Message-Id: <ae23cf26135a586440419aaa764f3a70de913c4a.1458140954.git.robin@protonic.nl>
Date:	Wed, 16 Mar 2016 16:52:09 +0100
From:	Robin van der Gracht <robin@...tonic.nl>
To:	Miguel Ojeda Sandonis <miguel.ojeda.sandonis@...il.com>
Cc:	Rob Herring <robh+dt@...nel.org>, Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Thierry Reding <treding@...dia.com>,
	Jonathan Cameron <jic23@...nel.org>,
	Lee Jones <lee.jones@...aro.org>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Stefan Wahren <stefan.wahren@...e.com>,
	Philipp Zabel <philipp.zabel@...il.com>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	Robin van der Gracht <robin@...tonic.nl>
Subject: [PATCH v4 2/2] auxdisplay: ht16k33: Driver for LED controller

This is a driver for the Holtek HT16K33 RAM mapping LED controller with keyscan.

Signed-off-by: Robin van der Gracht <robin@...tonic.nl>
---

Changes in v4:
 - Removed trailing dot from patch title
 - Removed unused defines
 - Fixed brightness range (0 was presumed to be off but its 1/16 duty cycle)
 - No longer checking 'reschedule' before setting it in ht16k33_keypad_scan()
 - Use more efficient ffs() to find changed rows in ht16k33_keypad_scan()
 - Use BIT macro in ht16k33_keypad_scan()
 - Removed extra space in return line from ht16k33_bl_check_fb()
 - Removed redundant 'Out of Memory' prints from ht16k33_probe()
 - Changed bustype from BUS_HOST to BUS_I2C

 .../devicetree/bindings/display/ht16k33.txt        |  42 ++
 drivers/auxdisplay/Kconfig                         |   9 +
 drivers/auxdisplay/Makefile                        |   1 +
 drivers/auxdisplay/ht16k33.c                       | 563 +++++++++++++++++++++
 4 files changed, 615 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/display/ht16k33.txt
 create mode 100644 drivers/auxdisplay/ht16k33.c

diff --git a/Documentation/devicetree/bindings/display/ht16k33.txt b/Documentation/devicetree/bindings/display/ht16k33.txt
new file mode 100644
index 0000000..20ef996
--- /dev/null
+++ b/Documentation/devicetree/bindings/display/ht16k33.txt
@@ -0,0 +1,42 @@
+Holtek ht16k33 RAM mapping 16*8 LED controller driver with keyscan
+-------------------------------------------------------------------------------
+
+Required properties:
+- compatible:		"ht,ht16k33"
+- reg:			I2C slave address of the chip.
+- interrupt-parent:	A phandle pointing to the interrupt controller\
+			serving the interrupt for this chip.
+- interrupts:		Interrupt specification for the key pressed interrupt.
+- refresh-rate-hz:	Display update interval in HZ.
+- debounce-delay-ms:	Debouncing interval time in microseconds.
+- linux,keymap: 	The keymap for keys as described in the binding
+			document (devicetree/bindings/input/matrix-keymap.txt).
+
+Optional properties:
+- linux,no-autorepeat:	Disable keyrepeat.
+- default-brightness-level: Initial brightness level [0-15] (default: 15).
+
+Example:
+
+&i2c1 {
+	ht16k33: ht16k33@70 {
+		compatible = "ht,ht16k33";
+		reg = <0x70>;
+		refresh-rate-hz = <20>;
+		debounce-delay-ms = <50>;
+		interrupt-parent = <&gpio4>;
+		interrupts = <5 (IRQ_TYPE_LEVEL_HIGH | IRQ_TYPE_EDGE_RISING)>;
+		linux,keymap = <
+			MATRIX_KEY(2, 0, KEY_F6)
+			MATRIX_KEY(3, 0, KEY_F8)
+			MATRIX_KEY(4, 0, KEY_F0)
+			MATRIX_KEY(5, 0, KEY_F4)
+			MATRIX_KEY(6, 0, KEY_F2)
+			MATRIX_KEY(2, 1, KEY_F5)
+			MATRIX_KEY(3, 1, KEY_F7)
+			MATRIX_KEY(4, 1, KEY_F9)
+			MATRIX_KEY(5, 1, KEY_F3)
+			MATRIX_KEY(6, 1, KEY_F1)
+		>;
+	};
+};
diff --git a/drivers/auxdisplay/Kconfig b/drivers/auxdisplay/Kconfig
index c07e725..75ad4f5 100644
--- a/drivers/auxdisplay/Kconfig
+++ b/drivers/auxdisplay/Kconfig
@@ -119,4 +119,13 @@ config CFAG12864B_RATE
 	  If you compile this as a module, you can still override this
 	  value using the module parameters.
