From: lichenyang <licheny...@loongson.cn>

Implement use GPIO and I2C driver to detect connector
and fetch EDID via DDC.

v5:
- Use braidge->ddc to get EDID and detect connector.

v4:
- Delete the gpio_chip subsystem call.
- Delete some redundant prints.

v3:
- Change some driver log to the drm_ version.

v2:
- Optimize the error handling process.
- Delete loongson_i2c_bus_match and loongson_i2c_add function.
- Optimize part of the code flow.

Signed-off-by: liyi <l...@loongson.cn>
Signed-off-by: lichenyang <licheny...@loongson.cn>
Signed-off-by: Chenyang Li <licheny...@loongson.cn>
---
 drivers/gpu/drm/loongson/Makefile           |   1 +
 drivers/gpu/drm/loongson/loongson_drv.c     |  13 +-
 drivers/gpu/drm/loongson/loongson_drv.h     |   7 +
 drivers/gpu/drm/loongson/loongson_encoder.c |  30 +++-
 drivers/gpu/drm/loongson/loongson_i2c.c     | 190 ++++++++++++++++++++
 drivers/gpu/drm/loongson/loongson_i2c.h     |  31 ++++
 6 files changed, 262 insertions(+), 10 deletions(-)
 create mode 100644 drivers/gpu/drm/loongson/loongson_i2c.c
 create mode 100644 drivers/gpu/drm/loongson/loongson_i2c.h

diff --git a/drivers/gpu/drm/loongson/Makefile 
b/drivers/gpu/drm/loongson/Makefile
index 534a64047fb6..4a5fab7d000b 100644
--- a/drivers/gpu/drm/loongson/Makefile
+++ b/drivers/gpu/drm/loongson/Makefile
@@ -9,5 +9,6 @@ loongson-y := loongson_connector.o \
        loongson_device.o \
        loongson_drv.o \
        loongson_encoder.o \
+       loongson_i2c.o \
        loongson_plane.o
 obj-$(CONFIG_DRM_LOONGSON) += loongson.o
diff --git a/drivers/gpu/drm/loongson/loongson_drv.c 
b/drivers/gpu/drm/loongson/loongson_drv.c
index c73232ecc977..dc3ccbb36569 100644
--- a/drivers/gpu/drm/loongson/loongson_drv.c
+++ b/drivers/gpu/drm/loongson/loongson_drv.c
@@ -20,9 +20,10 @@
 
 /* Interface history:
  * 0.1 - original.
+ * 0.2 - add i2c and connector detect.
  */
 #define DRIVER_MAJOR 0
-#define DRIVER_MINOR 1
+#define DRIVER_MINOR 2
 
 static const struct drm_mode_config_funcs loongson_mode_funcs = {
        .fb_create = drm_gem_fb_create,
@@ -86,6 +87,14 @@ static int loongson_device_init(struct drm_device *dev)
 
        ldev->num_crtc = 2;
 
+       ret = loongson_dc_gpio_init(ldev);
+       if (ret)
+               return ret;
+
+       ret = loongson_i2c_init(ldev);
+       if (ret)
+               return ret;
+
        drm_info(dev, "DC mmio base 0x%llx size 0x%llx io 0x%llx\n",
                 mmio_base, mmio_size, *(u64 *)ldev->io);
        drm_info(dev, "GPU vram start = 0x%x size = 0x%x\n",
@@ -94,7 +103,7 @@ static int loongson_device_init(struct drm_device *dev)
        return 0;
 }
 
-int loongson_modeset_init(struct loongson_device *ldev)
+static int loongson_modeset_init(struct loongson_device *ldev)
 {
        int i;
        int ret;
diff --git a/drivers/gpu/drm/loongson/loongson_drv.h 
b/drivers/gpu/drm/loongson/loongson_drv.h
index feb254ae8c32..e8ca0eac827c 100644
--- a/drivers/gpu/drm/loongson/loongson_drv.h
+++ b/drivers/gpu/drm/loongson/loongson_drv.h
@@ -8,6 +8,8 @@
 #include <drm/drm_gem_vram_helper.h>
 #include <drm/drm_bridge.h>
 
