[PATCH v3 9/9] leds: lm3633: Introduce the lm3633 driver

From: Dan Murphy
Date: Thu Oct 11 2018 - 12:51:53 EST

Next message: Dan Murphy: "[PATCH v3 8/9] dt-bindings: leds: Add support for the LM3633"
Previous message: Thierry Reding: "Re: [PATCH V2 5/5] arm64: dts: tegra210: Add power-domains for xHCI"
In reply to: Dan Murphy: "[PATCH v3 1/9] leds: add TI LMU backlight driver"
Next in thread: Dan Murphy: "[PATCH v3 8/9] dt-bindings: leds: Add support for the LM3633"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

Introduce the LED LM3633 driver. This LED
driver has 9 total LED outputs with runtime
internal ramp configurations.

Data sheet:
http://www.ti.com/lit/ds/symlink/lm3633.pdf

Signed-off-by: Dan Murphy <dmurphy@xxxxxx>
---
drivers/leds/Kconfig | 8 +
drivers/leds/Makefile | 1 +
drivers/leds/leds-lm3633.c | 556 +++++++++++++++++++++++++++++++++++++
3 files changed, 565 insertions(+)
create mode 100644 drivers/leds/leds-lm3633.c

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 7d9a98044be4..1f9093e5d902 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -763,8 +763,16 @@ config LEDS_LM3697
Say Y to enable the LED driver for TI LMU devices.
This supports the LED device LM3697.

+config LEDS_LM3633
+ tristate "LED driver for LM3633"
+ depends on LEDS_TI_LMU_COMMON
+ help
+ Say Y to enable the LED driver for TI LMU devices.
+ This supports the LED device LM3633.
+
config LEDS_TI_LMU_COMMON
tristate "LED driver for TI LMU"
+ depends on REGMAP
help
Say Y to enable the LED driver for TI LMU devices.
This supports common features between the TI LM3532, LM3631, LM3632,
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index 6fbce7cfc41c..6ec006892fc0 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -79,6 +79,7 @@ obj-$(CONFIG_LEDS_LM3692X) += leds-lm3692x.o
obj-$(CONFIG_LEDS_SC27XX_BLTC) += leds-sc27xx-bltc.o
obj-$(CONFIG_LEDS_LM3601X) += leds-lm3601x.o
obj-$(CONFIG_LEDS_LM3697) += leds-lm3697.o
+obj-$(CONFIG_LEDS_LM3633) += leds-lm3633.o
obj-$(CONFIG_LEDS_TI_LMU_COMMON) += ti-lmu-led-common.o

# LED SPI Drivers
diff --git a/drivers/leds/leds-lm3633.c b/drivers/leds/leds-lm3633.c
new file mode 100644
index 000000000000..de8eb7b83d20
--- /dev/null
+++ b/drivers/leds/leds-lm3633.c
@@ -0,0 +1,556 @@
+// SPDX-License-Identifier: GPL-2.0
+// TI LM3633 LED chip family driver
+// Copyright (C) 2018 Texas Instruments Incorporated - http://www.ti.com/
+
+#include <linux/gpio/consumer.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+#include <linux/ti-lmu-led-common.h>
+#include <linux/regulator/consumer.h>
+
+#define LM3633_REV 0x0
+#define LM3633_RESET 0x1
+#define LM3633_HVLED_OUTPUT_CONFIG 0x10
+#define LM3633_LVLED_OUTPUT_CONFIG 0x11
+
+#define LM3633_CTRL_A_RAMP 0x12
+#define LM3633_CTRL_B_RAMP 0x13
+#define LM3633_CTRL_C_RAMP 0x14
+#define LM3633_CTRL_D_RAMP 0x15
+#define LM3633_CTRL_E_RAMP 0x16
