hwmon: (gxp-fan-ctrl) Add GXP fan controller

The GXP SoC can support up to 16 fans through the interface provided by
the CPLD. The current support is limited to 8 fans. The fans speeds are
controlled via 8 different PWMs which can vary in value from  0-255. The
fans are also capable of reporting if they have failed to the CPLD which
in turn reports the status to the GXP SoC.

Signed-off-by: Nick Hawkins <nick.hawkins@hpe.com>
Link: https://lore.kernel.org/r/20230103203654.59322-2-nick.hawkins@hpe.com
[groeck: Improved alignment of defined, added missing include linux/bits.h]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/gxp-fan-ctrl.rst

@@ -0,0 +1,28 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+Kernel driver gxp-fan-ctrl
+==========================
+
+Supported chips:
+
+  * HPE GXP SOC
+
+Author: Nick Hawkins <nick.hawkins@hpe.com>
+
+
+Description
+-----------
+
+gxp-fan-ctrl is a driver which provides fan control for the hpe gxp soc.
+The driver allows the gathering of fan status and the use of fan
+PWM control.
+
+
+Sysfs attributes
+----------------
+
+======================= ===========================================================
+pwm[0-7]		Fan 0 to 7 respective PWM value (0-255)
+fan[0-7]_fault		Fan 0 to 7 respective fault status: 1 fail, 0 ok
+fan[0-7]_enable         Fan 0 to 7 respective enabled status: 1 enabled, 0 disabled
+======================= ===========================================================

Documentation/hwmon/index.rst

@@ -73,6 +73,7 @@ Hardware Monitoring Kernel Drivers
    g762
    gsc-hwmon
    gl518sm
+   gxp-fan-ctrl
    hih6130
    ibmaem
    ibm-cffps

drivers/hwmon/Kconfig

@@ -714,6 +714,15 @@ config SENSORS_GPIO_FAN
 	  This driver can also be built as a module. If so, the module
 	  will be called gpio-fan.
 
+config SENSORS_GXP_FAN_CTRL
+	tristate "HPE GXP fan controller"
+	depends on ARCH_HPE_GXP || COMPILE_TEST
+	help
+	  If you say yes here you get support for GXP fan control functionality.
+
+	  The GXP controls fan function via the CPLD through the use of PWM
+	  registers. This driver reports status and pwm setting of the fans.
+
 config SENSORS_HIH6130
 	tristate "Honeywell Humidicon HIH-6130 humidity/temperature sensor"
 	depends on I2C

drivers/hwmon/Makefile

@@ -83,6 +83,7 @@ obj-$(CONFIG_SENSORS_GL518SM)	+= gl518sm.o
 obj-$(CONFIG_SENSORS_GL520SM)	+= gl520sm.o
 obj-$(CONFIG_SENSORS_GSC)	+= gsc-hwmon.o
 obj-$(CONFIG_SENSORS_GPIO_FAN)	+= gpio-fan.o
+obj-$(CONFIG_SENSORS_GXP_FAN_CTRL) += gxp-fan-ctrl.o
 obj-$(CONFIG_SENSORS_HIH6130)	+= hih6130.o
 obj-$(CONFIG_SENSORS_ULTRA45)	+= ultra45_env.o
 obj-$(CONFIG_SENSORS_I5500)	+= i5500_temp.o

