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486 lines
13 KiB
486 lines
13 KiB
// SPDX-License-Identifier: GPL-2.0+ |
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/* |
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* Battery monitor driver for the uPI uG3105 battery monitor |
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* |
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* Note the uG3105 is not a full-featured autonomous fuel-gauge. Instead it is |
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* expected to be use in combination with some always on microcontroller reading |
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* its coulomb-counter before it can wrap (must be read every 400 seconds!). |
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* |
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* Since Linux does not monitor coulomb-counter changes while the device |
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* is off or suspended, the coulomb counter is not used atm. |
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* |
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* Possible improvements: |
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* 1. Activate commented out total_coulomb_count code |
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* 2. Reset total_coulomb_count val to 0 when the battery is as good as empty |
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* and remember that we did this (and clear the flag for this on susp/resume) |
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* 3. When the battery is full check if the flag that we set total_coulomb_count |
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* to when the battery was empty is set. If so we now know the capacity, |
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* not the design, but actual capacity, of the battery |
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* 4. Add some mechanism (needs userspace help, or maybe use efivar?) to remember |
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* the actual capacity of the battery over reboots |
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* 5. When we know the actual capacity at probe time, add energy_now and |
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* energy_full attributes. Guess boot + resume energy_now value based on ocv |
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* and then use total_coulomb_count to report energy_now over time, resetting |
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* things to adjust for drift when empty/full. This should give more accurate |
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* readings, esp. in the 30-70% range and allow userspace to estimate time |
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* remaining till empty/full |
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* 6. Maybe unregister + reregister the psy device when we learn the actual |
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* capacity during run-time ? |
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* |
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* The above will also require some sort of mwh_per_unit calculation. Testing |
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* has shown that an estimated 7404mWh increase of the battery's energy results |
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* in a total_coulomb_count increase of 3277 units with a 5 milli-ohm sense R. |
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* |
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* Copyright (C) 2021 Hans de Goede <[email protected]> |
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*/ |
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#include <linux/devm-helpers.h> |
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#include <linux/module.h> |
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#include <linux/mutex.h> |
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#include <linux/slab.h> |
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#include <linux/i2c.h> |
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#include <linux/mod_devicetable.h> |
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#include <linux/power_supply.h> |
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#include <linux/workqueue.h> |
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#define UG3105_MOV_AVG_WINDOW 8 |
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#define UG3105_INIT_POLL_TIME (5 * HZ) |
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#define UG3105_POLL_TIME (30 * HZ) |
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#define UG3105_SETTLE_TIME (1 * HZ) |
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#define UG3105_INIT_POLL_COUNT 30 |
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#define UG3105_REG_MODE 0x00 |
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#define UG3105_REG_CTRL1 0x01 |
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#define UG3105_REG_COULOMB_CNT 0x02 |
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#define UG3105_REG_BAT_VOLT 0x08 |
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#define UG3105_REG_BAT_CURR 0x0c |
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#define UG3105_MODE_STANDBY 0x00 |
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#define UG3105_MODE_RUN 0x10 |
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#define UG3105_CTRL1_RESET_COULOMB_CNT 0x03 |
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#define UG3105_CURR_HYST_UA 65000 |
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#define UG3105_LOW_BAT_UV 3700000 |
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#define UG3105_FULL_BAT_HYST_UV 38000 |
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struct ug3105_chip { |
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struct i2c_client *client; |
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struct power_supply *psy; |
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struct power_supply_battery_info *info; |
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struct delayed_work work; |
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struct mutex lock; |
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int ocv[UG3105_MOV_AVG_WINDOW]; /* micro-volt */ |
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int intern_res[UG3105_MOV_AVG_WINDOW]; /* milli-ohm */ |
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int poll_count; |
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int ocv_avg_index; |
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int ocv_avg; /* micro-volt */ |
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int intern_res_poll_count; |
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int intern_res_avg_index; |
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int intern_res_avg; /* milli-ohm */ |
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int volt; /* micro-volt */ |
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int curr; /* micro-ampere */ |
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int total_coulomb_count; |
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int uv_per_unit; |
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int ua_per_unit; |
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int status; |
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int capacity; |
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bool supplied; |
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}; |
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static int ug3105_read_word(struct i2c_client *client, u8 reg) |
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{ |
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int val; |
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val = i2c_smbus_read_word_data(client, reg); |
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if (val < 0) |
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dev_err(&client->dev, "Error reading reg 0x%02x\n", reg); |
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return val; |
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} |
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static int ug3105_get_status(struct ug3105_chip *chip) |
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{ |
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int full = chip->info->constant_charge_voltage_max_uv - UG3105_FULL_BAT_HYST_UV; |
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if (chip->curr > UG3105_CURR_HYST_UA) |
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return POWER_SUPPLY_STATUS_CHARGING; |
