1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2019 TDK-InvenSense, Inc.
4 */
5
6#include <linux/kernel.h>
7#include <linux/device.h>
8#include <linux/regmap.h>
9#include <linux/delay.h>
10
11#include "inv_mpu_aux.h"
12#include "inv_mpu_iio.h"
13
14/*
15 * i2c master auxiliary bus transfer function.
16 * Requires the i2c operations to be correctly setup before.
17 */
18static int inv_mpu_i2c_master_xfer(const struct inv_mpu6050_state *st)
19{
20 /* use 50hz frequency for xfer */
21 const unsigned int freq = 50;
22 const unsigned int period_ms = 1000 / freq;
23 uint8_t d;
24 unsigned int user_ctrl;
25 int ret;
26
27 /* set sample rate */
28 d = INV_MPU6050_FIFO_RATE_TO_DIVIDER(freq);
29 ret = regmap_write(map: st->map, reg: st->reg->sample_rate_div, val: d);
30 if (ret)
31 return ret;
32
33 /* start i2c master */
34 user_ctrl = st->chip_config.user_ctrl | INV_MPU6050_BIT_I2C_MST_EN;
35 ret = regmap_write(map: st->map, reg: st->reg->user_ctrl, val: user_ctrl);
36 if (ret)
37 goto error_restore_rate;
38
39 /* wait for xfer: 1 period + half-period margin */
40 msleep(msecs: period_ms + period_ms / 2);
41
42 /* stop i2c master */
43 user_ctrl = st->chip_config.user_ctrl;
44 ret = regmap_write(map: st->map, reg: st->reg->user_ctrl, val: user_ctrl);
45 if (ret)
46 goto error_stop_i2c;
47
48 /* restore sample rate */
49 d = st->chip_config.divider;
50 ret = regmap_write(map: st->map, reg: st->reg->sample_rate_div, val: d);
51 if (ret)
52 goto error_restore_rate;
53
54 return 0;
55
56error_stop_i2c:
57 regmap_write(map: st->map, reg: st->reg->user_ctrl, val: st->chip_config.user_ctrl);
58error_restore_rate:
59 regmap_write(map: st->map, reg: st->reg->sample_rate_div, val: st->chip_config.divider);
60 return ret;
61}
62
63/**
64 * inv_mpu_aux_init() - init i2c auxiliary bus
65 * @st: driver internal state
66 *
67 * Returns 0 on success, a negative error code otherwise.
68 */
69int inv_mpu_aux_init(const struct inv_mpu6050_state *st)
70{
71 unsigned int val;
72 int ret;
73
74 /*
75 * Code based on the vendor Linux kernel v3.0,
76 * the exact meaning is unknown.
77 */
78 if (st->chip_type == INV_MPU9150) {
79 unsigned int mask = BIT(7);
80
81 val = st->level_shifter ? mask : 0;
82 ret = regmap_update_bits(map: st->map, reg: 0x1, mask, val);
83 if (ret)
84 return ret;
85 }
86
87 /* configure i2c master */
88 val = INV_MPU6050_BITS_I2C_MST_CLK_400KHZ |
89 INV_MPU6050_BIT_WAIT_FOR_ES;
90 ret = regmap_write(map: st->map, INV_MPU6050_REG_I2C_MST_CTRL, val);
91 if (ret)
92 return ret;
93
94 /* configure i2c master delay */
95 ret = regmap_write(map: st->map, INV_MPU6050_REG_I2C_SLV4_CTRL, val: 0);
96 if (ret)
97 return ret;
98
99 val = INV_MPU6050_BIT_I2C_SLV0_DLY_EN |
100 INV_MPU6050_BIT_I2C_SLV1_DLY_EN |
101 INV_MPU6050_BIT_I2C_SLV2_DLY_EN |
102 INV_MPU6050_BIT_I2C_SLV3_DLY_EN |
103 INV_MPU6050_BIT_DELAY_ES_SHADOW;
104 return regmap_write(map: st->map, INV_MPU6050_REG_I2C_MST_DELAY_CTRL, val);
105}
106
107/**
108 * inv_mpu_aux_read() - read register function for i2c auxiliary bus
109 * @st: driver internal state.
