/* * ntc_thermistor.c - NTC Thermistors * * Copyright (C) 2010 Samsung Electronics * MyungJoo Ham * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * */ #include #include #include #include #include #include #include #include #include struct ntc_compensation { int temp_C; unsigned int ohm; }; /* * A compensation table should be sorted by the values of .ohm * in descending order. * The following compensation tables are from the specification of Murata NTC * Thermistors Datasheet */ const struct ntc_compensation ncpXXwb473[] = { { .temp_C = -40, .ohm = 1747920 }, { .temp_C = -35, .ohm = 1245428 }, { .temp_C = -30, .ohm = 898485 }, { .temp_C = -25, .ohm = 655802 }, { .temp_C = -20, .ohm = 483954 }, { .temp_C = -15, .ohm = 360850 }, { .temp_C = -10, .ohm = 271697 }, { .temp_C = -5, .ohm = 206463 }, { .temp_C = 0, .ohm = 158214 }, { .temp_C = 5, .ohm = 122259 }, { .temp_C = 10, .ohm = 95227 }, { .temp_C = 15, .ohm = 74730 }, { .temp_C = 20, .ohm = 59065 }, { .temp_C = 25, .ohm = 47000 }, { .temp_C = 30, .ohm = 37643 }, { .temp_C = 35, .ohm = 30334 }, { .temp_C = 40, .ohm = 24591 }, { .temp_C = 45, .ohm = 20048 }, { .temp_C = 50, .ohm = 16433 }, { .temp_C = 55, .ohm = 13539 }, { .temp_C = 60, .ohm = 11209 }, { .temp_C = 65, .ohm = 9328 }, { .temp_C = 70, .ohm = 7798 }, { .temp_C = 75, .ohm = 6544 }, { .temp_C = 80, .ohm = 5518 }, { .temp_C = 85, .ohm = 4674 }, { .temp_C = 90, .ohm = 3972 }, { .temp_C = 95, .ohm = 3388 }, { .temp_C = 100, .ohm = 2902 }, { .temp_C = 105, .ohm = 2494 }, { .temp_C = 110, .ohm = 2150 }, { .temp_C = 115, .ohm = 1860 }, { .temp_C = 120, .ohm = 1615 }, { .temp_C = 125, .ohm = 1406 }, }; const struct ntc_compensation ncpXXwl333[] = { { .temp_C = -40, .ohm = 1610154 }, { .temp_C = -35, .ohm = 1130850 }, { .temp_C = -30, .ohm = 802609 }, { .temp_C = -25, .ohm = 575385 }, { .temp_C = -20, .ohm = 416464 }, { .temp_C = -15, .ohm = 304219 }, { .temp_C = -10, .ohm = 224193 }, { .temp_C = -5, .ohm = 166623 }, { .temp_C = 0, .ohm = 124850 }, { .temp_C = 5, .ohm = 94287 }, { .temp_C = 10, .ohm = 71747 }, { .temp_C = 15, .ohm = 54996 }, { .temp_C = 20, .ohm = 42455 }, { .temp_C = 25, .ohm = 33000 }, { .temp_C = 30, .ohm = 25822 }, { .temp_C = 35, .ohm = 20335 }, { .temp_C = 40, .ohm = 16115 }, { .temp_C = 45, .ohm = 12849 }, { .temp_C = 50, .ohm = 10306 }, { .temp_C = 55, .ohm = 8314 }, { .temp_C = 60, .ohm = 6746 }, { .temp_C = 65, .ohm = 5503 }, { .temp_C = 70, .ohm = 4513 }, { .temp_C = 75, .ohm = 3721 }, { .temp_C = 80, .ohm = 3084 }, { .temp_C = 85, .ohm = 2569 }, { .temp_C = 90, .ohm = 2151 }, { .temp_C = 95, .ohm = 1809 }, { .temp_C = 100, .ohm = 1529 }, { .temp_C = 105, .ohm = 1299 }, { .temp_C = 110, .ohm = 1108 }, { .temp_C = 115, .ohm = 949 }, { .temp_C = 120, .ohm = 817 }, { .temp_C = 125, .ohm = 707 }, }; struct ntc_data { struct device *hwmon_dev; struct ntc_thermistor_platform_data *pdata; const struct ntc_compensation *comp; struct device *dev; int n_comp; char name[PLATFORM_NAME_SIZE]; }; static inline u64 div64_u64_safe(u64 dividend, u64 divisor) { if (divisor == 0 && dividend == 0) return 0; if (divisor == 0) return UINT_MAX; return div64_u64(dividend, divisor); } static int get_ohm_of_thermistor(struct ntc_data *data, unsigned int uV) { struct ntc_thermistor_platform_data *pdata = data->pdata; u64 mV = uV / 1000; u64 pmV = pdata->pullup_uV / 1000; u64 N, puO, pdO; puO = pdata->pullup_ohm; pdO = pdata->pulldown_ohm; if (mV == 0) { if (pdata->connect == NTC_CONNECTED_POSITIVE) return INT_MAX; return 0; } if (mV >= pmV) return (pdata->connect == NTC_CONNECTED_POSITIVE) ? 