Add rpi-poe-fan driver

Signed-off-by: Serge Schneider <serge@raspberrypi.org>

PoE HAT driver cleanup

* Fix undeclared variable in rpi_poe_fan_suspend
* Add SPDX-License-Identifier
* Expand PoE acronym in Kconfig help
* Give clearer error message on of_property_count_u32_elems fail
* Add documentation
* Add vendor to of_device_id compatible string.
* Rename m_data_s struct to fw_data_s
* Fix typos

Fixes: #2665

Signed-off-by: Serge Schneider <serge@raspberrypi.org>

Documentation/devicetree/bindings/hwmon/rpi-poe-fan.txt

@@ -0,0 +1,55 @@
+Bindings for the Raspberry Pi PoE HAT fan
+
+Required properties:
+- compatible	: "raspberrypi,rpi-poe-fan"
+- firmware	: Reference to the RPi firmware device node
+- pwms		: the PWM that is used to control the PWM fan
+- cooling-levels      : PWM duty cycle values in a range from 0 to 255
+			which correspond to thermal cooling states
+
+Example:
+	fan0: rpi-poe-fan@0 {
+		compatible = "raspberrypi,rpi-poe-fan";
+		firmware = <&firmware>;
+		cooling-min-state = <0>;
+		cooling-max-state = <3>;
+		#cooling-cells = <2>;
+		cooling-levels = <0 50 150 255>;
+		status = "okay";
+	};
+
+	thermal-zones {
+		cpu_thermal: cpu-thermal {
+			trips {
+				threshold: trip-point@0 {
+					temperature = <45000>;
+					hysteresis = <5000>;
+					type = "active";
+				};
+				target: trip-point@1 {
+					temperature = <50000>;
+					hysteresis = <2000>;
+					type = "active";
+				};
+				cpu_hot: cpu_hot@0 {
+					temperature = <55000>;
+					hysteresis = <2000>;
+					type = "active";
+				};
+			};
+			cooling-maps {
+				map0 {
+					trip = <&threshold>;
+					cooling-device = <&fan0 0 1>;
+				};
+				map1 {
+					trip = <&target>;
+					cooling-device = <&fan0 1 2>;
+				};
+				map2 {
+					trip = <&cpu_hot>;
+					cooling-device = <&fan0 2 3>;
+				};
+			};
+		};
+	};

Documentation/hwmon/rpi-poe-fan

@@ -0,0 +1,15 @@
+Kernel driver rpi-poe-fan
+=====================
+
+This driver enables the use of the Raspberry Pi PoE HAT fan.
+
+Author: Serge Schneider <serge@raspberrypi.org>
+
+Description
+-----------
+
+The driver implements a simple interface for driving the Raspberry Pi PoE
+(Power over Ethernet) HAT fan. The driver passes commands to the Raspberry Pi
+firmware through the mailbox property interface. The firmware then forwards
+the commands to the board over I2C on the ID_EEPROM pins. The driver exposes
+the fan to the user space through the hwmon sysfs interface.

drivers/hwmon/Kconfig

@@ -1346,6 +1346,17 @@ config SENSORS_RASPBERRYPI_HWMON
 	  This driver can also be built as a module. If so, the module
 	  will be called raspberrypi-hwmon.
 
+config SENSORS_RPI_POE_FAN
+	tristate "Raspberry Pi PoE HAT fan"
+	depends on RASPBERRYPI_FIRMWARE
+	depends on THERMAL || THERMAL=n
+	help
+	  If you say yes here you get support for Raspberry Pi PoE (Power over
+	  Ethernet) HAT fan.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called rpi-poe-fan.
+
 config SENSORS_SHT15
 	tristate "Sensiron humidity and temperature sensors. SHT15 and compat."
 	depends on GPIOLIB || COMPILE_TEST

drivers/hwmon/Makefile

@@ -145,6 +145,7 @@ obj-$(CONFIG_SENSORS_PCF8591)	+= pcf8591.o
 obj-$(CONFIG_SENSORS_POWR1220)  += powr1220.o
 obj-$(CONFIG_SENSORS_PWM_FAN)	+= pwm-fan.o
 obj-$(CONFIG_SENSORS_RASPBERRYPI_HWMON)	+= raspberrypi-hwmon.o
+obj-$(CONFIG_SENSORS_RPI_POE_FAN)	+= rpi-poe-fan.o
 obj-$(CONFIG_SENSORS_S3C)	+= s3c-hwmon.o
 obj-$(CONFIG_SENSORS_SCH56XX_COMMON)+= sch56xx-common.o
 obj-$(CONFIG_SENSORS_SCH5627)	+= sch5627.o

