blob: ba72347cb99d9242742792f2c3692ff150b9a921 [file] [log] [blame]
Kaiwan N Billimoria78961a52007-07-17 04:04:05 -07001/*
Grant Likelyca632f52011-06-06 01:16:30 -06002 * Driver for LM70EVAL-LLP board for the LM70 sensor
Kaiwan N Billimoria78961a52007-07-17 04:04:05 -07003 *
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.
Kaiwan N Billimoria78961a52007-07-17 04:04:05 -070015 */
16
17#include <linux/init.h>
18#include <linux/module.h>
19#include <linux/kernel.h>
20#include <linux/delay.h>
21#include <linux/device.h>
22#include <linux/parport.h>
23#include <linux/sysfs.h>
24#include <linux/workqueue.h>
25
26
27#include <linux/spi/spi.h>
28#include <linux/spi/spi_bitbang.h>
29
30
31/*
32 * The LM70 communicates with a host processor using a 3-wire variant of
33 * the SPI/Microwire bus interface. This driver specifically supports an
34 * NS LM70 LLP Evaluation Board, interfacing to a PC using its parallel
35 * port to bitbang an SPI-parport bridge. Accordingly, this is an SPI
36 * master controller driver. The hwmon/lm70 driver is a "SPI protocol
37 * driver", layered on top of this one and usable without the lm70llp.
38 *
Kaiwan N Billimoria2b730052009-01-07 16:37:34 +010039 * Datasheet and Schematic:
Kaiwan N Billimoria78961a52007-07-17 04:04:05 -070040 * The LM70 is a temperature sensor chip from National Semiconductor; its
41 * datasheet is available at http://www.national.com/pf/LM/LM70.html
Kaiwan N Billimoria2b730052009-01-07 16:37:34 +010042 * The schematic for this particular board (the LM70EVAL-LLP) is
43 * available (on page 4) here:
44 * http://www.national.com/appinfo/tempsensors/files/LM70LLPEVALmanual.pdf
Kaiwan N Billimoria78961a52007-07-17 04:04:05 -070045 *
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
Kaiwan N Billimoria2b730052009-01-07 16:37:34 +010067 * SI/SO signal (see the schematic for details).
Kaiwan N Billimoria78961a52007-07-17 04:04:05 -070068 */
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
79struct 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;
Tony Jones49dce682007-10-16 01:27:48 -070085 //struct device *dev;
Kaiwan N Billimoria78961a52007-07-17 04:04:05 -070086};
87
88/* REVISIT : ugly global ; provides "exclusive open" facility */
89static struct spi_lm70llp *lm70llp;
90
91
92/*-------------------------------------------------------------------*/
93
94static 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
106static inline void deassertCS(struct spi_lm70llp *pp)
107{
108 u8 data = parport_read_data(pp->port);
Kaiwan N Billimoria2b730052009-01-07 16:37:34 +0100109
110 data &= ~0x80; /* pull D7/SI-out low while de-asserted */
Kaiwan N Billimoria78961a52007-07-17 04:04:05 -0700111 parport_write_data(pp->port, data | nCS);
112}
113
114static inline void assertCS(struct spi_lm70llp *pp)
115{
116 u8 data = parport_read_data(pp->port);
Kaiwan N Billimoria2b730052009-01-07 16:37:34 +0100117
118 data |= 0x80; /* pull D7/SI-out high so lm70 drives SO-in */
Kaiwan N Billimoria78961a52007-07-17 04:04:05 -0700119 parport_write_data(pp->port, data & ~nCS);
120}
121
122static inline void clkHigh(struct spi_lm70llp *pp)
123{
124 u8 data = parport_read_data(pp->port);
125 parport_write_data(pp->port, data | SCLK);
126}
127
128static inline void clkLow(struct spi_lm70llp *pp)
129{
130 u8 data = parport_read_data(pp->port);
131 parport_write_data(pp->port, data & ~SCLK);
132}
133
134/*------------------------- SPI-LM70-specific inlines ----------------------*/
135
136static inline void spidelay(unsigned d)
137{
138 udelay(d);
139}
140
141static inline void setsck(struct spi_device *s, int is_on)
142{
143 struct spi_lm70llp *pp = spidev_to_pp(s);
144
145 if (is_on)
146 clkHigh(pp);
147 else
148 clkLow(pp);
149}
150
151static inline void setmosi(struct spi_device *s, int is_on)
152{
153 /* FIXME update D7 ... this way we can put the chip
154 * into shutdown mode and read the manufacturer ID,
155 * but we can't put it back into operational mode.
