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ds1620.c
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1 /*
2  * linux/drivers/char/ds1620.c: Dallas Semiconductors DS1620
3  * thermometer driver (as used in the Rebel.com NetWinder)
4  */
5 #include <linux/module.h>
6 #include <linux/miscdevice.h>
7 #include <linux/delay.h>
8 #include <linux/proc_fs.h>
9 #include <linux/capability.h>
10 #include <linux/init.h>
11 #include <linux/mutex.h>
12 
13 #include <mach/hardware.h>
14 #include <asm/mach-types.h>
15 #include <asm/uaccess.h>
16 #include <asm/therm.h>
17 
18 #ifdef CONFIG_PROC_FS
19 /* define for /proc interface */
20 #define THERM_USE_PROC
21 #endif
22 
23 /* Definitions for DS1620 chip */
24 #define THERM_START_CONVERT 0xee
25 #define THERM_RESET 0xaf
26 #define THERM_READ_CONFIG 0xac
27 #define THERM_READ_TEMP 0xaa
28 #define THERM_READ_TL 0xa2
29 #define THERM_READ_TH 0xa1
30 #define THERM_WRITE_CONFIG 0x0c
31 #define THERM_WRITE_TL 0x02
32 #define THERM_WRITE_TH 0x01
33 
34 #define CFG_CPU 2
35 #define CFG_1SHOT 1
36 
37 static DEFINE_MUTEX(ds1620_mutex);
38 static const char *fan_state[] = { "off", "on", "on (hardwired)" };
39 
40 /*
41  * Start of NetWinder specifics
42  * Note! We have to hold the gpio lock with IRQs disabled over the
43  * whole of our transaction to the Dallas chip, since there is a
44  * chance that the WaveArtist driver could touch these bits to
45  * enable or disable the speaker.
46  */
47 extern unsigned int system_rev;
48 
49 static inline void netwinder_ds1620_set_clk(int clk)
50 {
52 }
53 
54 static inline void netwinder_ds1620_set_data(int dat)
55 {
57 }
58 
59 static inline int netwinder_ds1620_get_data(void)
60 {
61  return nw_gpio_read() & GPIO_DATA;
62 }
63 
64 static inline void netwinder_ds1620_set_data_dir(int dir)
65 {
67 }
68 
69 static inline void netwinder_ds1620_reset(void)
70 {
73 }
74 
75 static inline void netwinder_lock(unsigned long *flags)
76 {
77  raw_spin_lock_irqsave(&nw_gpio_lock, *flags);
78 }
79 
80 static inline void netwinder_unlock(unsigned long *flags)
81 {
82  raw_spin_unlock_irqrestore(&nw_gpio_lock, *flags);
83 }
84 
85 static inline void netwinder_set_fan(int i)
86 {
87  unsigned long flags;
88 
89  raw_spin_lock_irqsave(&nw_gpio_lock, flags);
91  raw_spin_unlock_irqrestore(&nw_gpio_lock, flags);
92 }
93 
94 static inline int netwinder_get_fan(void)
95 {
96  if ((system_rev & 0xf000) == 0x4000)
97  return FAN_ALWAYS_ON;
98 
99  return (nw_gpio_read() & GPIO_FAN) ? FAN_ON : FAN_OFF;
100 }
101 
102 /*
103  * End of NetWinder specifics
104  */
105 
106 static void ds1620_send_bits(int nr, int value)
107 {
108  int i;
109 
110  for (i = 0; i < nr; i++) {
111  netwinder_ds1620_set_data(value & 1);
112  netwinder_ds1620_set_clk(0);
113  udelay(1);
114  netwinder_ds1620_set_clk(1);
115  udelay(1);
116 
117  value >>= 1;
118  }
119 }
120 
121 static unsigned int ds1620_recv_bits(int nr)
122 {
123  unsigned int value = 0, mask = 1;
124  int i;
125 
126  netwinder_ds1620_set_data(0);
127 
128  for (i = 0; i < nr; i++) {
129  netwinder_ds1620_set_clk(0);
130  udelay(1);
131 
132  if (netwinder_ds1620_get_data())
133  value |= mask;
134 
135  mask <<= 1;
136 
137  netwinder_ds1620_set_clk(1);
138  udelay(1);
139  }
140 
141  return value;
142 }
143 
