The IT66121 is a DVO to HDMI converter, LS3A5000+LS7A1000 ML5A_MB use this
chip to support HDMI output. Thus add a drm bridge based driver for it.
This patch is developed with drivers/gpu/drm/bridge/ite-it66121.c as base.

Signed-off-by: Sui Jingfeng <suijingf...@loongson.cn>
---
 drivers/gpu/drm/loongson/Kconfig            |   1 +
 drivers/gpu/drm/loongson/Makefile           |   2 +
 drivers/gpu/drm/loongson/ite_it66121.c      | 749 ++++++++++++++++++++
 drivers/gpu/drm/loongson/ite_it66121.h      |  19 +
 drivers/gpu/drm/loongson/ite_it66121_regs.h | 268 +++++++
 5 files changed, 1039 insertions(+)
 create mode 100644 drivers/gpu/drm/loongson/ite_it66121.c
 create mode 100644 drivers/gpu/drm/loongson/ite_it66121.h
 create mode 100644 drivers/gpu/drm/loongson/ite_it66121_regs.h

diff --git a/drivers/gpu/drm/loongson/Kconfig b/drivers/gpu/drm/loongson/Kconfig
index df6946d505fa..a96f5699099e 100644
--- a/drivers/gpu/drm/loongson/Kconfig
+++ b/drivers/gpu/drm/loongson/Kconfig
@@ -7,6 +7,7 @@ config DRM_LOONGSON
        select DRM_TTM
        select I2C
        select I2C_ALGOBIT
+       select REGMAP_I2C
        help
          This is a DRM driver for Loongson Graphics, it may including
          LS7A2000, LS7A1000, LS2K2000 and LS2K1000 etc. Loongson LS7A
diff --git a/drivers/gpu/drm/loongson/Makefile 
b/drivers/gpu/drm/loongson/Makefile
index bef00b2c5569..1459d19b2c90 100644
--- a/drivers/gpu/drm/loongson/Makefile
+++ b/drivers/gpu/drm/loongson/Makefile
@@ -20,4 +20,6 @@ loongson-y += loongson_device.o \
              loongson_module.o \
              loongson_vbios.o
 
+loongson-y += ite_it66121.o
+
 obj-$(CONFIG_DRM_LOONGSON) += loongson.o
diff --git a/drivers/gpu/drm/loongson/ite_it66121.c 
b/drivers/gpu/drm/loongson/ite_it66121.c
new file mode 100644
index 000000000000..7b085575f864
--- /dev/null
+++ b/drivers/gpu/drm/loongson/ite_it66121.c
@@ -0,0 +1,749 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2020 BayLibre, SAS
+ * Author: Phong LE <p...@baylibre.com>
+ * Copyright (C) 2018-2019, Artem Mygaiev
+ * Copyright (C) 2017, Fresco Logic, Incorporated.
+ *
+ * IT66121 HDMI transmitter driver
+ */
+
+#include <linux/media-bus-format.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/bitfield.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_bridge.h>
+#include <drm/drm_edid.h>
+#include <drm/drm_modes.h>
+#include <drm/drm_print.h>
+#include <drm/drm_probe_helper.h>
+
+#include "ite_it66121.h"
+#include "ite_it66121_regs.h"
+
+#define IT66121_CHIP_NAME                       "IT66121"
+
+struct it66121_bridge {
+       struct drm_bridge bridge;
+       struct drm_connector connector;
+       struct regmap *regmap;
+       struct i2c_client *client;
+       /* Protects fields below and device registers */
+       struct mutex lock;
+       u16 vendor_id;
+       u16 device_id;
+       u32 revision;
+};
+
+static inline struct it66121_bridge *
+bridge_to_it66121(struct drm_bridge *bridge)
+{
+       return container_of(bridge, struct it66121_bridge, bridge);
+}
+
+static inline struct it66121_bridge *
+connector_to_it66121(struct drm_connector *connector)
+{
+       return container_of(connector, struct it66121_bridge, connector);
+}
+
+static const struct regmap_range_cfg it66121_regmap_banks[] = {
+       {
+               .name = IT66121_CHIP_NAME,
+               .range_min = 0x00,
+               .range_max = 0x1FF,
+               .selector_reg = IT66121_CLK_BANK_REG,
+               .selector_mask = 0x1,
+               .selector_shift = 0,
+               .window_start = 0x00,
+               .window_len = 0x100,
+       },
+};
+
+static const struct regmap_config it66121_regmap_config = {
+       .val_bits = 8,
+       .reg_bits = 8,
+       .max_register = 0x1FF,
+       .ranges = it66121_regmap_banks,
+       .num_ranges = ARRAY_SIZE(it66121_regmap_banks),
+};
+
+static inline int it66121_preamble_ddc(struct it66121_bridge *itb)
+{
+       return regmap_write(itb->regmap, IT66121_MASTER_SEL_REG,
+                           IT66121_MASTER_SEL_HOST);
+}
+
+static inline int it66121_fire_afe(struct it66121_bridge *itb)
+{
+       return regmap_write(itb->regmap, IT66121_AFE_DRV_REG, 0);
+}
+
+static int it66121_configure_input(struct it66121_bridge *itb)
+{
+       int ret;
+
+       ret = regmap_write(itb->regmap, IT66121_INPUT_MODE_REG,
+                          IT66121_INPUT_MODE_RGB888);
+       if (ret)
+               return ret;
+
+       return regmap_write(itb->regmap, IT66121_INPUT_CSC_REG,
+                           IT66121_INPUT_CSC_NO_CONV);
+}
+
+/*
+ * it66121_configure_afe() - Configure the analog front end
+ * @ctx: it66121_ctx object
+ * @mode: mode to configure
+ *
+ * RETURNS:
+ * zero if success, a negative error code otherwise.