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if (chip->curr < -UG3105_CURR_HYST_UA) |
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return POWER_SUPPLY_STATUS_DISCHARGING; |
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if (chip->supplied && chip->ocv_avg > full) |
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return POWER_SUPPLY_STATUS_FULL; |
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return POWER_SUPPLY_STATUS_NOT_CHARGING; |
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} |
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static int ug3105_get_capacity(struct ug3105_chip *chip) |
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{ |
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/* |
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* OCV voltages in uV for 0-110% in 5% increments, the 100-110% is |
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* for LiPo HV (High-Voltage) bateries which can go up to 4.35V |
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* instead of the usual 4.2V. |
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*/ |
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static const int ocv_capacity_tbl[23] = { |
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3350000, |
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3610000, |
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3690000, |
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3710000, |
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3730000, |
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3750000, |
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3770000, |
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3786667, |
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3803333, |
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3820000, |
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3836667, |
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3853333, |
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3870000, |
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3907500, |
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3945000, |
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3982500, |
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4020000, |
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4075000, |
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4110000, |
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4150000, |
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4200000, |
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4250000, |
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4300000, |
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}; |
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int i, ocv_diff, ocv_step; |
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if (chip->ocv_avg < ocv_capacity_tbl[0]) |
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return 0; |
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if (chip->status == POWER_SUPPLY_STATUS_FULL) |
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return 100; |
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for (i = 1; i < ARRAY_SIZE(ocv_capacity_tbl); i++) { |
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if (chip->ocv_avg > ocv_capacity_tbl[i]) |
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continue; |
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ocv_diff = ocv_capacity_tbl[i] - chip->ocv_avg; |
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ocv_step = ocv_capacity_tbl[i] - ocv_capacity_tbl[i - 1]; |
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/* scale 0-110% down to 0-100% for LiPo HV */ |
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if (chip->info->constant_charge_voltage_max_uv >= 4300000) |
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return (i * 500 - ocv_diff * 500 / ocv_step) / 110; |
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else |
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return i * 5 - ocv_diff * 5 / ocv_step; |
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} |
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return 100; |
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} |
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static void ug3105_work(struct work_struct *work) |
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{ |
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struct ug3105_chip *chip = container_of(work, struct ug3105_chip, |
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work.work); |
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int i, val, curr_diff, volt_diff, res, win_size; |
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bool prev_supplied = chip->supplied; |
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int prev_status = chip->status; |
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int prev_volt = chip->volt; |
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int prev_curr = chip->curr; |
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struct power_supply *psy; |
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mutex_lock(&chip->lock); |
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psy = chip->psy; |
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if (!psy) |
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goto out; |
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val = ug3105_read_word(chip->client, UG3105_REG_BAT_VOLT); |
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if (val < 0) |
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goto out; |
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chip->volt = val * chip->uv_per_unit; |
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val = ug3105_read_word(chip->client, UG3105_REG_BAT_CURR); |
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if (val < 0) |
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goto out; |
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chip->curr = (s16)val * chip->ua_per_unit; |
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chip->ocv[chip->ocv_avg_index] = |
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chip->volt - chip->curr * chip->intern_res_avg / 1000; |
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chip->ocv_avg_index = (chip->ocv_avg_index + 1) % UG3105_MOV_AVG_WINDOW; |
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chip->poll_count++; |
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/* |
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* See possible improvements comment above. |
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* |
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* Read + reset coulomb counter every 10 polls (every 300 seconds) |
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* if ((chip->poll_count % 10) == 0) { |
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* val = ug3105_read_word(chip->client, UG3105_REG_COULOMB_CNT); |
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* if (val < 0) |
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* goto out; |
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* |
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* i2c_smbus_write_byte_data(chip->client, UG3105_REG_CTRL1, |
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* UG3105_CTRL1_RESET_COULOMB_CNT); |
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* |
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* chip->total_coulomb_count += (s16)val; |
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* dev_dbg(&chip->client->dev, "coulomb count %d total %d\n", |
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* (s16)val, chip->total_coulomb_count); |
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* } |
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*/ |
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chip->ocv_avg = 0; |
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win_size = min(chip->poll_count, UG3105_MOV_AVG_WINDOW); |
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for (i = 0; i < win_size; i++) |
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chip->ocv_avg += chip->ocv[i]; |
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chip->ocv_avg /= win_size; |
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chip->supplied = power_supply_am_i_supplied(psy); |
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chip->status = ug3105_get_status(chip); |
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chip->capacity = ug3105_get_capacity(chip); |
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/* |
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* Skip internal resistance calc on charger [un]plug and |
