diff mbox series

[v2,net-next] net: ethernet: ti: davinci_mdio: Add workaround for errata i2329

Message ID 20220810111345.31200-1-r-gunasekaran@ti.com (mailing list archive)
State New, archived
Headers show
Series [v2,net-next] net: ethernet: ti: davinci_mdio: Add workaround for errata i2329 | expand

Commit Message

Ravi Gunasekaran Aug. 10, 2022, 11:13 a.m. UTC
On the CPSW and ICSS peripherals, there is a possibility that the MDIO
interface returns corrupt data on MDIO reads or writes incorrect data
on MDIO writes. There is also a possibility for the MDIO interface to
become unavailable until the next peripheral reset.

The workaround is to configure the MDIO in manual mode and disable the
MDIO state machine and emulate the MDIO protocol by reading and writing
appropriate fields in MDIO_MANUAL_IF_REG register of the MDIO controller
to manipulate the MDIO clock and data pins.

More details about the errata i2329 and the workaround is available in:
https://www.ti.com/lit/er/sprz487a/sprz487a.pdf

Add implementation to disable MDIO state machine, configure MDIO in manual
mode and achieve MDIO read and writes via MDIO Bitbanging

Signed-off-by: Ravi Gunasekaran <r-gunasekaran@ti.com>
---
Changelog:
v1 -> v2:
1. Use the existing MDIO bitbang framework

v1: https://lore.kernel.org/netdev/20220808111229.11951-1-r-gunasekaran@ti.com/

 drivers/net/ethernet/ti/davinci_mdio.c | 255 +++++++++++++++++++++++--
 1 file changed, 244 insertions(+), 11 deletions(-)

Comments

Andrew Lunn Aug. 11, 2022, 12:30 a.m. UTC | #1
> +static int davinci_mdiobb_read(struct mii_bus *bus, int phy, int reg)
> +{
> +	int ret;
> +	struct mdiobb_ctrl *ctrl = bus->priv;
> +	struct davinci_mdio_data *data;
> +
> +	data = container_of(ctrl, struct davinci_mdio_data, bb_ctrl);
> +
> +	if (phy & ~PHY_REG_MASK || reg & ~PHY_ID_MASK)
> +		return -EINVAL;

You don't need this. Leave it up to the bit banging code to do the
validation. This also breaks C45, which the bit banging code can do,
and it looks like the hardware cannot.

> +
> +	ret = pm_runtime_resume_and_get(data->dev);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = mdiobb_read(bus, phy, reg);
> +
> +	pm_runtime_mark_last_busy(data->dev);
> +	pm_runtime_put_autosuspend(data->dev);

Once you take the validation out, this function then all becomes about
runtime power management. Should the bit banging core actually be
doing this? It seems like it is something which could be useful for
other devices.

struct mii_bus has a parent member. If set, you could apply these run
time PM functions to that. Please add a patch to modify the core bit
banging code, and then you should be able to remove these helpers.

>  static int davinci_mdio_probe(struct platform_device *pdev)
>  {
>  	struct mdio_platform_data *pdata = dev_get_platdata(&pdev->dev);
> @@ -340,12 +535,30 @@ static int davinci_mdio_probe(struct platform_device *pdev)
>  	struct phy_device *phy;
>  	int ret, addr;
>  	int autosuspend_delay_ms = -1;
> +	const struct soc_device_attribute *soc_match_data;

netdev uses reverse christmas tree. Variables should be sorted longest
first, shortest last.

       Andrew
Ravi Gunasekaran Aug. 11, 2022, 7 a.m. UTC | #2
On 11/08/22 6:00 am, Andrew Lunn wrote:
>> +static int davinci_mdiobb_read(struct mii_bus *bus, int phy, int reg)
>> +{
>> +	int ret;
>> +	struct mdiobb_ctrl *ctrl = bus->priv;
>> +	struct davinci_mdio_data *data;
>> +
>> +	data = container_of(ctrl, struct davinci_mdio_data, bb_ctrl);
>> +
>> +	if (phy & ~PHY_REG_MASK || reg & ~PHY_ID_MASK)
>> +		return -EINVAL;
> 
> You don't need this. Leave it up to the bit banging code to do the
> validation. This also breaks C45, which the bit banging code can do,
> and it looks like the hardware cannot.

