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authorKaiwan N Billimoria <kaiwan@designergraphix.com>2007-07-17 07:04:05 -0400
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-17 13:23:04 -0400
commit78961a5740374a8143f8fe120300f2ed160dd276 (patch)
treefccfe279a3c01f139bc845f6c1e9575e8e0efd94
parent4917d927809918f0070bd1077b41e3daf78643b2 (diff)
spi_lm70llp parport adapter driver
This adds a driver for the LM70-LLP parport adapter, which is an eval board for the LM70 temperature sensor. For those without that board, it may be a simpler example of a parport-to-SPI adapter then spi_butterfly. Signed-off-by: Kaiwan N Billimoria <kaiwan@designergraphix.com> Doc, coding style, and interface updates; build fixes. Minor rename. Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--Documentation/spi/spi-lm70llp69
-rw-r--r--drivers/spi/Kconfig9
-rw-r--r--drivers/spi/Makefile1
-rw-r--r--drivers/spi/spi_lm70llp.c361
4 files changed, 440 insertions, 0 deletions
diff --git a/Documentation/spi/spi-lm70llp b/Documentation/spi/spi-lm70llp
new file mode 100644
index 00000000000..154bd02220b
--- /dev/null
+++ b/Documentation/spi/spi-lm70llp
@@ -0,0 +1,69 @@
1spi_lm70llp : LM70-LLP parport-to-SPI adapter
2==============================================
3
4Supported board/chip:
5 * National Semiconductor LM70 LLP evaluation board
6 Datasheet: http://www.national.com/pf/LM/LM70.html
7
8Author:
9 Kaiwan N Billimoria <kaiwan@designergraphix.com>
10
11Description
12-----------
13This driver provides glue code connecting a National Semiconductor LM70 LLP
14temperature sensor evaluation board to the kernel's SPI core subsystem.
15
16In effect, this driver turns the parallel port interface on the eval board
17into a SPI bus with a single device, which will be driven by the generic
18LM70 driver (drivers/hwmon/lm70.c).
19
20The hardware interfacing on the LM70 LLP eval board is as follows:
21
22 Parallel LM70 LLP
23 Port Direction JP2 Header
24 ----------- --------- ----------------
25 D0 2 - -
26 D1 3 --> V+ 5
27 D2 4 --> V+ 5
28 D3 5 --> V+ 5
29 D4 6 --> V+ 5
30 D5 7 --> nCS 8
31 D6 8 --> SCLK 3
32 D7 9 --> SI/O 5
33 GND 25 - GND 7
34 Select 13 <-- SI/O 1
35 ----------- --------- ----------------
36
37Note that since the LM70 uses a "3-wire" variant of SPI, the SI/SO pin
38is connected to both pin D7 (as Master Out) and Select (as Master In)
39using an arrangment that lets either the parport or the LM70 pull the
40pin low. This can't be shared with true SPI devices, but other 3-wire
41devices might share the same SI/SO pin.
42
43The bitbanger routine in this driver (lm70_txrx) is called back from
44the bound "hwmon/lm70" protocol driver through its sysfs hook, using a
45spi_write_then_read() call. It performs Mode 0 (SPI/Microwire) bitbanging.
46The lm70 driver then inteprets the resulting digital temperature value
47and exports it through sysfs.
48
49A "gotcha": National Semiconductor's LM70 LLP eval board circuit schematic
50shows that the SI/O line from the LM70 chip is connected to the base of a
51transistor Q1 (and also a pullup, and a zener diode to D7); while the
52collector is tied to VCC.
53
54Interpreting this circuit, when the LM70 SI/O line is High (or tristate
55and not grounded by the host via D7), the transistor conducts and switches
56the collector to zero, which is reflected on pin 13 of the DB25 parport
57connector. When SI/O is Low (driven by the LM70 or the host) on the other
58hand, the transistor is cut off and the voltage tied to it's collector is
59reflected on pin 13 as a High level.
60
61So: the getmiso inline routine in this driver takes this fact into account,
62inverting the value read at pin 13.
63
64
65Thanks to
66---------
67o David Brownell for mentoring the SPI-side driver development.
68o Dr.Craig Hollabaugh for the (early) "manual" bitbanging driver version.
69o Nadir Billimoria for help interpreting the circuit schematic.
