Re: [PATCH v1 6/9] hwmon: Add Nuvoton NCT6694 HWMON support

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On 10/24/24 02:20, Kalesh Anakkur Purayil wrote:

On Thu, Oct 24, 2024 at 2:33 PM Ming Yu <a0282524688@xxxxxxxxx> wrote:


This driver supports Hardware monitor functionality for NCT6694 MFD
device based on USB interface.

Signed-off-by: Ming Yu <tmyu0@xxxxxxxxxxx>
---
  MAINTAINERS                   |   1 +
  drivers/hwmon/Kconfig         |  10 +
  drivers/hwmon/Makefile        |   1 +
  drivers/hwmon/nct6694-hwmon.c | 407 ++++++++++++++++++++++++++++++++++
  4 files changed, 419 insertions(+)
  create mode 100644 drivers/hwmon/nct6694-hwmon.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 63387c0d4ab6..2aa87ad84156 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -16439,6 +16439,7 @@ M:      Ming Yu <tmyu0@xxxxxxxxxxx>
  L:     linux-kernel@xxxxxxxxxxxxxxx
  S:     Supported
  F:     drivers/gpio/gpio-nct6694.c
+F:     drivers/hwmon/nct6694-hwmon.c
  F:     drivers/i2c/busses/i2c-nct6694.c
  F:     drivers/mfd/nct6694.c
  F:     drivers/net/can/nct6694_canfd.c
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 08a3c863f80a..740e4afe6582 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1625,6 +1625,16 @@ config SENSORS_NCT6683
           This driver can also be built as a module. If so, the module
           will be called nct6683.

