diff options
Diffstat (limited to 'drivers/w1/slaves/w1_ds2423.c')
| -rw-r--r-- | drivers/w1/slaves/w1_ds2423.c | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/drivers/w1/slaves/w1_ds2423.c b/drivers/w1/slaves/w1_ds2423.c new file mode 100644 index 0000000..7a7dbe5 --- /dev/null +++ b/drivers/w1/slaves/w1_ds2423.c @@ -0,0 +1,166 @@ +/* + * w1_ds2423.c + * + * Copyright (c) 2010 Mika Laitio <lamikr@pilppa.org> + * + * This driver will read and write the value of 4 counters to w1_slave file in + * sys filesystem. + * Inspired by the w1_therm and w1_ds2431 drivers. + * + * This program is free software; you can redistribute it and/or modify + * it under the therms 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 <linux/kernel.h> +#include <linux/module.h> +#include <linux/moduleparam.h> +#include <linux/device.h> +#include <linux/types.h> +#include <linux/delay.h> +#include <linux/crc16.h> + +#include "../w1.h" +#include "../w1_int.h" +#include "../w1_family.h" + +#define CRC16_VALID 0xb001 +#define CRC16_INIT 0 + +#define COUNTER_COUNT 4 +#define READ_BYTE_COUNT 42 + +static ssize_t w1_counter_read(struct device *device, + struct device_attribute *attr, char *buf); + +static struct device_attribute w1_counter_attr = + __ATTR(w1_slave, S_IRUGO, w1_counter_read, NULL); + +static ssize_t w1_counter_read(struct device *device, + struct device_attribute *attr, char *out_buf) +{ + struct w1_slave *sl = dev_to_w1_slave(device); + struct w1_master *dev = sl->master; + u8 rbuf[COUNTER_COUNT * READ_BYTE_COUNT]; + u8 wrbuf[3]; + int rom_addr; + int read_byte_count; + int result; + ssize_t c; + int ii; + int p; + int crc; + + c = PAGE_SIZE; + rom_addr = (12 << 5) + 31; + wrbuf[0] = 0xA5; + wrbuf[1] = rom_addr & 0xFF; + wrbuf[2] = rom_addr >> 8; + mutex_lock(&dev->mutex); + if (!w1_reset_select_slave(sl)) { + w1_write_block(dev, wrbuf, 3); + read_byte_count = 0; + for (p = 0; p < 4; p++) { + /* + * 1 byte for first bytes in ram page read + * 4 bytes for counter + * 4 bytes for zero bits + * 2 bytes for crc + * 31 remaining bytes from the ram page + */ + read_byte_count += w1_read_block(dev, + rbuf + (p * READ_BYTE_COUNT), READ_BYTE_COUNT); + for (ii = 0; ii < READ_BYTE_COUNT; ++ii) + c -= snprintf(out_buf + PAGE_SIZE - c, + c, "%02x ", + rbuf[(p * READ_BYTE_COUNT) + ii]); + if (read_byte_count != (p + 1) * READ_BYTE_COUNT) { + dev_warn(device, + "w1_counter_read() returned %u bytes " + "instead of %d bytes wanted.\n", + read_byte_count, + READ_BYTE_COUNT); + c -= snprintf(out_buf + PAGE_SIZE - c, + c, "crc=NO\n"); + } else { + if (p == 0) { + crc = crc16(CRC16_INIT, wrbuf, 3); + crc = crc16(crc, rbuf, 11); + } else { + /* + * DS2423 calculates crc from all bytes + * read after the previous crc bytes. + */ + crc = crc16(CRC16_INIT, + (rbuf + 11) + + ((p - 1) * READ_BYTE_COUNT), + READ_BYTE_COUNT); + } + if (crc == CRC16_VALID) { + result = 0; + for (ii = 4; ii > 0; ii--) { + result <<= 8; + result |= rbuf[(p * + READ_BYTE_COUNT) + ii]; + } + c -= snprintf(out_buf + PAGE_SIZE - c, + c, "crc=YES c=%d\n", result); + } else { + c -= snprintf(out_buf + PAGE_SIZE - c, + c, "crc=NO\n"); + } + } + } + } else { + c -= snprintf(out_buf + PAGE_SIZE - c, c, "Connection error"); + } + mutex_unlock(&dev->mutex); + return PAGE_SIZE - c; +} + +static int w1_f1d_add_slave(struct w1_slave *sl) +{ + return device_create_file(&sl->dev, &w1_counter_attr); +} + +static void w1_f1d_remove_slave(struct w1_slave *sl) +{ + device_remove_file(&sl->dev, &w1_counter_attr); +} + +static struct w1_family_ops w1_f1d_fops = { + .add_slave = w1_f1d_add_slave, + .remove_slave = w1_f1d_remove_slave, +}; + +static struct w1_family w1_family_1d = { + .fid = W1_COUNTER_DS2423, + .fops = &w1_f1d_fops, +}; + +static int __init w1_f1d_init(void) +{ + return w1_register_family(&w1_family_1d); +} + +static void __exit w1_f1d_exit(void) +{ + w1_unregister_family(&w1_family_1d); +} + +module_init(w1_f1d_init); +module_exit(w1_f1d_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Mika Laitio <lamikr@pilppa.org>"); +MODULE_DESCRIPTION("w1 family 1d driver for DS2423, 4 counters and 4kb ram"); |