On 30/01/17 23:01, Olimpiu Dejeu wrote:
diff --git a/drivers/video/backlight/arcxcnn_bl.c b/drivers/video/backlight/arcxcnn_bl.c
new file mode 100644
index 0000000..284df08
--- /dev/null
+++ b/drivers/video/backlight/arcxcnn_bl.c
@@ -0,0 +1,451 @@
+/*
+ * Backlight driver for ArcticSand ARC_X_C_0N_0N Devices
+ *
+ * Copyright 2016 ArcticSand, Inc.
+ * Author : Brian Dodge <bdodge@xxxxxxxxxxxxxx>
+ *
+ * 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>
+
+#include "linux/i2c/arcxcnn.h"
+
+#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
+
+static int no_reset_on_remove;
+module_param_named(noreset, no_reset_on_remove, int, 0644);
+MODULE_PARM_DESC(noreset, "No reset on module removal");
+
+static int ibright = 60;
+module_param_named(ibright, ibright, int, 0644);
Use module_param() when names match.
+MODULE_PARM_DESC(ibright, "Initial brightness (when no plat data)");
When will there be no platform data. Hotpluggable I2C backlight
controllers aren't very common.
Also, if this *is* needed, shouldn't the permissions should be 0444?
+
+static int ileden = ARCXCNN_LEDEN_MASK;
+module_param_named(ileden, ileden, int, 0644);
+MODULE_PARM_DESC(ileden, "Initial LED String Enables (when no plat data)");
Both, as above.
+
+struct arcxcnn {
+ char chipname[64];
This is more than double the size required. Actually if the chipid is
useful to userspace it should be stored numerically.
+ struct i2c_client *client;
+ struct backlight_device *bl;
+ struct device *dev;
+ struct arcxcnn_platform_data *pdata;
+};
+
+static int arcxcnn_update_bit(struct arcxcnn *lp, u8 reg, u8 mask, u8 data)
s/_bit/_field/
+{
+ 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);
+ ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_WLED_ISET_MSB, val);
+
+ return ret;
This can be a direct return from _write_byte_data.
+}
+
+static int arcxcnn_bl_update_status(struct backlight_device *bl)
+{
+ struct arcxcnn *lp = bl_get_data(bl);
+ u32 brightness = bl->props.brightness;
+
+ if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
+ brightness = 0;
+
+ arcxcnn_set_brightness(lp, brightness);
Return code is ignored here...
+
+ /* set power-on/off/save modes */
+ arcxcnn_update_bit(lp, ARCXCNN_CMD, ARCXCNN_CMD_STDBY,
+ (bl->props.power == 0) ? 0 : ARCXCNN_CMD_STDBY);
... and here.
+ return 0;
+}
+
+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);
+ if (IS_ERR(lp->bl))
+ return PTR_ERR(lp->bl);
+
+ return 0;
+}
+
+static ssize_t arcxcnn_chip_id_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct arcxcnn *lp = dev_get_drvdata(dev);
+
+ return scnprintf(buf, PAGE_SIZE, "%s\n", lp->chipname);
+}
+
+static ssize_t arcxcnn_leden_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct arcxcnn *lp = dev_get_drvdata(dev);
+
+ return scnprintf(buf, PAGE_SIZE, "%02X\n", lp->pdata->leden);
+}
+
+static ssize_t arcxcnn_leden_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t len)
Under what circumstances can the led-sources change at runtime and
motivate this kind of interface?
+{
+ struct arcxcnn *lp = dev_get_drvdata(dev);
+ unsigned long leden;
+
+ if (kstrtoul(buf, 0, &leden))
+ return 0;
+
+ if (leden != lp->pdata->leden) {
+ /* don't allow 0 for leden, use power to turn all off */
+ if (leden == 0)
+ return -EINVAL;
+ lp->pdata->leden = leden & ARCXCNN_LEDEN_MASK;
+ arcxcnn_update_bit(lp, ARCXCNN_LEDEN,
+ ARCXCNN_LEDEN_MASK, lp->pdata->leden);
Should be a return (to pass the error code back).
