[PATCH v9 1/3] backlight arcxcnn add arc to vendor prefix

[PATCH v9 1/3] backlight arcxcnn add arc to vendor prefix

[Olimpiu Dejeu]

backlight: Add arc to vendor prefixes
Signed-off-by: Olimpiu Dejeu <olimpiu@arcticsand.com>
---
v8 => v9:
- Version updated to match other patch in set. No other changes.
v8:
- Version to match other patches in set

 Documentation/devicetree/bindings/vendor-prefixes.txt | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
index 16d3b5e..6f33a4b 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.txt
+++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
@@ -28,6 +28,7 @@ andestech	Andes Technology Corporation
 apm	Applied Micro Circuits Corporation (APM)
 aptina	Aptina Imaging
 arasan	Arasan Chip Systems
+arc	Arctic Sand
 aries	Aries Embedded GmbH
 arm	ARM Ltd.
 armadeus	ARMadeus Systems SARL
-- 
2.7.4

[PATCH v9 2/3] backlight arcxcnn devicetree bindings for ArcticSand

[Olimpiu Dejeu]

backlight: Add devicetree bindings for the Arctic Sand backlight driver
This patch provides devicetree bindings for the Arctic Sand
    driver submitted in the previous patch
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Olimpiu Dejeu <olimpiu@arcticsand.com>
---
v8 => v9:
- Version updated to match other patch in set. No other changes.
v7 => v8:
- Version updated to match other patch in set. No other changes.
v6 => v7:
- Version updated to match other patch in set. No other changes.
v5 => v6:
- Version updated to match other patch in set. No other changes.
v4 => v5:
- Added spaces for increased readability per Lee Jones
v3 => v4:
- Added spaces for increased readability per Lee Jones
v2 => v3:
- Version updated to match other patch in set. No other changes.
v1 => v2:
- Version updated to match other patch in set. No other changes.

 .../bindings/leds/backlight/arcxcnn_bl.txt         | 33 ++++++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/backlight/arcxcnn_bl.txt

diff --git a/Documentation/devicetree/bindings/leds/backlight/arcxcnn_bl.txt b/Documentation/devicetree/bindings/leds/backlight/arcxcnn_bl.txt
new file mode 100644
index 0000000..ecb7731
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/backlight/arcxcnn_bl.txt
@@ -0,0 +1,33 @@
+Binding for ArcticSand arc2c0608 LED driver
+
+Required properties:
+- compatible:		should be "arc,arc2c0608"
+- reg:			slave address
+
+Optional properties:
+- default-brightness:	brightness value on boot, value from: 0-4095
+- label:		The name of the backlight device
+			See Documentation/devicetree/bindings/leds/common.txt
+- led-sources:		List of enabled channels from 0 to 5.
+			See Documentation/devicetree/bindings/leds/common.txt
+
+- arc,led-config-0:	setting for register ILED_CONFIG_0
+- arc,led-config-1:	setting for register ILED_CONFIG_1
+- arc,dim-freq:		PWM mode frequence setting (bits [3:0] used)
+- arc,comp-config:	setting for register CONFIG_COMP
+- arc,filter-config:	setting for register FILTER_CONFIG
+- arc,trim-config:	setting for register IMAXTUNE
+
+Note: Optional properties not specified will default to values in IC EPROM
+
+Example:
+
+arc2c0608@30 {
+	compatible = "arc,arc2c0608";
+	reg = <0x30>;
+	default-brightness = <500>;
+	label = "lcd-backlight";
+	linux,default-trigger = "backlight";
+	led-sources = <0 1 2 5>;
+};
+
-- 
2.7.4

[PATCH v9 3/3] backlight arcxcnn add support for ArcticSand devices

[Olimpiu Dejeu]

backlight: Add support for Arctic Sand LED backlight driver chips
This driver provides support for the Arctic Sand arc2c0608 chip, 
    and provides a framework to support future devices.
Reviewed-by: Daniel Thompson <daniel.thompson-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Signed-off-by: Olimpiu Dejeu <olimpiu-eV7fy4qpoLhpLGFMi4vTTA@public.gmane.org>
---
v8 => v9:
- Addressing kbuild test robot WARNING: PTR_ERR_OR_ZERO can be used
v7 => v8:
- Version updated to match other patch in set. No other changes.
v6 => v7:
- Addressing issues brought up by Daniel Thompson
v5 => v6:
- Addressing issues brought up by Daniel Thompson
v4 => v5:
- Code style changes per Joe Perches and Jingoo Han
v3 => v4:
- Code style changes per Joe Perches and Jingoo Han
v2 => v3:
- Renamed variables to comply with conventions on naming
- Corrected device name in arcxcnn.h
v1 => v2:
- Removed "magic numbers" to initialize registers
- Cleaned up device tree bindings
- Fixed code style to address comments and pass "checkpatch"
- Removed unneeded debug and testing code


 drivers/video/backlight/Kconfig      |   7 +
 drivers/video/backlight/Makefile     |   1 +
 drivers/video/backlight/arcxcnn_bl.c | 419 +++++++++++++++++++++++++++++++++++
 3 files changed, 427 insertions(+)
 create mode 100644 drivers/video/backlight/arcxcnn_bl.c

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 5ffa4b4..4e1d2ad 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -460,6 +460,13 @@ config BACKLIGHT_BD6107
 	help
 	  If you have a Rohm BD6107 say Y to enable the backlight driver.
 
