drivers/hwmon/ltc4245.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller
0004  *
0005  * Copyright (C) 2008 Ira W. Snyder <iws@ovro.caltech.edu>
0006  *
0007  * This driver is based on the ds1621 and ina209 drivers.
0008  *
0009  * Datasheet:
0010  * http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1140,P19392,D13517
0011  */
0012
0013 #include <linux/kernel.h>
0014 #include <linux/module.h>
0015 #include <linux/init.h>
0016 #include <linux/bitops.h>
0017 #include <linux/err.h>
0018 #include <linux/slab.h>
0019 #include <linux/i2c.h>
0020 #include <linux/hwmon.h>
0021 #include <linux/hwmon-sysfs.h>
0022 #include <linux/jiffies.h>
0023 #include <linux/platform_data/ltc4245.h>
0024
0025 /* Here are names of the chip's registers (a.k.a. commands) */
0026 enum ltc4245_cmd {
0027     LTC4245_STATUS          = 0x00, /* readonly */
0028     LTC4245_ALERT           = 0x01,
0029     LTC4245_CONTROL         = 0x02,
0030     LTC4245_ON          = 0x03,
0031     LTC4245_FAULT1          = 0x04,
0032     LTC4245_FAULT2          = 0x05,
0033     LTC4245_GPIO            = 0x06,
0034     LTC4245_ADCADR          = 0x07,
0035
0036     LTC4245_12VIN           = 0x10,
0037     LTC4245_12VSENSE        = 0x11,
0038     LTC4245_12VOUT          = 0x12,
0039     LTC4245_5VIN            = 0x13,
0040     LTC4245_5VSENSE         = 0x14,
0041     LTC4245_5VOUT           = 0x15,
0042     LTC4245_3VIN            = 0x16,
0043     LTC4245_3VSENSE         = 0x17,
0044     LTC4245_3VOUT           = 0x18,
0045     LTC4245_VEEIN           = 0x19,
0046     LTC4245_VEESENSE        = 0x1a,
0047     LTC4245_VEEOUT          = 0x1b,
0048     LTC4245_GPIOADC         = 0x1c,
0049 };
0050
0051 struct ltc4245_data {
0052     struct i2c_client *client;
0053
0054     struct mutex update_lock;
0055     bool valid;
0056     unsigned long last_updated; /* in jiffies */
0057
0058     /* Control registers */
0059     u8 cregs[0x08];
0060
0061     /* Voltage registers */
0062     u8 vregs[0x0d];
0063
0064     /* GPIO ADC registers */
0065     bool use_extra_gpios;
0066     int gpios[3];
0067 };
0068
0069 /*
0070  * Update the readings from the GPIO pins. If the driver has been configured to
0071  * sample all GPIO's as analog voltages, a round-robin sampling method is used.
0072  * Otherwise, only the configured GPIO pin is sampled.
0073  *
0074  * LOCKING: must hold data->update_lock
0075  */
0076 static void ltc4245_update_gpios(struct device *dev)
0077 {
0078     struct ltc4245_data *data = dev_get_drvdata(dev);
0079     struct i2c_client *client = data->client;
0080     u8 gpio_curr, gpio_next, gpio_reg;
0081     int i;
0082
0083     /* no extra gpio support, we're basically done */
0084     if (!data->use_extra_gpios) {
0085         data->gpios[0] = data->vregs[LTC4245_GPIOADC - 0x10];
0086         return;
0087     }
0088
0089     /*
0090      * If the last reading was too long ago, then we mark all old GPIO
0091      * readings as stale by setting them to -EAGAIN
0092      */
0093     if (time_after(jiffies, data->last_updated + 5 * HZ)) {
0094         for (i = 0; i < ARRAY_SIZE(data->gpios); i++)
0095             data->gpios[i] = -EAGAIN;
0096     }
0097
0098     /*
0099      * Get the current GPIO pin
0100      *
0101      * The datasheet calls these GPIO[1-3], but we'll calculate the zero
0102      * based array index instead, and call them GPIO[0-2]. This is much
0103      * easier to think about.
