RE: [PATCH v4 1/2] drivers: rtc: add max313xx series rtc driver

["Tilki, Ibrahim" <Ibrahim.Tilki@analog.com>]

> On 15/03/2023 19:16:25+0300, Ibrahim Tilki wrote:
> > +static int max313xx_trickle_charger_setup(struct device *dev)
> > +{
> > +	struct max313xx *rtc = dev_get_drvdata(dev);
> > +	bool trickle_diode_en;
> > +	u32 charger_en = 0;
> > +	int index, reg;
> > +	u32 ohms = 0;
> > +	int ret;
> > +
> > +	device_property_read_u32(dev, "aux-voltage-chargeable", &charger_en);
> > +	if (charger_en > 1)
> > +		return dev_err_probe(dev, -EINVAL,
> > +				     "invalid value %d for property aux-voltage-chargeable\n",
> > +				     charger_en);
> 
> This is too verbose, you can simply return -EINVAL here. dtbs_check will
> report the invalid value.
> 

will do.

> > +
> > +	if (!charger_en)
> > +		return 0;
> > +
> > +	trickle_diode_en = device_property_read_bool(dev, "adi,trickle-diode-enable");
> 
> There is no point having this property, simply use aux-voltage-chargeable.
> 

I will remove this and add enum value "2" to aux-voltage-chargable for charging with a diode.

> > +	device_property_read_u32(dev, "trickle-resistor-ohms", &ohms);
> > +
> > +	if (!rtc->chip->trickle_reg) {
> > +		dev_warn(dev, "device does not have trickle charger\n");
> 
> Simply return 0, no string.
> 

will do.

