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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller4 *5 * Copyright (C) 2008 Ira W. Snyder <iws@ovro.caltech.edu>6 *7 * This driver is based on the ds1621 and ina209 drivers.8 *9 * Datasheet:10 * http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1140,P19392,D1351711 */12 13#include <linux/kernel.h>14#include <linux/module.h>15#include <linux/init.h>16#include <linux/bitops.h>17#include <linux/err.h>18#include <linux/slab.h>19#include <linux/i2c.h>20#include <linux/hwmon.h>21#include <linux/hwmon-sysfs.h>22#include <linux/jiffies.h>23#include <linux/platform_data/ltc4245.h>24 25/* Here are names of the chip's registers (a.k.a. commands) */26enum ltc4245_cmd {27 LTC4245_STATUS = 0x00, /* readonly */28 LTC4245_ALERT = 0x01,29 LTC4245_CONTROL = 0x02,30 LTC4245_ON = 0x03,31 LTC4245_FAULT1 = 0x04,32 LTC4245_FAULT2 = 0x05,33 LTC4245_GPIO = 0x06,34 LTC4245_ADCADR = 0x07,35 36 LTC4245_12VIN = 0x10,37 LTC4245_12VSENSE = 0x11,38 LTC4245_12VOUT = 0x12,39 LTC4245_5VIN = 0x13,40 LTC4245_5VSENSE = 0x14,41 LTC4245_5VOUT = 0x15,42 LTC4245_3VIN = 0x16,43 LTC4245_3VSENSE = 0x17,44 LTC4245_3VOUT = 0x18,45 LTC4245_VEEIN = 0x19,46 LTC4245_VEESENSE = 0x1a,47 LTC4245_VEEOUT = 0x1b,48 LTC4245_GPIOADC = 0x1c,49};50 51struct ltc4245_data {52 struct i2c_client *client;53 54 struct mutex update_lock;55 bool valid;56 unsigned long last_updated; /* in jiffies */57 58 /* Control registers */59 u8 cregs[0x08];60 61 /* Voltage registers */62 u8 vregs[0x0d];63 64 /* GPIO ADC registers */65 bool use_extra_gpios;66 int gpios[3];67};68 69/*70 * Update the readings from the GPIO pins. If the driver has been configured to71 * sample all GPIO's as analog voltages, a round-robin sampling method is used.72 * Otherwise, only the configured GPIO pin is sampled.73 *74 * LOCKING: must hold data->update_lock75 */76static void ltc4245_update_gpios(struct device *dev)77{78 struct ltc4245_data *data = dev_get_drvdata(dev);79 struct i2c_client *client = data->client;80 u8 gpio_curr, gpio_next, gpio_reg;81 int i;82 83 /* no extra gpio support, we're basically done */84 if (!data->use_extra_gpios) {85 data->gpios[0] = data->vregs[LTC4245_GPIOADC - 0x10];86 return;87 }88 89 /*90 * If the last reading was too long ago, then we mark all old GPIO91 * readings as stale by setting them to -EAGAIN92 */93 if (time_after(jiffies, data->last_updated + 5 * HZ)) {94 for (i = 0; i < ARRAY_SIZE(data->gpios); i++)95 data->gpios[i] = -EAGAIN;96 }97 98 /*99 * Get the current GPIO pin100 *101 * The datasheet calls these GPIO[1-3], but we'll calculate the zero102 * based array index instead, and call them GPIO[0-2]. This is much103 * easier to think about.104 */105 gpio_curr = (data->cregs[LTC4245_GPIO] & 0xc0) >> 6;106 if (gpio_curr > 0)107 gpio_curr -= 1;108 109 /* Read the GPIO voltage from the GPIOADC register */110 data->gpios[gpio_curr] = data->vregs[LTC4245_GPIOADC - 0x10];111 112 /* Find the next GPIO pin to read */113 gpio_next = (gpio_curr + 1) % ARRAY_SIZE(data->gpios);114 115 /*116 * Calculate the correct setting for the GPIO register so it will117 * sample the next GPIO pin118 */119 