[PATCH 0/2] MCAN: Add support for implementing transceiver as a phy

The following series of patches add support for implementing the
transceiver as a phy of m_can_platform driver.

TCAN1042 has a standby signal that needs to be pulled high for
sending/receiving messages[1]. TCAN1043 has a enable signal along with
standby signal that needs to be pulled up for sending/receiving
messages[2], and other combinations of the two lines can be used to put the
transceiver in different states to reduce power consumption. On boards
like the AM654-idk and J721e-evm these signals are controlled using gpios.

These gpios are set in phy driver, and the transceiver can be put in
different states using phy API. The phy driver is added in the series [3].

[1] - https://www.ti.com/lit/ds/symlink/tcan1042h.pdf
[2] - https://www.ti.com/lit/ds/symlink/tcan1043-q1.pdf
[3] - https://lore.kernel.org/patchwork/project/lkml/list/?series=495365

Faiz Abbas (2):
  dt-bindings: net: can: Document transceiver implementation as phy
  can: m_can: Add support for transceiver as phy

 .../devicetree/bindings/net/can/bosch,m_can.yaml    |  3 +++
 drivers/net/can/m_can/m_can.c                       | 10 ++++++++++
 drivers/net/can/m_can/m_can.h                       |  2 ++
 drivers/net/can/m_can/m_can_platform.c              | 13 +++++++++++++
 4 files changed, 28 insertions(+)

-- 
2.17.1

From: Faiz Abbas <redacted>

Some transceivers need a configuration step (for example, pulling the
standby or enable lines) for them to start sending messages. The
transceiver can be implemented as a phy with the configuration done in the
phy driver. The bit rate limitation can the be obtained by the driver using
the phy node.

Document the above implementation in the bosch mcan bindings

Signed-off-by: Faiz Abbas <redacted>
Signed-off-by: Aswath Govindraju <redacted>
---
 Documentation/devicetree/bindings/net/can/bosch,m_can.yaml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/net/can/bosch,m_can.yaml b/Documentation/devicetree/bindings/net/can/bosch,m_can.yaml
index 798fa5fb7bb2..25f74db46bae 100644
--- a/Documentation/devicetree/bindings/net/can/bosch,m_can.yaml
+++ b/Documentation/devicetree/bindings/net/can/bosch,m_can.yaml

@@ -109,6 +109,9 @@ properties:
   can-transceiver:
     $ref: can-transceiver.yaml#
 
+  phys:
+    maxItems: 1
+
 required:
   - compatible
   - reg

-- 
2.17.1

From: Faiz Abbas <redacted>

Add support for implementing transceiver node as phy. The max_bitrate is
obtained by getting a phy attribute.

Signed-off-by: Faiz Abbas <redacted>
Signed-off-by: Aswath Govindraju <redacted>
---
 drivers/net/can/m_can/m_can.c          | 10 ++++++++++
 drivers/net/can/m_can/m_can.h          |  2 ++
 drivers/net/can/m_can/m_can_platform.c | 13 +++++++++++++
 3 files changed, 25 insertions(+)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 34073cd077e4..7d31250446c2 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c

@@ -21,6 +21,7 @@
 #include <linux/iopoll.h>
 #include <linux/can/dev.h>
 #include <linux/pinctrl/consumer.h>
+#include <linux/phy/phy.h>
 
 #include "m_can.h"
 

@@ -1514,6 +1515,7 @@ static void m_can_stop(struct net_device *dev)
 static int m_can_close(struct net_device *dev)
 {
 	struct m_can_classdev *cdev = netdev_priv(dev);
+	int err;
 
 	netif_stop_queue(dev);
 

@@ -1536,6 +1538,10 @@ static int m_can_close(struct net_device *dev)
 	close_candev(dev);
 	can_led_event(dev, CAN_LED_EVENT_STOP);
 
+	err = phy_power_off(cdev->transceiver);
+	if (err)
+		return err;
+
 	return 0;
 }
 

@@ -1720,6 +1726,10 @@ static int m_can_open(struct net_device *dev)
 	struct m_can_classdev *cdev = netdev_priv(dev);
 	int err;
 
+	err = phy_power_on(cdev->transceiver);
+	if (err)
+		return err;
+
 	err = m_can_clk_start(cdev);
 	if (err)
 		return err;

diff --git a/drivers/net/can/m_can/m_can.h b/drivers/net/can/m_can/m_can.h
index ace071c3e58c..38cad068abad 100644
--- a/drivers/net/can/m_can/m_can.h
+++ b/drivers/net/can/m_can/m_can.h

@@ -28,6 +28,7 @@
 #include <linux/iopoll.h>
 #include <linux/can/dev.h>
 #include <linux/pinctrl/consumer.h>
+#include <linux/phy/phy.h>
 
 /* m_can lec values */
 enum m_can_lec_type {

@@ -82,6 +83,7 @@ struct m_can_classdev {
 	struct workqueue_struct *tx_wq;
 	struct work_struct tx_work;
 	struct sk_buff *tx_skb;
+	struct phy *transceiver;
 
 	struct can_bittiming_const *bit_timing;
 	struct can_bittiming_const *data_timing;

diff --git a/drivers/net/can/m_can/m_can_platform.c b/drivers/net/can/m_can/m_can_platform.c
index 599de0e08cd7..006e13ee7cd7 100644
--- a/drivers/net/can/m_can/m_can_platform.c
+++ b/drivers/net/can/m_can/m_can_platform.c

