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

Olimpiu Dejeu
2017-03-21T16:58:48Z

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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