gpio_reg = (data->cregs[LTC4245_GPIO] & 0x3f) | ((gpio_next + 1) << 6);120 121 /* Update the GPIO register */122 i2c_smbus_write_byte_data(client, LTC4245_GPIO, gpio_reg);123 124 /* Update saved data */125 data->cregs[LTC4245_GPIO] = gpio_reg;126}127 128static struct ltc4245_data *ltc4245_update_device(struct device *dev)129{130 struct ltc4245_data *data = dev_get_drvdata(dev);131 struct i2c_client *client = data->client;132 s32 val;133 int i;134 135 mutex_lock(&data->update_lock);136 137 if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {138 139 /* Read control registers -- 0x00 to 0x07 */140 for (i = 0; i < ARRAY_SIZE(data->cregs); i++) {141 val = i2c_smbus_read_byte_data(client, i);142 if (unlikely(val < 0))143 data->cregs[i] = 0;144 else145 data->cregs[i] = val;146 }147 148 /* Read voltage registers -- 0x10 to 0x1c */149 for (i = 0; i < ARRAY_SIZE(data->vregs); i++) {150 val = i2c_smbus_read_byte_data(client, i+0x10);151 if (unlikely(val < 0))152 data->vregs[i] = 0;153 else154 data->vregs[i] = val;155 }156 157 /* Update GPIO readings */158 ltc4245_update_gpios(dev);159 160 data->last_updated = jiffies;161 data->valid = true;162 }163 164 mutex_unlock(&data->update_lock);165 166 return data;167}168 169/* Return the voltage from the given register in millivolts */170static int ltc4245_get_voltage(struct device *dev, u8 reg)171{172 struct ltc4245_data *data = ltc4245_update_device(dev);173 const u8 regval = data->vregs[reg - 0x10];174 u32 voltage = 0;175 176 switch (reg) {177 case LTC4245_12VIN:178 case LTC4245_12VOUT:179 voltage = regval * 55;180 break;181 case LTC4245_5VIN:182 case LTC4245_5VOUT:183 voltage = regval * 22;184 break;185 case LTC4245_3VIN:186 case LTC4245_3VOUT:187 voltage = regval * 15;188 break;189 case LTC4245_VEEIN:190 case LTC4245_VEEOUT:191 voltage = regval * -55;192 break;193 case LTC4245_GPIOADC:194 voltage = regval * 10;195 break;196 default:197 /* If we get here, the developer messed up */198 WARN_ON_ONCE(1);199 break;200 }201 202 return voltage;203}204 205/* Return the current in the given sense register in milliAmperes */206static unsigned int ltc4245_get_current(struct device *dev, u8 reg)207{208 struct ltc4245_data *data = ltc4245_update_device(dev);209 const u8 regval = data->vregs[reg - 0x10];210 unsigned int voltage;211 unsigned int curr;212 213 /*214 * The strange looking conversions that follow are fixed-point215 * math, since we cannot do floating point in the kernel.216 *217 * Step 1: convert sense register to microVolts218 * Step 2: convert voltage to milliAmperes219 *220 * If you play around with the V=IR equation, you come up with221 * the following: X uV / Y mOhm == Z mA222 *223 * With the resistors that are fractions of a milliOhm, we multiply224 * the voltage and resistance by 10, to shift the decimal point.225 * Now we can use the normal division operator again.226 */227 228 switch (reg) {229 case LTC4245_12VSENSE:230 voltage = regval * 250; /* voltage in uV */231 curr = voltage / 50; /* sense resistor 50 mOhm */232 break;233 case LTC4245_5VSENSE:234 voltage = regval * 125; /* voltage in uV */235 curr = (voltage * 10) / 35; /* sense