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 #include "spi_bitbang_txrx.h"
178
lm70_chipselect(struct spi_device * spi,int value)179 static void lm70_chipselect(struct spi_device *spi, int value)
180 {
181 struct spi_lm70llp *pp = spidev_to_pp(spi);
182
183 if (value)
184 assertCS(pp);
185 else
186 deassertCS(pp);
187 }
188
189 /*
190 * Our actual bitbanger routine.
191 */
lm70_txrx(struct spi_device * spi,unsigned nsecs,u32 word,u8 bits)192 static u32 lm70_txrx(struct spi_device *spi, unsigned nsecs, u32 word, u8 bits)
193 {
194 return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
195 }
196
spi_lm70llp_attach(struct parport * p)197 static void spi_lm70llp_attach(struct parport *p)
198 {
199 struct pardevice *pd;
200 struct spi_lm70llp *pp;
201 struct spi_master *master;
202 int status;
203
204 if (lm70llp) {
205 printk(KERN_WARNING
206 "%s: spi_lm70llp instance already loaded. Aborting.\n",
207 DRVNAME);
208 return;
209 }
210
211 /* TODO: this just _assumes_ a lm70 is there ... no probe;
212 * the lm70 driver could verify it, reading the manf ID.
213 */
214
215 master = spi_alloc_master(p->physport->dev, sizeof *pp);
216 if (!master) {
217 status = -ENOMEM;
218 goto out_fail;
219 }
220 pp = spi_master_get_devdata(master);
221
222 master->bus_num = -1; /* dynamic alloc of a bus number */
223 master->num_chipselect = 1;
224
225 /*
226 * SPI and bitbang hookup.
227 */
228 pp->bitbang.master = spi_master_get(master);
229 pp->bitbang.chipselect = lm70_chipselect;
230 pp->bitbang.txrx_word[SPI_MODE_0] = lm70_txrx;
231 pp->bitbang.flags = SPI_3WIRE;
232
233 /*
234 * Parport hookup
235 */
236 pp->port = p;
237 pd = parport_register_device(p, DRVNAME,
238 NULL, NULL, NULL,
239 PARPORT_FLAG_EXCL, pp);
240 if (!pd) {
241 status = -ENOMEM;
242 goto out_free_master;
243 }
244 pp->pd = pd;
245
246 status = parport_claim(pd);
247 if (status < 0)
248 goto out_parport_unreg;
249
250 /*
251 * Start SPI ...
252 */
253 status = spi_bitbang_start(&pp->bitbang);
254 if (status < 0) {
255 printk(KERN_WARNING
256 "%s: spi_bitbang_start failed with status %d\n",
257 DRVNAME, status);
258 goto out_off_and_release;
259 }
260
261 /*
262 * The modalias name MUST match the device_driver name
263 * for the bus glue code to match and subsequently bind them.
264 * We are binding to the generic drivers/hwmon/lm70.c device
265 * driver.
266 */
267 strcpy(pp->info.modalias, "lm70");
268 pp->info.max_speed_hz = 6 * 1000 * 1000;
269 pp->info.chip_select = 0;
270 pp->info.mode = SPI_3WIRE | SPI_MODE_0;
271
272 /* power up the chip, and let the LM70 control SI/SO */
273 parport_write_data(pp->port, lm70_INIT);
274
275 /* Enable access to our primary data structure via
276 * the board info's (void *)controller_data.
277 */
278 pp->info.controller_data = pp;
279 pp->spidev_lm70 = spi_new_device(pp->bitbang.master, &pp->info);
280 if (pp->spidev_lm70)
281 dev_dbg(&pp->spidev_lm70->dev, "spidev_lm70 at %s\n",
282 dev_name(&pp->spidev_lm70->dev));
283 else {
284 printk(KERN_WARNING "%s: spi_new_device failed\n", DRVNAME);
285 status = -ENODEV;
286 goto out_bitbang_stop;
287 }
288 pp->spidev_lm70->bits_per_word = 8;
289
290 lm70llp = pp;
291 return;
292
293 out_bitbang_stop:
294 spi_bitbang_stop(&pp->bitbang);
295 out_off_and_release:
296 /* power down */
297 parport_write_data(pp->port, 0);
298 mdelay(10);
299 parport_release(pp->pd);
300 out_parport_unreg:
301 parport_unregister_device(pd);
302 out_free_master:
303 (void) spi_master_put(master);
304 out_fail:
305 pr_info("%s: spi_lm70llp probe fail, status %d\n", DRVNAME, status);
306 }
307
spi_lm70llp_detach(struct parport * p)308 static void spi_lm70llp_detach(struct parport *p)
309 {
310 struct spi_lm70llp *pp;
311
312 if (!lm70llp || lm70llp->port != p)
313 return;
314
315 pp = lm70llp;
316 spi_bitbang_stop(&pp->bitbang);
317
318 /* power down */
319 parport_write_data(pp->port, 0);
320
321 parport_release(pp->pd);
322 parport_unregister_device(pp->pd);
323
324 (void) spi_master_put(pp->bitbang.master);
325
326 lm70llp = NULL;
327 }
328
329
330 static struct parport_driver spi_lm70llp_drv = {
331 .name = DRVNAME,
332 .attach = spi_lm70llp_attach,
333 .detach = spi_lm70llp_detach,
334 };
335
init_spi_lm70llp(void)336 static int __init init_spi_lm70llp(void)
337 {
338 return parport_register_driver(&spi_lm70llp_drv);
339 }
340 module_init(init_spi_lm70llp);
341
cleanup_spi_lm70llp(void)342 static void __exit cleanup_spi_lm70llp(void)
343 {
344 parport_unregister_driver(&spi_lm70llp_drv);
345 }
346 module_exit(cleanup_spi_lm70llp);
347
348 MODULE_AUTHOR("Kaiwan N Billimoria <kaiwan@designergraphix.com>");
349 MODULE_DESCRIPTION(
350 "Parport adapter for the National Semiconductor LM70 LLP eval board");
351 MODULE_LICENSE("GPL");
352