Re: [PATCH v5 2/2] hwmon: (nct7802) Make temperature/voltage sensors configurable

Oskar Senft
2021-10-09T18:53:53Z

Changes since "PATCH v4 2/2" as requested in the review:
- Changed device tree node name from "signal" to "channel".
- Removed unrelated changes to replace literal values with #defines.
- Fixed formatting issues by running clang-format.
- Removed unneccessary check for reg >= 1 && reg <= 3.
- nct7802_get_channel_config is now returning an error value.
- nct7802_configure_channels now stops processing the device tree on
the first error.
- Simplified logic for LTD default configuration in nct7802_configure_channels.

On Sat, Oct 9, 2021 at 2:53 PM Oskar Senft <osk@google.com> wrote:
>
> This change allows LTD and RTD inputs to be configured via
> device tree bindings. If the DT bindings are not present or
> invalid, the input configuration is not modified and left at
> HW defaults.
>
> Signed-off-by: Oskar Senft <osk@google.com>
> ---
> drivers/hwmon/nct7802.c | 133 ++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 129 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/hwmon/nct7802.c b/drivers/hwmon/nct7802.c
> index 604af2f6103a..e28f8eaf9f0f 100644
> --- a/drivers/hwmon/nct7802.c
> +++ b/drivers/hwmon/nct7802.c
> @@ -51,6 +51,23 @@ static const u8 REG_VOLTAGE_LIMIT_MSB_SHIFT[2][5] = {
> #define REG_CHIP_ID 0xfe
> #define REG_VERSION_ID 0xff
>
> +/*
> + * Resistance temperature detector (RTD) modes according to 7.2.32 Mode
> + * Selection Register
> + */
> +#define RTD_MODE_CURRENT 0x1
> +#define RTD_MODE_THERMISTOR 0x2
> +#define RTD_MODE_VOLTAGE 0x3
> +
> +#define MODE_RTD_MASK 0x3
> +#define MODE_LTD_EN 0x40
> +
> +/*
> + * Bit offset for sensors modes in REG_MODE.
> + * Valid for index 0..2, indicating RTD1..3.
> + */
> +#define MODE_BIT_OFFSET_RTD(index) ((index) * 2)
> +
> /*
> * Data structures and manipulation thereof
> */
> @@ -1038,7 +1055,116 @@ static const struct regmap_config nct7802_regmap_config = {
> .volatile_reg = nct7802_regmap_is_volatile,
> };
>
> -static int nct7802_init_chip(struct nct7802_data *data)
> +static int nct7802_get_channel_config(struct device *dev,
> + struct device_node *node, u8 *mode_mask,
> + u8 *mode_val)
> +{
> + u32 reg;
> + const char *type_str, *md_str;
> + u8 md;
> +
> + if (!node->name || of_node_cmp(node->name, "channel"))
> + return 0;
> +
> + if (of_property_read_u32(node, "reg", &reg)) {
> + dev_err(dev, "Could not read reg value for '%s'\n",
> + node->full_name);
> + return -EINVAL;
> + }
> +
> + if (reg > 3) {
> + dev_err(dev, "Invalid reg (%u) in '%s'\n", reg,
> + node->full_name);
> + return -EINVAL;
> + }
> +
> + if (reg == 0) {
> + if (!of_device_is_available(node))
> + *mode_val &= ~MODE_LTD_EN;
> + else
> + *mode_val |= MODE_LTD_EN;
> + *mode_mask |= MODE_LTD_EN;
> + return 0;
> + }
> +
> + /* At this point we have reg >= 1 && reg <= 3 */
> +
> + if (!of_device_is_available(node)) {
> + *mode_val &= ~(MODE_RTD_MASK << MODE_BIT_OFFSET_RTD(reg - 1));
> + *mode_mask |= MODE_RTD_MASK << MODE_BIT_OFFSET_RTD(reg - 1);
> + return 0;
> + }
> +
> + if (of_property_read_string(node, "sensor-type", &type_str)) {
> + dev_err(dev, "No type for '%s'\n", node->full_name);
> + return -EINVAL;
> + }
> +
> + if (!strcmp(type_str, "voltage")) {
> + *mode_val |= (RTD_MODE_VOLTAGE & MODE_RTD_MASK)
> + << MODE_BIT_OFFSET_RTD(reg - 1);
> + *mode_mask |= MODE_RTD_MASK << MODE_BIT_OFFSET_RTD(reg - 1);
> + return 0;
> + }
> +
> + if (strcmp(type_str, "temperature")) {
> + dev_err(dev, "Invalid type '%s' for '%s'\n", type_str,
> + node->full_name);
> + return -EINVAL;
> + }
> +
> + if (reg == 3) {
> + /* RTD3 only supports thermistor mode */
> + md = RTD_MODE_THERMISTOR;
> + } else {
> + if (of_property_read_string(node, "temperature-mode",
> + &md_str)) {
> + dev_err(dev, "No mode for '%s'\n", node->full_name);
> + return -EINVAL;
> + }
> +
> + if (!strcmp(md_str, "thermal-diode"))
> + md = RTD_MODE_CURRENT;
> + else if (!strcmp(md_str, "thermistor"))
> + md = RTD_MODE_THERMISTOR;
> + else {
> + dev_err(dev, "Invalid mode '%s' for '%s'\n", md_str,
> + node->full_name);
> + return -EINVAL;
> + }
> + }
> +
> + *mode_val |= (md & MODE_RTD_MASK) << MODE_BIT_OFFSET_RTD(reg - 1);
> + *mode_mask |= MODE_RTD_MASK << MODE_BIT_OFFSET_RTD(reg - 1);
> +
> + return 0;
> +}
> +
> +static int nct7802_configure_channels(struct device *dev,
> + struct nct7802_data *data)
> +{
> + bool found_channel_config = false;
> + u8 mode_mask = 0, mode_val = 0;
> + struct device_node *node;
> + int err;
> +
> + /* Enable local temperature sensor by default */
> + mode_val |= MODE_LTD_EN;
> + mode_mask |= MODE_LTD_EN;
> +
> + if (dev->of_node) {
> + for_each_child_of_node(dev->of_node, node) {
> + err = nct7802_get_channel_config(dev, node, &mode_mask,
> + &mode_val);
> + if (err)
> + return err;
> + }
> + }
> +
> + return regmap_update_bits(data->regmap, REG_MODE, mode_mask, mode_val);
> +}
> +
> +static int nct7802_init_chip(struct device *dev, struct nct7802_data *data)
> {
> int err;
>
> @@ -1047,8 +1173,7 @@ static int nct7802_init_chip(struct nct7802_data *data)
> if (err)
> return err;
>
> - /* Enable local temperature sensor */
> - err = regmap_update_bits(data->regmap, REG_MODE, 0x40, 0x40);
> + err = nct7802_configure_channels(dev, data);
> if (err)
> return err;
>
> @@ -1074,7 +1199,7 @@ static int nct7802_probe(struct i2c_client *client)
> mutex_init(&data->access_lock);
> mutex_init(&data->in_alarm_lock);
>
> - ret = nct7802_init_chip(data);
> + ret = nct7802_init_chip(dev, data);
> if (ret < 0)
> return ret;
>
> --
> 2.33.0.882.g93a45727a2-goog
>