> > +		return 0;
> > +	}
> > +
> > +	index = find_closest(ohms, max313xx_trickle_ohms,
> > +			     ARRAY_SIZE(max313xx_trickle_ohms)) + 1;
> > +
> > +	switch (rtc->id) {
> > +	case ID_MAX31329:
> > +		reg = FIELD_PREP(MAX31329_TRICKLE_ENABLE_BIT, 1) |
> > +		      FIELD_PREP(MAX31329_43_TRICKLE_RES_MASK, index) |
> > +		      FIELD_PREP(MAX31329_43_TRICKLE_DIODE_EN, trickle_diode_en);
> > +		break;
> > +	case ID_MAX31331:
> > +	case ID_MAX31334:
> > +		reg = FIELD_PREP(MAX3133X_TRICKLE_ENABLE_BIT, 1) |
> > +		      FIELD_PREP(MAX3133X_TRICKLE_RES_MASK, index) |
> > +		      FIELD_PREP(MAX3133X_TRICKLE_DIODE_EN, trickle_diode_en);
> > +		break;
> > +	case ID_MAX31341:
> > +		if (index == 1)
> > +			index = 0;
> > +
> > +		reg = FIELD_PREP(MAX31341_TRICKLE_ENABLE_BIT, 1) |
> > +		      FIELD_PREP(MAX31341_TRICKLE_RES_MASK, index) |
> > +		      FIELD_PREP(MAX31341_TRICKLE_DIODE_EN, trickle_diode_en);
> > +
> > +		ret = regmap_set_bits(rtc->regmap, MAX31341_POWER_MGMT_REG,
> > +				      MAX31341_POWER_MGMT_TRICKLE_BIT);
> > +		if (ret)
> > +			return ret;
> > +
> > +		break;
> > +	case ID_MAX31343:
> > +		reg = FIELD_PREP(MAX31329_43_TRICKLE_RES_MASK, index) |
> > +		      FIELD_PREP(MAX31329_43_TRICKLE_DIODE_EN, trickle_diode_en) |
> > +		      FIELD_PREP(MAX31343_TRICKLE_ENABLE_MASK,
> > +				 MAX31343_TRICKLE_ENABLE_CODE);
> > +		break;
> > +	default:
> > +		return -EOPNOTSUPP;
> > +	}
> > +
> > +	return regmap_write(rtc->regmap, rtc->chip->trickle_reg, reg);
> > +}
> > +
> > +static int max313xx_find_clkin_freq_index(struct clk *clk)
> > +{
> > +	unsigned long rate = clk_get_rate(clk);
> > +	int freq;
> > +	int i;
> > +
> > +	i = find_closest(rate, max313xx_clkin_freq,
> > +			 ARRAY_SIZE(max313xx_clkin_freq));
> > +	if (max313xx_clkin_freq[i] == rate)
> > +		return i;
> > +
> > +	for (i = ARRAY_SIZE(max313xx_clkin_freq) - 1; i >= 0; i--) {
> > +		freq = max313xx_clkin_freq[i];
> > +		if (freq == clk_round_rate(clk, freq))
> > +			return i;
> > +	}
> > +
> > +	/* supplied clock cannot produce one of desired frequency rate */
> > +	return -ENODEV;
> > +}
> > +
> > +static int max313xx_clkin_init(struct device *dev)
> > +{
> > +	struct max313xx *rtc = dev_get_drvdata(dev);
> > +	int rate;
> > +	int ret;
> > +
> > +	rtc->clkin = devm_clk_get_enabled(dev, NULL);
> > +	if (IS_ERR(rtc->clkin)) {
> > +		if (PTR_ERR(rtc->clkin) == -ENOENT)
> > +			rtc->clkin = NULL;
> > +		else
> > +			return dev_err_probe(dev, PTR_ERR(rtc->clkin),
> > +					     "error while clkin setup\n");
> > +	}
> > +
> > +	if (!rtc->clkin) {
> > +		switch (rtc->id) {
> > +		case ID_MAX31329:
> > +			return regmap_clear_bits(rtc->regmap,
> > +						 MAX31329_CONFIG2_REG,
> > +						 MAX31329_CONFIG2_CLKIN_EN);
> > +		case ID_MAX31341:
> > +		case ID_MAX31342:
> > +			return regmap_clear_bits(rtc->regmap,
> > +						 MAX31341_42_CONFIG1_REG,
> > +						 MAX31341_42_CONFIG1_CLKIN_EN);
> > +		default:
> > +			return 0;
> > +		}
> > +	}
> > +
> > +	rate = max313xx_find_clkin_freq_index(rtc->clkin);
> > +	if (rate < 0)
> > +		return dev_err_probe(dev, rate,
> > +				     "clkin cannot produce required frequency\n");
> > +
> > +	ret = clk_set_rate(rtc->clkin, max313xx_clkin_freq[rate]);
> > +	if (ret)
> > +		return ret;
> > +
> > +	switch (rtc->id) {
> > +	case ID_MAX31329:
> > +		ret = regmap_update_bits(rtc->regmap, MAX31329_CONFIG2_REG,
> > +					 MAX31329_CONFIG2_CLKIN_FREQ, rate);
> > +		if (ret)
> > +			return ret;
> > +
> > +		return regmap_set_bits(rtc->regmap, MAX31329_CONFIG2_REG,
> > +				       MAX31329_CONFIG2_CLKIN_EN);
> > +	case ID_MAX31341:
> > +	case ID_MAX31342:
> > +		ret = regmap_update_bits(rtc->regmap, MAX31341_42_CONFIG1_REG,
> > +					 MAX31341_42_CONFIG1_CLKIN_FREQ,
> > +					 FIELD_PREP(MAX31341_42_CONFIG1_CLKIN_FREQ, rate));
> > +		if (ret)
> > +			return ret;
> > +
> > +		return regmap_set_bits(rtc->regmap, MAX31341_42_CONFIG1_REG,
> > +				       MAX31341_42_CONFIG1_CLKIN_EN);
> > +	default:
> > +		rtc->clkin = NULL;
> > +		dev_warn(dev, "device does not have clock input\n");
> > +		return 0;
> > +	}
> > +}
> > +
> > +static int max313xx_irq_init(struct device *dev, const char *devname)
> > +{
> > +	struct max313xx *rtc = dev_get_drvdata(dev);
> > +	int ret;
> > +
> > +	switch (rtc->id) {
> > +	case ID_MAX31328:
> > +		/* max31328 sqw and interrupt pin is shared */
> > +		if (rtc->irq > 0 && rtc->clkout.clk)
> > +			return dev_err_probe(dev, -EOPNOTSUPP,
> > +					     "cannot have both sqw clock output and irq enabled");
> 
> This still doesn't work, having a clock registered doesn't mean it is
> used or muxed. Also, you want to always register it so it gets disabled
> when it is not used.
> 

