From: KancyJoe <[email protected]>

Implement support for the Silergy SY7758 6-channel High Efficiency LED
Driver used for backlight brightness control in the Ayaneo Pocket S2
dual-DSI panel.

Signed-off-by: KancyJoe <[email protected]>
Signed-off-by: Neil Armstrong <[email protected]>
---
 drivers/video/backlight/Kconfig  |   8 ++
 drivers/video/backlight/Makefile |   1 +
 drivers/video/backlight/sy7758.c | 259 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 268 insertions(+)

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index a7a3fbaf7c29..052ac80c8213 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -207,6 +207,14 @@ config BACKLIGHT_KTZ8866
                Say Y to enable the backlight driver for the Kinetic KTZ8866
                found in Xiaomi Mi Pad 5 series.
 
+config BACKLIGHT_SY7758
+       tristate "Backlight Driver for Silergy SY7758"
+       depends on I2C
+       select REGMAP_I2C
+       help
+         Say Y to enable the backlight driver for the Silergy SY7758
+         backlight controller found in Ayaneo Socket S2.
+
 config BACKLIGHT_LM3533
        tristate "Backlight Driver for LM3533"
        depends on MFD_LM3533
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index 794820a98ed4..39ef588b1cf2 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -56,6 +56,7 @@ obj-$(CONFIG_BACKLIGHT_PWM)           += pwm_bl.o
 obj-$(CONFIG_BACKLIGHT_QCOM_WLED)      += qcom-wled.o
 obj-$(CONFIG_BACKLIGHT_RT4831)         += rt4831-backlight.o
 obj-$(CONFIG_BACKLIGHT_SAHARA)         += kb3886_bl.o
+obj-$(CONFIG_BACKLIGHT_SY7758)         += sy7758.o
 obj-$(CONFIG_BACKLIGHT_SKY81452)       += sky81452-backlight.o
 obj-$(CONFIG_BACKLIGHT_TPS65217)       += tps65217_bl.o
 obj-$(CONFIG_BACKLIGHT_WM831X)         += wm831x_bl.o
diff --git a/drivers/video/backlight/sy7758.c b/drivers/video/backlight/sy7758.c
new file mode 100644
index 000000000000..a6087e687b64
--- /dev/null
+++ b/drivers/video/backlight/sy7758.c
@@ -0,0 +1,259 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Silergy SY7758 6-channel High Efficiency LED Driver
+ *
+ * Copyright (C) 2025 Kancy Joe <[email protected]>
+ * Copyright (C) 2026 Linaro Limited
+ * Author: Neil Armstrong <[email protected]>
+ */
+#include <linux/backlight.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/of.h>
+#include <linux/err.h>
+#include <linux/bits.h>
+#include <linux/regmap.h>
+#include <linux/bitfield.h>
+#include <linux/gpio/consumer.h>
+#include <linux/regulator/consumer.h>
+
+#define DEFAULT_BRIGHTNESS     1024
+#define MAX_BRIGHTNESS         4080
+#define REG_MAX                        0xAE
+
+/* Registers */
+#define REG_DEV_CTL            0x01
+#define REG_DEV_ID             0x03
+#define REG_BRT_12BIT_L                0x10
+#define REG_BRT_12BIT_H                0x11
+
+/* OTP memory */
+#define REG_OTP_CFG0           0xA0
+#define REG_OTP_CFG1           0xA1
+#define REG_OTP_CFG2           0xA2
+#define REG_OTP_CFG5           0xA5
+#define REG_OTP_CFG9           0xA9
+
+/* Fields */
+#define BIT_DEV_CTL_FAST       BIT(7)
+#define MSK_DEV_CTL_BRT_MODE   GENMASK(2, 1)
+#define BIT_DEV_CTL_BL_CTLB    BIT(0)
+
+#define MSK_BRT_12BIT_L                GENMASK(7, 0)
+#define MSK_BRT_12BIT_H                GENMASK(3, 0)
+#define MSK_LED_ENABLE         GENMASK(5, 0)
+
+#define MSK_CFG0_CURRENT_LOW   GENMASK(7, 0)
+
+#define BIT_CFG1_PDET_STDBY    BIT(7)
+#define MSK_CFG1_CURRENT_MAX   GENMASK(6, 4)