I will remove these validation.

>> +
>> +	ret = pm_runtime_resume_and_get(data->dev);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	ret = mdiobb_read(bus, phy, reg);
>> +
>> +	pm_runtime_mark_last_busy(data->dev);
>> +	pm_runtime_put_autosuspend(data->dev);
> 
> Once you take the validation out, this function then all becomes about
> runtime power management. Should the bit banging core actually be
> doing this? It seems like it is something which could be useful for
> other devices.
> 
> struct mii_bus has a parent member. If set, you could apply these run
> time PM functions to that. Please add a patch to modify the core bit
> banging code, and then you should be able to remove these helpers.

Devices may or may not be configured for runtime autosuspend, and 
perhaps may not even use runtime PM. pm_runtime_enabled() and the 
autosuspend configuration could be addressed by checking against 
dev->power.use_autosuspend flag. But if the runtime PM functions are 
added to the bit banging core, would it not restrict the usage of 
pm_runtime_put_*() variants for others?

There is atleast one device sh_eth, which is not configured for 
autosuspend but uses the bit bang core in sh_mdiobb_read() and invokes 
regular runtime PM functions.

>>   static int davinci_mdio_probe(struct platform_device *pdev)
>>   {
>>   	struct mdio_platform_data *pdata = dev_get_platdata(&pdev->dev);
>> @@ -340,12 +535,30 @@ static int davinci_mdio_probe(struct platform_device *pdev)
>>   	struct phy_device *phy;
>>   	int ret, addr;
>>   	int autosuspend_delay_ms = -1;
>> +	const struct soc_device_attribute *soc_match_data;
> 
> netdev uses reverse christmas tree. Variables should be sorted longest
> first, shortest last.

Noted. I will fix this as well.
Andrew Lunn Aug. 11, 2022, 12:57 p.m. UTC | #3
> Devices may or may not be configured for runtime autosuspend, and perhaps
> may not even use runtime PM. pm_runtime_enabled() and the autosuspend
> configuration could be addressed by checking against
> dev->power.use_autosuspend flag. But if the runtime PM functions are added
> to the bit banging core, would it not restrict the usage of
> pm_runtime_put_*() variants for others?

My assumption is, any calls to pm_runtime_* functions will effectively
do nothing if the driver does not have support for it. I could be
wrong about this, and it jumps through a NULL pointer and explodes,
but that would be a bad design.

> There is atleast one device sh_eth, which is not configured for autosuspend
> but uses the bit bang core in sh_mdiobb_read() and invokes regular runtime
> PM functions.

And that is the point of moving it into the core. It would of just
worked for you.

If you don't feel comfortable with making this unconditional, please
put runtime pm enabled version of mdiobb_read/mdiobb_write() in the
core and swap sh_eth and any other drivers to using them.

       Andrew
Ravi Gunasekaran Aug. 12, 2022, 4:36 a.m. UTC | #4
>> There is atleast one device sh_eth, which is not configured for autosuspend
>> but uses the bit bang core in sh_mdiobb_read() and invokes regular runtime
>> PM functions.
> 
> And that is the point of moving it into the core. It would of just
> worked for you.
> 
> If you don't feel comfortable with making this unconditional, please
> put runtime pm enabled version of mdiobb_read/mdiobb_write() in the
> core and swap sh_eth and any other drivers to using them.
> 

sh_eth is not configured for autosuspend and uses only pm_runtime_put().
davinci_mdio is configured for autosuspend and it must invoke 
pm_runtime_mark_last_busy() before calling pm_runtime_put_autosuspend().
So it looks like, there needs to be a runtime PM version of 
mdiobb_read/mdiobb_write() for each pm_runtime_put_*(). As of now, it's 
only sh_eth which is currently using runtime PM and davinci_mdio would 
be the next one. So at least in this case, two variants of 
mdiobb_read/mdiobb_write() could be added at the moment. By checking 
against the dev->power.use_autosuspend flag, it is possible to support 
both via a single version.

