| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <Yg7R0PtS4oyyZFC/@hatter.bewilderbeest.net>
Date: Thu, 17 Feb 2022 14:53:04 -0800
From: Zev Weiss <zev@...ilderbeest.net>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Arnd Bergmann <arnd@...db.de>, openbmc@...ts.ozlabs.org,
linux-kernel@...r.kernel.org, Guenter Roeck <linux@...ck-us.net>,
Jean Delvare <jdelvare@...e.com>, linux-hwmon@...r.kernel.org,
Mark Brown <broonie@...nel.org>,
Liam Girdwood <lgirdwood@...il.com>
Subject: Re: [PATCH 4/4] misc: Add power-efuse driver
On Thu, Feb 17, 2022 at 05:34:56AM PST, Greg Kroah-Hartman wrote:
>On Thu, Feb 17, 2022 at 02:44:44AM -0800, Zev Weiss wrote:
>> This driver provides a sysfs interface to access the on/off state and
>> error flags of a regulator supplying a power output controlled by the
>> system.
>>
>> Signed-off-by: Zev Weiss <zev@...ilderbeest.net>
>> ---
>> MAINTAINERS | 5 +
>> drivers/misc/Kconfig | 15 +++
>> drivers/misc/Makefile | 1 +
>> drivers/misc/power-efuse.c | 221 +++++++++++++++++++++++++++++++++++++
>> 4 files changed, 242 insertions(+)
>> create mode 100644 drivers/misc/power-efuse.c
>
>You add sysfs files, yet have no Documentation/ABI/ entry updates
>documenting what those sysfs files do? Please fix.
>
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index fca970a46e77..d1153a0389d2 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -7064,6 +7064,11 @@ S: Orphan
>> W: http://aeschi.ch.eu.org/efs/
>> F: fs/efs/
>>
>> +POWER EFUSE DRIVER
>> +M: Zev Weiss <zev@...ilderbeest.net>
>> +S: Maintained
>> +F: drivers/misc/power-efuse.c
>> +
>> EHEA (IBM pSeries eHEA 10Gb ethernet adapter) DRIVER
>> M: Douglas Miller <dougmill@...ux.ibm.com>
>> L: netdev@...r.kernel.org
>> diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
>> index 0f5a49fc7c9e..45fc3e8ad35d 100644
>> --- a/drivers/misc/Kconfig
>> +++ b/drivers/misc/Kconfig
>> @@ -470,6 +470,21 @@ config HISI_HIKEY_USB
>> switching between the dual-role USB-C port and the USB-A host ports
>> using only one USB controller.
>>
>> +config POWER_EFUSE
>> + tristate "Power efuse driver support"
>> + depends on OF && REGULATOR
>> + help
>> + This driver supports a regulator device functioning as a
>> + power efuse, with status bits and an on/off switch available
>> + via sysfs.
>> +
>> + A typical use for this would be for an efuse controlling a
>> + generic power output for supplying power to devices external
>> + to the system running this driver (such as in the management
>> + controller of a "smart" PDU or similar), allowing the
>> + operator to manually turn the output on and off, check if
>> + the efuse has tripped due to overload, etc.
>> +
>> source "drivers/misc/c2port/Kconfig"
>> source "drivers/misc/eeprom/Kconfig"
>> source "drivers/misc/cb710/Kconfig"
>> diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
>> index a086197af544..7bd784b89ef8 100644
>> --- a/drivers/misc/Makefile
>> +++ b/drivers/misc/Makefile
>> @@ -59,3 +59,4 @@ obj-$(CONFIG_UACCE) += uacce/
>> obj-$(CONFIG_XILINX_SDFEC) += xilinx_sdfec.o
>> obj-$(CONFIG_HISI_HIKEY_USB) += hisi_hikey_usb.o
>> obj-$(CONFIG_HI6421V600_IRQ) += hi6421v600-irq.o
>> +obj-$(CONFIG_POWER_EFUSE) += power-efuse.o
>> diff --git a/drivers/misc/power-efuse.c b/drivers/misc/power-efuse.c
>> new file mode 100644
>> index 000000000000..e974dde57615
>> --- /dev/null
>> +++ b/drivers/misc/power-efuse.c
>> @@ -0,0 +1,221 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * This module provides a thin wrapper around a regulator device that exposes
>> + * status bits and on/off state via sysfs.
