openwrt/target/linux/bcm27xx/patches-6.6/950-1477-misc-Add-ws2812-pio-rp1-driver.patch

From d6d83ad3d9a3a594909a1ad1c82b735ab711cd12 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.com>
Date: Tue, 3 Dec 2024 16:09:30 +0000
Subject: [PATCH 1477/1482] misc: Add ws2812-pio-rp1 driver

ws2812-pio-rp1 is a PIO-based driver for WS2812 LEDS. It creates a
character device in /dev, the default name of which is /dev/leds<n>,
where <n> is the instance number. The number of LEDS should be set
in the DT overlay, as should whether it is RGB or RGBW, and the default
brightness.

Write data to the /dev/* entry in a 4 bytes-per-pixel format in RGBW
order:

  RR GG BB WW RR GG BB WW ...

The white values are ignored unless the rgbw flag is set for the device.

To change the brightness, write a single byte to offset 0, 255 being
full brightness and 0 being off.

Signed-off-by: Phil Elwell <phil@raspberrypi.com>
---
 drivers/misc/Kconfig          |  10 +
 drivers/misc/Makefile         |   1 +
 drivers/misc/ws2812-pio-rp1.c | 507 ++++++++++++++++++++++++++++++++++
 3 files changed, 518 insertions(+)
 create mode 100644 drivers/misc/ws2812-pio-rp1.c

--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -25,6 +25,16 @@ config RP1_PIO
 		Driver providing control of the Raspberry Pi PIO block, as found in
 		RP1.
 