0 : INT_MAX; if (pdata->connect == NTC_CONNECTED_POSITIVE && puO == 0) N = div64_u64_safe(pdO * (pmV - mV), mV); else if (pdata->connect == NTC_CONNECTED_GROUND && pdO == 0) N = div64_u64_safe(puO * mV, pmV - mV); else if (pdata->connect == NTC_CONNECTED_POSITIVE) N = div64_u64_safe(pdO * puO * (pmV - mV), puO * mV - pdO * (pmV - mV)); else N = div64_u64_safe(pdO * puO * mV, pdO * (pmV - mV) - puO * mV); if (N > INT_MAX) N = INT_MAX; return N; } static void lookup_comp(struct ntc_data *data, unsigned int ohm, int *i_low, int *i_high) { int start, end, mid; /* * Handle special cases: Resistance is higher than or equal to * resistance in first table entry, or resistance is lower or equal * to resistance in last table entry. * In these cases, return i_low == i_high, either pointing to the * beginning or to the end of the table depending on the condition. */ if (ohm >= data->comp[0].ohm) { *i_low = 0; *i_high = 0; return; } if (ohm <= data->comp[data->n_comp - 1].ohm) { *i_low = data->n_comp - 1; *i_high = data->n_comp - 1; return; } /* Do a binary search on compensation table */ start = 0; end = data->n_comp; while (start < end) { mid = start + (end - start) / 2; /* * start <= mid < end * data->comp[start].ohm > ohm >= data->comp[end].ohm * * We could check for "ohm == data->comp[mid].ohm" here, but * that is a quite unlikely condition, and we would have to * check again after updating start. Check it at the end instead * for simplicity. */ if (ohm >= data->comp[mid].ohm) { end = mid; } else { start = mid + 1; /* * ohm >= data->comp[start].ohm might be true here, * since we set start to mid + 1. In that case, we are * done. We could keep going, but the condition is quite * likely to occur, so it is worth checking for it. */ if (ohm >= data->comp[start].ohm) end = start; } /* * start <= end * data->comp[start].ohm >= ohm >= data->comp[end].ohm */ } /* * start == end * ohm >= data->comp[end].ohm */ *i_low = end; if (ohm == data->comp[end].ohm) *i_high = end; else *i_high = end - 1; } static int get_temp_mC(struct ntc_data *data, unsigned int ohm) { int low, high; int temp; lookup_comp(data, ohm, &low, &high); if (low == high) { /* Unable to use linear approximation */ temp = data->comp[low].temp_C * 1000; } else { temp = data->comp[low].temp_C * 1000 + ((data->comp[high].temp_C - data->comp[low].temp_C) * 1000 * ((int)ohm - (int)data->comp[low].ohm)) / ((int)data->comp[high].ohm - (int)data->comp[low].ohm); } return temp; } static int ntc_thermistor_get_ohm(struct ntc_data *data) { int read_uV; if (data->pdata->read_ohm) return data->pdata->read_ohm(); if (data->pdata->read_uV) { read_uV = data->pdata->read_uV(); if (read_uV < 0) return read_uV; return get_ohm_of_thermistor(data, read_uV); } return -EINVAL; } static ssize_t ntc_show_name(struct device *dev, struct device_attribute *attr, char *buf) { struct ntc_data *data = dev_get_drvdata(dev); return sprintf(buf, "%s\n", data->name); } static ssize_t ntc_show_type(struct device *dev, struct device_attribute *attr, char *buf) { return sprintf(buf, "4\n"); } static ssize_t ntc_show_temp(struct device *dev, struct device_attribute *attr, char *buf) { struct ntc_data *data = dev_get_drvdata(dev); int ohm; ohm = ntc_thermistor_get_ohm(data); if (ohm < 0) return ohm; return sprintf(buf, "%d\n", get_temp_mC(data, ohm)); } static SENSOR_DEVICE_ATTR(temp1_type, S_IRUGO, ntc_show_type, NULL, 