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->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 }
100