+config WS2812_PIO_RP1
+	tristate "Raspberry Pi PIO-base WS2812 driver"
+	depends on RP1_PIO || COMPILE_TEST
+	default n
+	help
+		Driver for the WS2812 (NeoPixel) LEDs using the RP1 PIO hardware.
+		The driver creates a character device to which rgbw pixels may be
+		written. Single-byte writes to offset 0 set the brightness at
+		runtime.
+
 config AD525X_DPOT
 	tristate "Analog Devices Digital Potentiometers"
 	depends on (I2C || SPI) && SYSFS
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_PHANTOM)		+= phantom.o
 obj-$(CONFIG_QCOM_COINCELL)	+= qcom-coincell.o
 obj-$(CONFIG_QCOM_FASTRPC)	+= fastrpc.o
 obj-$(CONFIG_RP1_PIO)		+= rp1-pio.o
+obj-$(CONFIG_WS2812_PIO_RP1)	+= ws2812-pio-rp1.o
 obj-$(CONFIG_SENSORS_BH1770)	+= bh1770glc.o
 obj-$(CONFIG_SENSORS_APDS990X)	+= apds990x.o
 obj-$(CONFIG_ENCLOSURE_SERVICES) += enclosure.o
--- /dev/null
+++ b/drivers/misc/ws2812-pio-rp1.c
@@ -0,0 +1,507 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Raspberry Pi PIO-based WS2812 driver
+ *
+ * Copyright (C) 2014-2024 Raspberry Pi Ltd.
+ *
+ * Author: Phil Elwell (phil@raspberrypi.com)
+ *
+ * Based on the ws2812 driver by Gordon Hollingworth <gordon@raspberrypi.com>
+ */
+
+#include <linux/cdev.h>
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/fcntl.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/pio_rp1.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/gpio/consumer.h>
+
+#define DRIVER_NAME	"ws2812-pio-rp1"
+#define MAX_INSTANCES	4
+
+#define RESET_US	50
+#define PIXEL_BYTES	4
+
+struct ws2812_pio_rp1_state {
+	struct device	*dev;
+	struct gpio_desc *gpiod;
+	struct gpio_desc *power_gpiod;
+	uint		gpio;
+	PIO		pio;
+	uint		sm;
+	uint		offset;
+
+	u8		*buffer;
+	u8		*pixbuf;
+	u32		pixbuf_size;
+	u32		write_end;
+
+	u8		brightness;
+	u32		invert;
+	u32		num_leds;
+	u32		xfer_end_us;
+	bool		is_rgbw;
+	struct delayed_work deferred_work;
+
+	struct completion dma_completion;
+	struct cdev	cdev;
+	dev_t		dev_num;
+	const char	*dev_name;
+};
+
+static			DEFINE_MUTEX(ws2812_pio_mutex);
+static			DEFINE_IDA(ws2812_pio_ida);
+static long		ws2812_pio_ref_count;
+static struct class	*ws2812_pio_class;
+static dev_t		ws2812_pio_dev_num;
+/*
+ * WS2812B gamma correction
+ *	GammaE=255*(res/255).^(1/.45)
+ *	From: http://rgb-123.com/ws2812-color-output/
+ */
+
+static const u8 ws2812_gamma[] = {
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2,
+	2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5,
+	6, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 9, 10, 10, 11, 11,
+	11, 12, 12, 13, 13, 13, 14, 14, 15, 15, 16, 16, 17, 17, 18, 18,
+	19, 19, 20, 21, 21, 22, 22, 23, 23, 24, 25, 25, 26, 27, 27, 28,
+	29, 29, 30, 31, 31, 32, 33, 34, 34, 35, 36, 37, 37, 38, 39, 40,
+	40, 41, 42, 43, 44, 45, 46, 46, 47, 48, 49, 50, 51, 52, 53, 54,
+	55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70,
+	71, 72, 73, 74, 76, 77, 78, 79, 80, 81, 83, 84, 85, 86, 88, 89,
+	90, 91, 93, 94, 95, 96, 98, 99, 100, 102, 103, 104, 106, 107, 109, 110,
+	111, 113, 114, 116, 117, 119, 120, 121, 123, 124, 126, 128, 129, 131, 132, 134,
+	135, 137, 138, 140, 142, 143, 145, 146, 148, 150, 151, 153, 155, 157, 158, 160,
+	162, 163, 165, 167, 169, 170, 172, 174, 176, 178, 179, 181, 183, 185, 187, 189,
+	191, 193, 194, 196, 198, 200, 202, 204, 206, 208, 210, 212, 214, 216, 218, 220,
+	222, 224, 227, 229, 231, 233, 235, 237, 239, 241, 244, 246, 248, 250, 252, 255
+};
+
+// ------ //
+// ws2812 //
+// ------ //
+
+#define ws2812_wrap_target 0
+#define ws2812_wrap 3
+
+#define ws2812_T1 3
+#define ws2812_T2 4
+#define ws2812_T3 3
+
+static const uint16_t ws2812_program_instructions[] = {
+		//     .wrap_target
+	0x6221,	//  0: out    x, 1            side 0 [2]