That being said, I'm quite inclined towards the existing implementation, 
where drivers can have wrappers written around 
mdiobb_read/mdiobb_write(). But I might be failing to see the broader 
picture. If having multiple runtime PM versions of 
mdiobb_read/mdiobb_write() benefits many other future drivers, then I 
will go ahead and add the variant(s) in the bitbang core.

Please provide your views on this. Your inputs on the next course of 
action would be helpful.
Andrew Lunn Aug. 12, 2022, 3:54 p.m. UTC | #5
> sh_eth is not configured for autosuspend and uses only pm_runtime_put().

I don't know the runtime power management code very well. We should
probably ask somebody how does. However:

https://elixir.bootlin.com/linux/latest/source/drivers/base/power/runtime.c#L168

This suggests it should be safe to perform an auto suspend on a device
which is not configured for auto suspend. To me, it looks like is
should directly suspend.

Devices are in a tree. If you suspend a leaf, you can walk up the tree
and suspend its parent as well, if it is not needed. Similarly, if you
wake a leaf, you need its parents awake as well, so you need to walk
up the tree and wake them. In order for this to work reliably, i
expect runtime PM to be very tolerant. If a device is not configured
for runtime PM, actions should be a NOP. If it is not configured for
auto suspend, and you ask it to auto suspend, to me, it would make
sense for it to immediately suspend, etc.

> Please provide your views on this. Your inputs on the next course of action
> would be helpful.

I would suggest you talk to somebody who knows about runtime PM.

  Andrew
kernel test robot Aug. 13, 2022, 12:57 a.m. UTC | #6
Hi Ravi,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on net-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Ravi-Gunasekaran/net-ethernet-ti-davinci_mdio-Add-workaround-for-errata-i2329/20220810-191718
base:   https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git f86d1fbbe7858884d6754534a0afbb74fc30bc26
config: arm-randconfig-r026-20220810 (https://download.01.org/0day-ci/archive/20220813/202208130814.216FrNfX-lkp@intel.com/config)
compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 5f1c7e2cc5a3c07cbc2412e851a7283c1841f520)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install arm cross compiling tool for clang build
        # apt-get install binutils-arm-linux-gnueabi
        # https://github.com/intel-lab-lkp/linux/commit/c62c93111418d5468f6add98d244f0a594dbe352
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Ravi-Gunasekaran/net-ethernet-ti-davinci_mdio-Add-workaround-for-errata-i2329/20220810-191718
        git checkout c62c93111418d5468f6add98d244f0a594dbe352
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash drivers/net/ethernet/ti/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

>> drivers/net/ethernet/ti/davinci_mdio.c:548:37: error: use of undeclared identifier 'k3_mdio_socinfo'
                   soc_match_data = soc_device_match(k3_mdio_socinfo);
                                                     ^
>> drivers/net/ethernet/ti/davinci_mdio.c:553:31: error: incomplete definition of type 'struct k3_mdio_soc_data'
                           data->manual_mode = socdata->manual_mode;
                                               ~~~~~~~^
   drivers/net/ethernet/ti/davinci_mdio.c:550:17: note: forward declaration of 'struct k3_mdio_soc_data'
                           const struct k3_mdio_soc_data *socdata =
                                        ^
   2 errors generated.