+ }
+
+ return len;
+}
+
+static DEVICE_ATTR(chip_id, 0444, arcxcnn_chip_id_show, NULL);
+static DEVICE_ATTR(leden, 0664, arcxcnn_leden_show, arcxcnn_leden_store);
+
+static struct attribute *arcxcnn_attributes[] = {
+ &dev_attr_chip_id.attr,
+ &dev_attr_leden.attr,
+ NULL,
+};
+
+static const struct attribute_group arcxcnn_attr_group = {
+ .attrs = arcxcnn_attributes,
+};
+
+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;
+ u8 regval;
+ u16 chipid;
+
+ 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 */
+ i2c_smbus_write_byte_data(lp->client,
+ ARCXCNN_CMD, ARCXCNN_CMD_RESET);
+
+ /* read device ID */
+ regval = i2c_smbus_read_byte_data(lp->client, ARCXCNN_ID_MSB);
+ chipid = regval;
+ chipid <<= 8;
+
+ regval = i2c_smbus_read_byte_data(lp->client, ARCXCNN_ID_LSB);
+ chipid |= regval;
+
+ snprintf(lp->chipname, sizeof(lp->chipname),
+ "%s-%04X", id->name, chipid);
I'm curious what the chip id is and why the id is a userspace concern
rather than something the *driver* uses to confirm the probe is correct.
+
+ 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 = ibright;
+ lp->pdata->leden = ileden;
+
+ 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 */
+ arcxcnn_set_brightness(lp, lp->pdata->initial_brightness);
+
+ /* set other register values directly */
+ i2c_smbus_write_byte_data(lp->client, ARCXCNN_FADECTRL,
+ lp->pdata->led_config_0);
+ i2c_smbus_write_byte_data(lp->client, ARCXCNN_ILED_CONFIG,
+ lp->pdata->led_config_1);
+ i2c_smbus_write_byte_data(lp->client, ARCXCNN_DIMFREQ,
+ lp->pdata->dim_freq);
+ i2c_smbus_write_byte_data(lp->client, ARCXCNN_COMP_CONFIG,
+ lp->pdata->comp_config);
+ i2c_smbus_write_byte_data(lp->client, ARCXCNN_FILT_CONFIG,
+ lp->pdata->filter_config);
+ i2c_smbus_write_byte_data(lp->client, ARCXCNN_IMAXTUNE,
+ lp->pdata->trim_config);
+
+ /* set initial LED Enables */
+ arcxcnn_update_bit(lp, ARCXCNN_LEDEN,
+ ARCXCNN_LEDEN_MASK, lp->pdata->leden);
Pretty much *all* of the above functions return error codes.
+ ret = arcxcnn_backlight_register(lp);
+ if (ret) {
+ dev_err(lp->dev,
+ "failed to register backlight. err: %d\n", ret);
+ return ret;
+ }
+
+ ret = sysfs_create_group(&lp->dev->kobj, &arcxcnn_attr_group);
+ if (ret) {
+ dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
+ return ret;
+ }
+
+ backlight_update_status(lp->bl);
+
+ return 0;
+}
+
+static int arcxcnn_remove(struct i2c_client *cl)
+{
+ struct arcxcnn *lp = i2c_get_clientdata(cl);
+
+ if (!no_reset_on_remove) {
+ /* disable all strings */
+ i2c_smbus_write_byte_data(lp->client,
+ ARCXCNN_LEDEN, 0x00);
+ /* reset the device */
+ i2c_smbus_write_byte_data(lp->client,
+ ARCXCNN_CMD, ARCXCNN_CMD_RESET);
+ }
Why would userspace want to suppress this reset?
+ lp->bl->props.brightness = 0;
+
+ backlight_update_status(lp->bl);
+
+ sysfs_remove_group(&lp->dev->kobj, &arcxcnn_attr_group);
+
+ 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@xxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("ARCXCNN Backlight driver");
diff --git a/include/linux/i2c/arcxcnn.h b/include/linux/i2c/arcxcnn.h
new file mode 100644
index 0000000..e378d63
--- /dev/null
+++ b/include/linux/i2c/arcxcnn.h
There's a general trend to move unused header files out of this
directory and fold things back into the C code.
Are you expecting to add anything to the kernel (other than the driver)
that actually includes this header, if not we probably don't need it.
Daniel.
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