[PATCH v5 0/2] ethtool: implement Energy Detect Powerdown support via phy-tunable

[PATCH v5 0/2] ethtool: implement Energy Detect Powerdown support via phy-tunable

[Alexandru Ardelean]

This changeset proposes a new control for PHY tunable to control Energy
Detect Power Down.

The `phy_tunable_id` has been named `ETHTOOL_PHY_EDPD` since it looks like
this feature is common across other PHYs (like EEE), and defining
`ETHTOOL_PHY_ENERGY_DETECT_POWER_DOWN` seems too long.
    
The way EDPD works, is that the RX block is put to a lower power mode,
except for link-pulse detection circuits. The TX block is also put to low
power mode, but the PHY wakes-up periodically to send link pulses, to avoid
lock-ups in case the other side is also in EDPD mode.
    
Currently, there are 2 PHY drivers that look like they could use this new
PHY tunable feature: the `adin` && `micrel` PHYs.

This series updates only the `adin` PHY driver to support this new feature,
as this chip has been tested. A change for `micrel` can be proposed after a
discussion of the PHY-tunable API is resolved.

Alexandru Ardelean (2):
  ethtool: implement Energy Detect Powerdown support via phy-tunable
  net: phy: adin: implement Energy Detect Powerdown mode via phy-tunable

 drivers/net/phy/adin.c       | 61 ++++++++++++++++++++++++++++++++++++
 include/uapi/linux/ethtool.h | 22 +++++++++++++
 net/core/ethtool.c           |  6 ++++
 3 files changed, 89 insertions(+)

-- 

Changelog v4 -> v5:
* add Andrew's & Florian's Reviewed-by tags for patch 1
* fixed patch 2 goof:
  `rc = adin_set_edpd(phydev, 1);`
    ->
  `rc = adin_set_edpd(phydev, ETHTOOL_PHY_EDPD_DFLT_TX_MSECS);` 
  this was omitted when re-spin to v4 was done
* for patch 2 added Florian's Reviewed-by tag as this was suggested by him
  and his accord was
  `with that fixed: Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>`

Changelog v3 -> v4:
* impose the TX interval unit for EDPD to be milliseconds; the point was
  raised by Michal; this should allow for intervals:
   - as small as 1 millisecond, which does not sound like a power-saver
   - as large as 65 seconds, which sounds like a lot to wait for a link to
     come up

Changelog v2 -> v3:
* implement Andrew's review comments:
  1. for patch `ethtool: implement Energy Detect Powerdown support via
     phy-tunable`
     - ETHTOOL_PHY_EDPD_DFLT_TX_INTERVAL == 0xffff
     - ETHTOOL_PHY_EDPD_NO_TX            == 0xfffe
     - added comment in include/uapi/linux/ethtool.h
  2. for patch `net: phy: adin: implement Energy Detect Powerdown mode via
     phy-tunable`
     - added comments about interval & units for the ADIN PHY
     - in `adin_set_edpd()`: add a switch statement of all the valid values
     - in `adin_get_edpd()`: return `ETHTOOL_PHY_EDPD_DFLT_TX_INTERVAL`
       since the PHY only supports a single TX-interval value (1 second)

Changelog v1 -> v2:
* initial series was made up of 2 sub-series: 1 for kernel & 1 for ethtool
  in userspace; v2 contains only the kernel series

2.20.1

[PATCH v5 1/2] ethtool: implement Energy Detect Powerdown support via phy-tunable

[Alexandru Ardelean]

The `phy_tunable_id` has been named `ETHTOOL_PHY_EDPD` since it looks like
this feature is common across other PHYs (like EEE), and defining
`ETHTOOL_PHY_ENERGY_DETECT_POWER_DOWN` seems too long.

The way EDPD works, is that the RX block is put to a lower power mode,
except for link-pulse detection circuits. The TX block is also put to low
power mode, but the PHY wakes-up periodically to send link pulses, to avoid
lock-ups in case the other side is also in EDPD mode.

Currently, there are 2 PHY drivers that look like they could use this new
PHY tunable feature: the `adin` && `micrel` PHYs.