I can't wrap my head around this. What is the point of registering a clock when the pin
is used for IRQ? What should the driver do if a user wants to enable clockout?
Wouldn't that cause continuous interrupts? Or should the driver simply don't care?

Same condition also applies for other RTCs that have two interrupt lines.
What is your comment on the default case below: "irq not possible when both clkin and clkout are configured"?

> > +
> > +		break;
> > +	case ID_MAX31331:
> > +	case ID_MAX31334:
> > +		if (rtc->clkout.clk) {
> > +			/*
> > +			 * interrupt muxing depends on clkout so enable clkout
> > +			 * if configured before requesting interrupt
> > +			 */
> > +			ret = clk_prepare_enable(rtc->clkout.clk);
> > +			if (ret)
> > +				return dev_err_probe(dev, ret,
> > +						     "cannot enable clkout\n");
> > +		}
> > +		break;
> > +	default:
> > +		if (rtc->clkin) {
> > +			if (rtc->clkout.clk && rtc->irq > 0)
> > +				return dev_err_probe(dev, -EOPNOTSUPP,
> > +						     "irq not possible when both clkin and clkout are configured\n");
> > +
> > +			if (rtc->irq <= 0)
> > +				break;
> > +
> > +			/* clkout needs to be disabled for interrupt */
> > +			if (rtc->chip->clkout->en_invert)
> > +				ret = regmap_set_bits(rtc->regmap,
> > +						      rtc->chip->clkout->reg,
> > +						      rtc->chip->clkout->en_bit);
> > +			else
> > +				ret = regmap_clear_bits(rtc->regmap,
> > +							rtc->chip->clkout->reg,
> > +							rtc->chip->clkout->en_bit);
> > +
> 
> What if you want alarm1 on INTA without any clkin? This doesn't seem to
> be configured.
> 

alarm1 interrupt is muxed into INTA/CLKIN pin by default.
So if clkin is not configured, no action needed since the clkin is already
disabled in "max313xx_clkin_init", alarm1 is muxed into INTA in that case.


> > +			if (ret)
> > +				return ret;
> > +		}
> > +		break;
> > +	}
> > +
> > +	if (rtc->irq > 0) {
> > +		return devm_request_threaded_irq(dev, rtc->irq, NULL,
> > +						 &max313xx_irq, IRQF_ONESHOT,
> > +						 devname, rtc);
> > +	}
> 
> You still want to parse wakeup-source in case INTA/INTB is connected
> directly to a PMIC for exemple.
> 

will do.