+#define LM3633_CTRL_F_RAMP 0x17
+#define LM3633_CTRL_G_RAMP 0x18
+#define LM3633_CTRL_H_RAMP 0x19
+
+#define LM3633_CTRL_A_B_RT_RAMP 0x1a
+#define LM3633_CTRL_A_B_RAMP_CFG 0x1b
+#define LM3633_CTRL_C_E_RT_RAMP 0x1c
+#define LM3633_CTRL_F_H_RT_RAMP 0x1d
+
+#define LM3633_CTRL_A_B_BRT_CFG 0x16
+#define LM3633_CTRL_A_FS_CURR_CFG 0x17
+#define LM3633_CTRL_B_FS_CURR_CFG 0x18
+#define LM3633_PWM_CFG 0x1c
+
+#define LM3633_CTRL_ENABLE 0x2b
+
+#define LM3633_CTRL_A_BRT_LSB 0x40
+#define LM3633_CTRL_A_BRT_MSB 0x41
+#define LM3633_CTRL_B_BRT_LSB 0x42
+#define LM3633_CTRL_B_BRT_MSB 0x43
+#define LM3633_CTRL_C_BRT 0x44
+#define LM3633_CTRL_D_BRT 0x45
+#define LM3633_CTRL_E_BRT 0x46
+#define LM3633_CTRL_F_BRT 0x47
+#define LM3633_CTRL_G_BRT 0x48
+#define LM3633_CTRL_H_BRT 0x49
+
+#define LM3633_SW_RESET BIT(0)
+
+#define LM3633_CTRL_A_EN BIT(0)
+#define LM3633_CTRL_B_EN BIT(1)
+#define LM3633_CTRL_C_EN BIT(2)
+#define LM3633_CTRL_D_EN BIT(3)
+#define LM3633_CTRL_E_EN BIT(4)
+#define LM3633_CTRL_F_EN BIT(5)
+#define LM3633_CTRL_G_EN BIT(6)
+#define LM3633_CTRL_H_EN BIT(7)
+
+#define LM3633_MAX_HVLED_STRINGS 3
+#define LM3633_MAX_LVLED_STRINGS 6
+
+#define LM3633_CONTROL_A 0
+#define LM3633_CONTROL_B 1
+#define LM3633_CONTROL_C 2
+#define LM3633_CONTROL_D 3
+#define LM3633_CONTROL_E 4
+#define LM3633_CONTROL_F 5
+#define LM3633_CONTROL_G 6
+#define LM3633_CONTROL_H 7
+
+#define LM3633_MAX_CONTROL_BANKS 8
+
+#define LM3633_LED_ASSIGNMENT 1
+
+#define LM3633_CTRL_F_EN_MASK 0x07
+#define LM3633_CTRL_EN_OFFSET 2
+
+/**
+ * struct lm3633_led -
+ * @hvled_strings: Array of high voltage LED strings associated to control bank
+ * @lvled_strings: Array of low voltage LED strings associated to a control bank
+ * @label: LED label
+ * @led_dev: LED class device
+ * @priv: Pointer to the device struct
+ * @lmu_data: Register and setting values for common code
+ * @control_bank: Control bank the LED is associated to
+ */
+struct lm3633_led {
+ u32 hvled_strings[LM3633_MAX_HVLED_STRINGS];
+ u32 lvled_strings[LM3633_MAX_LVLED_STRINGS];
+ char label[LED_MAX_NAME_SIZE];
+ struct led_classdev led_dev;
+ struct lm3633 *priv;
+ struct ti_lmu_bank lmu_data;
+ int control_bank;
+};
+
+/**
+ * struct lm3633 -
+ * @enable_gpio - Hardware enable gpio
+ * @regulator - LED supply regulator pointer
+ * @client - Pointer to the I2C client
+ * @regmap - Devices register map
+ * @dev - Pointer to the devices device struct
+ * @lock - Lock for reading/writing the device
+ * @leds - Array of LED strings
+ */
+struct lm3633 {
+ struct gpio_desc *enable_gpio;
+ struct regulator *regulator;
+ struct i2c_client *client;
+ struct regmap *regmap;
+ struct device *dev;
+ struct mutex lock;
+ struct lm3633_led leds[];
+};
+
+static const struct reg_default lm3633_reg_defs[] = {
+ {LM3633_HVLED_OUTPUT_CONFIG, 0x6},
+ {LM3633_LVLED_OUTPUT_CONFIG, 0x36},