+ */
+static int it66121_configure_afe(struct it66121_bridge *itb,
+                                const struct drm_display_mode *mode)
+{
+       int ret;
+
+       ret = regmap_write(itb->regmap, IT66121_AFE_DRV_REG,
+                          IT66121_AFE_DRV_RST);
+       if (ret)
+               return ret;
+
+       if (mode->clock > IT66121_AFE_CLK_HIGH) {
+               ret = regmap_write_bits(itb->regmap, IT66121_AFE_XP_REG,
+                                       IT66121_AFE_XP_GAINBIT |
+                                       IT66121_AFE_XP_ENO,
+                                       IT66121_AFE_XP_GAINBIT);
+               if (ret)
+                       return ret;
+
+               ret = regmap_write_bits(itb->regmap, IT66121_AFE_IP_REG,
+                                       IT66121_AFE_IP_GAINBIT |
+                                       IT66121_AFE_IP_ER0,
+                                       IT66121_AFE_IP_GAINBIT);
+               if (ret)
+                       return ret;
+
+               ret = regmap_write_bits(itb->regmap, IT66121_AFE_IP_REG,
+                                       IT66121_AFE_IP_EC1, 0);
+               if (ret)
+                       return ret;
+
+               ret = regmap_write_bits(itb->regmap, IT66121_AFE_XP_EC1_REG,
+                                       IT66121_AFE_XP_EC1_LOWCLK, 0x80);
+               if (ret)
+                       return ret;
+       } else {
+               ret = regmap_write_bits(itb->regmap, IT66121_AFE_XP_REG,
+                                       IT66121_AFE_XP_GAINBIT |
+                                       IT66121_AFE_XP_ENO,
+                                       IT66121_AFE_XP_ENO);
+               if (ret)
+                       return ret;
+
+               ret = regmap_write_bits(itb->regmap, IT66121_AFE_IP_REG,
+                                       IT66121_AFE_IP_GAINBIT |
+                                       IT66121_AFE_IP_ER0,
+                                       IT66121_AFE_IP_ER0);
+               if (ret)
+                       return ret;
+
+               ret = regmap_write_bits(itb->regmap, IT66121_AFE_IP_REG,
+                                       IT66121_AFE_IP_EC1,
+                                       IT66121_AFE_IP_EC1);
+               if (ret)
+                       return ret;
+
+               ret = regmap_write_bits(itb->regmap, IT66121_AFE_XP_EC1_REG,
+                                       IT66121_AFE_XP_EC1_LOWCLK,
+                                       IT66121_AFE_XP_EC1_LOWCLK);
+               if (ret)
+                       return ret;
+       }
+
+       /* Clear reset flags */
+       ret = regmap_write_bits(itb->regmap, IT66121_SW_RST_REG,
+                               IT66121_SW_RST_REF | IT66121_SW_RST_VID, 0);
+       if (ret)
+               return ret;
+
+       return it66121_fire_afe(itb);
+}
+
+static inline int it66121_wait_ddc_ready(struct it66121_bridge *itb)
+{
+       u32 error = IT66121_DDC_STATUS_NOACK |
+                   IT66121_DDC_STATUS_WAIT_BUS |
+                   IT66121_DDC_STATUS_ARBI_LOSE;
+       u32 done = IT66121_DDC_STATUS_TX_DONE;
+       int ret, val;
+
+       ret = regmap_read_poll_timeout(itb->regmap, IT66121_DDC_STATUS_REG,
+                                      val, val & (error | done),
+                                      IT66121_EDID_SLEEP_US,
+                                      IT66121_EDID_TIMEOUT_US);
+       if (ret)
+               return ret;
+
+       if (val & error)
+               return -EAGAIN;
+
+       return 0;
+}
+
+static int it66121_abort_ddc_ops(struct it66121_bridge *itb)
+{
+       unsigned int swreset, cpdesire;
+       int ret;
+
+       ret = regmap_read(itb->regmap, IT66121_SW_RST_REG, &swreset);
+       if (ret)
+               return ret;
+
+       ret = regmap_read(itb->regmap, IT66121_HDCP_REG, &cpdesire);
+       if (ret)
+               return ret;
+
+       ret = regmap_write(itb->regmap, IT66121_HDCP_REG,
+                          cpdesire & (~IT66121_HDCP_CPDESIRED & 0xFF));
+       if (ret)
+               return ret;
+
+       ret = regmap_write(itb->regmap, IT66121_SW_RST_REG,
+                          (swreset | IT66121_SW_RST_HDCP));
+       if (ret)
+               return ret;
+
+       ret = it66121_preamble_ddc(itb);
+       if (ret)
+               return ret;
+
+       ret = regmap_write(itb->regmap, IT66121_DDC_COMMAND_REG,
+                          IT66121_DDC_COMMAND_ABORT);
+       if (ret)
+               return ret;
+
+       return it66121_wait_ddc_ready(itb);
+}
+
+static int it66121_get_edid_block(void *context,
+                                 u8 *buf,
+                                 unsigned int block,
+                                 size_t len)
+{
+       struct it66121_bridge *itb = (struct it66121_bridge *)context;
+       int remain = len;
+       int offset = 0;
+       int ret, cnt;
+
+       offset = (block % 2) * len;
+       block = block / 2;
+
+       while (remain > 0) {
+               cnt = (remain > IT66121_EDID_FIFO_SIZE) ?
