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drivers/w1/w1_io.c
11.4 KB
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/* |
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* w1_io.c |
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* |
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* Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net> |
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* |
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* * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #include <asm/io.h> #include <linux/delay.h> #include <linux/moduleparam.h> |
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#include <linux/module.h> |
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#include "w1.h" #include "w1_log.h" |
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static int w1_delay_parm = 1; |
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module_param_named(delay_coef, w1_delay_parm, int, 0); static u8 w1_crc8_table[] = { 0, 94, 188, 226, 97, 63, 221, 131, 194, 156, 126, 32, 163, 253, 31, 65, 157, 195, 33, 127, 252, 162, 64, 30, 95, 1, 227, 189, 62, 96, 130, 220, 35, 125, 159, 193, 66, 28, 254, 160, 225, 191, 93, 3, 128, 222, 60, 98, 190, 224, 2, 92, 223, 129, 99, 61, 124, 34, 192, 158, 29, 67, 161, 255, 70, 24, 250, 164, 39, 121, 155, 197, 132, 218, 56, 102, 229, 187, 89, 7, 219, 133, 103, 57, 186, 228, 6, 88, 25, 71, 165, 251, 120, 38, 196, 154, 101, 59, 217, 135, 4, 90, 184, 230, 167, 249, 27, 69, 198, 152, 122, 36, 248, 166, 68, 26, 153, 199, 37, 123, 58, 100, 134, 216, 91, 5, 231, 185, 140, 210, 48, 110, 237, 179, 81, 15, 78, 16, 242, 172, 47, 113, 147, 205, 17, 79, 173, 243, 112, 46, 204, 146, 211, 141, 111, 49, 178, 236, 14, 80, 175, 241, 19, 77, 206, 144, 114, 44, 109, 51, 209, 143, 12, 82, 176, 238, 50, 108, 142, 208, 83, 13, 239, 177, 240, 174, 76, 18, 145, 207, 45, 115, 202, 148, 118, 40, 171, 245, 23, 73, 8, 86, 180, 234, 105, 55, 213, 139, 87, 9, 235, 181, 54, 104, 138, 212, 149, 203, 41, 119, 244, 170, 72, 22, 233, 183, 85, 11, 136, 214, 52, 106, 43, 117, 151, 201, 74, 20, 246, 168, 116, 42, 200, 150, 21, 75, 169, 247, 182, 232, 10, 84, 215, 137, 107, 53 }; |
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static void w1_delay(unsigned long tm) |
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{ udelay(tm * w1_delay_parm); } |
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static void w1_write_bit(struct w1_master *dev, int bit); static u8 w1_read_bit(struct w1_master *dev); /** * Generates a write-0 or write-1 cycle and samples the level. */ |
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static u8 w1_touch_bit(struct w1_master *dev, int bit) |
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{ if (dev->bus_master->touch_bit) return dev->bus_master->touch_bit(dev->bus_master->data, bit); |
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else if (bit) |
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return w1_read_bit(dev); |
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else { w1_write_bit(dev, 0); |
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return 0; |
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} |
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} |
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/** * Generates a write-0 or write-1 cycle. * Only call if dev->bus_master->touch_bit is NULL */ static void w1_write_bit(struct w1_master *dev, int bit) |
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{ if (bit) { dev->bus_master->write_bit(dev->bus_master->data, 0); w1_delay(6); dev->bus_master->write_bit(dev->bus_master->data, 1); w1_delay(64); } else { dev->bus_master->write_bit(dev->bus_master->data, 0); w1_delay(60); dev->bus_master->write_bit(dev->bus_master->data, 1); w1_delay(10); } } |
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/** |
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* Pre-write operation, currently only supporting strong pullups. * Program the hardware for a strong pullup, if one has been requested and * the hardware supports it. * * @param dev the master device */ static void w1_pre_write(struct w1_master *dev) { if (dev->pullup_duration && dev->enable_pullup && dev->bus_master->set_pullup) { dev->bus_master->set_pullup(dev->bus_master->data, dev->pullup_duration); } } /** * Post-write operation, currently only supporting strong pullups. * If a strong pullup was requested, clear it if the hardware supports * them, or execute the delay otherwise, in either case clear the request. * * @param dev the master device */ static void w1_post_write(struct w1_master *dev) { if (dev->pullup_duration) { if (dev->enable_pullup && dev->bus_master->set_pullup) dev->bus_master->set_pullup(dev->bus_master->data, 0); else msleep(dev->pullup_duration); dev->pullup_duration = 0; } } /** |
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* Writes 8 bits. * * @param dev the master device * @param byte the byte to write */ |
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void w1_write_8(struct w1_master *dev, u8 byte) { int i; |
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if (dev->bus_master->write_byte) { w1_pre_write(dev); |
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dev->bus_master->write_byte(dev->bus_master->data, byte); |
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} |