+ {LM3633_CTRL_A_RAMP, 0x0},
+ {LM3633_CTRL_B_RAMP, 0x0},
+ {LM3633_CTRL_A_B_RT_RAMP, 0x0},
+ {LM3633_CTRL_A_B_RAMP_CFG, 0x0},
+ {LM3633_CTRL_A_B_BRT_CFG, 0x0},
+ {LM3633_CTRL_A_FS_CURR_CFG, 0x13},
+ {LM3633_CTRL_B_FS_CURR_CFG, 0x13},
+ {LM3633_PWM_CFG, 0xc},
+ {LM3633_CTRL_A_BRT_LSB, 0x0},
+ {LM3633_CTRL_A_BRT_MSB, 0x0},
+ {LM3633_CTRL_B_BRT_LSB, 0x0},
+ {LM3633_CTRL_B_BRT_MSB, 0x0},
+ {LM3633_CTRL_ENABLE, 0x0},
+};
+
+static const struct regmap_config lm3633_regmap_config = {
+ .reg_bits = 8,
+ .val_bits = 8,
+
+ .max_register = LM3633_CTRL_H_BRT,
+ .reg_defaults = lm3633_reg_defs,
+ .num_reg_defaults = ARRAY_SIZE(lm3633_reg_defs),
+ .cache_type = REGCACHE_FLAT,
+};
+
+static int lm3633_brightness_set(struct led_classdev *led_cdev,
+ enum led_brightness brt_val)
+{
+ struct lm3633_led *led = container_of(led_cdev, struct lm3633_led,
+ led_dev);
+ int ctrl_en_val;
+ int ret;
+
+ mutex_lock(&led->priv->lock);
+
+ switch (led->control_bank) {
+ case LM3633_CONTROL_A:
+ ctrl_en_val = LM3633_CTRL_A_EN;
+ break;
+ case LM3633_CONTROL_B:
+ ctrl_en_val = LM3633_CTRL_B_EN;
+ break;
+ case LM3633_CONTROL_C:
+ ctrl_en_val = LM3633_CTRL_C_EN;
+ break;
+ case LM3633_CONTROL_D:
+ ctrl_en_val = LM3633_CTRL_D_EN;
+ break;
+ case LM3633_CONTROL_E:
+ ctrl_en_val = LM3633_CTRL_E_EN;
+ break;
+ case LM3633_CONTROL_F:
+ ctrl_en_val = LM3633_CTRL_F_EN;
+ break;
+ case LM3633_CONTROL_G:
+ ctrl_en_val = LM3633_CTRL_G_EN;
+ break;
+ case LM3633_CONTROL_H:
+ ctrl_en_val = LM3633_CTRL_H_EN;
+ break;
+ default:
+ dev_err(&led->priv->client->dev, "Cannot write brightness\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ if (brt_val == LED_OFF)
+ ret = regmap_update_bits(led->priv->regmap, LM3633_CTRL_ENABLE,
+ ctrl_en_val, ~ctrl_en_val);
+ else
+ ret = regmap_update_bits(led->priv->regmap, LM3633_CTRL_ENABLE,
+ ctrl_en_val, ctrl_en_val);
+
+ ret = ti_lmu_common_set_brightness(&led->lmu_data, brt_val);
+ if (ret)
+ dev_err(&led->priv->client->dev, "Cannot write brightness\n");
+out:
+ mutex_unlock(&led->priv->lock);
+ return ret;
+}
+
+static void lm3633_set_control_bank_regs(struct lm3633_led *led)
+{
+ switch (led->control_bank) {
+ case LM3633_CONTROL_A:
+ led->lmu_data.msb_brightness_reg = LM3633_CTRL_A_BRT_MSB;
+ led->lmu_data.lsb_brightness_reg = LM3633_CTRL_A_BRT_LSB;
+ led->lmu_data.runtime_ramp_reg = LM3633_CTRL_A_RAMP;
+ case LM3633_CONTROL_B:
+ led->lmu_data.msb_brightness_reg = LM3633_CTRL_B_BRT_MSB;
+ led->lmu_data.lsb_brightness_reg = LM3633_CTRL_B_BRT_LSB;
+ led->lmu_data.runtime_ramp_reg = LM3633_CTRL_B_RAMP;
+ break;
+ case LM3633_CONTROL_C:
+ led->lmu_data.msb_brightness_reg = LM3633_CTRL_C_BRT;
+ led->lmu_data.runtime_ramp_reg = LM3633_CTRL_C_E_RT_RAMP;
+ break;
+ case LM3633_CONTROL_D:
+ led->lmu_data.msb_brightness_reg = LM3633_CTRL_D_BRT;
+ led->lmu_data.runtime_ramp_reg = LM3633_CTRL_C_E_RT_RAMP;
+ break;
