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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 | // SPDX-License-Identifier: GPL-2.0 /* * nct6775-i2c - I2C driver for the hardware monitoring functionality of * Nuvoton NCT677x Super-I/O chips * * Copyright (C) 2022 Zev Weiss <zev@bewilderbeest.net> * * This driver interacts with the chip via it's "back door" i2c interface, as * is often exposed to a BMC. Because the host may still be operating the * chip via the ("front door") LPC interface, this driver cannot assume that * it actually has full control of the chip, and in particular must avoid * making any changes that could confuse the host's LPC usage of it. It thus * operates in a strictly read-only fashion, with the only exception being the * bank-select register (which seems, thankfully, to be replicated for the i2c * interface so it doesn't affect the LPC interface). */ #include <linux/module.h> #include <linux/init.h> #include <linux/i2c.h> #include <linux/hwmon.h> #include <linux/hwmon-sysfs.h> #include <linux/err.h> #include <linux/of.h> #include <linux/regmap.h> #include "nct6775.h" static int nct6775_i2c_read(void *ctx, unsigned int reg, unsigned int *val) { int ret; u32 tmp; u8 bank = reg >> 8; struct nct6775_data *data = ctx; struct i2c_client *client = data->driver_data; if (bank != data->bank) { ret = i2c_smbus_write_byte_data(client, NCT6775_REG_BANK, bank); if (ret) return ret; data->bank = bank; } ret = i2c_smbus_read_byte_data(client, reg & 0xff); if (ret < 0) return ret; tmp = ret; if (nct6775_reg_is_word_sized(data, reg)) { ret = i2c_smbus_read_byte_data(client, (reg & 0xff) + 1); if (ret < 0) return ret; tmp = (tmp << 8) | ret; } *val = tmp; return 0; } /* * The write operation is a dummy so as not to disturb anything being done * with the chip via LPC. */ static int nct6775_i2c_write(void *ctx, unsigned int reg, unsigned int value) { struct nct6775_data *data = ctx; struct i2c_client *client = data->driver_data; dev_dbg(&client->dev, "skipping attempted write: %02x -> %03x\n", value, reg); /* * This is a lie, but writing anything but the bank-select register is * something this driver shouldn't be doing. */ return 0; } static const struct of_device_id __maybe_unused nct6775_i2c_of_match[] = { { .compatible = "nuvoton,nct6106", .data = (void *)nct6106, }, { .compatible = "nuvoton,nct6116", .data = (void *)nct6116, }, { .compatible = "nuvoton,nct6775", .data = (void *)nct6775, }, { .compatible = "nuvoton,nct6776", .data = (void *)nct6776, }, { .compatible = "nuvoton,nct6779", .data = (void *)nct6779, }, { .compatible = "nuvoton,nct6791", .data = (void *)nct6791, }, { .compatible = "nuvoton,nct6792", .data = (void *)nct6792, }, { .compatible = "nuvoton,nct6793", .data = (void *)nct6793, }, { .compatible = "nuvoton,nct6795", .data = (void *)nct6795, }, { .compatible = "nuvoton,nct6796", .data = (void *)nct6796, }, { .compatible = "nuvoton,nct6797", .data = (void *)nct6797, }, { .compatible = "nuvoton,nct6798", .data = (void *)nct6798, }, { .compatible = "nuvoton,nct6799", .data = (void *)nct6799, }, { }, }; MODULE_DEVICE_TABLE(of, nct6775_i2c_of_match); static const struct i2c_device_id nct6775_i2c_id[] = { { "nct6106", nct6106 }, { "nct6116", nct6116 }, { "nct6775", nct6775 }, { "nct6776", nct6776 }, { "nct6779", nct6779 }, { "nct6791", nct6791 }, { "nct6792", nct6792 }, { "nct6793", nct6793 }, { "nct6795", nct6795 }, { "nct6796", nct6796 }, { "nct6797", nct6797 }, { "nct6798", nct6798 }, { "nct6799", nct6799 }, { } }; MODULE_DEVICE_TABLE(i2c, nct6775_i2c_id); static int nct6775_i2c_probe_init(struct nct6775_data *data) { u32 tsi_channel_mask; struct i2c_client *client = data->driver_data; /* * The i2c interface doesn't provide access to the control registers * needed to determine the presence of other fans, but fans 1 and 2 * are (in principle) always there. * * In practice this is perhaps a little silly, because the system * using this driver is mostly likely a BMC, and hence probably has * totally separate fan tachs & pwms of its own that are actually * controlling/monitoring the fans -- these are thus unlikely to be * doing anything actually useful. */ data->has_fan = 0x03; data->has_fan_min = 0x03; data->has_pwm = 0x03; /* * Because on a BMC this driver may be bound very shortly after power * is first applied to the device, the automatic TSI channel detection * in nct6775_probe() (which has already been run at this point) may * not find anything if a channel hasn't yet produced a temperature * reading. Augment whatever was found via autodetection (if * anything) with the channels DT says should be active. */ if (!of_property_read_u32(client->dev.of_node, "nuvoton,tsi-channel-mask", &tsi_channel_mask)) data->have_tsi_temp |= tsi_channel_mask & GENMASK(NUM_TSI_TEMP - 1, 0); return 0; } static const struct regmap_config nct6775_i2c_regmap_config = { .reg_bits = 16, .val_bits = 16, .reg_read = nct6775_i2c_read, .reg_write = nct6775_i2c_write, }; static int nct6775_i2c_probe(struct i2c_client *client) { struct nct6775_data *data; struct device *dev = &client->dev; data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL); if (!data) return -ENOMEM; data->kind = (enum kinds)(uintptr_t)i2c_get_match_data(client); data->read_only = true; data->driver_data = client; data->driver_init = nct6775_i2c_probe_init; return nct6775_probe(dev, data, &nct6775_i2c_regmap_config); } static struct i2c_driver nct6775_i2c_driver = { .class = I2C_CLASS_HWMON, .driver = { .name = "nct6775-i2c", .of_match_table = of_match_ptr(nct6775_i2c_of_match), }, .probe = nct6775_i2c_probe, .id_table = nct6775_i2c_id, }; module_i2c_driver(nct6775_i2c_driver); MODULE_AUTHOR("Zev Weiss <zev@bewilderbeest.net>"); MODULE_DESCRIPTION("I2C driver for NCT6775F and compatible chips"); MODULE_LICENSE("GPL"); MODULE_IMPORT_NS(HWMON_NCT6775); |