+                               IT66121_EDID_FIFO_SIZE : remain;
+
+               ret = regmap_write(itb->regmap, IT66121_DDC_COMMAND_REG,
+                                  IT66121_DDC_COMMAND_FIFO_CLR);
+               if (ret)
+                       return ret;
+
+               ret = it66121_wait_ddc_ready(itb);
+               if (ret)
+                       return ret;
+
+               ret = regmap_write(itb->regmap, IT66121_DDC_OFFSET_REG, offset);
+               if (ret)
+                       return ret;
+
+               ret = regmap_write(itb->regmap, IT66121_DDC_BYTE_REG, cnt);
+               if (ret)
+                       return ret;
+
+               ret = regmap_write(itb->regmap, IT66121_DDC_SEGMENT_REG, block);
+               if (ret)
+                       return ret;
+
+               ret = regmap_write(itb->regmap, IT66121_DDC_COMMAND_REG,
+                                  IT66121_DDC_COMMAND_EDID_READ);
+               if (ret)
+                       return ret;
+
+               offset += cnt;
+               remain -= cnt;
+
+               ret = it66121_wait_ddc_ready(itb);
+               if (ret) {
+                       it66121_abort_ddc_ops(itb);
+                       return ret;
+               }
+
+               ret = regmap_noinc_read(itb->regmap, IT66121_DDC_RD_FIFO_REG,
+                                       buf, cnt);
+               if (ret)
+                       return ret;
+
+               buf += cnt;
+       }
+
+       return 0;
+}
+
+static bool it66121_is_hpd_detect(struct it66121_bridge *itb)
+{
+       int val;
+
+       if (regmap_read(itb->regmap, IT66121_SYS_STATUS_REG, &val))
+               return false;
+
+       return val & IT66121_SYS_STATUS_HPDETECT;
+}
+
+static int it66121_connector_get_modes(struct drm_connector *connector)
+{
+       struct it66121_bridge *itb = connector_to_it66121(connector);
+       u32 bus_format = MEDIA_BUS_FMT_RGB888_1X24;
+       int num_modes = 0;
+       struct edid *edid;
+       int ret;
+
+       edid = drm_bridge_get_edid(&itb->bridge, connector);
+       if (!edid) {
+               drm_err(connector->dev, "Failed to read EDID\n");
+               goto failed;
+       }
+
+       if (drm_connector_update_edid_property(connector, edid)) {
+               drm_err(connector->dev, "Failed to update EDID\n");
+               goto failed;
+       }
+
+       ret = drm_display_info_set_bus_formats(&connector->display_info,
+                                              &bus_format, 1);
+       if (ret)
+               goto failed;
+
+       num_modes = drm_add_edid_modes(connector, edid);
+
+failed:
+       return num_modes;
+}
+
+static int it66121_connector_detect_ctx(struct drm_connector *connector,
+                                       struct drm_modeset_acquire_ctx *ctx,
+                                       bool force)
+{
+       struct it66121_bridge *itb = connector_to_it66121(connector);
+
+       return it66121_is_hpd_detect(itb) ? connector_status_connected
+                                         : connector_status_disconnected;
+}
+
+static struct drm_connector_helper_funcs it66121_connector_helper_funcs = {
+       .get_modes = it66121_connector_get_modes,
+       .detect_ctx = it66121_connector_detect_ctx,
+};
+
+static const struct drm_connector_funcs it66121_connector_funcs = {
+       .reset = drm_atomic_helper_connector_reset,
+       .fill_modes = drm_helper_probe_single_connector_modes,
+       .destroy = drm_connector_cleanup,
+       .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
+       .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+};
+
+static int it66121_bridge_connector_init(struct drm_bridge *bridge)
+{
+       struct it66121_bridge *itb = bridge_to_it66121(bridge);
+       struct drm_connector *connector = &itb->connector;
+       int ret;
+
+       if (bridge->ops & DRM_BRIDGE_OP_HPD) {
+               connector->polled = DRM_CONNECTOR_POLL_HPD;
+       } else {
+               connector->polled = DRM_CONNECTOR_POLL_CONNECT |
+                                   DRM_CONNECTOR_POLL_DISCONNECT;
+       }
+
+       ret = drm_connector_init(bridge->dev,
+                                connector,
+                                &it66121_connector_funcs,
+                                bridge->type);
+       if (ret)
+               return ret;
+
+       drm_connector_helper_add(connector, &it66121_connector_helper_funcs);
+
+       drm_connector_attach_encoder(connector, bridge->encoder);
+
+       return 0;
+}
+
+static int it66121_bridge_attach(struct drm_bridge *bridge,
+                                enum drm_bridge_attach_flags flags)
+{
+       struct it66121_bridge *itb = bridge_to_it66121(bridge);
+       int ret;
+
+       ret = it66121_bridge_connector_init(bridge);
+       if (ret)
+               return ret;
+
+       ret = regmap_write_bits(itb->regmap, IT66121_CLK_BANK_REG,
+                               IT66121_CLK_BANK_PWROFF_RCLK, 0);
+       if (ret)
+               return ret;
+
+       ret = regmap_write_bits(itb->regmap, IT66121_INT_REG,
+                               IT66121_INT_TX_CLK_OFF, 0);
+       if (ret)
+               return ret;
+
+       ret = regmap_write_bits(itb->regmap, IT66121_AFE_DRV_REG,
+                               IT66121_AFE_DRV_PWD, 0);
+       if (ret)
+               return ret;
+
+       ret = regmap_write_bits(itb->regmap, IT66121_AFE_XP_REG,
+                               IT66121_AFE_XP_PWDI | IT66121_AFE_XP_PWDPLL, 0);
+       if (ret)
+               return ret;
+
+       ret = regmap_write_bits(itb->regmap, IT66121_AFE_IP_REG,
+                               IT66121_AFE_IP_PWDPLL, 0);
+       if (ret)
+               return ret;
+
+       ret = regmap_write_bits(itb->regmap, IT66121_AFE_DRV_REG,
+                               IT66121_AFE_DRV_RST, 0);
