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Subject[PATCH v9 08/13] hwmon: add support for the sl28cpld hardware monitoring controller
Date
Add support for the hardware monitoring controller of the sl28cpld board
management controller. This driver is part of a multi-function device.

Signed-off-by: Michael Walle <michael@walle.cc>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
Changes since v8:
- none

Changes since v7:
- added "depends on MFD_SL28CPLD || COMPILE_TEST"

Changes since v6:
- none

Changes since v5:
- none

Changes since v4:
- update copyright year
- remove #include <linux/of_device.h>, suggested by Andy.
- use PTR_ERR_OR_ZERO(), suggested by Andy.
- remove the platform device table
- don't use KBUID_MODNAME

Changes since v3:
- see cover letter

Documentation/hwmon/index.rst | 1 +
Documentation/hwmon/sl28cpld.rst | 36 ++++++++
drivers/hwmon/Kconfig | 10 +++
drivers/hwmon/Makefile | 1 +
drivers/hwmon/sl28cpld-hwmon.c | 142 +++++++++++++++++++++++++++++++
5 files changed, 190 insertions(+)
create mode 100644 Documentation/hwmon/sl28cpld.rst
create mode 100644 drivers/hwmon/sl28cpld-hwmon.c

diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index af064a9ad42f..f6064e98fde1 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -155,6 +155,7 @@ Hardware Monitoring Kernel Drivers
sht3x
shtc1
sis5595
+ sl28cpld
smm665
smsc47b397
smsc47m192
diff --git a/Documentation/hwmon/sl28cpld.rst b/Documentation/hwmon/sl28cpld.rst
new file mode 100644
index 000000000000..7ed65f78250c
--- /dev/null
+++ b/Documentation/hwmon/sl28cpld.rst
@@ -0,0 +1,36 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+Kernel driver sl28cpld
+======================
+
+Supported chips:
+
+ * Kontron sl28cpld
+
+ Prefix: 'sl28cpld'
+
+ Datasheet: not available
+
+Authors: Michael Walle <michael@walle.cc>
+
+Description
+-----------
+
+The sl28cpld is a board management controller which also exposes a hardware
+monitoring controller. At the moment this controller supports a single fan
+supervisor. In the future there might be other flavours and additional
+hardware monitoring might be supported.
+
+The fan supervisor has a 7 bit counter register and a counter period of 1
+second. If the 7 bit counter overflows, the supervisor will automatically
+switch to x8 mode to support a wider input range at the loss of
+granularity.
+
+Sysfs entries
+-------------
+
+The following attributes are supported.
+
+======================= ========================================================
+fan1_input Fan RPM. Assuming 2 pulses per revolution.
+======================= ========================================================
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 8dc28b26916e..d98c0a6860d1 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1479,6 +1479,16 @@ config SENSORS_RASPBERRYPI_HWMON
This driver can also be built as a module. If so, the module
will be called raspberrypi-hwmon.