+ case LM3633_CONTROL_E:
+ led->lmu_data.msb_brightness_reg = LM3633_CTRL_E_BRT;
+ led->lmu_data.runtime_ramp_reg = LM3633_CTRL_C_E_RT_RAMP;
+ break;
+ case LM3633_CONTROL_F:
+ led->lmu_data.msb_brightness_reg = LM3633_CTRL_F_BRT;
+ led->lmu_data.runtime_ramp_reg = LM3633_CTRL_F_H_RT_RAMP;
+ break;
+ case LM3633_CONTROL_G:
+ led->lmu_data.msb_brightness_reg = LM3633_CTRL_G_BRT;
+ led->lmu_data.runtime_ramp_reg = LM3633_CTRL_F_H_RT_RAMP;
+ break;
+ case LM3633_CONTROL_H:
+ led->lmu_data.msb_brightness_reg = LM3633_CTRL_H_BRT;
+ led->lmu_data.runtime_ramp_reg = LM3633_CTRL_F_H_RT_RAMP;
+ break;
+ default:
+ dev_err(&led->priv->client->dev,
+ "Control bank is out of bounds\n");
+ }
+}
+
+static int lm3633_set_control_bank(struct lm3633 *priv)
+{
+ u8 control_bank_config = 0;
+ struct lm3633_led *led;
+ int ret, i;
+
+ led = &priv->leds[0];
+ if (led->control_bank == LM3633_CONTROL_A) {
+ lm3633_set_control_bank_regs(led);
+ led = &priv->leds[1];
+ }
+
+ if (led->control_bank >= LM3633_CONTROL_C)
+ return 0;
+
+ lm3633_set_control_bank_regs(led);
+ for (i = 0; i < LM3633_MAX_HVLED_STRINGS; i++)
+ if (led->hvled_strings[i] == LM3633_LED_ASSIGNMENT)
+ control_bank_config |= 1 << i;
+
+ ret = regmap_write(priv->regmap, LM3633_HVLED_OUTPUT_CONFIG,
+ control_bank_config);
+ if (ret)
+ dev_err(&priv->client->dev, "Cannot write OUTPUT config\n");
+
+ return ret;
+}
+
+static int lm3633_set_lvled_control_bank(struct lm3633 *priv)
+{
+ u8 control_bank_config = 0;
+ struct lm3633_led *led;
+ int ret, i;
+
+ for (i = 0; i <= LM3633_MAX_CONTROL_BANKS; i++) {
+ led = &priv->leds[i];
+ if (led) {
+ if (led->control_bank < LM3633_CONTROL_C)
+ continue;
+
+ if (led->lvled_strings[0]) {
+ if (led->control_bank == LM3633_CONTROL_C)
+ control_bank_config = 0x0;
+ else if (led->control_bank == LM3633_CONTROL_F)
+ control_bank_config &= LM3633_CTRL_F_EN_MASK;
+ else
+ control_bank_config |= 1 << (led->control_bank - LM3633_CTRL_EN_OFFSET);
+ }
+ } else
+ continue;
+
+ lm3633_set_control_bank_regs(led);
+ }
+
+ ret = regmap_write(priv->regmap, LM3633_LVLED_OUTPUT_CONFIG,
+ control_bank_config);
+ if (ret)
+ dev_err(&priv->client->dev, "Cannot write OUTPUT config\n");
+
+ return ret;
+}
+
+static int lm3633_init(struct lm3633 *priv)
+{
+ struct lm3633_led *led;
+ int i, ret;
+
+ if (priv->enable_gpio) {
+ gpiod_direction_output(priv->enable_gpio, 1);
+ } else {
+ ret = regmap_write(priv->regmap, LM3633_RESET, LM3633_SW_RESET);
+ if (ret) {
+ dev_err(&priv->client->dev,
+ "Cannot reset the device\n");
+ goto out;
+ }
+ }
+
+ ret = regmap_write(priv->regmap, LM3633_CTRL_ENABLE, 0x0);
+ if (ret) {
+ dev_err(&priv->client->dev, "Cannot write ctrl enable\n");
+ goto out;
+ }
+
+ ret = lm3633_set_control_bank(priv);
+ if (ret)
+ dev_err(&priv->client->dev, "Setting the CRTL bank failed\n");
+
+ ret = lm3633_set_lvled_control_bank(priv);
