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Message-ID: <f30b5ceb77e44e7b74fd19b0c620d27a3c612e94.camel@gmail.com>
Date: Thu, 16 Jan 2025 08:16:25 +0000
From: Nuno Sá <noname.nuno@...il.com>
To: pavithra.u@...log.com, Antoniu Miclaus <antoniu.miclaus@...log.com>, 
 Alexandre Belloni <alexandre.belloni@...tlin.com>, Rob Herring
 <robh@...nel.org>, Krzysztof Kozlowski	 <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Jean Delvare	 <jdelvare@...e.com>, Guenter Roeck
 <linux@...ck-us.net>, Christophe JAILLET	 <christophe.jaillet@...adoo.fr>
Cc: linux-rtc@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org
Subject: Re: [PATCH v3 2/2] rtc: max31335: Add driver support for max31331

On Thu, 2025-01-09 at 15:59 +0530, PavithraUdayakumar-adi via B4 Relay wrote:
> From: PavithraUdayakumar-adi <pavithra.u@...log.com>
> 
> MAX31331 is an ultra-low-power, I2C Real-Time Clock RTC.
> 
> Signed-off-by: PavithraUdayakumar-adi <pavithra.u@...log.com>
> ---
>  drivers/rtc/rtc-max31335.c | 163 +++++++++++++++++++++++++++++++++-----------
> -
>  1 file changed, 120 insertions(+), 43 deletions(-)
> 
> diff --git a/drivers/rtc/rtc-max31335.c b/drivers/rtc/rtc-max31335.c
> index
> 3fbcf5f6b92ffd4581e9c4dbc87ec848867522dc..9d8f220fba2b21fc6393d67bff47f99b0227
> c707 100644
> --- a/drivers/rtc/rtc-max31335.c
> +++ b/drivers/rtc/rtc-max31335.c
> @@ -184,31 +184,88 @@
>  #define MAX31335_RAM_SIZE			32
>  #define MAX31335_TIME_SIZE			0x07
>  
> +/* MAX31331 Register Map */
> +#define MAX31331_RTC_CONFIG2			0x04
> +
>  #define clk_hw_to_max31335(_hw) container_of(_hw, struct max31335_data,
> clkout)
>  
> +/* Supported Maxim RTC */
> +enum max_rtc_ids {
> +	ID_MAX31331,
> +	ID_MAX31335,
> +	MAX_RTC_ID_NR
> +};
> +
> +struct chip_desc {
> +	u8 sec_reg;
> +	u8 alarm1_sec_reg;
> +
> +	u8 int_en_reg;
> +	u8 int_status_reg;
> +
> +	u8 ram_reg;
> +	u8 ram_size;
> +
> +	u8 temp_reg;
> +
> +	u8 trickle_reg;
> +
> +	u8 clkout_reg;
> +};
> +
>  struct max31335_data {
> +	enum max_rtc_ids id;
>  	struct regmap *regmap;
>  	struct rtc_device *rtc;
>  	struct clk_hw clkout;
> +	struct clk *clkin;
> +	const struct chip_desc *chip;
> +	int irq;
>  };
>  
>  static const int max31335_clkout_freq[] = { 1, 64, 1024, 32768 };
>  
> +static const struct chip_desc chip[MAX_RTC_ID_NR] = {
> +	[ID_MAX31331] = {
> +		.int_en_reg = 0x01,
> +		.int_status_reg = 0x00,
> +		.sec_reg = 0x08,
> +		.alarm1_sec_reg = 0x0F,
> +		.ram_reg = 0x20,
> +		.ram_size = 32,
> +		.trickle_reg = 0x1B,
> +		.clkout_reg = 0x04,
> +	},
> +	[ID_MAX31335] = {
> +		.int_en_reg = 0x01,
> +		.int_status_reg = 0x00,
> +		.sec_reg = 0x0A,
> +		.alarm1_sec_reg = 0x11,
> +		.ram_reg = 0x40,
> +		.ram_size = 32,
> +		.temp_reg = 0x35,
> +		.trickle_reg = 0x1D,
> +		.clkout_reg = 0x06,
> +	},
> +};
> +
>  static const u16 max31335_trickle_resistors[] = {3000, 6000, 11000};
>  
>  static bool max31335_volatile_reg(struct device *dev, unsigned int reg)
>  {
