diff options
Diffstat (limited to 'drivers/w1/slaves/w1_therm.c')
| -rw-r--r-- | drivers/w1/slaves/w1_therm.c | 106 |
1 files changed, 78 insertions, 28 deletions
diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c index 9b2d96335a70..f6b0e0320ffc 100644 --- a/drivers/w1/slaves/w1_therm.c +++ b/drivers/w1/slaves/w1_therm.c @@ -80,6 +80,18 @@ static u16 bulk_read_device_counter; /* =0 as per C standard */ #define W1_POLL_CONVERT_TEMP 2000 /* Timeout for W1_CONVERT_TEMP, ms */ #define W1_POLL_RECALL_EEPROM 500 /* Timeout for W1_RECALL_EEPROM, ms*/ +/* Masks for resolution functions, work with all devices */ +/* Bit mask for config register for all devices, bits 7,6,5 */ +#define W1_THERM_RESOLUTION_MASK 0xE0 +/* Bit offset of resolution in config register for all devices */ +#define W1_THERM_RESOLUTION_SHIFT 5 +/* Bit offset of resolution in config register for all devices */ +#define W1_THERM_RESOLUTION_SHIFT 5 +/* Add this to bit value to get resolution */ +#define W1_THERM_RESOLUTION_MIN 9 +/* Maximum allowed value */ +#define W1_THERM_RESOLUTION_MAX 14 + /* Helpers Macros */ /* @@ -523,7 +535,9 @@ static inline int w1_DS18B20_convert_time(struct w1_slave *sl) if (SLAVE_CONV_TIME_OVERRIDE(sl) != CONV_TIME_DEFAULT) return SLAVE_CONV_TIME_OVERRIDE(sl); - /* Return the conversion time from datasheet, depending on resolution */ + /* Return the conversion time, depending on resolution, + * select maximum conversion time among all compatible devices + */ switch (SLAVE_RESOLUTION(sl)) { case 9: ret = 95; @@ -535,6 +549,14 @@ static inline int w1_DS18B20_convert_time(struct w1_slave *sl) ret = 375; break; case 12: + ret = 750; + break; + case 13: + ret = 850; /* GX20MH01 only. Datasheet says 500ms, but that's not enough. */ + break; + case 14: + ret = 1600; /* GX20MH01 only. Datasheet says 1000ms - not enough */ + break; default: ret = 750; } @@ -568,62 +590,71 @@ static inline int w1_DS18S20_write_data(struct w1_slave *sl, static inline int w1_DS18B20_set_resolution(struct w1_slave *sl, int val) { int ret; - u8 new_config_register[3]; /* array of data to be written */ struct therm_info info, info2; - /* resolution of DS18B20 is in the range [9..12] bits */ - if (val < 9 || val > 12) + /* DS18B20 resolution is 9 to 12 bits */ + /* GX20MH01 resolution is 9 to 14 bits */ + if (val < W1_THERM_RESOLUTION_MIN || val > W1_THERM_RESOLUTION_MAX) return -EINVAL; - val -= 9; /* soustract 9 the lowest resolution in bit */ - val = (val << 5); /* shift to position bit 5 & bit 6 */ + /* Calc bit value from resolution */ + val = (val - W1_THERM_RESOLUTION_MIN) << W1_THERM_RESOLUTION_SHIFT; /* * Read the scratchpad to change only the required bits * (bit5 & bit 6 from byte 4) */ ret = read_scratchpad(sl, &info); - if (!ret) { - new_config_register[0] = info.rom[2]; - new_config_register[1] = info.rom[3]; - /* config register is byte 4 & mask 0b10011111*/ - new_config_register[2] = (info.rom[4] & 0x9F) | - (u8) val; - } else + + if (ret) return ret; + + info.rom[4] &= ~W1_THERM_RESOLUTION_MASK; + info.rom[4] |= val; + /* Write data in the device RAM */ - ret = w1_DS18B20_write_data(sl, new_config_register); + ret = w1_DS18B20_write_data(sl, info.rom + 2); if (ret) return ret; - /* Some DS18B20 clones don't support resolution change, read back to verify */ + /* Have to read back the resolution to verify an actual value + * GX20MH01 and DS18B20 are indistinguishable by family number, but resolutions differ + * Some DS18B20 clones don't support resolution change + */ ret = read_scratchpad(sl, &info2); if (ret) + /* Scratchpad read fail */ return ret; - if ((info2.rom[4] & 0x9F) == (info.rom[4] & 0x9F)) + if ((info2.rom[4] & W1_THERM_RESOLUTION_MASK) == (info.rom[4] & W1_THERM_RESOLUTION_MASK)) return 0; - else - return -EIO; + + /* Resolution verify error */ + return -EIO; } static inline int w1_DS18B20_get_resolution(struct w1_slave *sl) { int ret; - u8 config_register; + int resolution; struct therm_info info; ret = read_scratchpad(sl, &info); - if (!ret) { - config_register = info.rom[4]; /* config register is byte 4 */ - config_register &= 0x60; /* 0b01100000 keep only bit 5 & 6 */ - config_register = (config_register >> 5); /* shift */ - config_register += 9; /* add 9 the lowest resolution in bit */ - ret = (int) config_register; - } - return ret; + if (ret) + return ret; + + resolution = ((info.rom[4] & W1_THERM_RESOLUTION_MASK) >> W1_THERM_RESOLUTION_SHIFT) + + W1_THERM_RESOLUTION_MIN; + /* GX20MH01 has one special case: + * >=14 means 14 bits when getting resolution from bit value. + * Other devices have no more then 12 bits. + */ + if (resolution > W1_THERM_RESOLUTION_MAX) + resolution = W1_THERM_RESOLUTION_MAX; + + return resolution; } /** @@ -636,11 +667,28 @@ static inline int w1_DS18B20_get_resolution(struct w1_slave *sl) */ static inline int w1_DS18B20_convert_temp(u8 rom[9]) { - s16 t = le16_to_cpup((__le16 *)rom); + int t; + u32 bv; + + /* Config register bit R2 = 1 - GX20MH01 in 13 or 14 bit resolution mode */ + if (rom[4] & 0x80) { + /* Signed 16-bit value to unsigned, cpu order */ + bv = le16_to_cpup((__le16 *)rom); + + /* Insert two temperature bits from config register */ + /* Avoid arithmetic shift of signed value */ + bv = (bv << 2) | (rom[4] & 3); + t = (int) sign_extend32(bv, 17); /* Degrees, lowest bit is 2^-6 */ + return (t*1000)/64; /* Millidegrees */ + } + + t = (int)le16_to_cpup((__le16 *)rom); return t*1000/16; } + + /** * w1_DS18S20_convert_temp() - temperature computation for DS18S20 * @rom: data read from device RAM (8 data bytes + 1 CRC byte) @@ -672,6 +720,7 @@ static inline int w1_DS18S20_convert_temp(u8 rom[9]) } /* Device capability description */ +/* GX20MH01 device shares family number and structure with DS18B20 */ static struct w1_therm_family_converter w1_therm_families[] = { { @@ -693,6 +742,7 @@ static struct w1_therm_family_converter w1_therm_families[] = { .bulk_read = true }, { + /* Also used for GX20MH01 */ .f = &w1_therm_family_DS18B20, .convert = w1_DS18B20_convert_temp, .get_conversion_time = w1_DS18B20_convert_time, |