 
+config HT16K33
+	tristate "Holtek Ht16K33 LED controller with keyscan"
+	depends on FB && OF && I2C && INPUT
+	select INPUT_MATRIXKMAP
+	select FB_BACKLIGHT
+	help
+	  Say yes here to add support for Holtek HT16K33, RAM mapping 16*8
+	  LED controller driver with keyscan.
+
 endif # AUXDISPLAY
diff --git a/drivers/auxdisplay/Makefile b/drivers/auxdisplay/Makefile
index 8a8936a..d7c9ef5 100644
--- a/drivers/auxdisplay/Makefile
+++ b/drivers/auxdisplay/Makefile
@@ -4,3 +4,4 @@
 
 obj-$(CONFIG_KS0108)		+= ks0108.o
 obj-$(CONFIG_CFAG12864B)	+= cfag12864b.o cfag12864bfb.o
+obj-$(CONFIG_HT16K33)		+= ht16k33.o
diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c
new file mode 100644
index 0000000..3d61b19
--- /dev/null
+++ b/drivers/auxdisplay/ht16k33.c
@@ -0,0 +1,563 @@
+/*
+ * HT16K33 driver
+ *
+ * Author: Robin van der Gracht <robin@...tonic.nl>
+ *
+ * Copyright: (C) 2016 Protonic Holland.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/i2c.h>
+#include <linux/of.h>
+#include <linux/fb.h>
+#include <linux/slab.h>
+#include <linux/backlight.h>
+#include <linux/input.h>
+#include <linux/input/matrix_keypad.h>
+#include <linux/workqueue.h>
+#include <linux/mm.h>
+
+/* Registers */
+#define REG_SYSTEM_SETUP		0x20
+#define REG_SYSTEM_SETUP_OSC_ON		BIT(0)
+
+#define REG_DISPLAY_SETUP		0x80
+#define REG_DISPLAY_SETUP_ON		BIT(0)
+
+#define REG_ROWINT_SET			0xA0
+#define REG_ROWINT_SET_INT_EN		BIT(0)
+#define REG_ROWINT_SET_INT_ACT_HIGH	BIT(1)
+
+#define REG_BRIGHTNESS			0xE0
+
+/* Defines */
+#define DRIVER_NAME			"ht16k33"
+
+#define MIN_BRIGHTNESS			0x1
+#define MAX_BRIGHTNESS			0x10
+
+#define HT16K33_MATRIX_LED_MAX_COLS	8
+#define HT16K33_MATRIX_LED_MAX_ROWS	16
+#define HT16K33_MATRIX_KEYPAD_MAX_COLS	3
+#define HT16K33_MATRIX_KEYPAD_MAX_ROWS	12
+
+#define HT16K33_FB_SIZE			(HT16K33_MATRIX_LED_MAX_COLS * 2)
+#define BYTES_PER_ROW			(HT16K33_MATRIX_LED_MAX_ROWS / 8)
+
+struct ht16k33_keypad {
+	struct input_dev *dev;
+	spinlock_t lock;
+	struct delayed_work work;
+	uint32_t cols;
+	uint32_t rows;
+	uint32_t row_shift;
+	uint32_t debounce_ms;
+	uint16_t last_key_state[HT16K33_MATRIX_KEYPAD_MAX_COLS];
+};
+
+struct ht16k33_fbdev {
+	struct fb_info *info;
+	uint32_t refresh_rate;
+	uint8_t *buffer;
+	uint8_t *cache;
+	struct delayed_work work;
+};
+
+struct ht16k33_priv {
+	struct i2c_client *client;
+	struct ht16k33_keypad keypad;
+	struct ht16k33_fbdev fbdev;
+	struct workqueue_struct *workqueue;
+};
+
+static struct fb_fix_screeninfo ht16k33_fb_fix = {
+	.id		= DRIVER_NAME,
+	.type		= FB_TYPE_PACKED_PIXELS,
+	.visual		= FB_VISUAL_MONO10,
+	.xpanstep	= 0,
+	.ypanstep	= 0,
+	.ywrapstep	= 0,
+	.line_length	= HT16K33_MATRIX_LED_MAX_ROWS,
+	.accel		= FB_ACCEL_NONE,
+};
+
+static struct fb_var_screeninfo ht16k33_fb_var = {
+	.xres = HT16K33_MATRIX_LED_MAX_ROWS,