144 static void ds1620_out(int cmd, int bits, int value)
145 {
146  unsigned long flags;
147 
148  netwinder_lock(&flags);
149  netwinder_ds1620_set_clk(1);
150  netwinder_ds1620_set_data_dir(0);
151  netwinder_ds1620_reset();
152 
153  udelay(1);
154 
155  ds1620_send_bits(8, cmd);
156  if (bits)
157  ds1620_send_bits(bits, value);
158 
159  udelay(1);
160 
161  netwinder_ds1620_reset();
162  netwinder_unlock(&flags);
163 
164  msleep(20);
165 }
166 
167 static unsigned int ds1620_in(int cmd, int bits)
168 {
169  unsigned long flags;
170  unsigned int value;
171 
172  netwinder_lock(&flags);
173  netwinder_ds1620_set_clk(1);
174  netwinder_ds1620_set_data_dir(0);
175  netwinder_ds1620_reset();
176 
177  udelay(1);
178 
179  ds1620_send_bits(8, cmd);
180 
181  netwinder_ds1620_set_data_dir(1);
182  value = ds1620_recv_bits(bits);
183 
184  netwinder_ds1620_reset();
185  netwinder_unlock(&flags);
186 
187  return value;
188 }
189 
190 static int cvt_9_to_int(unsigned int val)
191 {
192  if (val & 0x100)
193  val |= 0xfffffe00;
194 
195  return val;
196 }
197 
198 static void ds1620_write_state(struct therm *therm)
199 {
200  ds1620_out(THERM_WRITE_CONFIG, 8, CFG_CPU);
201  ds1620_out(THERM_WRITE_TL, 9, therm->lo);
202  ds1620_out(THERM_WRITE_TH, 9, therm->hi);
203  ds1620_out(THERM_START_CONVERT, 0, 0);
204 }
205 
206 static void ds1620_read_state(struct therm *therm)
207 {
208  therm->lo = cvt_9_to_int(ds1620_in(THERM_READ_TL, 9));
209  therm->hi = cvt_9_to_int(ds1620_in(THERM_READ_TH, 9));
210 }
211 
212 static int ds1620_open(struct inode *inode, struct file *file)
213 {
214  return nonseekable_open(inode, file);
215 }
216 
217 static ssize_t
218 ds1620_read(struct file *file, char __user *buf, size_t count, loff_t *ptr)
219 {
220  signed int cur_temp;
221  signed char cur_temp_degF;
222 
223  cur_temp = cvt_9_to_int(ds1620_in(THERM_READ_TEMP, 9)) >> 1;
224 
225  /* convert to Fahrenheit, as per wdt.c */
226  cur_temp_degF = (cur_temp * 9) / 5 + 32;
227 
228  if (copy_to_user(buf, &cur_temp_degF, 1))
229  return -EFAULT;
230 
231  return 1;
232 }
233 
234 static int
235 ds1620_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
236 {
237  struct therm therm;
238  union {
239  struct therm __user *therm;
240  int __user *i;
241  } uarg;
242  int i;
243 
244  uarg.i = (int __user *)arg;
245 
246  switch(cmd) {
247  case CMD_SET_THERMOSTATE:
249  if (!capable(CAP_SYS_ADMIN))
250  return -EPERM;
251 
252  if (cmd == CMD_SET_THERMOSTATE) {
253  if (get_user(therm.hi, uarg.i))
254  return -EFAULT;
255  therm.lo = therm.hi - 3;
256  } else {
257  if (copy_from_user(&therm, uarg.therm, sizeof(therm)))
258  return -EFAULT;
259  }
260 
261  therm.lo <<= 1;
262  therm.hi <<= 1;
263 
264  ds1620_write_state(&therm);
265  break;
266 
267  case CMD_GET_THERMOSTATE:
269  ds1620_read_state(&therm);
270 
271  therm.lo >>= 1;
272  therm.hi >>= 1;
273 
274  if (cmd == CMD_GET_THERMOSTATE) {
275  if (put_user(therm.hi, uarg.i))
276  return -EFAULT;
277  } else {
278  if (copy_to_user(uarg.therm, &therm, sizeof(therm)))
279  return -EFAULT;
280  }
281  break;
282 
283  case CMD_GET_TEMPERATURE:
285  i = cvt_9_to_int(ds1620_in(THERM_READ_TEMP, 9));
286 
287  if (cmd == CMD_GET_TEMPERATURE)
288  i >>= 1;
289 
290  return put_user(i, uarg.i) ? -EFAULT : 0;
