1 /*
2 * spi_lm70llp.c - driver for LM70EVAL-LLP 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 * Datasheet and Schematic:
44 * The LM70 is a temperature sensor chip from National Semiconductor; its
45 * datasheet is available at http://www.national.com/pf/LM/LM70.html
46 * The schematic for this particular board (the LM70EVAL-LLP) is
47 * available (on page 4) here:
48 * http://www.national.com/appinfo/tempsensors/files/LM70LLPEVALmanual.pdf
49 *
50 * Also see Documentation/spi/spi-lm70llp. The SPI<->parport code here is
51 * (heavily) based on spi-butterfly by David Brownell.
52 *
53 * The LM70 LLP connects to the PC parallel port in the following manner:
54 *
55 * Parallel LM70 LLP
56 * Port Direction JP2 Header
57 * ----------- --------- ------------
58 * D0 2 - -
59 * D1 3 --> V+ 5
60 * D2 4 --> V+ 5
61 * D3 5 --> V+ 5
62 * D4 6 --> V+ 5
63 * D5 7 --> nCS 8
64 * D6 8 --> SCLK 3
65 * D7 9 --> SI/O 5
66 * GND 25 - GND 7
67 * Select 13 <-- SI/O 1
68 *
69 * Note that parport pin 13 actually gets inverted by the transistor
70 * arrangement which lets either the parport or the LM70 drive the
71 * SI/SO signal (see the schematic for details).
72 */
73
74 #define DRVNAME "spi-lm70llp"
75
76 #define lm70_INIT 0xBE
77 #define SIO 0x10
78 #define nCS 0x20
79 #define SCLK 0x40
80
81 /*-------------------------------------------------------------------------*/
82
83 struct spi_lm70llp {
84 struct spi_bitbang bitbang;
85 struct parport *port;
86 struct pardevice *pd;
87 struct spi_device *spidev_lm70;
88 struct spi_board_info info;
89 //struct device *dev;
90 };
91
92 /* REVISIT : ugly global ; provides "exclusive open" facility */
93 static struct spi_lm70llp *lm70llp;
94
95
96 /*-------------------------------------------------------------------*/
97
spidev_to_pp(struct spi_device * spi)98 static inline struct spi_lm70llp *spidev_to_pp(struct spi_device *spi)
99 {
100 return spi->controller_data;
101 }
102
103 /*---------------------- LM70 LLP eval board-specific inlines follow */
104
105 /* NOTE: we don't actually need to reread the output values, since they'll
106 * still be what we wrote before. Plus, going through parport builds in
107 * a ~1ms/operation delay; these SPI transfers could easily be faster.
108 */
109
deassertCS(struct spi_lm70llp * pp)110 static inline void deassertCS(struct spi_lm70llp *pp)
111 {
112 u8 data = parport_read_data(pp->port);
113
114 data &= ~0x80; /* pull D7/SI-out low while de-asserted */
115 parport_write_data(pp->port, data | nCS);
116 }
117
assertCS(struct spi_lm70llp * pp)118 static inline void assertCS(struct spi_lm70llp *pp)
119 {
120 u8 data = parport_read_data(pp->port);
121
122 data |= 0x80; /* pull D7/SI-out high so lm70 drives SO-in */
123 parport_write_data(pp->port, data & ~nCS);
124 }
125
clkHigh(struct spi_lm70llp * pp)126 static inline void clkHigh(struct spi_lm70llp *pp)
127 {
128 u8 data = parport_read_data(pp->port);
129 parport_write_data(pp->port, data | SCLK);
130 }
131
clkLow(struct spi_lm70llp * pp)132 static inline void clkLow(struct spi_lm70llp *pp)
133 {
134 u8 data = parport_read_data(pp->port);
135 parport_write_data(pp->port, data & ~SCLK);
136 }
137
138 /*------------------------- SPI-LM70-specific inlines ----------------------*/
139
spidelay(unsigned d)140 static inline void spidelay(unsigned d)
141 {
142 udelay(d);
143 }
144
setsck(struct spi_device * s,int is_on)145 static inline void setsck(struct spi_device *s, int is_on)
146 {
147 struct spi_lm70llp *pp = spidev_to_pp(s);
148
149 if (is_on)
150 clkHigh(pp);
151 else
152 clkLow(pp);
153 }
154
setmosi(struct spi_device * s,int is_on)155 static inline void setmosi(struct spi_device *s, int is_on)
156 {
157 /* FIXME update D7 ... this way we can put the chip
158 * into shutdown mode and read the manufacturer ID,
159 * but we can't put it back into operational mode.
160 */
161 }
162
163 /*
164 * getmiso:
165 * Why do we return 0 when the SIO line is high and vice-versa?
166 * The fact is, the lm70 eval board from NS (which this driver drives),
167 * is wired in just such a way : when the lm70's SIO goes high, a transistor
168 * switches it to low reflecting this on the parport (pin 13), and vice-versa.
169 */
getmiso(struct spi_device * s)170 static inline int getmiso(struct spi_device *s)
171 {
172 struct spi_lm70llp *pp = spidev_to_pp(s);
173 return ((SIO == (parport_read_status(pp->port) & SIO)) ? 0 : 1 );
174 }
175 /*--------------------------------------------------------------------*/
176
177 #define EXPAND_BITBANG_TXRX 1
178 #include <linux/spi/spi_bitbang.h>
179
lm70_chipselect(struct spi_device * spi,int value)180 static void lm70_chipselect(struct spi_device *spi, int value)
181 {
182 struct spi_lm70llp *pp = spidev_to_pp(spi);
183
184 if (value)
185 assertCS(pp);
186 else
187 deassertCS(pp);
188 }
189
190 /*
191 * Our actual bitbanger routine.