+	.yres = HT16K33_MATRIX_LED_MAX_COLS,
+	.xres_virtual = HT16K33_MATRIX_LED_MAX_ROWS,
+	.yres_virtual = HT16K33_MATRIX_LED_MAX_COLS,
+	.bits_per_pixel = 1,
+	.red = { 0, 1, 0 },
+	.green = { 0, 1, 0 },
+	.blue = { 0, 1, 0 },
+	.left_margin = 0,
+	.right_margin = 0,
+	.upper_margin = 0,
+	.lower_margin = 0,
+	.vmode = FB_VMODE_NONINTERLACED,
+};
+
+static int ht16k33_display_on(struct ht16k33_priv *priv)
+{
+	uint8_t data = REG_DISPLAY_SETUP | REG_DISPLAY_SETUP_ON;
+
+	return i2c_smbus_write_byte(priv->client, data);
+}
+
+static int ht16k33_display_off(struct ht16k33_priv *priv)
+{
+	return i2c_smbus_write_byte(priv->client, REG_DISPLAY_SETUP);
+}
+
+static void ht16k33_fb_queue(struct ht16k33_priv *priv)
+{
+	struct ht16k33_fbdev *fbdev = &priv->fbdev;
+
+	queue_delayed_work(priv->workqueue, &fbdev->work,
+		msecs_to_jiffies(HZ / fbdev->refresh_rate));
+}
+
+static void ht16k33_keypad_queue(struct ht16k33_priv *priv)
+{
+	struct ht16k33_keypad *keypad = &priv->keypad;
+
+	queue_delayed_work(priv->workqueue, &keypad->work,
+		msecs_to_jiffies(keypad->debounce_ms));
+}
+
+/*
+ * This gets the fb data from cache and copies it to ht16k33 display RAM
+ */
+static void ht16k33_fb_update(struct work_struct *work)
+{
+	struct ht16k33_fbdev *fbdev =
+		container_of(work, struct ht16k33_fbdev, work.work);
+	struct ht16k33_priv *priv =
+		container_of(fbdev, struct ht16k33_priv, fbdev);
+
+	uint8_t *p1, *p2;
+	int len, pos = 0, first = -1;
+
+	p1 = fbdev->cache;
+	p2 = fbdev->buffer;
+
+	/* Search for the first byte with changes */
+	while (pos < HT16K33_FB_SIZE && first < 0) {
+		if (*(p1++) - *(p2++))
+			first = pos;
+		pos++;
+	}
+
+	/* No changes found */
+	if (first < 0)
+		goto requeue;
+
+	len = HT16K33_FB_SIZE - first;
+	p1 = fbdev->cache + HT16K33_FB_SIZE - 1;
+	p2 = fbdev->buffer + HT16K33_FB_SIZE - 1;
+
+	/* Determine i2c transfer length */
+	while (len > 1) {
+		if (*(p1--) - *(p2--))
+			break;
+		len--;
+	}
+
+	p1 = fbdev->cache + first;
+	p2 = fbdev->buffer + first;
+	if (!i2c_smbus_write_i2c_block_data(priv->client, first, len, p2))
+		memcpy(p1, p2, len);
+requeue:
+	ht16k33_fb_queue(priv);
+}
+
+static int ht16k33_keypad_start(struct input_dev *dev)
+{
+	struct ht16k33_priv *priv = input_get_drvdata(dev);
+	struct ht16k33_keypad *keypad = &priv->keypad;
+
+	/*
+	 * Schedule an immediate key scan to capture current key state;
+	 * columns will be activated and IRQs be enabled after the scan.
+	 */
+	queue_delayed_work(priv->workqueue, &keypad->work, 0);
+	return 0;
+}
+
+static void ht16k33_keypad_stop(struct input_dev *dev)
+{
+	struct ht16k33_priv *priv = input_get_drvdata(dev);
+	struct ht16k33_keypad *keypad = &priv->keypad;
+
+	cancel_delayed_work(&keypad->work);
+	/*
+	 * ht16k33_keypad_scan() will leave IRQs enabled;
+	 * we should disable them now.