156 */
157}
158
159/*
160 * getmiso:
161 * Why do we return 0 when the SIO line is high and vice-versa?
162 * The fact is, the lm70 eval board from NS (which this driver drives),
163 * is wired in just such a way : when the lm70's SIO goes high, a transistor
164 * switches it to low reflecting this on the parport (pin 13), and vice-versa.
165 */
166static inline int getmiso(struct spi_device *s)
167{
168 struct spi_lm70llp *pp = spidev_to_pp(s);
169 return ((SIO == (parport_read_status(pp->port) & SIO)) ? 0 : 1 );
170}
171/*--------------------------------------------------------------------*/
172
Grant Likelyca632f52011-06-06 01:16:30 -0600173#include "spi-bitbang-txrx.h"
Kaiwan N Billimoria78961a52007-07-17 04:04:05 -0700174
175static void lm70_chipselect(struct spi_device *spi, int value)
176{
177 struct spi_lm70llp *pp = spidev_to_pp(spi);
178
179 if (value)
180 assertCS(pp);
181 else
182 deassertCS(pp);
183}
184
185/*
186 * Our actual bitbanger routine.
187 */
188static u32 lm70_txrx(struct spi_device *spi, unsigned nsecs, u32 word, u8 bits)
189{
Marek Szyprowski04bb2a02010-06-30 14:27:32 -0600190 return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
Kaiwan N Billimoria78961a52007-07-17 04:04:05 -0700191}
192
193static void spi_lm70llp_attach(struct parport *p)
194{
195 struct pardevice *pd;
196 struct spi_lm70llp *pp;
197 struct spi_master *master;
198 int status;
199
200 if (lm70llp) {
201 printk(KERN_WARNING
202 "%s: spi_lm70llp instance already loaded. Aborting.\n",
203 DRVNAME);
204 return;
205 }
206
207 /* TODO: this just _assumes_ a lm70 is there ... no probe;
208 * the lm70 driver could verify it, reading the manf ID.
209 */
210
211 master = spi_alloc_master(p->physport->dev, sizeof *pp);
212 if (!master) {
213 status = -ENOMEM;
214 goto out_fail;
215 }
216 pp = spi_master_get_devdata(master);
217
Kaiwan N Billimoria78961a52007-07-17 04:04:05 -0700218 /*
219 * SPI and bitbang hookup.
220 */
Axel Lin94c69f72013-09-10 15:43:41 +0800221 pp->bitbang.master = master;
Kaiwan N Billimoria78961a52007-07-17 04:04:05 -0700222 pp->bitbang.chipselect = lm70_chipselect;
223 pp->bitbang.txrx_word[SPI_MODE_0] = lm70_txrx;
224 pp->bitbang.flags = SPI_3WIRE;
225
226 /*
227 * Parport hookup
228 */
229 pp->port = p;
230 pd = parport_register_device(p, DRVNAME,
231 NULL, NULL, NULL,
232 PARPORT_FLAG_EXCL, pp);
233 if (!pd) {
234 status = -ENOMEM;
235 goto out_free_master;
236 }
237 pp->pd = pd;
238
239 status = parport_claim(pd);
240 if (status < 0)
241 goto out_parport_unreg;
242
243 /*
244 * Start SPI ...
