| Message ID | 20220428012707.24921-3-zev@bewilderbeest.net (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | hwmon: (nct6775) Add i2c driver | expand |
On Wed, Apr 27, 2022 at 06:27:07PM -0700, Zev Weiss wrote: > This driver provides an i2c I/O mechanism for the core nct6775 driver, > as might be used by a BMC. Because the Super I/O chip is shared with > the host CPU in such a scenario (and the host should ultimately be in > control of it), the i2c driver is strictly read-only to avoid > interfering with any usage by the host (aside from the bank-select > register, which seems to be replicated for the i2c interface). > > Signed-off-by: Zev Weiss <zev@bewilderbeest.net> > Tested-by: Renze Nicolai <renze@rnplus.nl> Applied. Thanks, Guenter > --- > MAINTAINERS | 7 ++ > drivers/hwmon/Kconfig | 17 ++++ > drivers/hwmon/Makefile | 1 + > drivers/hwmon/nct6775-i2c.c | 195 ++++++++++++++++++++++++++++++++++++ > 4 files changed, 220 insertions(+) > create mode 100644 drivers/hwmon/nct6775-i2c.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index 88fdb7cb3197..aac1a184a4c9 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -13538,6 +13538,13 @@ F: drivers/hwmon/nct6775-core.c > F: drivers/hwmon/nct6775-platform.c > F: drivers/hwmon/nct6775.h > > +NCT6775 HARDWARE MONITOR DRIVER - I2C DRIVER > +M: Zev Weiss <zev@bewilderbeest.net> > +L: linux-hwmon@vger.kernel.org > +S: Maintained > +F: Documentation/devicetree/bindings/hwmon/nuvoton,nct6775.yaml > +F: drivers/hwmon/nct6775-i2c.c > + > NETDEVSIM > M: Jakub Kicinski <kuba@kernel.org> > S: Maintained > diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig > index 85c22bba439b..a1dac1aa4e3a 100644 > --- a/drivers/hwmon/Kconfig > +++ b/drivers/hwmon/Kconfig > @@ -1489,6 +1489,23 @@ config SENSORS_NCT6775 > This driver can also be built as a module. If so, the module > will be called nct6775. > > +config SENSORS_NCT6775_I2C > + tristate "I2C driver for Nuvoton NCT6775F and compatibles" > + depends on I2C > + select REGMAP_I2C > + select SENSORS_NCT6775 > + help > + If you say yes here you get support for the hardware monitoring > + functionality of the Nuvoton NCT6106D, NCT6775F, NCT6776F, NCT6779D, > + NCT6791D, NCT6792D, NCT6793D, NCT6795D, NCT6796D, and compatible > + Super-I/O chips via their I2C interface. > + > + If you're not building a kernel for a BMC, this is probably > + not the driver you want (see CONFIG_SENSORS_NCT6775_PLATFORM). > + > + This driver can also be built as a module. If so, the module > + will be called nct6775-i2c. > + > config SENSORS_NCT7802 > tristate "Nuvoton NCT7802Y" > depends on I2C > diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile > index 93f2b774cc5e..004ab87c9b80 100644 > --- a/drivers/hwmon/Makefile > +++ b/drivers/hwmon/Makefile > @@ -157,6 +157,7 @@ obj-$(CONFIG_SENSORS_NCT6683) += nct6683.o > obj-$(CONFIG_SENSORS_NCT6775_CORE) += nct6775-core.o > nct6775-objs := nct6775-platform.o > obj-$(CONFIG_SENSORS_NCT6775) += nct6775.o > +obj-$(CONFIG_SENSORS_NCT6775_I2C) += nct6775-i2c.o > obj-$(CONFIG_SENSORS_NCT7802) += nct7802.o > obj-$(CONFIG_SENSORS_NCT7904) += nct7904.o > obj-$(CONFIG_SENSORS_NPCM7XX) += npcm750-pwm-fan.o > diff --git a/drivers/hwmon/nct6775-i2c.c b/drivers/hwmon/nct6775-i2c.c > new file mode 100644 > index 000000000000..e1bcd1146191 > --- /dev/null > +++ b/drivers/hwmon/nct6775-i2c.c > @@ -0,0 +1,195 @@ > +// 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_device.