+	 */
+	disable_irq_nosync(priv->client->irq);
+}
+
+static int ht16k33_initialize(struct ht16k33_priv *priv)
+{
+	uint8_t byte;
+	int err;
+	uint8_t data[HT16K33_MATRIX_LED_MAX_COLS * 2];
+
+	/* Clear RAM (8 * 16 bits) */
+	memset(data, 0, sizeof(data));
+	err = i2c_smbus_write_block_data(priv->client, 0, sizeof(data), data);
+	if (err)
+		return err;
+
+	/* Turn on internal oscillator */
+	byte = REG_SYSTEM_SETUP_OSC_ON | REG_SYSTEM_SETUP;
+	err = i2c_smbus_write_byte(priv->client, byte);
+	if (err)
+		return err;
+
+	/* Configure INT pin */
+	byte = REG_ROWINT_SET | REG_ROWINT_SET_INT_ACT_HIGH;
+	if (priv->client->irq > 0)
+		byte |= REG_ROWINT_SET_INT_EN;
+	return i2c_smbus_write_byte(priv->client, byte);
+}
+
+/*
+ * This gets the keys from keypad and reports it to input subsystem
+ */
+static void ht16k33_keypad_scan(struct work_struct *work)
+{
+	struct ht16k33_keypad *keypad =
+		container_of(work, struct ht16k33_keypad, work.work);
+	struct ht16k33_priv *priv =
+		container_of(keypad, struct ht16k33_priv, keypad);
+	const unsigned short *keycodes = keypad->dev->keycode;
+	uint16_t bits_changed, new_state[HT16K33_MATRIX_KEYPAD_MAX_COLS];
+	uint8_t data[HT16K33_MATRIX_KEYPAD_MAX_COLS * 2];
+	int row, col, code;
+	bool reschedule = false;
+
+	if (i2c_smbus_read_i2c_block_data(priv->client, 0x40, 6, data) != 6) {
+		dev_err(&priv->client->dev, "Failed to read key data\n");
+		goto end;
+	}
+
+	for (col = 0; col < keypad->cols; col++) {
+		new_state[col] = (data[col * 2 + 1] << 8) | data[col * 2];
+		if (new_state[col])
+			reschedule = true;
+		bits_changed = keypad->last_key_state[col] ^ new_state[col];
+
+		while (bits_changed) {
+			row = ffs(bits_changed) - 1;
+			code = MATRIX_SCAN_CODE(row, col, keypad->row_shift);
+			input_event(keypad->dev, EV_MSC, MSC_SCAN, code);
+			input_report_key(keypad->dev, keycodes[code],
+					 new_state[col] & BIT(row));
+			bits_changed &= ~BIT(row);
+		}
+	}
+	input_sync(keypad->dev);
+	memcpy(keypad->last_key_state, new_state, sizeof(new_state));
+
+end:
+	if (reschedule)
+		ht16k33_keypad_queue(priv);
+	else
+		enable_irq(priv->client->irq);
+}
+
+static irqreturn_t ht16k33_irq_thread(int irq, void *dev)
+{
+	struct ht16k33_priv *priv = dev;
+
+	disable_irq_nosync(priv->client->irq);
+	ht16k33_keypad_queue(priv);
+
+	return IRQ_HANDLED;
+}
+
+static int ht16k33_bl_update_status(struct backlight_device *bl)
+{
+	int brightness = bl->props.brightness;
+	struct ht16k33_priv *priv = bl_get_data(bl);
+
+	if (bl->props.power != FB_BLANK_UNBLANK ||
+	    bl->props.fb_blank != FB_BLANK_UNBLANK ||
+	    bl->props.state & BL_CORE_FBBLANK || brightness == 0) {
+		return ht16k33_display_off(priv);
+	}
+
+	ht16k33_display_on(priv);
+	return i2c_smbus_write_byte(priv->client,
+				    REG_BRIGHTNESS | (brightness - 1));
+}
+
+static int ht16k33_bl_check_fb(struct backlight_device *bl, struct fb_info *fi)
+{
+	struct ht16k33_priv *priv = bl_get_data(bl);
+
+	return (fi == NULL) || (fi->par == priv);
+}
+
+static const struct backlight_ops ht16k33_bl_ops = {
+	.update_status	= ht16k33_bl_update_status,
+	.check_fb	= ht16k33_bl_check_fb,
+};
+
+static int ht16k33_mmap(struct fb_info *info, struct vm_area_struct *vma)
+{
+	struct ht16k33_priv *priv = info->par;
+
+	return vm_insert_page(vma, vma->vm_start,
