZES3_REG_CTRL2 register for all alarm enable bits.
• Adding separate calls to regmap_update_bits for each alarm component (minute, hour, date, and day of the week).

2. Issues, Bugs, or Typos in Code

Issue 1: Incorrect Register for Alarm Enable Bits
The original code updated the ABB5ZES3_REG_CTRL2 register to disable all alarm settings collectively. The new code updates the individual alarm registers (ABB5ZES3_REG_ALRM_MN, ABB5ZES3_REG_ALRM_HR, ABB5ZES3_REG_ALRM_DT, ABB5ZES3_REG_ALRM_DW) instead. This change is correct and aligns with the datasheet's specification where each alarm component has its own register.

Issue 2: Code Duplication
The new implementation introduces code duplication by calling regmap_update_bits separately for each alarm component. This can be refactored to reduce redundancy.

Proposed Improved Code:
Refactor the repeated code into a helper function to update the alarm enable bits for each component.

static int disable_alarm_component(struct device *dev, struct regmap *regmap, unsigned int reg, u8 mask, const char *component)
{
    int ret = regmap_update_bits(regmap, reg, mask, mask);
    if (ret < 0) {
        dev_err(dev, "%s: unable to disable %s alarm setting (%d)\n", __func__, component, ret);
    }
    return ret;
}

static int abb5zes3_rtc_check_setup(struct device *dev)
{
    struct abb5zes3_rtc_data *data = dev_get_drvdata(dev);
    struct regmap *regmap = data->regmap;
    unsigned int reg;
    int ret;
    u8 mask;

    /* Disable all alarm settings */
    ret = disable_alarm_component(dev, regmap, ABB5ZES3_REG_ALRM_MN, ABB5ZES3_REG_ALRM_MN_AE, "minute");
    if (ret < 0) return ret;

    ret = disable_alarm_component(dev, regmap, ABB5ZES3_REG_ALRM_HR, ABB5ZES3_REG_ALRM_HR_AE, "hour");
    if (ret < 0) return ret;

    ret = disable_alarm_component(dev, regmap, ABB5ZES3_REG_ALRM_DT, ABB5ZES3_REG_ALRM_DT_AE, "day");
    if (ret < 0) return ret;

    ret = disable_alarm_component(dev, regmap, ABB5ZES3_REG_ALRM_DW, ABB5ZES3_REG_ALRM_DW_AE, "weekday");
    if (ret < 0) return ret;

    /* Set Control 1 register (RTC enabled, 24hr mode, all int. disabled) */
    mask = (ABB5ZES3_REG_CTRL1_CIE | ABB5ZES3_REG_CTRL1_AIE |
            ABB5ZES3_REG_CTRL1_SIE | ABB5ZES3_REG_CTRL1_PM |
            ABB5ZES3_REG_CTRL1_CAP | ABB5ZES3_REG_CTRL1_STOP);
    ret = regmap_update_bits(regmap, ABB5ZES3_REG_CTRL1, mask, 0);
    if (ret < 0) {
        dev_err(dev, "%s: unable to initialize CTRL1 register (%d)\n", __func__, ret);
        return ret;
    }

    /* Set Control 2 register (timer int. disabled, alarm status cleared) */
    mask = (ABB5ZES3_REG_CTRL2_CTBIE | ABB5ZES3_REG_CTRL2_CTAIE |
            ABB5ZES3_REG_CTRL2_WTAIE | ABB5ZES3_REG_CTRL2_AF |
            ABB5ZES3_REG_CTRL2_SF | ABB5ZES3_REG_CTRL2_CTBF |
            ABB5ZES3_REG_CTRL2_CTAF);
    ret = regmap_update_bits(regmap, ABB5ZES3_REG_CTRL2, mask, 0);
    if (ret < 0) {
        dev_err(dev, "%s: unable to initialize CTRL2 register (%d)\n", __func__, ret);
        return ret;
    }

    /* Enable battery low detection function and battery switchover function */
    mask = (ABB5ZES3_REG_CTRL3_PM0  | ABB5ZES3_REG_CTRL3_PM1 |
            ABB5ZES3_REG_CTRL3_PM2  | ABB5ZES3_REG_CTRL3_BLIE |
            ABB5ZES3_REG_CTRL3_BSIE | ABB5ZES3_REG_CTRL3_BSF);
    ret = regmap_update_bits(regmap, ABB5ZES3_REG_CTRL3, mask, 0);
    if (ret < 0) {
        dev_err(dev, "%s: unable to initialize CTRL3 register (%d)\n", __func__, ret);
        return ret;
    }

    /* Check oscillator integrity flag */
    ret = regmap_read(regmap, ABB5ZES3_REG_RTC_SC, &reg);
    if (ret < 0) {
        dev_err(dev, "%s: unable to read osc. integrity flag (%d)\n", __func__, ret);
        return ret;
    }

    if (reg & ABB5ZES3_REG_RTC_SC_OSC) {
        dev_err(dev, "clock integrity not guaranteed. Osc. has stopped or has been interrupted.\n");
        dev_err(dev, "change battery (if not already done) and then set time to reset osc. failure flag.\n");
    }

    /* Check battery low flag at startup */
    ret = regmap_read(regmap, ABB5ZES3_REG_CTRL3, &reg);
    if (ret < 0) {
        dev_err(dev, "%s: unable to read battery low flag (%d)\n", __func__, ret);
        return ret;
    }

    data->battery_low = reg & ABB5ZES3_REG_CTRL3_BLF;
    if (data->battery_low) {
        dev_err(dev, "RTC battery is low; please, consider changing it!\n");

        ret = _abb5zes3_rtc_battery_low_irq_enable(regmap, false);
        if (ret)
            dev_err(dev, "%s: disabling battery low interrupt generation failed (%d)\n", __func__, ret);
    }

    return ret;
}

3. General Review of Code Quality and Style

Code Quality:

• The code is generally well-structured and follows the Linux kernel coding guidelines.
• The use of regmap for register access is appropriate and ensures clean and maintainable code.
• Error handling is consistent and provides meaningful error messages.

Code Style:

• The code adheres to the Linux kernel coding style, including proper indentation, use of __func__ for function names in log messages, and consistent naming conventions.
• The use of comments is adequate, explaining the purpose of each significant block of code.

Suggested Improvements:

• Refactor repetitive code into helper functions to improve readability and maintainability.
• Ensure that all log messages provide sufficient context to understand the error or status being reported.

Overall, the proposed changes improve the correctness of the alarm enable bit updates and maintain the high quality of the existing codebase.

Yours, Gooroo.dev. React or reply to give your feedback!