diff options
Diffstat (limited to 'drivers/w1/slaves/w1_therm.c')
| -rw-r--r-- | drivers/w1/slaves/w1_therm.c | 36 |
1 files changed, 16 insertions, 20 deletions
diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c index 92d08e7fcba..c1a702f8c80 100644 --- a/drivers/w1/slaves/w1_therm.c +++ b/drivers/w1/slaves/w1_therm.c @@ -41,14 +41,18 @@ MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol, temperature famil * If it was disabled a parasite powered device might not get the require * current to do a temperature conversion. If it is enabled parasite powered * devices have a better chance of getting the current required. + * In case the parasite power-detection is not working (seems to be the case + * for some DS18S20) the strong pullup can also be forced, regardless of the + * power state of the devices. + * + * Summary of options: + * - strong_pullup = 0 Disable strong pullup completely + * - strong_pullup = 1 Enable automatic strong pullup detection + * - strong_pullup = 2 Force strong pullup */ static int w1_strong_pullup = 1; module_param_named(strong_pullup, w1_strong_pullup, int, 0); -static u8 bad_roms[][9] = { - {0xaa, 0x00, 0x4b, 0x46, 0xff, 0xff, 0x0c, 0x10, 0x87}, - {} - }; static ssize_t w1_therm_read(struct device *device, struct device_attribute *attr, char *buf); @@ -168,16 +172,6 @@ static inline int w1_convert_temp(u8 rom[9], u8 fid) return 0; } -static int w1_therm_check_rom(u8 rom[9]) -{ - int i; - - for (i=0; i<sizeof(bad_roms)/9; ++i) - if (!memcmp(bad_roms[i], rom, 9)) - return 1; - - return 0; -} static ssize_t w1_therm_read(struct device *device, struct device_attribute *attr, char *buf) @@ -194,10 +188,11 @@ static ssize_t w1_therm_read(struct device *device, memset(rom, 0, sizeof(rom)); - verdict = 0; - crc = 0; - while (max_trying--) { + + verdict = 0; + crc = 0; + if (!w1_reset_select_slave(sl)) { int count = 0; unsigned int tm = 750; @@ -210,7 +205,8 @@ static ssize_t w1_therm_read(struct device *device, continue; /* 750ms strong pullup (or delay) after the convert */ - if (!external_power && w1_strong_pullup) + if (w1_strong_pullup == 2 || + (!external_power && w1_strong_pullup)) w1_next_pullup(dev, tm); w1_write_8(dev, W1_CONVERT_TEMP); @@ -249,7 +245,7 @@ static ssize_t w1_therm_read(struct device *device, } } - if (!w1_therm_check_rom(rom)) + if (verdict) break; } @@ -260,7 +256,7 @@ static ssize_t w1_therm_read(struct device *device, if (verdict) memcpy(sl->rom, rom, sizeof(sl->rom)); else - dev_warn(device, "18S20 doesn't respond to CONVERT_TEMP.\n"); + dev_warn(device, "Read failed CRC check\n"); for (i = 0; i < 9; ++i) c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", sl->rom[i]); |