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else |
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for (i = 0; i < 8; ++i) { if (i == 7) w1_pre_write(dev); |
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w1_touch_bit(dev, (byte >> i) & 0x1); |
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} w1_post_write(dev); |
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} |
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EXPORT_SYMBOL_GPL(w1_write_8); |
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|
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/** * Generates a write-1 cycle and samples the level. * Only call if dev->bus_master->touch_bit is NULL */ static u8 w1_read_bit(struct w1_master *dev) |
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{ int result; |
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unsigned long flags; |
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|
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/* sample timing is critical here */ local_irq_save(flags); |
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dev->bus_master->write_bit(dev->bus_master->data, 0); w1_delay(6); dev->bus_master->write_bit(dev->bus_master->data, 1); w1_delay(9); result = dev->bus_master->read_bit(dev->bus_master->data); |
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local_irq_restore(flags); |
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w1_delay(55); return result & 0x1; } |
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/** |
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* Does a triplet - used for searching ROM addresses. * Return bits: * bit 0 = id_bit * bit 1 = comp_bit * bit 2 = dir_taken * If both bits 0 & 1 are set, the search should be restarted. * * @param dev the master device * @param bdir the bit to write if both id_bit and comp_bit are 0 * @return bit fields - see above */ u8 w1_triplet(struct w1_master *dev, int bdir) { |
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if (dev->bus_master->triplet) return dev->bus_master->triplet(dev->bus_master->data, bdir); |
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else { u8 id_bit = w1_touch_bit(dev, 1); u8 comp_bit = w1_touch_bit(dev, 1); u8 retval; |
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if (id_bit && comp_bit) return 0x03; /* error */ |
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if (!id_bit && !comp_bit) { |
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/* Both bits are valid, take the direction given */ retval = bdir ? 0x04 : 0; } else { /* Only one bit is valid, take that direction */ bdir = id_bit; retval = id_bit ? 0x05 : 0x02; } |
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if (dev->bus_master->touch_bit) |
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w1_touch_bit(dev, bdir); else w1_write_bit(dev, bdir); |
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return retval; |
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} } /** |
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* Reads 8 bits. * * @param dev the master device * @return the byte read */ |
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u8 w1_read_8(struct w1_master *dev) |
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{ int i; u8 res = 0; if (dev->bus_master->read_byte) res = dev->bus_master->read_byte(dev->bus_master->data); else for (i = 0; i < 8; ++i) |
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res |= (w1_touch_bit(dev,1) << i); |
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return res; } |
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EXPORT_SYMBOL_GPL(w1_read_8); |
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/** * Writes a series of bytes. * * @param dev the master device * @param buf pointer to the data to write * @param len the number of bytes to write |
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*/ void w1_write_block(struct w1_master *dev, const u8 *buf, int len) |
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{ int i; |
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if (dev->bus_master->write_block) { w1_pre_write(dev); |
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dev->bus_master->write_block(dev->bus_master->data, buf, len); |
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} |
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else for (i = 0; i < len; ++i) |
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w1_write_8(dev, buf[i]); /* calls w1_pre_write */ w1_post_write(dev); |
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} |
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EXPORT_SYMBOL_GPL(w1_write_block); |
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|
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/** |
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* Touches a series of bytes. * * @param dev the master device * @param buf pointer to the data to write * @param len the number of bytes to write */ void w1_touch_block(struct w1_master *dev, u8 *buf, int len) { int i, j; u8 tmp; for (i = 0; i < len; ++i) { tmp = 0; for (j = 0; j < 8; ++j) { if (j == 7) w1_pre_write(dev); tmp |= w1_touch_bit(dev, (buf[i] >> j) & 0x1) << j; } buf[i] = tmp; } } EXPORT_SYMBOL_GPL(w1_touch_block); /** |