+config SENSORS_NCT6694
+       tristate "Nuvoton NCT6694 Hardware Monitor support"
+       depends on MFD_NCT6694
+       help
+         Say Y here to support Nuvoton NCT6694 hardware monitoring
+         functionality.
+
+         This driver can also be built as a module. If so, the module
+         will be called nct6694-hwmon.
+
  config SENSORS_NCT6775_CORE
         tristate
         select REGMAP
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 9554d2fdcf7b..729961176d00 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -167,6 +167,7 @@ obj-$(CONFIG_SENSORS_MLXREG_FAN) += mlxreg-fan.o
  obj-$(CONFIG_SENSORS_MENF21BMC_HWMON) += menf21bmc_hwmon.o
  obj-$(CONFIG_SENSORS_MR75203)  += mr75203.o
  obj-$(CONFIG_SENSORS_NCT6683)  += nct6683.o
+obj-$(CONFIG_SENSORS_NCT6694)  += nct6694-hwmon.o
  obj-$(CONFIG_SENSORS_NCT6775_CORE) += nct6775-core.o
  nct6775-objs                   := nct6775-platform.o
  obj-$(CONFIG_SENSORS_NCT6775)  += nct6775.o
diff --git a/drivers/hwmon/nct6694-hwmon.c b/drivers/hwmon/nct6694-hwmon.c
new file mode 100644
index 000000000000..7d7d22a650b0
--- /dev/null
+++ b/drivers/hwmon/nct6694-hwmon.c
@@ -0,0 +1,407 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Nuvoton NCT6694 HWMON driver based on USB interface.
+ *
+ * Copyright (C) 2024 Nuvoton Technology Corp.
+ */
+
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/hwmon.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/nct6694.h>
+
+#define DRVNAME "nct6694-hwmon"
+
+/* Host interface */
+#define REQUEST_RPT_MOD                        0xFF
+#define REQUEST_HWMON_MOD              0x00
+
+/* Report Channel */
+#define HWMON_FIN_IDX(x)               (0x50 + ((x) * 2))
+#define HWMON_FIN_STS(x)               (0x6E + (x))
+#define HWMON_PWM_IDX(x)               (0x70 + (x))
+
+/* Message Channel*/
+/* Command 00h */
+#define REQUEST_HWMON_CMD0_LEN         0x40
+#define REQUEST_HWMON_CMD0_OFFSET      0x0000  /* OFFSET = SEL|CMD */
+#define HWMON_FIN_EN(x)                        (0x04 + (x))
+#define HWMON_PWM_FREQ_IDX(x)          (0x30 + (x))
+/* Command 02h */
+#define REQUEST_HWMON_CMD2_LEN         0x90
+#define REQUEST_HWMON_CMD2_OFFSET      0x0002  /* OFFSET = SEL|CMD */
+#define HWMON_SMI_CTRL_IDX             0x00
+#define HWMON_FIN_LIMIT_IDX(x)         (0x70 + ((x) * 2))
+#define HWMON_CMD2_HYST_MASK           0x1F
+/* Command 03h */
+#define REQUEST_HWMON_CMD3_LEN         0x08
+#define REQUEST_HWMON_CMD3_OFFSET      0x0003  /* OFFSET = SEL|CMD */
+
+struct nct6694_hwmon_data {
+       struct nct6694 *nct6694;
+
+       /* Make sure read & write commands are consecutive */
+       struct mutex hwmon_lock;
+};
+
+#define NCT6694_HWMON_FAN_CONFIG (HWMON_F_ENABLE | HWMON_F_INPUT | \
+                                 HWMON_F_MIN | HWMON_F_MIN_ALARM)
+#define NCT6694_HWMON_PWM_CONFIG (HWMON_PWM_INPUT | HWMON_PWM_FREQ)
+
+static const struct hwmon_channel_info *nct6694_info[] = {
+       HWMON_CHANNEL_INFO(fan,
+                          NCT6694_HWMON_FAN_CONFIG,    /* FIN0 */
+                          NCT6694_HWMON_FAN_CONFIG,    /* FIN1 */
+                          NCT6694_HWMON_FAN_CONFIG,    /* FIN2 */
+                          NCT6694_HWMON_FAN_CONFIG,    /* FIN3 */
+                          NCT6694_HWMON_FAN_CONFIG,    /* FIN4 */
+                          NCT6694_HWMON_FAN_CONFIG,    /* FIN5 */
+                          NCT6694_HWMON_FAN_CONFIG,    /* FIN6 */
+                          NCT6694_HWMON_FAN_CONFIG,    /* FIN7 */
+                          NCT6694_HWMON_FAN_CONFIG,    /* FIN8 */
+                          NCT6694_HWMON_FAN_CONFIG),   /* FIN9 */
+
+       HWMON_CHANNEL_INFO(pwm,
+                          NCT6694_HWMON_PWM_CONFIG,    /* PWM0 */
+                          NCT6694_HWMON_PWM_CONFIG,    /* PWM1 */
+                          NCT6694_HWMON_PWM_CONFIG,    /* PWM2 */
+                          NCT6694_HWMON_PWM_CONFIG,    /* PWM3 */
+                          NCT6694_HWMON_PWM_CONFIG,    /* PWM4 */
+                          NCT6694_HWMON_PWM_CONFIG,    /* PWM5 */
+                          NCT6694_HWMON_PWM_CONFIG,    /* PWM6 */
+                          NCT6694_HWMON_PWM_CONFIG,    /* PWM7 */
+                          NCT6694_HWMON_PWM_CONFIG,    /* PWM8 */
+                          NCT6694_HWMON_PWM_CONFIG),   /* PWM9 */
+       NULL
+};
+
+static int nct6694_fan_read(struct device *dev, u32 attr, int channel,
+                           long *val)
+{
+       struct nct6694_hwmon_data *data = dev_get_drvdata(dev);
+       unsigned char buf[2];
+       int ret;
+
+       switch (attr) {
+       case hwmon_fan_enable:
+               ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
+                                      REQUEST_HWMON_CMD0_OFFSET,
+                                      REQUEST_HWMON_CMD0_LEN,
+                                      HWMON_FIN_EN(channel / 8),
+                                      1, buf);
+               if (ret)
+                       return -EINVAL;
+
+               *val = buf[0] & BIT(channel % 8) ? 1 : 0;
+
+               break;
+
+       case hwmon_fan_input:
+               ret = nct6694_read_msg(data->nct6694, REQUEST_RPT_MOD,
+                                      HWMON_FIN_IDX(channel), 2, 0,
+                                      2, buf);
+               if (ret)
+                       return -EINVAL;
+
+               *val = (buf[1] | (buf[0] << 8)) & 0xFFFF;
+
+               break;
+
+       case hwmon_fan_min:
+               ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
+                                      REQUEST_HWMON_CMD2_OFFSET,
+                                      REQUEST_HWMON_CMD2_LEN,
+                                      HWMON_FIN_LIMIT_IDX(channel),
+                                      2, buf);
+               if (ret)
+                       return -EINVAL;
+
+               *val = (buf[1] | (buf[0] << 8)) & 0xFFFF;
+
+               break;
+
+       case hwmon_fan_min_alarm:
+               ret = nct6694_read_msg(data->nct6694, REQUEST_RPT_MOD,
+                                      HWMON_FIN_STS(channel / 8),
+                                      1, 0, 1, buf);
+               if (ret)
+                       return -EINVAL;
+
+               *val = buf[0] & BIT(channel % 8);
+
+               break;
+
+       default:
+               return -EOPNOTSUPP;
+       }
+
+       return 0;
+}
+
+static int nct6694_pwm_read(struct device *dev, u32 attr, int channel,
+                           long *val)
+{
+       struct nct6694_hwmon_data *data = dev_get_drvdata(dev);
+       unsigned char buf;
+       int ret;
+
+       switch (attr) {
+       case hwmon_pwm_input:
+               ret = nct6694_read_msg(data->nct6694, REQUEST_RPT_MOD,
+                                      HWMON_PWM_IDX(channel),
+                                      1, 0, 1, &buf);
+               if (ret)
+                       return -EINVAL;
+
+               *val = buf;
+
+               break;
+       case hwmon_pwm_freq:
+               ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
+                                      REQUEST_HWMON_CMD0_OFFSET,
+                                      REQUEST_HWMON_CMD0_LEN,
+                                      HWMON_PWM_FREQ_IDX(channel),
+                                      1, &buf);
+               if (ret)
+                       return -EINVAL;
+
+               *val = buf * 25000 / 255;
+
+               break;
+
+       default:
+               return -EOPNOTSUPP;
+       }
+
+       return 0;
+}
+
+static int nct6694_fan_write(struct device *dev, u32 attr, int channel,
+                            long val)
+{
+       struct nct6694_hwmon_data *data = dev_get_drvdata(dev);
+       unsigned char enable_buf[REQUEST_HWMON_CMD0_LEN] = {0};

