Re: [PATCH v9 2/4] drivers: hwmon: sophgo: Add SG2042 external hardware monitor support
From: Guenter Roeck
Date: Fri Aug 02 2024 - 23:47:29 EST
On 8/2/24 16:28, Inochi Amaoto wrote:
On Fri, Aug 02, 2024 at 06:59:22AM GMT, Guenter Roeck wrote:
On 8/2/24 05:38, Inochi Amaoto wrote:
SG2042 use an external MCU to provide basic hardware information
and thermal sensors.
Add driver support for the onboard MCU of SG2042.
Signed-off-by: Inochi Amaoto <inochiama@xxxxxxxxxxx>
Tested-by: Chen Wang <unicorn_wang@xxxxxxxxxxx>
Reviewed-by: Chen Wang <unicorn_wang@xxxxxxxxxxx>
---
Documentation/hwmon/index.rst | 1 +
Documentation/hwmon/sg2042-mcu.rst | 39 +++
drivers/hwmon/Kconfig | 11 +
drivers/hwmon/Makefile | 1 +
drivers/hwmon/sg2042-mcu.c | 394 +++++++++++++++++++++++++++++
5 files changed, 446 insertions(+)
create mode 100644 Documentation/hwmon/sg2042-mcu.rst
create mode 100644 drivers/hwmon/sg2042-mcu.c
diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index 913c11390a45..ea3b5be8fe4f 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -206,6 +206,7 @@ Hardware Monitoring Kernel Drivers
sch5636
scpi-hwmon
sfctemp
+ sg2042-mcu
sht15
sht21
sht3x
diff --git a/Documentation/hwmon/sg2042-mcu.rst b/Documentation/hwmon/sg2042-mcu.rst
new file mode 100644
index 000000000000..250016b47dd1
--- /dev/null
+++ b/Documentation/hwmon/sg2042-mcu.rst
@@ -0,0 +1,39 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver sg2042-mcu
+=====================
+
+Supported chips:
+
+ * Onboard MCU for sg2042
+
+ Addresses scanned: -
+
+ Prefix: 'sg2042-mcu'
+
+Authors:
+
+ - Inochi Amaoto <inochiama@xxxxxxxxxxx>
+
+Description
+-----------
+
+This driver supprts hardware monitoring for onboard MCU with
+i2c interface.
+
+Usage Notes
+-----------
+
+This driver does not auto-detect devices. You will have to instantiate
+the devices explicitly.
+Please see Documentation/i2c/instantiating-devices.rst for details.
+
+Sysfs Attributes
+----------------
+
+================= =============================================
+temp1_input Measured temperature of SoC
+temp1_crit Critical high temperature
+temp1_crit_hyst hysteresis temperature restore from Critical
+temp2_input Measured temperature of the base board
+================= =============================================
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index b60fe2e58ad6..7aa6c3f322e5 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -2066,6 +2066,17 @@ config SENSORS_SFCTEMP
This driver can also be built as a module. If so, the module
will be called sfctemp.
+config SENSORS_SG2042_MCU
+ tristate "Sophgo onboard MCU support"
+ depends on I2C
+ depends on ARCH_SOPHGO || COMPILE_TEST
+ help
+ Support for onboard MCU of Sophgo SG2042 SoCs. This mcu provides
+ power control and some basic information.
+
+ This driver can be built as a module. If so, the module
+ will be called sg2042-mcu.