+       if (ret)
+               return ret;
+
+       ret = regmap_write_bits(itb->regmap, IT66121_AFE_XP_REG,
+                               IT66121_AFE_XP_RESETB, IT66121_AFE_XP_RESETB);
+       if (ret)
+               return ret;
+
+       ret = regmap_write_bits(itb->regmap, IT66121_AFE_IP_REG,
+                               IT66121_AFE_IP_RESETB, IT66121_AFE_IP_RESETB);
+       if (ret)
+               return ret;
+
+       ret = regmap_write_bits(itb->regmap, IT66121_SW_RST_REG,
+                               IT66121_SW_RST_REF,
+                               IT66121_SW_RST_REF);
+       if (ret)
+               return ret;
+
+       drm_info(bridge->dev,
+                "IT66121 attached, Vendor ID: 0x%x, Device ID: 0x%x\n",
+                itb->vendor_id, itb->device_id);
+
+       /* Per programming manual, sleep here for bridge to settle */
+       msleep(50);
+
+       return 0;
+}
+
+static void it66121_bridge_enable(struct drm_bridge *bridge,
+                                 struct drm_bridge_state *state)
+{
+       struct it66121_bridge *itb = bridge_to_it66121(bridge);
+       struct regmap *regmap = itb->regmap;
+       int ret;
+
+       ret = regmap_clear_bits(regmap, IT66121_AVMUTE_REG, IT66121_AVMUTE_BIT);
+       if (ret)
+               drm_err(bridge->dev, "Enable it66121 bridge failed");
+
+       regmap_write(regmap, IT66121_PKT_GEN_CTRL_REG,
+                    IT66121_PKT_GEN_CTRL_ON | IT66121_PKT_GEN_CTRL_RPT);
+}
+
+static void it66121_bridge_disable(struct drm_bridge *bridge,
+                                  struct drm_bridge_state *bridge_state)
+{
+       struct it66121_bridge *itb = bridge_to_it66121(bridge);
+       struct regmap *regmap = itb->regmap;
+       int ret;
+
+       ret = regmap_set_bits(regmap, IT66121_AVMUTE_REG, IT66121_AVMUTE_BIT);
+       if (ret)
+               drm_err(bridge->dev, "Disable it66121 bridge failed");
+
+       regmap_write(regmap, IT66121_PKT_GEN_CTRL_REG,
+                    IT66121_PKT_GEN_CTRL_ON | IT66121_PKT_GEN_CTRL_RPT);
+}
+
+static void it66121_bridge_mode_set(struct drm_bridge *bridge,
+                                   const struct drm_display_mode *mode,
+                                   const struct drm_display_mode *adj_mode)
+{
+       struct it66121_bridge *itb = bridge_to_it66121(bridge);
+       struct hdmi_avi_infoframe avi_infoframe;
+       u8 av_buf[HDMI_INFOFRAME_SIZE(AVI)];
+       int ret;
+
+       mutex_lock(&itb->lock);
+
+       hdmi_avi_infoframe_init(&avi_infoframe);
+
+       ret = drm_hdmi_avi_infoframe_from_display_mode(&avi_infoframe,
+                                                      &itb->connector,
+                                                      adj_mode);
+       if (ret) {
+               drm_err(bridge->dev, "Failed to setup AVI infoframe\n");
+               goto unlock;
+       }
+
+       ret = hdmi_avi_infoframe_pack(&avi_infoframe, av_buf, sizeof(av_buf));
+       if (ret < 0) {
+               drm_err(bridge->dev, "Failed to pack infoframe\n");
+               goto unlock;
+       }
+
+       /* Write new AVI infoframe packet */
+       ret = regmap_bulk_write(itb->regmap, IT66121_AVIINFO_DB1_REG,
+                               &av_buf[HDMI_INFOFRAME_HEADER_SIZE],
+                               HDMI_AVI_INFOFRAME_SIZE);
+       if (ret)
+               goto unlock;
+
+       if (regmap_write(itb->regmap, IT66121_AVIINFO_CSUM_REG, av_buf[3]))
+               goto unlock;
+
+       /* Enable AVI infoframe */
+       if (regmap_write(itb->regmap, IT66121_AVI_INFO_PKT_REG,
+                        IT66121_AVI_INFO_PKT_ON | IT66121_AVI_INFO_PKT_RPT))
+               goto unlock;
+
+       /* Set TX mode to HDMI */
+       if (regmap_write(itb->regmap, IT66121_HDMI_MODE_REG, 
IT66121_HDMI_MODE_HDMI))
+               goto unlock;
+
+       if (regmap_write_bits(itb->regmap, IT66121_CLK_BANK_REG,
+                             IT66121_CLK_BANK_PWROFF_TXCLK,
+                             IT66121_CLK_BANK_PWROFF_TXCLK))
+               goto unlock;
+
+       if (it66121_configure_input(itb))
+               goto unlock;
+
+       if (it66121_configure_afe(itb, adj_mode))
+               goto unlock;
+
+       if (regmap_write_bits(itb->regmap, IT66121_CLK_BANK_REG,
+                             IT66121_CLK_BANK_PWROFF_TXCLK, 0))
+               goto unlock;
+
+unlock:
+       mutex_unlock(&itb->lock);
+}
+
+static enum drm_mode_status
+it66121_bridge_mode_valid(struct drm_bridge *bridge,
+                         const struct drm_display_info *info,
+                         const struct drm_display_mode *mode)
+{
+       if (mode->clock > 148500)
+               return MODE_CLOCK_HIGH;
+
+       if (mode->clock < 25000)
+               return MODE_CLOCK_LOW;
+
+       return MODE_OK;
+}
+
+static struct edid *it66121_bridge_get_edid(struct drm_bridge *bridge,
+                                           struct drm_connector *connector)
+{
+       struct it66121_bridge *itb = bridge_to_it66121(bridge);
+       struct edid *edid;
+       int ret;
+
+       mutex_lock(&itb->lock);
+       ret = it66121_preamble_ddc(itb);
+       if (ret) {
+               edid = NULL;
+               goto unlock;
+       }
+
+       ret = regmap_write(itb->regmap, IT66121_DDC_HEADER_REG,
+                          IT66121_DDC_HEADER_EDID);
+       if (ret) {
+               edid = NULL;
+               goto unlock;
+       }
+
+       edid = drm_do_get_edid(connector, it66121_get_edid_block, itb);
+
+unlock:
+       mutex_unlock(&itb->lock);
+
+       return edid;
+}
+
+static void it66121_bridge_detach(struct drm_bridge *bridge)
+{
+       struct it66121_bridge *itb = bridge_to_it66121(bridge);
+
+       mutex_destroy(&itb->lock);
+
+       i2c_unregister_device(itb->client);
+
+       drm_bridge_remove(bridge);
+}
+
+static const struct drm_bridge_funcs it66121_bridge_funcs = {
