leds: add LED driver for CR0014114 board

This patch adds a LED class driver for the RGB LEDs found on
the Crane Merchandising System CR0014114 LEDs board.
Signed-off-by: Oleh Kravchenko <oleg@kaa.org.ua>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>

drivers/leds/Kconfig

@@ -104,6 +104,19 @@ config LEDS_CPCAP
 	  This option enables support for LEDs offered by Motorola's
 	  CPCAP PMIC.
 
+config LEDS_CR0014114
+	tristate "LED Support for Crane CR0014114"
+	depends on LEDS_CLASS
+	depends on SPI
+	depends on OF
+	help
+	  This option enables support for CR0014114 LED Board which
+	  is widely used in vending machines produced by
+	  Crane Merchandising Systems.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called leds-cr0014114.
+
 config LEDS_LM3530
 	tristate "LCD Backlight driver for LM3530"
 	depends on LEDS_CLASS

drivers/leds/Makefile

@@ -78,6 +78,7 @@ obj-$(CONFIG_LEDS_MT6323)		+= leds-mt6323.o
 obj-$(CONFIG_LEDS_LM3692X)		+= leds-lm3692x.o
 
 # LED SPI Drivers
+obj-$(CONFIG_LEDS_CR0014114)		+= leds-cr0014114.o
 obj-$(CONFIG_LEDS_DAC124S085)		+= leds-dac124s085.o
 