+config BACKLIGHT_ARCXCNN
+	tristate "Backlight driver for the Arctic Sands ARCxCnnnn family"
+	depends on I2C
+	help
+	  If you have an ARCxCnnnn family backlight say Y to enable
+	  the backlight driver.
+
 endif # BACKLIGHT_CLASS_DEVICE
 
 endif # BACKLIGHT_LCD_SUPPORT
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index 16ec534..8905129 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -55,3 +55,4 @@ obj-$(CONFIG_BACKLIGHT_SKY81452)	+= sky81452-backlight.o
 obj-$(CONFIG_BACKLIGHT_TOSA)		+= tosa_bl.o
 obj-$(CONFIG_BACKLIGHT_TPS65217)	+= tps65217_bl.o
 obj-$(CONFIG_BACKLIGHT_WM831X)		+= wm831x_bl.o
+obj-$(CONFIG_BACKLIGHT_ARCXCNN) 	+= arcxcnn_bl.o
diff --git a/drivers/video/backlight/arcxcnn_bl.c b/drivers/video/backlight/arcxcnn_bl.c
new file mode 100644
index 0000000..e01b1b0
--- /dev/null
+++ b/drivers/video/backlight/arcxcnn_bl.c
@@ -0,0 +1,419 @@
+/*
+ * Backlight driver for ArcticSand ARC_X_C_0N_0N Devices
+ *
+ * Copyright 2016 ArcticSand, Inc.
+ * Author : Brian Dodge <bdodge-eV7fy4qpoLhpLGFMi4vTTA@public.gmane.org>
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/backlight.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+
+enum arcxcnn_chip_id {
+	ARC2C0608
+};
+
+/**
+ * struct arcxcnn_platform_data
+ * @name		: Backlight driver name (NULL will use default)
+ * @initial_brightness	: initial value of backlight brightness
+ * @leden		: initial LED string enables, upper bit is global on/off
+ * @led_config_0	: fading speed (period between intensity steps)
+ * @led_config_1	: misc settings, see datasheet
+ * @dim_freq		: pwm dimming frequency if in pwm mode
+ * @comp_config		: misc config, see datasheet
+ * @filter_config	: RC/PWM filter config, see datasheet
+ * @trim_config		: full scale current trim, see datasheet
+ */
+struct arcxcnn_platform_data {
+	const char *name;
+	u16 initial_brightness;
+	u8	leden;
+	u8	led_config_0;
+	u8	led_config_1;
+	u8	dim_freq;
+	u8	comp_config;
+	u8	filter_config;
+	u8	trim_config;
+};
+
+#define ARCXCNN_CMD		0x00	/* Command Register */
+#define ARCXCNN_CMD_STDBY	0x80	/*   I2C Standby */
+#define ARCXCNN_CMD_RESET	0x40	/*   Reset */
+#define ARCXCNN_CMD_BOOST	0x10	/*   Boost */
+#define ARCXCNN_CMD_OVP_MASK	0x0C	/*   --- Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_XXV	0x0C	/*   <rsvrd> Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_20V	0x08	/*   20v Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_24V	0x04	/*   24v Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_31V	0x00	/*   31.4v Over Voltage Threshold */
+#define ARCXCNN_CMD_EXT_COMP	0x01	/*   part (0) or full (1) ext. comp */
+
+#define ARCXCNN_CONFIG		0x01	/* Configuration */
+#define ARCXCNN_STATUS1		0x02	/* Status 1 */
+#define ARCXCNN_STATUS2		0x03	/* Status 2 */
+#define ARCXCNN_FADECTRL	0x04	/* Fading Control */
+#define ARCXCNN_ILED_CONFIG	0x05	/* ILED Configuration */
+#define ARCXCNN_ILED_DIM_PWM	0x00	/*   config dim mode pwm */
+#define ARCXCNN_ILED_DIM_INT	0x04	/*   config dim mode internal */
+#define ARCXCNN_LEDEN		0x06	/* LED Enable Register */
+#define ARCXCNN_LEDEN_ISETEXT	0x80	/*   Full-scale current set extern */
+#define ARCXCNN_LEDEN_MASK	0x3F	/*   LED string enables mask */
+#define ARCXCNN_LEDEN_BITS	0x06	/*   Bits of LED string enables */
+#define ARCXCNN_LEDEN_LED1	0x01
+#define ARCXCNN_LEDEN_LED2	0x02
+#define ARCXCNN_LEDEN_LED3	0x04
+#define ARCXCNN_LEDEN_LED4	0x08
+#define ARCXCNN_LEDEN_LED5	0x10
+#define ARCXCNN_LEDEN_LED6	0x20
+
+#define ARCXCNN_WLED_ISET_LSB	0x07	/* LED ISET LSB (in upper nibble) */
+#define ARCXCNN_WLED_ISET_LSB_SHIFT 0x04  /* ISET LSB Left Shift */
+#define ARCXCNN_WLED_ISET_MSB	0x08	/* LED ISET MSB (8 bits) */
+
+#define ARCXCNN_DIMFREQ		0x09
+#define ARCXCNN_COMP_CONFIG	0x0A
+#define ARCXCNN_FILT_CONFIG	0x0B
+#define ARCXCNN_IMAXTUNE	0x0C
+#define ARCXCNN_ID_MSB		0x1E
+#define ARCXCNN_ID_LSB		0x1F
+
+#define MAX_BRIGHTNESS		4095
+#define INIT_BRIGHT		60
+
+struct arcxcnn {
+	struct i2c_client *client;
+	struct backlight_device *bl;
+	struct device *dev;
+	struct arcxcnn_platform_data *pdata;
+};
+
+static int arcxcnn_update_field(struct arcxcnn *lp, u8 reg, u8 mask, u8 data)
