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f07e572f64
bcm2708: boot tested on RPi B+ v1.2 bcm2709: boot tested on RPi 3B v1.2 and RPi 4B v1.1 4G bcm2710: boot tested on RPi 3B v1.2 bcm2711: boot tested on RPi 4B v1.1 4G Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
294 lines
8.6 KiB
Diff
294 lines
8.6 KiB
Diff
From 5737e27d3c5e2f743421e68f926c05e8581ae21f Mon Sep 17 00:00:00 2001
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From: Akira Shimahara <akira215corp@gmail.com>
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Date: Mon, 11 May 2020 22:36:50 +0200
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Subject: [PATCH] w1_therm: adding ext_power sysfs entry
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commit b7bb6ca17a90f47c2fe2848531b5bbaf27a65ba7 upstream.
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Adding ext_power sysfs entry (RO). Return the power status of the device:
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- 0: device parasite powered
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- 1: device externally powered
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- xx: xx is kernel error
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The power status of each device is check when the device is
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discover by the bus master, in 'w1_therm_add_slave(struct w1_slave *)'.
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The status is stored in the device structure w1_therm_family_data so
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that the driver always knows the power state of each device, which could
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be used later to determine the required strong pull up to apply on the
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line.
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The power status is re evaluate each time the sysfs ext_power read by
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a user.
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The hardware function 'read_powermode(struct w1_slave *sl)' act just as
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per device specifications, sending W1_READ_PSUPPLY command on the bus,
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and issue a read time slot, reading only one bit.
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A helper function 'bool bus_mutex_lock(struct mutex *lock)' is introduced.
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It try to aquire the bus mutex several times (W1_THERM_MAX_TRY), waiting
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W1_THERM_RETRY_DELAY between two attempt.
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Updating Documentation/ABI/testing/sysfs-driver-w1_therm accordingly.
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Signed-off-by: Akira Shimahara <akira215corp@gmail.com>
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Link: https://lore.kernel.org/r/20200511203650.410439-1-akira215corp@gmail.com
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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---
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.../ABI/testing/sysfs-driver-w1_therm | 29 ++++
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drivers/w1/slaves/w1_therm.c | 137 ++++++++++++++++++
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2 files changed, 166 insertions(+)
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create mode 100644 Documentation/ABI/testing/sysfs-driver-w1_therm
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--- /dev/null
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+++ b/Documentation/ABI/testing/sysfs-driver-w1_therm
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@@ -0,0 +1,29 @@
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+What: /sys/bus/w1/devices/.../ext_power
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+Date: May 2020
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+Contact: Akira Shimahara <akira215corp@gmail.com>
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+Description:
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+ (RO) return the power status by asking the device
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+ * '0': device parasite powered
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+ * '1': device externally powered
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+ * '-xx': xx is kernel error when reading power status
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+Users: any user space application which wants to communicate with
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+ w1_term device
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+
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+
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+What: /sys/bus/w1/devices/.../w1_slave
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+Date: May 2020
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+Contact: Akira Shimahara <akira215corp@gmail.com>
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+Description:
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+ (RW) return the temperature in 1/1000 degC.
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+ *read*: return 2 lines with the hexa output data sent on the
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+ bus, return the CRC check and temperature in 1/1000 degC
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+ *write* :
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+ * '0' : save the 2 or 3 bytes to the device EEPROM
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+ (i.e. TH, TL and config register)
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+ * '9..12' : set the device resolution in RAM
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+ (if supported)
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+ * Anything else: do nothing
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+ refer to Documentation/w1/slaves/w1_therm.rst for detailed
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+ information.