+ if (ret)
+ dev_err(&priv->client->dev,
+ "Setting the lvled CRTL bank failed\n");
+
+ for (i = 0; i < LM3633_MAX_CONTROL_BANKS; i++) {
+ led = &priv->leds[i];
+ if (led->lmu_data.runtime_ramp_reg) {
+ ti_lmu_common_set_ramp(&led->lmu_data);
+ if (ret)
+ dev_err(&priv->client->dev,
+ "Setting the ramp rate failed\n");
+ }
+ }
+out:
+ return ret;
+}
+
+static int lm3633_parse_hvled_sources(struct fwnode_handle *child,
+ struct lm3633_led *led)
+{
+ struct lm3633 *priv = led->priv;
+ int ret;
+
+ ret = fwnode_property_read_u32_array(child, "led-sources",
+ led->hvled_strings,
+ LM3633_MAX_HVLED_STRINGS);
+
+ if (ret)
+ dev_err(&priv->client->dev, "Cannot write OUTPUT config\n");
+
+ return ret;
+}
+
+static int lm3633_parse_lvled_sources(struct fwnode_handle *child,
+ struct lm3633_led *led)
+{
+ struct lm3633 *priv = led->priv;
+ int ret;
+
+ ret = fwnode_property_read_u32_array(child, "led-sources",
+ led->lvled_strings, 1);
+ if (ret)
+ dev_err(&priv->client->dev, "Cannot write OUTPUT config\n");
+
+ led->lmu_data.max_brightness = MAX_BRIGHTNESS_8BIT;
+
+ return 0;
+}
+
+static int lm3633_probe_dt(struct lm3633 *priv)
+{
+ struct fwnode_handle *child = NULL;
+ struct lm3633_led *led;
+ const char *name;
+ int control_bank;
+ size_t i = 0;
+ int ret;
+
+ priv->enable_gpio = devm_gpiod_get_optional(&priv->client->dev,
+ "enable", GPIOD_OUT_LOW);
+ if (IS_ERR(priv->enable_gpio)) {
+ ret = PTR_ERR(priv->enable_gpio);
+ dev_err(&priv->client->dev, "Failed to get enable gpio: %d\n",
+ ret);
+ return ret;
+ }
+
+ priv->regulator = devm_regulator_get(&priv->client->dev, "vled");
+ if (IS_ERR(priv->regulator))
+ priv->regulator = NULL;
+
+ device_for_each_child_node(priv->dev, child) {
+ ret = fwnode_property_read_u32(child, "reg", &control_bank);
+ if (ret) {
+ dev_err(&priv->client->dev, "reg property missing\n");
+ fwnode_handle_put(child);
+ goto child_out;
+ }
+
+ if (control_bank > LM3633_MAX_CONTROL_BANKS) {
+ dev_err(&priv->client->dev,
+ "reg property is invalid\n");
+ ret = -EINVAL;
+ fwnode_handle_put(child);
+ goto child_out;
+ }
+
+ led = &priv->leds[i];
+ led->control_bank = control_bank;
+ led->lmu_data.bank_id = control_bank;
+ led->lmu_data.regmap = priv->regmap;
+ led->lmu_data.enable_reg = LM3633_CTRL_ENABLE;
+
+ if (control_bank > LM3633_CONTROL_B)
+ lm3633_parse_lvled_sources(child, led);
+ else
+ lm3633_parse_hvled_sources(child, led);
+
+ ret = ti_lmu_common_get_ramp_params(&priv->client->dev,
+ child, &led->lmu_data);
+ if (ret)
+ dev_warn(&priv->client->dev,
+ "runtime-ramp properties missing\n");
+
+ fwnode_property_read_string(child, "linux,default-trigger",
+ &led->led_dev.default_trigger);
+
+ ret = fwnode_property_read_string(child, "label", &name);
+ if (ret)
+ snprintf(led->label, sizeof(led->label),
+ "%s::", priv->client->name);
+ else
+ snprintf(led->label, sizeof(led->label),
