1/* 2 * spi_lm70llp.c - 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 83struct 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 */ 93static struct spi_lm70llp *lm70llp; 94 95 96/*-------------------------------------------------------------------*/ 97 98static 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 110static 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 118static 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 126static 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 132static 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 140static inline void spidelay(unsigned d) 141{ 142 udelay(d); 143} 144 145static 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 155static inline void setmosi(struct spi_device *s, int is_on) 156{ 157} 158 159/* 160 * getmiso: 161 * Why do we return 0 when the SIO line is high and vice-versa? 162 * The fact is, the lm70 eval board from NS (which this driver drives), 163 * is wired in just such a way : when the lm70's SIO goes high, a transistor 164 * switches it to low reflecting this on the parport (pin 13), and vice-versa. 165 */ 166static inline int getmiso(struct spi_device *s) 167{ 168 struct spi_lm70llp *pp = spidev_to_pp(s); 169 return ((SIO == (parport_read_status(pp->port) & SIO)) ? 0 : 1 ); 170} 171/*--------------------------------------------------------------------*/ 172 173#include "spi_bitbang_txrx.h" 174 175static void lm70_chipselect(struct spi_device *spi, int value) 176{ 177 struct spi_lm70llp *pp = spidev_to_pp(spi); 178 179 if (value) 180 assertCS(pp); 181 else 182 deassertCS(pp); 183} 184 185/* 186 * Our actual bitbanger routine. 187 */ 188static u32 lm70_txrx(struct spi_device *spi, unsigned nsecs, u32 word, u8 bits) 189{ 190 return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits); 191} 192 193static void spi_lm70llp_attach(struct parport *p) 194{ 195 struct pardevice *pd; 196 struct spi_lm70llp *pp; 197 struct spi_master *master; 198 int status; 199 200 if (lm70llp) { 201 printk(KERN_WARNING 202 "%s: spi_lm70llp instance already loaded. Aborting.\n", 203 DRVNAME); 204 return; 205 } 206 207 /* TODO: this just _assumes_ a lm70 is there ... no probe; 208 * the lm70 driver could verify it, reading the manf ID. 209 */ 210 211 master = spi_alloc_master(p->physport->dev, sizeof *pp); 212 if (!master) { 213 status = -ENOMEM; 214 goto out_fail; 215 } 216 pp = spi_master_get_devdata(master); 217 218 master->bus_num = -1; /* dynamic alloc of a bus number */ 219 master->num_chipselect = 1; 220 221 /* 222 * SPI and bitbang hookup. 223 */ 224 pp->bitbang.master = spi_master_get(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 pd = parport_register_device(p, DRVNAME, 234 NULL, NULL, NULL, 235 PARPORT_FLAG_EXCL, pp); 236 if (!pd) { 237 status = -ENOMEM; 238 goto out_free_master; 239 } 240 pp->pd = pd; 241 242 status = parport_claim(pd); 243 if (status < 0) 244 goto out_parport_unreg; 245 246 /* 247 * Start SPI ... 248 */ 249 status = spi_bitbang_start(&pp->bitbang); 250 if (status < 0) { 251 printk(KERN_WARNING 252 "%s: spi_bitbang_start failed with status %d\n", 253 DRVNAME, status); 254 goto out_off_and_release; 255 } 256 257 /* 258 * The modalias name MUST match the device_driver name 259 * for the bus glue code to match and subsequently bind them. 260 * We are binding to the generic drivers/hwmon/lm70.c device 261 * driver. 262 */ 263 strcpy(pp->info.modalias, "lm70"); 264 pp->info.max_speed_hz = 6 * 1000 * 1000; 265 pp->info.chip_select = 0; 266 pp->info.mode = SPI_3WIRE | SPI_MODE_0; 267 268 /* power up the chip, and let the LM70 control SI/SO */ 269 parport_write_data(pp->port, lm70_INIT); 270 271 /* Enable access to our primary data structure via 272 * the board info's (void *)controller_data. 273 */ 274 pp->info.controller_data = pp; 275 pp->spidev_lm70 = spi_new_device(pp->bitbang.master, &pp->info); 276 if (pp->spidev_lm70) 277 dev_dbg(&pp->spidev_lm70->dev, "spidev_lm70 at %s\n", 278 dev_name(&pp->spidev_lm70->dev)); 279 else { 280 printk(KERN_WARNING "%s: spi_new_device failed\n", DRVNAME); 281 status = -ENODEV; 282 goto out_bitbang_stop; 283 } 284 pp->spidev_lm70->bits_per_word = 8; 285 286 lm70llp = pp; 287 return; 288 289out_bitbang_stop: 290 spi_bitbang_stop(&pp->bitbang); 291out_off_and_release: 292 /* power down */ 293 parport_write_data(pp->port, 0); 294 mdelay(10); 295 parport_release(pp->pd); 296out_parport_unreg: 297 parport_unregister_device(pd); 298out_free_master: 299 (void) spi_master_put(master); 300out_fail: 301 pr_info("%s: spi_lm70llp probe fail, status %d\n", DRVNAME, status); 302} 303 304static void spi_lm70llp_detach(struct parport *p) 305{ 306 struct spi_lm70llp *pp; 307 308 if (!lm70llp || lm70llp->port != p) 309 return; 310 311 pp = lm70llp; 312 spi_bitbang_stop(&pp->bitbang); 313 314 /* power down */ 315 parport_write_data(pp->port, 0); 316 317 parport_release(pp->pd); 318 parport_unregister_device(pp->pd); 319 320 (void) spi_master_put(pp->bitbang.master); 321 322 lm70llp = NULL; 323} 324 325 326static struct parport_driver spi_lm70llp_drv = { 327 .name = DRVNAME, 328 .attach = spi_lm70llp_attach, 329 .detach = spi_lm70llp_detach, 330}; 331 332static int __init init_spi_lm70llp(void) 333{ 334 return parport_register_driver(&spi_lm70llp_drv); 335} 336module_init(init_spi_lm70llp); 337 338static void __exit cleanup_spi_lm70llp(void) 339{ 340 parport_unregister_driver(&spi_lm70llp_drv); 341} 342module_exit(cleanup_spi_lm70llp); 343 344MODULE_AUTHOR("Kaiwan N Billimoria <kaiwan@designergraphix.com>"); 345MODULE_DESCRIPTION( 346 "Parport adapter for the National Semiconductor LM70 LLP eval board"); 347MODULE_LICENSE("GPL"); 348