vim +/k3_mdio_socinfo +548 drivers/net/ethernet/ti/davinci_mdio.c

   528	
   529	static int davinci_mdio_probe(struct platform_device *pdev)
   530	{
   531		struct mdio_platform_data *pdata = dev_get_platdata(&pdev->dev);
   532		struct device *dev = &pdev->dev;
   533		struct davinci_mdio_data *data;
   534		struct resource *res;
   535		struct phy_device *phy;
   536		int ret, addr;
   537		int autosuspend_delay_ms = -1;
   538		const struct soc_device_attribute *soc_match_data;
   539	
   540		data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
   541		if (!data)
   542			return -ENOMEM;
   543	
   544		data->manual_mode = false;
   545		data->bb_ctrl.ops = &davinci_mdiobb_ops;
   546	
   547		if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
 > 548			soc_match_data = soc_device_match(k3_mdio_socinfo);
   549			if (soc_match_data && soc_match_data->data) {
   550				const struct k3_mdio_soc_data *socdata =
   551							soc_match_data->data;
   552	
 > 553				data->manual_mode = socdata->manual_mode;
   554			}
   555		}
   556	
   557		if (data->manual_mode)
   558			data->bus = alloc_mdio_bitbang(&data->bb_ctrl);
   559		else
   560			data->bus = devm_mdiobus_alloc(dev);
   561	
   562		if (!data->bus) {
   563			dev_err(dev, "failed to alloc mii bus\n");
   564			return -ENOMEM;
   565		}
   566	
   567		if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
   568			const struct davinci_mdio_of_param *of_mdio_data;
   569	
   570			ret = davinci_mdio_probe_dt(&data->pdata, pdev);
   571			if (ret)
   572				return ret;
   573			snprintf(data->bus->id, MII_BUS_ID_SIZE, "%s", pdev->name);
   574	
   575			of_mdio_data = of_device_get_match_data(&pdev->dev);
   576			if (of_mdio_data) {
   577				autosuspend_delay_ms =
   578						of_mdio_data->autosuspend_delay_ms;
   579			}
   580		} else {
   581			data->pdata = pdata ? (*pdata) : default_pdata;
   582			snprintf(data->bus->id, MII_BUS_ID_SIZE, "%s-%x",
   583				 pdev->name, pdev->id);
   584		}
   585	
   586		data->bus->name		= dev_name(dev);
   587	
   588		if (data->manual_mode) {
   589			data->bus->read		= davinci_mdiobb_read;
   590			data->bus->write	= davinci_mdiobb_write;
   591			data->bus->reset	= davinci_mdiobb_reset;
   592	
   593			dev_info(dev, "Configuring MDIO in manual mode\n");
   594		} else {
   595			data->bus->read		= davinci_mdio_read;
   596			data->bus->write	= davinci_mdio_write;
   597			data->bus->reset	= davinci_mdio_reset;
   598			data->bus->priv		= data;
   599		}
   600		data->bus->parent	= dev;
   601	
   602		data->clk = devm_clk_get(dev, "fck");
   603		if (IS_ERR(data->clk)) {
   604			dev_err(dev, "failed to get device clock\n");
   605			return PTR_ERR(data->clk);
   606		}
   607	
   608		dev_set_drvdata(dev, data);
   609		data->dev = dev;
   610	
   611		res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
   612		if (!res)
   613			return -EINVAL;
   614		data->regs = devm_ioremap(dev, res->start, resource_size(res));
   615		if (!data->regs)
   616			return -ENOMEM;
   617	
   618		davinci_mdio_init_clk(data);
   619	
   620		pm_runtime_set_autosuspend_delay(&pdev->dev, autosuspend_delay_ms);
   621		pm_runtime_use_autosuspend(&pdev->dev);
   622		pm_runtime_enable(&pdev->dev);
   623	
   624		/* register the mii bus
   625		 * Create PHYs from DT only in case if PHY child nodes are explicitly
   626		 * defined to support backward compatibility with DTs which assume that
   627		 * Davinci MDIO will always scan the bus for PHYs detection.
   628		 */
   629		if (dev->of_node && of_get_child_count(dev->of_node))
   630			data->skip_scan = true;
   631	
   632		ret = of_mdiobus_register(data->bus, dev->of_node);
   633		if (ret)
   634			goto bail_out;
   635	
   636		/* scan and dump the bus */
   637		for (addr = 0; addr < PHY_MAX_ADDR; addr++) {
   638			phy = mdiobus_get_phy(data->bus, addr);
   639			if (phy) {
   640				dev_info(dev, "phy[%d]: device %s, driver %s\n",
   641					 phy->mdio.addr, phydev_name(phy),
   642					 phy->drv ? phy->drv->name : "unknown");
   643			}
   644		}
   645	
   646		return 0;
   647	
   648	bail_out:
   649		pm_runtime_dont_use_autosuspend(&pdev->dev);
   650		pm_runtime_disable(&pdev->dev);
   651		return ret;
   652	}
   653
Ravi Gunasekaran Aug. 16, 2022, 4:26 a.m. UTC | #7
On 12/08/22 9:24 pm, Andrew Lunn wrote:
>> sh_eth is not configured for autosuspend and uses only pm_runtime_put().
> 
> I don't know the runtime power management code very well. We should
> probably ask somebody how does. However:
> 
> https://elixir.bootlin.com/linux/latest/source/drivers/base/power/runtime.c#L168
> 
> This suggests it should be safe to perform an auto suspend on a device
> which is not configured for auto suspend. To me, it looks like is
> should directly suspend.