> > +
> > +	clear_bit(RTC_FEATURE_ALARM, rtc->rtc->features);
> > +
> > +	return 0;
> > +}
> > +
> > +static int max313xx_probe(struct i2c_client *client,
> > +			  const struct i2c_device_id *id)
> > +{
> > +	struct device *dev = &client->dev;
> > +	struct max313xx *max313xx;
> > +	struct device *hwmon;
> > +	const void *match;
> > +	int ret;
> > +
> > +	max313xx->irq = client->irq;
> > +
> > +	ret = max313xx_clkout_register(dev);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = max313xx_clkin_init(dev);
> > +	if (ret)
> > +		return ret;
> > +
> > +	/* IRQ wiring depends on the clock configuration so parse them first */
> > +	ret = max313xx_irq_init(dev, client->name);
> > +	if (ret)
> > +		return ret;
> > +
> > +	if (max313xx->chip->ram_size) {
> > +		max313xx_nvmem_cfg.size = max313xx->chip->ram_size;
> > +		max313xx_nvmem_cfg.priv = max313xx;
> > +
> > +		ret = devm_rtc_nvmem_register(max313xx->rtc, &max313xx_nvmem_cfg);
> > +		if (ret)
> > +			dev_warn(dev, "cannot register rtc nvmem\n");
> > +	}
> > +
> > +	if (max313xx->chip->temp_reg) {
> > +		hwmon = devm_hwmon_device_register_with_info(dev, client->name,
> > +							     max313xx,
> > +							     &max313xx_chip_info,
> > +							     NULL);
> > +		if (IS_ERR(hwmon))
> > +			dev_warn(dev, "cannot register hwmon device: %li\n",
> > +				 PTR_ERR(hwmon));
> > +	}
> > +
> > +	return max313xx_trickle_charger_setup(dev);
> > +}
> > +
> > +static const struct of_device_id max313xx_of_id[] = {
> > +	{ .compatible = "adi,max31328", .data = &chip[ID_MAX31328] },
> > +	{ .compatible = "adi,max31329", .data = &chip[ID_MAX31329] },
> > +	{ .compatible = "adi,max31331", .data = &chip[ID_MAX31331] },
> > +	{ .compatible = "adi,max31334", .data = &chip[ID_MAX31334] },
> > +	{ .compatible = "adi,max31341", .data = &chip[ID_MAX31341] },
> > +	{ .compatible = "adi,max31342", .data = &chip[ID_MAX31342] },
> > +	{ .compatible = "adi,max31343", .data = &chip[ID_MAX31343] },
> > +	{ }
> > +};
> > +MODULE_DEVICE_TABLE(of, max313xx_of_id);
> > +
> > +static const struct i2c_device_id max313xx_id[] = {
> > +	{ "max31328", (kernel_ulong_t)&chip[ID_MAX31328] },
> > +	{ "max31329", (kernel_ulong_t)&chip[ID_MAX31329] },
> > +	{ "max31331", (kernel_ulong_t)&chip[ID_MAX31331] },
> > +	{ "max31334", (kernel_ulong_t)&chip[ID_MAX31334] },
> > +	{ "max31341", (kernel_ulong_t)&chip[ID_MAX31341] },
> > +	{ "max31342", (kernel_ulong_t)&chip[ID_MAX31342] },
> > +	{ "max31343", (kernel_ulong_t)&chip[ID_MAX31343] },
> > +	{ }
> > +};
> > +MODULE_DEVICE_TABLE(i2c, max313xx_id);
> > +
> > +static struct i2c_driver max313xx_driver = {
> > +	.driver = {
> > +		.name	= "rtc-max313xx",
> > +		.of_match_table = max313xx_of_id,
> > +	},
> > +	.probe		= max313xx_probe,
> > +	.id_table	= max313xx_id,
> > +};
> > +module_i2c_driver(max313xx_driver);
> > +
> > +MODULE_DESCRIPTION("Analog Devices MAX313XX RTCs");
> > +MODULE_AUTHOR("Zeynep Arslanbenzer <Zeynep.Arslanbenzer@analog.com>");
> > +MODULE_AUTHOR("Ibrahim Tilki <Ibrahim.Tilki@analog.com>");
> > +MODULE_SOFTDEP("pre: regmap-i2c");
> > +MODULE_LICENSE("GPL");
> > +MODULE_VERSION("1.0");
> > -- 
> > 2.25.1
> > 
> 
> -- 
> Alexandre Belloni, co-owner and COO, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com

Regards,
Ibrahim