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+Users: any user space application which wants to communicate with
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+ w1_term device
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\ No newline at end of file
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--- a/drivers/w1/slaves/w1_therm.c
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+++ b/drivers/w1/slaves/w1_therm.c
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@@ -43,8 +43,21 @@
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static int w1_strong_pullup = 1;
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module_param_named(strong_pullup, w1_strong_pullup, int, 0);
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+/* Nb of try for an operation */
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+#define W1_THERM_MAX_TRY 5
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+
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+/* ms delay to retry bus mutex */
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+#define W1_THERM_RETRY_DELAY 20
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+
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/* Helpers Macros */
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+/*
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+ * return the power mode of the sl slave : 1-ext, 0-parasite, <0 unknown
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+ * always test family data existence before using this macro
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+ */
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+#define SLAVE_POWERMODE(sl) \
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+ (((struct w1_therm_family_data *)(sl->family_data))->external_powered)
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+
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/* return the address of the refcnt in the family data */
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#define THERM_REFCNT(family_data) \
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(&((struct w1_therm_family_data *)family_data)->refcnt)
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@@ -73,10 +86,14 @@ struct w1_therm_family_converter {
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* struct w1_therm_family_data - device data
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* @rom: ROM device id (64bit Lasered ROM code + 1 CRC byte)
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* @refcnt: ref count
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+ * @external_powered: 1 device powered externally,
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+ * 0 device parasite powered,
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+ * -x error or undefined
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*/
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struct w1_therm_family_data {
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uint8_t rom[9];
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atomic_t refcnt;
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+ int external_powered;
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};
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/**
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@@ -109,6 +126,20 @@ struct therm_info {
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*/
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static int reset_select_slave(struct w1_slave *sl);
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+/**
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+ * read_powermode() - Query the power mode of the slave
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+ * @sl: slave to retrieve the power mode
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+ *
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+ * Ask the device to get its power mode (external or parasite)
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+ * and store the power status in the &struct w1_therm_family_data.
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+ *
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+ * Return:
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+ * * 0 parasite powered device
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+ * * 1 externally powered device
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+ * * <0 kernel error code
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+ */
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+static int read_powermode(struct w1_slave *sl);
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+
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/* Sysfs interface declaration */
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static ssize_t w1_slave_show(struct device *device,
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@@ -120,10 +151,14 @@ static ssize_t w1_slave_store(struct dev
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static ssize_t w1_seq_show(struct device *device,
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struct device_attribute *attr, char *buf);
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+static ssize_t ext_power_show(struct device *device,
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+ struct device_attribute *attr, char *buf);
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+
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/* Attributes declarations */
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static DEVICE_ATTR_RW(w1_slave);
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static DEVICE_ATTR_RO(w1_seq);
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+static DEVICE_ATTR_RO(ext_power);
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/* Interface Functions declaration */
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@@ -151,12 +186,14 @@ static void w1_therm_remove_slave(struct
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static struct attribute *w1_therm_attrs[] = {
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&dev_attr_w1_slave.attr,
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+ &dev_attr_ext_power.attr,
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NULL,
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};
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static struct attribute *w1_ds28ea00_attrs[] = {
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&dev_attr_w1_slave.attr,
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&dev_attr_w1_seq.attr,
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+ &dev_attr_ext_power.attr,
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NULL,
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};
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@@ -433,6 +470,34 @@ static struct w1_therm_family_converter
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/* Helpers Functions */
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/**
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+ * bus_mutex_lock() - Acquire the mutex
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+ * @lock: w1 bus mutex to acquire
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+ *
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+ * It try to acquire the mutex W1_THERM_MAX_TRY times and wait
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+ * W1_THERM_RETRY_DELAY between 2 attempts.
