Date:   Fri, 5 May 2017 08:57:12 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Olimpiu Dejeu <olimpiu@...ticsand.com>
Cc:     robh@...nel.org, linux-kernel@...r.kernel.org,
        linux-fbdev@...r.kernel.org, devicetree@...r.kernel.org,
        jingoohan1@...il.com, bdodge@...ticsand.com, joe@...ches.com,
        daniel.thompson@...aro.org, lkp@...el.com, fengguang.wu@...el.com
Subject: Re: [PATCH v10 3/3] backlight arcxcnn add support for ArcticSand
 devices

On Wed, 03 May 2017, Olimpiu Dejeu wrote:

> backlight: Add support for Arctic Sand LED backlight driver chips

This should be the subject line of the patch.

Out of interest, how are you submitting your patches?

If you're not already, you should be using:

  `git format-patch ...`
  `git send-email ...`
  
> This driver provides support for the Arctic Sand arc2c0608 chip, 
>     and provides a framework to support future devices.

'\n' here.

> Reviewed-by: Daniel Thompson <daniel.thompson@...aro.org>
> Signed-off-by: Olimpiu Dejeu <olimpiu@...ticsand.com>

Biggest point however is that this patch is already in Mainline.

> ---
> v9 => v10:
> - Per Rob Herring's request changed vendor-prefix to arctic
> 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@...ticsand.com>
> + *
> + * 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, "arctic,led-config-0", &prog_val);
> +	if (ret == 0)
> +		lp->pdata->led_config_0 = (u8)prog_val;
> +
> +	ret = of_property_read_u32(node, "arctic,led-config-1", &prog_val);
> +	if (ret == 0)
> +		lp->pdata->led_config_1 = (u8)prog_val;
> +
> +	ret = of_property_read_u32(node, "arctic,dim-freq", &prog_val);
> +	if (ret == 0)
> +		lp->pdata->dim_freq = (u8)prog_val;
> +
> +	ret = of_property_read_u32(node, "arctic,comp-config", &prog_val);
> +	if (ret == 0)
> +		lp->pdata->comp_config = (u8)prog_val;
> +
> +	ret = of_property_read_u32(node, "arctic,filter-config", &prog_val);
> +	if (ret == 0)
> +		lp->pdata->filter_config = (u8)prog_val;
> +
> +	ret = of_property_read_u32(node, "arctic,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 = "arctic,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@...ticsand.com>");
> +MODULE_DESCRIPTION("ARCXCNN Backlight driver");

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

Powered by blists - more mailing lists