1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * lm77.c - Part of lm_sensors, Linux kernel modules for hardware
4 *	    monitoring
5 *
6 * Copyright (c) 2004  Andras BALI <drewie@freemail.hu>
7 *
8 * Heavily based on lm75.c by Frodo Looijaard <frodol@dds.nl>.  The LM77
9 * is a temperature sensor and thermal window comparator with 0.5 deg
10 * resolution made by National Semiconductor.  Complete datasheet can be
11 * obtained at their site:
12 *	http://www.national.com/pf/LM/LM77.html
13 */
14
15#include <linux/module.h>
16#include <linux/init.h>
17#include <linux/slab.h>
18#include <linux/jiffies.h>
19#include <linux/i2c.h>
20#include <linux/hwmon.h>
21#include <linux/hwmon-sysfs.h>
22#include <linux/err.h>
23#include <linux/mutex.h>
24
25/* Addresses to scan */
26static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
27						I2C_CLIENT_END };
28
29/* The LM77 registers */
30#define LM77_REG_TEMP		0x00
31#define LM77_REG_CONF		0x01
32#define LM77_REG_TEMP_HYST	0x02
33#define LM77_REG_TEMP_CRIT	0x03
34#define LM77_REG_TEMP_MIN	0x04
35#define LM77_REG_TEMP_MAX	0x05
36
37enum temp_index {
38	t_input = 0,
39	t_crit,
40	t_min,
41	t_max,
42	t_hyst,
43	t_num_temp
44};
45
46static const u8 temp_regs[t_num_temp] = {
47	[t_input] = LM77_REG_TEMP,
48	[t_min] = LM77_REG_TEMP_MIN,
49	[t_max] = LM77_REG_TEMP_MAX,
50	[t_crit] = LM77_REG_TEMP_CRIT,
51	[t_hyst] = LM77_REG_TEMP_HYST,
52};
53
54/* Each client has this additional data */
55struct lm77_data {
56	struct i2c_client	*client;
57	struct mutex		update_lock;
58	bool			valid;
59	unsigned long		last_updated;	/* In jiffies */
60	int			temp[t_num_temp]; /* index using temp_index */
61	u8			alarms;
62};
63
64/* straight from the datasheet */
65#define LM77_TEMP_MIN (-55000)
66#define LM77_TEMP_MAX 125000
67
68/*
69 * In the temperature registers, the low 3 bits are not part of the
70 * temperature values; they are the status bits.
71 */
72static inline s16 LM77_TEMP_TO_REG(int temp)
73{
74	return (temp / 500) * 8;
75}
76
77static inline int LM77_TEMP_FROM_REG(s16 reg)
78{
79	return (reg / 8) * 500;
80}
81
82/*
83 * All registers are word-sized, except for the configuration register.
84 * The LM77 uses the high-byte first convention.
85 */
86static u16 lm77_read_value(struct i2c_client *client, u8 reg)
87{
88	if (reg == LM77_REG_CONF)
89		return i2c_smbus_read_byte_data(client, reg);
90	else
91		return i2c_smbus_read_word_swapped(client, reg);
92}
93
94static int lm77_write_value(struct i2c_client *client, u8 reg, u16 value)
95{
96	if (reg == LM77_REG_CONF)
97		return i2c_smbus_write_byte_data(client, reg, value);
98	else
99		return i2c_smbus_write_word_swapped(client, reg, value);
100}
101
102static struct lm77_data *lm77_update_device(struct device *dev)
103{
104	struct lm77_data *data = dev_get_drvdata(dev);
105	struct i2c_client *client = data->client;
106	int i;
107
108	mutex_lock(&data->update_lock);
109
110	if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
111	    || !data->valid) {
112		dev_dbg(&client->dev, "Starting lm77 update\n");
113		for (i = 0; i < t_num_temp; i++) {
114			data->temp[i] =
115			  LM77_TEMP_FROM_REG(lm77_read_value(client,
116							     temp_regs[i]));
117		}
118		data->alarms =
119			lm77_read_value(client, LM77_REG_TEMP) & 0x0007;
120		data->last_updated = jiffies;
121		data->valid = true;
122	}
123
124	mutex_unlock(&data->update_lock);
125
126	return data;
127}
128
129/* sysfs stuff */
130
131static ssize_t temp_show(struct device *dev, struct device_attribute *devattr,
132			 char *buf)
133{
134	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
135	struct lm77_data *data = lm77_update_device(dev);
136
137	return sprintf(buf, "%d\n", data->temp[attr->index]);
138}
139
140static ssize_t temp_hyst_show(struct device *dev,
141			      struct device_attribute *devattr, char *buf)
142{
143	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
144	struct lm77_data *data = lm77_update_device(dev);
145	int nr = attr->index;
146	int temp;
147
148	temp = nr == t_min ? data->temp[nr] + data->temp[t_hyst] :
149			     data->temp[nr] - data->temp[t_hyst];
150
151	return sprintf(buf, "%d\n", temp);
152}
153
154static ssize_t temp_store(struct device *dev,
155			  struct device_attribute *devattr, const char *buf,
156			  size_t count)
157{
158	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
159	struct lm77_data *data = dev_get_drvdata(dev);
160	struct i2c_client *client = data->client;
161	int nr = attr->index;
162	long val;
163	int err;
164
165	err = kstrtol(buf, 10, &val);
166	if (err)
167		return err;
168
169	val = clamp_val(val, LM77_TEMP_MIN, LM77_TEMP_MAX);
170	mutex_lock(&data->update_lock);
171	data->temp[nr] = val;
172	lm77_write_value(client, temp_regs[nr], LM77_TEMP_TO_REG(val));
173	mutex_unlock(&data->update_lock);
174	return count;
175}
176
177/*
178 * hysteresis is stored as a relative value on the chip, so it has to be
179 * converted first.