I checked the pm_runtime_put() and pm_runtime_put_autosuspend() and I 
have quite a few unanswered questions. I do not have much knowledge 
about the runtime PM, so I'm not confident about adding the runtime PM 
mdiobb_read/mdiobb_write variants in the mdio bitbang core. I would 
rather take a safe approach for now and stick with the implementation 
submitted in this v2 patch.

Thanks for your feedback on this submission so far. I will fix the two 
other comments and send out a v3 patch.
diff mbox series

Patch

diff --git a/drivers/net/ethernet/ti/davinci_mdio.c b/drivers/net/ethernet/ti/davinci_mdio.c
index ea3772618043..387244e6332b 100644
--- a/drivers/net/ethernet/ti/davinci_mdio.c
+++ b/drivers/net/ethernet/ti/davinci_mdio.c
@@ -26,6 +26,8 @@ 
 #include <linux/of_device.h>
 #include <linux/of_mdio.h>
 #include <linux/pinctrl/consumer.h>
+#include <linux/mdio-bitbang.h>
+#include <linux/sys_soc.h>
 
 /*
  * This timeout definition is a worst-case ultra defensive measure against
@@ -41,6 +43,7 @@ 
 
 struct davinci_mdio_of_param {
 	int autosuspend_delay_ms;
+	bool manual_mode;
 };
 
 struct davinci_mdio_regs {
@@ -49,6 +52,15 @@  struct davinci_mdio_regs {
 #define CONTROL_IDLE		BIT(31)
 #define CONTROL_ENABLE		BIT(30)
 #define CONTROL_MAX_DIV		(0xffff)
+#define CONTROL_CLKDIV		GENMASK(15, 0)
+
+#define MDIO_MAN_MDCLK_O	BIT(2)
+#define MDIO_MAN_OE		BIT(1)
+#define MDIO_MAN_PIN		BIT(0)
+#define MDIO_MANUALMODE		BIT(31)
+
+#define MDIO_PIN               0
+
 
 	u32	alive;
 	u32	link;
@@ -59,7 +71,9 @@  struct davinci_mdio_regs {
 	u32	userintmasked;
 	u32	userintmaskset;
 	u32	userintmaskclr;
-	u32	__reserved_1[20];
+	u32	manualif;
+	u32	poll;
+	u32	__reserved_1[18];
 
 	struct {
 		u32	access;
@@ -90,6 +104,8 @@  struct davinci_mdio_data {
 	 */
 	bool		skip_scan;
 	u32		clk_div;
+	bool		manual_mode;
+	struct mdiobb_ctrl	bb_ctrl;
 };
 
 static void davinci_mdio_init_clk(struct davinci_mdio_data *data)
@@ -128,9 +144,136 @@  static void davinci_mdio_enable(struct davinci_mdio_data *data)
 	writel(data->clk_div | CONTROL_ENABLE, &data->regs->control);
 }
 