+
config SENSORS_SURFACE_FAN
tristate "Surface Fan Driver"
depends on SURFACE_AGGREGATOR
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index b1c7056c37db..0bbe812a67ae 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -194,6 +194,7 @@ obj-$(CONFIG_SENSORS_SCH56XX_COMMON)+= sch56xx-common.o
obj-$(CONFIG_SENSORS_SCH5627) += sch5627.o
obj-$(CONFIG_SENSORS_SCH5636) += sch5636.o
obj-$(CONFIG_SENSORS_SFCTEMP) += sfctemp.o
+obj-$(CONFIG_SENSORS_SG2042_MCU) += sg2042-mcu.o
obj-$(CONFIG_SENSORS_SL28CPLD) += sl28cpld-hwmon.o
obj-$(CONFIG_SENSORS_SHT15) += sht15.o
obj-$(CONFIG_SENSORS_SHT21) += sht21.o
diff --git a/drivers/hwmon/sg2042-mcu.c b/drivers/hwmon/sg2042-mcu.c
new file mode 100644
index 000000000000..6d8d677f86f3
--- /dev/null
+++ b/drivers/hwmon/sg2042-mcu.c
@@ -0,0 +1,394 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2024 Inochi Amaoto <inochiama@xxxxxxxxxxx>
+ *
+ * Sophgo power control mcu for SG2042
+ */
+
+#include <linux/cleanup.h>
+#include <linux/debugfs.h>
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+
+/* fixed MCU registers */
+#define REG_BOARD_TYPE 0x00
+#define REG_MCU_FIRMWARE_VERSION 0x01
+#define REG_PCB_VERSION 0x02
+#define REG_PWR_CTRL 0x03
+#define REG_SOC_TEMP 0x04
+#define REG_BOARD_TEMP 0x05
+#define REG_RST_COUNT 0x0a
+#define REG_UPTIME 0x0b
+#define REG_RESET_REASON 0x0d
+#define REG_MCU_TYPE 0x18
+#define REG_REPOWER_ACTION 0x65
+#define REG_CRITICAL_TEMP 0x66
+#define REG_REPOWER_TEMP 0x67
+
+#define REPOWER_ACTION_REBOOT 1
+#define REPOWER_ACTION_POWEROFF 2
+
+#define MCU_POWER_MAX 0xff
+
+#define DEFINE_MCU_DEBUG_ATTR(_name, _reg, _format) \
+ static int _name##_show(struct seq_file *seqf, \
+ void *unused) \
+ { \
+ struct sg2042_mcu_data *mcu = seqf->private; \
+ int ret; \
+ ret = i2c_smbus_read_byte_data(mcu->client, (_reg)); \
+ if (ret < 0) \
+ return ret; \
+ seq_printf(seqf, _format "\n", ret); \
+ return 0; \
+ } \
+ DEFINE_SHOW_ATTRIBUTE(_name) \
+
+struct sg2042_mcu_data {
+ struct i2c_client *client;
+ struct dentry *debugfs;
+ struct mutex mutex;
+};
+
+static struct dentry *sgmcu_debugfs;
+
+static ssize_t reset_count_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct sg2042_mcu_data *mcu = dev_get_drvdata(dev);
+ int ret;
+
+ ret = i2c_smbus_read_byte_data(mcu->client, REG_RST_COUNT);
+ if (ret < 0)
+ return ret;
+
+ return sprintf(buf, "%d\n", ret);
+}
+
+static ssize_t uptime_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct sg2042_mcu_data *mcu = dev_get_drvdata(dev);
+ u8 time_val[2];
+ int ret;
+
+ ret = i2c_smbus_read_i2c_block_data(mcu->client, REG_UPTIME,
+ sizeof(time_val), time_val);
+ if (ret < 0)
+ return ret;
+
+ return sprintf(buf, "%d\n",
+ (int)(time_val[0]) + (int)(time_val[1] << 8));
Pointless type casts
+}
+
+static ssize_t reset_reason_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct sg2042_mcu_data *mcu = dev_get_drvdata(dev);
+ int ret;
+
+ ret = i2c_smbus_read_byte_data(mcu->client, REG_RESET_REASON);
+ if (ret < 0)
+ return ret;
+
+ return sprintf(buf, "0x%02x\n", ret);
+}
+
+static ssize_t repower_action_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct sg2042_mcu_data *mcu = dev_get_drvdata(dev);
+ int ret;
+ const char *action;
+
+ ret = i2c_smbus_read_byte_data(mcu->client, REG_REPOWER_ACTION);
+ if (ret < 0)
+ return ret;
+
+ if (ret == REPOWER_ACTION_REBOOT)
+ action = "reboot";
+ else if (ret == REPOWER_ACTION_POWEROFF)
+ action = "poweroff";
+ else
+ action = "unknown";
+
+ return sprintf(buf, "%s\n", action);
+}
+
+static ssize_t repower_action_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct sg2042_mcu_data *mcu = dev_get_drvdata(dev);
+ u8 value;
+ int ret;
+
+ if (sysfs_streq("reboot", buf))
+ value = REPOWER_ACTION_REBOOT;
+ else if (sysfs_streq("poweroff", buf))
+ value = REPOWER_ACTION_POWEROFF;
+ else
+ return -EINVAL;
+
+ guard(mutex)(&mcu->mutex);
+
Pointless mutex protection.
OK, I have seen the protection in the i2c bus. I will remove this.