245 */
246 status = spi_bitbang_start(&pp->bitbang);
247 if (status < 0) {
248 printk(KERN_WARNING
249 "%s: spi_bitbang_start failed with status %d\n",
250 DRVNAME, status);
251 goto out_off_and_release;
252 }
253
254 /*
255 * The modalias name MUST match the device_driver name
256 * for the bus glue code to match and subsequently bind them.
257 * We are binding to the generic drivers/hwmon/lm70.c device
258 * driver.
259 */
260 strcpy(pp->info.modalias, "lm70");
261 pp->info.max_speed_hz = 6 * 1000 * 1000;
262 pp->info.chip_select = 0;
263 pp->info.mode = SPI_3WIRE | SPI_MODE_0;
264
265 /* power up the chip, and let the LM70 control SI/SO */
266 parport_write_data(pp->port, lm70_INIT);
267
268 /* Enable access to our primary data structure via
269 * the board info's (void *)controller_data.
270 */
271 pp->info.controller_data = pp;
272 pp->spidev_lm70 = spi_new_device(pp->bitbang.master, &pp->info);
273 if (pp->spidev_lm70)
274 dev_dbg(&pp->spidev_lm70->dev, "spidev_lm70 at %s\n",
Kay Sievers35f74fc2009-01-06 10:44:37 -0800275 dev_name(&pp->spidev_lm70->dev));
Kaiwan N Billimoria78961a52007-07-17 04:04:05 -0700276 else {
277 printk(KERN_WARNING "%s: spi_new_device failed\n", DRVNAME);
278 status = -ENODEV;
279 goto out_bitbang_stop;
280 }
Kaiwan N Billimoria2b730052009-01-07 16:37:34 +0100281 pp->spidev_lm70->bits_per_word = 8;
Kaiwan N Billimoria78961a52007-07-17 04:04:05 -0700282
283 lm70llp = pp;
Kaiwan N Billimoria78961a52007-07-17 04:04:05 -0700284 return;
285
286out_bitbang_stop:
287 spi_bitbang_stop(&pp->bitbang);
288out_off_and_release:
289 /* power down */
290 parport_write_data(pp->port, 0);
291 mdelay(10);
292 parport_release(pp->pd);
293out_parport_unreg:
294 parport_unregister_device(pd);
295out_free_master:
296 (void) spi_master_put(master);
297out_fail:
298 pr_info("%s: spi_lm70llp probe fail, status %d\n", DRVNAME, status);
299}
300
301static void spi_lm70llp_detach(struct parport *p)
302{
303 struct spi_lm70llp *pp;
304
305 if (!lm70llp || lm70llp->port != p)
306 return;
307
308 pp = lm70llp;
309 spi_bitbang_stop(&pp->bitbang);
310
311 /* power down */
312 parport_write_data(pp->port, 0);
Kaiwan N Billimoria78961a52007-07-17 04:04:05 -0700313
314 parport_release(pp->pd);
315 parport_unregister_device(pp->pd);
316
317 (void) spi_master_put(pp->bitbang.master);
318
319 lm70llp = NULL;
320}
321
322
323static struct parport_driver spi_lm70llp_drv = {
324 .name = DRVNAME,
325 .attach = spi_lm70llp_attach,
326 .detach = spi_lm70llp_detach,
327};
328
329static int __init init_spi_lm70llp(void)
330{
331 return parport_register_driver(&spi_lm70llp_drv);
332}
333module_init(init_spi_lm70llp);
334
335static void __exit cleanup_spi_lm70llp(void)
336{
337 parport_unregister_driver(&spi_lm70llp_drv);
338}
339module_exit(cleanup_spi_lm70llp);
340
341MODULE_AUTHOR("Kaiwan N Billimoria <kaiwan@designergraphix.com>");
342MODULE_DESCRIPTION(
343 "Parport adapter for the National Semiconductor LM70 LLP eval board");
344MODULE_LICENSE("GPL");