text: // SPDX-License-Identifier: GPL-2.0-only
  /*
   * Parade PS8622 eDP/LVDS bridge driver
   *
   * Copyright (C) 2014 Google, Inc.
   */
  
  #include <linux/backlight.h>
  #include <linux/delay.h>
  #include <linux/err.h>
  #include <linux/gpio/consumer.h>
  #include <linux/i2c.h>
  #include <linux/module.h>
  #include <linux/of.h>
  #include <linux/of_device.h>
  #include <linux/pm.h>
  #include <linux/regulator/consumer.h>
  
  #include <drm/drm_atomic_helper.h>
  #include <drm/drm_bridge.h>
  #include <drm/drm_crtc.h>
  #include <drm/drm_of.h>
  #include <drm/drm_panel.h>
  #include <drm/drm_print.h>
  #include <drm/drm_probe_helper.h>
  
  /* Brightness scale on the Parade chip */
  #define PS8622_MAX_BRIGHTNESS 0xff
  
  /* Timings taken from the version 1.7 datasheet for the PS8622/PS8625 */
  #define PS8622_POWER_RISE_T1_MIN_US 10
  #define PS8622_POWER_RISE_T1_MAX_US 10000
  #define PS8622_RST_HIGH_T2_MIN_US 3000
  #define PS8622_RST_HIGH_T2_MAX_US 30000
  #define PS8622_PWMO_END_T12_MS 200
  #define PS8622_POWER_FALL_T16_MAX_US 10000
  #define PS8622_POWER_OFF_T17_MS 500
  
  #if ((PS8622_RST_HIGH_T2_MIN_US + PS8622_POWER_RISE_T1_MAX_US) > \
  	(PS8622_RST_HIGH_T2_MAX_US + PS8622_POWER_RISE_T1_MIN_US))
  #error "T2.min + T1.max must be less than T2.max + T1.min"
  #endif
  
  struct ps8622_bridge {
  	struct drm_connector connector;
  	struct i2c_client *client;
  	struct drm_bridge bridge;
  	struct drm_panel *panel;
  	struct regulator *v12;
  	struct backlight_device *bl;
  
  	struct gpio_desc *gpio_slp;
  	struct gpio_desc *gpio_rst;
  
  	u32 max_lane_count;
  	u32 lane_count;
  
  	bool enabled;
  };
  
  static inline struct ps8622_bridge *
  		bridge_to_ps8622(struct drm_bridge *bridge)
  {
  	return container_of(bridge, struct ps8622_bridge, bridge);
  }
  
  static inline struct ps8622_bridge *
  		connector_to_ps8622(struct drm_connector *connector)
  {
  	return container_of(connector, struct ps8622_bridge, connector);
  }
  
  static int ps8622_set(struct i2c_client *client, u8 page, u8 reg, u8 val)
  {
  	int ret;
  	struct i2c_adapter *adap = client->adapter;
  	struct i2c_msg msg;
  	u8 data[] = {reg, val};
  
  	msg.addr = client->addr + page;
  	msg.flags = 0;
  	msg.len = sizeof(data);
  	msg.buf = data;
  
  	ret = i2c_transfer(adap, &msg, 1);
  	if (ret != 1)
  		pr_warn("PS8622 I2C write (0x%02x,0x%02x,0x%02x) failed: %d\n",
  			client->addr + page, reg, val, ret);
  	return !(ret == 1);
  }
  
  static int ps8622_send_config(struct ps8622_bridge *ps8622)
  {
  	struct i2c_client *cl = ps8622->client;
  	int err = 0;
  
  	/* HPD low */
  	err = ps8622_set(cl, 0x02, 0xa1, 0x01);
  	if (err)
  		goto error;
  
  	/* SW setting: [1:0] SW output 1.2V voltage is lower to 96% */
  	err = ps8622_set(cl, 0x04, 0x14, 0x01);
  	if (err)
  		goto error;
  
  	/* RCO SS setting: [5:4] = b01 0.5%, b10 1%, b11 1.5% */
  	err = ps8622_set(cl, 0x04, 0xe3, 0x20);
  	if (err)
  		goto error;
  
  	/* [7] RCO SS enable */
  	err = ps8622_set(cl, 0x04, 0xe2, 0x80);
  	if (err)
  		goto error;
  
  	/* RPHY Setting
  	 * [3:2] CDR tune wait cycle before measure for fine tune
  	 * b00: 1us b01: 0.5us b10:2us, b11: 4us
  	 */
  	err = ps8622_set(cl, 0x04, 0x8a, 0x0c);
  	if (err)
  		goto error;
  