0); static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ntc_show_temp, NULL, 0); static DEVICE_ATTR(name, S_IRUGO, ntc_show_name, NULL); static struct attribute *ntc_attributes[] = { &dev_attr_name.attr, &sensor_dev_attr_temp1_type.dev_attr.attr, &sensor_dev_attr_temp1_input.dev_attr.attr, NULL, }; static const struct attribute_group ntc_attr_group = { .attrs = ntc_attributes, }; static int __devinit ntc_thermistor_probe(struct platform_device *pdev) { struct ntc_data *data; struct ntc_thermistor_platform_data *pdata = pdev->dev.platform_data; int ret = 0; if (!pdata) { dev_err(&pdev->dev, "No platform init data supplied.\n"); return -ENODEV; } /* Either one of the two is required. */ if (!pdata->read_uV && !pdata->read_ohm) { dev_err(&pdev->dev, "Both read_uV and read_ohm missing. Need either one of the two.\n"); return -EINVAL; } if (pdata->read_uV && pdata->read_ohm) { dev_warn(&pdev->dev, "Only one of read_uV and read_ohm is needed; ignoring read_uV.\n"); pdata->read_uV = NULL; } if (pdata->read_uV && (pdata->pullup_uV == 0 || (pdata->pullup_ohm == 0 && pdata->connect == NTC_CONNECTED_GROUND) || (pdata->pulldown_ohm == 0 && pdata->connect == NTC_CONNECTED_POSITIVE) || (pdata->connect != NTC_CONNECTED_POSITIVE && pdata->connect != NTC_CONNECTED_GROUND))) { dev_err(&pdev->dev, "Required data to use read_uV not supplied.\n"); return -EINVAL; } data = devm_kzalloc(&pdev->dev, sizeof(struct ntc_data), GFP_KERNEL); if (!data) return -ENOMEM; data->dev = &pdev->dev; data->pdata = pdata; strlcpy(data->name, pdev->id_entry->name, sizeof(data->name)); switch (pdev->id_entry->driver_data) { case TYPE_NCPXXWB473: data->comp = ncpXXwb473; data->n_comp = ARRAY_SIZE(ncpXXwb473); break; case TYPE_NCPXXWL333: data->comp = ncpXXwl333; data->n_comp = ARRAY_SIZE(ncpXXwl333); break; default: dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n", pdev->id_entry->driver_data, pdev->id_entry->name); return -EINVAL; } platform_set_drvdata(pdev, data); ret = sysfs_create_group(&data->dev->kobj, &ntc_attr_group); if (ret) { dev_err(data->dev, "unable to create sysfs files\n"); return ret; } data->hwmon_dev = hwmon_device_register(data->dev); if (IS_ERR(data->hwmon_dev)) { dev_err(data->dev, "unable to register as hwmon device.\n"); ret = PTR_ERR(data->hwmon_dev); goto err_after_sysfs; } dev_info(&pdev->dev, "Thermistor %s:%d (type: %s/%lu) successfully probed.\n", pdev->name, pdev->id, pdev->id_entry->name, pdev->id_entry->driver_data); return 0; err_after_sysfs: sysfs_remove_group(&data->dev->kobj, &ntc_attr_group); return ret; } static int __devexit ntc_thermistor_remove(struct platform_device *pdev) { struct ntc_data *data = platform_get_drvdata(pdev); hwmon_device_unregister(data->hwmon_dev); sysfs_remove_group(&data->dev->kobj, &ntc_attr_group); platform_set_drvdata(pdev, NULL); return 0; } static const struct platform_device_id ntc_thermistor_id[] = { { "ncp15wb473", TYPE_NCPXXWB473 }, { "ncp18wb473", TYPE_NCPXXWB473 }, { "ncp21wb473", TYPE_NCPXXWB473 }, { "ncp03wb473", TYPE_NCPXXWB473 }, { "ncp15wl333", TYPE_NCPXXWL333 }, { }, }; static struct platform_driver ntc_thermistor_driver = { .driver = { .name = "ntc-thermistor", .owner = THIS_MODULE, }, .probe = ntc_thermistor_probe, .remove = __devexit_p(ntc_thermistor_remove), .id_table = ntc_thermistor_id, }; module_platform_driver(ntc_thermistor_driver); MODULE_DESCRIPTION("NTC Thermistor Driver"); MODULE_AUTHOR("MyungJoo Ham "); MODULE_LICENSE("GPL"); MODULE_ALIAS("platform:ntc-thermistor");