> +	struct max31335_data *max31335 = dev_get_drvdata(dev);
> +	const struct chip_desc *chip = max31335->chip;
> +
>  	/* time keeping registers */
> -	if (reg >= MAX31335_SECONDS &&
> -	    reg < MAX31335_SECONDS + MAX31335_TIME_SIZE)
> +	if (reg >= chip->sec_reg && reg < chip->sec_reg + MAX31335_TIME_SIZE)
>  		return true;
>  
>  	/* interrupt status register */
> -	if (reg == MAX31335_STATUS1)
> +	if (reg == chip->int_status_reg)
>  		return true;
>  
> -	/* temperature registers */
> -	if (reg == MAX31335_TEMP_DATA_MSB || reg == MAX31335_TEMP_DATA_LSB)
> +	/* temperature registers if valid */
> +	if (chip->temp_reg && (reg == chip->temp_reg || reg == chip->temp_reg
> + 1))
>  		return true;
>  
>  	return false;
> @@ -227,7 +284,7 @@ static int max31335_read_time(struct device *dev, struct
> rtc_time *tm)
>  	u8 date[7];
>  	int ret;
>  
> -	ret = regmap_bulk_read(max31335->regmap, MAX31335_SECONDS, date,
> +	ret = regmap_bulk_read(max31335->regmap, max31335->chip->sec_reg,
> date,
>  			       sizeof(date));
>  	if (ret)
>  		return ret;
> @@ -262,7 +319,7 @@ static int max31335_set_time(struct device *dev, struct
> rtc_time *tm)
>  	if (tm->tm_year >= 200)
>  		date[5] |= FIELD_PREP(MAX31335_MONTH_CENTURY, 1);
>  
> -	return regmap_bulk_write(max31335->regmap, MAX31335_SECONDS, date,
> +	return regmap_bulk_write(max31335->regmap, max31335->chip->sec_reg,
> date,
>  				 sizeof(date));
>  }
>  
> @@ -273,7 +330,7 @@ static int max31335_read_alarm(struct device *dev, struct
> rtc_wkalrm *alrm)
>  	struct rtc_time time;
>  	u8 regs[6];
>  
> -	ret = regmap_bulk_read(max31335->regmap, MAX31335_ALM1_SEC, regs,
> +	ret = regmap_bulk_read(max31335->regmap, max31335->chip-
> >alarm1_sec_reg, regs,
>  			       sizeof(regs));
>  	if (ret)
>  		return ret;
> @@ -292,11 +349,11 @@ static int max31335_read_alarm(struct device *dev,
> struct rtc_wkalrm *alrm)
>  	if (time.tm_year >= 200)
>  		alrm->time.tm_year += 100;
>  
> -	ret = regmap_read(max31335->regmap, MAX31335_INT_EN1, &ctrl);
> +	ret = regmap_read(max31335->regmap, max31335->chip->int_en_reg,
> &ctrl);
>  	if (ret)
>  		return ret;
>  
> -	ret = regmap_read(max31335->regmap, MAX31335_STATUS1, &status);
> +	ret = regmap_read(max31335->regmap, max31335->chip->int_status_reg,
> &status);
>  	if (ret)
>  		return ret;
>  
> @@ -320,18 +377,18 @@ static int max31335_set_alarm(struct device *dev, struct
> rtc_wkalrm *alrm)
>  	regs[4] = bin2bcd(alrm->time.tm_mon + 1);
>  	regs[5] = bin2bcd(alrm->time.tm_year % 100);
>  
> -	ret = regmap_bulk_write(max31335->regmap, MAX31335_ALM1_SEC,
> +	ret = regmap_bulk_write(max31335->regmap, max31335->chip-
> >alarm1_sec_reg,
>  				regs, sizeof(regs));
>  	if (ret)
>  		return ret;
>  
>  	reg = FIELD_PREP(MAX31335_INT_EN1_A1IE, alrm->enabled);
> -	ret = regmap_update_bits(max31335->regmap, MAX31335_INT_EN1,
> +	ret = regmap_update_bits(max31335->regmap, max31335->chip-
> >int_en_reg,
>  				 MAX31335_INT_EN1_A1IE, reg);
