1 /* 2 * 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 17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 18 19 #include <linux/init.h> 20 #include <linux/module.h> 21 #include <linux/kernel.h> 22 #include <linux/delay.h> 23 #include <linux/device.h> 24 #include <linux/parport.h> 25 #include <linux/sysfs.h> 26 #include <linux/workqueue.h> 27 28 #include <linux/spi/spi.h> 29 #include <linux/spi/spi_bitbang.h> 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 * 39 * Datasheet and Schematic: 40 * The LM70 is a temperature sensor chip from National Semiconductor; its 41 * datasheet is available at http://www.national.com/pf/LM/LM70.html 42 * 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 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 (see the schematic for details). 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 79 struct 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 device *dev; 86 }; 87 88 /* REVISIT : ugly global ; provides "exclusive open" facility */ 89 static struct spi_lm70llp *lm70llp; 90 91 /*-------------------------------------------------------------------*/ 92 93 static inline struct spi_lm70llp *spidev_to_pp(struct spi_device *spi) 94 { 95 return spi->controller_data; 96 } 97 98 /*---------------------- LM70 LLP eval board-specific inlines follow */ 99 100 /* NOTE: we don't actually need to reread the output values, since they'll 101 * still be what we wrote before. Plus, going through parport builds in 102 * a ~1ms/operation delay; these SPI transfers could easily be faster. 103 */ 104 105 static inline void deassertCS(struct spi_lm70llp *pp) 106 { 107 u8 data = parport_read_data(pp->port); 108 109 data &= ~0x80; /* pull D7/SI-out low while de-asserted */ 110 parport_write_data(pp->port, data | nCS); 111 } 112 113 static inline void assertCS(struct spi_lm70llp *pp) 114 { 115 u8 data = parport_read_data(pp->port); 116 117 data |= 0x80; /* pull D7/SI-out high so lm70 drives SO-in */ 118 parport_write_data(pp->port, data & ~nCS); 119 } 120 121 static inline void clkHigh(struct spi_lm70llp *pp) 122 { 123 u8 data = parport_read_data(pp->port); 124 125 parport_write_data(pp->port, data | SCLK); 126 } 127 128 static inline void clkLow(struct spi_lm70llp *pp) 129 { 130 u8 data = parport_read_data(pp->port); 131 132 parport_write_data(pp->port, data & ~SCLK); 133 } 134 135 /*------------------------- SPI-LM70-specific inlines ----------------------*/ 136 137 static inline void spidelay(unsigned d) 138 { 139 udelay(d); 140 } 141 142 static inline void setsck(struct spi_device *s, int is_on) 143 { 144 struct spi_lm70llp *pp = spidev_to_pp(s); 145 146 if (is_on) 147 clkHigh(pp); 148 else 149 clkLow(pp); 150 } 151 152 static inline void setmosi(struct spi_device *s, int is_on) 153 { 154 /* FIXME update D7 ... this way we can put the chip 155 * into shutdown mode and read the manufacturer ID, 156 * but we can't put it back into operational mode. 157 */ 158 } 159 160 /* 161 * getmiso: 162 * Why do we return 0 when the SIO line is high and vice-versa? 163 * The fact is, the lm70 eval board from NS (which this driver drives), 164 * is wired in just such a way : when the lm70's SIO goes high, a transistor 165 * switches it to low reflecting this on the parport (pin 13), and vice-versa. 166 */ 167 static inline int getmiso(struct spi_device *s) 168 { 169 struct spi_lm70llp *pp = spidev_to_pp(s); 170 171 return ((SIO == (parport_read_status(pp->port) & SIO)) ? 0 : 1); 172 } 173 174 /*--------------------------------------------------------------------*/ 175 176 #include "spi-bitbang-txrx.h" 177 178 static void lm70_chipselect(struct spi_device *spi, int value) 179 { 180 struct spi_lm70llp *pp = spidev_to_pp(spi); 181 182 if (value) 183 assertCS(pp); 184 else 185 deassertCS(pp); 186 } 187 188 /* 189 * Our actual bitbanger routine. 