+       .atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
+       .atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
+       .atomic_reset = drm_atomic_helper_bridge_reset,
+       .attach = it66121_bridge_attach,
+       .detach = it66121_bridge_detach,
+       .atomic_enable = it66121_bridge_enable,
+       .atomic_disable = it66121_bridge_disable,
+       .mode_set = it66121_bridge_mode_set,
+       .mode_valid = it66121_bridge_mode_valid,
+       .get_edid = it66121_bridge_get_edid,
+};
+
+static void it66121_bridge_get_version(struct it66121_bridge *itb)
+{
+       u32 vendor_ids[2] = { 0 };
+       u32 device_ids[2] = { 0 };
+
+       regmap_read(itb->regmap, IT66121_VENDOR_ID0_REG, &vendor_ids[0]);
+       regmap_read(itb->regmap, IT66121_VENDOR_ID1_REG, &vendor_ids[1]);
+       regmap_read(itb->regmap, IT66121_DEVICE_ID0_REG, &device_ids[0]);
+       regmap_read(itb->regmap, IT66121_DEVICE_ID1_REG, &device_ids[1]);
+
+       /* Revision is shared with DEVICE_ID1 */
+       itb->revision = FIELD_GET(IT66121_REVISION_MASK, device_ids[1]);
+       device_ids[1] &= IT66121_DEVICE_ID1_MASK;
+
+       itb->vendor_id = vendor_ids[1] << 8 | vendor_ids[0];
+       itb->device_id = device_ids[1] << 8 | device_ids[0];
+}
+
+static void it66121_bridge_init_base(struct it66121_bridge *itb, bool hpd)
+{
+       struct drm_bridge *bridge = &itb->bridge;
+
+       bridge->funcs = &it66121_bridge_funcs;
+       bridge->type = DRM_MODE_CONNECTOR_HDMIA;
+       bridge->ops = DRM_BRIDGE_OP_EDID;
+
+       if (hpd)
+               bridge->ops |= DRM_BRIDGE_OP_HPD;
+
+       drm_bridge_add(bridge);
+}
+
+/*
+ * The device address is 0x98 if PCADR pin is pulled low, 0x98 >> 1 = 0x4c
+ * The device address is 0x9A if PCADR pin is pulled high, 0x9A >> 1 = 0x4d
+ */
+static bool it66121_probe_slave(struct drm_device *ddev,
+                               struct i2c_adapter *adapter,
+                               u8 *addr)
+{
+       struct i2c_msg msg = {
+               .len = 0,
+       };
+       int num = 3;
+       int count;
+       int i;
+
+       /* Try slave address 0x4c */
+       msg.addr = 0x4c;
+       count = 0;
+       for (i = 0; i < num; i++) {
+               count += i2c_transfer(adapter, &msg, 1);
+               udelay(9);
+       }
+
+       if (count == num) {
+               *addr = 0x4c;
+               return true;
+       }
+
+       /* Try slave address 0x4d */
+       msg.addr = 0x4d;
+       count = 0;
+       for (i = 0; i < num; i++) {
+               count += i2c_transfer(adapter, &msg, 1);
+               udelay(9);
+       }
+
+       if (count == num) {
+               *addr = 0x4d;
+               return true;
+       }
+
+       drm_err(ddev, "No reliable slave i2c device found\n");
+
+       /*
+        * If no reliable slave i2c device found, we would like drop the
+        * support.
+        */
+       return false;
+}
+
+struct drm_bridge *it66121_bridge_create(struct drm_device *ddev,
+                                        struct i2c_adapter *i2c,
+                                        u8 addr,
+                                        bool enable_hpd,
+                                        u32 int_gpio,
+                                        unsigned int pipe)
+{
+       struct i2c_board_info it66121_board_info = {
+               .type = IT66121_CHIP_NAME,
+       };
+       struct it66121_bridge *itb;
+       struct i2c_client *client;
+       u8 addr_probed;
+
+       if (!it66121_probe_slave(ddev, i2c, &addr_probed))
+               return NULL;
+
+       if (addr != addr_probed) {
+               drm_warn(ddev, "device address(0x%x) is not correct\n", addr);
+               addr = addr_probed;
+       }
+
+       it66121_board_info.addr = addr;
+
+       itb = devm_kzalloc(ddev->dev, sizeof(*itb), GFP_KERNEL);
+       if (!itb)
+               return NULL;
+
+       client = i2c_new_client_device(i2c, &it66121_board_info);
+       if (IS_ERR(client))
+               return NULL;
+
+       drm_info(ddev, "i2c client %s@0x%02x created\n",
+                it66121_board_info.type, it66121_board_info.addr);
+
+       itb->client = client;
+
+       i2c_set_clientdata(client, itb);
+
+       mutex_init(&itb->lock);
+
+       itb->regmap = devm_regmap_init_i2c(client, &it66121_regmap_config);
+       if (IS_ERR(itb->regmap)) {
+               drm_err(ddev, "Failed to map registers\n");
+               return NULL;
+       }
+
+       it66121_bridge_get_version(itb);
+
+       it66121_bridge_init_base(itb, enable_hpd);
+
+       return &itb->bridge;
+}
diff --git a/drivers/gpu/drm/loongson/ite_it66121.h 
b/drivers/gpu/drm/loongson/ite_it66121.h
new file mode 100644
index 000000000000..c3e26cce1b02
--- /dev/null
+++ b/drivers/gpu/drm/loongson/ite_it66121.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) 2023 Loongson Technology Corporation Limited
+ */
+
+#ifndef __ITE_IT66121_H__
+#define __ITE_IT66121_H__
+
+#include <drm/drm_bridge.h>
+#include <drm/drm_device.h>
+
+struct drm_bridge *it66121_bridge_create(struct drm_device *ddev,
+                                        struct i2c_adapter *i2c,
+                                        u8 addr,
+                                        bool enable_hpd,
+                                        u32 int_gpio,
+                                        unsigned int pipe);
+
+#endif
diff --git a/drivers/gpu/drm/loongson/ite_it66121_regs.h 
b/drivers/gpu/drm/loongson/ite_it66121_regs.h
new file mode 100644
index 000000000000..57118a4501c1
--- /dev/null
+++ b/drivers/gpu/drm/loongson/ite_it66121_regs.h
@@ -0,0 +1,268 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+/*
+ * Copyright (C) 2020 BayLibre, SAS
+ * Author: Phong LE <p...@baylibre.com>
+ * Copyright (C) 2018-2019, Artem Mygaiev
+ * Copyright (C) 2017, Fresco Logic, Incorporated.