+{
+	int ret;
+	u8 tmp;
+
+	ret = i2c_smbus_read_byte_data(lp->client, reg);
+	if (ret < 0) {
+		dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
+		return ret;
+	}
+
+	tmp = (u8)ret;
+	tmp &= ~mask;
+	tmp |= data & mask;
+
+	return i2c_smbus_write_byte_data(lp->client, reg, tmp);
+}
+
+static int arcxcnn_set_brightness(struct arcxcnn *lp, u32 brightness)
+{
+	int ret;
+	u8 val;
+
+	/* lower nibble of brightness goes in upper nibble of LSB register */
+	val = (brightness & 0xF) << ARCXCNN_WLED_ISET_LSB_SHIFT;
+	ret = i2c_smbus_write_byte_data(lp->client,
+		ARCXCNN_WLED_ISET_LSB, val);
+	if (ret < 0)
+		return ret;
+
+	/* remaining 8 bits of brightness go in MSB register */
+	val = (brightness >> 4);
+	return i2c_smbus_write_byte_data(lp->client,
+		ARCXCNN_WLED_ISET_MSB, val);
+}
+
+static int arcxcnn_bl_update_status(struct backlight_device *bl)
+{
+	struct arcxcnn *lp = bl_get_data(bl);
+	u32 brightness = bl->props.brightness;
+	int ret;
+
+	if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
+		brightness = 0;
+
+	ret = arcxcnn_set_brightness(lp, brightness);
+	if (ret)
+		return ret;
+
+	/* set power-on/off/save modes */
+	return arcxcnn_update_field(lp, ARCXCNN_CMD, ARCXCNN_CMD_STDBY,
+		(bl->props.power == 0) ? 0 : ARCXCNN_CMD_STDBY);
+}
+
+static const struct backlight_ops arcxcnn_bl_ops = {
+	.options = BL_CORE_SUSPENDRESUME,
+	.update_status = arcxcnn_bl_update_status,
+};
+
+static int arcxcnn_backlight_register(struct arcxcnn *lp)
+{
+	struct backlight_properties *props;
+	const char *name = lp->pdata->name ? : "arctic_bl";
+
+	props = devm_kzalloc(lp->dev, sizeof(*props), GFP_KERNEL);
+	if (!props)
+		return -ENOMEM;
+
+	props->type = BACKLIGHT_PLATFORM;
+	props->max_brightness = MAX_BRIGHTNESS;
+
+	if (lp->pdata->initial_brightness > props->max_brightness)
+		lp->pdata->initial_brightness = props->max_brightness;
+
+	props->brightness = lp->pdata->initial_brightness;
+
+	lp->bl = devm_backlight_device_register(lp->dev, name, lp->dev, lp,
+				       &arcxcnn_bl_ops, props);
+	return PTR_ERR_OR_ZERO(lp->bl);
+}
+
+static void arcxcnn_parse_dt(struct arcxcnn *lp)
+{
+	struct device *dev = lp->dev;
+	struct device_node *node = dev->of_node;
+	u32 prog_val, num_entry, entry, sources[ARCXCNN_LEDEN_BITS];
+	int ret;
+
+	/* device tree entry isn't required, defaults are OK */
+	if (!node)
+		return;
+
+	ret = of_property_read_string(node, "label", &lp->pdata->name);
+	if (ret < 0)
+		lp->pdata->name = NULL;
+
+	ret = of_property_read_u32(node, "default-brightness", &prog_val);
+	if (ret == 0)
+		lp->pdata->initial_brightness = prog_val;
+
+	ret = of_property_read_u32(node, "arc,led-config-0", &prog_val);
+	if (ret == 0)
+		lp->pdata->led_config_0 = (u8)prog_val;
+
+	ret = of_property_read_u32(node, "arc,led-config-1", &prog_val);
+	if (ret == 0)
+		lp->pdata->led_config_1 = (u8)prog_val;
+
+	ret = of_property_read_u32(node, "arc,dim-freq", &prog_val);
+	if (ret == 0)
+		lp->pdata->dim_freq = (u8)prog_val;
+
+	ret = of_property_read_u32(node, "arc,comp-config", &prog_val);
+	if (ret == 0)
+		lp->pdata->comp_config = (u8)prog_val;
+
+	ret = of_property_read_u32(node, "arc,filter-config", &prog_val);
+	if (ret == 0)
+		lp->pdata->filter_config = (u8)prog_val;
+
+	ret = of_property_read_u32(node, "arc,trim-config", &prog_val);
+	if (ret == 0)
+		lp->pdata->trim_config = (u8)prog_val;
+
+	ret = of_property_count_u32_elems(node, "led-sources");
+	if (ret < 0) {
+		lp->pdata->leden = ARCXCNN_LEDEN_MASK; /* all on is default */
+	} else {
+		num_entry = ret;
+		if (num_entry > ARCXCNN_LEDEN_BITS)
+			num_entry = ARCXCNN_LEDEN_BITS;
+
+		ret = of_property_read_u32_array(node, "led-sources", sources,
+					num_entry);
+		if (ret < 0) {
+			dev_err(dev, "led-sources node is invalid.\n");
+			return;
+		}
+
+		lp->pdata->leden = 0;
+
+		/* for each enable in source, set bit in led enable */
+		for (entry = 0; entry < num_entry; entry++) {
+			u8 onbit = 1 << sources[entry];
+
+			lp->pdata->leden |= onbit;
+		}
+	}
+}
+
+static int arcxcnn_probe(struct i2c_client *cl, const struct i2c_device_id *id)
+{
