2 * ntc_thermistor.c - NTC Thermistors
4 * Copyright (C) 2010 Samsung Electronics
5 * MyungJoo Ham <myungjoo.ham@samsung.com>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 #include <linux/slab.h>
24 #include <linux/module.h>
25 #include <linux/pm_runtime.h>
26 #include <linux/math64.h>
27 #include <linux/platform_device.h>
28 #include <linux/err.h>
30 #include <linux/platform_data/ntc_thermistor.h>
32 #include <linux/hwmon.h>
33 #include <linux/hwmon-sysfs.h>
35 struct ntc_compensation
{
41 * A compensation table should be sorted by the values of .ohm
42 * in descending order.
43 * The following compensation tables are from the specification of Murata NTC
44 * Thermistors Datasheet
46 const struct ntc_compensation ncpXXwb473
[] = {
47 { .temp_C
= -40, .ohm
= 1747920 },
48 { .temp_C
= -35, .ohm
= 1245428 },
49 { .temp_C
= -30, .ohm
= 898485 },
50 { .temp_C
= -25, .ohm
= 655802 },
51 { .temp_C
= -20, .ohm
= 483954 },
52 { .temp_C
= -15, .ohm
= 360850 },
53 { .temp_C
= -10, .ohm
= 271697 },
54 { .temp_C
= -5, .ohm
= 206463 },
55 { .temp_C
= 0, .ohm
= 158214 },
56 { .temp_C
= 5, .ohm
= 122259 },
57 { .temp_C
= 10, .ohm
= 95227 },
58 { .temp_C
= 15, .ohm
= 74730 },
59 { .temp_C
= 20, .ohm
= 59065 },
60 { .temp_C
= 25, .ohm
= 47000 },
61 { .temp_C
= 30, .ohm
= 37643 },
62 { .temp_C
= 35, .ohm
= 30334 },
63 { .temp_C
= 40, .ohm
= 24591 },
64 { .temp_C
= 45, .ohm
= 20048 },
65 { .temp_C
= 50, .ohm
= 16433 },
66 { .temp_C
= 55, .ohm
= 13539 },
67 { .temp_C
= 60, .ohm
= 11209 },
68 { .temp_C
= 65, .ohm
= 9328 },
69 { .temp_C
= 70, .ohm
= 7798 },
70 { .temp_C
= 75, .ohm
= 6544 },
71 { .temp_C
= 80, .ohm
= 5518 },
72 { .temp_C
= 85, .ohm
= 4674 },
73 { .temp_C
= 90, .ohm
= 3972 },
74 { .temp_C
= 95, .ohm
= 3388 },
75 { .temp_C
= 100, .ohm
= 2902 },
76 { .temp_C
= 105, .ohm
= 2494 },
77 { .temp_C
= 110, .ohm
= 2150 },
78 { .temp_C
= 115, .ohm
= 1860 },
79 { .temp_C
= 120, .ohm
= 1615 },
80 { .temp_C
= 125, .ohm
= 1406 },
82 const struct ntc_compensation ncpXXwl333
[] = {
83 { .temp_C
= -40, .ohm
= 1610154 },
84 { .temp_C
= -35, .ohm
= 1130850 },
85 { .temp_C
= -30, .ohm
= 802609 },
86 { .temp_C
= -25, .ohm
= 575385 },
87 { .temp_C
= -20, .ohm
= 416464 },
88 { .temp_C
= -15, .ohm
= 304219 },
89 { .temp_C
= -10, .ohm
= 224193 },
90 { .temp_C
= -5, .ohm
= 166623 },
91 { .temp_C
= 0, .ohm
= 124850 },
92 { .temp_C
= 5, .ohm
= 94287 },
93 { .temp_C
= 10, .ohm
= 71747 },
94 { .temp_C
= 15, .ohm
= 54996 },
95 { .temp_C
= 20, .ohm
= 42455 },
96 { .temp_C
= 25, .ohm
= 33000 },
97 { .temp_C
= 30, .ohm
= 25822 },
98 { .temp_C
= 35, .ohm
= 20335 },
99 { .temp_C
= 40, .ohm
= 16115 },
100 { .temp_C
= 45, .ohm
= 12849 },
101 { .temp_C
= 50, .ohm
= 10306 },
102 { .temp_C
= 55, .ohm
= 8314 },
103 { .temp_C
= 60, .ohm
= 6746 },
104 { .temp_C
= 65, .ohm
= 5503 },
105 { .temp_C
= 70, .ohm
= 4513 },
106 { .temp_C
= 75, .ohm
= 3721 },
107 { .temp_C
= 80, .ohm
= 3084 },
108 { .temp_C
= 85, .ohm
= 2569 },
109 { .temp_C
= 90, .ohm
= 2151 },
110 { .temp_C
= 95, .ohm
= 1809 },
111 { .temp_C
= 100, .ohm
= 1529 },
112 { .temp_C
= 105, .ohm
= 1299 },
113 { .temp_C
= 110, .ohm
= 1108 },
114 { .temp_C
= 115, .ohm
= 949 },
115 { .temp_C
= 120, .ohm
= 817 },
116 { .temp_C
= 125, .ohm
= 707 },
120 struct device
*hwmon_dev
;
121 struct ntc_thermistor_platform_data
*pdata
;
122 const struct ntc_compensation
*comp
;
125 char name
[PLATFORM_NAME_SIZE
];
128 static inline u64
div64_u64_safe(u64 dividend
, u64 divisor
)
130 if (divisor
== 0 && dividend
== 0)
134 return div64_u64(dividend
, divisor
);
137 static unsigned int get_ohm_of_thermistor(struct ntc_data
*data
,
140 struct ntc_thermistor_platform_data
*pdata
= data
->pdata
;
142 u64 pmV
= pdata
->pullup_uV
/ 1000;
144 puO
= pdata
->pullup_ohm
;
145 pdO
= pdata
->pulldown_ohm
;
148 if (pdata
->connect
== NTC_CONNECTED_POSITIVE
)
153 return (pdata
->connect
== NTC_CONNECTED_POSITIVE
) ?
