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1 | /* |
2 | * spi_lm70llp.c - driver for lm70llp eval board for the LM70 sensor | |
3 | * | |
4 | * Copyright (C) 2006 Kaiwan N Billimoria <kaiwan@designergraphix.com> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License as published by | |
8 | * the Free Software Foundation; either version 2 of the License, or | |
9 | * (at your option) any later version. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License | |
17 | * along with this program; if not, write to the Free Software | |
18 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
19 | */ | |
20 | ||
21 | #include <linux/init.h> | |
22 | #include <linux/module.h> | |
23 | #include <linux/kernel.h> | |
24 | #include <linux/delay.h> | |
25 | #include <linux/device.h> | |
26 | #include <linux/parport.h> | |
27 | #include <linux/sysfs.h> | |
28 | #include <linux/workqueue.h> | |
29 | ||
30 | ||
31 | #include <linux/spi/spi.h> | |
32 | #include <linux/spi/spi_bitbang.h> | |
33 | ||
34 | ||
35 | /* | |
36 | * The LM70 communicates with a host processor using a 3-wire variant of | |
37 | * the SPI/Microwire bus interface. This driver specifically supports an | |
38 | * NS LM70 LLP Evaluation Board, interfacing to a PC using its parallel | |
39 | * port to bitbang an SPI-parport bridge. Accordingly, this is an SPI | |
40 | * master controller driver. The hwmon/lm70 driver is a "SPI protocol | |
41 | * driver", layered on top of this one and usable without the lm70llp. | |
42 | * | |
43 | * The LM70 is a temperature sensor chip from National Semiconductor; its | |
44 | * datasheet is available at http://www.national.com/pf/LM/LM70.html | |
45 | * | |
46 | * Also see Documentation/spi/spi-lm70llp. The SPI<->parport code here is | |
47 | * (heavily) based on spi-butterfly by David Brownell. | |
48 | * | |
49 | * The LM70 LLP connects to the PC parallel port in the following manner: | |
50 | * | |
51 | * Parallel LM70 LLP | |
52 | * Port Direction JP2 Header | |
53 | * ----------- --------- ------------ | |
54 | * D0 2 - - | |
55 | * D1 3 --> V+ 5 | |
56 | * D2 4 --> V+ 5 | |
57 | * D3 5 --> V+ 5 | |
58 | * D4 6 --> V+ 5 | |
59 | * D5 7 --> nCS 8 | |
60 | * D6 8 --> SCLK 3 | |
61 | * D7 9 --> SI/O 5 | |
62 | * GND 25 - GND 7 | |
63 | * Select 13 <-- SI/O 1 | |
64 | * | |
65 | * Note that parport pin 13 actually gets inverted by the transistor | |
66 | * arrangement which lets either the parport or the LM70 drive the | |
67 | * SI/SO signal. | |
68 | */ | |
69 | ||
70 | #define DRVNAME "spi-lm70llp" | |
71 | ||
72 | #define lm70_INIT 0xBE | |
73 | #define SIO 0x10 | |
74 | #define nCS 0x20 | |
75 | #define SCLK 0x40 | |
76 | ||
77 | /*-------------------------------------------------------------------------*/ | |
78 | ||
79 | struct spi_lm70llp { | |
80 | struct spi_bitbang bitbang; | |
81 | struct parport *port; | |
82 | struct pardevice *pd; | |
83 | struct spi_device *spidev_lm70; | |
84 | struct spi_board_info info; | |
49dce689 | 85 | //struct device *dev; |
78961a57 KB |
86 | }; |
87 | ||
88 | /* REVISIT : ugly global ; provides "exclusive open" facility */ | |
89 | static struct spi_lm70llp *lm70llp; | |
90 | ||
91 | ||
92 | /*-------------------------------------------------------------------*/ | |
93 | ||
94 | static inline struct spi_lm70llp *spidev_to_pp(struct spi_device *spi) | |
95 | { | |
96 | return spi->controller_data; | |
97 | } | |
98 | ||
99 | /*---------------------- LM70 LLP eval board-specific inlines follow */ | |
100 | ||
101 | /* NOTE: we don't actually need to reread the output values, since they'll | |
102 | * still be what we wrote before. Plus, going through parport builds in | |
103 | * a ~1ms/operation delay; these SPI transfers could easily be faster. | |
104 | */ | |
105 | ||
106 | static inline void deassertCS(struct spi_lm70llp *pp) | |
107 | { | |
108 | u8 data = parport_read_data(pp->port); | |
109 | parport_write_data(pp->port, data | nCS); | |
110 | } | |
111 | ||