0104      */
0105     gpio_curr = (data->cregs[LTC4245_GPIO] & 0xc0) >> 6;
0106     if (gpio_curr > 0)
0107         gpio_curr -= 1;
0108
0109     /* Read the GPIO voltage from the GPIOADC register */
0110     data->gpios[gpio_curr] = data->vregs[LTC4245_GPIOADC - 0x10];
0111
0112     /* Find the next GPIO pin to read */
0113     gpio_next = (gpio_curr + 1) % ARRAY_SIZE(data->gpios);
0114
0115     /*
0116      * Calculate the correct setting for the GPIO register so it will
0117      * sample the next GPIO pin
0118      */
0119     gpio_reg = (data->cregs[LTC4245_GPIO] & 0x3f) | ((gpio_next + 1) << 6);
0120
0121     /* Update the GPIO register */
0122     i2c_smbus_write_byte_data(client, LTC4245_GPIO, gpio_reg);
0123
0124     /* Update saved data */
0125     data->cregs[LTC4245_GPIO] = gpio_reg;
0126 }
0127
0128 static struct ltc4245_data *ltc4245_update_device(struct device *dev)
0129 {
0130     struct ltc4245_data *data = dev_get_drvdata(dev);
0131     struct i2c_client *client = data->client;
0132     s32 val;
0133     int i;
0134
0135     mutex_lock(&data->update_lock);
0136
0137     if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
0138
0139         /* Read control registers -- 0x00 to 0x07 */
0140         for (i = 0; i < ARRAY_SIZE(data->cregs); i++) {
0141             val = i2c_smbus_read_byte_data(client, i);
0142             if (unlikely(val < 0))
0143                 data->cregs[i] = 0;
0144             else
0145                 data->cregs[i] = val;
0146         }
0147
0148         /* Read voltage registers -- 0x10 to 0x1c */
0149         for (i = 0; i < ARRAY_SIZE(data->vregs); i++) {
0150             val = i2c_smbus_read_byte_data(client, i+0x10);
0151             if (unlikely(val < 0))
0152                 data->vregs[i] = 0;
0153             else
0154                 data->vregs[i] = val;
0155         }
0156
0157         /* Update GPIO readings */
0158         ltc4245_update_gpios(dev);
0159
0160         data->last_updated = jiffies;
0161         data->valid = true;
0162     }
0163
0164     mutex_unlock(&data->update_lock);
0165
0166     return data;
0167 }
0168
0169 /* Return the voltage from the given register in millivolts */
0170 static int ltc4245_get_voltage(struct device *dev, u8 reg)
0171 {
0172     struct ltc4245_data *data = ltc4245_update_device(dev);
0173     const u8 regval = data->vregs[reg - 0x10];
0174     u32 voltage = 0;
0175
0176     switch (reg) {
0177     case LTC4245_12VIN:
0178     case LTC4245_12VOUT:
0179         voltage = regval * 55;
0180         break;
0181     case LTC4245_5VIN:
0182     case LTC4245_5VOUT:
0183         voltage = regval * 22;
0184         break;
0185     case LTC4245_3VIN:
0186     case LTC4245_3VOUT:
0187         voltage = regval * 15;
0188         break;
0189     case LTC4245_VEEIN:
0190     case LTC4245_VEEOUT:
0191         voltage = regval * -55;
0192         break;
0193     case LTC4245_GPIOADC:
0194         voltage = regval * 10;
0195         break;
0196     default:
0197         /* If we get here, the developer messed up */
0198         WARN_ON_ONCE(1);
0199         break;
0200     }
0201
0202     return voltage;
0203 }
0204
0205 /* Return the current in the given sense register in milliAmperes */
0206 static unsigned int ltc4245_get_current(struct device *dev, u8 reg)
0207 {
0208     struct ltc4245_data *data = ltc4245_update_device(dev);
0209     const u8 regval = data->vregs[reg - 0x10];
0210     unsigned int voltage;
0211     unsigned int curr;
0212
0213     /*
0214      * The strange looking conversions that follow are fixed-point
0215      * math, since we cannot do floating point in the kernel.
0216      *
0217      * Step 1: convert sense register to microVolts
0218      * Step 2: convert voltage to milliAmperes
0219      *
0220      * If you play around with the V=IR equation, you come up with
0221      * the following: X uV / Y mOhm == Z mA
0222      *
0223      * With the resistors that are fractions of a milliOhm, we multiply
0224      * the voltage and resistance by 10, to shift the decimal point.
0225      * Now we can use the normal division operator again.