 # LED Userspace Drivers

drivers/leds/leds-cr0014114.c

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018 Crane Merchandising Systems. All rights reserved.
+// Copyright (C) 2018 Oleh Kravchenko <oleg@kaa.org.ua>
+
+#include <linux/delay.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/spi/spi.h>
+#include <linux/workqueue.h>
+#include <uapi/linux/uleds.h>
+
+/*
+ *  CR0014114 SPI protocol descrtiption:
+ *  +----+-----------------------------------+----+
+ *  | CMD|             BRIGHTNESS            |CRC |
+ *  +----+-----------------------------------+----+
+ *  |    | LED0| LED1| LED2| LED3| LED4| LED5|    |
+ *  |    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    |
+ *  |    |R|G|B|R|G|B|R|G|B|R|G|B|R|G|B|R|G|B|    |
+ *  | 1  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1  |
+ *  |    |1|1|1|1|1|1|1|1|1|1|1|1|1|1|1|1|1|1|    |
+ *  |    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    |
+ *  |    |               18                  |    |
+ *  +----+-----------------------------------+----+
+ *  |                    20                       |
+ *  +---------------------------------------------+
+ *
+ *  PS: Boards can be connected to the chain:
+ *      SPI -> board0 -> board1 -> board2 ..
+ */
+
+/* CR0014114 SPI commands */
+#define CR_SET_BRIGHTNESS	0x80
+#define CR_INIT_REENUMERATE	0x81
+#define CR_NEXT_REENUMERATE	0x82
+
+/* CR0014114 default settings */
+#define CR_MAX_BRIGHTNESS	GENMASK(6, 0)
+#define CR_FW_DELAY_MSEC	10
+#define CR_RECOUNT_DELAY	(HZ * 3600)
+
+struct cr0014114_led {
+	char			name[LED_MAX_NAME_SIZE];
+	struct cr0014114	*priv;
+	struct led_classdev	ldev;
+	u8			brightness;
+};
+
+struct cr0014114 {
+	bool			do_recount;
+	size_t			count;
+	struct delayed_work	work;
+	struct device		*dev;
+	struct mutex		lock;
+	struct spi_device	*spi;
+	u8			*buf;
+	unsigned long		delay;
+	struct cr0014114_led	leds[];
+};
+
+static void cr0014114_calc_crc(u8 *buf, const size_t len)
+{
+	size_t	i;
+	u8	crc;
+
+	for (i = 1, crc = 1; i < len - 1; i++)
+		crc += buf[i];
+	crc |= BIT(7);
+
+	/* special case when CRC matches the SPI commands */
+	if (crc == CR_SET_BRIGHTNESS ||
+	    crc == CR_INIT_REENUMERATE ||
+	    crc == CR_NEXT_REENUMERATE)
+		crc = 0xfe;
+
+	buf[len - 1] = crc;
+}
+
+static int cr0014114_recount(struct cr0014114 *priv)
+{
+	int	ret;
+	size_t	i;
+	u8	cmd;
+
+	dev_dbg(priv->dev, "LEDs recount is started\n");
+
+	cmd = CR_INIT_REENUMERATE;
+	ret = spi_write(priv->spi, &cmd, sizeof(cmd));
+	if (ret)
+		goto err;
+
+	cmd = CR_NEXT_REENUMERATE;
+	for (i = 0; i < priv->count; i++) {
+		msleep(CR_FW_DELAY_MSEC);
+
+		ret = spi_write(priv->spi, &cmd, sizeof(cmd));
+		if (ret)
+			goto err;
+	}
+
+err:
+	dev_dbg(priv->dev, "LEDs recount is finished\n");
+
+	if (ret)
+		dev_err(priv->dev, "with error %d", ret);
+
+	return ret;
+}
+
+static int cr0014114_sync(struct cr0014114 *priv)
+{
+	int		ret;
+	size_t		i;
+	unsigned long	udelay, now = jiffies;
+
+	/* to avoid SPI mistiming with firmware we should wait some time */
+	if (time_after(priv->delay, now)) {
+		udelay = jiffies_to_usecs(priv->delay - now);
+		usleep_range(udelay, udelay + 1);
+	}
+
+	if (unlikely(priv->do_recount)) {
+		ret = cr0014114_recount(priv);
+		if (ret)
+			goto err;
+
+		priv->do_recount = false;
+		msleep(CR_FW_DELAY_MSEC);
+	}
+
+	priv->buf[0] = CR_SET_BRIGHTNESS;
+	for (i = 0; i < priv->count; i++)
+		priv->buf[i + 1] = priv->leds[i].brightness;
+	cr0014114_calc_crc(priv->buf, priv->count + 2);
+	ret = spi_write(priv->spi, priv->buf, priv->count + 2);
+
+err:
+	priv->delay = jiffies + msecs_to_jiffies(CR_FW_DELAY_MSEC);
+
+	return ret;
+}
+
+static void cr0014114_recount_work(struct work_struct *work)
+{
+	int			ret;
+	struct cr0014114	*priv = container_of(work,
+						     struct cr0014114,
+						     work.work);
+
