leds: add driver for support Mellanox regmap LEDs for BMC and x86 platform

Driver obtains LED devices according to system configuration and creates
devices in form: "devicename:color:function", like
The full path is to be:
/sys/class/leds/mlxreg\:status\:amber/brightness
After timer trigger activation:
echo timer > /sys/class/leds/mlxreg\:status\:amber/trigger
Attributes for LED blinking will appaer in sysfs infrastructure:
/sys/class/leds/mlxreg\:status\:amber/delay_off
/sys/class/leds/mlxreg\:status\:amber/delay_on

LED setting is controlled through the on-board programmable devices,
which exports its register map. This device could be attached to any
bus type, for which register mapping is supported.

Signed-off-by: Vadim Pasternak <vadimp@mellanox.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>

MAINTAINERS

@@ -9003,6 +9003,7 @@ M:	Vadim Pasternak <vadimp@mellanox.com>
 L:	linux-leds@vger.kernel.org
 S:	Supported
 F:	drivers/leds/leds-mlxcpld.c
+F:	drivers/leds/leds-mlxreg.c
 F:	Documentation/leds/leds-mlxcpld.txt
 
 MELLANOX PLATFORM DRIVER

drivers/leds/Kconfig

@@ -694,6 +694,15 @@ config LEDS_MLXCPLD
 	  This option enables support for the LEDs on the Mellanox
 	  boards. Say Y to enable these.
 
+config LEDS_MLXREG
+	tristate "LED support for the Mellanox switches management control"
+	depends on LEDS_CLASS
+	help
+	  This option enables support for the LEDs on the Mellanox Ethernet and
+	  InfiniBand switches. The driver can be activated by the platform device
+	  device add call. Say Y to enable these. To compile this driver as a
+	  module, choose 'M' here: the module will be called leds-mlxreg.
+
 config LEDS_USER
 	tristate "Userspace LED support"
 	depends on LEDS_CLASS

drivers/leds/Makefile

@@ -72,6 +72,7 @@ obj-$(CONFIG_LEDS_IS31FL319X)		+= leds-is31fl319x.o
 obj-$(CONFIG_LEDS_IS31FL32XX)		+= leds-is31fl32xx.o
 obj-$(CONFIG_LEDS_PM8058)		+= leds-pm8058.o
 obj-$(CONFIG_LEDS_MLXCPLD)		+= leds-mlxcpld.o
+obj-$(CONFIG_LEDS_MLXREG)		+= leds-mlxreg.o
 obj-$(CONFIG_LEDS_NIC78BX)		+= leds-nic78bx.o
 obj-$(CONFIG_LEDS_MT6323)		+= leds-mt6323.o
 obj-$(CONFIG_LEDS_LM3692X)		+= leds-lm3692x.o