+	0x1223,	//  1: jmp    !x, 3           side 1 [2]
+	0x1300,	//  2: jmp    0               side 1 [3]
+	0xa342,	//  3: nop                    side 0 [3]
+		//     .wrap
+};
+
+static const struct pio_program ws2812_program = {
+	.instructions = ws2812_program_instructions,
+	.length = 4,
+	.origin = -1,
+};
+
+static inline pio_sm_config ws2812_program_get_default_config(uint offset)
+{
+	pio_sm_config c = pio_get_default_sm_config();
+
+	sm_config_set_wrap(&c, offset + ws2812_wrap_target, offset + ws2812_wrap);
+	sm_config_set_sideset(&c, 1, false, false);
+	return c;
+}
+
+static inline void ws2812_program_init(PIO pio, uint sm, uint offset, uint pin, uint freq,
+				       bool rgbw)
+{
+	int cycles_per_bit = ws2812_T1 + ws2812_T2 + ws2812_T3;
+	struct fp24_8 div;
+	pio_sm_config c;
+
+	pio_gpio_init(pio, pin);
+	pio_sm_set_consecutive_pindirs(pio, sm, pin, 1, true);
+	c = ws2812_program_get_default_config(offset);
+	sm_config_set_sideset_pins(&c, pin);
+	sm_config_set_out_shift(&c, false, true, rgbw ? 32 : 24);
+	sm_config_set_fifo_join(&c, PIO_FIFO_JOIN_TX);
+	div = make_fp24_8(clock_get_hz(clk_sys), freq * cycles_per_bit);
+	sm_config_set_clkdiv(&c, div);
+	pio_sm_init(pio, sm, offset, &c);
+	pio_sm_set_enabled(pio, sm, true);
+}
+
+static uint8_t ws2812_apply_gamma(uint8_t brightness, uint8_t val)
+{
+	int bright;
+
+	if (!val)
+		return 0;
+	bright = (val * brightness) / 255;
+	return ws2812_gamma[bright];
+}
+
+static inline uint8_t *rgbw_u32(const struct ws2812_pio_rp1_state *state,
+			       uint8_t r, uint8_t g, uint8_t b, uint8_t w, uint8_t *p)
+{
+	p[0] = ws2812_apply_gamma(state->brightness, w);
+	p[1] = ws2812_apply_gamma(state->brightness, b);
+	p[2] = ws2812_apply_gamma(state->brightness, r);
+	p[3] = ws2812_apply_gamma(state->brightness, g);
+	return p + 4;
+}
+
+static void ws2812_dma_complete(void *param)
+{
+	struct ws2812_pio_rp1_state *state = param;
+
+	complete(&state->dma_completion);
+}
+
+static void ws2812_update_leds(struct ws2812_pio_rp1_state *state, uint length)
+{
+	init_completion(&state->dma_completion);
+	if (!pio_sm_xfer_data(state->pio, state->sm, PIO_DIR_TO_SM, length, state->buffer, 0,
+			      (void (*)(void *))ws2812_dma_complete, state)) {
+		wait_for_completion(&state->dma_completion);
+		usleep_range(RESET_US, RESET_US + 100);
+	}
+}
+
+static void ws2812_clear_leds(struct ws2812_pio_rp1_state *state)
+{
+	uint8_t *p_buffer;
+	uint length;
+	int i;
+
+	p_buffer = state->buffer;
+	for (i = 0; i < state->num_leds; i++)
+		p_buffer = rgbw_u32(state, 0, 0, 0, 0, p_buffer);
+
+	length = (void *)p_buffer - (void *)state->buffer;
+
+	ws2812_update_leds(state, length);
+}
+
+/*
+ * Function to write the RGB buffer to the WS2812 leds, the input buffer
+ * contains a sequence of up to num_leds RGB32 integers, these are then
+ * gamma-corrected before being sent to the PIO state machine.
+ */
+
+static ssize_t ws2812_pio_rp1_write(struct file *filp, const char __user *buf, size_t count,
+				    loff_t *ppos)
+{
+	struct ws2812_pio_rp1_state *state;
+	uint32_t pixbuf_size;
+	unsigned long delay;
+	loff_t pos = *ppos;
+	int err = 0;
+
+	state = (struct ws2812_pio_rp1_state *)filp->private_data;
+	pixbuf_size = state->pixbuf_size;
+
+	if (pos > pixbuf_size)
+		return -EFBIG;
+
+	if (count > pixbuf_size) {
+		err = -EFBIG;
+		count = pixbuf_size;
+	}
+
+	if (pos + count > pixbuf_size) {
+		if (!err)
+			err = -ENOSPC;
+
+		count = pixbuf_size - pos;
+	}
+
+	if (!pos && count == 1) {
+		if (copy_from_user(&state->brightness, buf, 1))
+			return -EFAULT;
+	} else {
+		if (copy_from_user(state->pixbuf + pos, buf, count))
+			return -EFAULT;
+		pos += count;
+		state->write_end = (u32)pos;
+	}
+
+	*ppos = pos;
+