+	mutex_lock(&priv->lock);
+	priv->do_recount = true;
+	ret = cr0014114_sync(priv);
+	mutex_unlock(&priv->lock);
+
+	if (ret)
+		dev_warn(priv->dev, "sync of LEDs failed %d\n", ret);
+
+	schedule_delayed_work(&priv->work, CR_RECOUNT_DELAY);
+}
+
+static int cr0014114_set_sync(struct led_classdev *ldev,
+			      enum led_brightness brightness)
+{
+	int			ret;
+	struct cr0014114_led    *led = container_of(ldev,
+						    struct cr0014114_led,
+						    ldev);
+
+	dev_dbg(led->priv->dev, "Set brightness of %s to %d\n",
+		led->name, brightness);
+
+	mutex_lock(&led->priv->lock);
+	led->brightness = (u8)brightness;
+	ret = cr0014114_sync(led->priv);
+	mutex_unlock(&led->priv->lock);
+
+	return ret;
+}
+
+static int cr0014114_probe_dt(struct cr0014114 *priv)
+{
+	size_t			i = 0;
+	struct cr0014114_led	*led;
+	struct fwnode_handle	*child;
+	struct device_node	*np;
+	int			ret;
+	const char		*str;
+
+	device_for_each_child_node(priv->dev, child) {
+		np = to_of_node(child);
+		led = &priv->leds[i];
+
+		ret = fwnode_property_read_string(child, "label", &str);
+		if (ret)
+			snprintf(led->name, sizeof(led->name),
+				 "cr0014114::");
+		else
+			snprintf(led->name, sizeof(led->name),
+				 "cr0014114:%s", str);
+
+		fwnode_property_read_string(child, "linux,default-trigger",
+					    &led->ldev.default_trigger);
+
+		led->priv			  = priv;
+		led->ldev.name			  = led->name;
+		led->ldev.max_brightness	  = CR_MAX_BRIGHTNESS;
+		led->ldev.brightness_set_blocking = cr0014114_set_sync;
+
+		ret = devm_of_led_classdev_register(priv->dev, np,
+						    &led->ldev);
+		if (ret) {
+			dev_err(priv->dev,
+				"failed to register LED device %s, err %d",
+				led->name, ret);
+			fwnode_handle_put(child);
+			return ret;
+		}
+
+		led->ldev.dev->of_node = np;
+
+		i++;
+	}
+
+	return 0;
+}
+
+static int cr0014114_probe(struct spi_device *spi)
+{
+	struct cr0014114	*priv;
+	size_t			count;
+	int			ret;
+
+	count = device_get_child_node_count(&spi->dev);
+	if (!count) {
+		dev_err(&spi->dev, "LEDs are not defined in device tree!");
+		return -ENODEV;
+	}
+
+	priv = devm_kzalloc(&spi->dev,
+			    sizeof(*priv) + sizeof(*priv->leds) * count,
+			    GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->buf = devm_kzalloc(&spi->dev, count + 2, GFP_KERNEL);
+	if (!priv->buf)
+		return -ENOMEM;
+
+	mutex_init(&priv->lock);
+	INIT_DELAYED_WORK(&priv->work, cr0014114_recount_work);
+	priv->count	= count;
+	priv->dev	= &spi->dev;
+	priv->spi	= spi;
+	priv->delay	= jiffies -
+			  msecs_to_jiffies(CR_FW_DELAY_MSEC);
+
+	priv->do_recount = true;
+	ret = cr0014114_sync(priv);
+	if (ret) {
+		dev_err(priv->dev, "first recount failed %d\n", ret);
+		return ret;
+	}
+
+	priv->do_recount = true;
+	ret = cr0014114_sync(priv);
+	if (ret) {
+		dev_err(priv->dev, "second recount failed %d\n", ret);
+		return ret;
+	}
+
+	ret = cr0014114_probe_dt(priv);
+	if (ret)
+		return ret;
+
+	/* setup recount work to workaround buggy firmware */
+	schedule_delayed_work(&priv->work, CR_RECOUNT_DELAY);
+
+	spi_set_drvdata(spi, priv);
+
+	return 0;
+}
+
+static int cr0014114_remove(struct spi_device *spi)
+{
+	struct cr0014114 *priv = spi_get_drvdata(spi);
+
+	cancel_delayed_work_sync(&priv->work);
+	mutex_destroy(&priv->lock);
+
+	return 0;
+}
+
+static const struct of_device_id cr0014114_dt_ids[] = {
+	{ .compatible = "crane,cr0014114", },
+	{},
+};
+
+MODULE_DEVICE_TABLE(of, cr0014114_dt_ids);
+
+static struct spi_driver cr0014114_driver = {
+	.probe		= cr0014114_probe,
+	.remove		= cr0014114_remove,
+	.driver = {
+		.name		= KBUILD_MODNAME,
+		.of_match_table	= cr0014114_dt_ids,
+	},
+};
+
+module_spi_driver(cr0014114_driver);
+
+MODULE_AUTHOR("Oleh Kravchenko <oleg@kaa.org.ua>");
+MODULE_DESCRIPTION("cr0014114 LED driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("spi:cr0014114");