drivers/hwmon/rpi-poe-fan.c

@@ -0,0 +1,436 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * rpi-poe-fan.c - Hwmon driver for Raspberry Pi PoE HAT fan.
+ *
+ * Copyright (C) 2018 Raspberry Pi (Trading) Ltd.
+ * Based on pwm-fan.c by Kamil Debski <k.debski@samsung.com>
+ *
+ * Author: Serge Schneider <serge@raspberrypi.org>
+ */
+
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/notifier.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/sysfs.h>
+#include <linux/thermal.h>
+#include <soc/bcm2835/raspberrypi-firmware.h>
+
+#define MAX_PWM 255
+
+#define POE_CUR_PWM 0x0
+#define POE_DEF_PWM 0x1
+
+struct rpi_poe_fan_ctx {
+	struct mutex lock;
+	struct rpi_firmware *fw;
+	unsigned int pwm_value;
+	unsigned int def_pwm_value;
+	unsigned int rpi_poe_fan_state;
+	unsigned int rpi_poe_fan_max_state;
+	unsigned int *rpi_poe_fan_cooling_levels;
+	struct thermal_cooling_device *cdev;
+	struct notifier_block nb;
+};
+
+struct fw_tag_data_s{
+	u32 reg;
+	u32 val;
+	u32 ret;
+};
+
+static int write_reg(struct rpi_firmware *fw, u32 reg, u32 *val){
+	struct fw_tag_data_s fw_tag_data = {
+		.reg = reg,
+		.val = *val
+	};
+	int ret;
+	ret = rpi_firmware_property(fw, RPI_FIRMWARE_SET_POE_HAT_VAL,
+				    &fw_tag_data, sizeof(fw_tag_data));
+	if (ret) {
+		return ret;
+	} else if (fw_tag_data.ret) {
+		return -EIO;
+	}
+	return 0;
+}
+
+static int read_reg(struct rpi_firmware *fw, u32 reg, u32 *val){
+	struct fw_tag_data_s fw_tag_data = {
+		.reg = reg,
+	};
+	int ret;
+	ret = rpi_firmware_property(fw, RPI_FIRMWARE_GET_POE_HAT_VAL,
+				    &fw_tag_data, sizeof(fw_tag_data));
+	if (ret) {
+		return ret;
+	} else if (fw_tag_data.ret) {
+		return -EIO;
+	}
+	*val = fw_tag_data.val;
+	return 0;
+}
+
+static int rpi_poe_reboot(struct notifier_block *nb, unsigned long code,
+			  void *unused)
+{
+	struct rpi_poe_fan_ctx *ctx = container_of(nb, struct rpi_poe_fan_ctx,
+						   nb);
+
+	if (ctx->pwm_value != ctx->def_pwm_value)
+		write_reg(ctx->fw, POE_CUR_PWM, &ctx->def_pwm_value);
+
+	return NOTIFY_DONE;
+}
+
+static int  __set_pwm(struct rpi_poe_fan_ctx *ctx, u32 pwm)
+{
+	int ret = 0;
+
+	mutex_lock(&ctx->lock);
+	if (ctx->pwm_value == pwm)
+		goto exit_set_pwm_err;
+
+	ret = write_reg(ctx->fw, POE_CUR_PWM, &pwm);
+	if (!ret)
+		ctx->pwm_value = pwm;
+exit_set_pwm_err:
+	mutex_unlock(&ctx->lock);
+	return ret;
+}
+
+static int  __set_def_pwm(struct rpi_poe_fan_ctx *ctx, u32 def_pwm)
+{
+	int ret = 0;
+	mutex_lock(&ctx->lock);
+	if (ctx->def_pwm_value == def_pwm)
+		goto exit_set_def_pwm_err;
+
+	ret = write_reg(ctx->fw, POE_CUR_PWM, &def_pwm);
+	if (!ret)
+		ctx->def_pwm_value = def_pwm;
+exit_set_def_pwm_err:
+	mutex_unlock(&ctx->lock);
+	return ret;
+}
+
+static void rpi_poe_fan_update_state(struct rpi_poe_fan_ctx *ctx,
+				     unsigned long pwm)
+{
+	int i;
+
+	for (i = 0; i < ctx->rpi_poe_fan_max_state; ++i)
+		if (pwm < ctx->rpi_poe_fan_cooling_levels[i + 1])
+			break;
+
+	ctx->rpi_poe_fan_state = i;
+}
+
+static ssize_t set_pwm(struct device *dev, struct device_attribute *attr,
+		       const char *buf, size_t count)
+{
+	struct rpi_poe_fan_ctx *ctx = dev_get_drvdata(dev);
+	unsigned long pwm;
+	int ret;
+
+	if (kstrtoul(buf, 10, &pwm) || pwm > MAX_PWM)
+		return -EINVAL;
+
+	ret = __set_pwm(ctx, pwm);
+	if (ret)
+		return ret;
+
+	rpi_poe_fan_update_state(ctx, pwm);
+	return count;
+}
+
+static ssize_t set_def_pwm(struct device *dev, struct device_attribute *attr,
+			   const char *buf, size_t count)