The ADIN's datasheet mentions that TX pulses are at intervals of 1 second
default each, and they can be disabled. For the Micrel KSZ9031 PHY, the
datasheet does not mention whether they can be disabled, but mentions that
they can modified.

The way this change is structured, is similar to the PHY tunable downshift
control:
* a `ETHTOOL_PHY_EDPD_DFLT_TX_MSECS` value is exposed to cover a default
  TX interval; some PHYs could specify a certain value that makes sense
* `ETHTOOL_PHY_EDPD_NO_TX` would disable TX when EDPD is enabled
* `ETHTOOL_PHY_EDPD_DISABLE` will disable EDPD

As noted by the `ETHTOOL_PHY_EDPD_DFLT_TX_MSECS` the interval unit is 1
millisecond, which should cover a reasonable range of intervals:
 - from 1 millisecond, which does not sound like much of a power-saver
 - to ~65 seconds which is quite a lot to wait for a link to come up when
   plugging a cable

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
---
 include/uapi/linux/ethtool.h | 22 ++++++++++++++++++++++
 net/core/ethtool.c           |  6 ++++++
 2 files changed, 28 insertions(+)

diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
index dd06302aa93e..8938b76c4ee3 100644
--- a/include/uapi/linux/ethtool.h
+++ b/include/uapi/linux/ethtool.h
@@ -259,10 +259,32 @@ struct ethtool_tunable {
 #define ETHTOOL_PHY_FAST_LINK_DOWN_ON	0
 #define ETHTOOL_PHY_FAST_LINK_DOWN_OFF	0xff
 
+/* Energy Detect Power Down (EDPD) is a feature supported by some PHYs, where
+ * the PHY's RX & TX blocks are put into a low-power mode when there is no
+ * link detected (typically cable is un-plugged). For RX, only a minimal
+ * link-detection is available, and for TX the PHY wakes up to send link pulses
+ * to avoid any lock-ups in case the peer PHY may also be running in EDPD mode.
+ *
+ * Some PHYs may support configuration of the wake-up interval for TX pulses,
+ * and some PHYs may support only disabling TX pulses entirely. For the latter
+ * a special value is required (ETHTOOL_PHY_EDPD_NO_TX) so that this can be
+ * configured from userspace (should the user want it).
+ *
+ * The interval units for TX wake-up are in milliseconds, since this should
+ * cover a reasonable range of intervals:
+ *  - from 1 millisecond, which does not sound like much of a power-saver
+ *  - to ~65 seconds which is quite a lot to wait for a link to come up when
+ *    plugging a cable
+ */
+#define ETHTOOL_PHY_EDPD_DFLT_TX_MSECS		0xffff
+#define ETHTOOL_PHY_EDPD_NO_TX			0xfffe
+#define ETHTOOL_PHY_EDPD_DISABLE		0
+
 enum phy_tunable_id {
 	ETHTOOL_PHY_ID_UNSPEC,
 	ETHTOOL_PHY_DOWNSHIFT,
 	ETHTOOL_PHY_FAST_LINK_DOWN,
+	ETHTOOL_PHY_EDPD,
 	/*
 	 * Add your fresh new phy tunable attribute above and remember to update
 	 * phy_tunable_strings[] in net/core/ethtool.c
diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 6288e69e94fc..c763106c73fc 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -133,6 +133,7 @@ phy_tunable_strings[__ETHTOOL_PHY_TUNABLE_COUNT][ETH_GSTRING_LEN] = {
 	[ETHTOOL_ID_UNSPEC]     = "Unspec",
 	[ETHTOOL_PHY_DOWNSHIFT]	= "phy-downshift",
 	[ETHTOOL_PHY_FAST_LINK_DOWN] = "phy-fast-link-down",
+	[ETHTOOL_PHY_EDPD]	= "phy-energy-detect-power-down",
 };
 
 static int ethtool_get_features(struct net_device *dev, void __user *useraddr)
@@ -2451,6 +2452,11 @@ static int ethtool_phy_tunable_valid(const struct ethtool_tunable *tuna)
 		    tuna->type_id != ETHTOOL_TUNABLE_U8)
 			return -EINVAL;
 		break;
+	case ETHTOOL_PHY_EDPD:
+		if (tuna->len != sizeof(u16) ||
+		    tuna->type_id != ETHTOOL_TUNABLE_U16)
+			return -EINVAL;
+		break;
 	default:
 		return -EINVAL;
 	}
-- 
2.20.1