  	/* [3] RFD always on */
  	err = ps8622_set(cl, 0x04, 0x89, 0x08);
  	if (err)
  		goto error;
  
  	/* CTN lock in/out: 20000ppm/80000ppm. Lock out 2 times. */
  	err = ps8622_set(cl, 0x04, 0x71, 0x2d);
  	if (err)
  		goto error;
  
  	/* 2.7G CDR settings: NOF=40LSB for HBR CDR  setting */
  	err = ps8622_set(cl, 0x04, 0x7d, 0x07);
  	if (err)
  		goto error;
  
  	/* [1:0] Fmin=+4bands */
  	err = ps8622_set(cl, 0x04, 0x7b, 0x00);
  	if (err)
  		goto error;
  
  	/* [7:5] DCO_FTRNG=+-40% */
  	err = ps8622_set(cl, 0x04, 0x7a, 0xfd);
  	if (err)
  		goto error;
  
  	/* 1.62G CDR settings: [5:2]NOF=64LSB [1:0]DCO scale is 2/5 */
  	err = ps8622_set(cl, 0x04, 0xc0, 0x12);
  	if (err)
  		goto error;
  
  	/* Gitune=-37% */
  	err = ps8622_set(cl, 0x04, 0xc1, 0x92);
  	if (err)
  		goto error;
  
  	/* Fbstep=100% */
  	err = ps8622_set(cl, 0x04, 0xc2, 0x1c);
  	if (err)
  		goto error;
  
  	/* [7] LOS signal disable */
  	err = ps8622_set(cl, 0x04, 0x32, 0x80);
  	if (err)
  		goto error;
  
  	/* RPIO Setting: [7:4] LVDS driver bias current : 75% (250mV swing) */
  	err = ps8622_set(cl, 0x04, 0x00, 0xb0);
  	if (err)
  		goto error;
  
  	/* [7:6] Right-bar GPIO output strength is 8mA */
  	err = ps8622_set(cl, 0x04, 0x15, 0x40);
  	if (err)
  		goto error;
  
  	/* EQ Training State Machine Setting, RCO calibration start */
  	err = ps8622_set(cl, 0x04, 0x54, 0x10);
  	if (err)
  		goto error;
  
  	/* Logic, needs more than 10 I2C command */
  	/* [4:0] MAX_LANE_COUNT set to max supported lanes */
  	err = ps8622_set(cl, 0x01, 0x02, 0x80 | ps8622->max_lane_count);
  	if (err)
  		goto error;
  
  	/* [4:0] LANE_COUNT_SET set to chosen lane count */
  	err = ps8622_set(cl, 0x01, 0x21, 0x80 | ps8622->lane_count);
  	if (err)
  		goto error;
  
  	err = ps8622_set(cl, 0x00, 0x52, 0x20);
  	if (err)
  		goto error;
  
  	/* HPD CP toggle enable */
  	err = ps8622_set(cl, 0x00, 0xf1, 0x03);
  	if (err)
  		goto error;
  
  	err = ps8622_set(cl, 0x00, 0x62, 0x41);
  	if (err)
  		goto error;
  
  	/* Counter number, add 1ms counter delay */
  	err = ps8622_set(cl, 0x00, 0xf6, 0x01);
  	if (err)
  		goto error;
  
  	/* [6]PWM function control by DPCD0040f[7], default is PWM block */
  	err = ps8622_set(cl, 0x00, 0x77, 0x06);
  	if (err)
  		goto error;
  
  	/* 04h Adjust VTotal toleranceto fix the 30Hz no display issue */
  	err = ps8622_set(cl, 0x00, 0x4c, 0x04);
  	if (err)
  		goto error;
  
  	/* DPCD00400='h00, Parade OUI ='h001cf8 */
  	err = ps8622_set(cl, 0x01, 0xc0, 0x00);
  	if (err)
  		goto error;
  
  	/* DPCD00401='h1c */
  	err = ps8622_set(cl, 0x01, 0xc1, 0x1c);
  	if (err)
  		goto error;
  
  	/* DPCD00402='hf8 */
  	err = ps8622_set(cl, 0x01, 0xc2, 0xf8);
  	if (err)
  		goto error;
  
  	/* DPCD403~408 = ASCII code, D2SLV5='h4432534c5635 */
  	err = ps8622_set(cl, 0x01, 0xc3, 0x44);
  	if (err)
  		goto error;
  
  	/* DPCD404 */
  	err = ps8622_set(cl, 0x01, 0xc4, 0x32);
  	if (err)
  		goto error;
  
