Linux 7.0.2 add ws2812b

Documentation/devicetree/bindings/leds/worldsemi,ws2812b.yaml

@@ -0,0 +1,116 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/worldsemi,ws2812b.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: WS2812B LEDs driven using SPI
+
+maintainers:
+  - Chuanhong Guo <gch981213@gmail.com>
+
+description: |
+  WorldSemi WS2812B is a individually addressable LED chip that can be chained
+  together and controlled individually using a single wire.
+  This binding describes a chain of WS2812B LEDs connected to the SPI MOSI pin.
+  Typical setups includes connecting the data pin of the LED chain to MOSI as
+  the only device or using CS and MOSI with a tri-state voltage-level shifter
+  for the data pin.
+  The SPI frequency needs to be 2.105MHz~2.85MHz for the timing to be correct
+  and the controller needs to send all the bytes continuously.
+
+allOf:
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+
+properties:
+  compatible:
+    const: worldsemi,ws2812b
+
+  reg:
+    maxItems: 1
+
+  spi-max-frequency:
+    minimum: 2105000
+    maximum: 2850000
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 0
+
+patternProperties:
+  "^multi-led@[0-9a-f]+$":
+    type: object
+    $ref: leds-class-multicolor.yaml#
+    unevaluatedProperties: false
+
+    properties:
+      color-index:
+        description: |
+          A 3-item array specifying color of each components in this LED. It
+          should be one of the LED_COLOR_ID_* prefixed definitions from the
+          header include/dt-bindings/leds/common.h. Defaults to
+          <LED_COLOR_ID_GREEN LED_COLOR_ID_RED LED_COLOR_ID_BLUE>
+          if unspecified.
+        $ref: /schemas/types.yaml#/definitions/uint32-array
+        maxItems: 3
+
+      reg:
+        description: |
+          Which LED this node represents. The reg of the first LED on the chain
+          is 0.
+        maxItems: 1
+
+    required:
+      - reg
+      - color
+      - function
+
+required:
+  - compatible
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/leds/common.h>
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        led-controller@0 {
+            compatible = "worldsemi,ws2812b";
+            reg = <0>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+            spi-max-frequency = <2850000>;
+            multi-led@0 {
+                reg = <0>;
+                color-index = <LED_COLOR_ID_RED LED_COLOR_ID_GREEN LED_COLOR_ID_BLUE>;
+                color = <LED_COLOR_ID_RGB>;
+                function = LED_FUNCTION_STATUS;
+                function-enumerator = <0>;
+            };
+            multi-led@1 {
+                reg = <1>;
+                color = <LED_COLOR_ID_RGB>;
+                function = LED_FUNCTION_STATUS;
+                function-enumerator = <1>;
+            };
+            multi-led@2 {
+                reg = <2>;
+                color = <LED_COLOR_ID_RGB>;
+                function = LED_FUNCTION_STATUS;
+                function-enumerator = <2>;
+            };
+            multi-led@3 {
+                reg = <3>;
+                color = <LED_COLOR_ID_RGB>;
+                function = LED_FUNCTION_STATUS;
+                function-enumerator = <3>;
+            };
+        };
+    };
+
+...

Documentation/devicetree/bindings/vendor-prefixes.yaml

@@ -1845,6 +1845,8 @@ patternProperties:
     description: Wondermedia Technologies, Inc.
   "^wobo,.*":
     description: Wobo
+  "^worldsemi,.*":
+    description: WorldSemi Co., Limited
   "^wolfvision,.*":
     description: WolfVision GmbH
   "^x-powers,.*":

drivers/leds/rgb/Kconfig

@@ -88,4 +88,15 @@ config LEDS_MT6370_RGB
 	  This driver can also be built as a module. If so, the module
 	  will be called "leds-mt6370-rgb".
 
+config LEDS_WS2812B
+	tristate "SPI driven WS2812B RGB LED support"
+	depends on OF
+	depends on SPI
+	help
+	  This option enables support for driving daisy-chained WS2812B RGB
+	  LED chips using SPI bus. This driver simulates the single-wire
+	  protocol by sending bits over the SPI MOSI pin. For this to work,
+	  the SPI frequency should be 2.105MHz~2.85MHz and the controller
+	  needs to transfer all the bytes continuously.
+
 endif # LEDS_CLASS_MULTICOLOR

drivers/leds/rgb/Makefile

@@ -7,3 +7,4 @@ obj-$(CONFIG_LEDS_NCP5623)		+= leds-ncp5623.o
 obj-$(CONFIG_LEDS_PWM_MULTICOLOR)	+= leds-pwm-multicolor.o
 obj-$(CONFIG_LEDS_QCOM_LPG)		+= leds-qcom-lpg.o
 obj-$(CONFIG_LEDS_MT6370_RGB)		+= leds-mt6370-rgb.o
+obj-$(CONFIG_LEDS_WS2812B)		+= leds-ws2812b.o