112 | static inline void assertCS(struct spi_lm70llp *pp) | |
113 | { | |
114 | u8 data = parport_read_data(pp->port); | |
115 | parport_write_data(pp->port, data & ~nCS); | |
116 | } | |
117 | ||
118 | static inline void clkHigh(struct spi_lm70llp *pp) | |
119 | { | |
120 | u8 data = parport_read_data(pp->port); | |
121 | parport_write_data(pp->port, data | SCLK); | |
122 | } | |
123 | ||
124 | static inline void clkLow(struct spi_lm70llp *pp) | |
125 | { | |
126 | u8 data = parport_read_data(pp->port); | |
127 | parport_write_data(pp->port, data & ~SCLK); | |
128 | } | |
129 | ||
130 | /*------------------------- SPI-LM70-specific inlines ----------------------*/ | |
131 | ||
132 | static inline void spidelay(unsigned d) | |
133 | { | |
134 | udelay(d); | |
135 | } | |
136 | ||
137 | static inline void setsck(struct spi_device *s, int is_on) | |
138 | { | |
139 | struct spi_lm70llp *pp = spidev_to_pp(s); | |
140 | ||
141 | if (is_on) | |
142 | clkHigh(pp); | |
143 | else | |
144 | clkLow(pp); | |
145 | } | |
146 | ||
147 | static inline void setmosi(struct spi_device *s, int is_on) | |
148 | { | |
149 | /* FIXME update D7 ... this way we can put the chip | |
150 | * into shutdown mode and read the manufacturer ID, | |
151 | * but we can't put it back into operational mode. | |
152 | */ | |
153 | } | |
154 | ||
155 | /* | |
156 | * getmiso: | |
157 | * Why do we return 0 when the SIO line is high and vice-versa? | |
158 | * The fact is, the lm70 eval board from NS (which this driver drives), | |
159 | * is wired in just such a way : when the lm70's SIO goes high, a transistor | |
160 | * switches it to low reflecting this on the parport (pin 13), and vice-versa. | |
161 | */ | |
162 | static inline int getmiso(struct spi_device *s) | |
163 | { | |
164 | struct spi_lm70llp *pp = spidev_to_pp(s); | |
165 | return ((SIO == (parport_read_status(pp->port) & SIO)) ? 0 : 1 ); | |
166 | } | |
167 | /*--------------------------------------------------------------------*/ | |
168 | ||
169 | #define EXPAND_BITBANG_TXRX 1 | |
170 | #include <linux/spi/spi_bitbang.h> | |
171 | ||
172 | static void lm70_chipselect(struct spi_device *spi, int value) | |
173 | { | |
174 | struct spi_lm70llp *pp = spidev_to_pp(spi); | |
175 | ||
176 | if (value) | |
177 | assertCS(pp); | |
178 | else | |
179 | deassertCS(pp); | |
180 | } | |
181 | ||
182 | /* | |
183 | * Our actual bitbanger routine. | |
184 | */ | |
185 | static u32 lm70_txrx(struct spi_device *spi, unsigned nsecs, u32 word, u8 bits) | |
186 | { | |
187 | static u32 sio=0; | |
188 | static int first_time=1; | |
189 | ||
190 | /* First time: perform SPI bitbang and return the LSB of | |
191 | * the result of the SPI call. | |
192 | */ | |
193 | if (first_time) { | |
194 | sio = bitbang_txrx_be_cpha0(spi, nsecs, 0, word, bits); | |
195 | first_time=0; | |
196 | return (sio & 0x00ff); | |
197 | } | |
198 | /* Return the MSB of the result of the SPI call */ | |
199 | else { | |
200 | first_time=1; | |
201 | return (sio >> 8); | |
202 | } | |
203 | } | |
204 | ||
205 | static void spi_lm70llp_attach(struct parport *p) | |
206 | { | |
207 | struct pardevice *pd; | |
208 | struct spi_lm70llp *pp; | |
209 | struct spi_master *master; | |
210 | int status; | |
211 | ||
212 | if (lm70llp) { | |
213 | printk(KERN_WARNING | |
214 | "%s: spi_lm70llp instance already loaded. Aborting.\n", | |
215 | DRVNAME); | |
216 | return; | |
217 | } | |
218 | ||
219 | /* TODO: this just _assumes_ a lm70 is there ... no probe; | |
220 | * the lm70 driver could verify it, reading the manf ID. | |
221 | */ | |
222 | ||
223 | master = spi_alloc_master(p->physport->dev, sizeof *pp); | |
224 | if (!master) { | |
225 | status = -ENOMEM; | |
226 | goto out_fail; | |
227 | } | |
228 | pp = spi_master_get_devdata(master); | |
229 | ||
230 | master->bus_num = -1; /* dynamic alloc of a bus number */ | |
231 | master->num_chipselect = 1; | |
232 | ||
233 | /* | |
234 | * SPI and bitbang hookup. | |
235 | */ | |