  	/* DPCD405 */
  	err = ps8622_set(cl, 0x01, 0xc5, 0x53);
  	if (err)
  		goto error;
  
  	/* DPCD406 */
  	err = ps8622_set(cl, 0x01, 0xc6, 0x4c);
  	if (err)
  		goto error;
  
  	/* DPCD407 */
  	err = ps8622_set(cl, 0x01, 0xc7, 0x56);
  	if (err)
  		goto error;
  
  	/* DPCD408 */
  	err = ps8622_set(cl, 0x01, 0xc8, 0x35);
  	if (err)
  		goto error;
  
  	/* DPCD40A, Initial Code major revision '01' */
  	err = ps8622_set(cl, 0x01, 0xca, 0x01);
  	if (err)
  		goto error;
  
  	/* DPCD40B, Initial Code minor revision '05' */
  	err = ps8622_set(cl, 0x01, 0xcb, 0x05);
  	if (err)
  		goto error;
  
  
  	if (ps8622->bl) {
  		/* DPCD720, internal PWM */
  		err = ps8622_set(cl, 0x01, 0xa5, 0xa0);
  		if (err)
  			goto error;
  
  		/* FFh for 100% brightness, 0h for 0% brightness */
  		err = ps8622_set(cl, 0x01, 0xa7,
  				ps8622->bl->props.brightness);
  		if (err)
  			goto error;
  	} else {
  		/* DPCD720, external PWM */
  		err = ps8622_set(cl, 0x01, 0xa5, 0x80);
  		if (err)
  			goto error;
  	}
  
  	/* Set LVDS output as 6bit-VESA mapping, single LVDS channel */
  	err = ps8622_set(cl, 0x01, 0xcc, 0x13);
  	if (err)
  		goto error;
  
  	/* Enable SSC set by register */
  	err = ps8622_set(cl, 0x02, 0xb1, 0x20);
  	if (err)
  		goto error;
  
  	/* Set SSC enabled and +/-1% central spreading */
  	err = ps8622_set(cl, 0x04, 0x10, 0x16);
  	if (err)
  		goto error;
  
  	/* Logic end */
  	/* MPU Clock source: LC => RCO */
  	err = ps8622_set(cl, 0x04, 0x59, 0x60);
  	if (err)
  		goto error;
  
  	/* LC -> RCO */
  	err = ps8622_set(cl, 0x04, 0x54, 0x14);
  	if (err)
  		goto error;
  
  	/* HPD high */
  	err = ps8622_set(cl, 0x02, 0xa1, 0x91);
  
  error:
  	return err ? -EIO : 0;
  }
  
  static int ps8622_backlight_update(struct backlight_device *bl)
  {
  	struct ps8622_bridge *ps8622 = dev_get_drvdata(&bl->dev);
  	int ret, brightness = bl->props.brightness;
  
  	if (bl->props.power != FB_BLANK_UNBLANK ||
  	    bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
  		brightness = 0;
  
  	if (!ps8622->enabled)
  		return -EINVAL;
  
  	ret = ps8622_set(ps8622->client, 0x01, 0xa7, brightness);
  
  	return ret;
  }
  
  static const struct backlight_ops ps8622_backlight_ops = {
  	.update_status	= ps8622_backlight_update,
  };
  
  static void ps8622_pre_enable(struct drm_bridge *bridge)
  {
  	struct ps8622_bridge *ps8622 = bridge_to_ps8622(bridge);
  	int ret;
  
  	if (ps8622->enabled)
  		return;
  
  	gpiod_set_value(ps8622->gpio_rst, 0);
  
  	if (ps8622->v12) {
  		ret = regulator_enable(ps8622->v12);
  		if (ret)
  			DRM_ERROR("fails to enable ps8622->v12");
  	}
  
  	if (drm_panel_prepare(ps8622->panel)) {
  		DRM_ERROR("failed to prepare panel\n");
  		return;
  	}
  
  	gpiod_set_value(ps8622->gpio_slp, 1);
  
  	/*
  	 * T1 is the range of time that it takes for the power to rise after we
  	 * enable the lcd/ps8622 fet. T2 is the range of time in which the
  	 * data sheet specifies we should deassert the reset pin.
  	 *
  	 * If it takes T1.max for the power to rise, we need to wait atleast
  	 * T2.min before deasserting the reset pin. If it takes T1.min for the
  	 * power to rise, we need to wait at most T2.max before deasserting the
  	 * reset pin.
  	 */
  	usleep_range(PS8622_RST_HIGH_T2_MIN_US + PS8622_POWER_RISE_T1_MAX_US,
  		     PS8622_RST_HIGH_T2_MAX_US + PS8622_POWER_RISE_T1_MIN_US);
  
  	gpiod_set_value(ps8622->gpio_rst, 1);
  
