Hi
17.04.2016, 02:08, "x29a" <0.x29...@googlemail.com>:
> based on the PR (https://github.com/raspberrypi/linux/pull/1412) for the
> raspberry pi kernel, i would like to propose my changes upstream as well.
>
> The changes entitle basic write operations for the 1Wire driver which are
> needed to change e.g. the precision of temperature sensors like the very
> popular DS18B20. Writing to SRAM and commiting the values to EEPROM is
> possible.
>
> Since many sensors come "preconfigured" with a lower precision, people are
> stuck 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 looks good to me, Greg, please pull it into your tree
> Signed-off-by: x29a <0.x29...@gmail.com>
Acked-by: Evgeniy Polyakov <z...@ioremap.net>
> ---
> Documentation/w1/slaves/w1_therm | 10 +-
> drivers/w1/slaves/w1_therm.c | 218 +++++++++++++++++++++++++++++++++++++--
> drivers/w1/w1.h | 2 +
> 3 files changed, 222 insertions(+), 8 deletions(-)
>
> diff --git a/Documentation/w1/slaves/w1_therm
> b/Documentation/w1/slaves/w1_therm
> index 13411fe..d1f93af 100644
> --- a/Documentation/w1/slaves/w1_therm
> +++ b/Documentation/w1/slaves/w1_therm
> @@ -33,7 +33,15 @@ temperature conversion at a time. If none of the devices
> are parasite
> powered it would be possible to convert all the devices at the same
> time and then go back to read individual sensors. That isn't
> currently supported. The driver also doesn't support reduced
> -precision (which would also reduce the conversion time).
> +precision (which would also reduce the conversion time) when reading values.
> +
> +Writing a value between 9 and 12 to the sysfs w1_slave file will change the
> +precision of the sensor for the next readings. This value is in (volatile)
> +SRAM, so it is reset when the sensor gets power-cycled.
> +
> +To store the current precision configuration into EEPROM, the value 0
> +has to be written to the sysfs w1_slave file. Since the EEPROM has a limited
> +amount of writes (>50k), this command should be used wisely.
>
> The module parameter strong_pullup can be set to 0 to disable the
> strong pullup, 1 to enable autodetection or 2 to force strong pullup.
> diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c
> index 2f029e8..581a300 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 56a49ba..129895f 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
> --
> 2.5.0