+ */
+
+#ifndef __ITE_IT66121_h__
+#define __ITE_IT66121_h__
+
+#define IT66121_VENDOR_ID0_REG                 0x00
+#define IT66121_VENDOR_ID1_REG                 0x01
+#define IT66121_DEVICE_ID0_REG                 0x02
+#define IT66121_DEVICE_ID1_REG                 0x03
+
+#define IT66121_REVISION_MASK                  GENMASK(7, 4)
+#define IT66121_DEVICE_ID1_MASK                        GENMASK(3, 0)
+
+#define IT66121_MASTER_SEL_REG                 0x10
+#define IT66121_MASTER_SEL_HOST                        BIT(0)
+
+#define IT66121_AFE_DRV_REG                    0x61
+#define IT66121_AFE_DRV_RST                    BIT(4)
+#define IT66121_AFE_DRV_PWD                    BIT(5)
+
+#define IT66121_INPUT_MODE_REG                 0x70
+#define IT66121_INPUT_MODE_RGB888              (0 << 6)
+#define IT66121_INPUT_MODE_YUV422              BIT(6)
+#define IT66121_INPUT_MODE_YUV444              (2 << 6)
+#define IT66121_INPUT_MODE_CCIR656             BIT(4)
+#define IT66121_INPUT_MODE_SYNCEMB             BIT(3)
+#define IT66121_INPUT_MODE_DDR                 BIT(2)
+
+#define IT66121_INPUT_CSC_REG                  0x72
+#define IT66121_INPUT_CSC_ENDITHER             BIT(7)
+#define IT66121_INPUT_CSC_ENUDFILTER           BIT(6)
+#define IT66121_INPUT_CSC_DNFREE_GO            BIT(5)
+#define IT66121_INPUT_CSC_RGB_TO_YUV           0x02
+#define IT66121_INPUT_CSC_YUV_TO_RGB           0x03
+#define IT66121_INPUT_CSC_NO_CONV              0x00
+
+#define IT66121_AFE_XP_REG                     0x62
+#define IT66121_AFE_XP_GAINBIT                 BIT(7)
+#define IT66121_AFE_XP_PWDPLL                  BIT(6)
+#define IT66121_AFE_XP_ENI                     BIT(5)
+#define IT66121_AFE_XP_ENO                     BIT(4)
+#define IT66121_AFE_XP_RESETB                  BIT(3)
+#define IT66121_AFE_XP_PWDI                    BIT(2)
+#define IT6610_AFE_XP_BYPASS                   BIT(0)
+
+#define IT66121_AFE_IP_REG                     0x64
+#define IT66121_AFE_IP_GAINBIT                 BIT(7)
+#define IT66121_AFE_IP_PWDPLL                  BIT(6)
+#define IT66121_AFE_IP_CKSEL_05                        (0 << 4)
+#define IT66121_AFE_IP_CKSEL_1                 BIT(4)
+#define IT66121_AFE_IP_CKSEL_2                 (2 << 4)
+#define IT66121_AFE_IP_CKSEL_2OR4              (3 << 4)
+#define IT66121_AFE_IP_ER0                     BIT(3)
+#define IT66121_AFE_IP_RESETB                  BIT(2)
+#define IT66121_AFE_IP_ENC                     BIT(1)
+#define IT66121_AFE_IP_EC1                     BIT(0)
+
+#define IT66121_AFE_XP_EC1_REG                 0x68
+#define IT66121_AFE_XP_EC1_LOWCLK              BIT(4)
+
+#define IT66121_SW_RST_REG                     0x04
+#define IT66121_SW_RST_REF                     BIT(5)
+#define IT66121_SW_RST_AREF                    BIT(4)
+#define IT66121_SW_RST_VID                     BIT(3)
+#define IT66121_SW_RST_AUD                     BIT(2)
+#define IT66121_SW_RST_HDCP                    BIT(0)
+
+#define IT66121_DDC_COMMAND_REG                        0x15
+#define IT66121_DDC_COMMAND_BURST_READ         0x0
+#define IT66121_DDC_COMMAND_EDID_READ          0x3
+#define IT66121_DDC_COMMAND_FIFO_CLR           0x9
+#define IT66121_DDC_COMMAND_SCL_PULSE          0xA
+#define IT66121_DDC_COMMAND_ABORT              0xF
+
+#define IT66121_HDCP_REG                       0x20
+#define IT66121_HDCP_CPDESIRED                 BIT(0)
+#define IT66121_HDCP_EN1P1FEAT                 BIT(1)
+
+#define IT66121_INT_STATUS1_REG                        0x06
+#define IT66121_INT_STATUS1_AUD_OVF            BIT(7)
+#define IT66121_INT_STATUS1_DDC_NOACK          BIT(5)
+#define IT66121_INT_STATUS1_DDC_FIFOERR                BIT(4)
+#define IT66121_INT_STATUS1_DDC_BUSHANG                BIT(2)
+#define IT66121_INT_STATUS1_RX_SENS_STATUS     BIT(1)
+#define IT66121_INT_STATUS1_HPD_STATUS         BIT(0)
+
+#define IT66121_DDC_HEADER_REG                 0x11
+#define IT66121_DDC_HEADER_HDCP                        0x74
+#define IT66121_DDC_HEADER_EDID                        0xA0
+
+#define IT66121_DDC_OFFSET_REG                 0x12
