From 0a19f129d71f18e73249d54de96c835186b8607e Mon Sep 17 00:00:00 2001 From: Ben Sen Date: Sun, 1 May 2016 23:23:33 +0200 Subject: w1: add ability to set (SRAM) and store (EEPROM) configuration for temp sensors like DS18B20 Since many temperature sensors come "preconfigured" with a lower precision, people are stuck at that precision when running on a kernel based device (unlike the Dallas 1Wire library for e.g. Arduino, which supports writing the configuration/scratchpad). This patch adds write support for the scratchpad/precision registers via w1_slave sysfs. Signed-off-by: Ben Sen <0.x29a.0@gmail.com> Acked-by: Evgeniy Polyakov Signed-off-by: Greg Kroah-Hartman --- drivers/w1/slaves/w1_therm.c | 218 +++++++++++++++++++++++++++++++++++++++++-- drivers/w1/w1.h | 2 + 2 files changed, 213 insertions(+), 7 deletions(-) (limited to 'drivers/w1') diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c index 2f029e8f4f95..581a300fd6cd 100644 --- a/drivers/w1/slaves/w1_therm.c +++ b/drivers/w1/slaves/w1_therm.c @@ -92,10 +92,13 @@ static void w1_therm_remove_slave(struct w1_slave *sl) static ssize_t w1_slave_show(struct device *device, struct device_attribute *attr, char *buf); +static ssize_t w1_slave_store(struct device *device, + struct device_attribute *attr, const char *buf, size_t size); + static ssize_t w1_seq_show(struct device *device, struct device_attribute *attr, char *buf); -static DEVICE_ATTR_RO(w1_slave); +static DEVICE_ATTR_RW(w1_slave); static DEVICE_ATTR_RO(w1_seq); static struct attribute *w1_therm_attrs[] = { @@ -154,8 +157,17 @@ struct w1_therm_family_converter u16 reserved; struct w1_family *f; int (*convert)(u8 rom[9]); + int (*precision)(struct device *device, int val); + int (*eeprom)(struct device *device); }; +/* write configuration to eeprom */ +static inline int w1_therm_eeprom(struct device *device); + +/* Set precision for conversion */ +static inline int w1_DS18B20_precision(struct device *device, int val); +static inline int w1_DS18S20_precision(struct device *device, int val); + /* The return value is millidegrees Centigrade. */ static inline int w1_DS18B20_convert_temp(u8 rom[9]); static inline int w1_DS18S20_convert_temp(u8 rom[9]); @@ -163,26 +175,194 @@ static inline int w1_DS18S20_convert_temp(u8 rom[9]); static struct w1_therm_family_converter w1_therm_families[] = { { .f = &w1_therm_family_DS18S20, - .convert = w1_DS18S20_convert_temp + .convert = w1_DS18S20_convert_temp, + .precision = w1_DS18S20_precision, + .eeprom = w1_therm_eeprom }, { .f = &w1_therm_family_DS1822, - .convert = w1_DS18B20_convert_temp + .convert = w1_DS18B20_convert_temp, + .precision = w1_DS18S20_precision, + .eeprom = w1_therm_eeprom }, { .f = &w1_therm_family_DS18B20, - .convert = w1_DS18B20_convert_temp + .convert = w1_DS18B20_convert_temp, + .precision = w1_DS18B20_precision, + .eeprom = w1_therm_eeprom }, { .f = &w1_therm_family_DS28EA00, - .convert = w1_DS18B20_convert_temp + .convert = w1_DS18B20_convert_temp, + .precision = w1_DS18S20_precision, + .eeprom = w1_therm_eeprom }, { .f = &w1_therm_family_DS1825, - .convert = w1_DS18B20_convert_temp + .convert = w1_DS18B20_convert_temp, + .precision = w1_DS18S20_precision, + .eeprom = w1_therm_eeprom } }; +static inline int w1_therm_eeprom(struct device *device) +{ + struct w1_slave *sl = dev_to_w1_slave(device); + struct w1_master *dev = sl->master; + u8 rom[9], external_power; + int ret, max_trying = 10; + u8 *family_data = sl->family_data; + + ret = mutex_lock_interruptible(&dev->bus_mutex); + if (ret != 0) + goto post_unlock; + + if (!sl->family_data) { + ret = -ENODEV; + goto pre_unlock; + } + + /* prevent the slave from going away in sleep */ + atomic_inc(THERM_REFCNT(family_data)); + memset(rom, 0, sizeof(rom)); + + while (max_trying--) { + if (!w1_reset_select_slave(sl)) { + unsigned int tm = 10; + unsigned long sleep_rem; + + /* check if in parasite mode */ + w1_write_8(dev, W1_READ_PSUPPLY); + external_power = w1_read_8(dev); + + if (w1_reset_select_slave(sl)) + continue; + + /* 10ms strong pullup/delay after the copy command */ + if (w1_strong_pullup == 2 || + (!external_power && w1_strong_pullup)) + w1_next_pullup(dev, tm); + + w1_write_8(dev, W1_COPY_SCRATCHPAD); + + if (external_power) { + mutex_unlock(&dev->bus_mutex); + + sleep_rem = msleep_interruptible(tm); + if (sleep_rem != 0) { + ret = -EINTR; + goto post_unlock; + } + + ret = mutex_lock_interruptible(&dev->bus_mutex); + if (ret != 0) + goto post_unlock; + } else if (!w1_strong_pullup) { + sleep_rem = msleep_interruptible(tm); + if (sleep_rem != 0) { + ret = -EINTR; + goto pre_unlock; + } + } + + break; + } + } + +pre_unlock: + mutex_unlock(&dev->bus_mutex); + +post_unlock: + atomic_dec(THERM_REFCNT(family_data)); + return ret; +} + +/* DS18S20 does not feature configuration register */ +static inline int w1_DS18S20_precision(struct device *device, int val) +{ + return 0; +} + +static inline int w1_DS18B20_precision(struct device *device, int val) +{ + struct w1_slave *sl = dev_to_w1_slave(device); + struct w1_master *dev = sl->master; + u8 rom[9], crc; + int ret, max_trying = 10; + u8 *family_data = sl->family_data; + uint8_t precision_bits; + uint8_t mask = 0x60; + + if(val > 12 || val < 9) { + pr_warn("Unsupported precision\n"); + return -1; + } + + ret = mutex_lock_interruptible(&dev->bus_mutex); + if (ret != 0) + goto post_unlock; + + if (!sl->family_data) { + ret = -ENODEV; + goto pre_unlock; + } + + /* prevent the slave from going away in sleep */ + atomic_inc(THERM_REFCNT(family_data)); + memset(rom, 0, sizeof(rom)); + + /* translate precision to bitmask (see datasheet page 9) */ + switch (val) { + case 9: + precision_bits = 0x00; + break; + case 10: + precision_bits = 0x20; + break; + case 11: + precision_bits = 0x40; + break; + case 12: + default: + precision_bits = 0x60; + break; + } + + while (max_trying--) { + crc = 0; + + if (!w1_reset_select_slave(sl)) { + int count = 0; + + /* read values to only alter precision bits */ + w1_write_8(dev, W1_READ_SCRATCHPAD); + if ((count = w1_read_block(dev, rom, 9)) != 9) + dev_warn(device, "w1_read_block() returned %u instead of 9.\n", count); + + crc = w1_calc_crc8(rom, 8); + if (rom[8] == crc) { + rom[4] = (rom[4] & ~mask) | (precision_bits & mask); + + if (!w1_reset_select_slave(sl)) { + w1_write_8(dev, W1_WRITE_SCRATCHPAD); + w1_write_8(dev, rom[2]); + w1_write_8(dev, rom[3]); + w1_write_8(dev, rom[4]); + + break; + } + } + } + } + +pre_unlock: + mutex_unlock(&dev->bus_mutex); + +post_unlock: + atomic_dec(THERM_REFCNT(family_data)); + return ret; +} + static inline int w1_DS18B20_convert_temp(u8 rom[9]) { s16 t = le16_to_cpup((__le16 *)rom); @@ -220,6 +400,30 @@ static inline int w1_convert_temp(u8 rom[9], u8 fid) return 0; } +static ssize_t w1_slave_store(struct device *device, + struct device_attribute *attr, const char *buf, + size_t size) +{ + int val, ret; + struct w1_slave *sl = dev_to_w1_slave(device); + int i; + + ret = kstrtoint(buf, 0, &val); + if (ret) + return ret; + + for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) { + if (w1_therm_families[i].f->fid == sl->family->fid) { + /* zero value indicates to write current configuration to eeprom */ + if (0 == val) + ret = w1_therm_families[i].eeprom(device); + else + ret = w1_therm_families[i].precision(device, val); + break; + } + } + return ret ? : size; +} static ssize_t w1_slave_show(struct device *device, struct device_attribute *attr, char *buf) @@ -311,7 +515,7 @@ static ssize_t w1_slave_show(struct device *device, for (i = 0; i < 9; ++i) c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", rom[i]); c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n", - crc, (verdict) ? "YES" : "NO"); + crc, (verdict) ? "YES" : "NO"); if (verdict) memcpy(family_data, rom, sizeof(rom)); else diff --git a/drivers/w1/w1.h b/drivers/w1/w1.h index 56a49ba41d83..129895f562b0 100644 --- a/drivers/w1/w1.h +++ b/drivers/w1/w1.h @@ -58,6 +58,8 @@ struct w1_reg_num #define W1_ALARM_SEARCH 0xEC #define W1_CONVERT_TEMP 0x44 #define W1_SKIP_ROM 0xCC +#define W1_COPY_SCRATCHPAD 0x48 +#define W1_WRITE_SCRATCHPAD 0x4E #define W1_READ_SCRATCHPAD 0xBE #define W1_READ_ROM 0x33 #define W1_READ_PSUPPLY 0xB4 -- cgit v1.2.3-55-g7522