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c942fddf | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
78961a57 | 2 | /* |
ca632f55 | 3 | * Driver for LM70EVAL-LLP board for the LM70 sensor |
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4 | * |
5 | * Copyright (C) 2006 Kaiwan N Billimoria <kaiwan@designergraphix.com> | |
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6 | */ |
7 | ||
22de54a9 SM |
8 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
9 | ||
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10 | #include <linux/init.h> |
11 | #include <linux/module.h> | |
12 | #include <linux/kernel.h> | |
13 | #include <linux/delay.h> | |
14 | #include <linux/device.h> | |
15 | #include <linux/parport.h> | |
16 | #include <linux/sysfs.h> | |
17 | #include <linux/workqueue.h> | |
18 | ||
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19 | #include <linux/spi/spi.h> |
20 | #include <linux/spi/spi_bitbang.h> | |
21 | ||
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22 | /* |
23 | * The LM70 communicates with a host processor using a 3-wire variant of | |
24 | * the SPI/Microwire bus interface. This driver specifically supports an | |
25 | * NS LM70 LLP Evaluation Board, interfacing to a PC using its parallel | |
26 | * port to bitbang an SPI-parport bridge. Accordingly, this is an SPI | |
27 | * master controller driver. The hwmon/lm70 driver is a "SPI protocol | |
28 | * driver", layered on top of this one and usable without the lm70llp. | |
29 | * | |
2b730051 | 30 | * Datasheet and Schematic: |
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31 | * The LM70 is a temperature sensor chip from National Semiconductor; its |
32 | * datasheet is available at http://www.national.com/pf/LM/LM70.html | |
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33 | * The schematic for this particular board (the LM70EVAL-LLP) is |
34 | * available (on page 4) here: | |
35 | * http://www.national.com/appinfo/tempsensors/files/LM70LLPEVALmanual.pdf | |
78961a57 | 36 | * |
9cdd273e | 37 | * Also see Documentation/spi/spi-lm70llp.rst. The SPI<->parport code here is |
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38 | * (heavily) based on spi-butterfly by David Brownell. |
39 | * | |
40 | * The LM70 LLP connects to the PC parallel port in the following manner: | |
41 | * | |
42 | * Parallel LM70 LLP | |
43 | * Port Direction JP2 Header | |
44 | * ----------- --------- ------------ | |
45 | * D0 2 - - | |
46 | * D1 3 --> V+ 5 | |
47 | * D2 4 --> V+ 5 | |
48 | * D3 5 --> V+ 5 | |
49 | * D4 6 --> V+ 5 | |
50 | * D5 7 --> nCS 8 | |
51 | * D6 8 --> SCLK 3 | |
52 | * D7 9 --> SI/O 5 | |
53 | * GND 25 - GND 7 | |
54 | * Select 13 <-- SI/O 1 | |
55 | * | |
56 | * Note that parport pin 13 actually gets inverted by the transistor | |
57 | * arrangement which lets either the parport or the LM70 drive the | |
2b730051 | 58 | * SI/SO signal (see the schematic for details). |
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59 | */ |
60 | ||
61 | #define DRVNAME "spi-lm70llp" | |
62 | ||
63 | #define lm70_INIT 0xBE | |
64 | #define SIO 0x10 | |
65 | #define nCS 0x20 | |
66 | #define SCLK 0x40 | |
67 | ||
68 | /*-------------------------------------------------------------------------*/ | |
69 | ||
70 | struct spi_lm70llp { | |
71 | struct spi_bitbang bitbang; | |
72 | struct parport *port; | |
73 | struct pardevice *pd; | |
74 | struct spi_device *spidev_lm70; | |
75 | struct spi_board_info info; | |
49dce689 | 76 | //struct device *dev; |
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77 | }; |
78 | ||
79 | /* REVISIT : ugly global ; provides "exclusive open" facility */ | |
80 | static struct spi_lm70llp *lm70llp; | |
81 | ||
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82 | /*-------------------------------------------------------------------*/ |
83 | ||
84 | static inline struct spi_lm70llp *spidev_to_pp(struct spi_device *spi) | |
85 | { | |
86 | return spi->controller_data; | |
87 | } | |
88 | ||
89 | /*---------------------- LM70 LLP eval board-specific inlines follow */ | |
90 | ||
91 | /* NOTE: we don't actually need to reread the output values, since they'll | |
92 | * still be what we wrote before. Plus, going through parport builds in | |
93 | * a ~1ms/operation delay; these SPI transfers could easily be faster. | |
94 | */ | |
95 | ||
96 | static inline void deassertCS(struct spi_lm70llp *pp) | |
97 | { | |
98 | u8 data = parport_read_data(pp->port); | |
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99 | |