192 */
lm70_txrx(struct spi_device * spi,unsigned nsecs,u32 word,u8 bits)193 static u32 lm70_txrx(struct spi_device *spi, unsigned nsecs, u32 word, u8 bits)
194 {
195 return bitbang_txrx_be_cpha0(spi, nsecs, 0, word, bits);
196 }
197
spi_lm70llp_attach(struct parport * p)198 static void spi_lm70llp_attach(struct parport *p)
199 {
200 struct pardevice *pd;
201 struct spi_lm70llp *pp;
202 struct spi_master *master;
203 int status;
204
205 if (lm70llp) {
206 printk(KERN_WARNING
207 "%s: spi_lm70llp instance already loaded. Aborting.\n",
208 DRVNAME);
209 return;
210 }
211
212 /* TODO: this just _assumes_ a lm70 is there ... no probe;
213 * the lm70 driver could verify it, reading the manf ID.
214 */
215
216 master = spi_alloc_master(p->physport->dev, sizeof *pp);
217 if (!master) {
218 status = -ENOMEM;
219 goto out_fail;
220 }
221 pp = spi_master_get_devdata(master);
222
223 master->bus_num = -1; /* dynamic alloc of a bus number */
224 master->num_chipselect = 1;
225
226 /*
227 * SPI and bitbang hookup.
228 */
229 pp->bitbang.master = spi_master_get(master);
230 pp->bitbang.chipselect = lm70_chipselect;
231 pp->bitbang.txrx_word[SPI_MODE_0] = lm70_txrx;
232 pp->bitbang.flags = SPI_3WIRE;
233
234 /*
235 * Parport hookup
236 */
237 pp->port = p;
238 pd = parport_register_device(p, DRVNAME,
239 NULL, NULL, NULL,
240 PARPORT_FLAG_EXCL, pp);
241 if (!pd) {
242 status = -ENOMEM;
243 goto out_free_master;
244 }
245 pp->pd = pd;
246
247 status = parport_claim(pd);
248 if (status < 0)
249 goto out_parport_unreg;
250
251 /*
252 * Start SPI ...
253 */
254 status = spi_bitbang_start(&pp->bitbang);
255 if (status < 0) {
256 printk(KERN_WARNING
257 "%s: spi_bitbang_start failed with status %d\n",
258 DRVNAME, status);
259 goto out_off_and_release;
260 }
261
262 /*
263 * The modalias name MUST match the device_driver name
264 * for the bus glue code to match and subsequently bind them.
265 * We are binding to the generic drivers/hwmon/lm70.c device
266 * driver.
267 */
268 strcpy(pp->info.modalias, "lm70");
269 pp->info.max_speed_hz = 6 * 1000 * 1000;
270 pp->info.chip_select = 0;
271 pp->info.mode = SPI_3WIRE | SPI_MODE_0;
272
273 /* power up the chip, and let the LM70 control SI/SO */
274 parport_write_data(pp->port, lm70_INIT);
275
276 /* Enable access to our primary data structure via
277 * the board info's (void *)controller_data.
278 */
279 pp->info.controller_data = pp;
280 pp->spidev_lm70 = spi_new_device(pp->bitbang.master, &pp->info);
281 if (pp->spidev_lm70)
282 dev_dbg(&pp->spidev_lm70->dev, "spidev_lm70 at %s\n",
283 dev_name(&pp->spidev_lm70->dev));
284 else {
285 printk(KERN_WARNING "%s: spi_new_device failed\n", DRVNAME);
286 status = -ENODEV;
287 goto out_bitbang_stop;
288 }
289 pp->spidev_lm70->bits_per_word = 8;
290
291 lm70llp = pp;
292 return;
293
294 out_bitbang_stop:
295 spi_bitbang_stop(&pp->bitbang);
296 out_off_and_release:
297 /* power down */
298 parport_write_data(pp->port, 0);
299 mdelay(10);
300 parport_release(pp->pd);
301 out_parport_unreg:
302 parport_unregister_device(pd);
303 out_free_master:
304 (void) spi_master_put(master);
305 out_fail:
306 pr_info("%s: spi_lm70llp probe fail, status %d\n", DRVNAME, status);
307 }
308
spi_lm70llp_detach(struct parport * p)309 static void spi_lm70llp_detach(struct parport *p)
310 {
311 struct spi_lm70llp *pp;
312
313 if (!lm70llp || lm70llp->port != p)
314 return;
315
316 pp = lm70llp;
317 spi_bitbang_stop(&pp->bitbang);
318
319 /* power down */
320 parport_write_data(pp->port, 0);
321
322 parport_release(pp->pd);
323 parport_unregister_device(pp->pd);
324
325 (void) spi_master_put(pp->bitbang.master);
326
327 lm70llp = NULL;
328 }
329
330
331 static struct parport_driver spi_lm70llp_drv = {
332 .name = DRVNAME,
333 .attach = spi_lm70llp_attach,
334 .detach = spi_lm70llp_detach,
335 };
336
init_spi_lm70llp(void)337 static int __init init_spi_lm70llp(void)
338 {
339 return parport_register_driver(&spi_lm70llp_drv);
340 }
341 module_init(init_spi_lm70llp);
342
cleanup_spi_lm70llp(void)343 static void __exit cleanup_spi_lm70llp(void)
344 {
345 parport_unregister_driver(&spi_lm70llp_drv);
346 }
347 module_exit(cleanup_spi_lm70llp);
348
349 MODULE_AUTHOR("Kaiwan N Billimoria <kaiwan@designergraphix.com>");
350 MODULE_DESCRIPTION(
351 "Parport adapter for the National Semiconductor LM70 LLP eval board");
352 MODULE_LICENSE("GPL");
353