drivers/leds/leds-mlxreg.c

@@ -0,0 +1,281 @@
+// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
+//
+// Copyright (c) 2018 Mellanox Technologies. All rights reserved.
+// Copyright (c) 2018 Vadim Pasternak <vadimp@mellanox.com>
+
+#include <linux/bitops.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_data/mlxreg.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+/* Codes for LEDs. */
+#define MLXREG_LED_OFFSET_BLINK_3HZ	0x01 /* Offset from solid: 3Hz blink */
+#define MLXREG_LED_OFFSET_BLINK_6HZ	0x02 /* Offset from solid: 6Hz blink */
+#define MLXREG_LED_IS_OFF		0x00 /* Off */
+#define MLXREG_LED_RED_SOLID		0x05 /* Solid red */
+#define MLXREG_LED_GREEN_SOLID		0x0D /* Solid green */
+#define MLXREG_LED_AMBER_SOLID		0x09 /* Solid amber */
+#define MLXREG_LED_BLINK_3HZ		167 /* ~167 msec off/on - HW support */
+#define MLXREG_LED_BLINK_6HZ		83 /* ~83 msec off/on - HW support */
+
+/**
+ * struct mlxreg_led_data - led control data:
+ *
+ * @data: led configuration data;
+ * @led_classdev: led class data;
+ * @base_color: base led color (other colors have constant offset from base);
+ * @led_data: led data;
+ * @data_parent: pointer to private device control data of parent;
+ */
+struct mlxreg_led_data {
+	struct mlxreg_core_data *data;
+	struct led_classdev led_cdev;
+	u8 base_color;
+	void *data_parent;
+	char led_cdev_name[MLXREG_CORE_LABEL_MAX_SIZE];
+};
+
+#define cdev_to_priv(c) container_of(c, struct mlxreg_led_data, led_cdev)
+
+/**
+ * struct mlxreg_led_priv_data - platform private data:
+ *
+ * @pdev: platform device;
+ * @pdata: platform data;
+ * @access_lock: mutex for attribute IO access;
+ */
+struct mlxreg_led_priv_data {
+	struct platform_device *pdev;
+	struct mlxreg_core_platform_data *pdata;
+	struct mutex access_lock; /* protect IO operations */
+};
+
+static int
+mlxreg_led_store_hw(struct mlxreg_led_data *led_data, u8 vset)
+{
+	struct mlxreg_led_priv_data *priv = led_data->data_parent;
+	struct mlxreg_core_platform_data *led_pdata = priv->pdata;
+	struct mlxreg_core_data *data = led_data->data;
+	u32 regval;
+	u32 nib;
+	int ret;
+
+	/*
+	 * Each LED is controlled through low or high nibble of the relevant
+	 * register byte. Register offset is specified by off parameter.
+	 * Parameter vset provides color code: 0x0 for off, 0x5 for solid red,
+	 * 0x6 for 3Hz blink red, 0xd for solid green, 0xe for 3Hz blink
+	 * green.
+	 * Parameter mask specifies which nibble is used for specific LED: mask
+	 * 0xf0 - lower nibble is to be used (bits from 0 to 3), mask 0x0f -
+	 * higher nibble (bits from 4 to 7).
+	 */
+	mutex_lock(&priv->access_lock);
+
+	ret = regmap_read(led_pdata->regmap, data->reg, &regval);
+	if (ret)
+		goto access_error;
+
+	nib = (ror32(data->mask, data->bit) == 0xf0) ? rol32(vset, data->bit) :
+	      rol32(vset, data->bit + 4);
+	regval = (regval & data->mask) | nib;
+
+	ret = regmap_write(led_pdata->regmap, data->reg, regval);
+
+access_error:
+	mutex_unlock(&priv->access_lock);
+
+	return ret;
+}
+
+static enum led_brightness
+mlxreg_led_get_hw(struct mlxreg_led_data *led_data)
+{
+	struct mlxreg_led_priv_data *priv = led_data->data_parent;
+	struct mlxreg_core_platform_data *led_pdata = priv->pdata;
+	struct mlxreg_core_data *data = led_data->data;
+	u32 regval;
+	int err;
+
+	/*
+	 * Each LED is controlled through low or high nibble of the relevant
+	 * register byte. Register offset is specified by off parameter.
+	 * Parameter vset provides color code: 0x0 for off, 0x5 for solid red,
+	 * 0x6 for 3Hz blink red, 0xd for solid green, 0xe for 3Hz blink
+	 * green.
+	 * Parameter mask specifies which nibble is used for specific LED: mask
+	 * 0xf0 - lower nibble is to be used (bits from 0 to 3), mask 0x0f -
+	 * higher nibble (bits from 4 to 7).
+	 */
+	err = regmap_read(led_pdata->regmap, data->reg, &regval);
+	if (err < 0) {
+		dev_warn(led_data->led_cdev.dev, "Failed to get current brightness, error: %d\n",
+			 err);
+		/* Assume the LED is OFF */
+		return LED_OFF;
+	}
+
+	regval = regval & ~data->mask;
+	regval = (ror32(data->mask, data->bit) == 0xf0) ? ror32(regval,
+		 data->bit) : ror32(regval, data->bit + 4);
+	if (regval >= led_data->base_color &&
+	    regval <= (led_data->base_color + MLXREG_LED_OFFSET_BLINK_6HZ))
+		return LED_FULL;
+
+	return LED_OFF;