0226      */
0227
0228     switch (reg) {
0229     case LTC4245_12VSENSE:
0230         voltage = regval * 250; /* voltage in uV */
0231         curr = voltage / 50; /* sense resistor 50 mOhm */
0232         break;
0233     case LTC4245_5VSENSE:
0234         voltage = regval * 125; /* voltage in uV */
0235         curr = (voltage * 10) / 35; /* sense resistor 3.5 mOhm */
0236         break;
0237     case LTC4245_3VSENSE:
0238         voltage = regval * 125; /* voltage in uV */
0239         curr = (voltage * 10) / 25; /* sense resistor 2.5 mOhm */
0240         break;
0241     case LTC4245_VEESENSE:
0242         voltage = regval * 250; /* voltage in uV */
0243         curr = voltage / 100; /* sense resistor 100 mOhm */
0244         break;
0245     default:
0246         /* If we get here, the developer messed up */
0247         WARN_ON_ONCE(1);
0248         curr = 0;
0249         break;
0250     }
0251
0252     return curr;
0253 }
0254
0255 /* Map from voltage channel index to voltage register */
0256
0257 static const s8 ltc4245_in_regs[] = {
0258     LTC4245_12VIN, LTC4245_5VIN, LTC4245_3VIN, LTC4245_VEEIN,
0259     LTC4245_12VOUT, LTC4245_5VOUT, LTC4245_3VOUT, LTC4245_VEEOUT,
0260 };
0261
0262 /* Map from current channel index to current register */
0263
0264 static const s8 ltc4245_curr_regs[] = {
0265     LTC4245_12VSENSE, LTC4245_5VSENSE, LTC4245_3VSENSE, LTC4245_VEESENSE,
0266 };
0267
0268 static int ltc4245_read_curr(struct device *dev, u32 attr, int channel,
0269                  long *val)
0270 {
0271     struct ltc4245_data *data = ltc4245_update_device(dev);
0272
0273     switch (attr) {
0274     case hwmon_curr_input:
0275         *val = ltc4245_get_current(dev, ltc4245_curr_regs[channel]);
0276         return 0;
0277     case hwmon_curr_max_alarm:
0278         *val = !!(data->cregs[LTC4245_FAULT1] & BIT(channel + 4));
0279         return 0;
0280     default:
0281         return -EOPNOTSUPP;
0282     }
0283 }
0284
0285 static int ltc4245_read_in(struct device *dev, u32 attr, int channel, long *val)
0286 {
0287     struct ltc4245_data *data = ltc4245_update_device(dev);
0288
0289     switch (attr) {
0290     case hwmon_in_input:
0291         if (channel < 8) {
0292             *val = ltc4245_get_voltage(dev,
0293                         ltc4245_in_regs[channel]);
0294         } else {
0295             int regval = data->gpios[channel - 8];
0296
0297             if (regval < 0)
0298                 return regval;
0299             *val = regval * 10;
0300         }
0301         return 0;
0302     case hwmon_in_min_alarm:
0303         if (channel < 4)
0304             *val = !!(data->cregs[LTC4245_FAULT1] & BIT(channel));
0305         else
0306             *val = !!(data->cregs[LTC4245_FAULT2] &
0307                   BIT(channel - 4));
0308         return 0;
0309     default:
0310         return -EOPNOTSUPP;
0311     }
0312 }
0313
0314 static int ltc4245_read_power(struct device *dev, u32 attr, int channel,
0315                   long *val)
0316 {
0317     unsigned long curr;
0318     long voltage;
0319
0320     switch (attr) {
0321     case hwmon_power_input:
0322         (void)ltc4245_update_device(dev);
0323         curr = ltc4245_get_current(dev, ltc4245_curr_regs[channel]);
0324         voltage = ltc4245_get_voltage(dev, ltc4245_in_regs[channel]);
0325         *val = abs(curr * voltage);
0326         return 0;
0327     default:
0328         return -EOPNOTSUPP;
0329     }
0330 }
0331
0332 static int ltc4245_read(struct device *dev, enum hwmon_sensor_types type,
0333             u32 attr, int channel, long *val)
0334 {
0335
0336     switch (type) {
0337     case hwmon_curr:
0338         return ltc4245_read_curr(dev, attr, channel, val);
0339     case hwmon_power:
0340         return ltc4245_read_power(dev, attr, channel, val);
0341     case hwmon_in:
0342         return ltc4245_read_in(dev, attr, channel - 1, val);
0343     default:
0344         return -EOPNOTSUPP;
0345     }
0346 }
0347
0348 static umode_t ltc4245_is_visible(const void *_data,
0349                   enum hwmon_sensor_types type,
0350                   u32 attr, int channel)
0351 {
0352     const struct ltc4245_data *data = _data;
0353
0354     switch (type) {
0355     case hwmon_in:
0356         if (channel == 0)
0357             return 0;
0358         switch (attr) {