[Kalesh] Please try to maintain RCT order for variable declaration


Ok, but that is already the case here ?


+       unsigned char buf[REQUEST_HWMON_CMD2_LEN] = {0};
+       u16 fan_val = (u16)val;
+       int ret;
+
+       switch (attr) {
+       case hwmon_fan_enable:
+               mutex_lock(&data->hwmon_lock);
+               ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
+                                      REQUEST_HWMON_CMD0_OFFSET,
+                                      REQUEST_HWMON_CMD0_LEN, 0,
+                                      REQUEST_HWMON_CMD0_LEN,
+                                      enable_buf);
+               if (ret)
+                       goto err;
+
+               if (val)
+                       enable_buf[HWMON_FIN_EN(channel / 8)] |= BIT(channel % 8);
+               else
+                       enable_buf[HWMON_FIN_EN(channel / 8)] &= ~BIT(channel % 8);
+
+               ret = nct6694_write_msg(data->nct6694, REQUEST_HWMON_MOD,
+                                       REQUEST_HWMON_CMD0_OFFSET,
+                                       REQUEST_HWMON_CMD0_LEN, enable_buf);
+               if (ret)
+                       goto err;
+
+               break;
+
+       case hwmon_fan_min:
+               mutex_lock(&data->hwmon_lock);
+               ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
+                                      REQUEST_HWMON_CMD2_OFFSET,
+                                      REQUEST_HWMON_CMD2_LEN, 0,
+                                      REQUEST_HWMON_CMD2_LEN, buf);
+               if (ret)
+                       goto err;
+
+               buf[HWMON_FIN_LIMIT_IDX(channel)] = (u8)((fan_val >> 8) & 0xFF);
+               buf[HWMON_FIN_LIMIT_IDX(channel) + 1] = (u8)(fan_val & 0xFF);
+               ret = nct6694_write_msg(data->nct6694, REQUEST_HWMON_MOD,
+                                       REQUEST_HWMON_CMD2_OFFSET,
+                                       REQUEST_HWMON_CMD2_LEN, buf);
+               if (ret)
+                       goto err;
+
+               break;
+
+       default:
+               ret = -EOPNOTSUPP;

[Kalesh] If you initialize "ret = -EOPNOTSUPP;" during declararion,
you can just break from here.


You are missing the point. The lock wasn't acquired here in the first place.
It is conceptually wrong to acquire a lock in the switch statement and release
it outside. This patch is a case in point.


+               goto err;
+       }
+
+err:
+       mutex_unlock(&data->hwmon_lock);
+       return ret;
+}
+
+static int nct6694_read(struct device *dev, enum hwmon_sensor_types type,
+                       u32 attr, int channel, long *val)
+{
+       switch (type) {
+       case hwmon_fan: /* in RPM */
+               return nct6694_fan_read(dev, attr, channel, val);
+
+       case hwmon_pwm: /* in value 0~255 */
+               return nct6694_pwm_read(dev, attr, channel, val);
+
+       default:
+               return -EOPNOTSUPP;
+       }
+
+       return 0;
+}
+
+static int nct6694_write(struct device *dev, enum hwmon_sensor_types type,
+                        u32 attr, int channel, long val)
+{
+       switch (type) {
+       case hwmon_fan:
+               return nct6694_fan_write(dev, attr, channel, val);
+       default:
+               return -EOPNOTSUPP;
+       }

[Kalesh] You can use simple if condition here than a switch like:
if (type != hwmon_fan)
          return -EOPNOTSUPP;
return nct6694_fan_write(dev, attr, channel, val);


That is a bit POV. I'd leave that to the developer.
More important is that the return statements after the switch are unnecessary
and never reached if each case returns immediately.