+	delay = (state->write_end == pixbuf_size) ? 0 : HZ / 20;
+	schedule_delayed_work(&state->deferred_work, delay);
+
+	return err ? err : count;
+}
+
+static void ws2812_pio_rp1_deferred_work(struct work_struct *work)
+{
+	struct ws2812_pio_rp1_state *state =
+		container_of(work, struct ws2812_pio_rp1_state, deferred_work.work);
+	uint8_t *p_buffer;
+	uint32_t *p_rgb;
+	int blank_bytes;
+	uint length;
+	int i;
+
+	blank_bytes = state->pixbuf_size - state->write_end;
+	if (blank_bytes > 0)
+		memset(state->pixbuf + state->write_end, 0, blank_bytes);
+
+	p_rgb = (uint32_t *)state->pixbuf;
+	p_buffer = state->buffer;
+
+	for (i = 0; i < state->num_leds; i++) {
+		uint32_t rgbw_pix = *(p_rgb++);
+
+		p_buffer = rgbw_u32(state,
+				    (uint8_t)(rgbw_pix >> 0),
+				    (uint8_t)(rgbw_pix >> 8),
+				    (uint8_t)(rgbw_pix >> 16),
+				    (uint8_t)(rgbw_pix >> 24),
+				    p_buffer);
+	}
+
+	length = (void *)p_buffer - (void *)state->buffer;
+
+	ws2812_update_leds(state, length);
+}
+
+static int ws2812_pio_rp1_open(struct inode *inode, struct file *file)
+{
+	struct ws2812_pio_rp1_state *state;
+
+	state  = container_of(inode->i_cdev, struct ws2812_pio_rp1_state, cdev);
+	file->private_data = state;
+
+	return 0;
+}
+
+const struct file_operations ws2812_pio_rp1_fops = {
+	.owner = THIS_MODULE,
+	.write = ws2812_pio_rp1_write,
+	.open = ws2812_pio_rp1_open,
+};
+
+/*
+ * Probe function
+ */
+static int ws2812_pio_rp1_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct of_phandle_args of_args = { 0 };
+	struct ws2812_pio_rp1_state *state;
+	struct device *dev = &pdev->dev;
+	struct device *char_dev;
+	const char *dev_name;
+	uint32_t brightness;
+	bool is_rp1;
+	int minor;
+	int ret;
+
+	state = devm_kzalloc(dev, sizeof(*state), GFP_KERNEL);
+	if (IS_ERR(state))
+		return PTR_ERR(state);
+
+	state->dev = dev;
+
+	platform_set_drvdata(pdev, state);
+
+	ret = of_property_read_u32(np, "rpi,num-leds", &state->num_leds);
+	if (ret)
+		return dev_err_probe(dev, ret, "Could not get num-leds\n");
+
+	brightness = 255;
+	of_property_read_u32(np, "rpi,brightness", &brightness);
+	state->brightness = min(brightness, 255);
+
+	state->pixbuf_size = state->num_leds * PIXEL_BYTES;
+
+	state->is_rgbw = of_property_read_bool(np, "rpi,rgbw");
+	state->gpiod = devm_gpiod_get(dev, "leds", GPIOD_ASIS);
+	if (IS_ERR(state->gpiod))
+		return dev_err_probe(dev, PTR_ERR(state->gpiod),
+				     "Could not get a gpio\n");
+
+	/* This must be an RP1 GPIO in the first bank, and retrieve the offset. */
+	/* Unfortunately I think this has to be done by parsing the gpios property */
+
+	/* This really shouldn't fail, given that we have a gpiod */
+	if (of_parse_phandle_with_args(np, "leds-gpios", "#gpio-cells", 0, &of_args))
+		return dev_err_probe(dev, -EINVAL,
+				     "Can't find gpio declaration\n");
+
+	is_rp1 = of_device_is_compatible(of_args.np, "raspberrypi,rp1-gpio");
+	of_node_put(of_args.np);
+	if (!is_rp1 || of_args.args_count != 2)
+		return dev_err_probe(dev, -EINVAL,
+				     "Not an RP1 gpio\n");
+
+	state->gpio = of_args.args[0];
+
+	state->pixbuf = devm_kmalloc(dev, state->pixbuf_size, GFP_KERNEL);
+	if (state->pixbuf == NULL)
+		return -ENOMEM;
+
+	state->buffer = devm_kmalloc(dev, state->num_leds * PIXEL_BYTES, GFP_KERNEL);
+	if (state->buffer == NULL)
+		return -ENOMEM;
+
+	ret = of_property_read_string(np, "dev-name", &dev_name);
+	if (ret) {
+		pr_err("Failed to read 'dev-name' property\n");
+		return ret;
+	}
+
+	state->pio = pio_open();
+	if (IS_ERR(state->pio))
+		return dev_err_probe(dev, PTR_ERR(state->pio),
+				     "Could not open PIO\n");
+
+	state->sm = pio_claim_unused_sm(state->pio, false);
+	if ((int)state->sm < 0) {
+		dev_err(dev, "No free PIO SM\n");