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* Reads a series of bytes. * * @param dev the master device * @param buf pointer to the buffer to fill * @param len the number of bytes to read * @return the number of bytes read */ |
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u8 w1_read_block(struct w1_master *dev, u8 *buf, int len) { int i; u8 ret; if (dev->bus_master->read_block) ret = dev->bus_master->read_block(dev->bus_master->data, buf, len); else { for (i = 0; i < len; ++i) buf[i] = w1_read_8(dev); ret = len; } return ret; } |
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EXPORT_SYMBOL_GPL(w1_read_block); |
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/** * Issues a reset bus sequence. * * @param dev The bus master pointer * @return 0=Device present, 1=No device present or error */ |
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int w1_reset_bus(struct w1_master *dev) { |
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int result; |
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if (dev->bus_master->reset_bus) result = dev->bus_master->reset_bus(dev->bus_master->data) & 0x1; else { dev->bus_master->write_bit(dev->bus_master->data, 0); |
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/* minimum 480, max ? us * be nice and sleep, except 18b20 spec lists 960us maximum, * so until we can sleep with microsecond accuracy, spin. * Feel free to come up with some other way to give up the * cpu for such a short amount of time AND get it back in * the maximum amount of time. */ |
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w1_delay(480); dev->bus_master->write_bit(dev->bus_master->data, 1); w1_delay(70); result = dev->bus_master->read_bit(dev->bus_master->data) & 0x1; |
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/* minmum 70 (above) + 410 = 480 us * There aren't any timing requirements between a reset and * the following transactions. Sleeping is safe here. */ /* w1_delay(410); min required time */ msleep(1); |
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} return result; } |
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EXPORT_SYMBOL_GPL(w1_reset_bus); |
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u8 w1_calc_crc8(u8 * data, int len) { u8 crc = 0; while (len--) crc = w1_crc8_table[crc ^ *data++]; return crc; } |
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EXPORT_SYMBOL_GPL(w1_calc_crc8); |
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|
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void w1_search_devices(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb) |
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{ dev->attempts++; if (dev->bus_master->search) |
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dev->bus_master->search(dev->bus_master->data, dev, search_type, cb); |
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else |
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w1_search(dev, search_type, cb); |
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} |
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/** * Resets the bus and then selects the slave by sending either a skip rom * or a rom match. * The w1 master lock must be held. * * @param sl the slave to select * @return 0=success, anything else=error */ int w1_reset_select_slave(struct w1_slave *sl) { if (w1_reset_bus(sl->master)) return -1; if (sl->master->slave_count == 1) w1_write_8(sl->master, W1_SKIP_ROM); else { u8 match[9] = {W1_MATCH_ROM, }; |
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u64 rn = le64_to_cpu(*((u64*)&sl->reg_num)); memcpy(&match[1], &rn, 8); |
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w1_write_block(sl->master, match, 9); } return 0; } |
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EXPORT_SYMBOL_GPL(w1_reset_select_slave); |
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/** |
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* When the workflow with a slave amongst many requires several * successive commands a reset between each, this function is similar * to doing a reset then a match ROM for the last matched ROM. The * advantage being that the matched ROM step is skipped in favor of the * resume command. The slave must support the command of course. * * If the bus has only one slave, traditionnaly the match ROM is skipped * and a "SKIP ROM" is done for efficiency. On multi-slave busses, this * doesn't work of course, but the resume command is the next best thing. * * The w1 master lock must be held. * * @param dev the master device */ int w1_reset_resume_command(struct w1_master *dev) { if (w1_reset_bus(dev)) return -1; /* This will make only the last matched slave perform a skip ROM. */ w1_write_8(dev, W1_RESUME_CMD); return 0; } EXPORT_SYMBOL_GPL(w1_reset_resume_command); /** |
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* Put out a strong pull-up of the specified duration after the next write * operation. Not all hardware supports strong pullups. Hardware that * doesn't support strong pullups will sleep for the given time after the * write operation without a strong pullup. This is a one shot request for * the next write, specifying zero will clear a previous request. * The w1 master lock must be held. * * @param delay time in milliseconds * @return 0=success, anything else=error */ void w1_next_pullup(struct w1_master *dev, int delay) { dev->pullup_duration = delay; } EXPORT_SYMBOL_GPL(w1_next_pullup); |