+
+       return 0;
+}
+
+static umode_t nct6694_is_visible(const void *data, enum hwmon_sensor_types type,
+                                 u32 attr, int channel)
+{
+       switch (type) {
+       case hwmon_fan:
+               switch (attr) {
+               case hwmon_fan_enable:
+               case hwmon_fan_min:
+                       return 0644;

[Kalesh] I think there is no need to leave a new line in between cases

+
+               case hwmon_fan_input:
+               case hwmon_fan_min_alarm:
+                       return 0444;
+
+               default:
+                       return 0;
+               }
+
+       case hwmon_pwm:
+               switch (attr) {
+               case hwmon_pwm_input:
+               case hwmon_pwm_freq:
+                       return 0444;
+               default:
+                       return 0;
+               }
+
+       default:
+               return 0;
+       }
+
+       return 0;

[Kalesh] This return statement looks redundant as the execution never
reaches here. Same comment applies to other functions above as well.

+}
+
+static const struct hwmon_ops nct6694_hwmon_ops = {
+       .is_visible = nct6694_is_visible,
+       .read = nct6694_read,
+       .write = nct6694_write,
+};
+
+static const struct hwmon_chip_info nct6694_chip_info = {
+       .ops = &nct6694_hwmon_ops,
+       .info = nct6694_info,
+};
+
+static int nct6694_hwmon_init(struct nct6694_hwmon_data *data)
+{
+       unsigned char buf[REQUEST_HWMON_CMD2_LEN] = {0};
+       int ret;
+
+       /* Set Fan input Real Time alarm mode */
+       mutex_lock(&data->hwmon_lock);
+       ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
+                              REQUEST_HWMON_CMD2_OFFSET,
+                              REQUEST_HWMON_CMD2_LEN, 0,
+                              REQUEST_HWMON_CMD2_LEN, buf);
+       if (ret)
+               goto err;

[Kalesh] It would be better to rename the label as "unlock". Same
comment on other functions as well.


The lock is not needed here in the first place. The function is called
exactly once during initialization.


+
+       buf[HWMON_SMI_CTRL_IDX] = 0x02;
+
+       ret = nct6694_write_msg(data->nct6694, REQUEST_HWMON_MOD,
+                               REQUEST_HWMON_CMD2_OFFSET,
+                               REQUEST_HWMON_CMD2_LEN, buf);
+       if (ret)
+               goto err;
+
+err:
+       mutex_unlock(&data->hwmon_lock);
+       return ret;
+}
+
+static int nct6694_hwmon_probe(struct platform_device *pdev)
+{
+       struct nct6694_hwmon_data *data;
+       struct nct6694 *nct6694 = dev_get_drvdata(pdev->dev.parent);
+       struct device *hwmon_dev;
+       int ret;
+
+       data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+       if (!data)
+               return -ENOMEM;
+
+       data->nct6694 = nct6694;
+       mutex_init(&data->hwmon_lock);
+       platform_set_drvdata(pdev, data);
+
+       ret = nct6694_hwmon_init(data);
+       if (ret)
+               return -EIO;
+
+       /* Register hwmon device to HWMON framework */
+       hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
+                                                        "nct6694", data,
+                                                        &nct6694_chip_info,
+                                                        NULL);
+       if (IS_ERR(hwmon_dev)) {
+               dev_err(&pdev->dev, "%s: Failed to register hwmon device!\n",
+                       __func__);
+               return PTR_ERR(hwmon_dev);
+       }
+
+       return 0;
+}
+
+static struct platform_driver nct6694_hwmon_driver = {
+       .driver = {
+               .name   = DRVNAME,
+       },
+       .probe          = nct6694_hwmon_probe,
+};
+
+static int __init nct6694_init(void)
+{
+       int err;
+
+       err = platform_driver_register(&nct6694_hwmon_driver);
+       if (!err) {
+               if (err)

[Kalesh] This whole check looks strange. You can simplify this function as:
return platform_driver_register(&nct6694_hwmon_driver);

+                       platform_driver_unregister(&nct6694_hwmon_driver);
+       }
+
+       return err;
+}
+subsys_initcall(nct6694_init);
+
+static void __exit nct6694_exit(void)
+{
+       platform_driver_unregister(&nct6694_hwmon_driver);
+}
+module_exit(nct6694_exit);
+
+MODULE_DESCRIPTION("USB-HWMON driver for NCT6694");
+MODULE_AUTHOR("Ming Yu <tmyu0@xxxxxxxxxxx>");
+MODULE_LICENSE("GPL");
--
2.34.1
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