+ ret = i2c_smbus_write_byte_data(mcu->client,
+ REG_REPOWER_ACTION, value);
+ if (ret < 0)
+ return ret;
+
+ return count;
+}
+
+static DEVICE_ATTR_RO(reset_count);
+static DEVICE_ATTR_RO(uptime);
+static DEVICE_ATTR_RO(reset_reason);
+static DEVICE_ATTR_RW(repower_action);
+
+DEFINE_MCU_DEBUG_ATTR(firmware_version, REG_MCU_FIRMWARE_VERSION, "0x%02x");
+DEFINE_MCU_DEBUG_ATTR(pcb_version, REG_PCB_VERSION, "0x%02x");
+DEFINE_MCU_DEBUG_ATTR(board_type, REG_BOARD_TYPE, "0x%02x");
+DEFINE_MCU_DEBUG_ATTR(mcu_type, REG_MCU_TYPE, "%d");
+
+static struct attribute *sg2042_mcu_attrs[] = {
+ &dev_attr_reset_count.attr,
+ &dev_attr_uptime.attr,
+ &dev_attr_reset_reason.attr,
+ &dev_attr_repower_action.attr,
+ NULL
+};
+
+static const struct attribute_group sg2042_mcu_attr_group = {
+ .attrs = sg2042_mcu_attrs,
+};
+
+static const struct attribute_group *sg2042_mcu_groups[] = {
+ &sg2042_mcu_attr_group,
+ NULL
+};
+
+static const struct hwmon_channel_info * const sg2042_mcu_info[] = {
+ HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
+ HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_CRIT |
+ HWMON_T_CRIT_HYST,
+ HWMON_T_INPUT),
+ NULL
+};
+
+static int sg2042_mcu_read(struct device *dev,
+ enum hwmon_sensor_types type,
+ u32 attr, int channel, long *val)
+{
+ struct sg2042_mcu_data *mcu = dev_get_drvdata(dev);
+ int tmp;
+ u8 reg;
+
+ switch (attr) {
+ case hwmon_temp_input:
+ reg = channel ? REG_BOARD_TEMP : REG_SOC_TEMP;
+ break;
+ case hwmon_temp_crit:
+ reg = REG_CRITICAL_TEMP;
+ break;
+ case hwmon_temp_crit_hyst:
+ reg = REG_REPOWER_TEMP;
+ break;
+ default:
+ return -EOPNOTSUPP;
+ }
+
+ tmp = i2c_smbus_read_byte_data(mcu->client, reg);
+ if (tmp < 0)
+ return tmp;
+ *val = tmp * 1000;
+
+ return 0;
+}
+
+static int sg2042_mcu_write(struct device *dev,
+ enum hwmon_sensor_types type,
+ u32 attr, int channel, long val)
+{
+ struct sg2042_mcu_data *mcu = dev_get_drvdata(dev);
+ int temp = val / 1000;
+ int hyst_temp, crit_temp;
+ u8 reg;
+
+ if (temp > MCU_POWER_MAX)
+ temp = MCU_POWER_MAX;
+ else if (temp < 0)
+ temp = 0;
+
temp = clamp_val(temp, 0, MCU_POWER_MAX);
+ guard(mutex)(&mcu->mutex);
+
+ switch (attr) {
+ case hwmon_temp_crit:
+ hyst_temp = i2c_smbus_read_byte_data(mcu->client,
+ REG_REPOWER_TEMP);
+ if (hyst_temp < 0)
+ return hyst_temp;
+
+ crit_temp = temp;
+ reg = REG_CRITICAL_TEMP;
+ break;
+ case hwmon_temp_crit_hyst:
+ crit_temp = i2c_smbus_read_byte_data(mcu->client,
+ REG_CRITICAL_TEMP);
+ if (crit_temp < 0)
+ return crit_temp;
+
+ hyst_temp = temp;
+ reg = REG_REPOWER_TEMP;
+ break;
+ default:
+ return -EOPNOTSUPP;
+ }
+
+ /*
+ * ensure hyst_temp is smaller to avoid MCU from
+ * keeping triggering repower event.
+ */
+ if (crit_temp < hyst_temp)
+ return -EINVAL;
+
+ return i2c_smbus_write_byte_data(mcu->client, reg, temp);
+}
+
+static umode_t sg2042_mcu_is_visible(const void *_data,
+ enum hwmon_sensor_types type,
+ u32 attr, int channel)
+{
+ switch (type) {
+ case hwmon_temp:
+ switch (attr) {
+ case hwmon_temp_input:
+ return 0444;
+ case hwmon_temp_crit:
+ case hwmon_temp_crit_hyst:
+ if (channel == 0)
+ return 0664;
+ break;
In practice this is the only break; in this nested switch sequence,
making the return 0; at the end necessary.
Please either use break; always when returning 0, or return 0 here
as well and drop the final return 0;
Thanks, but I have a question: as this break can be fallthrough to the
default, is it better to use break;/return 0;, or just remove this
break; and let it fallthrough?
Either always use break; when returning 0 or always use "return 0;".
Please don't rely on fallthrough; it doesn't improve anything since you'd
have to tag it as fallthrough and you might then as well use break;
or return 0; directly.
