drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_i2c.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* Hisilicon Hibmc SoC drm driver
   3  *
   4  * Based on the bochs drm driver.
   5  *
   6  * Copyright (c) 2016 Huawei Limited.
   7  *
   8  * Author:
   9  *      Tian Tao <tiantao6@hisilicon.com>
  10  */
  11
  12 #include <linux/delay.h>
  13 #include <linux/pci.h>
  14
  15 #include <drm/drm_atomic_helper.h>
  16 #include <drm/drm_probe_helper.h>
  17
  18 #include "hibmc_drm_drv.h"
  19
  20 #define GPIO_DATA               0x0802A0
  21 #define GPIO_DATA_DIRECTION     0x0802A4
  22
  23 #define I2C_SCL_MASK            BIT(0)
  24 #define I2C_SDA_MASK            BIT(1)
  25
  26 static void hibmc_set_i2c_signal(void *data, u32 mask, int value)
  27 {
  28         struct hibmc_connector *hibmc_connector = data;
  29         struct hibmc_drm_private *priv = to_hibmc_drm_private(hibmc_connector->base.dev);
  30         u32 tmp_dir = readl(priv->mmio + GPIO_DATA_DIRECTION);
  31
  32         if (value) {
  33                 tmp_dir &= ~mask;
  34                 writel(tmp_dir, priv->mmio + GPIO_DATA_DIRECTION);
  35         } else {
  36                 u32 tmp_data = readl(priv->mmio + GPIO_DATA);
  37
  38                 tmp_data &= ~mask;
  39                 writel(tmp_data, priv->mmio + GPIO_DATA);
  40
  41                 tmp_dir |= mask;
  42                 writel(tmp_dir, priv->mmio + GPIO_DATA_DIRECTION);
  43         }
  44 }
  45
  46 static int hibmc_get_i2c_signal(void *data, u32 mask)
  47 {
  48         struct hibmc_connector *hibmc_connector = data;
  49         struct hibmc_drm_private *priv = to_hibmc_drm_private(hibmc_connector->base.dev);
  50         u32 tmp_dir = readl(priv->mmio + GPIO_DATA_DIRECTION);
  51
  52         if ((tmp_dir & mask) != mask) {
  53                 tmp_dir &= ~mask;
  54                 writel(tmp_dir, priv->mmio + GPIO_DATA_DIRECTION);
  55         }
  56
  57         return (readl(priv->mmio + GPIO_DATA) & mask) ? 1 : 0;
  58 }
  59
  60 static void hibmc_ddc_setsda(void *data, int state)
  61 {
  62         hibmc_set_i2c_signal(data, I2C_SDA_MASK, state);
  63 }
  64
  65 static void hibmc_ddc_setscl(void *data, int state)
  66 {
  67         hibmc_set_i2c_signal(data, I2C_SCL_MASK, state);
  68 }
  69
  70 static int hibmc_ddc_getsda(void *data)
  71 {
  72         return hibmc_get_i2c_signal(data, I2C_SDA_MASK);
  73 }
  74
  75 static int hibmc_ddc_getscl(void *data)
  76 {
  77         return hibmc_get_i2c_signal(data, I2C_SCL_MASK);
  78 }
  79
  80 int hibmc_ddc_create(struct drm_device *drm_dev,
  81                      struct hibmc_connector *connector)
  82 {
  83         connector->adapter.owner = THIS_MODULE;
  84         connector->adapter.class = I2C_CLASS_DDC;
  85         snprintf(connector->adapter.name, I2C_NAME_SIZE, "HIS i2c bit bus");
  86         connector->adapter.dev.parent = &drm_dev->pdev->dev;
  87         i2c_set_adapdata(&connector->adapter, connector);
  88         connector->adapter.algo_data = &connector->bit_data;
  89
  90         connector->bit_data.udelay = 20;
  91         connector->bit_data.timeout = usecs_to_jiffies(2000);
  92         connector->bit_data.data = connector;
  93         connector->bit_data.setsda = hibmc_ddc_setsda;
  94         connector->bit_data.setscl = hibmc_ddc_setscl;
  95         connector->bit_data.getsda = hibmc_ddc_getsda;
  96         connector->bit_data.getscl = hibmc_ddc_getscl;
  97
  98         return i2c_bit_add_bus(&connector->adapter);
  99 }