hwmon: Add support for the sl28cpld hardware monitoring controller

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>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index 750d3a9..d90c43c 100644 (file)
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -154,6 +154,7 @@ 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 (file)
index 0000000..7ed65f7
--- /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 8dc28b2..d98c0a6 100644 (file)
--- 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 a8f4b35..dee8511 100644 (file)
--- 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 (file)
index 0000000..e48f58e
--- /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");