100 | data &= ~0x80; /* pull D7/SI-out low while de-asserted */ | |
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101 | parport_write_data(pp->port, data | nCS); |
102 | } | |
103 | ||
104 | static inline void assertCS(struct spi_lm70llp *pp) | |
105 | { | |
106 | u8 data = parport_read_data(pp->port); | |
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107 | |
108 | data |= 0x80; /* pull D7/SI-out high so lm70 drives SO-in */ | |
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109 | parport_write_data(pp->port, data & ~nCS); |
110 | } | |
111 | ||
112 | static inline void clkHigh(struct spi_lm70llp *pp) | |
113 | { | |
114 | u8 data = parport_read_data(pp->port); | |
832329d7 | 115 | |
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116 | parport_write_data(pp->port, data | SCLK); |
117 | } | |
118 | ||
119 | static inline void clkLow(struct spi_lm70llp *pp) | |
120 | { | |
121 | u8 data = parport_read_data(pp->port); | |
832329d7 | 122 | |
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123 | parport_write_data(pp->port, data & ~SCLK); |
124 | } | |
125 | ||
126 | /*------------------------- SPI-LM70-specific inlines ----------------------*/ | |
127 | ||
128 | static inline void spidelay(unsigned d) | |
129 | { | |
130 | udelay(d); | |
131 | } | |
132 | ||
133 | static inline void setsck(struct spi_device *s, int is_on) | |
134 | { | |
135 | struct spi_lm70llp *pp = spidev_to_pp(s); | |
136 | ||
137 | if (is_on) | |
138 | clkHigh(pp); | |
139 | else | |
140 | clkLow(pp); | |
141 | } | |
142 | ||
143 | static inline void setmosi(struct spi_device *s, int is_on) | |
144 | { | |
145 | /* FIXME update D7 ... this way we can put the chip | |
146 | * into shutdown mode and read the manufacturer ID, | |
147 | * but we can't put it back into operational mode. | |
148 | */ | |
149 | } | |
150 | ||
151 | /* | |
152 | * getmiso: | |
153 | * Why do we return 0 when the SIO line is high and vice-versa? | |
154 | * The fact is, the lm70 eval board from NS (which this driver drives), | |
155 | * is wired in just such a way : when the lm70's SIO goes high, a transistor | |
156 | * switches it to low reflecting this on the parport (pin 13), and vice-versa. | |
157 | */ | |
158 | static inline int getmiso(struct spi_device *s) | |
159 | { | |
160 | struct spi_lm70llp *pp = spidev_to_pp(s); | |
832329d7 | 161 | |
74bdced4 | 162 | return ((SIO == (parport_read_status(pp->port) & SIO)) ? 0 : 1); |
78961a57 | 163 | } |
832329d7 | 164 | |
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165 | /*--------------------------------------------------------------------*/ |
166 | ||
ca632f55 | 167 | #include "spi-bitbang-txrx.h" |
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168 | |
169 | static void lm70_chipselect(struct spi_device *spi, int value) | |
170 | { | |
171 | struct spi_lm70llp *pp = spidev_to_pp(spi); | |
172 | ||
173 | if (value) | |
174 | assertCS(pp); | |
175 | else | |
176 | deassertCS(pp); | |
177 | } | |
178 | ||
179 | /* | |
180 | * Our actual bitbanger routine. | |
181 | */ | |
304d3436 LB |
182 | static u32 lm70_txrx(struct spi_device *spi, unsigned nsecs, u32 word, u8 bits, |
183 | unsigned flags) | |
78961a57 | 184 | { |
304d3436 | 185 | return bitbang_txrx_be_cpha0(spi, nsecs, 0, flags, word, bits); |
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186 | } |
187 | ||
188 | static void spi_lm70llp_attach(struct parport *p) | |
189 | { | |
190 | struct pardevice *pd; | |
191 | struct spi_lm70llp *pp; | |
192 | struct spi_master *master; | |
193 | int status; | |
2baed30c | 194 | struct pardev_cb lm70llp_cb; |
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195 | |
196 | if (lm70llp) { | |
22de54a9 | 197 | pr_warn("spi_lm70llp instance already loaded. Aborting.\n"); |
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198 | return; |
199 | } | |
200 | ||
201 | /* TODO: this just _assumes_ a lm70 is there ... no probe; | |
202 | * the lm70 driver could verify it, reading the manf ID. | |
203 | */ | |
204 | ||
205 | master = spi_alloc_master(p->physport->dev, sizeof *pp); | |
206 | if (!master) { | |
207 | status = -ENOMEM; | |
208 | goto out_fail; | |
209 | } | |
210 | pp = spi_master_get_devdata(master); | |
211 | ||
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212 | /* |
213 | * SPI and bitbang hookup. | |
214 | */ | |
94c69f76 | 215 | pp->bitbang.master = master; |
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216 | pp->bitbang.chipselect = lm70_chipselect; |