+	struct arcxcnn *lp;
+	int ret;
+
+	if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -EIO;
+
+	lp = devm_kzalloc(&cl->dev, sizeof(*lp), GFP_KERNEL);
+	if (!lp)
+		return -ENOMEM;
+
+	lp->client = cl;
+	lp->dev = &cl->dev;
+	lp->pdata = dev_get_platdata(&cl->dev);
+
+	/* reset the device */
+	ret = i2c_smbus_write_byte_data(lp->client,
+		ARCXCNN_CMD, ARCXCNN_CMD_RESET);
+	if (ret)
+		goto probe_err;
+
+	if (!lp->pdata) {
+		lp->pdata = devm_kzalloc(lp->dev,
+				sizeof(*lp->pdata), GFP_KERNEL);
+		if (!lp->pdata)
+			return -ENOMEM;
+
+		/* Setup defaults based on power-on defaults */
+		lp->pdata->name = NULL;
+		lp->pdata->initial_brightness = INIT_BRIGHT;
+		lp->pdata->leden = ARCXCNN_LEDEN_MASK;
+
+		lp->pdata->led_config_0 = i2c_smbus_read_byte_data(
+			lp->client, ARCXCNN_FADECTRL);
+
+		lp->pdata->led_config_1 = i2c_smbus_read_byte_data(
+			lp->client, ARCXCNN_ILED_CONFIG);
+		/* insure dim mode is not default pwm */
+		lp->pdata->led_config_1 |= ARCXCNN_ILED_DIM_INT;
+
+		lp->pdata->dim_freq = i2c_smbus_read_byte_data(
+			lp->client, ARCXCNN_DIMFREQ);
+
+		lp->pdata->comp_config = i2c_smbus_read_byte_data(
+			lp->client, ARCXCNN_COMP_CONFIG);
+
+		lp->pdata->filter_config = i2c_smbus_read_byte_data(
+			lp->client, ARCXCNN_FILT_CONFIG);
+
+		lp->pdata->trim_config = i2c_smbus_read_byte_data(
+			lp->client, ARCXCNN_IMAXTUNE);
+
+		if (IS_ENABLED(CONFIG_OF))
+			arcxcnn_parse_dt(lp);
+	}
+
+	i2c_set_clientdata(cl, lp);
+
+	/* constrain settings to what is possible */
+	if (lp->pdata->initial_brightness > MAX_BRIGHTNESS)
+		lp->pdata->initial_brightness = MAX_BRIGHTNESS;
+
+	/* set initial brightness */
+	ret = arcxcnn_set_brightness(lp, lp->pdata->initial_brightness);
+	if (ret)
+		goto probe_err;
+
+	/* set other register values directly */
+	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_FADECTRL,
+		lp->pdata->led_config_0);
+	if (ret)
+		goto probe_err;
+
+	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_ILED_CONFIG,
+		lp->pdata->led_config_1);
+	if (ret)
+		goto probe_err;
+
+	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_DIMFREQ,
+		lp->pdata->dim_freq);
+	if (ret)
+		goto probe_err;
+
+	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_COMP_CONFIG,
+		lp->pdata->comp_config);
+	if (ret)
+		goto probe_err;
+
+	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_FILT_CONFIG,
+		lp->pdata->filter_config);
+	if (ret)
+		goto probe_err;
+
+	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_IMAXTUNE,
+		lp->pdata->trim_config);
+	if (ret)
+		goto probe_err;
+
+	/* set initial LED Enables */
+	arcxcnn_update_field(lp, ARCXCNN_LEDEN,
+		ARCXCNN_LEDEN_MASK, lp->pdata->leden);
+
+	ret = arcxcnn_backlight_register(lp);
+	if (ret)
+		goto probe_register_err;
+
+	backlight_update_status(lp->bl);
+
+	return 0;
+
+probe_register_err:
+	dev_err(lp->dev,
+		"failed to register backlight.\n");
+
+probe_err:
+	dev_err(lp->dev,
+		"failure ret: %d\n", ret);
+	return ret;
+}
+
+static int arcxcnn_remove(struct i2c_client *cl)
+{
+	struct arcxcnn *lp = i2c_get_clientdata(cl);
+
+	/* disable all strings (ignore errors) */
+	i2c_smbus_write_byte_data(lp->client,
+		ARCXCNN_LEDEN, 0x00);
+	/* reset the device (ignore errors) */
+	i2c_smbus_write_byte_data(lp->client,
+		ARCXCNN_CMD, ARCXCNN_CMD_RESET);
+
+	lp->bl->props.brightness = 0;
+
+	backlight_update_status(lp->bl);
+
+	return 0;
+}
+
+static const struct of_device_id arcxcnn_dt_ids[] = {
+	{ .compatible = "arc,arc2c0608" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, arcxcnn_dt_ids);
+
+static const struct i2c_device_id arcxcnn_ids[] = {
+	{"arc2c0608", ARC2C0608},
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, arcxcnn_ids);
+
+static struct i2c_driver arcxcnn_driver = {
+	.driver = {
+		.name = "arcxcnn_bl",
+		.of_match_table = of_match_ptr(arcxcnn_dt_ids),
+	},
+	.probe = arcxcnn_probe,
+	.remove = arcxcnn_remove,
+	.id_table = arcxcnn_ids,
+};
+module_i2c_driver(arcxcnn_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Brian Dodge <bdodge-eV7fy4qpoLhpLGFMi4vTTA@public.gmane.org>");
+MODULE_DESCRIPTION("ARCXCNN Backlight driver");
-- 
2.7.4

