1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * Driver for LM70EVAL-LLP board for the LM70 sensor |
4 | * |
5 | * Copyright (C) 2006 Kaiwan N Billimoria <kaiwan@designergraphix.com> |
6 | */ |
7 | |
8 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
9 | |
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 | |
19 | #include <linux/spi/spi.h> |
20 | #include <linux/spi/spi_bitbang.h> |
21 | |
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 | * host controller driver. The hwmon/lm70 driver is a "SPI protocol |
28 | * driver", layered on top of this one and usable without the lm70llp. |
29 | * |
30 | * Datasheet and Schematic: |
31 | * The LM70 is a temperature sensor chip from National Semiconductor; its |
32 | * datasheet is available at https://www.ti.com/lit/gpn/lm70 |
33 | * The schematic for this particular board (the LM70EVAL-LLP) is |
34 | * available (on page 4) here: |
35 | * https://download.datasheets.com/pdfs/documentation/nat/kit&board/lm70llpevalmanual.pdf |
36 | * |
37 | * Also see Documentation/spi/spi-lm70llp.rst. The SPI<->parport code here is |
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 |
58 | * SI/SO signal (see the schematic for details). |
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; |
76 | //struct device *dev; |
77 | }; |
78 | |
79 | /* REVISIT : ugly global ; provides "exclusive open" facility */ |
80 | static struct spi_lm70llp *lm70llp; |
81 | |
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); |
99 | |
100 | data &= ~0x80; /* pull D7/SI-out low while de-asserted */ |
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); |
107 | |
108 | data |= 0x80; /* pull D7/SI-out high so lm70 drives SO-in */ |
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); |
115 | |
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); |
122 | |
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(spi: 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(spi: s); |
161 | |
162 | return ((SIO == (parport_read_status(pp->port) & SIO)) ? 0 : 1); |
163 | } |
164 | |
165 | /*--------------------------------------------------------------------*/ |
166 | |
167 | #include "spi-bitbang-txrx.h" |
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 | */ |
182 | static u32 lm70_txrx(struct spi_device *spi, unsigned nsecs, u32 word, u8 bits, |
183 | unsigned flags) |
184 | { |
185 | return bitbang_txrx_be_cpha0(spi, nsecs, cpol: 0, flags, word, bits); |
186 | } |
187 | |
188 | static void spi_lm70llp_attach(struct parport *p) |
189 | { |
190 | struct pardevice *pd; |
191 | struct spi_lm70llp *pp; |
192 | struct spi_controller *host; |
193 | int status; |
194 | struct pardev_cb lm70llp_cb; |
195 | |
196 | if (lm70llp) { |
197 | pr_warn("spi_lm70llp instance already loaded. Aborting.\n" ); |
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 | host = spi_alloc_host(dev: p->physport->dev, size: sizeof(*pp)); |
206 | if (!host) { |
207 | status = -ENOMEM; |
208 | goto out_fail; |
209 | } |
210 | pp = spi_controller_get_devdata(ctlr: host); |
211 | |
212 | /* |
213 | * SPI and bitbang hookup. |
214 | */ |
215 | pp->bitbang.ctlr = host; |
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; |
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(port: p, DRVNAME, par_dev_cb: &lm70llp_cb, cnt: 0); |
228 | |
229 | if (!pd) { |
230 | status = -ENOMEM; |
231 | goto out_free_host; |
232 | } |
233 | pp->pd = pd; |
234 | |
235 | status = parport_claim(dev: pd); |
236 | if (status < 0) |
237 | goto out_parport_unreg; |
238 | |
239 | /* |
240 | * Start SPI ... |
241 | */ |
242 | status = spi_bitbang_start(spi: &pp->bitbang); |
243 | if (status < 0) { |
244 | dev_warn(&pd->dev, "spi_bitbang_start failed with status %d\n" , |
245 | status); |
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(p: pp->info.modalias, q: "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.ctlr, &pp->info); |
268 | if (pp->spidev_lm70) |
269 | dev_dbg(&pp->spidev_lm70->dev, "spidev_lm70 at %s\n" , |
270 | dev_name(&pp->spidev_lm70->dev)); |
271 | else { |
272 | dev_warn(&pd->dev, "spi_new_device failed\n" ); |
273 | status = -ENODEV; |
274 | goto out_bitbang_stop; |
275 | } |
276 | pp->spidev_lm70->bits_per_word = 8; |
277 | |
278 | lm70llp = pp; |
279 | return; |
280 | |
281 | out_bitbang_stop: |
282 | spi_bitbang_stop(spi: &pp->bitbang); |
283 | out_off_and_release: |
284 | /* power down */ |
285 | parport_write_data(pp->port, 0); |
286 | mdelay(10); |
287 | parport_release(dev: pp->pd); |
288 | out_parport_unreg: |
289 | parport_unregister_device(dev: pd); |
290 | out_free_host: |
291 | spi_controller_put(ctlr: host); |
292 | out_fail: |
293 | pr_info("spi_lm70llp probe fail, status %d\n" , status); |
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(spi: &pp->bitbang); |
305 | |
306 | /* power down */ |
307 | parport_write_data(pp->port, 0); |
308 | |
309 | parport_release(dev: pp->pd); |
310 | parport_unregister_device(dev: pp->pd); |
311 | |
312 | spi_controller_put(ctlr: pp->bitbang.ctlr); |
313 | |
314 | lm70llp = NULL; |
315 | } |
316 | |
317 | static struct parport_driver spi_lm70llp_drv = { |
318 | .name = DRVNAME, |
319 | .match_port = spi_lm70llp_attach, |
320 | .detach = spi_lm70llp_detach, |
321 | .devmodel = true, |
322 | }; |
323 | module_parport_driver(spi_lm70llp_drv); |
324 | |
325 | MODULE_AUTHOR("Kaiwan N Billimoria <kaiwan@designergraphix.com>" ); |
326 | MODULE_DESCRIPTION( |
327 | "Parport adapter for the National Semiconductor LM70 LLP eval board" ); |
328 | MODULE_LICENSE("GPL" ); |
329 | |