>> + *
>> + * Copyright (C) 2022 Zev Weiss <zev@...ilderbeest.net>
>> + */
>> +
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/regulator/consumer.h>
>> +
>> +struct efuse {
>> + struct regulator *reg;
>> + struct {
>> + unsigned int cache;
>> + unsigned long ttl;
>> + unsigned long fetch_time;
>> + struct mutex lock;
>> + } error_flags;
>> +};
>> +
>> +/* Ensure that the next error_flags access fetches them from the device */
>> +static void efuse_invalidate_error_flags(struct efuse *efuse)
>> +{
>> + mutex_lock(&efuse->error_flags.lock);
>> + efuse->error_flags.fetch_time = 0;
>> + mutex_unlock(&efuse->error_flags.lock);
>> +}
>> +
>> +static ssize_t efuse_show_operstate(struct device *dev, struct device_attribute *attr,
>> + char *buf)
>> +{
>> + struct efuse *efuse = dev_get_drvdata(dev);
>> + int status = regulator_is_enabled(efuse->reg);
>> +
>> + if (status < 0)
>> + return status;
>> +
>> + return sysfs_emit(buf, "%s\n", status ? "on" : "off");
>> +}
>> +
>> +static ssize_t efuse_set_operstate(struct device *dev, struct device_attribute *attr,
>> + const char *buf, size_t count)
>> +{
>> + int status, wantstate;
>> + struct efuse *efuse = dev_get_drvdata(dev);
>> + struct regulator *reg = efuse->reg;
>> +
>> + if (sysfs_streq(buf, "on"))
>> + wantstate = 1;
>> + else if (sysfs_streq(buf, "off"))
>> + wantstate = 0;
>> + else
>> + return -EINVAL;
>> +
>> + status = regulator_is_enabled(reg);
>> +
>> + /*
>> + * We need to ensure our enable/disable calls don't get imbalanced, so
>> + * bail if we can't determine the current state.
>> + */
>> + if (status < 0)
>> + return status;
>> +
>> + /* Return early if we're already in the desired state */
>> + if (!!status == wantstate)
>> + return count;
>> +
>> + if (wantstate)
>> + status = regulator_enable(reg);
>> + else
>> + status = regulator_disable(reg);
>> +
>> + /*
>> + * Toggling operstate can reset latched status flags, so invalidate
>> + * the cached value.
>> + */
>> + efuse_invalidate_error_flags(efuse);
>> +
>> + if (!status && regulator_is_enabled(reg) != wantstate) {
>> + /*
>> + * We could do
>> + *
>> + * if (!wantstate)
>> + * regulator_force_disable(reg);
>> + *
>> + * here, but it's likely to leave it such that it can't then
>> + * be re-enabled, so we'll just report the error and leave it
>> + * as it is (and hopefully as long as our enable/disable calls
>> + * remain balanced and nobody registers another consumer for
>> + * the same supply we won't end up in this situation anyway).