+#define IT66121_DDC_BYTE_REG                   0x13
+#define IT66121_DDC_SEGMENT_REG                        0x14
+#define IT66121_DDC_RD_FIFO_REG                        0x17
+
+#define IT66121_CLK_BANK_REG                   0x0F
+#define IT66121_CLK_BANK_PWROFF_RCLK           BIT(6)
+#define IT66121_CLK_BANK_PWROFF_ACLK           BIT(5)
+#define IT66121_CLK_BANK_PWROFF_TXCLK          BIT(4)
+#define IT66121_CLK_BANK_PWROFF_CRCLK          BIT(3)
+#define IT66121_CLK_BANK_0                     0
+#define IT66121_CLK_BANK_1                     1
+
+#define IT66121_INT_REG                                0x05
+#define IT66121_INT_ACTIVE_HIGH                        BIT(7)
+#define IT66121_INT_OPEN_DRAIN                 BIT(6)
+#define IT66121_INT_TX_CLK_OFF                 BIT(0)
+
+#define IT66121_INT_MASK1_REG                  0x09
+#define IT66121_INT_MASK1_AUD_OVF              BIT(7)
+#define IT66121_INT_MASK1_DDC_NOACK            BIT(5)
+#define IT66121_INT_MASK1_DDC_FIFOERR          BIT(4)
+#define IT66121_INT_MASK1_DDC_BUSHANG          BIT(2)
+#define IT66121_INT_MASK1_RX_SENS              BIT(1)
+#define IT66121_INT_MASK1_HPD                  BIT(0)
+
+#define IT66121_INT_CLR1_REG                   0x0C
+#define IT66121_INT_CLR1_PKTACP                        BIT(7)
+#define IT66121_INT_CLR1_PKTNULL               BIT(6)
+#define IT66121_INT_CLR1_PKTGEN                        BIT(5)
+#define IT66121_INT_CLR1_KSVLISTCHK            BIT(4)
+#define IT66121_INT_CLR1_AUTHDONE              BIT(3)
+#define IT66121_INT_CLR1_AUTHFAIL              BIT(2)
+#define IT66121_INT_CLR1_RX_SENS               BIT(1)
+#define IT66121_INT_CLR1_HPD                   BIT(0)
+
+#define IT66121_AVMUTE_REG                     0xC1
+#define IT66121_AVMUTE_BIT                     BIT(0)
+#define IT66121_AVMUTE_BLUESCR                 BIT(1)
+
+#define IT66121_PKT_CTS_CTRL_REG               0xC5
+#define IT66121_PKT_CTS_CTRL_SEL               BIT(1)
+
+#define IT66121_PKT_GEN_CTRL_REG               0xC6
+#define IT66121_PKT_GEN_CTRL_ON                        BIT(0)
+#define IT66121_PKT_GEN_CTRL_RPT               BIT(1)
+
+#define IT66121_AVIINFO_DB1_REG                        0x158
+#define IT66121_AVIINFO_DB2_REG                        0x159
+#define IT66121_AVIINFO_DB3_REG                        0x15A
+#define IT66121_AVIINFO_DB4_REG                        0x15B
+#define IT66121_AVIINFO_DB5_REG                        0x15C
+#define IT66121_AVIINFO_CSUM_REG               0x15D
+#define IT66121_AVIINFO_DB6_REG                        0x15E
+#define IT66121_AVIINFO_DB7_REG                        0x15F
+#define IT66121_AVIINFO_DB8_REG                        0x160
+#define IT66121_AVIINFO_DB9_REG                        0x161
+#define IT66121_AVIINFO_DB10_REG               0x162
+#define IT66121_AVIINFO_DB11_REG               0x163
+#define IT66121_AVIINFO_DB12_REG               0x164
+#define IT66121_AVIINFO_DB13_REG               0x165
+
+#define IT66121_AVI_INFO_PKT_REG               0xCD
+#define IT66121_AVI_INFO_PKT_ON                        BIT(0)
+#define IT66121_AVI_INFO_PKT_RPT               BIT(1)
+
+#define IT66121_HDMI_MODE_REG                  0xC0
+#define IT66121_HDMI_MODE_HDMI                 BIT(0)
+
+#define IT66121_SYS_STATUS_REG                 0x0E
+#define IT66121_SYS_STATUS_ACTIVE_IRQ          BIT(7)
+#define IT66121_SYS_STATUS_HPDETECT            BIT(6)
+#define IT66121_SYS_STATUS_SENDECTECT          BIT(5)
+#define IT66121_SYS_STATUS_VID_STABLE          BIT(4)
+#define IT66121_SYS_STATUS_AUD_CTS_CLR         BIT(1)
+#define IT66121_SYS_STATUS_CLEAR_IRQ           BIT(0)
+
+#define IT66121_DDC_STATUS_REG                 0x16
+#define IT66121_DDC_STATUS_TX_DONE             BIT(7)
+#define IT66121_DDC_STATUS_ACTIVE              BIT(6)
+#define IT66121_DDC_STATUS_NOACK               BIT(5)
+#define IT66121_DDC_STATUS_WAIT_BUS            BIT(4)
+#define IT66121_DDC_STATUS_ARBI_LOSE           BIT(3)
+#define IT66121_DDC_STATUS_FIFO_FULL           BIT(2)
+#define IT66121_DDC_STATUS_FIFO_EMPTY          BIT(1)
+#define IT66121_DDC_STATUS_FIFO_VALID          BIT(0)
