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  */
18 static 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(st->map, st->reg->sample_rate_div, 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(st->map, st->reg->user_ctrl, user_ctrl);
36 	if (ret)
37 		goto error_restore_rate;
38 
39 	/* wait for xfer: 1 period + half-period margin */
40 	msleep(period_ms + period_ms / 2);
41 
42 	/* stop i2c master */
43 	user_ctrl = st->chip_config.user_ctrl;
44 	ret = regmap_write(st->map, st->reg->user_ctrl, 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(st->map, st->reg->sample_rate_div, d);
51 	if (ret)
52 		goto error_restore_rate;
53 
54 	return 0;
55 
56 error_stop_i2c:
57 	regmap_write(st->map, st->reg->user_ctrl, st->chip_config.user_ctrl);
58 error_restore_rate:
59 	regmap_write(st->map, st->reg->sample_rate_div, 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  */
69 int inv_mpu_aux_init(const struct inv_mpu6050_state *st)
70 {
71 	unsigned int val;
72 	int ret;
73 
74 	/* configure i2c master */
75 	val = INV_MPU6050_BITS_I2C_MST_CLK_400KHZ |
76 			INV_MPU6050_BIT_WAIT_FOR_ES;
77 	ret = regmap_write(st->map, INV_MPU6050_REG_I2C_MST_CTRL, val);
78 	if (ret)
79 		return ret;
80 
81 	/* configure i2c master delay */
82 	ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV4_CTRL, 0);
83 	if (ret)
84 		return ret;
85 
86 	val = INV_MPU6050_BIT_I2C_SLV0_DLY_EN |
87 			INV_MPU6050_BIT_I2C_SLV1_DLY_EN |
88 			INV_MPU6050_BIT_I2C_SLV2_DLY_EN |
89 			INV_MPU6050_BIT_I2C_SLV3_DLY_EN |
90 			INV_MPU6050_BIT_DELAY_ES_SHADOW;
91 	return regmap_write(st->map, INV_MPU6050_REG_I2C_MST_DELAY_CTRL, val);
92 }
93 
94 /**
95  * inv_mpu_aux_read() - read register function for i2c auxiliary bus
96  * @st: driver internal state.
97  * @addr: chip i2c Address
98  * @reg: chip register address
99  * @val: buffer for storing read bytes
100  * @size: number of bytes to read
101  *
102  *  Returns 0 on success, a negative error code otherwise.
103  */
104 int inv_mpu_aux_read(const struct inv_mpu6050_state *st, uint8_t addr,
105 		     uint8_t reg, uint8_t *val, size_t size)
106 {
107 	unsigned int status;
108 	int ret;
109 
110 	if (size > 0x0F)
111 		return -EINVAL;
112 
113 	/* setup i2c SLV0 control: i2c addr, register, enable + size */
114 	ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_ADDR(0),
115 			   INV_MPU6050_BIT_I2C_SLV_RNW | addr);
116 	if (ret)
117 		return ret;
118 	ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_REG(0), reg);
119 	if (ret)
120 		return ret;
121 	ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0),
122 			   INV_MPU6050_BIT_SLV_EN | size);
123 	if (ret)
124 		return ret;
125 
126 	/* do i2c xfer */
127 	ret = inv_mpu_i2c_master_xfer(st);
128 	if (ret)
129 		goto error_disable_i2c;
130 
131 	/* disable i2c slave */
132 	ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0), 0);
133 	if (ret)
134 		goto error_disable_i2c;
135 
136 	/* check i2c status */
137 	ret = regmap_read(st->map, INV_MPU6050_REG_I2C_MST_STATUS, &status);
138 	if (ret)
139 		return ret;
140 	if (status & INV_MPU6050_BIT_I2C_SLV0_NACK)
141 		return -EIO;
142 
143 	/* read data in registers */
144 	return regmap_bulk_read(st->map, INV_MPU6050_REG_EXT_SENS_DATA,
145 				val, size);
146 
147 error_disable_i2c:
148 	regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0), 0);
149 	return ret;
150 }
151 
152 /**
153  * inv_mpu_aux_write() - write register function for i2c auxiliary bus
154  * @st: driver internal state.
155  * @addr: chip i2c Address
156  * @reg: chip register address
157  * @val: 1 byte value to write
158  *
159  *  Returns 0 on success, a negative error code otherwise.
160  */
161 int inv_mpu_aux_write(const struct inv_mpu6050_state *st, uint8_t addr,
162 		      uint8_t reg, uint8_t val)
163 {
164 	unsigned int status;
165 	int ret;
166 
167 	/* setup i2c SLV0 control: i2c addr, register, value, enable + size */
168 	ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_ADDR(0), addr);
169 	if (ret)
170 		return ret;
171 	ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_REG(0), reg);
172 	if (ret)
173 		return ret;
174 	ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_DO(0), val);
175 	if (ret)
176 		return ret;
177 	ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0),
178 			   INV_MPU6050_BIT_SLV_EN | 1);
179 	if (ret)
180 		return ret;
181 
182 	/* do i2c xfer */
183 	ret = inv_mpu_i2c_master_xfer(st);
184 	if (ret)
185 		goto error_disable_i2c;
186 
187 	/* disable i2c slave */
188 	ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0), 0);
189 	if (ret)
190 		goto error_disable_i2c;
191 
192 	/* check i2c status */
193 	ret = regmap_read(st->map, INV_MPU6050_REG_I2C_MST_STATUS, &status);
194 	if (ret)
195 		return ret;
196 	if (status & INV_MPU6050_BIT_I2C_SLV0_NACK)
197 		return -EIO;
198 
199 	return 0;
200 
201 error_disable_i2c:
202 	regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0), 0);
203 	return ret;
204 }
205