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Re: [PATCH v9 3/3] backlight arcxcnn add support for ArcticSand devices

[Lee Jones]

On Tue, 21 Mar 2017, Olimpiu Dejeu wrote:

> backlight: Add support for Arctic Sand LED backlight driver chips
> This driver provides support for the Arctic Sand arc2c0608 chip, 
>     and provides a framework to support future devices.
> Reviewed-by: Daniel Thompson <daniel.thompson-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> Signed-off-by: Olimpiu Dejeu <olimpiu-eV7fy4qpoLhpLGFMi4vTTA@public.gmane.org>
> ---
> v8 => v9:
> - Addressing kbuild test robot WARNING: PTR_ERR_OR_ZERO can be used
> v7 => v8:
> - Version updated to match other patch in set. No other changes.
> v6 => v7:
> - Addressing issues brought up by Daniel Thompson
> v5 => v6:
> - Addressing issues brought up by Daniel Thompson
> v4 => v5:
> - Code style changes per Joe Perches and Jingoo Han
> v3 => v4:
> - Code style changes per Joe Perches and Jingoo Han
> v2 => v3:
> - Renamed variables to comply with conventions on naming
> - Corrected device name in arcxcnn.h
> v1 => v2:
> - Removed "magic numbers" to initialize registers
> - Cleaned up device tree bindings
> - Fixed code style to address comments and pass "checkpatch"
> - Removed unneeded debug and testing code
> 
> 
>  drivers/video/backlight/Kconfig      |   7 +
>  drivers/video/backlight/Makefile     |   1 +
>  drivers/video/backlight/arcxcnn_bl.c | 419 +++++++++++++++++++++++++++++++++++
>  3 files changed, 427 insertions(+)
>  create mode 100644 drivers/video/backlight/arcxcnn_bl.c

Applied this (and the correct (v9) version of [PATCH 2/3] too).

> diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
> index 5ffa4b4..4e1d2ad 100644
> --- a/drivers/video/backlight/Kconfig
> +++ b/drivers/video/backlight/Kconfig
> @@ -460,6 +460,13 @@ config BACKLIGHT_BD6107
>  	help
>  	  If you have a Rohm BD6107 say Y to enable the backlight driver.
>  
> +config BACKLIGHT_ARCXCNN
> +	tristate "Backlight driver for the Arctic Sands ARCxCnnnn family"
> +	depends on I2C
> +	help
> +	  If you have an ARCxCnnnn family backlight say Y to enable
> +	  the backlight driver.
> +
>  endif # BACKLIGHT_CLASS_DEVICE
>  
>  endif # BACKLIGHT_LCD_SUPPORT
> diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
> index 16ec534..8905129 100644
> --- a/drivers/video/backlight/Makefile
> +++ b/drivers/video/backlight/Makefile
> @@ -55,3 +55,4 @@ obj-$(CONFIG_BACKLIGHT_SKY81452)	+= sky81452-backlight.o
>  obj-$(CONFIG_BACKLIGHT_TOSA)		+= tosa_bl.o
>  obj-$(CONFIG_BACKLIGHT_TPS65217)	+= tps65217_bl.o
>  obj-$(CONFIG_BACKLIGHT_WM831X)		+= wm831x_bl.o
> +obj-$(CONFIG_BACKLIGHT_ARCXCNN) 	+= arcxcnn_bl.o
> diff --git a/drivers/video/backlight/arcxcnn_bl.c b/drivers/video/backlight/arcxcnn_bl.c
> new file mode 100644
> index 0000000..e01b1b0
> --- /dev/null
> +++ b/drivers/video/backlight/arcxcnn_bl.c
> @@ -0,0 +1,419 @@
> +/*
> + * Backlight driver for ArcticSand ARC_X_C_0N_0N Devices
> + *
> + * Copyright 2016 ArcticSand, Inc.
> + * Author : Brian Dodge <bdodge-eV7fy4qpoLhpLGFMi4vTTA@public.gmane.org>
> + *
> + * 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.
> + *
> + * You should have received a copy of the GNU General Public License along
> + * with this program; if not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/backlight.h>
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/slab.h>
> +
> +enum arcxcnn_chip_id {
> +	ARC2C0608
> +};
> +
> +/**
> + * struct arcxcnn_platform_data
> + * @name		: Backlight driver name (NULL will use default)
> + * @initial_brightness	: initial value of backlight brightness
> + * @leden		: initial LED string enables, upper bit is global on/off
> + * @led_config_0	: fading speed (period between intensity steps)
> + * @led_config_1	: misc settings, see datasheet
> + * @dim_freq		: pwm dimming frequency if in pwm mode
> + * @comp_config		: misc config, see datasheet
> + * @filter_config	: RC/PWM filter config, see datasheet
> + * @trim_config		: full scale current trim, see datasheet
> + */
> +struct arcxcnn_platform_data {
> +	const char *name;
> +	u16 initial_brightness;
> +	u8	leden;
> +	u8	led_config_0;
> +	u8	led_config_1;
> +	u8	dim_freq;
> +	u8	comp_config;
> +	u8	filter_config;
> +	u8	trim_config;
> +};
> +
> +#define ARCXCNN_CMD		0x00	/* Command Register */
> +#define ARCXCNN_CMD_STDBY	0x80	/*   I2C Standby */
> +#define ARCXCNN_CMD_RESET	0x40	/*   Reset */
> +#define ARCXCNN_CMD_BOOST	0x10	/*   Boost */
> +#define ARCXCNN_CMD_OVP_MASK	0x0C	/*   --- Over Voltage Threshold */
> +#define ARCXCNN_CMD_OVP_XXV	0x0C	/*   <rsvrd> Over Voltage Threshold */
> +#define ARCXCNN_CMD_OVP_20V	0x08	/*   20v Over Voltage Threshold */
> +#define ARCXCNN_CMD_OVP_24V	0x04	/*   24v Over Voltage Threshold */
> +#define ARCXCNN_CMD_OVP_31V	0x00	/*   31.4v Over Voltage Threshold */
> +#define ARCXCNN_CMD_EXT_COMP	0x01	/*   part (0) or full (1) ext. comp */
> +
> +#define ARCXCNN_CONFIG		0x01	/* Configuration */
> +#define ARCXCNN_STATUS1		0x02	/* Status 1 */
> +#define ARCXCNN_STATUS2		0x03	/* Status 2 */
> +#define ARCXCNN_FADECTRL	0x04	/* Fading Control */
> +#define ARCXCNN_ILED_CONFIG	0x05	/* ILED Configuration */
> +#define ARCXCNN_ILED_DIM_PWM	0x00	/*   config dim mode pwm */
> +#define ARCXCNN_ILED_DIM_INT	0x04	/*   config dim mode internal */
> +#define ARCXCNN_LEDEN		0x06	/* LED Enable Register */
> +#define ARCXCNN_LEDEN_ISETEXT	0x80	/*   Full-scale current set extern */
> +#define ARCXCNN_LEDEN_MASK	0x3F	/*   LED string enables mask */
> +#define ARCXCNN_LEDEN_BITS	0x06	/*   Bits of LED string enables */
> +#define ARCXCNN_LEDEN_LED1	0x01
> +#define ARCXCNN_LEDEN_LED2	0x02
> +#define ARCXCNN_LEDEN_LED3	0x04
> +#define ARCXCNN_LEDEN_LED4	0x08
> +#define ARCXCNN_LEDEN_LED5	0x10
> +#define ARCXCNN_LEDEN_LED6	0x20
> +
> +#define ARCXCNN_WLED_ISET_LSB	0x07	/* LED ISET LSB (in upper nibble) */
> +#define ARCXCNN_WLED_ISET_LSB_SHIFT 0x04  /* ISET LSB Left Shift */
> +#define ARCXCNN_WLED_ISET_MSB	0x08	/* LED ISET MSB (8 bits) */
> +
> +#define ARCXCNN_DIMFREQ		0x09
> +#define ARCXCNN_COMP_CONFIG	0x0A
> +#define ARCXCNN_FILT_CONFIG	0x0B
> +#define ARCXCNN_IMAXTUNE	0x0C
> +#define ARCXCNN_ID_MSB		0x1E
> +#define ARCXCNN_ID_LSB		0x1F
> +
> +#define MAX_BRIGHTNESS		4095
