1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Hardware monitoring driver for Maxim MAX15301 4 * 5 * Copyright (c) 2021 Flextronics International Sweden AB 6 * 7 * Even though the specification does not specifically mention it, 8 * extensive empirical testing has revealed that auto-detection of 9 * limit-registers will fail in a random fashion unless the delay 10 * parameter is set to above about 80us. The default delay is set 11 * to 100us to include some safety margin. 12 */ 13 14 #include <linux/kernel.h> 15 #include <linux/module.h> 16 #include <linux/init.h> 17 #include <linux/err.h> 18 #include <linux/slab.h> 19 #include <linux/i2c.h> 20 #include <linux/ktime.h> 21 #include <linux/delay.h> 22 #include <linux/pmbus.h> 23 #include "pmbus.h" 24 25 static const struct i2c_device_id max15301_id[] = { 26 { "bmr461" }, 27 { "max15301" }, 28 {} 29 }; 30 MODULE_DEVICE_TABLE(i2c, max15301_id); 31 32 struct max15301_data { 33 int id; 34 ktime_t access; /* Chip access time */ 35 int delay; /* Delay between chip accesses in us */ 36 struct pmbus_driver_info info; 37 }; 38 39 #define to_max15301_data(x) container_of(x, struct max15301_data, info) 40 41 #define MAX15301_WAIT_TIME 100 /* us */ 42 43 static ushort delay = MAX15301_WAIT_TIME; 44 module_param(delay, ushort, 0644); 45 MODULE_PARM_DESC(delay, "Delay between chip accesses in us"); 46 47 static struct max15301_data max15301_data = { 48 .info = { 49 .pages = 1, 50 .func[0] = PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT 51 | PMBUS_HAVE_VIN | PMBUS_HAVE_STATUS_INPUT 52 | PMBUS_HAVE_TEMP | PMBUS_HAVE_TEMP2 53 | PMBUS_HAVE_STATUS_TEMP 54 | PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT, 55 } 56 }; 57 58 /* This chip needs a delay between accesses */ 59 static inline void max15301_wait(const struct max15301_data *data) 60 { 61 if (data->delay) { 62 s64 delta = ktime_us_delta(ktime_get(), data->access); 63 64 if (delta < data->delay) 65 udelay(data->delay - delta); 66 } 67 } 68 69 static int max15301_read_word_data(struct i2c_client *client, int page, 70 int phase, int reg) 71 { 72 const struct pmbus_driver_info *info = pmbus_get_driver_info(client); 73 struct max15301_data *data = to_max15301_data(info); 74 int ret; 75 76 if (page > 0) 77 return -ENXIO; 78 79 if (reg >= PMBUS_VIRT_BASE) 80 return -ENXIO; 81 82 max15301_wait(data); 83 ret = pmbus_read_word_data(client, page, phase, reg); 84 data->access = ktime_get(); 85 86 return ret; 87 } 88 89 static int max15301_read_byte_data(struct i2c_client *client, int page, int reg) 90 { 91 const struct pmbus_driver_info *info = pmbus_get_driver_info(client); 92 struct max15301_data *data = to_max15301_data(info); 93 int ret; 94 95 if (page > 0) 96 return -ENXIO; 97 98 max15301_wait(data); 99 ret = pmbus_read_byte_data(client, page, reg); 100 data->access = ktime_get(); 101 102 return ret; 103 } 104 105 static int max15301_write_word_data(struct i2c_client *client, int page, int reg, 106 u16 word) 107 { 108 const struct pmbus_driver_info *info = pmbus_get_driver_info(client); 109 struct max15301_data *data = to_max15301_data(info); 110 int ret; 111 112 if (page > 0) 113 return -ENXIO; 114 115 if (reg >= PMBUS_VIRT_BASE) 116 return -ENXIO; 117 118 max15301_wait(data); 119 ret = pmbus_write_word_data(client, page, reg, word); 120 data->access = ktime_get(); 121 122 return ret; 123 } 124 125 static int max15301_write_byte(struct i2c_client *client, int page, u8 value) 126 { 127 const struct pmbus_driver_info *info = pmbus_get_driver_info(client); 128 struct max15301_data *data = to_max15301_data(info); 129 int ret; 130 131 if (page > 0) 132 return -ENXIO; 133 134 max15301_wait(data); 135 ret = pmbus_write_byte(client, page, value); 136 data->access = ktime_get(); 137 138 return ret; 139 } 140 141 static int max15301_probe(struct i2c_client *client) 142 { 143 int status; 144 u8 device_id[I2C_SMBUS_BLOCK_MAX + 1]; 145 const struct i2c_device_id *mid; 146 struct pmbus_driver_info *info = &max15301_data.info; 147 148 if (!i2c_check_functionality(client->adapter, 149 I2C_FUNC_SMBUS_READ_BYTE_DATA 150 | I2C_FUNC_SMBUS_BLOCK_DATA)) 151 return -ENODEV; 152 153 status = i2c_smbus_read_block_data(client, PMBUS_IC_DEVICE_ID, device_id); 154 if (status < 0) { 155 dev_err(&client->dev, "Failed to read Device Id\n"); 156 return status; 157 } 158 for (mid = max15301_id; mid->name[0]; mid++) { 159 if (!strncasecmp(mid->name, device_id, strlen(mid->name))) 160 break; 161 } 162 if (!mid->name[0]) { 163 dev_err(&client->dev, "Unsupported device\n"); 164 return -ENODEV; 165 } 166 167 max15301_data.delay = delay; 168 169 info->read_byte_data = max15301_read_byte_data; 170 info->read_word_data = max15301_read_word_data; 171 info->write_byte = max15301_write_byte; 172 info->write_word_data = max15301_write_word_data; 173 174 return pmbus_do_probe(client, info); 175 } 176 177 static struct i2c_driver max15301_driver = { 178 .driver = { 179 .name = "max15301", 180 }, 181 .probe = max15301_probe, 182 .id_table = max15301_id, 183 }; 184 185 module_i2c_driver(max15301_driver); 186 187 MODULE_AUTHOR("Erik Rosen <erik.rosen@metormote.com>"); 188 MODULE_DESCRIPTION("PMBus driver for Maxim MAX15301"); 189 MODULE_LICENSE("GPL"); 190 MODULE_IMPORT_NS(PMBUS); 191