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* when the battery is almost empty (voltage low). |
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*/ |
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if (chip->supplied != prev_supplied || |
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chip->volt < UG3105_LOW_BAT_UV || |
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chip->poll_count < 2) |
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goto out; |
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/* |
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* Assuming that the OCV voltage does not change significantly |
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* between 2 polls, then we can calculate the internal resistance |
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* on a significant current change by attributing all voltage |
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* change between the 2 readings to the internal resistance. |
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*/ |
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curr_diff = abs(chip->curr - prev_curr); |
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if (curr_diff < UG3105_CURR_HYST_UA) |
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goto out; |
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volt_diff = abs(chip->volt - prev_volt); |
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res = volt_diff * 1000 / curr_diff; |
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if ((res < (chip->intern_res_avg * 2 / 3)) || |
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(res > (chip->intern_res_avg * 4 / 3))) { |
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dev_dbg(&chip->client->dev, "Ignoring outlier internal resistance %d mOhm\n", res); |
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goto out; |
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} |
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dev_dbg(&chip->client->dev, "Internal resistance %d mOhm\n", res); |
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chip->intern_res[chip->intern_res_avg_index] = res; |
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chip->intern_res_avg_index = (chip->intern_res_avg_index + 1) % UG3105_MOV_AVG_WINDOW; |
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chip->intern_res_poll_count++; |
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chip->intern_res_avg = 0; |
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win_size = min(chip->intern_res_poll_count, UG3105_MOV_AVG_WINDOW); |
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for (i = 0; i < win_size; i++) |
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chip->intern_res_avg += chip->intern_res[i]; |
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chip->intern_res_avg /= win_size; |
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out: |
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mutex_unlock(&chip->lock); |
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queue_delayed_work(system_wq, &chip->work, |
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(chip->poll_count <= UG3105_INIT_POLL_COUNT) ? |
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UG3105_INIT_POLL_TIME : UG3105_POLL_TIME); |
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if (chip->status != prev_status && psy) |
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power_supply_changed(psy); |
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} |
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static enum power_supply_property ug3105_battery_props[] = { |
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POWER_SUPPLY_PROP_STATUS, |
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POWER_SUPPLY_PROP_PRESENT, |
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POWER_SUPPLY_PROP_TECHNOLOGY, |
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POWER_SUPPLY_PROP_SCOPE, |
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POWER_SUPPLY_PROP_VOLTAGE_NOW, |
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POWER_SUPPLY_PROP_VOLTAGE_OCV, |
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POWER_SUPPLY_PROP_CURRENT_NOW, |
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POWER_SUPPLY_PROP_CAPACITY, |
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}; |
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static int ug3105_get_property(struct power_supply *psy, |
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enum power_supply_property psp, |
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union power_supply_propval *val) |
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{ |
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struct ug3105_chip *chip = power_supply_get_drvdata(psy); |
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int ret = 0; |
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mutex_lock(&chip->lock); |
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if (!chip->psy) { |
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ret = -EAGAIN; |
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goto out; |
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} |
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switch (psp) { |
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case POWER_SUPPLY_PROP_STATUS: |
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val->intval = chip->status; |
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break; |
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case POWER_SUPPLY_PROP_PRESENT: |
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val->intval = 1; |
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break; |
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case POWER_SUPPLY_PROP_TECHNOLOGY: |
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val->intval = chip->info->technology; |
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break; |
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case POWER_SUPPLY_PROP_SCOPE: |
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val->intval = POWER_SUPPLY_SCOPE_SYSTEM; |
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break; |
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case POWER_SUPPLY_PROP_VOLTAGE_NOW: |
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ret = ug3105_read_word(chip->client, UG3105_REG_BAT_VOLT); |
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if (ret < 0) |
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break; |
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val->intval = ret * chip->uv_per_unit; |
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ret = 0; |
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break; |
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case POWER_SUPPLY_PROP_VOLTAGE_OCV: |
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val->intval = chip->ocv_avg; |
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break; |
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case POWER_SUPPLY_PROP_CURRENT_NOW: |
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ret = ug3105_read_word(chip->client, UG3105_REG_BAT_CURR); |
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if (ret < 0) |
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break; |
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val->intval = (s16)ret * chip->ua_per_unit; |
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ret = 0; |
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break; |
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case POWER_SUPPLY_PROP_CAPACITY: |
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val->intval = chip->capacity; |
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break; |
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default: |
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ret = -EINVAL; |
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} |
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out: |
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mutex_unlock(&chip->lock); |
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return ret; |
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} |
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static void ug3105_external_power_changed(struct power_supply *psy) |
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{ |
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struct ug3105_chip *chip = power_supply_get_drvdata(psy); |
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dev_dbg(&chip->client->dev, "external power changed\n"); |
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mod_delayed_work(system_wq, &chip->work, UG3105_SETTLE_TIME); |
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} |