+{
+	struct rpi_poe_fan_ctx *ctx = dev_get_drvdata(dev);
+	unsigned long def_pwm;
+	int ret;
+
+	if (kstrtoul(buf, 10, &def_pwm) || def_pwm > MAX_PWM)
+		return -EINVAL;
+
+	ret = __set_def_pwm(ctx, def_pwm);
+	if (ret)
+		return ret;
+	return count;
+}
+
+static ssize_t show_pwm(struct device *dev,
+			struct device_attribute *attr, char *buf)
+{
+	struct rpi_poe_fan_ctx *ctx = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%u\n", ctx->pwm_value);
+}
+
+static ssize_t show_def_pwm(struct device *dev,
+			struct device_attribute *attr, char *buf)
+{
+	struct rpi_poe_fan_ctx *ctx = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%u\n", ctx->def_pwm_value);
+}
+
+
+static SENSOR_DEVICE_ATTR(pwm1, 0644, show_pwm, set_pwm, 0);
+static SENSOR_DEVICE_ATTR(def_pwm1, 0644, show_def_pwm, set_def_pwm, 1);
+
+static struct attribute *rpi_poe_fan_attrs[] = {
+	&sensor_dev_attr_pwm1.dev_attr.attr,
+	&sensor_dev_attr_def_pwm1.dev_attr.attr,
+	NULL,
+};
+
+ATTRIBUTE_GROUPS(rpi_poe_fan);
+
+/* thermal cooling device callbacks */
+static int rpi_poe_fan_get_max_state(struct thermal_cooling_device *cdev,
+				     unsigned long *state)
+{
+	struct rpi_poe_fan_ctx *ctx = cdev->devdata;
+
+	if (!ctx)
+		return -EINVAL;
+
+	*state = ctx->rpi_poe_fan_max_state;
+
+	return 0;
+}
+
+static int rpi_poe_fan_get_cur_state(struct thermal_cooling_device *cdev,
+				     unsigned long *state)
+{
+	struct rpi_poe_fan_ctx *ctx = cdev->devdata;
+
+	if (!ctx)
+		return -EINVAL;
+
+	*state = ctx->rpi_poe_fan_state;
+
+	return 0;
+}
+
+static int rpi_poe_fan_set_cur_state(struct thermal_cooling_device *cdev,
+				     unsigned long state)
+{
+	struct rpi_poe_fan_ctx *ctx = cdev->devdata;
+	int ret;
+
+	if (!ctx || (state > ctx->rpi_poe_fan_max_state))
+		return -EINVAL;
+
+	if (state == ctx->rpi_poe_fan_state)
+		return 0;
+
+	ret = __set_pwm(ctx, ctx->rpi_poe_fan_cooling_levels[state]);
+	if (ret) {
+		dev_err(&cdev->device, "Cannot set pwm!\n");
+		return ret;
+	}
+
+	ctx->rpi_poe_fan_state = state;
+
+	return ret;
+}
+
+static const struct thermal_cooling_device_ops rpi_poe_fan_cooling_ops = {
+	.get_max_state = rpi_poe_fan_get_max_state,
+	.get_cur_state = rpi_poe_fan_get_cur_state,
+	.set_cur_state = rpi_poe_fan_set_cur_state,
+};
+
+static int rpi_poe_fan_of_get_cooling_data(struct device *dev,
+				       struct rpi_poe_fan_ctx *ctx)
+{
+	struct device_node *np = dev->of_node;
+	int num, i, ret;
+
+	if (!of_find_property(np, "cooling-levels", NULL))
+		return 0;
+
+	ret = of_property_count_u32_elems(np, "cooling-levels");
+	if (ret <= 0) {
+		dev_err(dev, "cooling-levels property missing or invalid: %d\n",
+			ret);
+		return ret ? : -EINVAL;
+	}
+
+	num = ret;
+	ctx->rpi_poe_fan_cooling_levels = devm_kzalloc(dev, num * sizeof(u32),
+						   GFP_KERNEL);
+	if (!ctx->rpi_poe_fan_cooling_levels)
+		return -ENOMEM;
+
+	ret = of_property_read_u32_array(np, "cooling-levels",
+					 ctx->rpi_poe_fan_cooling_levels, num);
+	if (ret) {
+		dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
+		return ret;
+	}
+
+	for (i = 0; i < num; i++) {
+		if (ctx->rpi_poe_fan_cooling_levels[i] > MAX_PWM) {
+			dev_err(dev, "PWM fan state[%d]:%d > %d\n", i,
+				ctx->rpi_poe_fan_cooling_levels[i], MAX_PWM);
+			return -EINVAL;
+		}
+	}
+
+	ctx->rpi_poe_fan_max_state = num - 1;
+
+	return 0;
+}
+
+static int rpi_poe_fan_probe(struct platform_device *pdev)
+{
+	struct thermal_cooling_device *cdev;