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, }, > + { }, > +}; > +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 }, > + { } > +}; > +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; > + const struct of_device_id *of_id; > + const struct i2c_device_id *i2c_id; > + struct device *dev = &client->dev; > + > + of_id = of_match_device(nct6775_i2c_of_match, dev); > + i2c_id = i2c_match_id(nct6775_i2c_id, client); > + > + if (of_id && (unsigned long)of_id->data != i2c_id->driver_data) > + dev_notice(dev, "Device mismatch: %s in device tree, %s detected\n", > + of_id->name, i2c_id->name); > + > + data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL); > + if (!data) > + return -ENOMEM; > + > + data->kind = i2c_id->driver_data; > + > + 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_new = 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);
diff --git a/MAINTAINERS b/MAINTAINERS index 88fdb7cb3197..aac1a184a4c9 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -13538,6 +13538,13 @@ F: drivers/hwmon/nct6775-core.c F: drivers/hwmon/nct6775-platform.c F: drivers/hwmon/nct6775.h +NCT6775 HARDWARE MONITOR DRIVER - I2C DRIVER +M: Zev Weiss <zev@bewilderbeest.net> +L: linux-hwmon@vger.kernel.org +S: Maintained +F: Documentation/devicetree/bindings/hwmon/nuvoton,nct6775.yaml +F: drivers/hwmon/nct6775-i2c.c + NETDEVSIM M: Jakub Kicinski <kuba@kernel.org> S: Maintained diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig index 85c22bba439b..a1dac1aa4e3a 100644 --- a/drivers/hwmon/Kconfig +++ b/drivers/hwmon/Kconfig @@ -1489,6 +1489,23 @@ config SENSORS_NCT6775 This driver can also be built as a module. If so, the module will be called nct6775. +config SENSORS_NCT6775_I2C + tristate "I2C driver for Nuvoton NCT6775F and compatibles" + depends on I2C + select REGMAP_I2C + select SENSORS_NCT6775 + help + If you say yes here you get support for the hardware monitoring + functionality of the Nuvoton NCT6106D, NCT6775F, NCT6776F, NCT6779D, + NCT6791D, NCT6792D, NCT6793D, NCT6795D, NCT6796D, and compatible + Super-I/O chips via their I2C interface. + + If you're not building a kernel for a BMC, this is probably + not the driver you want (see CONFIG_SENSORS_NCT6775_PLATFORM). + + This driver can also be built as a module. If so, the module + will be called nct6775-i2c. + config SENSORS_NCT7802 tristate "Nuvoton NCT7802Y" depends on I2C diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile index 93f2b774cc5e..004ab87c9b80 100644 --- a/drivers/hwmon/Makefile +++ b/drivers/hwmon/Makefile @@ -157,6 +157,7 @@ obj-$(CONFIG_SENSORS_NCT6683) += nct6683.o obj-$(CONFIG_SENSORS_NCT6775_CORE) += nct6775-core.o nct6775-objs := nct6775-platform.o obj-$(CONFIG_SENSORS_NCT6775) += nct6775.o +obj-$(CONFIG_SENSORS_NCT6775_I2C) += nct6775-i2c.o obj-$(CONFIG_SENSORS_NCT7802) += nct7802.o obj-$(CONFIG_SENSORS_NCT7904) += nct7904.o obj-$(CONFIG_SENSORS_NPCM7XX) += npcm750-pwm-fan.o diff --git a/drivers/hwmon/nct6775-i2c.c b/drivers/hwmon/nct6775-i2c.c new file mode 100644 index 000000000000..e1bcd1146191 --- /dev/null +++ b/drivers/hwmon/nct6775-i2c.c @@ -0,0 +1,195 @@ +// 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_device.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, }, + { }, +}; +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 }, + { } +}; +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; + const struct of_device_id *of_id; + const struct i2c_device_id *i2c_id; + struct device *dev = &client->dev; + + of_id = of_match_device(nct6775_i2c_of_match, dev); + i2c_id = i2c_match_id(nct6775_i2c_id, client); + + if (of_id && (unsigned long)of_id->data != i2c_id->driver_data) + dev_notice(dev, "Device mismatch: %s in device tree, %s detected\n", + of_id->name, i2c_id->name); + + data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + data->kind = i2c_id->driver_data; + + 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_new = 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);