+config SENSORS_SL28CPLD
+ tristate "Kontron sl28cpld hardware monitoring driver"
+ depends on MFD_SL28CPLD || COMPILE_TEST
+ help
+ If you say yes here you get support for the fan supervisor of the
+ sl28cpld board management controller.
+
+ This driver can also be built as a module. If so, the module
+ will be called sl28cpld-hwmon.
+
config SENSORS_SHT15
tristate "Sensiron humidity and temperature sensors. SHT15 and compat."
depends on GPIOLIB || COMPILE_TEST
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index a8f4b35b136b..dee8511f9348 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -159,6 +159,7 @@ obj-$(CONFIG_SENSORS_S3C) += s3c-hwmon.o
obj-$(CONFIG_SENSORS_SCH56XX_COMMON)+= sch56xx-common.o
obj-$(CONFIG_SENSORS_SCH5627) += sch5627.o
obj-$(CONFIG_SENSORS_SCH5636) += sch5636.o
+obj-$(CONFIG_SENSORS_SL28CPLD) += sl28cpld-hwmon.o
obj-$(CONFIG_SENSORS_SHT15) += sht15.o
obj-$(CONFIG_SENSORS_SHT21) += sht21.o
obj-$(CONFIG_SENSORS_SHT3x) += sht3x.o
diff --git a/drivers/hwmon/sl28cpld-hwmon.c b/drivers/hwmon/sl28cpld-hwmon.c
new file mode 100644
index 000000000000..e48f58ec5b9c
--- /dev/null
+++ b/drivers/hwmon/sl28cpld-hwmon.c
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * sl28cpld hardware monitoring driver
+ *
+ * Copyright 2020 Kontron Europe GmbH
+ */
+
+#include <linux/bitfield.h>
+#include <linux/hwmon.h>
+#include <linux/kernel.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+
+#define FAN_INPUT 0x00
+#define FAN_SCALE_X8 BIT(7)
+#define FAN_VALUE_MASK GENMASK(6, 0)
+
+struct sl28cpld_hwmon {
+ struct regmap *regmap;
+ u32 offset;
+};
+
+static umode_t sl28cpld_hwmon_is_visible(const void *data,
+ enum hwmon_sensor_types type,
+ u32 attr, int channel)
+{
+ return 0444;
+}
+
+static int sl28cpld_hwmon_read(struct device *dev,
+ enum hwmon_sensor_types type, u32 attr,
+ int channel, long *input)
+{
+ struct sl28cpld_hwmon *hwmon = dev_get_drvdata(dev);
+ unsigned int value;
+ int ret;
+
+ switch (attr) {
+ case hwmon_fan_input:
+ ret = regmap_read(hwmon->regmap, hwmon->offset + FAN_INPUT,
+ &value);
+ if (ret)
+ return ret;
+ /*
+ * The register has a 7 bit value and 1 bit which indicates the
+ * scale. If the MSB is set, then the lower 7 bit has to be
+ * multiplied by 8, to get the correct reading.
+ */
+ if (value & FAN_SCALE_X8)
+ value = FIELD_GET(FAN_VALUE_MASK, value) << 3;
+
+ /*
+ * The counter period is 1000ms and the sysfs specification
+ * says we should asssume 2 pulses per revolution.
+ */
+ value *= 60 / 2;
+
+ break;
+ default:
+ return -EOPNOTSUPP;
+ }
+
+ *input = value;
+ return 0;
+}
+
+static const u32 sl28cpld_hwmon_fan_config[] = {
+ HWMON_F_INPUT,
+ 0
+};
+
+static const struct hwmon_channel_info sl28cpld_hwmon_fan = {
+ .type = hwmon_fan,
+ .config = sl28cpld_hwmon_fan_config,
+};
+
+static const struct hwmon_channel_info *sl28cpld_hwmon_info[] = {
+ &sl28cpld_hwmon_fan,
+ NULL
+};
+
+static const struct hwmon_ops sl28cpld_hwmon_ops = {
+ .is_visible = sl28cpld_hwmon_is_visible,
+ .read = sl28cpld_hwmon_read,
+};
+
+static const struct hwmon_chip_info sl28cpld_hwmon_chip_info = {
+ .ops = &sl28cpld_hwmon_ops,
+ .info = sl28cpld_hwmon_info,
+};
+
+static int sl28cpld_hwmon_probe(struct platform_device *pdev)
+{
+ struct sl28cpld_hwmon *hwmon;
+ struct device *hwmon_dev;
+ int ret;
+
+ if (!pdev->dev.parent)
+ return -ENODEV;
+
+ hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL);
+ if (!hwmon)
+ return -ENOMEM;
+
+ hwmon->regmap = dev_get_regmap(pdev->dev.parent, NULL);
+ if (!hwmon->regmap)
+ return -ENODEV;
+
+ ret = device_property_read_u32(&pdev->dev, "reg", &hwmon->offset);
+ if (ret)
+ return -EINVAL;
+
+ hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
+ "sl28cpld_hwmon", hwmon,
+ &sl28cpld_hwmon_chip_info, NULL);
+ if (IS_ERR(hwmon_dev))
+ dev_err(&pdev->dev, "failed to register as hwmon device");
+
+ return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct of_device_id sl28cpld_hwmon_of_match[] = {
+ { .compatible = "kontron,sl28cpld-fan" },
+ {}
+};
+MODULE_DEVICE_TABLE(of, sl28cpld_hwmon_of_match);
+
+static struct platform_driver sl28cpld_hwmon_driver = {
+ .probe = sl28cpld_hwmon_probe,
+ .driver = {
+ .name = "sl28cpld-fan",
+ .of_match_table = sl28cpld_hwmon_of_match,
+ },
+};
+module_platform_driver(sl28cpld_hwmon_driver);
+
+MODULE_DESCRIPTION("sl28cpld Hardware Monitoring Driver");
+MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
+MODULE_LICENSE("GPL");
--
2.20.1
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