+#include "loongson_i2c.h"
+
 /* General customization:
  */
 #define DRIVER_AUTHOR "Loongson graphics driver team"
@@ -100,6 +102,8 @@ struct loongson_device {
        u32 num_crtc;
        struct loongson_mode_info mode_info[2];
        struct pci_dev *gpu_pdev; /* LS7A gpu device info */
+
+       struct loongson_i2c i2c_bus[DC_MAX_I2C_BUS];
 };
 
 static inline struct loongson_device *to_loongson_device(struct drm_device 
*dev)
@@ -119,6 +123,9 @@ int loongson_encoder_init(struct loongson_device *ldev, int 
index);
 /* plane */
 struct loongson_plane *loongson_plane_init(struct drm_device *dev, int index);
 
+/* i2c */
+int loongson_dc_gpio_init(struct loongson_device *ldev);
+
 /* device */
 u32 loongson_gpu_offset(struct drm_plane_state *state,
                        struct loongson_device *dev);
diff --git a/drivers/gpu/drm/loongson/loongson_encoder.c 
b/drivers/gpu/drm/loongson/loongson_encoder.c
index 984353c11816..18a0058b24a4 100644
--- a/drivers/gpu/drm/loongson/loongson_encoder.c
+++ b/drivers/gpu/drm/loongson/loongson_encoder.c
@@ -5,19 +5,31 @@
 
 #include "loongson_drv.h"
 
-static int loongson_bridge_get_modes(struct drm_bridge *bridge,
-                                    struct drm_connector *connector)
+enum drm_connector_status loongson_bridge_detect(struct drm_bridge *bridge)
 {
-       int count;
+       unsigned char start = 0x0;
+       struct i2c_msg msgs = {
+               .addr = DDC_ADDR,
+               .flags = 0,
+               .len = 1,
+               .buf = &start,
+       };
 
-       count = drm_add_modes_noedid(connector, 1920, 1080);
-       drm_set_preferred_mode(connector, 1024, 768);
+       if (i2c_transfer(bridge->ddc, &msgs, 1) != 1)
+               return connector_status_disconnected;
+       else
+               return connector_status_connected;
+}
 
-       return count;
+static struct edid *loongson_bridge_get_edid(struct drm_bridge *bridge,
+                                            struct drm_connector *connector)
+{
+       return drm_get_edid(connector, bridge->ddc);
 }
 
 static const struct drm_bridge_funcs loongson_encoder_bridge_funcs = {
-       .get_modes = loongson_bridge_get_modes,
+       .detect = loongson_bridge_detect,
+       .get_edid = loongson_bridge_get_edid,
        .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,
@@ -38,7 +50,9 @@ int loongson_encoder_init(struct loongson_device *ldev, int 
index)
        ldev->mode_info[index].encoder = lencoder;
 