236 | pp->bitbang.master = spi_master_get(master); | |
237 | pp->bitbang.chipselect = lm70_chipselect; | |
238 | pp->bitbang.txrx_word[SPI_MODE_0] = lm70_txrx; | |
239 | pp->bitbang.flags = SPI_3WIRE; | |
240 | ||
241 | /* | |
242 | * Parport hookup | |
243 | */ | |
244 | pp->port = p; | |
245 | pd = parport_register_device(p, DRVNAME, | |
246 | NULL, NULL, NULL, | |
247 | PARPORT_FLAG_EXCL, pp); | |
248 | if (!pd) { | |
249 | status = -ENOMEM; | |
250 | goto out_free_master; | |
251 | } | |
252 | pp->pd = pd; | |
253 | ||
254 | status = parport_claim(pd); | |
255 | if (status < 0) | |
256 | goto out_parport_unreg; | |
257 | ||
258 | /* | |
259 | * Start SPI ... | |
260 | */ | |
261 | status = spi_bitbang_start(&pp->bitbang); | |
262 | if (status < 0) { | |
263 | printk(KERN_WARNING | |
264 | "%s: spi_bitbang_start failed with status %d\n", | |
265 | DRVNAME, status); | |
266 | goto out_off_and_release; | |
267 | } | |
268 | ||
269 | /* | |
270 | * The modalias name MUST match the device_driver name | |
271 | * for the bus glue code to match and subsequently bind them. | |
272 | * We are binding to the generic drivers/hwmon/lm70.c device | |
273 | * driver. | |
274 | */ | |
275 | strcpy(pp->info.modalias, "lm70"); | |
276 | pp->info.max_speed_hz = 6 * 1000 * 1000; | |
277 | pp->info.chip_select = 0; | |
278 | pp->info.mode = SPI_3WIRE | SPI_MODE_0; | |
279 | ||
280 | /* power up the chip, and let the LM70 control SI/SO */ | |
281 | parport_write_data(pp->port, lm70_INIT); | |
282 | ||
283 | /* Enable access to our primary data structure via | |
284 | * the board info's (void *)controller_data. | |
285 | */ | |
286 | pp->info.controller_data = pp; | |
287 | pp->spidev_lm70 = spi_new_device(pp->bitbang.master, &pp->info); | |
288 | if (pp->spidev_lm70) | |
289 | dev_dbg(&pp->spidev_lm70->dev, "spidev_lm70 at %s\n", | |
290 | pp->spidev_lm70->dev.bus_id); | |
291 | else { | |
292 | printk(KERN_WARNING "%s: spi_new_device failed\n", DRVNAME); | |
293 | status = -ENODEV; | |
294 | goto out_bitbang_stop; | |
295 | } | |
296 | pp->spidev_lm70->bits_per_word = 16; | |
297 | ||
298 | lm70llp = pp; | |
299 | ||
300 | return; | |
301 | ||
302 | out_bitbang_stop: | |
303 | spi_bitbang_stop(&pp->bitbang); | |
304 | out_off_and_release: | |
305 | /* power down */ | |
306 | parport_write_data(pp->port, 0); | |
307 | mdelay(10); | |
308 | parport_release(pp->pd); | |
309 | out_parport_unreg: | |
310 | parport_unregister_device(pd); | |
311 | out_free_master: | |
312 | (void) spi_master_put(master); | |
313 | out_fail: | |
314 | pr_info("%s: spi_lm70llp probe fail, status %d\n", DRVNAME, status); | |
315 | } | |
316 | ||
317 | static void spi_lm70llp_detach(struct parport *p) | |
318 | { | |
319 | struct spi_lm70llp *pp; | |
320 | ||
321 | if (!lm70llp || lm70llp->port != p) | |
322 | return; | |
323 | ||
324 | pp = lm70llp; | |
325 | spi_bitbang_stop(&pp->bitbang); | |
326 | ||
327 | /* power down */ | |
328 | parport_write_data(pp->port, 0); | |
329 | msleep(10); | |
330 | ||
331 | parport_release(pp->pd); | |
332 | parport_unregister_device(pp->pd); | |
333 | ||
334 | (void) spi_master_put(pp->bitbang.master); | |
335 | ||
336 | lm70llp = NULL; | |
337 | } | |
338 | ||
339 | ||
340 | static struct parport_driver spi_lm70llp_drv = { | |
341 | .name = DRVNAME, | |
342 | .attach = spi_lm70llp_attach, | |
343 | .detach = spi_lm70llp_detach, | |
344 | }; | |
345 | ||
346 | static int __init init_spi_lm70llp(void) | |
347 | { | |
348 | return parport_register_driver(&spi_lm70llp_drv); | |
349 | } | |
350 | module_init(init_spi_lm70llp); | |
351 | ||
352 | static void __exit cleanup_spi_lm70llp(void) | |
353 | { | |
354 | parport_unregister_driver(&spi_lm70llp_drv); | |
355 | } | |
356 | module_exit(cleanup_spi_lm70llp); | |
357 | ||
358 | MODULE_AUTHOR("Kaiwan N Billimoria <kaiwan@designergraphix.com>"); | |
359 | MODULE_DESCRIPTION( | |
360 | "Parport adapter for the National Semiconductor LM70 LLP eval board"); | |
361 | MODULE_LICENSE("GPL"); |