+			      virt_to_page(priv->fbdev.buffer));
+}
+
+static struct fb_ops ht16k33_fb_ops = {
+	.owner = THIS_MODULE,
+	.fb_read = fb_sys_read,
+	.fb_write = fb_sys_write,
+	.fb_fillrect = sys_fillrect,
+	.fb_copyarea = sys_copyarea,
+	.fb_imageblit = sys_imageblit,
+	.fb_mmap = ht16k33_mmap,
+};
+
+static int ht16k33_probe(struct i2c_client *client,
+				  const struct i2c_device_id *id)
+{
+	int err;
+	uint32_t rows, cols, dft_brightness;
+	struct backlight_device *bl;
+	struct backlight_properties bl_props;
+	struct ht16k33_priv *priv;
+	struct ht16k33_keypad *keypad;
+	struct ht16k33_fbdev *fbdev;
+	struct device_node *node = client->dev.of_node;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
+		dev_err(&client->dev, "i2c_check_functionality error\n");
+		return -EIO;
+	}
+
+	if (client->irq <= 0) {
+		dev_err(&client->dev, "No IRQ specified\n");
+		return -EINVAL;
+	}
+
+	priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->client = client;
+	i2c_set_clientdata(client, priv);
+	fbdev = &priv->fbdev;
+	keypad = &priv->keypad;
+
+	priv->workqueue = create_singlethread_workqueue(DRIVER_NAME "-wq");
+	if (priv->workqueue == NULL)
+		return -ENOMEM;
+
+	err = ht16k33_initialize(priv);
+	if (err)
+		goto err_destroy_wq;
+
+	/* Framebuffer (2 bytes per column) */
+	BUILD_BUG_ON(PAGE_SIZE < HT16K33_FB_SIZE);
+	fbdev->buffer = (unsigned char *) get_zeroed_page(GFP_KERNEL);
+	if (!fbdev->buffer) {
+		err = -ENOMEM;
+		goto err_free_fbdev;
+	}
+
+	fbdev->cache = devm_kmalloc(&client->dev, HT16K33_FB_SIZE, GFP_KERNEL);
+	if (!fbdev->cache) {
+		err = -ENOMEM;
+		goto err_fbdev_buffer;
+	}
+
+	fbdev->info = framebuffer_alloc(0, &client->dev);
+	if (!fbdev->info) {
+		err = -ENOMEM;
+		goto err_fbdev_buffer;
+	}
+
+	err = of_property_read_u32(node, "refresh-rate-hz",
+		&fbdev->refresh_rate);
+	if (err) {
+		dev_err(&client->dev, "refresh rate not specified\n");
+		goto err_fbdev_info;
+	}
+	fb_bl_default_curve(fbdev->info, 0, MIN_BRIGHTNESS, MAX_BRIGHTNESS);
+
+	INIT_DELAYED_WORK(&fbdev->work, ht16k33_fb_update);
+	fbdev->info->fbops = &ht16k33_fb_ops;
+	fbdev->info->screen_base = (char __iomem *) fbdev->buffer;
+	fbdev->info->screen_size = HT16K33_FB_SIZE;
+	fbdev->info->fix = ht16k33_fb_fix;
+	fbdev->info->var = ht16k33_fb_var;
+	fbdev->info->pseudo_palette = NULL;
+	fbdev->info->flags = FBINFO_FLAG_DEFAULT;
+	fbdev->info->par = priv;
+
+	err = register_framebuffer(fbdev->info);
+	if (err)
+		goto err_fbdev_info;
+
+	/* Keypad */
+	keypad->dev = devm_input_allocate_device(&client->dev);
+	if (!keypad->dev) {
+		err = -ENOMEM;
+		goto err_fbdev_unregister;
+	}
+
+	keypad->dev->name = DRIVER_NAME"-keypad";
+	keypad->dev->id.bustype = BUS_I2C;
+	keypad->dev->open = ht16k33_keypad_start;
+	keypad->dev->close = ht16k33_keypad_stop;
+
+	if (!of_get_property(node, "linux,no-autorepeat", NULL))
+		__set_bit(EV_REP, keypad->dev->evbit);
+
+	err = of_property_read_u32(node, "debounce-delay-ms",
+				   &keypad->debounce_ms);
+	if (err) {
+		dev_err(&client->dev, "key debounce delay not specified\n");
+		goto err_fbdev_unregister;
+	}
+
+	err = devm_request_threaded_irq(&client->dev, client->irq, NULL,
+					ht16k33_irq_thread,
+					IRQF_TRIGGER_RISING | IRQF_ONESHOT,
+					DRIVER_NAME, priv);
+	if (err) {