+#define MSK_CFG1_CURRENT_HIGH  GENMASK(3, 0)
+
+#define BIT_CFG2_UVLO_EN       BIT(5)
+#define BIT_CFG2_UVLO_TH       BIT(4)
+#define BIT_CFG2_BL_ON         BIT(3)
+#define BIT_CFG2_ISET_EN       BIT(2)
+#define BIT_CFG2_BST_ESET_EN   BIT(1)
+
+#define BIT_CFG5_PWM_DIRECT    BIT(7)
+#define MSK_CFG5_PS_MODE       GENMASK(6, 4)
+#define MSK_CFG5_PWM_FREQ      GENMASK(3, 0)
+
+#define MSK_CFG9_VBST_MAX      GENMASK(7, 5)
+#define BIT_CFG9_JUMP_EN       BIT(4)
+#define MSK_CFG9_JUMP_TH       GENMASK(3, 2)
+#define MSK_CFG9_JUMP_VOLTAGE  GENMASK(1, 0)
+
+struct sy7758 {
+       struct i2c_client *client;
+       struct regmap *regmap;
+       struct gpio_desc *gpio;
+       struct backlight_device *bl;
+};
+
+static const struct regmap_config sy7758_regmap_config = {
+       .reg_bits = 8,
+       .val_bits = 8,
+       .max_register = REG_MAX,
+};
+
+static int sy7758_backlight_update_status(struct backlight_device 
*backlight_dev)
+{
+       struct sy7758 *sydev = bl_get_data(backlight_dev);
+       unsigned int brightness = backlight_get_brightness(backlight_dev);
+       int ret;
+
+       ret = regmap_write(sydev->regmap, REG_BRT_12BIT_L,
+                          FIELD_PREP(MSK_BRT_12BIT_L,
+                                     brightness & 0xff));
+       if (ret)
+               return ret;
+
+       ret = regmap_write(sydev->regmap, REG_BRT_12BIT_H,
+                          FIELD_PREP(MSK_BRT_12BIT_H,
+                                     (brightness >> 8) & 0xf));
+       if (ret)
+               return ret;
+
+       return 0;
+}
+
+static const struct backlight_ops sy7758_backlight_ops = {
+       .options = BL_CORE_SUSPENDRESUME,
+       .update_status = sy7758_backlight_update_status,
+};
+
+static int sy7758_init(struct sy7758 *sydev)
+{
+       int ret = 0;
+
+       ret = regmap_write(sydev->regmap, REG_DEV_CTL,
+                          BIT_DEV_CTL_FAST | BIT_DEV_CTL_BL_CTLB |
+                          FIELD_PREP(MSK_DEV_CTL_BRT_MODE, 2));
+       if (ret)
+               return ret;
+
+       ret = regmap_write(sydev->regmap, REG_BRT_12BIT_L,
+                          FIELD_PREP(MSK_BRT_12BIT_L,
+                                     DEFAULT_BRIGHTNESS & 0xff));
+       if (ret)
+               return ret;
+
+       ret = regmap_write(sydev->regmap, REG_BRT_12BIT_H,
+                          FIELD_PREP(MSK_BRT_12BIT_H,
+                                     (DEFAULT_BRIGHTNESS >> 8)));
+       if (ret)
+               return ret;
+
+       ret = regmap_write(sydev->regmap, REG_OTP_CFG5,
+                          FIELD_PREP(MSK_CFG5_PS_MODE, 6) |
+                          FIELD_PREP(MSK_CFG5_PWM_FREQ, 4));
+       if (ret)
+               return ret;
+
+       ret = regmap_write(sydev->regmap, REG_OTP_CFG0,
+                          FIELD_PREP(MSK_CFG0_CURRENT_LOW, 85));
+       if (ret)
+               return ret;
+
+       ret = regmap_write(sydev->regmap, REG_OTP_CFG1,
+                          BIT_CFG1_PDET_STDBY |
+                          FIELD_PREP(MSK_CFG1_CURRENT_MAX, 1) |
+                          FIELD_PREP(MSK_CFG1_CURRENT_HIGH, 10));
+       if (ret)
+               return ret;
+
+       ret = regmap_write(sydev->regmap, REG_OTP_CFG9,
+                          FIELD_PREP(MSK_CFG9_VBST_MAX, 4));
+       if (ret)
+               return ret;
+
+       ret = regmap_write(sydev->regmap, REG_OTP_CFG2,
+                          BIT_CFG2_BL_ON | BIT_CFG2_UVLO_EN);
