1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * sbrmi.c - hwmon driver for a SB-RMI mailbox 4 * compliant AMD SoC device. 5 * 6 * Copyright (C) 2020-2021 Advanced Micro Devices, Inc. 7 */ 8 9 #include <linux/delay.h> 10 #include <linux/err.h> 11 #include <linux/hwmon.h> 12 #include <linux/i2c.h> 13 #include <linux/init.h> 14 #include <linux/module.h> 15 #include <linux/mutex.h> 16 #include <linux/of.h> 17 18 /* Do not allow setting negative power limit */ 19 #define SBRMI_PWR_MIN 0 20 /* Mask for Status Register bit[1] */ 21 #define SW_ALERT_MASK 0x2 22 23 /* Software Interrupt for triggering */ 24 #define START_CMD 0x80 25 #define TRIGGER_MAILBOX 0x01 26 27 /* 28 * SB-RMI supports soft mailbox service request to MP1 (power management 29 * firmware) through SBRMI inbound/outbound message registers. 30 * SB-RMI message IDs 31 */ 32 enum sbrmi_msg_id { 33 SBRMI_READ_PKG_PWR_CONSUMPTION = 0x1, 34 SBRMI_WRITE_PKG_PWR_LIMIT, 35 SBRMI_READ_PKG_PWR_LIMIT, 36 SBRMI_READ_PKG_MAX_PWR_LIMIT, 37 }; 38 39 /* SB-RMI registers */ 40 enum sbrmi_reg { 41 SBRMI_CTRL = 0x01, 42 SBRMI_STATUS, 43 SBRMI_OUTBNDMSG0 = 0x30, 44 SBRMI_OUTBNDMSG1, 45 SBRMI_OUTBNDMSG2, 46 SBRMI_OUTBNDMSG3, 47 SBRMI_OUTBNDMSG4, 48 SBRMI_OUTBNDMSG5, 49 SBRMI_OUTBNDMSG6, 50 SBRMI_OUTBNDMSG7, 51 SBRMI_INBNDMSG0, 52 SBRMI_INBNDMSG1, 53 SBRMI_INBNDMSG2, 54 SBRMI_INBNDMSG3, 55 SBRMI_INBNDMSG4, 56 SBRMI_INBNDMSG5, 57 SBRMI_INBNDMSG6, 58 SBRMI_INBNDMSG7, 59 SBRMI_SW_INTERRUPT, 60 }; 61 62 /* Each client has this additional data */ 63 struct sbrmi_data { 64 struct i2c_client *client; 65 struct mutex lock; 66 u32 pwr_limit_max; 67 }; 68 69 struct sbrmi_mailbox_msg { 70 u8 cmd; 71 bool read; 72 u32 data_in; 73 u32 data_out; 74 }; 75 76 static int sbrmi_enable_alert(struct i2c_client *client) 77 { 78 int ctrl; 79 80 /* 81 * Enable the SB-RMI Software alert status 82 * by writing 0 to bit 4 of Control register(0x1) 83 */ 84 ctrl = i2c_smbus_read_byte_data(client, SBRMI_CTRL); 85 if (ctrl < 0) 86 return ctrl; 87 88 if (ctrl & 0x10) { 89 ctrl &= ~0x10; 90 return i2c_smbus_write_byte_data(client, 91 SBRMI_CTRL, ctrl); 92 } 93 94 return 0; 95 } 96 97 static int rmi_mailbox_xfer(struct sbrmi_data *data, 98 struct sbrmi_mailbox_msg *msg) 99 { 100 int i, ret, retry = 10; 101 int sw_status; 102 u8 byte; 103 104 mutex_lock(&data->lock); 105 106 /* Indicate firmware a command is to be serviced */ 107 ret = i2c_smbus_write_byte_data(data->client, 108 SBRMI_INBNDMSG7, START_CMD); 109 if (ret < 0) 110 goto exit_unlock; 111 112 /* Write the command to SBRMI::InBndMsg_inst0 */ 113 ret = i2c_smbus_write_byte_data(data->client, 114 SBRMI_INBNDMSG0, msg->cmd); 115 if (ret < 0) 116 goto exit_unlock; 117 118 /* 119 * For both read and write the initiator (BMC) writes 120 * Command Data In[31:0] to SBRMI::InBndMsg_inst[4:1] 121 * SBRMI_x3C(MSB):SBRMI_x39(LSB) 122 */ 123 for (i = 0; i < 4; i++) { 124 byte = (msg->data_in >> i * 8) & 0xff; 125 ret = i2c_smbus_write_byte_data(data->client, 126 SBRMI_INBNDMSG1 + i, byte); 127 if (ret < 0) 128 goto exit_unlock; 129 } 130 131 /* 132 * Write 0x01 to SBRMI::SoftwareInterrupt to notify firmware to 133 * perform the requested read or write command 134 */ 135 ret = i2c_smbus_write_byte_data(data->client, 136 SBRMI_SW_INTERRUPT, TRIGGER_MAILBOX); 137 if (ret < 0) 138 goto exit_unlock; 139 140 /* 141 * Firmware will write SBRMI::Status[SwAlertSts]=1 to generate 142 * an ALERT (if enabled) to initiator (BMC) to indicate completion 143 * of the requested command 144 */ 145 do { 146 sw_status = i2c_smbus_read_byte_data(data->client, 147 SBRMI_STATUS); 148 if (sw_status < 0) { 149 ret = sw_status; 150 goto exit_unlock; 151 } 152 if (sw_status & SW_ALERT_MASK) 153 break; 154 usleep_range(50, 100); 155 } while (retry--); 156 157 if (retry < 0) { 158 dev_err(&data->client->dev, 159 "Firmware fail to indicate command completion\n"); 160 ret = -EIO; 161 goto exit_unlock; 162 } 163 164 /* 165 * For a read operation, the initiator (BMC) reads the firmware 166 * response Command Data Out[31:0] from SBRMI::OutBndMsg_inst[4:1] 167 * {SBRMI_x34(MSB):SBRMI_x31(LSB)}. 168 */ 169 if (msg->read) { 170 for (i = 0; i < 4; i++) { 171 ret = i2c_smbus_read_byte_data(data->client, 172 SBRMI_OUTBNDMSG1 + i); 173 if (ret < 0) 174 goto exit_unlock; 175 msg->data_out |= ret << i * 8; 176 } 177 } 178 179 /* 180 * BMC must write 1'b1 to SBRMI::Status[SwAlertSts] to clear the 181 * ALERT to initiator 182 */ 183 ret = i2c_smbus_write_byte_data(data->client, SBRMI_STATUS, 184 sw_status | SW_ALERT_MASK); 185 186 exit_unlock: 187 mutex_unlock(&data->lock); 188 return ret; 189 } 190 191 static int sbrmi_read(struct device *dev, enum hwmon_sensor_types type, 192 u32 attr, int channel, long *val) 193 { 194 struct sbrmi_data *data = dev_get_drvdata(dev); 195 struct sbrmi_mailbox_msg msg = { 0 }; 196 int ret; 197 198 if (type != hwmon_power) 199 return -EINVAL; 200 201 msg.read = true; 202 switch (attr) { 203 case hwmon_power_input: 204 msg.cmd = SBRMI_READ_PKG_PWR_CONSUMPTION; 205 ret = rmi_mailbox_xfer(data, &msg); 206 break; 207 case hwmon_power_cap: 208 msg.cmd = SBRMI_READ_PKG_PWR_LIMIT; 209 ret = rmi_mailbox_xfer(data, &msg); 210 break; 211 case hwmon_power_cap_max: 212 msg.data_out = data->pwr_limit_max; 213 ret = 0; 214 break; 215 default: 216 return -EINVAL; 217 } 218 if (ret < 0) 219 return ret; 220 /* hwmon power attributes are in microWatt */ 221 *val = (long)msg.data_out * 1000; 222 return ret; 223 } 224 225 static int sbrmi_write(struct device *dev, enum hwmon_sensor_types type, 226 u32 attr, int channel, long val) 227 { 228 struct sbrmi_data *data = dev_get_drvdata(dev); 229 struct sbrmi_mailbox_msg msg = { 0 }; 230 231 if (type != hwmon_power && attr != hwmon_power_cap) 232 return -EINVAL; 233 /* 234 * hwmon power attributes are in microWatt 