> +#define INIT_BRIGHT		60
> +
> +struct arcxcnn {
> +	struct i2c_client *client;
> +	struct backlight_device *bl;
> +	struct device *dev;
> +	struct arcxcnn_platform_data *pdata;
> +};
> +
> +static int arcxcnn_update_field(struct arcxcnn *lp, u8 reg, u8 mask, u8 data)
> +{
> +	int ret;
> +	u8 tmp;
> +
> +	ret = i2c_smbus_read_byte_data(lp->client, reg);
> +	if (ret < 0) {
> +		dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
> +		return ret;
> +	}
> +
> +	tmp = (u8)ret;
> +	tmp &= ~mask;
> +	tmp |= data & mask;
> +
> +	return i2c_smbus_write_byte_data(lp->client, reg, tmp);
> +}
> +
> +static int arcxcnn_set_brightness(struct arcxcnn *lp, u32 brightness)
> +{
> +	int ret;
> +	u8 val;
> +
> +	/* lower nibble of brightness goes in upper nibble of LSB register */
> +	val = (brightness & 0xF) << ARCXCNN_WLED_ISET_LSB_SHIFT;
> +	ret = i2c_smbus_write_byte_data(lp->client,
> +		ARCXCNN_WLED_ISET_LSB, val);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* remaining 8 bits of brightness go in MSB register */
> +	val = (brightness >> 4);
> +	return i2c_smbus_write_byte_data(lp->client,
> +		ARCXCNN_WLED_ISET_MSB, val);
> +}
> +
> +static int arcxcnn_bl_update_status(struct backlight_device *bl)
> +{
> +	struct arcxcnn *lp = bl_get_data(bl);
> +	u32 brightness = bl->props.brightness;
> +	int ret;
> +
> +	if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
> +		brightness = 0;
> +
> +	ret = arcxcnn_set_brightness(lp, brightness);
> +	if (ret)
> +		return ret;
> +
> +	/* set power-on/off/save modes */
> +	return arcxcnn_update_field(lp, ARCXCNN_CMD, ARCXCNN_CMD_STDBY,
> +		(bl->props.power == 0) ? 0 : ARCXCNN_CMD_STDBY);
> +}
> +
> +static const struct backlight_ops arcxcnn_bl_ops = {
> +	.options = BL_CORE_SUSPENDRESUME,
> +	.update_status = arcxcnn_bl_update_status,
> +};
> +
> +static int arcxcnn_backlight_register(struct arcxcnn *lp)
> +{
> +	struct backlight_properties *props;
> +	const char *name = lp->pdata->name ? : "arctic_bl";
> +
> +	props = devm_kzalloc(lp->dev, sizeof(*props), GFP_KERNEL);
> +	if (!props)
> +		return -ENOMEM;
> +
> +	props->type = BACKLIGHT_PLATFORM;
> +	props->max_brightness = MAX_BRIGHTNESS;
> +
> +	if (lp->pdata->initial_brightness > props->max_brightness)
> +		lp->pdata->initial_brightness = props->max_brightness;
> +
> +	props->brightness = lp->pdata->initial_brightness;
> +
> +	lp->bl = devm_backlight_device_register(lp->dev, name, lp->dev, lp,
> +				       &arcxcnn_bl_ops, props);
> +	return PTR_ERR_OR_ZERO(lp->bl);
> +}
> +
> +static void arcxcnn_parse_dt(struct arcxcnn *lp)
> +{
> +	struct device *dev = lp->dev;
> +	struct device_node *node = dev->of_node;
> +	u32 prog_val, num_entry, entry, sources[ARCXCNN_LEDEN_BITS];
> +	int ret;
> +
> +	/* device tree entry isn't required, defaults are OK */
> +	if (!node)
> +		return;
> +
> +	ret = of_property_read_string(node, "label", &lp->pdata->name);
> +	if (ret < 0)
> +		lp->pdata->name = NULL;
> +
> +	ret = of_property_read_u32(node, "default-brightness", &prog_val);
> +	if (ret == 0)
> +		lp->pdata->initial_brightness = prog_val;
> +
> +	ret = of_property_read_u32(node, "arc,led-config-0", &prog_val);
> +	if (ret == 0)
> +		lp->pdata->led_config_0 = (u8)prog_val;
> +
> +	ret = of_property_read_u32(node, "arc,led-config-1", &prog_val);
> +	if (ret == 0)
> +		lp->pdata->led_config_1 = (u8)prog_val;
> +
> +	ret = of_property_read_u32(node, "arc,dim-freq", &prog_val);
> +	if (ret == 0)
> +		lp->pdata->dim_freq = (u8)prog_val;
> +
> +	ret = of_property_read_u32(node, "arc,comp-config", &prog_val);
> +	if (ret == 0)
> +		lp->pdata->comp_config = (u8)prog_val;
> +
> +	ret = of_property_read_u32(node, "arc,filter-config", &prog_val);
> +	if (ret == 0)
> +		lp->pdata->filter_config = (u8)prog_val;
> +
> +	ret = of_property_read_u32(node, "arc,trim-config", &prog_val);
> +	if (ret == 0)
> +		lp->pdata->trim_config = (u8)prog_val;
> +
> +	ret = of_property_count_u32_elems(node, "led-sources");
> +	if (ret < 0) {
> +		lp->pdata->leden = ARCXCNN_LEDEN_MASK; /* all on is default */
> +	} else {
> +		num_entry = ret;
> +		if (num_entry > ARCXCNN_LEDEN_BITS)
> +			num_entry = ARCXCNN_LEDEN_BITS;
> +
> +		ret = of_property_read_u32_array(node, "led-sources", sources,
> +					num_entry);
> +		if (ret < 0) {
> +			dev_err(dev, "led-sources node is invalid.\n");
> +			return;
> +		}
> +
> +		lp->pdata->leden = 0;
> +
> +		/* for each enable in source, set bit in led enable */
> +		for (entry = 0; entry < num_entry; entry++) {
> +			u8 onbit = 1 << sources[entry];
> +
> +			lp->pdata->leden |= onbit;
> +		}
> +	}
> +}
> +
