diff options
| -rw-r--r-- | Documentation/ABI/testing/sysfs-driver-w1_therm | 12 | ||||
| -rw-r--r-- | drivers/w1/slaves/w1_therm.c | 137 |
2 files changed, 149 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-driver-w1_therm b/Documentation/ABI/testing/sysfs-driver-w1_therm index 4a856631aaf9..99d73eeee3db 100644 --- a/Documentation/ABI/testing/sysfs-driver-w1_therm +++ b/Documentation/ABI/testing/sysfs-driver-w1_therm @@ -1,3 +1,15 @@ +What: /sys/bus/w1/devices/.../ext_power +Date: May 2020 +Contact: Akira Shimahara <akira215corp@gmail.com> +Description: + (RO) return the power status by asking the device + * '0': device parasite powered + * '1': device externally powered + * '-xx': xx is kernel error when reading power status +Users: any user space application which wants to communicate with + w1_term device + + What: /sys/bus/w1/devices/.../w1_slave Date: May 2020 Contact: Akira Shimahara <akira215corp@gmail.com> diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c index aa5678369c0b..932a0738b52a 100644 --- a/drivers/w1/slaves/w1_therm.c +++ b/drivers/w1/slaves/w1_therm.c @@ -43,8 +43,21 @@ static int w1_strong_pullup = 1; module_param_named(strong_pullup, w1_strong_pullup, int, 0); +/* Nb of try for an operation */ +#define W1_THERM_MAX_TRY 5 + +/* ms delay to retry bus mutex */ +#define W1_THERM_RETRY_DELAY 20 + /* Helpers Macros */ +/* + * return the power mode of the sl slave : 1-ext, 0-parasite, <0 unknown + * always test family data existence before using this macro + */ +#define SLAVE_POWERMODE(sl) \ + (((struct w1_therm_family_data *)(sl->family_data))->external_powered) + /* return the address of the refcnt in the family data */ #define THERM_REFCNT(family_data) \ (&((struct w1_therm_family_data *)family_data)->refcnt) @@ -73,10 +86,14 @@ struct w1_therm_family_converter { * struct w1_therm_family_data - device data * @rom: ROM device id (64bit Lasered ROM code + 1 CRC byte) * @refcnt: ref count + * @external_powered: 1 device powered externally, + * 0 device parasite powered, + * -x error or undefined */ struct w1_therm_family_data { uint8_t rom[9]; atomic_t refcnt; + int external_powered; }; /** @@ -109,6 +126,20 @@ struct therm_info { */ static int reset_select_slave(struct w1_slave *sl); +/** + * read_powermode() - Query the power mode of the slave + * @sl: slave to retrieve the power mode + * + * Ask the device to get its power mode (external or parasite) + * and store the power status in the &struct w1_therm_family_data. + * + * Return: + * * 0 parasite powered device + * * 1 externally powered device + * * <0 kernel error code + */ +static int read_powermode(struct w1_slave *sl); + /* Sysfs interface declaration */ static ssize_t w1_slave_show(struct device *device, @@ -120,10 +151,14 @@ static ssize_t w1_slave_store(struct device *device, static ssize_t w1_seq_show(struct device *device, struct device_attribute *attr, char *buf); +static ssize_t ext_power_show(struct device *device, + struct device_attribute *attr, char *buf); + /* Attributes declarations */ static DEVICE_ATTR_RW(w1_slave); static DEVICE_ATTR_RO(w1_seq); +static DEVICE_ATTR_RO(ext_power); /* Interface Functions declaration */ @@ -151,12 +186,14 @@ static void w1_therm_remove_slave(struct w1_slave *sl); static struct attribute *w1_therm_attrs[] = { &dev_attr_w1_slave.attr, + &dev_attr_ext_power.attr, NULL, }; static struct attribute *w1_ds28ea00_attrs[] = { &dev_attr_w1_slave.attr, &dev_attr_w1_seq.attr, + &dev_attr_ext_power.attr, NULL, }; @@ -433,6 +470,34 @@ static struct w1_therm_family_converter w1_therm_families[] = { /* Helpers Functions */ /** + * bus_mutex_lock() - Acquire the mutex + * @lock: w1 bus mutex to acquire + * + * It try to acquire the mutex W1_THERM_MAX_TRY times and wait + * W1_THERM_RETRY_DELAY between 2 attempts. + * + * Return: true is mutex is acquired and lock, false otherwise + */ +static inline bool bus_mutex_lock(struct mutex *lock) +{ + int max_trying = W1_THERM_MAX_TRY; + + /* try to acquire the mutex, if not, sleep retry_delay before retry) */ + while (mutex_lock_interruptible(lock) != 0 && max_trying > 0) { + unsigned long sleep_rem; + + sleep_rem = msleep_interruptible(W1_THERM_RETRY_DELAY); + if (!sleep_rem) + max_trying--; + } + + if (!max_trying) + return false; /* Didn't acquire the bus mutex */ + + return true; +} + +/** * w1_convert_temp() - temperature conversion binding function * @rom: data read from device RAM (8 data bytes + 1 CRC byte) * @fid: device family id @@ -461,7 +526,19 @@ static int w1_therm_add_slave(struct w1_slave *sl) GFP_KERNEL); if (!sl->family_data) return -ENOMEM; + atomic_set(THERM_REFCNT(sl->family_data), 1); + + /* Getting the power mode of the device {external, parasite} */ + SLAVE_POWERMODE(sl) = read_powermode(sl); + + if (SLAVE_POWERMODE(sl) < 0) { + /* no error returned as device has been added */ + dev_warn(&sl->dev, + "%s: Device has been added, but power_mode may be corrupted. err=%d\n", + __func__, SLAVE_POWERMODE(sl)); + } + return 0; } @@ -661,6 +738,44 @@ error: return ret; } +static int read_powermode(struct w1_slave *sl) +{ + struct w1_master *dev_master = sl->master; + int max_trying = W1_THERM_MAX_TRY; + int ret = -ENODEV; + + if (!sl->family_data) + goto error; + + /* prevent the slave from going away in sleep */ + atomic_inc(THERM_REFCNT(sl->family_data)); + + if (!bus_mutex_lock(&dev_master->bus_mutex)) { + ret = -EAGAIN; /* Didn't acquire the mutex */ + goto dec_refcnt; + } + + while ((max_trying--) && (ret < 0)) { + /* safe version to select slave */ + if (!reset_select_slave(sl)) { + w1_write_8(dev_master, W1_READ_PSUPPLY); + /* + * Emit a read time slot and read only one bit, + * 1 is externally powered, + * 0 is parasite powered + */ + ret = w1_touch_bit(dev_master, 1); + /* ret should be either 1 either 0 */ + } + } + mutex_unlock(&dev_master->bus_mutex); + +dec_refcnt: + atomic_dec(THERM_REFCNT(sl->family_data)); +error: + return ret; +} + /* Sysfs Interface definition */ static ssize_t w1_slave_show(struct device *device, @@ -722,6 +837,28 @@ static ssize_t w1_slave_store(struct device *device, return ret ? : size; } +static ssize_t ext_power_show(struct device *device, + struct device_attribute *attr, char *buf) +{ + struct w1_slave *sl = dev_to_w1_slave(device); + + if (!sl->family_data) { + dev_info(device, + "%s: Device not supported by the driver\n", __func__); + return 0; /* No device family */ + } + + /* Getting the power mode of the device {external, parasite} */ + SLAVE_POWERMODE(sl) = read_powermode(sl); + + if (SLAVE_POWERMODE(sl) < 0) { + dev_dbg(device, + "%s: Power_mode may be corrupted. err=%d\n", + __func__, SLAVE_POWERMODE(sl)); + } + return sprintf(buf, "%d\n", SLAVE_POWERMODE(sl)); +} + #if IS_REACHABLE(CONFIG_HWMON) static int w1_read_temp(struct device *device, u32 attr, int channel, long *val) |