diff options
Diffstat (limited to 'drivers/w1/slaves/w1_ds2408.c')
| -rw-r--r-- | drivers/w1/slaves/w1_ds2408.c | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/drivers/w1/slaves/w1_ds2408.c b/drivers/w1/slaves/w1_ds2408.c index 91cc2cdf02c..cb8a8e5d957 100644 --- a/drivers/w1/slaves/w1_ds2408.c +++ b/drivers/w1/slaves/w1_ds2408.c @@ -302,7 +302,33 @@ error: return -EIO; } +/* + * This is a special sequence we must do to ensure the P0 output is not stuck + * in test mode. This is described in rev 2 of the ds2408's datasheet + * (http://datasheets.maximintegrated.com/en/ds/DS2408.pdf) under + * "APPLICATION INFORMATION/Power-up timing". + */ +static int w1_f29_disable_test_mode(struct w1_slave *sl) +{ + int res; + u8 magic[10] = {0x96, }; + u64 rn = le64_to_cpu(*((u64*)&sl->reg_num)); + + memcpy(&magic[1], &rn, 8); + magic[9] = 0x3C; + + mutex_lock(&sl->master->bus_mutex); + res = w1_reset_bus(sl->master); + if (res) + goto out; + w1_write_block(sl->master, magic, ARRAY_SIZE(magic)); + + res = w1_reset_bus(sl->master); +out: + mutex_unlock(&sl->master->bus_mutex); + return res; +} static struct bin_attribute w1_f29_sysfs_bin_files[] = { { @@ -363,6 +389,10 @@ static int w1_f29_add_slave(struct w1_slave *sl) int err = 0; int i; + err = w1_f29_disable_test_mode(sl); + if (err) + return err; + for (i = 0; i < ARRAY_SIZE(w1_f29_sysfs_bin_files) && !err; ++i) err = sysfs_create_bin_file( &sl->dev.kobj, |