-static int davinci_mdio_reset(struct mii_bus *bus)
+static void davinci_mdio_disable(struct davinci_mdio_data *data)
+{
+	u32 reg;
+
+	/* Disable MDIO state machine */
+	reg = readl(&data->regs->control);
+
+	reg &= ~CONTROL_CLKDIV;
+	reg |= data->clk_div;
+
+	reg &= ~CONTROL_ENABLE;
+	writel(reg, &data->regs->control);
+}
+
+static void davinci_mdio_enable_manual_mode(struct davinci_mdio_data *data)
+{
+	u32 reg;
+	/* set manual mode */
+	reg = readl(&data->regs->poll);
+	reg |= MDIO_MANUALMODE;
+	writel(reg, &data->regs->poll);
+}
+
+static void davinci_set_mdc(struct mdiobb_ctrl *ctrl, int level)
+{
+	struct davinci_mdio_data *data;
+	u32 reg;
+
+	data = container_of(ctrl, struct davinci_mdio_data, bb_ctrl);
+	reg = readl(&data->regs->manualif);
+
+	if (level)
+		reg |= MDIO_MAN_MDCLK_O;
+	else
+		reg &= ~MDIO_MAN_MDCLK_O;
+
+	writel(reg, &data->regs->manualif);
+}
+
+static void davinci_set_mdio_dir(struct mdiobb_ctrl *ctrl, int output)
+{
+	struct davinci_mdio_data *data;
+	u32 reg;
+
+	data = container_of(ctrl, struct davinci_mdio_data, bb_ctrl);
+	reg = readl(&data->regs->manualif);
+
+	if (output)
+		reg |= MDIO_MAN_OE;
+	else
+		reg &= ~MDIO_MAN_OE;
+
+	writel(reg, &data->regs->manualif);
+}
+
+static void  davinci_set_mdio_data(struct mdiobb_ctrl *ctrl, int value)
+{
+	struct davinci_mdio_data *data;
+	u32 reg;
+
+	data = container_of(ctrl, struct davinci_mdio_data, bb_ctrl);
+	reg = readl(&data->regs->manualif);
+
+	if (value)
+		reg |= MDIO_MAN_PIN;
+	else
+		reg &= ~MDIO_MAN_PIN;
+
+	writel(reg, &data->regs->manualif);
+}
+
+static int davinci_get_mdio_data(struct mdiobb_ctrl *ctrl)
+{
+	struct davinci_mdio_data *data;
+	unsigned long reg;
+
+	data = container_of(ctrl, struct davinci_mdio_data, bb_ctrl);
+	reg = readl(&data->regs->manualif);
+	return test_bit(MDIO_PIN, &reg);
+}
+
+static int davinci_mdiobb_read(struct mii_bus *bus, int phy, int reg)
+{
+	int ret;
+	struct mdiobb_ctrl *ctrl = bus->priv;
+	struct davinci_mdio_data *data;
+
+	data = container_of(ctrl, struct davinci_mdio_data, bb_ctrl);
+
+	if (phy & ~PHY_REG_MASK || reg & ~PHY_ID_MASK)
+		return -EINVAL;
+
+	ret = pm_runtime_resume_and_get(data->dev);
+	if (ret < 0)
+		return ret;
+
+	ret = mdiobb_read(bus, phy, reg);
+
+	pm_runtime_mark_last_busy(data->dev);
+	pm_runtime_put_autosuspend(data->dev);
+
+	return ret;
+}
+
+static int davinci_mdiobb_write(struct mii_bus *bus, int phy, int reg,
+				u16 val)
+{
+	int ret;
+	struct mdiobb_ctrl *ctrl = bus->priv;
+	struct davinci_mdio_data *data;
+
+	data = container_of(ctrl, struct davinci_mdio_data, bb_ctrl);
+
+	if (phy & ~PHY_REG_MASK || reg & ~PHY_ID_MASK)
+		return -EINVAL;
+
+	ret = pm_runtime_resume_and_get(data->dev);
+	if (ret < 0)
+		return ret;
+
+	ret = mdiobb_write(bus, phy, reg, val);
+
+	pm_runtime_mark_last_busy(data->dev);
+	pm_runtime_put_autosuspend(data->dev);
+
+	return ret;
+}
+
+static int davinci_mdio_common_reset(struct davinci_mdio_data *data)
 {
-	struct davinci_mdio_data *data = bus->priv;
 	u32 phy_mask, ver;
 	int ret;
 