217 | pp->bitbang.txrx_word[SPI_MODE_0] = lm70_txrx; | |
218 | pp->bitbang.flags = SPI_3WIRE; | |
219 | ||
220 | /* | |
221 | * Parport hookup | |
222 | */ | |
223 | pp->port = p; | |
2baed30c SM |
224 | memset(&lm70llp_cb, 0, sizeof(lm70llp_cb)); |
225 | lm70llp_cb.private = pp; | |
226 | lm70llp_cb.flags = PARPORT_FLAG_EXCL; | |
227 | pd = parport_register_dev_model(p, DRVNAME, &lm70llp_cb, 0); | |
228 | ||
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229 | if (!pd) { |
230 | status = -ENOMEM; | |
231 | goto out_free_master; | |
232 | } | |
233 | pp->pd = pd; | |
234 | ||
235 | status = parport_claim(pd); | |
236 | if (status < 0) | |
237 | goto out_parport_unreg; | |
238 | ||
239 | /* | |
240 | * Start SPI ... | |
241 | */ | |
242 | status = spi_bitbang_start(&pp->bitbang); | |
243 | if (status < 0) { | |
46c52c28 SM |
244 | dev_warn(&pd->dev, "spi_bitbang_start failed with status %d\n", |
245 | status); | |
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246 | goto out_off_and_release; |
247 | } | |
248 | ||
249 | /* | |
250 | * The modalias name MUST match the device_driver name | |
251 | * for the bus glue code to match and subsequently bind them. | |
252 | * We are binding to the generic drivers/hwmon/lm70.c device | |
253 | * driver. | |
254 | */ | |
255 | strcpy(pp->info.modalias, "lm70"); | |
256 | pp->info.max_speed_hz = 6 * 1000 * 1000; | |
257 | pp->info.chip_select = 0; | |
258 | pp->info.mode = SPI_3WIRE | SPI_MODE_0; | |
259 | ||
260 | /* power up the chip, and let the LM70 control SI/SO */ | |
261 | parport_write_data(pp->port, lm70_INIT); | |
262 | ||
263 | /* Enable access to our primary data structure via | |
264 | * the board info's (void *)controller_data. | |
265 | */ | |
266 | pp->info.controller_data = pp; | |
267 | pp->spidev_lm70 = spi_new_device(pp->bitbang.master, &pp->info); | |
268 | if (pp->spidev_lm70) | |
269 | dev_dbg(&pp->spidev_lm70->dev, "spidev_lm70 at %s\n", | |
44dc0fdd | 270 | dev_name(&pp->spidev_lm70->dev)); |
78961a57 | 271 | else { |
46c52c28 | 272 | dev_warn(&pd->dev, "spi_new_device failed\n"); |
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273 | status = -ENODEV; |
274 | goto out_bitbang_stop; | |
275 | } | |
2b730051 | 276 | pp->spidev_lm70->bits_per_word = 8; |
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277 | |
278 | lm70llp = pp; | |
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279 | return; |
280 | ||
281 | out_bitbang_stop: | |
282 | spi_bitbang_stop(&pp->bitbang); | |
283 | out_off_and_release: | |
284 | /* power down */ | |
285 | parport_write_data(pp->port, 0); | |
286 | mdelay(10); | |
287 | parport_release(pp->pd); | |
288 | out_parport_unreg: | |
289 | parport_unregister_device(pd); | |
290 | out_free_master: | |
25fb1a46 | 291 | spi_master_put(master); |
78961a57 | 292 | out_fail: |
22de54a9 | 293 | pr_info("spi_lm70llp probe fail, status %d\n", status); |
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294 | } |
295 | ||
296 | static void spi_lm70llp_detach(struct parport *p) | |
297 | { | |
298 | struct spi_lm70llp *pp; | |
299 | ||
300 | if (!lm70llp || lm70llp->port != p) | |
301 | return; | |
302 | ||
303 | pp = lm70llp; | |
304 | spi_bitbang_stop(&pp->bitbang); | |
305 | ||
306 | /* power down */ | |
307 | parport_write_data(pp->port, 0); | |
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308 | |
309 | parport_release(pp->pd); | |
310 | parport_unregister_device(pp->pd); | |
311 | ||
25fb1a46 | 312 | spi_master_put(pp->bitbang.master); |
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313 | |
314 | lm70llp = NULL; | |
315 | } | |
316 | ||
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317 | static struct parport_driver spi_lm70llp_drv = { |
318 | .name = DRVNAME, | |
2baed30c | 319 | .match_port = spi_lm70llp_attach, |
78961a57 | 320 | .detach = spi_lm70llp_detach, |
2baed30c | 321 | .devmodel = true, |
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322 | }; |
323 | ||
324 | static int __init init_spi_lm70llp(void) | |
325 | { | |
326 | return parport_register_driver(&spi_lm70llp_drv); | |
327 | } | |
328 | module_init(init_spi_lm70llp); | |
329 | ||
330 | static void __exit cleanup_spi_lm70llp(void) | |
331 | { | |
332 | parport_unregister_driver(&spi_lm70llp_drv); | |
333 | } | |
334 | module_exit(cleanup_spi_lm70llp); | |
335 | ||
336 | MODULE_AUTHOR("Kaiwan N Billimoria <kaiwan@designergraphix.com>"); | |
337 | MODULE_DESCRIPTION( | |
338 | "Parport adapter for the National Semiconductor LM70 LLP eval board"); | |
339 | MODULE_LICENSE("GPL"); |