[PATCH v5 2/2] net: phy: adin: implement Energy Detect Powerdown mode via phy-tunable

[Alexandru Ardelean]

This driver becomes the first user of the kernel's `ETHTOOL_PHY_EDPD`
phy-tunable feature.
EDPD is also enabled by default on PHY config_init, but can be disabled via
the phy-tunable control.

When enabling EDPD, it's also a good idea (for the ADIN PHYs) to enable TX
periodic pulses, so that in case the other PHY is also on EDPD mode, there
is no lock-up situation where both sides are waiting for the other to
transmit.

Via the phy-tunable control, TX pulses can be disabled if specifying 0
`tx-interval` via ethtool.

The ADIN PHY supports only fixed 1 second intervals; they cannot be
configured. That is why the acceptable values are 1,
ETHTOOL_PHY_EDPD_DFLT_TX_MSECS and ETHTOOL_PHY_EDPD_NO_TX (which disables
TX pulses).

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
---
 drivers/net/phy/adin.c | 61 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/drivers/net/phy/adin.c b/drivers/net/phy/adin.c
index 4dec83df048d..cf5a391c93e6 100644
--- a/drivers/net/phy/adin.c
+++ b/drivers/net/phy/adin.c
@@ -26,6 +26,11 @@
 
 #define ADIN1300_RX_ERR_CNT			0x0014
 
+#define ADIN1300_PHY_CTRL_STATUS2		0x0015
+#define   ADIN1300_NRG_PD_EN			BIT(3)
+#define   ADIN1300_NRG_PD_TX_EN			BIT(2)
+#define   ADIN1300_NRG_PD_STATUS		BIT(1)
+
 #define ADIN1300_PHY_CTRL2			0x0016
 #define   ADIN1300_DOWNSPEED_AN_100_EN		BIT(11)
 #define   ADIN1300_DOWNSPEED_AN_10_EN		BIT(10)
@@ -328,12 +333,62 @@ static int adin_set_downshift(struct phy_device *phydev, u8 cnt)
 			    ADIN1300_DOWNSPEEDS_EN);
 }
 
+static int adin_get_edpd(struct phy_device *phydev, u16 *tx_interval)
+{
+	int val;
+
+	val = phy_read(phydev, ADIN1300_PHY_CTRL_STATUS2);
+	if (val < 0)
+		return val;
+
+	if (ADIN1300_NRG_PD_EN & val) {
+		if (val & ADIN1300_NRG_PD_TX_EN)
+			/* default is 1 second */
+			*tx_interval = ETHTOOL_PHY_EDPD_DFLT_TX_MSECS;
+		else
+			*tx_interval = ETHTOOL_PHY_EDPD_NO_TX;
+	} else {
+		*tx_interval = ETHTOOL_PHY_EDPD_DISABLE;
+	}
+
+	return 0;
+}
+
+static int adin_set_edpd(struct phy_device *phydev, u16 tx_interval)
+{
+	u16 val;
+
+	if (tx_interval == ETHTOOL_PHY_EDPD_DISABLE)
+		return phy_clear_bits(phydev, ADIN1300_PHY_CTRL_STATUS2,
+				(ADIN1300_NRG_PD_EN | ADIN1300_NRG_PD_TX_EN));
+
+	val = ADIN1300_NRG_PD_EN;
+
+	switch (tx_interval) {
+	case 1000: /* 1 second */
+		/* fallthrough */
+	case ETHTOOL_PHY_EDPD_DFLT_TX_MSECS:
+		val |= ADIN1300_NRG_PD_TX_EN;
+		/* fallthrough */
+	case ETHTOOL_PHY_EDPD_NO_TX:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return phy_modify(phydev, ADIN1300_PHY_CTRL_STATUS2,
+			  (ADIN1300_NRG_PD_EN | ADIN1300_NRG_PD_TX_EN),
+			  val);
+}
+
 static int adin_get_tunable(struct phy_device *phydev,
 			    struct ethtool_tunable *tuna, void *data)
 {
 	switch (tuna->id) {
 	case ETHTOOL_PHY_DOWNSHIFT:
 		return adin_get_downshift(phydev, data);
+	case ETHTOOL_PHY_EDPD:
+		return adin_get_edpd(phydev, data);
 	default:
 		return -EOPNOTSUPP;
 	}
@@ -345,6 +400,8 @@ static int adin_set_tunable(struct phy_device *phydev,
 	switch (tuna->id) {
 	case ETHTOOL_PHY_DOWNSHIFT:
 		return adin_set_downshift(phydev, *(const u8 *)data);
+	case ETHTOOL_PHY_EDPD:
+		return adin_set_edpd(phydev, *(const u16 *)data);
 	default:
 		return -EOPNOTSUPP;
 	}
@@ -368,6 +425,10 @@ static int adin_config_init(struct phy_device *phydev)
 	if (rc < 0)
 		return rc;
 