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 5e3f748f269..488b341d2af 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -107,6 +107,15 @@ config SPI_IMX
107 This enables using the Freescale iMX SPI controller in master 107 This enables using the Freescale iMX SPI controller in master
108 mode. 108 mode.
109 109
110config SPI_LM70_LLP
111 tristate "Parallel port adapter for LM70 eval board (DEVELOPMENT)"
112 depends on SPI_MASTER && PARPORT && EXPERIMENTAL
113 select SPI_BITBANG
114 help
115 This driver supports the NS LM70 LLP Evaluation Board,
116 which interfaces to an LM70 temperature sensor using
117 a parallel port.
118
110config SPI_MPC52xx_PSC 119config SPI_MPC52xx_PSC
111 tristate "Freescale MPC52xx PSC SPI controller" 120 tristate "Freescale MPC52xx PSC SPI controller"
112 depends on SPI_MASTER && PPC_MPC52xx && EXPERIMENTAL 121 depends on SPI_MASTER && PPC_MPC52xx && EXPERIMENTAL
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 5788d867de8..89293338f20 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -17,6 +17,7 @@ obj-$(CONFIG_SPI_BITBANG) += spi_bitbang.o
17obj-$(CONFIG_SPI_AU1550) += au1550_spi.o 17obj-$(CONFIG_SPI_AU1550) += au1550_spi.o
18obj-$(CONFIG_SPI_BUTTERFLY) += spi_butterfly.o 18obj-$(CONFIG_SPI_BUTTERFLY) += spi_butterfly.o
19obj-$(CONFIG_SPI_IMX) += spi_imx.o 19obj-$(CONFIG_SPI_IMX) += spi_imx.o
20obj-$(CONFIG_SPI_LM70_LLP) += spi_lm70llp.o
20obj-$(CONFIG_SPI_PXA2XX) += pxa2xx_spi.o 21obj-$(CONFIG_SPI_PXA2XX) += pxa2xx_spi.o
21obj-$(CONFIG_SPI_OMAP_UWIRE) += omap_uwire.o 22obj-$(CONFIG_SPI_OMAP_UWIRE) += omap_uwire.o
22obj-$(CONFIG_SPI_MPC52xx_PSC) += mpc52xx_psc_spi.o 23obj-$(CONFIG_SPI_MPC52xx_PSC) += mpc52xx_psc_spi.o
diff --git a/drivers/spi/spi_lm70llp.c b/drivers/spi/spi_lm70llp.c
new file mode 100644
index 00000000000..4ea68ac1611
--- /dev/null
+++ b/drivers/spi/spi_lm70llp.c
@@ -0,0 +1,361 @@
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
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;
85 struct class_device *cdev;
86};
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);
109 parport_write_data(pp->port, data | nCS);
110}
111
112static 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
118static 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
124static 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
132static inline void spidelay(unsigned d)
133{
134 udelay(d);
135}
136
137static 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
147static 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 */
162static 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
172static 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 */
185static 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
205static 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
302out_bitbang_stop:
303 spi_bitbang_stop(&pp->bitbang);
304out_off_and_release:
305 /* power down */
306 parport_write_data(pp->port, 0);
307 mdelay(10);
308 parport_release(pp->pd);
309out_parport_unreg:
310 parport_unregister_device(pd);
311out_free_master:
312 (void) spi_master_put(master);
313out_fail:
314 pr_info("%s: spi_lm70llp probe fail, status %d\n", DRVNAME, status);
315}
316
317static 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
340static struct parport_driver spi_lm70llp_drv = {
341 .name = DRVNAME,
342 .attach = spi_lm70llp_attach,
343 .detach = spi_lm70llp_detach,
344};
345
346static int __init init_spi_lm70llp(void)
347{
348 return parport_register_driver(&spi_lm70llp_drv);
349}
350module_init(init_spi_lm70llp);
351
352static void __exit cleanup_spi_lm70llp(void)
353{
354 parport_unregister_driver(&spi_lm70llp_drv);
355}
356module_exit(cleanup_spi_lm70llp);
357
358MODULE_AUTHOR("Kaiwan N Billimoria <kaiwan@designergraphix.com>");
359MODULE_DESCRIPTION(
360 "Parport adapter for the National Semiconductor LM70 LLP eval board");
361MODULE_LICENSE("GPL");