190 */ 191 static u32 lm70_txrx(struct spi_device *spi, unsigned nsecs, u32 word, u8 bits, 192 unsigned flags) 193 { 194 return bitbang_txrx_be_cpha0(spi, nsecs, 0, flags, word, bits); 195 } 196 197 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 struct pardev_cb lm70llp_cb; 204 205 if (lm70llp) { 206 pr_warn("spi_lm70llp instance already loaded. Aborting.\n"); 207 return; 208 } 209 210 /* TODO: this just _assumes_ a lm70 is there ... no probe; 211 * the lm70 driver could verify it, reading the manf ID. 212 */ 213 214 master = spi_alloc_master(p->physport->dev, sizeof *pp); 215 if (!master) { 216 status = -ENOMEM; 217 goto out_fail; 218 } 219 pp = spi_master_get_devdata(master); 220 221 /* 222 * SPI and bitbang hookup. 223 */ 224 pp->bitbang.master = master; 225 pp->bitbang.chipselect = lm70_chipselect; 226 pp->bitbang.txrx_word[SPI_MODE_0] = lm70_txrx; 227 pp->bitbang.flags = SPI_3WIRE; 228 229 /* 230 * Parport hookup 231 */ 232 pp->port = p; 233 memset(&lm70llp_cb, 0, sizeof(lm70llp_cb)); 234 lm70llp_cb.private = pp; 235 lm70llp_cb.flags = PARPORT_FLAG_EXCL; 236 pd = parport_register_dev_model(p, DRVNAME, &lm70llp_cb, 0); 237 238 if (!pd) { 239 status = -ENOMEM; 240 goto out_free_master; 241 } 242 pp->pd = pd; 243 244 status = parport_claim(pd); 245 if (status < 0) 246 goto out_parport_unreg; 247 248 /* 249 * Start SPI ... 250 */ 251 status = spi_bitbang_start(&pp->bitbang); 252 if (status < 0) { 253 dev_warn(&pd->dev, "spi_bitbang_start failed with status %d\n", 254 status); 255 goto out_off_and_release; 256 } 257 258 /* 259 * The modalias name MUST match the device_driver name 260 * for the bus glue code to match and subsequently bind them. 261 * We are binding to the generic drivers/hwmon/lm70.c device 262 * driver. 263 */ 264 strcpy(pp->info.modalias, "lm70"); 265 pp->info.max_speed_hz = 6 * 1000 * 1000; 266 pp->info.chip_select = 0; 267 pp->info.mode = SPI_3WIRE | SPI_MODE_0; 268 269 /* power up the chip, and let the LM70 control SI/SO */ 270 parport_write_data(pp->port, lm70_INIT); 271 272 /* Enable access to our primary data structure via 273 * the board info's (void *)controller_data. 274 */ 275 pp->info.controller_data = pp; 276 pp->spidev_lm70 = spi_new_device(pp->bitbang.master, &pp->info); 277 if (pp->spidev_lm70) 278 dev_dbg(&pp->spidev_lm70->dev, "spidev_lm70 at %s\n", 279 dev_name(&pp->spidev_lm70->dev)); 280 else { 281 dev_warn(&pd->dev, "spi_new_device failed\n"); 282 status = -ENODEV; 283 goto out_bitbang_stop; 284 } 285 pp->spidev_lm70->bits_per_word = 8; 286 287 lm70llp = pp; 288 return; 289 290 out_bitbang_stop: 291 spi_bitbang_stop(&pp->bitbang); 292 out_off_and_release: 293 /* power down */ 294 parport_write_data(pp->port, 0); 295 mdelay(10); 296 parport_release(pp->pd); 297 out_parport_unreg: 298 parport_unregister_device(pd); 299 out_free_master: 300 spi_master_put(master); 301 out_fail: 302 pr_info("spi_lm70llp probe fail, status %d\n", status); 303 } 304 305 static void spi_lm70llp_detach(struct parport *p) 306 { 307 struct spi_lm70llp *pp; 308 309 if (!lm70llp || lm70llp->port != p) 310 return; 311 312 pp = lm70llp; 313 spi_bitbang_stop(&pp->bitbang); 314 315 /* power down */ 316 parport_write_data(pp->port, 0); 317 318 parport_release(pp->pd); 319 parport_unregister_device(pp->pd); 320 321 spi_master_put(pp->bitbang.master); 322 323 lm70llp = NULL; 324 } 325 326 static struct parport_driver spi_lm70llp_drv = { 327 .name = DRVNAME, 328 .match_port = spi_lm70llp_attach, 329 .detach = spi_lm70llp_detach, 330 .devmodel = true, 331 }; 332 333 static int __init init_spi_lm70llp(void) 334 { 335 return parport_register_driver(&spi_lm70llp_drv); 336 } 337 module_init(init_spi_lm70llp); 338 339 static void __exit cleanup_spi_lm70llp(void) 340 { 341 parport_unregister_driver(&spi_lm70llp_drv); 342 } 343 module_exit(cleanup_spi_lm70llp); 344 345 MODULE_AUTHOR("Kaiwan N Billimoria <kaiwan@designergraphix.com>"); 346 MODULE_DESCRIPTION( 347 "Parport adapter for the National Semiconductor LM70 LLP eval board"); 348 MODULE_LICENSE("GPL"); 349