180 */
181static ssize_t temp_hyst_store(struct device *dev,
182			       struct device_attribute *devattr,
183			       const char *buf, size_t count)
184{
185	struct lm77_data *data = dev_get_drvdata(dev);
186	struct i2c_client *client = data->client;
187	long val;
188	int err;
189
190	err = kstrtol(buf, 10, &val);
191	if (err)
192		return err;
193
194	mutex_lock(&data->update_lock);
195	val = clamp_val(data->temp[t_crit] - val, LM77_TEMP_MIN, LM77_TEMP_MAX);
196	data->temp[t_hyst] = val;
197	lm77_write_value(client, LM77_REG_TEMP_HYST,
198			 LM77_TEMP_TO_REG(data->temp[t_hyst]));
199	mutex_unlock(&data->update_lock);
200	return count;
201}
202
203static ssize_t alarm_show(struct device *dev, struct device_attribute *attr,
204			  char *buf)
205{
206	int bitnr = to_sensor_dev_attr(attr)->index;
207	struct lm77_data *data = lm77_update_device(dev);
208	return sprintf(buf, "%u\n", (data->alarms >> bitnr) & 1);
209}
210
211static SENSOR_DEVICE_ATTR_RO(temp1_input, temp, t_input);
212static SENSOR_DEVICE_ATTR_RW(temp1_crit, temp, t_crit);
213static SENSOR_DEVICE_ATTR_RW(temp1_min, temp, t_min);
214static SENSOR_DEVICE_ATTR_RW(temp1_max, temp, t_max);
215
216static SENSOR_DEVICE_ATTR_RW(temp1_crit_hyst, temp_hyst, t_crit);
217static SENSOR_DEVICE_ATTR_RO(temp1_min_hyst, temp_hyst, t_min);
218static SENSOR_DEVICE_ATTR_RO(temp1_max_hyst, temp_hyst, t_max);
219
220static SENSOR_DEVICE_ATTR_RO(temp1_crit_alarm, alarm, 2);
221static SENSOR_DEVICE_ATTR_RO(temp1_min_alarm, alarm, 0);
222static SENSOR_DEVICE_ATTR_RO(temp1_max_alarm, alarm, 1);
223
224static struct attribute *lm77_attrs[] = {
225	&sensor_dev_attr_temp1_input.dev_attr.attr,
226	&sensor_dev_attr_temp1_crit.dev_attr.attr,
227	&sensor_dev_attr_temp1_min.dev_attr.attr,
228	&sensor_dev_attr_temp1_max.dev_attr.attr,
229	&sensor_dev_attr_temp1_crit_hyst.dev_attr.attr,
230	&sensor_dev_attr_temp1_min_hyst.dev_attr.attr,
231	&sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
232	&sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
233	&sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
234	&sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
235	NULL
236};
237ATTRIBUTE_GROUPS(lm77);
238
239/* Return 0 if detection is successful, -ENODEV otherwise */
240static int lm77_detect(struct i2c_client *client, struct i2c_board_info *info)
241{
242	struct i2c_adapter *adapter = client->adapter;
243	int i, cur, conf, hyst, crit, min, max;
244
245	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
246				     I2C_FUNC_SMBUS_WORD_DATA))
247		return -ENODEV;
248
249	/*
250	 * Here comes the remaining detection.  Since the LM77 has no
251	 * register dedicated to identification, we have to rely on the
252	 * following tricks:
253	 *
254	 * 1. the high 4 bits represent the sign and thus they should
255	 *    always be the same
256	 * 2. the high 3 bits are unused in the configuration register
257	 * 3. addresses 0x06 and 0x07 return the last read value
258	 * 4. registers cycling over 8-address boundaries
259	 *
260	 * Word-sized registers are high-byte first.