156 if (pdata
->connect
== NTC_CONNECTED_POSITIVE
&& puO
== 0)
157 N
= div64_u64_safe(pdO
* (pmV
- mV
), mV
);
158 else if (pdata
->connect
== NTC_CONNECTED_GROUND
&& pdO
== 0)
159 N
= div64_u64_safe(puO
* mV
, pmV
- mV
);
160 else if (pdata
->connect
== NTC_CONNECTED_POSITIVE
)
161 N
= div64_u64_safe(pdO
* puO
* (pmV
- mV
),
162 puO
* mV
- pdO
* (pmV
- mV
));
164 N
= div64_u64_safe(pdO
* puO
* mV
, pdO
* (pmV
- mV
) - puO
* mV
);
166 return (unsigned int) N
;
169 static int lookup_comp(struct ntc_data
*data
,
170 unsigned int ohm
, int *i_low
, int *i_high
)
172 int start
, end
, mid
= -1;
174 /* Do a binary search on compensation table */
178 while (end
> start
) {
179 mid
= start
+ (end
- start
) / 2;
180 if (data
->comp
[mid
].ohm
< ohm
)
182 else if (data
->comp
[mid
].ohm
> ohm
)
189 if (data
->comp
[mid
].ohm
> ohm
) {
199 if (mid
== (data
->n_comp
- 1)) {
200 if (data
->comp
[mid
].ohm
<= ohm
) {
211 if (data
->comp
[mid
].ohm
<= ohm
) {
215 if (data
->comp
[mid
].ohm
> ohm
) {
223 static int get_temp_mC(struct ntc_data
*data
, unsigned int ohm
, int *temp
)
228 ret
= lookup_comp(data
, ohm
, &low
, &high
);
230 /* Unable to use linear approximation */
232 *temp
= data
->comp
[low
].temp_C
* 1000;
234 *temp
= data
->comp
[high
].temp_C
* 1000;
238 *temp
= data
->comp
[low
].temp_C
* 1000 +
239 ((data
->comp
[high
].temp_C
- data
->comp
[low
].temp_C
) *
240 1000 * ((int)ohm
- (int)data
->comp
[low
].ohm
)) /
241 ((int)data
->comp
[high
].ohm
- (int)data
->comp
[low
].ohm
);
247 static int ntc_thermistor_read(struct ntc_data
*data
, int *temp
)
250 int read_ohm
, read_uV
;
251 unsigned int ohm
= 0;
253 if (data
->pdata
->read_ohm
) {
254 read_ohm
= data
->pdata
->read_ohm();
257 ohm
= (unsigned int)read_ohm
;
260 if (data
->pdata
->read_uV
) {
261 read_uV
= data
->pdata
->read_uV();
264 ohm
= get_ohm_of_thermistor(data
, (unsigned int)read_uV
);
267 ret
= get_temp_mC(data
, ohm
, temp
);
269 dev_dbg(data
->dev
, "Sensor reading function not available.\n");
276 static ssize_t
ntc_show_name(struct device
*dev
,
277 struct device_attribute
*attr
, char *buf
)
279 struct ntc_data
*data
= dev_get_drvdata(dev
);
281 return sprintf(buf
, "%s\n", data
->name
);
284 static ssize_t
ntc_show_type(struct device
*dev
,
285 struct device_attribute
*attr
, char *buf
)
287 return sprintf(buf
, "4\n");
290 static ssize_t
ntc_show_temp(struct device
*dev
,
291 struct device_attribute
*attr
, char *buf
)
293 struct ntc_data
*data
= dev_get_drvdata(dev
);
296 ret
= ntc_thermistor_read(data
, &temp
);
299 return sprintf(buf
, "%d\n", temp
);
302 static SENSOR_DEVICE_ATTR(temp1_type
, S_IRUGO
, ntc_show_type
, NULL
, 0);
303 static SENSOR_DEVICE_ATTR(temp1_input
, S_IRUGO
, ntc_show_temp
, NULL
, 0);
304 static DEVICE_ATTR(name
, S_IRUGO
, ntc_show_name
, NULL
);
306 static struct attribute
*ntc_attributes
[] = {
308 &sensor_dev_attr_temp1_type
.dev_attr
.attr
,
309 &sensor_dev_attr_temp1_input
.dev_attr
.attr
,
313 static const struct attribute_group ntc_attr_group
= {
314 .attrs
= ntc_attributes
,
317 static int __devinit
ntc_thermistor_probe(struct platform_device
*pdev
)
319 struct ntc_data
*data
;
320 struct ntc_thermistor_platform_data
*pdata
= pdev
->dev
.platform_data
;
324 dev_err(&pdev
->dev
, "No platform init data supplied.\n");
328 /* Either one of the two is required. */
329 if (!pdata
->read_uV
&& !pdata
->read_ohm
) {
330 dev_err(&pdev
->dev
, "Both read_uV and read_ohm missing."