drivers/leds/rgb/leds-ws2812b.c

@@ -0,0 +1,231 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * WorldSemi WS2812B individually-addressable LED driver using SPI
+ *
+ * Copyright 2022 Chuanhong Guo <gch981213@gmail.com>
+ *
+ * This driver simulates WS2812B protocol using SPI MOSI pin. A one pulse
+ * is transferred as 3'b110 and a zero pulse is 3'b100. For this driver to
+ * work properly, the SPI frequency should be 2.105MHz~2.85MHz and it needs
+ * to transfer all the bytes continuously.
+ */
+
+#include <linux/led-class-multicolor.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/property.h>
+#include <linux/spi/spi.h>
+#include <linux/mutex.h>
+
+#define WS2812B_BYTES_PER_COLOR 3
+#define WS2812B_NUM_COLORS 3
+/* A continuous 0 for 50us+ as the 'reset' signal */
+#define WS2812B_RESET_LEN 18
+
+struct ws2812b_led {
+	struct led_classdev_mc mc_cdev;
+	struct mc_subled subled[WS2812B_NUM_COLORS];
+	int cascade;
+};
+
+struct ws2812b_priv {
+	struct led_classdev ldev;
+	struct spi_device *spi;
+	struct mutex mutex;
+	int num_leds;
+	size_t data_len;
+	u8 *data_buf;
+	struct ws2812b_led leds[];
+};
+
+/**
+ * ws2812b_set_byte - convert a byte of data to 3-byte SPI data for pulses
+ * @priv: pointer to the private data structure
+ * @offset: offset of the target byte in the data stream
+ * @val: 1-byte data to be set
+ *
+ * WS2812B receives a stream of bytes from DI, takes the first 3 byte as LED
+ * brightness and pases the rest to the next LED through the DO pin.
+ * This function assembles a single byte of data to the LED:
+ * A bit is represented with a pulse of specific length. A long pulse is a 1
+ * and a short pulse is a 0.
+ * SPI transfers data continuously, MSB first. We can send 3'b100 to create a
+ * 0 pulse and 3'b110 for a 1 pulse. In this way, a byte of data takes up 3
+ * bytes in a SPI transfer:
+ *  1x0 1x0 1x0 1x0 1x0 1x0 1x0 1x0
+ * Let's rearrange it in 8 bits:
+ *  1x01x01x 01x01x01 x01x01x0
+ * The higher 3 bits, middle 2 bits and lower 3 bits are represented with the
+ * 1st, 2nd and 3rd byte in the SPI transfer respectively.
+ * There are only 8 combinations for 3 bits and 4 for 2 bits, so we can create
+ * a lookup table for the 3 bytes.
+ * e.g. For 0x6b -> 2'b01101011:
+ *  Bit 7-5: 3'b011 -> 10011011 -> 0x9b
+ *  Bit 4-3: 2'b01  -> 01001101 -> 0x4d
+ *  Bit 2-0: 3'b011 -> 00110110 -> 0x36
+ */
+static void ws2812b_set_byte(struct ws2812b_priv *priv, size_t offset, u8 val)
+{
+	/* The lookup table for Bit 7-5 4-3 2-0 */
+	const u8 h3b[] = { 0x92, 0x93, 0x9a, 0x9b, 0xd2, 0xd3, 0xda, 0xdb };
+	const u8 m2b[] = { 0x49, 0x4d, 0x69, 0x6d };
+	const u8 l3b[] = { 0x24, 0x26, 0x34, 0x36, 0xa4, 0xa6, 0xb4, 0xb6 };
+	u8 *p = priv->data_buf + WS2812B_RESET_LEN + (offset * WS2812B_BYTES_PER_COLOR);
+
+	p[0] = h3b[val >> 5]; /* Bit 7-5 */
+	p[1] = m2b[(val >> 3) & 0x3]; /* Bit 4-3 */
+	p[2] = l3b[val & 0x7]; /* Bit 2-0 */
+}
+
+static int ws2812b_set(struct led_classdev *cdev,
+		       enum led_brightness brightness)
+{
+	struct led_classdev_mc *mc_cdev = lcdev_to_mccdev(cdev);
+	struct ws2812b_led *led =
+		container_of(mc_cdev, struct ws2812b_led, mc_cdev);
+	struct ws2812b_priv *priv = dev_get_drvdata(cdev->dev->parent);
+	int ret;
+	int i;
+
+	led_mc_calc_color_components(mc_cdev, brightness);
+
+	mutex_lock(&priv->mutex);
+	for (i = 0; i < WS2812B_NUM_COLORS; i++)
+		ws2812b_set_byte(priv, led->cascade * WS2812B_NUM_COLORS + i,
+				 led->subled[i].brightness);
+	ret = spi_write(priv->spi, priv->data_buf, priv->data_len);
+	mutex_unlock(&priv->mutex);
+
+	return ret;
+}
+