>> + */
>> + dev_err(dev, "regulator_%sable() didn't take effect\n", wantstate ? "en" : "dis");
>> + status = -EIO;
>> + }
>> +
>> + return status ? : count;
>> +}
>> +
>> +static int efuse_update_error_flags(struct efuse *efuse)
>> +{
>> + int status = 0;
>> + unsigned long cache_expiry;
>> +
>> + mutex_lock(&efuse->error_flags.lock);
>> +
>> + cache_expiry = efuse->error_flags.fetch_time + efuse->error_flags.ttl;
>> +
>> + if (!efuse->error_flags.ttl || !efuse->error_flags.fetch_time ||
>> + time_after(jiffies, cache_expiry)) {
>> + status = regulator_get_error_flags(efuse->reg, &efuse->error_flags.cache);
>> + if (!status)
>> + efuse->error_flags.fetch_time = jiffies;
>> + }
>> +
>> + mutex_unlock(&efuse->error_flags.lock);
>> +
>> + return status;
>> +}
>> +
>> +static DEVICE_ATTR(operstate, 0644, efuse_show_operstate, efuse_set_operstate);
>> +
>> +#define EFUSE_ERROR_ATTR(name, bit) \
>> + static ssize_t efuse_show_##name(struct device *dev, struct device_attribute *attr, \
>> + char *buf) \
>> + { \
>> + struct efuse *efuse = dev_get_drvdata(dev); \
>> + int status = efuse_update_error_flags(efuse); \
>> + if (status) \
>> + return status; \
>> + return sysfs_emit(buf, "%d\n", !!(efuse->error_flags.cache & bit)); \
>> + } \
>> + static DEVICE_ATTR(name, 0444, efuse_show_##name, NULL)
>> +
>> +EFUSE_ERROR_ATTR(under_voltage, REGULATOR_ERROR_UNDER_VOLTAGE);
>> +EFUSE_ERROR_ATTR(over_current, REGULATOR_ERROR_OVER_CURRENT);
>> +EFUSE_ERROR_ATTR(regulation_out, REGULATOR_ERROR_REGULATION_OUT);
>> +EFUSE_ERROR_ATTR(fail, REGULATOR_ERROR_FAIL);
>> +EFUSE_ERROR_ATTR(over_temp, REGULATOR_ERROR_OVER_TEMP);
>> +EFUSE_ERROR_ATTR(under_voltage_warn, REGULATOR_ERROR_UNDER_VOLTAGE_WARN);
>> +EFUSE_ERROR_ATTR(over_current_warn, REGULATOR_ERROR_OVER_CURRENT_WARN);
>> +EFUSE_ERROR_ATTR(over_voltage_warn, REGULATOR_ERROR_OVER_VOLTAGE_WARN);
>> +EFUSE_ERROR_ATTR(over_temp_warn, REGULATOR_ERROR_OVER_TEMP_WARN);
>> +
>> +static struct attribute *attributes[] = {
>> + &dev_attr_operstate.attr,
>> + &dev_attr_under_voltage.attr,
>> + &dev_attr_over_current.attr,
>> + &dev_attr_regulation_out.attr,
>> + &dev_attr_fail.attr,
>> + &dev_attr_over_temp.attr,
>> + &dev_attr_under_voltage_warn.attr,
>> + &dev_attr_over_current_warn.attr,
>> + &dev_attr_over_voltage_warn.attr,
>> + &dev_attr_over_temp_warn.attr,
>> + NULL,
>> +};
>> +
>> +static const struct attribute_group attr_group = {
>> + .attrs = attributes,
>> +};
>
>ATTRIBUTE_GROUPS()?
>
>> +
>> +static int efuse_probe(struct platform_device *pdev)
>> +{
>> + int status;
>> + struct regulator *reg;
>> + struct efuse *efuse;
>> + u32 cache_ttl_ms;
>> +
>> + reg = devm_regulator_get(&pdev->dev, "vout");
>> + if (IS_ERR(reg))
>> + return PTR_ERR(reg);
>> +
>> + status = regulator_enable(reg);
>> + if (status) {
>> + dev_err(&pdev->dev, "failed to enable regulator\n");
>> + return status;
>> + }
>> +
>> + efuse = devm_kzalloc(&pdev->dev, sizeof(*efuse), GFP_KERNEL);
>> + if (!efuse)
>> + return -ENOMEM;
>> +
>> + efuse->reg = reg;
>> + mutex_init(&efuse->error_flags.lock);
>> +
>> + if (!of_property_read_u32(pdev->dev.of_node, "error-flags-cache-ttl-ms", &cache_ttl_ms))
>> + efuse->error_flags.ttl = msecs_to_jiffies(cache_ttl_ms);
>> +
>> + platform_set_drvdata(pdev, efuse);
>> +
>> + return sysfs_create_group(&pdev->dev.kobj, &attr_group);
>
>You just raced with userspace and lost :(
>
>Set the default groups for your platform driver and then the driver core
>will automatically create/remove them for you, no need for you to do
>anything directly with them at all.
>
Ack, thanks for the review -- I'll fix all three points in v2.
Zev
Powered by blists - more mailing lists