291 
292  case CMD_GET_STATUS:
293  i = ds1620_in(THERM_READ_CONFIG, 8) & 0xe3;
294 
295  return put_user(i, uarg.i) ? -EFAULT : 0;
296 
297  case CMD_GET_FAN:
298  i = netwinder_get_fan();
299 
300  return put_user(i, uarg.i) ? -EFAULT : 0;
301 
302  case CMD_SET_FAN:
303  if (!capable(CAP_SYS_ADMIN))
304  return -EPERM;
305 
306  if (get_user(i, uarg.i))
307  return -EFAULT;
308 
309  netwinder_set_fan(i);
310  break;
311 
312  default:
313  return -ENOIOCTLCMD;
314  }
315 
316  return 0;
317 }
318 
319 static long
320 ds1620_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
321 {
322  int ret;
323 
324  mutex_lock(&ds1620_mutex);
325  ret = ds1620_ioctl(file, cmd, arg);
326  mutex_unlock(&ds1620_mutex);
327 
328  return ret;
329 }
330 
331 #ifdef THERM_USE_PROC
332 static int
333 proc_therm_ds1620_read(char *buf, char **start, off_t offset,
334  int len, int *eof, void *unused)
335 {
336  struct therm th;
337  int temp;
338 
339  ds1620_read_state(&th);
340  temp = cvt_9_to_int(ds1620_in(THERM_READ_TEMP, 9));
341 
342  len = sprintf(buf, "Thermostat: HI %i.%i, LOW %i.%i; "
343  "temperature: %i.%i C, fan %s\n",
344  th.hi >> 1, th.hi & 1 ? 5 : 0,
345  th.lo >> 1, th.lo & 1 ? 5 : 0,
346  temp >> 1, temp & 1 ? 5 : 0,
347  fan_state[netwinder_get_fan()]);
348 
349  return len;
350 }
351 
352 static struct proc_dir_entry *proc_therm_ds1620;
353 #endif
354 
355 static const struct file_operations ds1620_fops = {
356  .owner = THIS_MODULE,
357  .open = ds1620_open,
358  .read = ds1620_read,
359  .unlocked_ioctl = ds1620_unlocked_ioctl,
360  .llseek = no_llseek,
361 };
362 
363 static struct miscdevice ds1620_miscdev = {
364  TEMP_MINOR,
365  "temp",
366  &ds1620_fops
367 };
368 
369 static int __init ds1620_init(void)
370 {
371  int ret;
372  struct therm th, th_start;
373 
374  if (!machine_is_netwinder())
375  return -ENODEV;
376 
377  ds1620_out(THERM_RESET, 0, 0);
378  ds1620_out(THERM_WRITE_CONFIG, 8, CFG_CPU);
379  ds1620_out(THERM_START_CONVERT, 0, 0);
380 
381  /*
382  * Trigger the fan to start by setting
383  * temperature high point low. This kicks
384  * the fan into action.
385  */
386  ds1620_read_state(&th);
387  th_start.lo = 0;
388  th_start.hi = 1;
389  ds1620_write_state(&th_start);
390 
391  msleep(2000);
392 
393  ds1620_write_state(&th);
394 
395  ret = misc_register(&ds1620_miscdev);
396  if (ret < 0)
397  return ret;
398 
399 #ifdef THERM_USE_PROC
400  proc_therm_ds1620 = create_proc_entry("therm", 0, NULL);
401  if (proc_therm_ds1620)
402  proc_therm_ds1620->read_proc = proc_therm_ds1620_read;
403  else
404  printk(KERN_ERR "therm: unable to register /proc/therm\n");
405 #endif
406 
407  ds1620_read_state(&th);
408  ret = cvt_9_to_int(ds1620_in(THERM_READ_TEMP, 9));
409 
410  printk(KERN_INFO "Thermostat: high %i.%i, low %i.%i, "
411  "current %i.%i C, fan %s.\n",
412  th.hi >> 1, th.hi & 1 ? 5 : 0,
413  th.lo >> 1, th.lo & 1 ? 5 : 0,
414  ret >> 1, ret & 1 ? 5 : 0,
415  fan_state[netwinder_get_fan()]);
416 
417  return 0;
418 }
419 
420 static void __exit ds1620_exit(void)
421 {
422 #ifdef THERM_USE_PROC
423  remove_proc_entry("therm", NULL);
424 #endif
425  misc_deregister(&ds1620_miscdev);
426 }
427 
428 module_init(ds1620_init);
429 module_exit(ds1620_exit);
430 
431 MODULE_LICENSE("GPL");