netdev - Re: [PATCH net-next] net: phy: mxl-gpy: add temperature sensor

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Date:   Wed, 22 Jun 2022 08:05:37 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Michael Walle <michael@...le.cc>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, Xu Liang <lxu@...linear.com>,
        Jean Delvare <jdelvare@...e.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org
Subject: Re: [PATCH net-next] net: phy: mxl-gpy: add temperature sensor

On Wed, Jun 22, 2022 at 04:17:16PM +0200, Michael Walle wrote:
> The GPY115 and GPY2xx PHYs contain an integrated temperature sensor. It
> accuracy is +/- 5°C. Add support for it.
> 
> Signed-off-by: Michael Walle <michael@...le.cc>

Acked-by: Guenter Roeck <linux@...ck-us.net>

> ---
>  drivers/net/phy/Kconfig   |   2 +
>  drivers/net/phy/mxl-gpy.c | 106 ++++++++++++++++++++++++++++++++++++++
>  2 files changed, 108 insertions(+)
> 
> diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
> index 9fee639ee5c8..09fa17796d4d 100644
> --- a/drivers/net/phy/Kconfig
> +++ b/drivers/net/phy/Kconfig
> @@ -216,6 +216,8 @@ config MARVELL_88X2222_PHY
>  
>  config MAXLINEAR_GPHY
>  	tristate "Maxlinear Ethernet PHYs"
> +	select POLYNOMIAL if HWMON
> +	depends on HWMON || HWMON=n
>  	help
>  	  Support for the Maxlinear GPY115, GPY211, GPY212, GPY215,
>  	  GPY241, GPY245 PHYs.
> diff --git a/drivers/net/phy/mxl-gpy.c b/drivers/net/phy/mxl-gpy.c
> index 6c4da2f9e90a..5b99acf44337 100644
> --- a/drivers/net/phy/mxl-gpy.c
> +++ b/drivers/net/phy/mxl-gpy.c
> @@ -8,7 +8,9 @@
>  
>  #include <linux/module.h>
>  #include <linux/bitfield.h>
> +#include <linux/hwmon.h>
>  #include <linux/phy.h>
> +#include <linux/polynomial.h>
>  #include <linux/netdevice.h>
>  
>  /* PHY ID */
> @@ -64,6 +66,10 @@
>  #define VSPEC1_SGMII_ANEN_ANRS	(VSPEC1_SGMII_CTRL_ANEN | \
>  				 VSPEC1_SGMII_CTRL_ANRS)
>  
> +/* Temperature sensor */
> +#define VPSPEC1_TEMP_STA	0x0E
> +#define VPSPEC1_TEMP_STA_DATA	GENMASK(9, 0)
> +
>  /* WoL */
>  #define VPSPEC2_WOL_CTL		0x0E06
>  #define VPSPEC2_WOL_AD01	0x0E08
> @@ -80,6 +86,102 @@ static const struct {
>  	{9, 0x73},
>  };
>  
> +#if IS_ENABLED(CONFIG_HWMON)
> +/* The original translation formulae of the temperature (in degrees of Celsius)
> + * are as follows:
> + *
> + *   T = -2.5761e-11*(N^4) + 9.7332e-8*(N^3) + -1.9165e-4*(N^2) +
> + *       3.0762e-1*(N^1) + -5.2156e1
> + *
> + * where [-52.156, 137.961]C and N = [0, 1023].
> + *
> + * They must be accordingly altered to be suitable for the integer arithmetics.
> + * The technique is called 'factor redistribution', which just makes sure the
> + * multiplications and divisions are made so to have a result of the operations
> + * within the integer numbers limit. In addition we need to translate the
> + * formulae to accept millidegrees of Celsius. Here what it looks like after
> + * the alterations:
> + *
> + *   T = -25761e-12*(N^4) + 97332e-9*(N^3) + -191650e-6*(N^2) +
> + *       307620e-3*(N^1) + -52156
> + *
> + * where T = [-52156, 137961]mC and N = [0, 1023].
> + */
> +static const struct polynomial poly_N_to_temp = {
> +	.terms = {
> +		{4,  -25761, 1000, 1},
> +		{3,   97332, 1000, 1},
> +		{2, -191650, 1000, 1},
> +		{1,  307620, 1000, 1},
> +		{0,  -52156,    1, 1}
> +	}
> +};
> +
> +static int gpy_hwmon_read(struct device *dev,
> +			  enum hwmon_sensor_types type,
> +			  u32 attr, int channel, long *value)
> +{
> +	struct phy_device *phydev = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = phy_read_mmd(phydev, MDIO_MMD_VEND1, VPSPEC1_TEMP_STA);
> +	if (ret < 0)
> +		return ret;
> +	if (!ret)
> +		return -ENODATA;
> +
> +	*value = polynomial_calc(&poly_N_to_temp,
> +				 FIELD_GET(VPSPEC1_TEMP_STA_DATA, ret));
> +
> +	return 0;
> +}
> +
> +static umode_t gpy_hwmon_is_visible(const void *data,
> +				    enum hwmon_sensor_types type,
> +				    u32 attr, int channel)
> +{
> +	return 0444;
> +}
> +
> +static const struct hwmon_channel_info *gpy_hwmon_info[] = {
> +	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
> +	NULL
> +};
> +
> +static const struct hwmon_ops gpy_hwmon_hwmon_ops = {
> +	.is_visible	= gpy_hwmon_is_visible,
> +	.read		= gpy_hwmon_read,
> +};
> +
> +static const struct hwmon_chip_info gpy_hwmon_chip_info = {
> +	.ops		= &gpy_hwmon_hwmon_ops,
> +	.info		= gpy_hwmon_info,
> +};
> +
> +static int gpy_hwmon_register(struct phy_device *phydev)
> +{
> +	struct device *dev = &phydev->mdio.dev;
> +	struct device *hwmon_dev;
> +	char *hwmon_name;
> +
> +	hwmon_name = devm_hwmon_sanitize_name(dev, dev_name(dev));
> +	if (IS_ERR(hwmon_name))
> +		return PTR_ERR(hwmon_name);
> +
> +	hwmon_dev = devm_hwmon_device_register_with_info(dev, hwmon_name,
> +							 phydev,
> +							 &gpy_hwmon_chip_info,
> +							 NULL);
> +
> +	return PTR_ERR_OR_ZERO(hwmon_dev);
> +}
> +#else
> +static int gpy_hwmon_register(struct phy_device *phydev)
> +{
> +	return 0;
> +}
> +#endif
> +
>  static int gpy_config_init(struct phy_device *phydev)
>  {
>  	int ret;
> @@ -109,6 +211,10 @@ static int gpy_probe(struct phy_device *phydev)
>  	if (ret < 0)
>  		return ret;
>  
> +	ret = gpy_hwmon_register(phydev);
> +	if (ret)
> +		return ret;
> +
>  	phydev_info(phydev, "Firmware Version: 0x%04X (%s)\n", ret,
>  		    (ret & PHY_FWV_REL_MASK) ? "release" : "test");
>  
> -- 
> 2.30.2
>