> +static int arcxcnn_probe(struct i2c_client *cl, const struct i2c_device_id *id)
> +{
> +	struct arcxcnn *lp;
> +	int ret;
> +
> +	if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
> +		return -EIO;
> +
> +	lp = devm_kzalloc(&cl->dev, sizeof(*lp), GFP_KERNEL);
> +	if (!lp)
> +		return -ENOMEM;
> +
> +	lp->client = cl;
> +	lp->dev = &cl->dev;
> +	lp->pdata = dev_get_platdata(&cl->dev);
> +
> +	/* reset the device */
> +	ret = i2c_smbus_write_byte_data(lp->client,
> +		ARCXCNN_CMD, ARCXCNN_CMD_RESET);
> +	if (ret)
> +		goto probe_err;
> +
> +	if (!lp->pdata) {
> +		lp->pdata = devm_kzalloc(lp->dev,
> +				sizeof(*lp->pdata), GFP_KERNEL);
> +		if (!lp->pdata)
> +			return -ENOMEM;
> +
> +		/* Setup defaults based on power-on defaults */
> +		lp->pdata->name = NULL;
> +		lp->pdata->initial_brightness = INIT_BRIGHT;
> +		lp->pdata->leden = ARCXCNN_LEDEN_MASK;
> +
> +		lp->pdata->led_config_0 = i2c_smbus_read_byte_data(
> +			lp->client, ARCXCNN_FADECTRL);
> +
> +		lp->pdata->led_config_1 = i2c_smbus_read_byte_data(
> +			lp->client, ARCXCNN_ILED_CONFIG);
> +		/* insure dim mode is not default pwm */
> +		lp->pdata->led_config_1 |= ARCXCNN_ILED_DIM_INT;
> +
> +		lp->pdata->dim_freq = i2c_smbus_read_byte_data(
> +			lp->client, ARCXCNN_DIMFREQ);
> +
> +		lp->pdata->comp_config = i2c_smbus_read_byte_data(
> +			lp->client, ARCXCNN_COMP_CONFIG);
> +
> +		lp->pdata->filter_config = i2c_smbus_read_byte_data(
> +			lp->client, ARCXCNN_FILT_CONFIG);
> +
> +		lp->pdata->trim_config = i2c_smbus_read_byte_data(
> +			lp->client, ARCXCNN_IMAXTUNE);
> +
> +		if (IS_ENABLED(CONFIG_OF))
> +			arcxcnn_parse_dt(lp);
> +	}
> +
> +	i2c_set_clientdata(cl, lp);
> +
> +	/* constrain settings to what is possible */
> +	if (lp->pdata->initial_brightness > MAX_BRIGHTNESS)
> +		lp->pdata->initial_brightness = MAX_BRIGHTNESS;
> +
> +	/* set initial brightness */
> +	ret = arcxcnn_set_brightness(lp, lp->pdata->initial_brightness);
> +	if (ret)
> +		goto probe_err;
> +
> +	/* set other register values directly */
> +	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_FADECTRL,
> +		lp->pdata->led_config_0);
> +	if (ret)
> +		goto probe_err;
> +
> +	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_ILED_CONFIG,
> +		lp->pdata->led_config_1);
> +	if (ret)
> +		goto probe_err;
> +
> +	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_DIMFREQ,
> +		lp->pdata->dim_freq);
> +	if (ret)
> +		goto probe_err;
> +
> +	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_COMP_CONFIG,
> +		lp->pdata->comp_config);
> +	if (ret)
> +		goto probe_err;
> +
> +	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_FILT_CONFIG,
> +		lp->pdata->filter_config);
> +	if (ret)
> +		goto probe_err;
> +
> +	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_IMAXTUNE,
> +		lp->pdata->trim_config);
> +	if (ret)
> +		goto probe_err;
> +
> +	/* set initial LED Enables */
> +	arcxcnn_update_field(lp, ARCXCNN_LEDEN,
> +		ARCXCNN_LEDEN_MASK, lp->pdata->leden);
> +
> +	ret = arcxcnn_backlight_register(lp);
> +	if (ret)
> +		goto probe_register_err;
> +
> +	backlight_update_status(lp->bl);
> +
> +	return 0;
> +
> +probe_register_err:
> +	dev_err(lp->dev,
> +		"failed to register backlight.\n");
> +
> +probe_err:
> +	dev_err(lp->dev,
> +		"failure ret: %d\n", ret);
> +	return ret;
> +}
> +
> +static int arcxcnn_remove(struct i2c_client *cl)
> +{
> +	struct arcxcnn *lp = i2c_get_clientdata(cl);
> +
> +	/* disable all strings (ignore errors) */
> +	i2c_smbus_write_byte_data(lp->client,
> +		ARCXCNN_LEDEN, 0x00);
> +	/* reset the device (ignore errors) */
> +	i2c_smbus_write_byte_data(lp->client,
> +		ARCXCNN_CMD, ARCXCNN_CMD_RESET);
> +
> +	lp->bl->props.brightness = 0;
> +
> +	backlight_update_status(lp->bl);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id arcxcnn_dt_ids[] = {
> +	{ .compatible = "arc,arc2c0608" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, arcxcnn_dt_ids);
> +
> +static const struct i2c_device_id arcxcnn_ids[] = {
> +	{"arc2c0608", ARC2C0608},
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, arcxcnn_ids);
> +
> +static struct i2c_driver arcxcnn_driver = {
> +	.driver = {
> +		.name = "arcxcnn_bl",
> +		.of_match_table = of_match_ptr(arcxcnn_dt_ids),
> +	},
> +	.probe = arcxcnn_probe,
> +	.remove = arcxcnn_remove,
> +	.id_table = arcxcnn_ids,
> +};
> +module_i2c_driver(arcxcnn_driver);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR("Brian Dodge <bdodge-eV7fy4qpoLhpLGFMi4vTTA@public.gmane.org>");
> +MODULE_DESCRIPTION("ARCXCNN Backlight driver");

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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