diff options
Diffstat (limited to 'drivers/w1/slaves/w1_therm.c')
| -rw-r--r-- | drivers/w1/slaves/w1_therm.c | 48 |
1 files changed, 41 insertions, 7 deletions
diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c index 1234916daaa8..aa5678369c0b 100644 --- a/drivers/w1/slaves/w1_therm.c +++ b/drivers/w1/slaves/w1_therm.c @@ -16,6 +16,7 @@ #include <linux/slab.h> #include <linux/delay.h> #include <linux/hwmon.h> +#include <linux/string.h> #include <linux/w1.h> @@ -90,6 +91,24 @@ struct therm_info { u8 verdict; }; +/* Hardware Functions declaration */ + +/** + * reset_select_slave() - reset and select a slave + * @sl: the slave to select + * + * Resets the bus and select the slave by sending a ROM MATCH cmd + * w1_reset_select_slave() from w1_io.c could not be used here because + * it sent a SKIP ROM command if only one device is on the line. + * At the beginning of the such process, sl->master->slave_count is 1 even if + * more devices are on the line, causing collision on the line. + * + * Context: The w1 master lock must be held. + * + * Return: 0 if success, negative kernel error code otherwise. + */ +static int reset_select_slave(struct w1_slave *sl); + /* Sysfs interface declaration */ static ssize_t w1_slave_show(struct device *device, @@ -301,7 +320,7 @@ static inline int w1_DS18B20_precision(struct device *device, int val) while (max_trying--) { crc = 0; - if (!w1_reset_select_slave(sl)) { + if (!reset_select_slave(sl)) { int count = 0; /* read values to only alter precision bits */ @@ -314,7 +333,7 @@ static inline int w1_DS18B20_precision(struct device *device, int val) if (rom[8] == crc) { rom[4] = (rom[4] & ~mask) | (precision_bits & mask); - if (!w1_reset_select_slave(sl)) { + if (!reset_select_slave(sl)) { w1_write_8(dev, W1_WRITE_SCRATCHPAD); w1_write_8(dev, rom[2]); w1_write_8(dev, rom[3]); @@ -460,6 +479,21 @@ static void w1_therm_remove_slave(struct w1_slave *sl) /* Hardware Functions */ +/* Safe version of reset_select_slave - avoid using the one in w_io.c */ +static int reset_select_slave(struct w1_slave *sl) +{ + u8 match[9] = { W1_MATCH_ROM, }; + u64 rn = le64_to_cpu(*((u64 *)&sl->reg_num)); + + if (w1_reset_bus(sl->master)) + return -ENODEV; + + memcpy(&match[1], &rn, 8); + w1_write_block(sl->master, match, 9); + + return 0; +} + static ssize_t read_therm(struct device *device, struct w1_slave *sl, struct therm_info *info) { @@ -487,7 +521,7 @@ static ssize_t read_therm(struct device *device, info->verdict = 0; info->crc = 0; - if (!w1_reset_select_slave(sl)) { + if (!reset_select_slave(sl)) { int count = 0; unsigned int tm = 750; unsigned long sleep_rem; @@ -495,7 +529,7 @@ static ssize_t read_therm(struct device *device, w1_write_8(dev, W1_READ_PSUPPLY); external_power = w1_read_8(dev); - if (w1_reset_select_slave(sl)) + if (reset_select_slave(sl)) continue; /* 750ms strong pullup (or delay) after the convert */ @@ -525,7 +559,7 @@ static ssize_t read_therm(struct device *device, } } - if (!w1_reset_select_slave(sl)) { + if (!reset_select_slave(sl)) { w1_write_8(dev, W1_READ_SCRATCHPAD); count = w1_read_block(dev, info->rom, 9); @@ -577,7 +611,7 @@ static inline int w1_therm_eeprom(struct device *device) memset(rom, 0, sizeof(rom)); while (max_trying--) { - if (!w1_reset_select_slave(sl)) { + if (!reset_select_slave(sl)) { unsigned int tm = 10; unsigned long sleep_rem; @@ -585,7 +619,7 @@ static inline int w1_therm_eeprom(struct device *device) w1_write_8(dev, W1_READ_PSUPPLY); external_power = w1_read_8(dev); - if (w1_reset_select_slave(sl)) + if (reset_select_slave(sl)) continue; /* 10ms strong pullup/delay after the copy command */ |