Re: [PATCH v4] hwmon: (max6650.c) Add devicetree support

Guenter Roeck
2016-08-19T04:07:09Z

On 08/16/2016 12:20 AM, Mike Looijmans wrote:
> Parse devicetree parameters for voltage and prescaler setting. This allows
> using multiple max6550 devices with varying settings, and also makes it
> possible to instantiate and configure the device using devicetree.
>
> Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
> ---
> v4: Vendor prefix "maxim," for devicetree properties and compatible string
> Split documentation into separate patch
> v3: Resubmit because wrong mailing lists used
> Fix style errors as reported by checkpatch.pl
> Fix bug in DT parsing of fan-prescale
> v2: Add devicetree binding documentation
> Code changes as suggested by Guenter
> Reduce log info, output only a single line
> drivers/hwmon/max6650.c | 47 ++++++++++++++++++++++++++++++++++++-----------
> 1 file changed, 36 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/hwmon/max6650.c b/drivers/hwmon/max6650.c
> index 162a520..6beb62c 100644
> --- a/drivers/hwmon/max6650.c
> +++ b/drivers/hwmon/max6650.c
> @@ -39,6 +39,7 @@
> #include <linux/hwmon.h>
> #include <linux/hwmon-sysfs.h>
> #include <linux/err.h>
> +#include <linux/of_device.h>
>
> /*
> * Insmod parameters
> @@ -48,7 +49,7 @@
> static int fan_voltage;
> /* prescaler: Possible values are 1, 2, 4, 8, 16 or 0 for don't change */
> static int prescaler;
> -/* clock: The clock frequency of the chip the driver should assume */
> +/* clock: The clock frequency of the chip (max6651 can be clocked externally) */
> static int clock = 254000;
>
> module_param(fan_voltage, int, S_IRUGO);
> @@ -133,6 +134,19 @@ static const u8 tach_reg[] = {
> MAX6650_REG_TACH3,
> };
>
> +static const struct of_device_id max6650_dt_match[] = {
> + {
> + .compatible = "maxim,max6650",
> + .data = (void *)1
> + },
> + {
> + .compatible = "maxim,max6651",
> + .data = (void *)4
> + },
> + { },
> +};
> +MODULE_DEVICE_TABLE(of, max6650_dt_match);
> +
> static struct max6650_data *max6650_update_device(struct device *dev)
> {
> struct max6650_data *data = dev_get_drvdata(dev);
> @@ -566,6 +580,17 @@ static int max6650_init_client(struct max6650_data *data,
> struct device *dev = &client->dev;
> int config;
> int err = -EIO;
> + u32 voltage;
> + u32 prescale;
> +
> + if (of_property_read_u32(dev->of_node, "maxim,fan-microvolt",
> + &voltage))
> + voltage = fan_voltage;
> + else
> + voltage = voltage > 5500000 ? 12 : 5;

I think this should only accept 5V or 12V.

Guenter

> + if (of_property_read_u32(dev->of_node, "maxim,fan-prescale",
> + &prescale))
> + prescale = prescaler;
>
> config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);
>
> @@ -574,7 +599,7 @@ static int max6650_init_client(struct max6650_data *data,
> return err;
> }
>
> - switch (fan_voltage) {
> + switch (voltage) {
> case 0:
> break;
> case 5:
> @@ -584,14 +609,10 @@ static int max6650_init_client(struct max6650_data *data,
> config |= MAX6650_CFG_V12;
> break;
> default:
> - dev_err(dev, "illegal value for fan_voltage (%d)\n",
> - fan_voltage);
> + dev_err(dev, "illegal value for fan_voltage (%d)\n", voltage);
> }
>
> - dev_info(dev, "Fan voltage is set to %dV.\n",
> - (config & MAX6650_CFG_V12) ? 12 : 5);
> -
> - switch (prescaler) {
> + switch (prescale) {
> case 0:
> break;
> case 1:
> @@ -614,10 +635,11 @@ static int max6650_init_client(struct max6650_data *data,
> | MAX6650_CFG_PRESCALER_16;
> break;
> default:
> - dev_err(dev, "illegal value for prescaler (%d)\n", prescaler);
> + dev_err(dev, "illegal value for prescaler (%d)\n", prescale);
> }
>
> - dev_info(dev, "Prescaler is set to %d.\n",
> + dev_info(dev, "Fan voltage: %dV, prescaler: %d.\n",
> + (config & MAX6650_CFG_V12) ? 12 : 5,
> 1 << (config & MAX6650_CFG_PRESCALER_MASK));
>
> /*
> @@ -651,6 +673,8 @@ static int max6650_probe(struct i2c_client *client,
> const struct i2c_device_id *id)
> {
> struct device *dev = &client->dev;
> + const struct of_device_id *of_id =
> + of_match_device(of_match_ptr(max6650_dt_match), dev);
> struct max6650_data *data;
> struct device *hwmon_dev;
> int err;
> @@ -661,7 +685,7 @@ static int max6650_probe(struct i2c_client *client,
>
> data->client = client;
> mutex_init(&data->update_lock);
> - data->nr_fans = id->driver_data;
> + data->nr_fans = of_id ? (int)(uintptr_t)of_id->data : id->driver_data;
>
> /*
> * Initialize the max6650 chip
> @@ -691,6 +715,7 @@ MODULE_DEVICE_TABLE(i2c, max6650_id);
> static struct i2c_driver max6650_driver = {
> .driver = {
> .name = "max6650",
> + .of_match_table = of_match_ptr(max6650_dt_match),
> },
> .probe = max6650_probe,
> .id_table = max6650_id,
>