0359         case hwmon_in_input:
0360             if (channel > 9 && !data->use_extra_gpios)
0361                 return 0;
0362             return 0444;
0363         case hwmon_in_min_alarm:
0364             if (channel > 8)
0365                 return 0;
0366             return 0444;
0367         default:
0368             return 0;
0369         }
0370     case hwmon_curr:
0371         switch (attr) {
0372         case hwmon_curr_input:
0373         case hwmon_curr_max_alarm:
0374             return 0444;
0375         default:
0376             return 0;
0377         }
0378     case hwmon_power:
0379         switch (attr) {
0380         case hwmon_power_input:
0381             return 0444;
0382         default:
0383             return 0;
0384         }
0385     default:
0386         return 0;
0387     }
0388 }
0389
0390 static const struct hwmon_channel_info *ltc4245_info[] = {
0391     HWMON_CHANNEL_INFO(in,
0392                HWMON_I_INPUT,
0393                HWMON_I_INPUT | HWMON_I_MIN_ALARM,
0394                HWMON_I_INPUT | HWMON_I_MIN_ALARM,
0395                HWMON_I_INPUT | HWMON_I_MIN_ALARM,
0396                HWMON_I_INPUT | HWMON_I_MIN_ALARM,
0397                HWMON_I_INPUT | HWMON_I_MIN_ALARM,
0398                HWMON_I_INPUT | HWMON_I_MIN_ALARM,
0399                HWMON_I_INPUT | HWMON_I_MIN_ALARM,
0400                HWMON_I_INPUT | HWMON_I_MIN_ALARM,
0401                HWMON_I_INPUT,
0402                HWMON_I_INPUT,
0403                HWMON_I_INPUT),
0404     HWMON_CHANNEL_INFO(curr,
0405                HWMON_C_INPUT | HWMON_C_MAX_ALARM,
0406                HWMON_C_INPUT | HWMON_C_MAX_ALARM,
0407                HWMON_C_INPUT | HWMON_C_MAX_ALARM,
0408                HWMON_C_INPUT | HWMON_C_MAX_ALARM),
0409     HWMON_CHANNEL_INFO(power,
0410                HWMON_P_INPUT,
0411                HWMON_P_INPUT,
0412                HWMON_P_INPUT,
0413                HWMON_P_INPUT),
0414     NULL
0415 };
0416
0417 static const struct hwmon_ops ltc4245_hwmon_ops = {
0418     .is_visible = ltc4245_is_visible,
0419     .read = ltc4245_read,
0420 };
0421
0422 static const struct hwmon_chip_info ltc4245_chip_info = {
0423     .ops = &ltc4245_hwmon_ops,
0424     .info = ltc4245_info,
0425 };
0426
0427 static bool ltc4245_use_extra_gpios(struct i2c_client *client)
0428 {
0429     struct ltc4245_platform_data *pdata = dev_get_platdata(&client->dev);
0430     struct device_node *np = client->dev.of_node;
0431
0432     /* prefer platform data */
0433     if (pdata)
0434         return pdata->use_extra_gpios;
0435
0436     /* fallback on OF */
0437     if (of_find_property(np, "ltc4245,use-extra-gpios", NULL))
0438         return true;
0439
0440     return false;
0441 }
0442
0443 static int ltc4245_probe(struct i2c_client *client)
0444 {
0445     struct i2c_adapter *adapter = client->adapter;
0446     struct ltc4245_data *data;
0447     struct device *hwmon_dev;
0448
0449     if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
0450         return -ENODEV;
0451
0452     data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
0453     if (!data)
0454         return -ENOMEM;
0455
0456     data->client = client;
0457     mutex_init(&data->update_lock);
0458     data->use_extra_gpios = ltc4245_use_extra_gpios(client);
0459
0460     /* Initialize the LTC4245 chip */
0461     i2c_smbus_write_byte_data(client, LTC4245_FAULT1, 0x00);
0462     i2c_smbus_write_byte_data(client, LTC4245_FAULT2, 0x00);
0463
0464     hwmon_dev = devm_hwmon_device_register_with_info(&client->dev,
0465                              client->name, data,
0466                              &ltc4245_chip_info,
0467                              NULL);
0468     return PTR_ERR_OR_ZERO(hwmon_dev);
0469 }
0470
0471 static const struct i2c_device_id ltc4245_id[] = {
0472     { "ltc4245", 0 },
0473     { }
0474 };
0475 MODULE_DEVICE_TABLE(i2c, ltc4245_id);
0476
0477 /* This is the driver that will be inserted */
0478 static struct i2c_driver ltc4245_driver = {
0479     .driver = {
0480         .name   = "ltc4245",
0481     },
0482     .probe_new  = ltc4245_probe,
0483     .id_table   = ltc4245_id,
0484 };
0485
0486 module_i2c_driver(ltc4245_driver);
0487
0488 MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
0489 MODULE_DESCRIPTION("LTC4245 driver");
0490 MODULE_LICENSE("GPL");