>  	if (ret)
>  		return ret;
>  
> -	ret = regmap_update_bits(max31335->regmap, MAX31335_STATUS1,
> +	ret = regmap_update_bits(max31335->regmap, max31335->chip-
> >int_status_reg,
>  				 MAX31335_STATUS1_A1F, 0);
>  
>  	return 0;
> @@ -341,23 +398,33 @@ static int max31335_alarm_irq_enable(struct device *dev,
> unsigned int enabled)
>  {
>  	struct max31335_data *max31335 = dev_get_drvdata(dev);
>  
> -	return regmap_update_bits(max31335->regmap, MAX31335_INT_EN1,
> +	return regmap_update_bits(max31335->regmap, max31335->chip-
> >int_en_reg,
>  				  MAX31335_INT_EN1_A1IE, enabled);
>  }
>  
>  static irqreturn_t max31335_handle_irq(int irq, void *dev_id)
>  {
>  	struct max31335_data *max31335 = dev_id;
> -	bool status;
> -	int ret;
> +	struct mutex *lock = &max31335->rtc->ops_lock;
> +	int ret, status;
> +
> +	mutex_lock(lock);
>  
> -	ret = regmap_update_bits_check(max31335->regmap, MAX31335_STATUS1,
> -				       MAX31335_STATUS1_A1F, 0, &status);
> +	ret = regmap_read(max31335->regmap, max31335->chip->int_status_reg,
> &status);
>  	if (ret)
> -		return IRQ_HANDLED;
> +		goto exit;
> +
> +	if (FIELD_GET(MAX31335_STATUS1_A1F, status)) {
> +		ret = regmap_update_bits(max31335->regmap, max31335->chip-
> >int_status_reg,
> +					 MAX31335_STATUS1_A1F, 0);
> +		if (ret)
> +			goto exit;
>  
> -	if (status)
>  		rtc_update_irq(max31335->rtc, 1, RTC_AF | RTC_IRQF);
> +	}
> +
> +exit:
> +	mutex_unlock(lock);
>  
>  	return IRQ_HANDLED;
>  }
> @@ -404,7 +471,7 @@ static int max31335_trickle_charger_setup(struct device
> *dev,
>  
>  	i = i + trickle_cfg;
>  
> -	return regmap_write(max31335->regmap, MAX31335_TRICKLE_REG,
> +	return regmap_write(max31335->regmap, max31335->chip->trickle_reg,
>  			    FIELD_PREP(MAX31335_TRICKLE_REG_TRICKLE, i) |
>  			    FIELD_PREP(MAX31335_TRICKLE_REG_EN_TRICKLE,
>  				       chargeable));
> @@ -418,7 +485,7 @@ static unsigned long max31335_clkout_recalc_rate(struct
> clk_hw *hw,
>  	unsigned int reg;
>  	int ret;
>  
> -	ret = regmap_read(max31335->regmap, MAX31335_RTC_CONFIG2, &reg);
> +	ret = regmap_read(max31335->regmap, max31335->chip->clkout_reg,
> &reg);
>  	if (ret)
>  		return 0;
>  
> @@ -449,23 +516,23 @@ static int max31335_clkout_set_rate(struct clk_hw *hw,
> unsigned long rate,
>  			     ARRAY_SIZE(max31335_clkout_freq));
>  	freq_mask = __roundup_pow_of_two(ARRAY_SIZE(max31335_clkout_freq)) -
> 1;
>  
> -	return regmap_update_bits(max31335->regmap, MAX31335_RTC_CONFIG2,
> -				  freq_mask, index);
> +	return regmap_update_bits(max31335->regmap, max31335->chip-
> >clkout_reg,
> +				 freq_mask, index);
>  }
>  
>  static int max31335_clkout_enable(struct clk_hw *hw)
>  {
>  	struct max31335_data *max31335 = clk_hw_to_max31335(hw);
>  
> -	return regmap_set_bits(max31335->regmap, MAX31335_RTC_CONFIG2,
> -			       MAX31335_RTC_CONFIG2_ENCLKO);
> +	return regmap_set_bits(max31335->regmap, max31335->chip->clkout_reg,
> +			      MAX31335_RTC_CONFIG2_ENCLKO);
>  }