235 * mailbox read/write is in mWatt 236 */ 237 val /= 1000; 238 239 val = clamp_val(val, SBRMI_PWR_MIN, data->pwr_limit_max); 240 241 msg.cmd = SBRMI_WRITE_PKG_PWR_LIMIT; 242 msg.data_in = val; 243 msg.read = false; 244 245 return rmi_mailbox_xfer(data, &msg); 246 } 247 248 static umode_t sbrmi_is_visible(const void *data, 249 enum hwmon_sensor_types type, 250 u32 attr, int channel) 251 { 252 switch (type) { 253 case hwmon_power: 254 switch (attr) { 255 case hwmon_power_input: 256 case hwmon_power_cap_max: 257 return 0444; 258 case hwmon_power_cap: 259 return 0644; 260 } 261 break; 262 default: 263 break; 264 } 265 return 0; 266 } 267 268 static const struct hwmon_channel_info * const sbrmi_info[] = { 269 HWMON_CHANNEL_INFO(power, 270 HWMON_P_INPUT | HWMON_P_CAP | HWMON_P_CAP_MAX), 271 NULL 272 }; 273 274 static const struct hwmon_ops sbrmi_hwmon_ops = { 275 .is_visible = sbrmi_is_visible, 276 .read = sbrmi_read, 277 .write = sbrmi_write, 278 }; 279 280 static const struct hwmon_chip_info sbrmi_chip_info = { 281 .ops = &sbrmi_hwmon_ops, 282 .info = sbrmi_info, 283 }; 284 285 static int sbrmi_get_max_pwr_limit(struct sbrmi_data *data) 286 { 287 struct sbrmi_mailbox_msg msg = { 0 }; 288 int ret; 289 290 msg.cmd = SBRMI_READ_PKG_MAX_PWR_LIMIT; 291 msg.read = true; 292 ret = rmi_mailbox_xfer(data, &msg); 293 if (ret < 0) 294 return ret; 295 data->pwr_limit_max = msg.data_out; 296 297 return ret; 298 } 299 300 static int sbrmi_probe(struct i2c_client *client) 301 { 302 struct device *dev = &client->dev; 303 struct device *hwmon_dev; 304 struct sbrmi_data *data; 305 int ret; 306 307 data = devm_kzalloc(dev, sizeof(struct sbrmi_data), GFP_KERNEL); 308 if (!data) 309 return -ENOMEM; 310 311 data->client = client; 312 mutex_init(&data->lock); 313 314 /* Enable alert for SB-RMI sequence */ 315 ret = sbrmi_enable_alert(client); 316 if (ret < 0) 317 return ret; 318 319 /* Cache maximum power limit */ 320 ret = sbrmi_get_max_pwr_limit(data); 321 if (ret < 0) 322 return ret; 323 324 hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, data, 325 &sbrmi_chip_info, NULL); 326 327 return PTR_ERR_OR_ZERO(hwmon_dev); 328 } 329 330 static const struct i2c_device_id sbrmi_id[] = { 331 {"sbrmi", 0}, 332 {} 333 }; 334 MODULE_DEVICE_TABLE(i2c, sbrmi_id); 335 336 static const struct of_device_id __maybe_unused sbrmi_of_match[] = { 337 { 338 .compatible = "amd,sbrmi", 339 }, 340 { }, 341 }; 342 MODULE_DEVICE_TABLE(of, sbrmi_of_match); 343 344 static struct i2c_driver sbrmi_driver = { 345 .class = I2C_CLASS_HWMON, 346 .driver = { 347 .name = "sbrmi", 348 .of_match_table = of_match_ptr(sbrmi_of_match), 349 }, 350 .probe_new = sbrmi_probe, 351 .id_table = sbrmi_id, 352 }; 353 354 module_i2c_driver(sbrmi_driver); 355 356 MODULE_AUTHOR("Akshay Gupta <akshay.gupta@amd.com>"); 357 MODULE_DESCRIPTION("Hwmon driver for AMD SB-RMI emulated sensor"); 358 MODULE_LICENSE("GPL"); 359