resistor 3.5 mOhm */236 break;237 case LTC4245_3VSENSE:238 voltage = regval * 125; /* voltage in uV */239 curr = (voltage * 10) / 25; /* sense resistor 2.5 mOhm */240 break;241 case LTC4245_VEESENSE:242 voltage = regval * 250; /* voltage in uV */243 curr = voltage / 100; /* sense resistor 100 mOhm */244 break;245 default:246 /* If we get here, the developer messed up */247 WARN_ON_ONCE(1);248 curr = 0;249 break;250 }251 252 return curr;253}254 255/* Map from voltage channel index to voltage register */256 257static const s8 ltc4245_in_regs[] = {258 LTC4245_12VIN, LTC4245_5VIN, LTC4245_3VIN, LTC4245_VEEIN,259 LTC4245_12VOUT, LTC4245_5VOUT, LTC4245_3VOUT, LTC4245_VEEOUT,260};261 262/* Map from current channel index to current register */263 264static const s8 ltc4245_curr_regs[] = {265 LTC4245_12VSENSE, LTC4245_5VSENSE, LTC4245_3VSENSE, LTC4245_VEESENSE,266};267 268static int ltc4245_read_curr(struct device *dev, u32 attr, int channel,269 long *val)270{271 struct ltc4245_data *data = ltc4245_update_device(dev);272 273 switch (attr) {274 case hwmon_curr_input:275 *val = ltc4245_get_current(dev, ltc4245_curr_regs[channel]);276 return 0;277 case hwmon_curr_max_alarm:278 *val = !!(data->cregs[LTC4245_FAULT1] & BIT(channel + 4));279 return 0;280 default:281 return -EOPNOTSUPP;282 }283}284 285static int ltc4245_read_in(struct device *dev, u32 attr, int channel, long *val)286{287 struct ltc4245_data *data = ltc4245_update_device(dev);288 289 switch (attr) {290 case hwmon_in_input:291 if (channel < 8) {292 *val = ltc4245_get_voltage(dev,293 ltc4245_in_regs[channel]);294 } else {295 int regval = data->gpios[channel - 8];296 297 if (regval < 0)298 return regval;299 *val = regval * 10;300 }301 return 0;302 case hwmon_in_min_alarm:303 if (channel < 4)304 *val = !!(data->cregs[LTC4245_FAULT1] & BIT(channel));305 else306 *val = !!(data->cregs[LTC4245_FAULT2] &307 BIT(channel - 4));308 return 0;309 default:310 return -EOPNOTSUPP;311 }312}313 314static int ltc4245_read_power(struct device *dev, u32 attr, int channel,315 long *val)316{317 unsigned long curr;318 long voltage;319 320 switch (attr) {321 case hwmon_power_input:322 (void)ltc4245_update_device(dev);323 curr = ltc4245_get_current(dev, ltc4245_curr_regs[channel]);324 voltage = ltc4245_get_voltage(dev, ltc4245_in_regs[channel]);325 *val = abs(curr * voltage);326 return 0;327 default:328 return -EOPNOTSUPP;329 }330}331 332static int ltc4245_read(struct device *dev, enum hwmon_sensor_types type,333 u32 attr, int channel, long *val)334{335 336 switch (type) {337 case hwmon_curr:338 return ltc4245_read_curr(dev, attr, channel, val);339 case hwmon_power:340 return ltc4245_read_power(dev, attr, channel, val);341 case hwmon_in:342 return ltc4245_read_in(dev, attr, channel - 1, val);343 default:344 return -EOPNOTSUPP;345 }346}347 348static umode_t ltc4245_is_visible(const void *_data,349 enum hwmon_sensor_types type,350 u32 attr, int channel)351{352 const struct ltc4245_data *data = _data;353 354 switch (type) {355 case hwmon_in:356 if (channel == 0)357 return 0;358 switch (attr) {359 case hwmon_in_input:360 if (channel > 9 && !data->use_extra_gpios)361 return 