        lencoder->bridge.funcs = &loongson_encoder_bridge_funcs;
-       lencoder->bridge.ops = DRM_BRIDGE_OP_MODES;
+       lencoder->bridge.ddc = ldev->i2c_bus[index].adapter;
+       lencoder->bridge.ops = DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID
+                              | DRM_BRIDGE_OP_MODES;
        if (index == 0)
                lencoder->bridge.type = DRM_MODE_CONNECTOR_VGA;
        else if (index == 1)
diff --git a/drivers/gpu/drm/loongson/loongson_i2c.c 
b/drivers/gpu/drm/loongson/loongson_i2c.c
new file mode 100644
index 000000000000..82cb24fa83f9
--- /dev/null
+++ b/drivers/gpu/drm/loongson/loongson_i2c.c
@@ -0,0 +1,190 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Copyright (C) 2022 Loongson Inc. */
+
+#include "loongson_drv.h"
+#include "loongson_i2c.h"
+
+static inline void dc_gpio_set_dir(struct loongson_device *ldev,
+                                  unsigned int pin, int input)
+{
+       u32 temp;
+
+       temp = ls7a_mm_rreg(ldev, LS7A_DC_GPIO_CFG_OFFSET);
+       if (input)
+               temp |= 1UL << pin;
+       else
+               temp &= ~(1UL << pin);
+
+       ls7a_mm_wreg(ldev, LS7A_DC_GPIO_CFG_OFFSET, temp);
+}
+
+static void dc_gpio_set_val(struct loongson_device *ldev, unsigned int pin,
+                           int high)
+{
+       u32 temp;
+
+       temp = ls7a_mm_rreg(ldev, LS7A_DC_GPIO_OUT_OFFSET);
+       if (high)
+               temp |= 1UL << pin;
+       else
+               temp &= ~(1UL << pin);
+
+       ls7a_mm_wreg(ldev, LS7A_DC_GPIO_OUT_OFFSET, temp);
+}
+
+static void loongson_i2c_set_data(void *i2c, int value)
+{
+       struct loongson_i2c *li2c = i2c;
+       struct loongson_device *ldev = li2c->ldev;
+       unsigned int pin = li2c->data;
+
+       if (value)
+               dc_gpio_set_dir(ldev, pin, 1);
+       else {
+               dc_gpio_set_val(ldev, pin, 0);
+               dc_gpio_set_dir(ldev, pin, 0);
+       }
+}
+
+static void loongson_i2c_set_clock(void *i2c, int value)
+{
+       struct loongson_i2c *li2c = i2c;
+       struct loongson_device *ldev = li2c->ldev;
+       unsigned int pin = li2c->clock;
+
+       if (value)
+               dc_gpio_set_dir(ldev, pin, 1);
+       else {
+               dc_gpio_set_val(ldev, pin, 0);
+               dc_gpio_set_dir(ldev, pin, 0);
+       }
+}
+
+static int loongson_i2c_get_data(void *i2c)
+{
+       int val;
+       struct loongson_i2c *li2c = i2c;
+       struct loongson_device *ldev = li2c->ldev;
+       unsigned int pin = li2c->data;
+
+       val = ls7a_mm_rreg(ldev, LS7A_DC_GPIO_IN_OFFSET);
+
+       return (val >> pin) & 1;
+}
+
+static int loongson_i2c_get_clock(void *i2c)
+{
+       int val;
+       struct loongson_i2c *li2c = i2c;
+       struct loongson_device *ldev = li2c->ldev;
+       unsigned int pin = li2c->clock;
+
+       val = ls7a_mm_rreg(ldev, LS7A_DC_GPIO_IN_OFFSET);
+
+       return (val >> pin) & 1;
+}
+
+static int loongson_i2c_create(struct loongson_device *ldev,
+                              struct loongson_i2c *li2c, const char *name)
+{
+       int ret;
+       unsigned int i2c_num;
+       struct drm_device *dev = &ldev->dev;
+       struct i2c_client *i2c_cli;
+       struct i2c_adapter *i2c_adapter;
+       struct i2c_algo_bit_data *i2c_algo_data;
+       const struct i2c_board_info i2c_info = {
+               .type = "ddc-dev",
+               .addr = DDC_ADDR,
+               .flags = I2C_CLASS_DDC,
+       };
+
+       i2c_num = li2c->i2c_id;
+       i2c_adapter = devm_kzalloc(dev->dev, sizeof(*i2c_adapter), GFP_KERNEL);