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static const struct power_supply_desc ug3105_psy_desc = { |
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.name = "ug3105_battery", |
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.type = POWER_SUPPLY_TYPE_BATTERY, |
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.get_property = ug3105_get_property, |
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.external_power_changed = ug3105_external_power_changed, |
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.properties = ug3105_battery_props, |
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.num_properties = ARRAY_SIZE(ug3105_battery_props), |
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}; |
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static void ug3105_init(struct ug3105_chip *chip) |
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{ |
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chip->poll_count = 0; |
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chip->ocv_avg_index = 0; |
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chip->total_coulomb_count = 0; |
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i2c_smbus_write_byte_data(chip->client, UG3105_REG_MODE, |
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UG3105_MODE_RUN); |
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i2c_smbus_write_byte_data(chip->client, UG3105_REG_CTRL1, |
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UG3105_CTRL1_RESET_COULOMB_CNT); |
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queue_delayed_work(system_wq, &chip->work, 0); |
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flush_delayed_work(&chip->work); |
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} |
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static int ug3105_probe(struct i2c_client *client) |
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{ |
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struct power_supply_config psy_cfg = {}; |
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struct device *dev = &client->dev; |
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u32 curr_sense_res_uohm = 10000; |
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struct power_supply *psy; |
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struct ug3105_chip *chip; |
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int ret; |
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chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL); |
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if (!chip) |
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return -ENOMEM; |
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chip->client = client; |
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mutex_init(&chip->lock); |
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ret = devm_delayed_work_autocancel(dev, &chip->work, ug3105_work); |
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if (ret) |
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return ret; |
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psy_cfg.drv_data = chip; |
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psy = devm_power_supply_register(dev, &ug3105_psy_desc, &psy_cfg); |
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if (IS_ERR(psy)) |
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return PTR_ERR(psy); |
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ret = power_supply_get_battery_info(psy, &chip->info); |
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if (ret) |
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return ret; |
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if (chip->info->factory_internal_resistance_uohm == -EINVAL || |
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chip->info->constant_charge_voltage_max_uv == -EINVAL) { |
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dev_err(dev, "error required properties are missing\n"); |
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return -ENODEV; |
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} |
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device_property_read_u32(dev, "upisemi,rsns-microohm", &curr_sense_res_uohm); |
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/* |
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* DAC maximum is 4.5V divided by 65536 steps + an unknown factor of 10 |
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* coming from somewhere for some reason (verified with a volt-meter). |
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*/ |
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chip->uv_per_unit = 45000000/65536; |
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/* Datasheet says 8.1 uV per unit for the current ADC */ |
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chip->ua_per_unit = 8100000 / curr_sense_res_uohm; |
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/* Use provided internal resistance as start point (in milli-ohm) */ |
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chip->intern_res_avg = chip->info->factory_internal_resistance_uohm / 1000; |
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/* Also add it to the internal resistance moving average window */ |
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chip->intern_res[0] = chip->intern_res_avg; |
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chip->intern_res_avg_index = 1; |
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chip->intern_res_poll_count = 1; |
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mutex_lock(&chip->lock); |
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chip->psy = psy; |
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mutex_unlock(&chip->lock); |
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ug3105_init(chip); |
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i2c_set_clientdata(client, chip); |
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return 0; |
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} |
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static int __maybe_unused ug3105_suspend(struct device *dev) |
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{ |
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struct ug3105_chip *chip = dev_get_drvdata(dev); |
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cancel_delayed_work_sync(&chip->work); |
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i2c_smbus_write_byte_data(chip->client, UG3105_REG_MODE, |
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UG3105_MODE_STANDBY); |
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return 0; |
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} |
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static int __maybe_unused ug3105_resume(struct device *dev) |
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{ |
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struct ug3105_chip *chip = dev_get_drvdata(dev); |
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ug3105_init(chip); |
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return 0; |
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} |
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static SIMPLE_DEV_PM_OPS(ug3105_pm_ops, ug3105_suspend, |
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ug3105_resume); |
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static const struct i2c_device_id ug3105_id[] = { |
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{ "ug3105" }, |
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{ } |
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}; |
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MODULE_DEVICE_TABLE(i2c, ug3105_id); |
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static struct i2c_driver ug3105_i2c_driver = { |
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.driver = { |
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.name = "ug3105", |
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.pm = &ug3105_pm_ops, |
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}, |
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.probe_new = ug3105_probe, |
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.id_table = ug3105_id, |
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}; |
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module_i2c_driver(ug3105_i2c_driver); |
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MODULE_AUTHOR("Hans de Goede <[email protected]"); |
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MODULE_DESCRIPTION("uPI uG3105 battery monitor driver"); |
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MODULE_LICENSE("GPL");
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