331 "Need either one of the two.\n");
335 if (pdata
->read_uV
&& pdata
->read_ohm
) {
336 dev_warn(&pdev
->dev
, "Only one of read_uV and read_ohm "
337 "is needed; ignoring read_uV.\n");
338 pdata
->read_uV
= NULL
;
341 if (pdata
->read_uV
&& (pdata
->pullup_uV
== 0 ||
342 (pdata
->pullup_ohm
== 0 && pdata
->connect
==
343 NTC_CONNECTED_GROUND
) ||
344 (pdata
->pulldown_ohm
== 0 && pdata
->connect
==
345 NTC_CONNECTED_POSITIVE
) ||
346 (pdata
->connect
!= NTC_CONNECTED_POSITIVE
&&
347 pdata
->connect
!= NTC_CONNECTED_GROUND
))) {
348 dev_err(&pdev
->dev
, "Required data to use read_uV not "
353 data
= kzalloc(sizeof(struct ntc_data
), GFP_KERNEL
);
357 data
->dev
= &pdev
->dev
;
359 strncpy(data
->name
, pdev
->id_entry
->name
, PLATFORM_NAME_SIZE
);
361 switch (pdev
->id_entry
->driver_data
) {
362 case TYPE_NCPXXWB473
:
363 data
->comp
= ncpXXwb473
;
364 data
->n_comp
= ARRAY_SIZE(ncpXXwb473
);
366 case TYPE_NCPXXWL333
:
367 data
->comp
= ncpXXwl333
;
368 data
->n_comp
= ARRAY_SIZE(ncpXXwl333
);
371 dev_err(&pdev
->dev
, "Unknown device type: %lu(%s)\n",
372 pdev
->id_entry
->driver_data
,
373 pdev
->id_entry
->name
);
378 platform_set_drvdata(pdev
, data
);
380 ret
= sysfs_create_group(&data
->dev
->kobj
, &ntc_attr_group
);
382 dev_err(data
->dev
, "unable to create sysfs files\n");
386 data
->hwmon_dev
= hwmon_device_register(data
->dev
);
387 if (IS_ERR_OR_NULL(data
->hwmon_dev
)) {
388 dev_err(data
->dev
, "unable to register as hwmon device.\n");
390 goto err_after_sysfs
;
393 dev_info(&pdev
->dev
, "Thermistor %s:%d (type: %s/%lu) successfully probed.\n",
394 pdev
->name
, pdev
->id
, pdev
->id_entry
->name
,
395 pdev
->id_entry
->driver_data
);
398 sysfs_remove_group(&data
->dev
->kobj
, &ntc_attr_group
);
404 static int __devexit
ntc_thermistor_remove(struct platform_device
*pdev
)
406 struct ntc_data
*data
= platform_get_drvdata(pdev
);
408 hwmon_device_unregister(data
->hwmon_dev
);
409 sysfs_remove_group(&data
->dev
->kobj
, &ntc_attr_group
);
410 platform_set_drvdata(pdev
, NULL
);
417 static const struct platform_device_id ntc_thermistor_id
[] = {
418 { "ncp15wb473", TYPE_NCPXXWB473
},
419 { "ncp18wb473", TYPE_NCPXXWB473
},
420 { "ncp21wb473", TYPE_NCPXXWB473
},
421 { "ncp03wb473", TYPE_NCPXXWB473
},
422 { "ncp15wl333", TYPE_NCPXXWL333
},
426 static struct platform_driver ntc_thermistor_driver
= {
428 .name
= "ntc-thermistor",
429 .owner
= THIS_MODULE
,
431 .probe
= ntc_thermistor_probe
,
432 .remove
= __devexit_p(ntc_thermistor_remove
),
433 .id_table
= ntc_thermistor_id
,
436 static int __init
ntc_thermistor_init(void)
438 return platform_driver_register(&ntc_thermistor_driver
);
441 module_init(ntc_thermistor_init
);
443 static void __exit
ntc_thermistor_cleanup(void)
445 platform_driver_unregister(&ntc_thermistor_driver
);
448 module_exit(ntc_thermistor_cleanup
);
450 MODULE_DESCRIPTION("NTC Thermistor Driver");
451 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
452 MODULE_LICENSE("GPL");
453 MODULE_ALIAS("platform:ntc-thermistor");