+ "%s:%s", priv->client->name, name);
+
+ led->priv = priv;
+ led->led_dev.name = led->label;
+ led->led_dev.brightness_set_blocking = lm3633_brightness_set;
+
+ ret = devm_led_classdev_register(priv->dev, &led->led_dev);
+ if (ret) {
+ dev_err(&priv->client->dev, "led register err: %d\n",
+ ret);
+ fwnode_handle_put(child);
+ goto child_out;
+ }
+
+ i++;
+ }
+
+child_out:
+ return ret;
+}
+
+static int lm3633_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct lm3633 *led;
+ int count;
+ int ret;
+
+ count = device_get_child_node_count(&client->dev);
+ if (!count) {
+ dev_err(&client->dev, "LEDs are not defined in device tree!");
+ return -ENODEV;
+ }
+
+ led = devm_kzalloc(&client->dev, struct_size(led, leds, count),
+ GFP_KERNEL);
+ if (!led)
+ return -ENOMEM;
+
+ mutex_init(&led->lock);
+ i2c_set_clientdata(client, led);
+
+ led->client = client;
+ led->dev = &client->dev;
+ led->regmap = devm_regmap_init_i2c(client, &lm3633_regmap_config);
+ if (IS_ERR(led->regmap)) {
+ ret = PTR_ERR(led->regmap);
+ dev_err(&client->dev, "Failed to allocate register map: %d\n",
+ ret);
+ return ret;
+ }
+
+ ret = lm3633_probe_dt(led);
+ if (ret)
+ return ret;
+
+ return lm3633_init(led);
+}
+
+static int lm3633_remove(struct i2c_client *client)
+{
+ struct lm3633 *led = i2c_get_clientdata(client);
+ int ret;
+
+ ret = regmap_write(led->regmap, LM3633_CTRL_ENABLE, 0);
+ if (ret) {
+ dev_err(&led->client->dev, "Failed to disable the device\n");
+ return ret;
+ }
+
+ if (led->enable_gpio)
+ gpiod_direction_output(led->enable_gpio, 0);
+
+ if (led->regulator) {
+ ret = regulator_disable(led->regulator);
+ if (ret)
+ dev_err(&led->client->dev,
+ "Failed to disable regulator\n");
+ }
+
+ mutex_destroy(&led->lock);
+
+ return 0;
+}
+
+static const struct i2c_device_id lm3633_id[] = {
+ { "lm3633", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, lm3633_id);
+
+static const struct of_device_id of_lm3633_leds_match[] = {
+ { .compatible = "ti,lm3633", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, of_lm3633_leds_match);
+
+static struct i2c_driver lm3633_driver = {
+ .driver = {
+ .name = "lm3633",
+ .of_match_table = of_lm3633_leds_match,
+ },
+ .probe = lm3633_probe,
+ .remove = lm3633_remove,
+ .id_table = lm3633_id,
+};
+module_i2c_driver(lm3633_driver);
+
+MODULE_DESCRIPTION("Texas Instruments LM3633 LED driver");
+MODULE_AUTHOR("Dan Murphy <dmurphy@xxxxxx>");
+MODULE_LICENSE("GPL v2");
--
2.19.0

Next message: Dan Murphy: "[PATCH v3 8/9] dt-bindings: leds: Add support for the LM3633"
Previous message: Thierry Reding: "Re: [PATCH V2 5/5] arm64: dts: tegra210: Add power-domains for xHCI"
In reply to: Dan Murphy: "[PATCH v3 1/9] leds: add TI LMU backlight driver"
Next in thread: Dan Murphy: "[PATCH v3 8/9] dt-bindings: leds: Add support for the LM3633"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]