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+ *
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+ * Return: true is mutex is acquired and lock, false otherwise
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+ */
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+static inline bool bus_mutex_lock(struct mutex *lock)
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+{
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+ int max_trying = W1_THERM_MAX_TRY;
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+
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+ /* try to acquire the mutex, if not, sleep retry_delay before retry) */
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+ while (mutex_lock_interruptible(lock) != 0 && max_trying > 0) {
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+ unsigned long sleep_rem;
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+
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+ sleep_rem = msleep_interruptible(W1_THERM_RETRY_DELAY);
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+ if (!sleep_rem)
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+ max_trying--;
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+ }
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+
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+ if (!max_trying)
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+ return false; /* Didn't acquire the bus mutex */
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+
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+ return true;
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+}
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+
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+/**
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* w1_convert_temp() - temperature conversion binding function
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* @rom: data read from device RAM (8 data bytes + 1 CRC byte)
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* @fid: device family id
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@@ -461,7 +526,19 @@ static int w1_therm_add_slave(struct w1_
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GFP_KERNEL);
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if (!sl->family_data)
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return -ENOMEM;
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+
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atomic_set(THERM_REFCNT(sl->family_data), 1);
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+
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+ /* Getting the power mode of the device {external, parasite} */
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+ SLAVE_POWERMODE(sl) = read_powermode(sl);
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+
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+ if (SLAVE_POWERMODE(sl) < 0) {
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+ /* no error returned as device has been added */
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+ dev_warn(&sl->dev,
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+ "%s: Device has been added, but power_mode may be corrupted. err=%d\n",
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+ __func__, SLAVE_POWERMODE(sl));
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+ }
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+
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return 0;
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}
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@@ -661,6 +738,44 @@ error:
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return ret;
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}
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+static int read_powermode(struct w1_slave *sl)
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+{
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+ struct w1_master *dev_master = sl->master;
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+ int max_trying = W1_THERM_MAX_TRY;
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+ int ret = -ENODEV;
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+
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+ if (!sl->family_data)
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+ goto error;
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+
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+ /* prevent the slave from going away in sleep */
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+ atomic_inc(THERM_REFCNT(sl->family_data));
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+
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+ if (!bus_mutex_lock(&dev_master->bus_mutex)) {
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+ ret = -EAGAIN; /* Didn't acquire the mutex */
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+ goto dec_refcnt;
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+ }
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+
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+ while ((max_trying--) && (ret < 0)) {
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+ /* safe version to select slave */
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+ if (!reset_select_slave(sl)) {
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+ w1_write_8(dev_master, W1_READ_PSUPPLY);
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+ /*
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+ * Emit a read time slot and read only one bit,
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+ * 1 is externally powered,
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+ * 0 is parasite powered
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+ */
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+ ret = w1_touch_bit(dev_master, 1);
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+ /* ret should be either 1 either 0 */
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+ }
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+ }
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+ mutex_unlock(&dev_master->bus_mutex);
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+
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+dec_refcnt:
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+ atomic_dec(THERM_REFCNT(sl->family_data));
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+error:
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+ return ret;
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+}
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+
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/* Sysfs Interface definition */
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static ssize_t w1_slave_show(struct device *device,
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@@ -722,6 +837,28 @@ static ssize_t w1_slave_store(struct dev
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return ret ? : size;
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}
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+static ssize_t ext_power_show(struct device *device,
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+ struct device_attribute *attr, char *buf)
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+{
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+ struct w1_slave *sl = dev_to_w1_slave(device);
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+
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+ if (!sl->family_data) {
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+ dev_info(device,
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+ "%s: Device not supported by the driver\n", __func__);
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+ return 0; /* No device family */
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+ }
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+
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+ /* Getting the power mode of the device {external, parasite} */
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+ SLAVE_POWERMODE(sl) = read_powermode(sl);
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+
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+ if (SLAVE_POWERMODE(sl) < 0) {
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+ dev_dbg(device,
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+ "%s: Power_mode may be corrupted. err=%d\n",
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+ __func__, SLAVE_POWERMODE(sl));
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+ }
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+ return sprintf(buf, "%d\n", SLAVE_POWERMODE(sl));
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+}
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+
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#if IS_REACHABLE(CONFIG_HWMON)
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static int w1_read_temp(struct device *device, u32 attr, int channel,
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long *val)
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