1// SPDX-License-Identifier: GPL-2.0-or-later
2
3#include <linux/err.h>
4#include <linux/i2c.h>
5#include <linux/init.h>
6#include <linux/kernel.h>
7#include <linux/module.h>
8#include <linux/pmbus.h>
9#include "pmbus.h"
10
11/* LTC4286 register */
12#define LTC4286_MFR_CONFIG1	0xF2
13
14/* LTC4286 configuration */
15#define VRANGE_SELECT_BIT	BIT(1)
16
17#define LTC4286_MFR_ID_SIZE	3
18
19/*
20 * Initialize the MBR as default settings which is referred to LTC4286 datasheet
21 * (March 22, 2022 version) table 3 page 16
22 */
23static struct pmbus_driver_info ltc4286_info = {
24	.pages = 1,
25	.format[PSC_VOLTAGE_IN] = direct,
26	.format[PSC_VOLTAGE_OUT] = direct,
27	.format[PSC_CURRENT_OUT] = direct,
28	.format[PSC_POWER] = direct,
29	.format[PSC_TEMPERATURE] = direct,
30	.m[PSC_VOLTAGE_IN] = 32,
31	.b[PSC_VOLTAGE_IN] = 0,
32	.R[PSC_VOLTAGE_IN] = 1,
33	.m[PSC_VOLTAGE_OUT] = 32,
34	.b[PSC_VOLTAGE_OUT] = 0,
35	.R[PSC_VOLTAGE_OUT] = 1,
36	.m[PSC_CURRENT_OUT] = 1024,
37	.b[PSC_CURRENT_OUT] = 0,
38	/*
39	 * The rsense value used in MBR formula in LTC4286 datasheet should be ohm unit.
40	 * However, the rsense value that user input is micro ohm.
41	 * Thus, the MBR setting which involves rsense should be shifted by 6 digits.
42	 */
43	.R[PSC_CURRENT_OUT] = 3 - 6,
44	.m[PSC_POWER] = 1,
45	.b[PSC_POWER] = 0,
46	/*
47	 * The rsense value used in MBR formula in LTC4286 datasheet should be ohm unit.
48	 * However, the rsense value that user input is micro ohm.
49	 * Thus, the MBR setting which involves rsense should be shifted by 6 digits.
50	 */
51	.R[PSC_POWER] = 4 - 6,
52	.m[PSC_TEMPERATURE] = 1,
53	.b[PSC_TEMPERATURE] = 273,
54	.R[PSC_TEMPERATURE] = 0,
55	.func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT |
56		   PMBUS_HAVE_PIN | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_VOUT |
57		   PMBUS_HAVE_STATUS_IOUT | PMBUS_HAVE_STATUS_TEMP,
58};
59
60static const struct i2c_device_id ltc4286_id[] = {
61	{ "ltc4286", 0 },
62	{ "ltc4287", 1 },
63	{}
64};
65MODULE_DEVICE_TABLE(i2c, ltc4286_id);
66
67static int ltc4286_probe(struct i2c_client *client)
68{
69	int ret;
70	const struct i2c_device_id *mid;
71	u8 block_buffer[I2C_SMBUS_BLOCK_MAX + 1];
72	struct pmbus_driver_info *info;
73	u32 rsense;
74	int vrange_nval, vrange_oval;
75
76	ret = i2c_smbus_read_block_data(client, PMBUS_MFR_ID, block_buffer);
77	if (ret < 0) {
78		return dev_err_probe(&client->dev, ret,
79				     "Failed to read manufacturer id\n");
80	}
81
82	/*
83	 * Refer to ltc4286 datasheet page 20
84	 * the manufacturer id is LTC
85	 */
86	if (ret != LTC4286_MFR_ID_SIZE ||
87	    strncmp(block_buffer, "LTC", LTC4286_MFR_ID_SIZE)) {
88		return dev_err_probe(&client->dev, -ENODEV,
89				     "Manufacturer id mismatch\n");
90	}
91
92	ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, block_buffer);
93	if (ret < 0) {
94		return dev_err_probe(&client->dev, ret,
95				     "Failed to read manufacturer model\n");
96	}
97
98	for (mid = ltc4286_id; mid->name[0]; mid++) {
99		if (!strncasecmp(mid->name, block_buffer, strlen(mid->name)))
100			break;
101	}
102	if (!mid->name[0])
103		return dev_err_probe(&client->dev, -ENODEV,
104				     "Unsupported device\n");
105
106	if (of_property_read_u32(client->dev.of_node,
107				 "shunt-resistor-micro-ohms", &rsense))
108		rsense = 300; /* 0.3 mOhm if not set via DT */
109
110	if (rsense == 0)
111		return -EINVAL;
112
113	/* Check for the latter MBR value won't overflow */
114	if (rsense > (INT_MAX / 1024))
115		return -EINVAL;
116
117	info = devm_kmemdup(&client->dev, &ltc4286_info, sizeof(*info),
118			    GFP_KERNEL);
119	if (!info)
120		return -ENOMEM;
121
122	/* Check MFR1 CONFIG register bit 1 VRANGE_SELECT before driver loading */
123	vrange_oval = i2c_smbus_read_word_data(client, LTC4286_MFR_CONFIG1);
124	if (vrange_oval < 0)
125		return dev_err_probe(&client->dev, vrange_oval,
126				     "Failed to read manufacturer configuration one\n");
127	vrange_nval = vrange_oval;
128
129	if (device_property_read_bool(&client->dev, "adi,vrange-low-enable")) {
130		vrange_nval &=
131			~VRANGE_SELECT_BIT; /* VRANGE_SELECT = 0, 25.6 volts */
132
133		info->m[PSC_VOLTAGE_IN] = 128;
134		info->m[PSC_VOLTAGE_OUT] = 128;
135		info->m[PSC_POWER] = 4 * rsense;
136	} else {
137		vrange_nval |=
138			VRANGE_SELECT_BIT; /* VRANGE_SELECT = 1, 102.4 volts */
139
140		info->m[PSC_POWER] = rsense;
141	}
142	if (vrange_nval != vrange_oval) {
143		/* Set MFR1 CONFIG register bit 1 VRANGE_SELECT */
144		ret = i2c_smbus_write_word_data(client, LTC4286_MFR_CONFIG1,
145						vrange_nval);
146		if (ret < 0)
147			return dev_err_probe(&client->dev, ret,
148					     "Failed to set vrange\n");
149	}
150
151	info->m[PSC_CURRENT_OUT] = 1024 * rsense;
152
153	return pmbus_do_probe(client, info);
154}
155
156static const struct of_device_id ltc4286_of_match[] = {
157	{ .compatible = "lltc,ltc4286" },
158	{ .compatible = "lltc,ltc4287" },
159	{}
160};
161
162static struct i2c_driver ltc4286_driver = {
163	.driver = {
164		.name = "ltc4286",
165		.of_match_table = ltc4286_of_match,
166	},
167	.probe = ltc4286_probe,
168	.id_table = ltc4286_id,
169};
170
171module_i2c_driver(ltc4286_driver);
172
173MODULE_AUTHOR("Delphine CC Chiu <Delphine_CC_Chiu@wiwynn.com>");
174MODULE_DESCRIPTION("PMBUS driver for LTC4286 and compatibles");
175MODULE_LICENSE("GPL");
176