+static int ws2812b_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	int cur_led = 0;
+	struct ws2812b_priv *priv;
+	struct fwnode_handle *led_node;
+	int num_leds, i, cnt, ret;
+
+	num_leds = device_get_child_node_count(dev);
+
+	priv = devm_kzalloc(dev, struct_size(priv, leds, num_leds), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+	priv->data_len =
+		num_leds * WS2812B_BYTES_PER_COLOR * WS2812B_NUM_COLORS +
+		WS2812B_RESET_LEN;
+	priv->data_buf = kzalloc(priv->data_len, GFP_KERNEL);
+	if (!priv->data_buf)
+		return -ENOMEM;
+
+	for (i = 0; i < num_leds * WS2812B_NUM_COLORS; i++)
+		ws2812b_set_byte(priv, i, 0);
+
+	mutex_init(&priv->mutex);
+	priv->num_leds = num_leds;
+	priv->spi = spi;
+
+	device_for_each_child_node(dev, led_node) {
+		struct led_init_data init_data = {
+			.fwnode = led_node,
+		};
+		/* WS2812B LEDs usually come with GRB color */
+		u32 color_idx[WS2812B_NUM_COLORS] = {
+			LED_COLOR_ID_GREEN,
+			LED_COLOR_ID_RED,
+			LED_COLOR_ID_BLUE,
+		};
+		u32 cascade;
+
+		ret = fwnode_property_read_u32(led_node, "reg", &cascade);
+		if (ret) {
+			dev_err(dev, "failed to obtain numerical LED index for %s",
+				fwnode_get_name(led_node));
+			goto ERR_UNREG_LEDS;
+		}
+		if (cascade >= num_leds) {
+			dev_err(dev, "LED index of %s is larger than the number of LEDs.",
+				fwnode_get_name(led_node));
+			ret = -EINVAL;
+			goto ERR_UNREG_LEDS;
+		}
+
+		cnt = fwnode_property_count_u32(led_node, "color-index");
+		if (cnt > 0 && cnt <= WS2812B_NUM_COLORS)
+			fwnode_property_read_u32_array(led_node, "color-index",
+						       color_idx, (size_t)cnt);
+
+		priv->leds[cur_led].mc_cdev.subled_info =
+			priv->leds[cur_led].subled;
+		priv->leds[cur_led].mc_cdev.num_colors = WS2812B_NUM_COLORS;
+		priv->leds[cur_led].mc_cdev.led_cdev.max_brightness = 255;
+		priv->leds[cur_led].mc_cdev.led_cdev.brightness_set_blocking = ws2812b_set;
+
+		for (i = 0; i < WS2812B_NUM_COLORS; i++) {
+			priv->leds[cur_led].subled[i].color_index = color_idx[i];
+			priv->leds[cur_led].subled[i].intensity = 255;
+		}
+
+		priv->leds[cur_led].cascade = cascade;
+
+		ret = led_classdev_multicolor_register_ext(
+			dev, &priv->leds[cur_led].mc_cdev, &init_data);
+		if (ret) {
+			dev_err(dev, "registration of %s failed.",
+				fwnode_get_name(led_node));
+			goto ERR_UNREG_LEDS;
+		}
+		cur_led++;
+	}
+
+	spi_set_drvdata(spi, priv);
+
+	return 0;
+ERR_UNREG_LEDS:
+	for (; cur_led >= 0; cur_led--)
+		led_classdev_multicolor_unregister(&priv->leds[cur_led].mc_cdev);
+	mutex_destroy(&priv->mutex);
+	kfree(priv->data_buf);
+	return ret;
+}
+
+static void ws2812b_remove(struct spi_device *spi)
+{
+	struct ws2812b_priv *priv = spi_get_drvdata(spi);
+	int cur_led;
+
+	for (cur_led = priv->num_leds - 1; cur_led >= 0; cur_led--)
+		led_classdev_multicolor_unregister(&priv->leds[cur_led].mc_cdev);
+	kfree(priv->data_buf);
+	mutex_destroy(&priv->mutex);
+}
+
+static const struct spi_device_id ws2812b_spi_ids[] = {
+	{ "ws2812b" },
+	{},
+};
+MODULE_DEVICE_TABLE(spi, ws2812b_spi_ids);
+
+static const struct of_device_id ws2812b_dt_ids[] = {
+	{ .compatible = "worldsemi,ws2812b" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, ws2812b_dt_ids);
+
+static struct spi_driver ws2812b_driver = {
+	.probe		= ws2812b_probe,
+	.remove		= ws2812b_remove,
+	.id_table	= ws2812b_spi_ids,
+	.driver = {
+		.name		= KBUILD_MODNAME,
+		.of_match_table	= ws2812b_dt_ids,
+	},
+};
+
+module_spi_driver(ws2812b_driver);
+
+MODULE_AUTHOR("Chuanhong Guo <gch981213@gmail.com>");
+MODULE_DESCRIPTION("WS2812B LED driver using SPI");
+MODULE_LICENSE("GPL");