drivers/hwmon/gxp-fan-ctrl.c

@@ -0,0 +1,255 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (C) 2022 Hewlett-Packard Enterprise Development Company, L.P. */
+
+#include <linux/bits.h>
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+
+#define OFS_FAN_INST	0 /* Is 0 because plreg base will be set at INST */
+#define OFS_FAN_FAIL	2 /* Is 2 bytes after base */
+#define OFS_SEVSTAT	0 /* Is 0 because fn2 base will be set at SEVSTAT */
+#define POWER_BIT	24
+
+struct gxp_fan_ctrl_drvdata {
+	void __iomem	*base;
+	void __iomem	*plreg;
+	void __iomem	*fn2;
+};
+
+static bool fan_installed(struct device *dev, int fan)
+{
+	struct gxp_fan_ctrl_drvdata *drvdata = dev_get_drvdata(dev);
+	u8 val;
+
+	val = readb(drvdata->plreg + OFS_FAN_INST);
+
+	return !!(val & BIT(fan));
+}
+
+static long fan_failed(struct device *dev, int fan)
+{
+	struct gxp_fan_ctrl_drvdata *drvdata = dev_get_drvdata(dev);
+	u8 val;
+
+	val = readb(drvdata->plreg + OFS_FAN_FAIL);
+
+	return !!(val & BIT(fan));
+}
+
+static long fan_enabled(struct device *dev, int fan)
+{
+	struct gxp_fan_ctrl_drvdata *drvdata = dev_get_drvdata(dev);
+	u32 val;
+
+	/*
+	 * Check the power status as if the platform is off the value
+	 * reported for the PWM will be incorrect. Report fan as
+	 * disabled.
+	 */
+	val = readl(drvdata->fn2 + OFS_SEVSTAT);
+
+	return !!((val & BIT(POWER_BIT)) && fan_installed(dev, fan));
+}
+
+static int gxp_pwm_write(struct device *dev, u32 attr, int channel, long val)
+{
+	struct gxp_fan_ctrl_drvdata *drvdata = dev_get_drvdata(dev);
+
+	switch (attr) {
+	case hwmon_pwm_input:
+		if (val > 255 || val < 0)
+			return -EINVAL;
+		writeb(val, drvdata->base + channel);
+		return 0;
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static int gxp_fan_ctrl_write(struct device *dev, enum hwmon_sensor_types type,
+			      u32 attr, int channel, long val)
+{
+	switch (type) {
+	case hwmon_pwm:
+		return gxp_pwm_write(dev, attr, channel, val);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static int gxp_fan_read(struct device *dev, u32 attr, int channel, long *val)
+{
+	switch (attr) {
+	case hwmon_fan_enable:
+		*val = fan_enabled(dev, channel);
+		return 0;
+	case hwmon_fan_fault:
+		*val = fan_failed(dev, channel);
+		return 0;
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static int gxp_pwm_read(struct device *dev, u32 attr, int channel, long *val)
+{
+	struct gxp_fan_ctrl_drvdata *drvdata = dev_get_drvdata(dev);
+	u32 reg;
+
+	/*
+	 * Check the power status of the platform. If the platform is off
+	 * the value reported for the PWM will be incorrect. In this case
+	 * report a PWM of zero.
+	 */
+
+	reg = readl(drvdata->fn2 + OFS_SEVSTAT);
+
+	if (reg & BIT(POWER_BIT))
+		*val = fan_installed(dev, channel) ? readb(drvdata->base + channel) : 0;
+	else
+		*val = 0;
+
+	return 0;
+}
+
+static int gxp_fan_ctrl_read(struct device *dev, enum hwmon_sensor_types type,
+			     u32 attr, int channel, long *val)
+{
+	switch (type) {
+	case hwmon_fan:
+		return gxp_fan_read(dev, attr, channel, val);
+	case hwmon_pwm:
+		return gxp_pwm_read(dev, attr, channel, val);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static umode_t gxp_fan_ctrl_is_visible(const void *_data,
+				       enum hwmon_sensor_types type,
+				       u32 attr, int channel)
+{
+	umode_t mode = 0;
+
+	switch (type) {
+	case hwmon_fan:
+		switch (attr) {
+		case hwmon_fan_enable:
+		case hwmon_fan_fault:
+			mode = 0444;
+			break;
+		default:
+			break;
+		}
+		break;
+	case hwmon_pwm:
+		switch (attr) {
+		case hwmon_pwm_input:
+			mode = 0644;
+			break;
+		default:
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+
+	return mode;
+}
+
+static const struct hwmon_ops gxp_fan_ctrl_ops = {
+	.is_visible = gxp_fan_ctrl_is_visible,
+	.read = gxp_fan_ctrl_read,
+	.write = gxp_fan_ctrl_write,
+};
+
+static const struct hwmon_channel_info *gxp_fan_ctrl_info[] = {
+	HWMON_CHANNEL_INFO(fan,
+			   HWMON_F_FAULT | HWMON_F_ENABLE,
+			   HWMON_F_FAULT | HWMON_F_ENABLE,
+			   HWMON_F_FAULT | HWMON_F_ENABLE,
+			   HWMON_F_FAULT | HWMON_F_ENABLE,
+			   HWMON_F_FAULT | HWMON_F_ENABLE,
+			   HWMON_F_FAULT | HWMON_F_ENABLE,
+			   HWMON_F_FAULT | HWMON_F_ENABLE,
+			   HWMON_F_FAULT | HWMON_F_ENABLE),
+	HWMON_CHANNEL_INFO(pwm,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT),
+	NULL
+};
+
+static const struct hwmon_chip_info gxp_fan_ctrl_chip_info = {
+	.ops = &gxp_fan_ctrl_ops,
+	.info = gxp_fan_ctrl_info,
+
+};
+
+static int gxp_fan_ctrl_probe(struct platform_device *pdev)
+{
+	struct gxp_fan_ctrl_drvdata *drvdata;
+	struct resource *res;
+	struct device *dev = &pdev->dev;
+	struct device *hwmon_dev;
+
+	drvdata = devm_kzalloc(dev, sizeof(struct gxp_fan_ctrl_drvdata),
+			       GFP_KERNEL);
+	if (!drvdata)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	drvdata->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(drvdata->base))
+		return dev_err_probe(dev, PTR_ERR(drvdata->base),
+				     "failed to map base\n");
+
+	drvdata->plreg = devm_platform_ioremap_resource_byname(pdev,
+							       "pl");
+	if (IS_ERR(drvdata->plreg))
+		return dev_err_probe(dev, PTR_ERR(drvdata->plreg),
+				     "failed to map plreg\n");
+
+	drvdata->fn2 = devm_platform_ioremap_resource_byname(pdev,
+							     "fn2");
+	if (IS_ERR(drvdata->fn2))
+		return dev_err_probe(dev, PTR_ERR(drvdata->fn2),
+				     "failed to map fn2\n");
+
+	hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
+							 "hpe_gxp_fan_ctrl",
+							 drvdata,
+							 &gxp_fan_ctrl_chip_info,
+							 NULL);
+
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct of_device_id gxp_fan_ctrl_of_match[] = {
+	{ .compatible = "hpe,gxp-fan-ctrl", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, gxp_fan_ctrl_of_match);
+
+static struct platform_driver gxp_fan_ctrl_driver = {
+	.probe		= gxp_fan_ctrl_probe,
+	.driver = {
+		.name	= "gxp-fan-ctrl",
+		.of_match_table = gxp_fan_ctrl_of_match,
+	},
+};
+module_platform_driver(gxp_fan_ctrl_driver);
+
+MODULE_AUTHOR("Nick Hawkins <nick.hawkins@hpe.com>");
+MODULE_DESCRIPTION("HPE GXP fan controller");
+MODULE_LICENSE("GPL");