+		dev_err(&client->dev, "irq request failed %d, error %d\n",
+			client->irq, err);
+		goto err_fbdev_unregister;
+	}
+
+	disable_irq_nosync(client->irq);
+	rows = HT16K33_MATRIX_KEYPAD_MAX_ROWS;
+	cols = HT16K33_MATRIX_KEYPAD_MAX_COLS;
+	err = matrix_keypad_parse_of_params(&client->dev, &rows, &cols);
+	if (err)
+		goto err_fbdev_unregister;
+
+	err = matrix_keypad_build_keymap(NULL, NULL, rows, cols, NULL,
+					 keypad->dev);
+	if (err) {
+		dev_err(&client->dev, "failed to build keymap\n");
+		goto err_fbdev_unregister;
+	}
+
+	input_set_drvdata(keypad->dev, priv);
+	keypad->rows = rows;
+	keypad->cols = cols;
+	keypad->row_shift = get_count_order(cols);
+	INIT_DELAYED_WORK(&keypad->work, ht16k33_keypad_scan);
+
+	err = input_register_device(keypad->dev);
+	if (err)
+		goto err_fbdev_unregister;
+
+	/* Backlight */
+	memset(&bl_props, 0, sizeof(struct backlight_properties));
+	bl_props.type = BACKLIGHT_RAW;
+	bl_props.max_brightness = MAX_BRIGHTNESS;
+
+	bl = devm_backlight_device_register(&client->dev, DRIVER_NAME"-bl",
+					    &client->dev, priv,
+					    &ht16k33_bl_ops, &bl_props);
+	if (IS_ERR(bl)) {
+		dev_err(&client->dev, "failed to register backlight\n");
+		err = PTR_ERR(bl);
+		goto err_keypad_unregister;
+	}
+
+	err = of_property_read_u32(node, "default-brightness-level",
+				   &dft_brightness);
+	if (err) {
+		dft_brightness = MAX_BRIGHTNESS;
+	} else if (dft_brightness > MAX_BRIGHTNESS) {
+		dev_warn(&client->dev,
+			 "invalid default brightness level: %u, using %u\n",
+			 dft_brightness, MAX_BRIGHTNESS);
+		dft_brightness = MAX_BRIGHTNESS;
+	}
+
+	bl->props.brightness = dft_brightness;
+	ht16k33_bl_update_status(bl);
+
+	ht16k33_fb_queue(priv);
+	return 0;
+
+err_keypad_unregister:
+	input_unregister_device(keypad->dev);
+err_fbdev_unregister:
+	unregister_framebuffer(fbdev->info);
+err_fbdev_info:
+	framebuffer_release(fbdev->info);
+err_fbdev_buffer:
+	free_page((unsigned long) fbdev->buffer);
+err_free_fbdev:
+	kfree(fbdev);
+err_destroy_wq:
+	destroy_workqueue(priv->workqueue);
+
+	return err;
+}
+
+static int ht16k33_remove(struct i2c_client *client)
+{
+	struct ht16k33_priv *priv = i2c_get_clientdata(client);
+	struct ht16k33_keypad *keypad = &priv->keypad;
+	struct ht16k33_fbdev *fbdev = &priv->fbdev;
+
+	ht16k33_keypad_stop(keypad->dev);
+
+	cancel_delayed_work(&fbdev->work);
+	unregister_framebuffer(fbdev->info);
+	framebuffer_release(fbdev->info);
+	free_page((unsigned long) fbdev->buffer);
+
+	destroy_workqueue(priv->workqueue);
+	return 0;
+}
+
+static const struct i2c_device_id ht16k33_i2c_match[] = {
+	{ "ht16k33", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, ht16k33_i2c_match);
+
+static const struct of_device_id ht16k33_of_match[] = {
+	{ .compatible = "ht,ht16k33", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ht16k33_of_match);
+
+static struct i2c_driver ht16k33_driver = {
+	.probe		= ht16k33_probe,
+	.remove		= ht16k33_remove,
+	.driver		= {
+		.name		= DRIVER_NAME,
+		.of_match_table	= of_match_ptr(ht16k33_of_match),
+	},
+	.id_table = ht16k33_i2c_match,
+};
+module_i2c_driver(ht16k33_driver);
+
+MODULE_DESCRIPTION("Holtek HT16K33 driver");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Robin van der Gracht <robin@...tonic.nl>");
-- 
2.5.0

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