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 #include <linux/init.h> 18 #include <linux/module.h> 19 #include <linux/kernel.h> 20 #include <linux/delay.h> 21 #include <linux/device.h> 22 #include <linux/parport.h> 23 #include <linux/sysfs.h> 24 #include <linux/workqueue.h> 25 26 27 #include <linux/spi/spi.h> 28 #include <linux/spi/spi_bitbang.h> 29 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 94 static inline struct spi_lm70llp *spidev_to_pp(struct spi_device *spi) 95 { 96 return spi->controller_data; 97 } 98 99 /*---------------------- LM70 LLP eval board-specific inlines follow */ 100 101 /* NOTE: we don't actually need to reread the output values, since they'll 102 * still be what we wrote before. Plus, going through parport builds in 103 * a ~1ms/operation delay; these SPI transfers could easily be faster. 104 */ 105 106 static inline void deassertCS(struct spi_lm70llp *pp) 107 { 108 u8 data = parport_read_data(pp->port); 109 110 data &= ~0x80; /* pull D7/SI-out low while de-asserted */ 111 parport_write_data(pp->port, data | nCS); 112 } 113 114 static inline void assertCS(struct spi_lm70llp *pp) 115 { 116 u8 data = parport_read_data(pp->port); 117 118 data |= 0x80; /* pull D7/SI-out high so lm70 drives SO-in */ 119 parport_write_data(pp->port, data & ~nCS); 120 } 121 122 static inline void clkHigh(struct spi_lm70llp *pp) 123 { 124 u8 data = parport_read_data(pp->port); 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 parport_write_data(pp->port, data & ~SCLK); 132 } 133 134 /*------------------------- SPI-LM70-specific inlines ----------------------*/ 135 136 static inline void spidelay(unsigned d) 137 { 138 udelay(d); 139 } 140 141 static inline void setsck(struct spi_device *s, int is_on) 142 { 143 struct spi_lm70llp *pp = spidev_to_pp(s); 144 145 if (is_on) 146 clkHigh(pp); 147 else 148 clkLow(pp); 149 } 150 151 static inline void setmosi(struct spi_device *s, int is_on) 152 { 153 /* FIXME update D7 ... this way we can put the chip 154 * into shutdown mode and read the manufacturer ID, 155 * but we can't put it back into operational mode. 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 */ 166 static 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" 174 175 static 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 */ 188 static 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 } 192 193 static 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 /* 219 * SPI and bitbang hookup. 220 */ 221 pp->bitbang.master = master; 222 pp->bitbang.chipselect = lm70_chipselect; 223 pp->bitbang.txrx_word[SPI_MODE_0] = lm70_txrx; 224 pp->bitbang.flags = SPI_3WIRE; 225 226 /* 227 * Parport hookup 228 */ 229 pp->port = p; 230 pd = parport_register_device(p, DRVNAME, 231 NULL, NULL, NULL, 232 PARPORT_FLAG_EXCL, pp); 233 if (!pd) { 234 status = -ENOMEM; 235 goto out_free_master; 236 } 237 pp->pd = pd; 238 239 status = parport_claim(pd); 240 if (status < 0) 241 goto out_parport_unreg; 242 243 /* 244 * Start SPI ... 245 */ 246 status = spi_bitbang_start(&pp->bitbang); 247 if (status < 0) { 248 printk(KERN_WARNING 249 "%s: spi_bitbang_start failed with status %d\n", 250 DRVNAME, status); 251 goto out_off_and_release; 252 } 253 254 /* 255 * The modalias name MUST match the device_driver name 256 * for the bus glue code to match and subsequently bind them. 257 * We are binding to the generic drivers/hwmon/lm70.c device 258 * driver. 259 */ 260 strcpy(pp->info.modalias, "lm70"); 261 pp->info.max_speed_hz = 6 * 1000 * 1000; 262 pp->info.chip_select = 0; 263 pp->info.mode = SPI_3WIRE | SPI_MODE_0; 264 265 /* power up the chip, and let the LM70 control SI/SO */ 266 parport_write_data(pp->port, lm70_INIT); 267 268 /* Enable access to our primary data structure via 269 * the board info's (void *)controller_data. 270 */ 271 pp->info.controller_data = pp; 272 pp->spidev_lm70 = spi_new_device(pp->bitbang.master, &pp->info); 273 if (pp->spidev_lm70) 274 dev_dbg(&pp->spidev_lm70->dev, "spidev_lm70 at %s\n", 275 dev_name(&pp->spidev_lm70->dev)); 276 else { 277 printk(KERN_WARNING "%s: spi_new_device failed\n", DRVNAME); 278 status = -ENODEV; 279 goto out_bitbang_stop; 280 } 281 pp->spidev_lm70->bits_per_word = 8; 282 283 lm70llp = pp; 284 return; 285 286 out_bitbang_stop: 287 spi_bitbang_stop(&pp->bitbang); 288 out_off_and_release: 289 /* power down */ 290 parport_write_data(pp->port, 0); 291 mdelay(10); 292 parport_release(pp->pd); 293 out_parport_unreg: 294 parport_unregister_device(pd); 295 out_free_master: 296 (void) spi_master_put(master); 297 out_fail: 298 pr_info("%s: spi_lm70llp probe fail, status %d\n", DRVNAME, status); 299 } 300 301 static void spi_lm70llp_detach(struct parport *p) 302 { 303 struct spi_lm70llp *pp; 304 305 if (!lm70llp || lm70llp->port != p) 306 return; 307 308 pp = lm70llp; 309 spi_bitbang_stop(&pp->bitbang); 310 311 /* power down */ 312 parport_write_data(pp->port, 0); 313 314 parport_release(pp->pd); 315 parport_unregister_device(pp->pd); 316 317 (void) spi_master_put(pp->bitbang.master); 318 319 lm70llp = NULL; 320 } 321 322 323 static struct parport_driver spi_lm70llp_drv = { 324 .name = DRVNAME, 325 .attach = spi_lm70llp_attach, 326 .detach = spi_lm70llp_detach, 327 }; 328 329 static int __init init_spi_lm70llp(void) 330 { 331 return parport_register_driver(&spi_lm70llp_drv); 332 } 333 module_init(init_spi_lm70llp); 334 335 static void __exit cleanup_spi_lm70llp(void) 336 { 337 parport_unregister_driver(&spi_lm70llp_drv); 338 } 339 module_exit(cleanup_spi_lm70llp); 340 341 MODULE_AUTHOR("Kaiwan N Billimoria <kaiwan@designergraphix.com>"); 342 MODULE_DESCRIPTION( 343 "Parport adapter for the National Semiconductor LM70 LLP eval board"); 344 MODULE_LICENSE("GPL"); 345