Guenter
+ default:
+ return 0;
+ }
+ break;
+ default:
+ return 0;
+ }
+ return 0;
+}
+
+static const struct hwmon_ops sg2042_mcu_ops = {
+ .is_visible = sg2042_mcu_is_visible,
+ .read = sg2042_mcu_read,
+ .write = sg2042_mcu_write,
+};
+
+static const struct hwmon_chip_info sg2042_mcu_chip_info = {
+ .ops = &sg2042_mcu_ops,
+ .info = sg2042_mcu_info,
+};
+
+static void sg2042_mcu_debugfs_init(struct sg2042_mcu_data *mcu,
+ struct device *dev)
+{
+ mcu->debugfs = debugfs_create_dir(dev_name(dev), sgmcu_debugfs);
+ if (mcu->debugfs) {
debugfs_create_dir() returns an ERR_PTR(), which is checked in debugfs_create_file().
This if() is pointless.
Thanks.
+ debugfs_create_file("firmware_version", 0444, mcu->debugfs,
+ mcu, &firmware_version_fops);
+ debugfs_create_file("pcb_version", 0444, mcu->debugfs, mcu,
+ &pcb_version_fops);
+ debugfs_create_file("mcu_type", 0444, mcu->debugfs, mcu,
+ &mcu_type_fops);
+ debugfs_create_file("board_type", 0444, mcu->debugfs, mcu,
+ &board_type_fops);
+ }
+}
+
+static int sg2042_mcu_i2c_probe(struct i2c_client *client)
+{
+ struct device *dev = &client->dev;
+ struct sg2042_mcu_data *mcu;
+ struct device *hwmon_dev;
+
+ if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA |
+ I2C_FUNC_SMBUS_BLOCK_DATA))
+ return -EIO;
+
return -ENODEV;
+ mcu = devm_kmalloc(dev, sizeof(*mcu), GFP_KERNEL);
+ if (!mcu)
+ return -ENOMEM;
+
+ mutex_init(&mcu->mutex);
+ mcu->client = client;
+
+ i2c_set_clientdata(client, mcu);
+
+ hwmon_dev = devm_hwmon_device_register_with_info(dev, "sg2042_mcu",
+ mcu,
+ &sg2042_mcu_chip_info,
+ NULL);
+ if (IS_ERR_OR_NULL(hwmon_dev))
+ return -EFAULT;
devm_hwmon_device_register_with_info() returns an ERR_PTR(), and
returning -EFAULT instead of it is more than wrong (this does not indicate
a "bad address"). This needs to be
if (IS_ERR(hwmon_dev))
return PTR_ERR(hwmon_dev);
I am sure I asked before not to overwrite error codes.
Yes, you have asked, it seems that I have missed this code when I
check the driver. I apology for this mistake and thanks for your
reminder.
+
+ sg2042_mcu_debugfs_init(mcu, dev);
+
+ return 0;
+}
+
+static void sg2042_mcu_i2c_remove(struct i2c_client *client)
+{
+ struct sg2042_mcu_data *mcu = i2c_get_clientdata(client);
+
+ debugfs_remove_recursive(mcu->debugfs);
+}
+
+static const struct i2c_device_id sg2042_mcu_id[] = {
+ { "sg2042-hwmon-mcu", 0 },
+ {},
+};
+MODULE_DEVICE_TABLE(i2c, sg2042_mcu_id);
+
+static const struct of_device_id sg2042_mcu_of_id[] = {
+ { .compatible = "sophgo,sg2042-hwmon-mcu" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, sg2042_mcu_of_id);
+
+static struct i2c_driver sg2042_mcu_driver = {
+ .driver = {
+ .name = "sg2042-mcu",
+ .of_match_table = sg2042_mcu_of_id,
+ .dev_groups = sg2042_mcu_groups,
+ },
+ .probe = sg2042_mcu_i2c_probe,
+ .remove = sg2042_mcu_i2c_remove,
+ .id_table = sg2042_mcu_id,
+};
+
+static int __init sg2042_mcu_init(void)
+{
+ sgmcu_debugfs = debugfs_create_dir("sg2042-mcu", NULL);
+ return i2c_add_driver(&sg2042_mcu_driver);
+}
+
+static void __exit sg2042_mcu_exit(void)
+{
+ debugfs_remove_recursive(sgmcu_debugfs);
+ i2c_del_driver(&sg2042_mcu_driver);
+}
+
+module_init(sg2042_mcu_init);
+module_exit(sg2042_mcu_exit);
+
+MODULE_AUTHOR("Inochi Amaoto <inochiama@xxxxxxxxxxx>");
+MODULE_DESCRIPTION("MCU I2C driver for SG2042 soc platform");
+MODULE_LICENSE("GPL");