1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Copyright(c) 2016, Analogix Semiconductor.
4 *
5 * Based on anx7808 driver obtained from chromeos with copyright:
6 * Copyright(c) 2013, Google Inc.
7 */
8#include <linux/regmap.h>
9
10#include <drm/display/drm_dp_helper.h>
11#include <drm/drm.h>
12#include <drm/drm_print.h>
13
14#include "analogix-i2c-dptx.h"
15
16#define AUX_WAIT_TIMEOUT_MS 15
17#define AUX_CH_BUFFER_SIZE 16
18
19static int anx_i2c_dp_clear_bits(struct regmap *map, u8 reg, u8 mask)
20{
21 return regmap_update_bits(map, reg, mask, val: 0);
22}
23
24static bool anx_dp_aux_op_finished(struct regmap *map_dptx)
25{
26 unsigned int value;
27 int err;
28
29 err = regmap_read(map: map_dptx, SP_DP_AUX_CH_CTRL2_REG, val: &value);
30 if (err < 0)
31 return false;
32
33 return (value & SP_AUX_EN) == 0;
34}
35
36static int anx_dp_aux_wait(struct regmap *map_dptx)
37{
38 unsigned long timeout;
39 unsigned int status;
40 int err;
41
42 timeout = jiffies + msecs_to_jiffies(AUX_WAIT_TIMEOUT_MS) + 1;
43
44 while (!anx_dp_aux_op_finished(map_dptx)) {
45 if (time_after(jiffies, timeout)) {
46 if (!anx_dp_aux_op_finished(map_dptx)) {
47 DRM_ERROR("Timed out waiting AUX to finish\n");
48 return -ETIMEDOUT;
49 }
50
51 break;
52 }
53
54 usleep_range(min: 1000, max: 2000);
55 }
56
57 /* Read the AUX channel access status */
58 err = regmap_read(map: map_dptx, SP_AUX_CH_STATUS_REG, val: &status);
59 if (err < 0) {
60 DRM_ERROR("Failed to read from AUX channel: %d\n", err);
61 return err;
62 }
63
64 if (status & SP_AUX_STATUS) {
65 DRM_ERROR("Failed to wait for AUX channel (status: %02x)\n",
66 status);
67 return -ETIMEDOUT;
68 }
69
70 return 0;
71}
72
73static int anx_dp_aux_address(struct regmap *map_dptx, unsigned int addr)
74{
75 int err;
76
77 err = regmap_write(map: map_dptx, SP_AUX_ADDR_7_0_REG, val: addr & 0xff);
78 if (err)
79 return err;
80
81 err = regmap_write(map: map_dptx, SP_AUX_ADDR_15_8_REG,
82 val: (addr & 0xff00) >> 8);
83 if (err)
84 return err;
85
86 /*
87 * DP AUX CH Address Register #2, only update bits[3:0]
88 * [7:4] RESERVED
89 * [3:0] AUX_ADDR[19:16], Register control AUX CH address.
90 */
91 err = regmap_update_bits(map: map_dptx, SP_AUX_ADDR_19_16_REG,
92 SP_AUX_ADDR_19_16_MASK,
93 val: (addr & 0xf0000) >> 16);
94
95 if (err)
96 return err;
97
98 return 0;
99}
100
101ssize_t anx_dp_aux_transfer(struct regmap *map_dptx,
102 struct drm_dp_aux_msg *msg)
103{
104 u8 ctrl1 = msg->request;
105 u8 ctrl2 = SP_AUX_EN;
106 u8 *buffer = msg->buffer;
107 int err;
108
109 /* The DP AUX transmit and receive buffer has 16 bytes. */
110 if (WARN_ON(msg->size > AUX_CH_BUFFER_SIZE))
111 return -E2BIG;
112
113 /* Zero-sized messages specify address-only transactions. */
114 if (msg->size < 1)
115 ctrl2 |= SP_ADDR_ONLY;
116 else /* For non-zero-sized set the length field. */
117 ctrl1 |= (msg->size - 1) << SP_AUX_LENGTH_SHIFT;
118
119 if ((msg->size > 0) && ((msg->request & DP_AUX_I2C_READ) == 0)) {
120 /* When WRITE | MOT write values to data buffer */
121 err = regmap_bulk_write(map: map_dptx,
122 SP_DP_BUF_DATA0_REG, val: buffer,
123 val_count: msg->size);
124 if (err)
125 return err;
126 }
127
128 /* Write address and request */
129 err = anx_dp_aux_address(map_dptx, addr: msg->address);
130 if (err)
131 return err;
132
133 err = regmap_write(map: map_dptx, SP_DP_AUX_CH_CTRL1_REG, val: ctrl1);
134 if (err)
135 return err;
136
137 /* Start transaction */
138 err = regmap_update_bits(map: map_dptx, SP_DP_AUX_CH_CTRL2_REG,
139 SP_ADDR_ONLY | SP_AUX_EN, val: ctrl2);
140 if (err)
141 return err;
142
143 err = anx_dp_aux_wait(map_dptx);
144 if (err)
145 return err;
146
147 msg->reply = DP_AUX_I2C_REPLY_ACK;
148
149 if ((msg->size > 0) && (msg->request & DP_AUX_I2C_READ)) {
150 /* Read values from data buffer */
151 err = regmap_bulk_read(map: map_dptx,
152 SP_DP_BUF_DATA0_REG, val: buffer,
153 val_count: msg->size);
154 if (err)
155 return err;
156 }
157
158 err = anx_i2c_dp_clear_bits(map: map_dptx, SP_DP_AUX_CH_CTRL2_REG,
159 SP_ADDR_ONLY);
160 if (err)
161 return err;
162
163 return msg->size;
164}
165EXPORT_SYMBOL_GPL(anx_dp_aux_transfer);
166

source code of linux/drivers/gpu/drm/bridge/analogix/analogix-i2c-dptx.c