+	rc = adin_set_edpd(phydev, ETHTOOL_PHY_EDPD_DFLT_TX_MSECS);
+	if (rc < 0)
+		return rc;
+
 	phydev_dbg(phydev, "PHY is using mode '%s'\n",
 		   phy_modes(phydev->interface));
 
-- 
2.20.1

Re: [PATCH v5 2/2] net: phy: adin: implement Energy Detect Powerdown mode via phy-tunable

[Andrew Lunn]

On Mon, Sep 16, 2019 at 10:35:26AM +0300, Alexandru Ardelean wrote:
> This driver becomes the first user of the kernel's `ETHTOOL_PHY_EDPD`
> phy-tunable feature.
> EDPD is also enabled by default on PHY config_init, but can be disabled via
> the phy-tunable control.
> 
> When enabling EDPD, it's also a good idea (for the ADIN PHYs) to enable TX
> periodic pulses, so that in case the other PHY is also on EDPD mode, there
> is no lock-up situation where both sides are waiting for the other to
> transmit.
> 
> Via the phy-tunable control, TX pulses can be disabled if specifying 0
> `tx-interval` via ethtool.
> 
> The ADIN PHY supports only fixed 1 second intervals; they cannot be
> configured. That is why the acceptable values are 1,
> ETHTOOL_PHY_EDPD_DFLT_TX_MSECS and ETHTOOL_PHY_EDPD_NO_TX (which disables
> TX pulses).
> 
> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew

Re: [PATCH v5 0/2] ethtool: implement Energy Detect Powerdown support via phy-tunable

[David Miller]

From: Alexandru Ardelean <alexandru.ardelean@analog.com>
Date: Mon, 16 Sep 2019 10:35:24 +0300

> This changeset proposes a new control for PHY tunable to control Energy
> Detect Power Down.
> 
> The `phy_tunable_id` has been named `ETHTOOL_PHY_EDPD` since it looks like
> this feature is common across other PHYs (like EEE), and defining
> `ETHTOOL_PHY_ENERGY_DETECT_POWER_DOWN` seems too long.
>     
> The way EDPD works, is that the RX block is put to a lower power mode,
> except for link-pulse detection circuits. The TX block is also put to low
> power mode, but the PHY wakes-up periodically to send link pulses, to avoid
> lock-ups in case the other side is also in EDPD mode.
>     
> Currently, there are 2 PHY drivers that look like they could use this new
> PHY tunable feature: the `adin` && `micrel` PHYs.
> 
> This series updates only the `adin` PHY driver to support this new feature,
> as this chip has been tested. A change for `micrel` can be proposed after a
> discussion of the PHY-tunable API is resolved.

Series applied.