+       if (!i2c_adapter)
+               return -ENOMEM;
+
+       i2c_algo_data = devm_kzalloc(dev->dev, sizeof(*i2c_algo_data), 
GFP_KERNEL);
+       if (!i2c_algo_data) {
+               ret = -ENOMEM;
+               goto free_adapter;
+       }
+
+       i2c_adapter->owner = THIS_MODULE;
+       i2c_adapter->class = I2C_CLASS_DDC;
+       i2c_adapter->algo_data = i2c_algo_data;
+       i2c_adapter->dev.parent = dev->dev;
+       i2c_adapter->nr = -1;
+       snprintf(i2c_adapter->name, sizeof(i2c_adapter->name), "%s%d",
+                name, i2c_num);
+
+       li2c->data = i2c_num * 2;
+       li2c->clock = i2c_num * 2 + 1;
+       DRM_INFO("Created i2c-%d, sda=%d, scl=%d\n",
+                i2c_num, li2c->data, li2c->clock);
+
+       i2c_algo_data->setsda = loongson_i2c_set_data;
+       i2c_algo_data->setscl = loongson_i2c_set_clock;
+       i2c_algo_data->getsda = loongson_i2c_get_data;
+       i2c_algo_data->getscl = loongson_i2c_get_clock;
+       i2c_algo_data->udelay = DC_I2C_TON;
+       i2c_algo_data->timeout = usecs_to_jiffies(2200);
+
+       ret = i2c_bit_add_numbered_bus(i2c_adapter);
+       if (ret)
+               goto free_algo_data;
+
+       li2c->adapter = i2c_adapter;
+       i2c_algo_data->data = li2c;
+       i2c_set_adapdata(li2c->adapter, li2c);
+       li2c->ldev = ldev;
+       DRM_INFO("Register i2c algo-bit adapter [%s]\n", i2c_adapter->name);
+
+       i2c_cli = i2c_new_client_device(i2c_adapter, &i2c_info);
+       if (IS_ERR(i2c_cli)) {
+               ret = PTR_ERR(i2c_cli);
+               goto remove_i2c_adapter;
+       }
+
+       return 0;
+
+remove_i2c_adapter:
+       drm_err(dev, "Failed to create i2c client\n");
+       i2c_del_adapter(i2c_adapter);
+free_algo_data:
+       drm_err(dev, "Failed to register i2c adapter %s\n", i2c_adapter->name);
+       kfree(i2c_algo_data);
+free_adapter:
+       kfree(i2c_adapter);
+
+       return ret;
+}
+
+int loongson_dc_gpio_init(struct loongson_device *ldev)
+{
+       int pin;
+
+       /* set gpio dir output 0-3 */
+       for (pin = 0; pin < 4; pin++) {
+               dc_gpio_set_val(ldev, pin, 0);
+               dc_gpio_set_dir(ldev, pin, 0);
+       }
+
+       return 0;
+}
+
+int loongson_i2c_init(struct loongson_device *ldev)
+{
+       int ret;
+       int i;
+
+       for (i = 0; i < 2; i++) {
+               ldev->i2c_bus[1].i2c_id = i;
+               ret = loongson_i2c_create(ldev, &ldev->i2c_bus[i], DC_I2C_NAME);
+               if (ret)
+                       return ret;
+       }
+
+       return 0;
+}
+
diff --git a/drivers/gpu/drm/loongson/loongson_i2c.h 
b/drivers/gpu/drm/loongson/loongson_i2c.h
new file mode 100644
index 000000000000..c6c9c564fec4
--- /dev/null
+++ b/drivers/gpu/drm/loongson/loongson_i2c.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright (C) 2022 Loongson Inc. */
+
+#ifndef __LOONGSON_I2C_H__
+#define __LOONGSON_I2C_H__
+
+#include <linux/i2c.h>
+#include <linux/i2c-algo-bit.h>
+
+#include <drm/drm_edid.h>
+
+#define DC_I2C_TON 5
+#define DC_I2C_NAME "ls_dc_i2c"
+#define DC_MAX_I2C_BUS 2
+
+#define LS7A_DC_GPIO_CFG_OFFSET (0x1660)
+#define LS7A_DC_GPIO_IN_OFFSET (0x1650)
+#define LS7A_DC_GPIO_OUT_OFFSET (0x1650)
+
+struct loongson_device;
+struct loongson_i2c {
+       struct loongson_device *ldev;
+       struct i2c_adapter *adapter;
+       u32 data;
+       u32 clock;
+       u32 i2c_id;
+};
+
+int loongson_i2c_init(struct loongson_device *ldev);
+
+#endif /* __LOONGSON_I2C_H__ */
-- 
2.25.1

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