+	struct rpi_poe_fan_ctx *ctx;
+	struct device *hwmon;
+	struct device_node *np = pdev->dev.of_node;
+	struct device_node *fw_node;
+	int ret;
+
+	fw_node = of_parse_phandle(np, "firmware", 0);
+	if (!fw_node) {
+		dev_err(&pdev->dev, "Missing firmware node\n");
+		return -ENOENT;
+	}
+
+	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
+
+	mutex_init(&ctx->lock);
+
+	ctx->fw = rpi_firmware_get(fw_node);
+	if (!ctx->fw)
+		return -EPROBE_DEFER;
+
+	platform_set_drvdata(pdev, ctx);
+
+	ctx->nb.notifier_call = rpi_poe_reboot;
+	ret = register_reboot_notifier(&ctx->nb);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to register reboot notifier: %i\n",
+			ret);
+		return ret;
+	}
+	ret = read_reg(ctx->fw, POE_DEF_PWM, &ctx->def_pwm_value);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to get default PWM value: %i\n",
+			ret);
+		goto err;
+	}
+	ret = read_reg(ctx->fw, POE_CUR_PWM, &ctx->pwm_value);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to get current PWM value: %i\n",
+			ret);
+		goto err;
+	}
+
+	hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "rpipoefan",
+						       ctx, rpi_poe_fan_groups);
+	if (IS_ERR(hwmon)) {
+		dev_err(&pdev->dev, "Failed to register hwmon device\n");
+		ret = PTR_ERR(hwmon);
+		goto err;
+	}
+
+	ret = rpi_poe_fan_of_get_cooling_data(&pdev->dev, ctx);
+	if (ret)
+		return ret;
+
+	rpi_poe_fan_update_state(ctx, ctx->pwm_value);
+	if (!IS_ENABLED(CONFIG_THERMAL))
+		return 0;
+
+	cdev = thermal_of_cooling_device_register(np,
+						  "rpi-poe-fan", ctx,
+						  &rpi_poe_fan_cooling_ops);
+	if (IS_ERR(cdev)) {
+		dev_err(&pdev->dev,
+			"Failed to register rpi-poe-fan as cooling device");
+		ret = PTR_ERR(cdev);
+		goto err;
+	}
+	ctx->cdev = cdev;
+	thermal_cdev_update(cdev);
+
+	return 0;
+err:
+	unregister_reboot_notifier(&ctx->nb);
+	return ret;
+}
+
+static int rpi_poe_fan_remove(struct platform_device *pdev)
+{
+	struct rpi_poe_fan_ctx *ctx = platform_get_drvdata(pdev);
+	u32 value = ctx->def_pwm_value;
+
+	unregister_reboot_notifier(&ctx->nb);
+	thermal_cooling_device_unregister(ctx->cdev);
+	if (ctx->pwm_value != value) {
+		write_reg(ctx->fw, POE_CUR_PWM, &value);
+	}
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int rpi_poe_fan_suspend(struct device *dev)
+{
+	struct rpi_poe_fan_ctx *ctx = dev_get_drvdata(dev);
+	u32 value = 0;
+	int ret = 0;
+
+	if (ctx->pwm_value != value)
+		ret = write_reg(ctx->fw, POE_CUR_PWM, &value);
+	return ret;
+}
+
+static int rpi_poe_fan_resume(struct device *dev)
+{
+	struct rpi_poe_fan_ctx *ctx = dev_get_drvdata(dev);
+	u32 value = ctx->pwm_value;
+	int ret = 0;
+
+	if (value != 0)
+		ret = write_reg(ctx->fw, POE_CUR_PWM, &value);
+
+	return ret;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(rpi_poe_fan_pm, rpi_poe_fan_suspend,
+			 rpi_poe_fan_resume);
+
+static const struct of_device_id of_rpi_poe_fan_match[] = {
+	{ .compatible = "raspberrypi,rpi-poe-fan", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, of_rpi_poe_fan_match);
+
+static struct platform_driver rpi_poe_fan_driver = {
+	.probe		= rpi_poe_fan_probe,
+	.remove		= rpi_poe_fan_remove,
+	.driver	= {
+		.name		= "rpi-poe-fan",
+		.pm		= &rpi_poe_fan_pm,
+		.of_match_table	= of_rpi_poe_fan_match,
+	},
+};
+
+module_platform_driver(rpi_poe_fan_driver);
+
+MODULE_AUTHOR("Serge Schneider <serge@raspberrypi.org>");
+MODULE_ALIAS("platform:rpi-poe-fan");
+MODULE_DESCRIPTION("Raspberry Pi PoE HAT fan driver");
+MODULE_LICENSE("GPL");