  	/* wait 20ms after RST high */
  	usleep_range(20000, 30000);
  
  	ret = ps8622_send_config(ps8622);
  	if (ret) {
  		DRM_ERROR("Failed to send config to bridge (%d)\n", ret);
  		return;
  	}
  
  	ps8622->enabled = true;
  }
  
  static void ps8622_enable(struct drm_bridge *bridge)
  {
  	struct ps8622_bridge *ps8622 = bridge_to_ps8622(bridge);
  
  	if (drm_panel_enable(ps8622->panel)) {
  		DRM_ERROR("failed to enable panel\n");
  		return;
  	}
  }
  
  static void ps8622_disable(struct drm_bridge *bridge)
  {
  	struct ps8622_bridge *ps8622 = bridge_to_ps8622(bridge);
  
  	if (drm_panel_disable(ps8622->panel)) {
  		DRM_ERROR("failed to disable panel\n");
  		return;
  	}
  	msleep(PS8622_PWMO_END_T12_MS);
  }
  
  static void ps8622_post_disable(struct drm_bridge *bridge)
  {
  	struct ps8622_bridge *ps8622 = bridge_to_ps8622(bridge);
  
  	if (!ps8622->enabled)
  		return;
  
  	ps8622->enabled = false;
  
  	/*
  	 * This doesn't matter if the regulators are turned off, but something
  	 * else might keep them on. In that case, we want to assert the slp gpio
  	 * to lower power.
  	 */
  	gpiod_set_value(ps8622->gpio_slp, 0);
  
  	if (drm_panel_unprepare(ps8622->panel)) {
  		DRM_ERROR("failed to unprepare panel\n");
  		return;
  	}
  
  	if (ps8622->v12)
  		regulator_disable(ps8622->v12);
  
  	/*
  	 * Sleep for at least the amount of time that it takes the power rail to
  	 * fall to prevent asserting the rst gpio from doing anything.
  	 */
  	usleep_range(PS8622_POWER_FALL_T16_MAX_US,
  		     2 * PS8622_POWER_FALL_T16_MAX_US);
  	gpiod_set_value(ps8622->gpio_rst, 0);
  
  	msleep(PS8622_POWER_OFF_T17_MS);
  }
  
  static int ps8622_get_modes(struct drm_connector *connector)
  {
  	struct ps8622_bridge *ps8622;
  
  	ps8622 = connector_to_ps8622(connector);
  
  	return drm_panel_get_modes(ps8622->panel);
  }
  
  static const struct drm_connector_helper_funcs ps8622_connector_helper_funcs = {
  	.get_modes = ps8622_get_modes,
  };
  
  static const struct drm_connector_funcs ps8622_connector_funcs = {
  	.fill_modes = drm_helper_probe_single_connector_modes,
  	.destroy = drm_connector_cleanup,
  	.reset = drm_atomic_helper_connector_reset,
  	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
  	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
  };
  
  static int ps8622_attach(struct drm_bridge *bridge)
  {
  	struct ps8622_bridge *ps8622 = bridge_to_ps8622(bridge);
  	int ret;
  
  	if (!bridge->encoder) {
  		DRM_ERROR("Parent encoder object not found");
  		return -ENODEV;
  	}
  
  	ps8622->connector.polled = DRM_CONNECTOR_POLL_HPD;
  	ret = drm_connector_init(bridge->dev, &ps8622->connector,
  			&ps8622_connector_funcs, DRM_MODE_CONNECTOR_LVDS);
  	if (ret) {
  		DRM_ERROR("Failed to initialize connector with drm\n");
  		return ret;
  	}
  	drm_connector_helper_add(&ps8622->connector,
  					&ps8622_connector_helper_funcs);
  	drm_connector_register(&ps8622->connector);
  	drm_connector_attach_encoder(&ps8622->connector,
  							bridge->encoder);
  
  	if (ps8622->panel)
  		drm_panel_attach(ps8622->panel, &ps8622->connector);
  
  	drm_helper_hpd_irq_event(ps8622->connector.dev);
  
  	return ret;
  }
  
  static const struct drm_bridge_funcs ps8622_bridge_funcs = {
  	.pre_enable = ps8622_pre_enable,
  	.enable = ps8622_enable,
  	.disable = ps8622_disable,
  	.post_disable = ps8622_post_disable,
  	.attach = ps8622_attach,
  };
  