261	 */
262
263	/* addresses cycling */
264	cur = i2c_smbus_read_word_data(client, 0);
265	conf = i2c_smbus_read_byte_data(client, 1);
266	hyst = i2c_smbus_read_word_data(client, 2);
267	crit = i2c_smbus_read_word_data(client, 3);
268	min = i2c_smbus_read_word_data(client, 4);
269	max = i2c_smbus_read_word_data(client, 5);
270	for (i = 8; i <= 0xff; i += 8) {
271		if (i2c_smbus_read_byte_data(client, i + 1) != conf
272		 || i2c_smbus_read_word_data(client, i + 2) != hyst
273		 || i2c_smbus_read_word_data(client, i + 3) != crit
274		 || i2c_smbus_read_word_data(client, i + 4) != min
275		 || i2c_smbus_read_word_data(client, i + 5) != max)
276			return -ENODEV;
277	}
278
279	/* sign bits */
280	if (((cur & 0x00f0) != 0xf0 && (cur & 0x00f0) != 0x0)
281	 || ((hyst & 0x00f0) != 0xf0 && (hyst & 0x00f0) != 0x0)
282	 || ((crit & 0x00f0) != 0xf0 && (crit & 0x00f0) != 0x0)
283	 || ((min & 0x00f0) != 0xf0 && (min & 0x00f0) != 0x0)
284	 || ((max & 0x00f0) != 0xf0 && (max & 0x00f0) != 0x0))
285		return -ENODEV;
286
287	/* unused bits */
288	if (conf & 0xe0)
289		return -ENODEV;
290
291	/* 0x06 and 0x07 return the last read value */
292	cur = i2c_smbus_read_word_data(client, 0);
293	if (i2c_smbus_read_word_data(client, 6) != cur
294	 || i2c_smbus_read_word_data(client, 7) != cur)
295		return -ENODEV;
296	hyst = i2c_smbus_read_word_data(client, 2);
297	if (i2c_smbus_read_word_data(client, 6) != hyst
298	 || i2c_smbus_read_word_data(client, 7) != hyst)
299		return -ENODEV;
300	min = i2c_smbus_read_word_data(client, 4);
301	if (i2c_smbus_read_word_data(client, 6) != min
302	 || i2c_smbus_read_word_data(client, 7) != min)
303		return -ENODEV;
304
305	strscpy(info->type, "lm77", I2C_NAME_SIZE);
306
307	return 0;
308}
309
310static void lm77_init_client(struct i2c_client *client)
311{
312	/* Initialize the LM77 chip - turn off shutdown mode */
313	int conf = lm77_read_value(client, LM77_REG_CONF);
314	if (conf & 1)
315		lm77_write_value(client, LM77_REG_CONF, conf & 0xfe);
316}
317
318static int lm77_probe(struct i2c_client *client)
319{
320	struct device *dev = &client->dev;
321	struct device *hwmon_dev;
322	struct lm77_data *data;
323
324	data = devm_kzalloc(dev, sizeof(struct lm77_data), GFP_KERNEL);
325	if (!data)
326		return -ENOMEM;
327
328	data->client = client;
329	mutex_init(&data->update_lock);
330
331	/* Initialize the LM77 chip */
332	lm77_init_client(client);
333
334	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
335							   data, lm77_groups);
336	return PTR_ERR_OR_ZERO(hwmon_dev);
337}
338
339static const struct i2c_device_id lm77_id[] = {
340	{ "lm77", 0 },
341	{ }
342};
343MODULE_DEVICE_TABLE(i2c, lm77_id);
344
345/* This is the driver that will be inserted */
346static struct i2c_driver lm77_driver = {
347	.class		= I2C_CLASS_HWMON,
348	.driver = {
349		.name	= "lm77",
350	},
351	.probe		= lm77_probe,
352	.id_table	= lm77_id,
353	.detect		= lm77_detect,
354	.address_list	= normal_i2c,
355};
356
357module_i2c_driver(lm77_driver);
358
359MODULE_AUTHOR("Andras BALI <drewie@freemail.hu>");
360MODULE_DESCRIPTION("LM77 driver");
361MODULE_LICENSE("GPL");
362