>  
>  static void max31335_clkout_disable(struct clk_hw *hw)
>  {
>  	struct max31335_data *max31335 = clk_hw_to_max31335(hw);
>  
> -	regmap_clear_bits(max31335->regmap, MAX31335_RTC_CONFIG2,
> +	regmap_clear_bits(max31335->regmap, max31335->chip->clkout_reg,
>  			  MAX31335_RTC_CONFIG2_ENCLKO);
>  }
>  
> @@ -475,7 +542,7 @@ static int max31335_clkout_is_enabled(struct clk_hw *hw)
>  	unsigned int reg;
>  	int ret;
>  
> -	ret = regmap_read(max31335->regmap, MAX31335_RTC_CONFIG2, &reg);
> +	ret = regmap_read(max31335->regmap, max31335->chip->clkout_reg,
> &reg);
>  	if (ret)
>  		return ret;
>  
> @@ -500,7 +567,7 @@ static int max31335_nvmem_reg_read(void *priv, unsigned
> int offset,
>  				   void *val, size_t bytes)
>  {
>  	struct max31335_data *max31335 = priv;
> -	unsigned int reg = MAX31335_TS0_SEC_1_128 + offset;
> +	unsigned int reg = max31335->chip->ram_reg + offset;
>  
>  	return regmap_bulk_read(max31335->regmap, reg, val, bytes);
>  }
> @@ -509,7 +576,7 @@ static int max31335_nvmem_reg_write(void *priv, unsigned
> int offset,
>  				    void *val, size_t bytes)
>  {
>  	struct max31335_data *max31335 = priv;
> -	unsigned int reg = MAX31335_TS0_SEC_1_128 + offset;
> +	unsigned int reg = max31335->chip->ram_reg + offset;
>  
>  	return regmap_bulk_write(max31335->regmap, reg, val, bytes);
>  }
> @@ -533,7 +600,7 @@ static int max31335_read_temp(struct device *dev, enum
> hwmon_sensor_types type,
>  	if (type != hwmon_temp || attr != hwmon_temp_input)
>  		return -EOPNOTSUPP;
>  
> -	ret = regmap_bulk_read(max31335->regmap, MAX31335_TEMP_DATA_MSB,
> +	ret = regmap_bulk_read(max31335->regmap, max31335->chip->temp_reg,
>  			       reg, 2);
>  	if (ret)
>  		return ret;
> @@ -577,8 +644,8 @@ static int max31335_clkout_register(struct device *dev)
>  	int ret;
>  
>  	if (!device_property_present(dev, "#clock-cells"))
> -		return regmap_clear_bits(max31335->regmap,
> MAX31335_RTC_CONFIG2,
> -					 MAX31335_RTC_CONFIG2_ENCLKO);
> +		return regmap_clear_bits(max31335->regmap, max31335->chip-
> >clkout_reg,
> +				  MAX31335_RTC_CONFIG2_ENCLKO);
>  
>  	max31335->clkout.init = &max31335_clk_init;
>  
> @@ -605,6 +672,7 @@ static int max31335_probe(struct i2c_client *client)
>  #if IS_REACHABLE(HWMON)
>  	struct device *hwmon;
>  #endif
> +	const struct chip_desc *match;
>  	int ret;
>  
>  	max31335 = devm_kzalloc(&client->dev, sizeof(*max31335), GFP_KERNEL);
> @@ -616,7 +684,11 @@ static int max31335_probe(struct i2c_client *client)
>  		return PTR_ERR(max31335->regmap);
>  
>  	i2c_set_clientdata(client, max31335);
> -
> +	match = i2c_get_match_data(client);
> +	if (!match)
> +		return -ENODEV;
> +	max31335->chip = match;
> +	max31335->id = max31335->chip - chip;

I kind of already expressed this internally... I can't agree with the above. Why
not making 'id' a member of 'struct chip_desc'? The above is very useless IMHO.

- Nuno Sá



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