+       if (ret)
+               return ret;
+
+       return 0;
+}
+
+static int sy7758_probe(struct i2c_client *client)
+{
+       struct backlight_properties props = { };
+       struct device *dev = &client->dev;
+       struct sy7758 *sydev;
+       unsigned int dev_id;
+       int ret;
+
+       sydev = devm_kzalloc(dev, sizeof(*sydev), GFP_KERNEL);
+       if (!sydev)
+               return -ENOMEM;
+
+       i2c_set_clientdata(client, sydev);
+
+       /* Initialize regmap */
+       sydev->client = client;
+       sydev->regmap = devm_regmap_init_i2c(client, &sy7758_regmap_config);
+       if (IS_ERR(sydev->regmap))
+               return dev_err_probe(dev, PTR_ERR(sydev->regmap),
+                                    "failed to init regmap\n");
+
+       /* Get and enable regulators */
+       ret = devm_regulator_get_enable(dev, "vddio");
+       if (ret)
+               return dev_err_probe(dev, ret, "failed to get regulator\n");
+
+       fsleep(100);
+
+       /* Get enable GPIO and set to high */
+       sydev->gpio = devm_gpiod_get(dev, "enable", GPIOD_OUT_HIGH);
+       if (IS_ERR(sydev->gpio))
+               return dev_err_probe(dev, PTR_ERR(sydev->gpio),
+                                    "failed to get enable GPIO\n");
+
+       /* Let some time for HW to settle */
+       fsleep(10000);
+
+       /* try read and check device id */
+       ret = regmap_read(sydev->regmap, REG_DEV_ID, &dev_id);
+       if (ret < 0)
+               return dev_err_probe(dev, ret, "failed to read device id\n");
+       if (dev_id != 0x63) {
+               dev_err(dev, "unexpected device id: 0x%02x\n", dev_id);
+               return -ENODEV;
+       }
+
+       /* Initialize and set default brightness */
+       ret = sy7758_init(sydev);
+       if (ret)
+               return ret;
+
+       props.type = BACKLIGHT_RAW;
+       props.max_brightness = MAX_BRIGHTNESS;
+       props.brightness = DEFAULT_BRIGHTNESS;
+       props.scale = BACKLIGHT_SCALE_LINEAR;
+
+       sydev->bl = devm_backlight_device_register(dev, "sy7758-backlight",
+                                                  dev, sydev, 
&sy7758_backlight_ops,
+                                                  &props);
+       if (IS_ERR(sydev->bl))
+               return dev_err_probe(dev, PTR_ERR(sydev->bl),
+                                    "failed to register backlight device\n");
+
+       return backlight_update_status(sydev->bl);
+}
+
+static void sy7758_remove(struct i2c_client *client)
+{
+       struct sy7758 *sydev = i2c_get_clientdata(client);
+
+       backlight_disable(sydev->bl);
+}
+
+static const struct i2c_device_id sy7758_ids[] = {
+       { "sy7758" },
+       { }
+};
+MODULE_DEVICE_TABLE(i2c, sy7758_ids);
+
+static const struct of_device_id sy7758_match_table[] = {
+       { .compatible = "silergy,sy7758", },
+       { },
+};
+MODULE_DEVICE_TABLE(of, sy7758_match_table);
+
+static struct i2c_driver sy7758_driver = {
+       .driver = {
+               .name = "sy7758",
+               .of_match_table = sy7758_match_table,
+       },
+       .probe = sy7758_probe,
+       .remove = sy7758_remove,
+       .id_table = sy7758_ids,
+};
+
+module_i2c_driver(sy7758_driver);
+
+MODULE_DESCRIPTION("Silergy SY7758 Backlight Driver");
+MODULE_AUTHOR("Kancy Joe <[email protected]>");
+MODULE_AUTHOR("Neil Armstrong <[email protected]>");
+MODULE_LICENSE("GPL");

-- 
2.34.1

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