+}
+
+static int
+mlxreg_led_brightness_set(struct led_classdev *cled, enum led_brightness value)
+{
+	struct mlxreg_led_data *led_data = cdev_to_priv(cled);
+
+	if (value)
+		return mlxreg_led_store_hw(led_data, led_data->base_color);
+	else
+		return mlxreg_led_store_hw(led_data, MLXREG_LED_IS_OFF);
+}
+
+static enum led_brightness
+mlxreg_led_brightness_get(struct led_classdev *cled)
+{
+	struct mlxreg_led_data *led_data = cdev_to_priv(cled);
+
+	return mlxreg_led_get_hw(led_data);
+}
+
+static int
+mlxreg_led_blink_set(struct led_classdev *cled, unsigned long *delay_on,
+		     unsigned long *delay_off)
+{
+	struct mlxreg_led_data *led_data = cdev_to_priv(cled);
+	int err;
+
+	/*
+	 * HW supports two types of blinking: full (6Hz) and half (3Hz).
+	 * For delay on/off zero LED is setting to solid color. For others
+	 * combination blinking is to be controlled by the software timer.
+	 */
+	if (!(*delay_on == 0 && *delay_off == 0) &&
+	    !(*delay_on == MLXREG_LED_BLINK_3HZ &&
+	      *delay_off == MLXREG_LED_BLINK_3HZ) &&
+	    !(*delay_on == MLXREG_LED_BLINK_6HZ &&
+	      *delay_off == MLXREG_LED_BLINK_6HZ))
+		return -EINVAL;
+
+	if (*delay_on == MLXREG_LED_BLINK_6HZ)
+		err = mlxreg_led_store_hw(led_data, led_data->base_color +
+					  MLXREG_LED_OFFSET_BLINK_6HZ);
+	else if (*delay_on == MLXREG_LED_BLINK_3HZ)
+		err = mlxreg_led_store_hw(led_data, led_data->base_color +
+					  MLXREG_LED_OFFSET_BLINK_3HZ);
+	else
+		err = mlxreg_led_store_hw(led_data, led_data->base_color);
+
+	return err;
+}
+
+static int mlxreg_led_config(struct mlxreg_led_priv_data *priv)
+{
+	struct mlxreg_core_platform_data *led_pdata = priv->pdata;
+	struct mlxreg_core_data *data = led_pdata->data;
+	struct mlxreg_led_data *led_data;
+	struct led_classdev *led_cdev;
+	enum led_brightness brightness;
+	int i;
+	int err;
+
+	for (i = 0; i < led_pdata->counter; i++, data++) {
+		led_data = devm_kzalloc(&priv->pdev->dev, sizeof(*led_data),
+					GFP_KERNEL);
+		if (!led_data)
+			return -ENOMEM;
+
+		led_cdev = &led_data->led_cdev;
+		led_data->data_parent = priv;
+		if (strstr(data->label, "red") ||
+		    strstr(data->label, "orange")) {
+			brightness = LED_OFF;
+			led_data->base_color = MLXREG_LED_RED_SOLID;
+		} else if (strstr(data->label, "amber")) {
+			brightness = LED_OFF;
+			led_data->base_color = MLXREG_LED_AMBER_SOLID;
+		} else {
+			brightness = LED_OFF;
+			led_data->base_color = MLXREG_LED_GREEN_SOLID;
+		}
+		sprintf(led_data->led_cdev_name, "%s:%s", "mlxreg",
+			data->label);
+		led_cdev->name = led_data->led_cdev_name;
+		led_cdev->brightness = brightness;
+		led_cdev->max_brightness = LED_ON;
+		led_cdev->brightness_set_blocking =
+						mlxreg_led_brightness_set;
+		led_cdev->brightness_get = mlxreg_led_brightness_get;
+		led_cdev->blink_set = mlxreg_led_blink_set;
+		led_cdev->flags = LED_CORE_SUSPENDRESUME;
+		led_data->data = data;
+		err = devm_led_classdev_register(&priv->pdev->dev, led_cdev);
+		if (err)
+			return err;
+
+		if (led_cdev->brightness)
+			mlxreg_led_brightness_set(led_cdev,
+						  led_cdev->brightness);
+		dev_info(led_cdev->dev, "label: %s, mask: 0x%02x, offset:0x%02x\n",
+			 data->label, data->mask, data->reg);
+	}
+
+	return 0;
+}
+
+static int mlxreg_led_probe(struct platform_device *pdev)
+{
+	struct mlxreg_core_platform_data *led_pdata;
+	struct mlxreg_led_priv_data *priv;
+
+	led_pdata = dev_get_platdata(&pdev->dev);
+	if (!led_pdata) {
+		dev_err(&pdev->dev, "Failed to get platform data.\n");
+		return -EINVAL;
+	}
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	mutex_init(&priv->access_lock);
+	priv->pdev = pdev;
+	priv->pdata = led_pdata;
+
+	return mlxreg_led_config(priv);
+}
+
+static int mlxreg_led_remove(struct platform_device *pdev)
+{
+	struct mlxreg_led_priv_data *priv = dev_get_drvdata(&pdev->dev);
+
+	mutex_destroy(&priv->access_lock);
+
+	return 0;
+}
+
+static struct platform_driver mlxreg_led_driver = {
+	.driver = {
+	    .name = "leds-mlxreg",
+	},
+	.probe = mlxreg_led_probe,
+	.remove = mlxreg_led_remove,
+};
+
+module_platform_driver(mlxreg_led_driver);
+
+MODULE_AUTHOR("Vadim Pasternak <vadimp@mellanox.com>");
+MODULE_DESCRIPTION("Mellanox LED regmap driver");
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_ALIAS("platform:leds-mlxreg");