+
+#define IT66121_EDID_SLEEP_US                  20000
+#define IT66121_EDID_TIMEOUT_US                        200000
+#define IT66121_EDID_FIFO_SIZE                 32
+
+#define IT66121_CLK_CTRL0_REG                  0x58
+#define IT66121_CLK_CTRL0_AUTO_OVER_SAMPLING   BIT(4)
+#define IT66121_CLK_CTRL0_EXT_MCLK_MASK                GENMASK(3, 2)
+#define IT66121_CLK_CTRL0_EXT_MCLK_128FS       (0 << 2)
+#define IT66121_CLK_CTRL0_EXT_MCLK_256FS       BIT(2)
+#define IT66121_CLK_CTRL0_EXT_MCLK_512FS       (2 << 2)
+#define IT66121_CLK_CTRL0_EXT_MCLK_1024FS      (3 << 2)
+#define IT66121_CLK_CTRL0_AUTO_IPCLK           BIT(0)
+#define IT66121_CLK_STATUS1_REG                        0x5E
+#define IT66121_CLK_STATUS2_REG                        0x5F
+
+#define IT66121_AUD_CTRL0_REG                  0xE0
+#define IT66121_AUD_SWL                                (3 << 6)
+#define IT66121_AUD_16BIT                      (0 << 6)
+#define IT66121_AUD_18BIT                      BIT(6)
+#define IT66121_AUD_20BIT                      (2 << 6)
+#define IT66121_AUD_24BIT                      (3 << 6)
+#define IT66121_AUD_SPDIFTC                    BIT(5)
+#define IT66121_AUD_SPDIF                      BIT(4)
+#define IT66121_AUD_I2S                                (0 << 4)
+#define IT66121_AUD_EN_I2S3                    BIT(3)
+#define IT66121_AUD_EN_I2S2                    BIT(2)
+#define IT66121_AUD_EN_I2S1                    BIT(1)
+#define IT66121_AUD_EN_I2S0                    BIT(0)
+#define IT66121_AUD_CTRL0_AUD_SEL              BIT(4)
+
+#define IT66121_AUD_CTRL1_REG                  0xE1
+#define IT66121_AUD_FIFOMAP_REG                        0xE2
+#define IT66121_AUD_CTRL3_REG                  0xE3
+#define IT66121_AUD_SRCVALID_FLAT_REG          0xE4
+#define IT66121_AUD_FLAT_SRC0                  BIT(4)
+#define IT66121_AUD_FLAT_SRC1                  BIT(5)
+#define IT66121_AUD_FLAT_SRC2                  BIT(6)
+#define IT66121_AUD_FLAT_SRC3                  BIT(7)
+#define IT66121_AUD_HDAUDIO_REG                        0xE5
+
+#define IT66121_AUD_PKT_CTS0_REG               0x130
+#define IT66121_AUD_PKT_CTS1_REG               0x131
+#define IT66121_AUD_PKT_CTS2_REG               0x132
+#define IT66121_AUD_PKT_N0_REG                 0x133
+#define IT66121_AUD_PKT_N1_REG                 0x134
+#define IT66121_AUD_PKT_N2_REG                 0x135
+
+#define IT66121_AUD_CHST_MODE_REG              0x191
+#define IT66121_AUD_CHST_CAT_REG               0x192
+#define IT66121_AUD_CHST_SRCNUM_REG            0x193
+#define IT66121_AUD_CHST_CHTNUM_REG            0x194
+#define IT66121_AUD_CHST_CA_FS_REG             0x198
+#define IT66121_AUD_CHST_OFS_WL_REG            0x199
+
+#define IT66121_AUD_PKT_CTS_CNT0_REG           0x1A0
+#define IT66121_AUD_PKT_CTS_CNT1_REG           0x1A1
+#define IT66121_AUD_PKT_CTS_CNT2_REG           0x1A2
+
+#define IT66121_AUD_FS_22P05K                  0x4
+#define IT66121_AUD_FS_44P1K                   0x0
+#define IT66121_AUD_FS_88P2K                   0x8
+#define IT66121_AUD_FS_176P4K                  0xC
+#define IT66121_AUD_FS_24K                     0x6
+#define IT66121_AUD_FS_48K                     0x2
+#define IT66121_AUD_FS_96K                     0xA
+#define IT66121_AUD_FS_192K                    0xE
+#define IT66121_AUD_FS_768K                    0x9
+#define IT66121_AUD_FS_32K                     0x3
+#define IT66121_AUD_FS_OTHER                   0x1
+
+#define IT66121_AUD_SWL_21BIT                  0xD
+#define IT66121_AUD_SWL_24BIT                  0xB
+#define IT66121_AUD_SWL_23BIT                  0x9
+#define IT66121_AUD_SWL_22BIT                  0x5
+#define IT66121_AUD_SWL_20BIT                  0x3
+#define IT66121_AUD_SWL_17BIT                  0xC
+#define IT66121_AUD_SWL_19BIT                  0x8
+#define IT66121_AUD_SWL_18BIT                  0x4
+#define IT66121_AUD_SWL_16BIT                  0x2
+#define IT66121_AUD_SWL_NOT_INDICATED          0x0
+
+#define IT66121_AFE_CLK_HIGH                   80000 /* Khz */
+
+#endif
-- 
2.34.1

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