110 * @addr: chip i2c Address
111 * @reg: chip register address
112 * @val: buffer for storing read bytes
113 * @size: number of bytes to read
114 *
115 * Returns 0 on success, a negative error code otherwise.
116 */
117int inv_mpu_aux_read(const struct inv_mpu6050_state *st, uint8_t addr,
118 uint8_t reg, uint8_t *val, size_t size)
119{
120 unsigned int status;
121 int ret;
122
123 if (size > 0x0F)
124 return -EINVAL;
125
126 /* setup i2c SLV0 control: i2c addr, register, enable + size */
127 ret = regmap_write(map: st->map, INV_MPU6050_REG_I2C_SLV_ADDR(0),
128 INV_MPU6050_BIT_I2C_SLV_RNW | addr);
129 if (ret)
130 return ret;
131 ret = regmap_write(map: st->map, INV_MPU6050_REG_I2C_SLV_REG(0), val: reg);
132 if (ret)
133 return ret;
134 ret = regmap_write(map: st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0),
135 INV_MPU6050_BIT_SLV_EN | size);
136 if (ret)
137 return ret;
138
139 /* do i2c xfer */
140 ret = inv_mpu_i2c_master_xfer(st);
141 if (ret)
142 goto error_disable_i2c;
143
144 /* disable i2c slave */
145 ret = regmap_write(map: st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0), val: 0);
146 if (ret)
147 goto error_disable_i2c;
148
149 /* check i2c status */
150 ret = regmap_read(map: st->map, INV_MPU6050_REG_I2C_MST_STATUS, val: &status);
151 if (ret)
152 return ret;
153 if (status & INV_MPU6050_BIT_I2C_SLV0_NACK)
154 return -EIO;
155
156 /* read data in registers */
157 return regmap_bulk_read(map: st->map, INV_MPU6050_REG_EXT_SENS_DATA,
158 val, val_count: size);
159
160error_disable_i2c:
161 regmap_write(map: st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0), val: 0);
162 return ret;
163}
164
165/**
166 * inv_mpu_aux_write() - write register function for i2c auxiliary bus
167 * @st: driver internal state.
168 * @addr: chip i2c Address
169 * @reg: chip register address
170 * @val: 1 byte value to write
171 *
172 * Returns 0 on success, a negative error code otherwise.
173 */
174int inv_mpu_aux_write(const struct inv_mpu6050_state *st, uint8_t addr,
175 uint8_t reg, uint8_t val)
176{
177 unsigned int status;
178 int ret;
179
180 /* setup i2c SLV0 control: i2c addr, register, value, enable + size */
181 ret = regmap_write(map: st->map, INV_MPU6050_REG_I2C_SLV_ADDR(0), val: addr);
182 if (ret)
183 return ret;
184 ret = regmap_write(map: st->map, INV_MPU6050_REG_I2C_SLV_REG(0), val: reg);
185 if (ret)
186 return ret;
187 ret = regmap_write(map: st->map, INV_MPU6050_REG_I2C_SLV_DO(0), val);
188 if (ret)
189 return ret;
190 ret = regmap_write(map: st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0),
191 INV_MPU6050_BIT_SLV_EN | 1);
192 if (ret)
193 return ret;
194
195 /* do i2c xfer */
196 ret = inv_mpu_i2c_master_xfer(st);
197 if (ret)
198 goto error_disable_i2c;
199
200 /* disable i2c slave */
201 ret = regmap_write(map: st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0), val: 0);
202 if (ret)
203 goto error_disable_i2c;
204
205 /* check i2c status */
206 ret = regmap_read(map: st->map, INV_MPU6050_REG_I2C_MST_STATUS, val: &status);
207 if (ret)
208 return ret;
209 if (status & INV_MPU6050_BIT_I2C_SLV0_NACK)
210 return -EIO;
211
212 return 0;
213
214error_disable_i2c:
215 regmap_write(map: st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0), val: 0);
216 return ret;
217}
218

source code of linux/drivers/iio/imu/inv_mpu6050/inv_mpu_aux.c