+		ret = -EBUSY;
+		goto fail_pio;
+	}
+
+	state->offset = pio_add_program(state->pio, &ws2812_program);
+	if (state->offset == PIO_ORIGIN_ANY) {
+		dev_err(dev, "Not enough PIO program space\n");
+		ret = -EBUSY;
+		goto fail_pio;
+	}
+
+	pio_sm_config_xfer(state->pio, state->sm, PIO_DIR_TO_SM, state->num_leds * sizeof(int), 1);
+
+	pio_sm_clear_fifos(state->pio, state->sm);
+	pio_sm_set_clkdiv(state->pio, state->sm, make_fp24_8(1, 1));
+	ws2812_program_init(state->pio, state->sm, state->offset, state->gpio, 800000,
+			    state->is_rgbw);
+
+	mutex_lock(&ws2812_pio_mutex);
+
+	if (!ws2812_pio_ref_count) {
+		ret = alloc_chrdev_region(&ws2812_pio_dev_num, 0, MAX_INSTANCES, DRIVER_NAME);
+		if (ret < 0) {
+			dev_err(dev, "alloc_chrdev_region failed (rc=%d)\n", ret);
+			goto fail_mutex;
+		}
+
+		ws2812_pio_class = class_create(DRIVER_NAME);
+		if (IS_ERR(ws2812_pio_class)) {
+			pr_err("Unable to create class " DRIVER_NAME "\n");
+			ret = PTR_ERR(ws2812_pio_class);
+			goto fail_chrdev;
+		}
+	}
+
+	ws2812_pio_ref_count++;
+
+	minor = ida_alloc_range(&ws2812_pio_ida, 0, MAX_INSTANCES - 1, GFP_KERNEL);
+	if (minor < 0) {
+		pr_err("No free instances\n");
+		ret = minor;
+		goto fail_class;
+
+	}
+
+	mutex_unlock(&ws2812_pio_mutex);
+
+	state->dev_num = MKDEV(MAJOR(ws2812_pio_dev_num), minor);
+	state->dev_name = devm_kasprintf(dev, GFP_KERNEL, dev_name, minor);
+
+	char_dev = device_create(ws2812_pio_class, NULL, state->dev_num, NULL, state->dev_name);
+
+	if (IS_ERR(char_dev)) {
+		pr_err("Unable to create device %s\n", state->dev_name);
+		ret = PTR_ERR(char_dev);
+		goto fail_ida;
+	}
+
+	state->cdev.owner = THIS_MODULE;
+	cdev_init(&state->cdev, &ws2812_pio_rp1_fops);
+
+	ret = cdev_add(&state->cdev, state->dev_num, 1);
+	if (ret) {
+		pr_err("cdev_add failed\n");
+		goto fail_device;
+	}
+
+	INIT_DELAYED_WORK(&state->deferred_work, ws2812_pio_rp1_deferred_work);
+
+	ws2812_clear_leds(state);
+
+	dev_info(&pdev->dev, "Instantiated %d LEDs on GPIO %d as /dev/%s\n",
+		 state->num_leds, state->gpio, state->dev_name);
+
+	return 0;
+
+fail_device:
+	device_destroy(ws2812_pio_class, state->dev_num);
+fail_ida:
+	mutex_lock(&ws2812_pio_mutex);
+	ida_free(&ws2812_pio_ida, minor);
+fail_class:
+	ws2812_pio_ref_count--;
+	if (ws2812_pio_ref_count)
+		goto fail_mutex;
+	class_destroy(ws2812_pio_class);
+fail_chrdev:
+	unregister_chrdev_region(ws2812_pio_dev_num, MAX_INSTANCES);
+fail_mutex:
+	mutex_unlock(&ws2812_pio_mutex);
+fail_pio:
+	pio_close(state->pio);
+
+	return ret;
+}
+
+static void ws2812_pio_rp1_remove(struct platform_device *pdev)
+{
+	struct ws2812_pio_rp1_state *state = platform_get_drvdata(pdev);
+
+	cancel_delayed_work(&state->deferred_work);
+	platform_set_drvdata(pdev, NULL);
+
+	cdev_del(&state->cdev);
+	device_destroy(ws2812_pio_class, state->dev_num);
+
+	mutex_lock(&ws2812_pio_mutex);
+	ida_free(&ws2812_pio_ida, MINOR(state->dev_num));
+	ws2812_pio_ref_count--;
+	if (!ws2812_pio_ref_count) {
+		class_destroy(ws2812_pio_class);
+		unregister_chrdev_region(ws2812_pio_dev_num, MAX_INSTANCES);
+	}
+	mutex_unlock(&ws2812_pio_mutex);
+
+	pio_close(state->pio);
+}
+
+static const struct of_device_id ws2812_pio_rp1_match[] = {
+	{ .compatible = "raspberrypi,ws2812-pio-rp1" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ws2812_pio_rp1_match);
+
+static struct platform_driver ws2812_pio_rp1_driver = {
+	.driver = {
+		.name = "ws2812-pio-rp1",
+		.of_match_table = ws2812_pio_rp1_match,
+	},
+	.probe = ws2812_pio_rp1_probe,
+	.remove_new  = ws2812_pio_rp1_remove,
+};
+module_platform_driver(ws2812_pio_rp1_driver);
+
+MODULE_DESCRIPTION("WS2812 PIO RP1 driver");
+MODULE_AUTHOR("Phil Elwell");
+MODULE_LICENSE("GPL");