@@ -6,6 +6,7 @@
 // Copyright (C) 2018-19 Texas Instruments Incorporated - http://www.ti.com/
 
 #include <linux/platform_device.h>
+#include <linux/phy/phy.h>
 
 #include "m_can.h"
 

@@ -67,6 +68,7 @@ static int m_can_plat_probe(struct platform_device *pdev)
 	struct resource *res;
 	void __iomem *addr;
 	void __iomem *mram_addr;
+	struct phy *transceiver;
 	int irq, ret = 0;
 
 	mcan_class = m_can_class_allocate_dev(&pdev->dev,

@@ -101,6 +103,16 @@ static int m_can_plat_probe(struct platform_device *pdev)
 		goto probe_fail;
 	}
 
+	transceiver = devm_of_phy_optional_get_by_index(&pdev->dev, pdev->dev.of_node, 0);
+	if (IS_ERR(transceiver)) {
+		ret = PTR_ERR(transceiver);
+		dev_err(&pdev->dev, "error while getting phy, err=%d\n", ret);
+		return ret;
+	}
+
+	if (transceiver)
+		priv->cdev.can.bitrate_max = transceiver->attrs.max_link_rate;
+
 	priv->base = addr;
 	priv->mram_base = mram_addr;
 

@@ -108,6 +120,7 @@ static int m_can_plat_probe(struct platform_device *pdev)
 	mcan_class->pm_clock_support = 1;
 	mcan_class->can.clock.freq = clk_get_rate(mcan_class->cclk);
 	mcan_class->dev = &pdev->dev;
+	mcan_class->transceiver = transceiver;
 
 	mcan_class->ops = &m_can_plat_ops;
 

-- 
2.17.1

Hi all,

On 15/04/21 8:36 pm, Aswath Govindraju wrote:

The following series of patches add support for implementing the
transceiver as a phy of m_can_platform driver.

TCAN1042 has a standby signal that needs to be pulled high for
sending/receiving messages[1]. TCAN1043 has a enable signal along with
standby signal that needs to be pulled up for sending/receiving
messages[2], and other combinations of the two lines can be used to put the
transceiver in different states to reduce power consumption. On boards
like the AM654-idk and J721e-evm these signals are controlled using gpios.

These gpios are set in phy driver, and the transceiver can be put in
different states using phy API. The phy driver is added in the series [3].

[1] - https://www.ti.com/lit/ds/symlink/tcan1042h.pdf
[2] - https://www.ti.com/lit/ds/symlink/tcan1043-q1.pdf
[3] - https://lore.kernel.org/patchwork/project/lkml/list/?series=495365

Please ignore this series. I will post a respin using
devm_phy_get_optional instead of devm_of_phy_get_optional_by_index()
based on the comments below[1]. Sorry for the noise.

[1] - https://lore.kernel.org/patchwork/patch/1413931/

Thanks,
Aswath

Faiz Abbas (2):
  dt-bindings: net: can: Document transceiver implementation as phy
  can: m_can: Add support for transceiver as phy

 .../devicetree/bindings/net/can/bosch,m_can.yaml    |  3 +++
 drivers/net/can/m_can/m_can.c                       | 10 ++++++++++
 drivers/net/can/m_can/m_can.h                       |  2 ++
 drivers/net/can/m_can/m_can_platform.c              | 13 +++++++++++++
 4 files changed, 28 insertions(+)

Hi all,

On 15/04/21 8:36 pm, Aswath Govindraju wrote:

The following series of patches add support for implementing the
transceiver as a phy of m_can_platform driver.

TCAN1042 has a standby signal that needs to be pulled high for
sending/receiving messages[1]. TCAN1043 has a enable signal along with
standby signal that needs to be pulled up for sending/receiving
messages[2], and other combinations of the two lines can be used to put the
transceiver in different states to reduce power consumption. On boards
like the AM654-idk and J721e-evm these signals are controlled using gpios.

These gpios are set in phy driver, and the transceiver can be put in
different states using phy API. The phy driver is added in the series [3].

[1] - https://www.ti.com/lit/ds/symlink/tcan1042h.pdf
[2] - https://www.ti.com/lit/ds/symlink/tcan1043-q1.pdf
[3] - https://lore.kernel.org/patchwork/project/lkml/list/?series=495365

Posted v2 for this series.

Thanks,
Aswath

Faiz Abbas (2):
  dt-bindings: net: can: Document transceiver implementation as phy
  can: m_can: Add support for transceiver as phy

 .../devicetree/bindings/net/can/bosch,m_can.yaml    |  3 +++
 drivers/net/can/m_can/m_can.c                       | 10 ++++++++++
 drivers/net/can/m_can/m_can.h                       |  2 ++
 drivers/net/can/m_can/m_can_platform.c              | 13 +++++++++++++
 4 files changed, 28 insertions(+)