  static const struct of_device_id ps8622_devices[] = {
  	{.compatible = "parade,ps8622",},
  	{.compatible = "parade,ps8625",},
  	{}
  };
  MODULE_DEVICE_TABLE(of, ps8622_devices);
  
  static int ps8622_probe(struct i2c_client *client,
  					const struct i2c_device_id *id)
  {
  	struct device *dev = &client->dev;
  	struct ps8622_bridge *ps8622;
  	int ret;
  
  	ps8622 = devm_kzalloc(dev, sizeof(*ps8622), GFP_KERNEL);
  	if (!ps8622)
  		return -ENOMEM;
  
  	ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0, &ps8622->panel, NULL);
  	if (ret)
  		return ret;
  
  	ps8622->client = client;
  
  	ps8622->v12 = devm_regulator_get(dev, "vdd12");
  	if (IS_ERR(ps8622->v12)) {
  		dev_info(dev, "no 1.2v regulator found for PS8622\n");
  		ps8622->v12 = NULL;
  	}
  
  	ps8622->gpio_slp = devm_gpiod_get(dev, "sleep", GPIOD_OUT_HIGH);
  	if (IS_ERR(ps8622->gpio_slp)) {
  		ret = PTR_ERR(ps8622->gpio_slp);
  		dev_err(dev, "cannot get gpio_slp %d\n", ret);
  		return ret;
  	}
  
  	/*
  	 * Assert the reset pin high to avoid the bridge being
  	 * initialized prematurely
  	 */
  	ps8622->gpio_rst = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
  	if (IS_ERR(ps8622->gpio_rst)) {
  		ret = PTR_ERR(ps8622->gpio_rst);
  		dev_err(dev, "cannot get gpio_rst %d\n", ret);
  		return ret;
  	}
  
  	ps8622->max_lane_count = id->driver_data;
  
  	if (of_property_read_u32(dev->of_node, "lane-count",
  						&ps8622->lane_count)) {
  		ps8622->lane_count = ps8622->max_lane_count;
  	} else if (ps8622->lane_count > ps8622->max_lane_count) {
  		dev_info(dev, "lane-count property is too high,"
  						"using max_lane_count\n");
  		ps8622->lane_count = ps8622->max_lane_count;
  	}
  
  	if (!of_find_property(dev->of_node, "use-external-pwm", NULL)) {
  		ps8622->bl = backlight_device_register("ps8622-backlight",
  				dev, ps8622, &ps8622_backlight_ops,
  				NULL);
  		if (IS_ERR(ps8622->bl)) {
  			DRM_ERROR("failed to register backlight\n");
  			ret = PTR_ERR(ps8622->bl);
  			ps8622->bl = NULL;
  			return ret;
  		}
  		ps8622->bl->props.max_brightness = PS8622_MAX_BRIGHTNESS;
  		ps8622->bl->props.brightness = PS8622_MAX_BRIGHTNESS;
  	}
  
  	ps8622->bridge.funcs = &ps8622_bridge_funcs;
  	ps8622->bridge.of_node = dev->of_node;
  	drm_bridge_add(&ps8622->bridge);
  
  	i2c_set_clientdata(client, ps8622);
  
  	return 0;
  }
  
  static int ps8622_remove(struct i2c_client *client)
  {
  	struct ps8622_bridge *ps8622 = i2c_get_clientdata(client);
  
  	backlight_device_unregister(ps8622->bl);
  	drm_bridge_remove(&ps8622->bridge);
  
  	return 0;
  }
  
  static const struct i2c_device_id ps8622_i2c_table[] = {
  	/* Device type, max_lane_count */
  	{"ps8622", 1},
  	{"ps8625", 2},
  	{},
  };
  MODULE_DEVICE_TABLE(i2c, ps8622_i2c_table);
  
  static struct i2c_driver ps8622_driver = {
  	.id_table	= ps8622_i2c_table,
  	.probe		= ps8622_probe,
  	.remove		= ps8622_remove,
  	.driver		= {
  		.name	= "ps8622",
  		.of_match_table = ps8622_devices,
  	},
  };
  module_i2c_driver(ps8622_driver);
  
  MODULE_AUTHOR("Vincent Palatin <vpalatin@chromium.org>");
  MODULE_DESCRIPTION("Parade ps8622/ps8625 eDP-LVDS converter driver");
  MODULE_LICENSE("GPL v2");
  