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rtc: max31335: Add driver support for MAX31331
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MAX31331 is an ultra-low-power, I2C Real-Time Clock RTC

Signed-off-by: Swaroop Kukkillaya <[email protected]>
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@SwaroopPKADI
SwaroopPKADI authored and swaroop committed Oct 16, 2024
1 parent 04fbdbb commit 7bd079d
Showing 1 changed file with 121 additions and 40 deletions.
161 changes: 121 additions & 40 deletions drivers/rtc/rtc-max31335.c
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Original file line number Diff line number Diff line change
Expand Up @@ -184,31 +184,90 @@
#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 || 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;
Expand All @@ -227,7 +286,7 @@ 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;
Expand Down Expand Up @@ -262,7 +321,7 @@ 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));
}

Expand All @@ -273,7 +332,7 @@ 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;
Expand All @@ -292,11 +351,11 @@ 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;

Expand All @@ -320,18 +379,18 @@ 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;
Expand All @@ -341,7 +400,7 @@ 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);
}

Expand All @@ -353,12 +412,12 @@ static irqreturn_t max31335_handle_irq(int irq, void *dev_id)

mutex_lock(lock);

ret = regmap_read(max31335->regmap, MAX31335_STATUS1, &status);
ret = regmap_read(max31335->regmap, max31335->chip->int_status_reg, &status);
if (ret)
goto exit;

if (FIELD_GET(MAX31335_STATUS1_A1F, status)) {
ret = regmap_update_bits(max31335->regmap, MAX31335_STATUS1,
ret = regmap_update_bits(max31335->regmap, max31335->chip->int_status_reg,
MAX31335_STATUS1_A1F, 0);
if (ret)
goto exit;
Expand Down Expand Up @@ -414,7 +473,7 @@ 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));
Expand All @@ -428,7 +487,7 @@ 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;

Expand All @@ -454,29 +513,32 @@ static int max31335_clkout_set_rate(struct clk_hw *hw, unsigned long rate,
struct max31335_data *max31335 = clk_hw_to_max31335(hw);
unsigned int freq_mask;
int index;
int ret;

index = find_closest(rate, max31335_clkout_freq,
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);
ret = regmap_update_bits(max31335->regmap, max31335->chip->clkout_reg,
freq_mask, index);

return ret;
}

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,
MAX31335_RTC_CONFIG2_ENCLKO);
regmap_clear_bits(max31335->regmap, max31335->chip->clkout_reg,
MAX31335_RTC_CONFIG2_ENCLKO);
}

static int max31335_clkout_is_enabled(struct clk_hw *hw)
Expand All @@ -485,7 +547,7 @@ 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;

Expand All @@ -510,7 +572,7 @@ 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);
}
Expand All @@ -519,7 +581,7 @@ 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);
}
Expand All @@ -543,7 +605,7 @@ 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;
Expand Down Expand Up @@ -586,9 +648,10 @@ static int max31335_clkout_register(struct device *dev)
struct max31335_data *max31335 = dev_get_drvdata(dev);
int ret;

if (!device_property_present(dev, "#clock-cells"))
return regmap_clear_bits(max31335->regmap, MAX31335_RTC_CONFIG2,
MAX31335_RTC_CONFIG2_ENCLKO);
if (!device_property_present(dev, "#clock-cells")) {
regmap_clear_bits(max31335->regmap, max31335->chip->clkout_reg,
MAX31335_RTC_CONFIG2_ENCLKO);
}

max31335->clkout.init = &max31335_clk_init;

Expand Down Expand Up @@ -617,6 +680,7 @@ static int max31335_probe(struct i2c_client *client,
#if IS_REACHABLE(HWMON)
struct device *hwmon;
#endif
const void *match;
int ret;

max31335 = devm_kzalloc(&client->dev, sizeof(*max31335), GFP_KERNEL);
Expand All @@ -629,6 +693,16 @@ static int max31335_probe(struct i2c_client *client,

i2c_set_clientdata(client, max31335);

match = i2c_get_match_data(client);
if (match)
max31335->chip = match;
else if (id)
max31335->chip = (struct chip_desc *)id->driver_data;
else
return -ENODEV;

max31335->id = max31335->chip - chip;

max31335->rtc = devm_rtc_allocate_device(&client->dev);
if (IS_ERR(max31335->rtc))
return PTR_ERR(max31335->rtc);
Expand All @@ -651,6 +725,8 @@ static int max31335_probe(struct i2c_client *client,
dev_warn(&client->dev,
"unable to request IRQ, alarm max31335 disabled\n");
client->irq = 0;
} else {
max31335->irq = client->irq;
}
}

Expand All @@ -664,13 +740,15 @@ static int max31335_probe(struct i2c_client *client,
"cannot register rtc nvmem\n");

#if IS_REACHABLE(HWMON)
hwmon = devm_hwmon_device_register_with_info(&client->dev, client->name,
max31335,
&max31335_chip_info,
NULL);
if (IS_ERR(hwmon))
return dev_err_probe(&client->dev, PTR_ERR(hwmon),
"cannot register hwmon device\n");
if (max313xx->chip->temp_reg) {
hwmon = devm_hwmon_device_register_with_info(&client->dev, client->name,
max31335,
&max31335_chip_info,
NULL);
if (IS_ERR(hwmon))
return dev_err_probe(&client->dev, PTR_ERR(hwmon),
"cannot register hwmon device\n");
}
#endif

ret = max31335_trickle_charger_setup(&client->dev, max31335);
Expand All @@ -681,14 +759,16 @@ static int max31335_probe(struct i2c_client *client,
}

static const struct i2c_device_id max31335_id[] = {
{ "max31335", 0 },
{ "max31331", (kernel_ulong_t)&chip[ID_MAX31331] },
{ "max31335", (kernel_ulong_t)&chip[ID_MAX31335] },
{ }
};

MODULE_DEVICE_TABLE(i2c, max31335_id);

static const struct of_device_id max31335_of_match[] = {
{ .compatible = "adi,max31335" },
{ .compatible = "adi,max31331", .data = &chip[ID_MAX31331] },
{ .compatible = "adi,max31335", .data = &chip[ID_MAX31335] },
{ }
};

Expand All @@ -705,5 +785,6 @@ static struct i2c_driver max31335_driver = {
module_i2c_driver(max31335_driver);

MODULE_AUTHOR("Antoniu Miclaus <[email protected]>");
MODULE_AUTHOR("Saket Kumar Purwar <[email protected]>");
MODULE_DESCRIPTION("MAX31335 RTC driver");
MODULE_LICENSE("GPL");

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