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 * 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 * Datasheet and Schematic: 44 * The LM70 is a temperature sensor chip from National Semiconductor; its 45 * datasheet is available at http://www.national.com/pf/LM/LM70.html 46 * The schematic for this particular board (the LM70EVAL-LLP) is 47 * available (on page 4) here: 48 * http://www.national.com/appinfo/tempsensors/files/LM70LLPEVALmanual.pdf 49 * 50 * Also see Documentation/spi/spi-lm70llp. The SPI<->parport code here is 51 * (heavily) based on spi-butterfly by David Brownell. 52 * 53 * The LM70 LLP connects to the PC parallel port in the following manner: 54 * 55 * Parallel LM70 LLP 56 * Port Direction JP2 Header 57 * ----------- --------- ------------ 58 * D0 2 - - 59 * D1 3 --> V+ 5 60 * D2 4 --> V+ 5 61 * D3 5 --> V+ 5 62 * D4 6 --> V+ 5 63 * D5 7 --> nCS 8 64 * D6 8 --> SCLK 3 65 * D7 9 --> SI/O 5 66 * GND 25 - GND 7 67 * Select 13 <-- SI/O 1 68 * 69 * Note that parport pin 13 actually gets inverted by the transistor 70 * arrangement which lets either the parport or the LM70 drive the 71 * SI/SO signal (see the schematic for details). 72 */ 73 74 #define DRVNAME "spi-lm70llp" 75 76 #define lm70_INIT 0xBE 77 #define SIO 0x10 78 #define nCS 0x20 79 #define SCLK 0x40 80 81 /*-------------------------------------------------------------------------*/ 82 83 struct spi_lm70llp { 84 struct spi_bitbang bitbang; 85 struct parport *port; 86 struct pardevice *pd; 87 struct spi_device *spidev_lm70; 88 struct spi_board_info info; 89 //struct device *dev; 90 }; 91 92 /* REVISIT : ugly global ; provides "exclusive open" facility */ 93 static struct spi_lm70llp *lm70llp; 94 95 96 /*-------------------------------------------------------------------*/ 97 98 static inline struct spi_lm70llp *spidev_to_pp(struct spi_device *spi) 99 { 100 return spi->controller_data; 101 } 102 103 /*---------------------- LM70 LLP eval board-specific inlines follow */ 104 105 /* NOTE: we don't actually need to reread the output values, since they'll 106 * still be what we wrote before. Plus, going through parport builds in 107 * a ~1ms/operation delay; these SPI transfers could easily be faster. 108 */ 109 110 static inline void deassertCS(struct spi_lm70llp *pp) 111 { 112 u8 data = parport_read_data(pp->port); 113 114 data &= ~0x80; /* pull D7/SI-out low while de-asserted */ 115 parport_write_data(pp->port, data | nCS); 116 } 117 118 static inline void assertCS(struct spi_lm70llp *pp) 119 { 120 u8 data = parport_read_data(pp->port); 121 122 data |= 0x80; /* pull D7/SI-out high so lm70 drives SO-in */ 123 parport_write_data(pp->port, data & ~nCS); 124 } 125 126 static inline void clkHigh(struct spi_lm70llp *pp) 127 { 128 u8 data = parport_read_data(pp->port); 129 parport_write_data(pp->port, data | SCLK); 130 } 131 132 static inline void clkLow(struct spi_lm70llp *pp) 133 { 134 u8 data = parport_read_data(pp->port); 135 parport_write_data(pp->port, data & ~SCLK); 136 } 137 138 /*------------------------- SPI-LM70-specific inlines ----------------------*/ 139 140 static inline void spidelay(unsigned d) 141 { 142 udelay(d); 143 } 144 145 static inline void setsck(struct spi_device *s, int is_on) 146 { 147 struct spi_lm70llp *pp = spidev_to_pp(s); 148 149 if (is_on) 150 clkHigh(pp); 151 else 152 clkLow(pp); 153 } 154 155 static inline void setmosi(struct spi_device *s, int is_on) 156 { 157 /* FIXME update D7 ... this way we can put the chip 158 * into shutdown mode and read the manufacturer ID, 159 * but we can't put it back into operational mode. 160 */ 161 } 162 163 /* 164 * getmiso: 165 * Why do we return 0 when the SIO line is high and vice-versa? 166 * The fact is, the lm70 eval board from NS (which this driver drives), 167 * is wired in just such a way : when the lm70's SIO goes high, a transistor 168 * switches it to low reflecting this on the parport (pin 13), and vice-versa. 169 */ 170 static inline int getmiso(struct spi_device *s) 171 { 172 struct spi_lm70llp *pp = spidev_to_pp(s); 173 return ((SIO == (parport_read_status(pp->port) & SIO)) ? 0 : 1 ); 174 } 175 /*--------------------------------------------------------------------*/ 176 177 #include "spi-bitbang-txrx.h" 178 179 static void lm70_chipselect(struct spi_device *spi, int value) 180 { 181 struct spi_lm70llp *pp = spidev_to_pp(spi); 182 183 if (value) 184 assertCS(pp); 185 else 186 deassertCS(pp); 187 } 188 189 /* 190 * Our actual bitbanger routine. 191 */ 192 static u32 lm70_txrx(struct spi_device *spi, unsigned nsecs, u32 word, u8 bits) 193 { 194 return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, 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; 203 204 if (lm70llp) { 205 printk(KERN_WARNING 206 "%s: spi_lm70llp instance already loaded. Aborting.\n", 207 DRVNAME); 208 return; 209 } 210 211 /* TODO: this just _assumes_ a lm70 is there ... no probe; 212 * the lm70 driver could verify it, reading the manf ID. 213 */ 214 215 master = spi_alloc_master(p->physport->dev, sizeof *pp); 216 if (!master) { 217 status = -ENOMEM; 218 goto out_fail; 219 } 220 pp = spi_master_get_devdata(master); 221 222 /* 223 * SPI and bitbang hookup. 224 */ 225 pp->bitbang.master = spi_master_get(master); 226 pp->bitbang.chipselect = lm70_chipselect; 227 pp->bitbang.txrx_word[SPI_MODE_0] = lm70_txrx; 228 pp->bitbang.flags = SPI_3WIRE; 229 230 /* 231 * Parport hookup 232 */ 233 pp->port = p; 234 pd = parport_register_device(p, DRVNAME, 235 NULL, NULL, NULL, 236 PARPORT_FLAG_EXCL, pp); 237 if (!pd) { 238 status = -ENOMEM; 239 goto out_free_master; 240 } 241 pp->pd = pd; 242 243 status = parport_claim(pd); 244 if (status < 0) 245 goto out_parport_unreg; 246 247 /* 248 * Start SPI ... 249 */ 250 status = spi_bitbang_start(&pp->bitbang); 251 if (status < 0) { 252 printk(KERN_WARNING 253 "%s: spi_bitbang_start failed with status %d\n", 254 DRVNAME, 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 printk(KERN_WARNING "%s: spi_new_device failed\n", DRVNAME); 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 (void) spi_master_put(master); 301 out_fail: 302 pr_info("%s: spi_lm70llp probe fail, status %d\n", DRVNAME, 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 (void) spi_master_put(pp->bitbang.master); 322 323 lm70llp = NULL; 324 } 325 326 327 static struct parport_driver spi_lm70llp_drv = { 328 .name = DRVNAME, 329 .attach = spi_lm70llp_attach, 330 .detach = spi_lm70llp_detach, 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