0;362 return 0444;363 case hwmon_in_min_alarm:364 if (channel > 8)365 return 0;366 return 0444;367 default:368 return 0;369 }370 case hwmon_curr:371 switch (attr) {372 case hwmon_curr_input:373 case hwmon_curr_max_alarm:374 return 0444;375 default:376 return 0;377 }378 case hwmon_power:379 switch (attr) {380 case hwmon_power_input:381 return 0444;382 default:383 return 0;384 }385 default:386 return 0;387 }388}389 390static const struct hwmon_channel_info * const ltc4245_info[] = {391 HWMON_CHANNEL_INFO(in,392 HWMON_I_INPUT,393 HWMON_I_INPUT | HWMON_I_MIN_ALARM,394 HWMON_I_INPUT | HWMON_I_MIN_ALARM,395 HWMON_I_INPUT | HWMON_I_MIN_ALARM,396 HWMON_I_INPUT | HWMON_I_MIN_ALARM,397 HWMON_I_INPUT | HWMON_I_MIN_ALARM,398 HWMON_I_INPUT | HWMON_I_MIN_ALARM,399 HWMON_I_INPUT | HWMON_I_MIN_ALARM,400 HWMON_I_INPUT | HWMON_I_MIN_ALARM,401 HWMON_I_INPUT,402 HWMON_I_INPUT,403 HWMON_I_INPUT),404 HWMON_CHANNEL_INFO(curr,405 HWMON_C_INPUT | HWMON_C_MAX_ALARM,406 HWMON_C_INPUT | HWMON_C_MAX_ALARM,407 HWMON_C_INPUT | HWMON_C_MAX_ALARM,408 HWMON_C_INPUT | HWMON_C_MAX_ALARM),409 HWMON_CHANNEL_INFO(power,410 HWMON_P_INPUT,411 HWMON_P_INPUT,412 HWMON_P_INPUT,413 HWMON_P_INPUT),414 NULL415};416 417static const struct hwmon_ops ltc4245_hwmon_ops = {418 .is_visible = ltc4245_is_visible,419 .read = ltc4245_read,420};421 422static const struct hwmon_chip_info ltc4245_chip_info = {423 .ops = <c4245_hwmon_ops,424 .info = ltc4245_info,425};426 427static bool ltc4245_use_extra_gpios(struct i2c_client *client)428{429 struct ltc4245_platform_data *pdata = dev_get_platdata(&client->dev);430 struct device_node *np = client->dev.of_node;431 432 /* prefer platform data */433 if (pdata)434 return pdata->use_extra_gpios;435 436 /* fallback on OF */437 if (of_property_read_bool(np, "ltc4245,use-extra-gpios"))438 return true;439 440 return false;441}442 443static int ltc4245_probe(struct i2c_client *client)444{445 struct i2c_adapter *adapter = client->adapter;446 struct ltc4245_data *data;447 struct device *hwmon_dev;448 449 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))450 return -ENODEV;451 452 data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);453 if (!data)454 return -ENOMEM;455 456 data->client = client;457 mutex_init(&data->update_lock);458 data->use_extra_gpios = ltc4245_use_extra_gpios(client);459 460 /* Initialize the LTC4245 chip */461 i2c_smbus_write_byte_data(client, LTC4245_FAULT1, 0x00);462 i2c_smbus_write_byte_data(client, LTC4245_FAULT2, 0x00);463 464 hwmon_dev = devm_hwmon_device_register_with_info(&client->dev,465 client->name, data,466 <c4245_chip_info,467 NULL);468 return PTR_ERR_OR_ZERO(hwmon_dev);469}470 471static const struct i2c_device_id ltc4245_id[] = {472 { "ltc4245" },473 { }474};475MODULE_DEVICE_TABLE(i2c, ltc4245_id);476 477/* This is the driver that will be inserted */478static struct i2c_driver ltc4245_driver = {479 .driver = {480 .name = "ltc4245",481 },482 .probe = ltc4245_probe,483 .id_table = ltc4245_id,484};485 486module_i2c_driver(ltc4245_driver);487 488MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");489MODULE_DESCRIPTION("LTC4245 driver");490MODULE_LICENSE("GPL");491