@@ -138,6 +281,11 @@  static int davinci_mdio_reset(struct mii_bus *bus)
 	if (ret < 0)
 		return ret;
 
+	if (data->manual_mode) {
+		davinci_mdio_disable(data);
+		davinci_mdio_enable_manual_mode(data);
+	}
+
 	/* wait for scan logic to settle */
 	msleep(PHY_MAX_ADDR * data->access_time);
 
@@ -171,6 +319,23 @@  static int davinci_mdio_reset(struct mii_bus *bus)
 	return 0;
 }
 
+static int davinci_mdio_reset(struct mii_bus *bus)
+{
+	struct davinci_mdio_data *data = bus->priv;
+
+	return davinci_mdio_common_reset(data);
+}
+
+static int davinci_mdiobb_reset(struct mii_bus *bus)
+{
+	struct mdiobb_ctrl *ctrl = bus->priv;
+	struct davinci_mdio_data *data;
+
+	data = container_of(ctrl, struct davinci_mdio_data, bb_ctrl);
+
+	return davinci_mdio_common_reset(data);
+}
+
 /* wait until hardware is ready for another user access */
 static inline int wait_for_user_access(struct davinci_mdio_data *data)
 {
@@ -319,6 +484,28 @@  static int davinci_mdio_probe_dt(struct mdio_platform_data *data,
 }
 
 #if IS_ENABLED(CONFIG_OF)
+struct k3_mdio_soc_data {
+	bool manual_mode;
+};
+
+static const struct k3_mdio_soc_data am65_mdio_soc_data = {
+	.manual_mode = true,
+};
+
+static const struct soc_device_attribute k3_mdio_socinfo[] = {
+	{ .family = "AM62X", .revision = "SR1.0", .data = &am65_mdio_soc_data },
+	{ .family = "AM64X", .revision = "SR1.0", .data = &am65_mdio_soc_data },
+	{ .family = "AM64X", .revision = "SR2.0", .data = &am65_mdio_soc_data },
+	{ .family = "AM65X", .revision = "SR1.0", .data = &am65_mdio_soc_data },
+	{ .family = "AM65X", .revision = "SR2.0", .data = &am65_mdio_soc_data },
+	{ .family = "J7200", .revision = "SR1.0", .data = &am65_mdio_soc_data },
+	{ .family = "J7200", .revision = "SR2.0", .data = &am65_mdio_soc_data },
+	{ .family = "J721E", .revision = "SR1.0", .data = &am65_mdio_soc_data },
+	{ .family = "J721E", .revision = "SR2.0", .data = &am65_mdio_soc_data },
+	{ .family = "J721S2", .revision = "SR1.0", .data = &am65_mdio_soc_data},
+	{ /* sentinel */ },
+};
+
 static const struct davinci_mdio_of_param of_cpsw_mdio_data = {
 	.autosuspend_delay_ms = 100,
 };
@@ -331,6 +518,14 @@  static const struct of_device_id davinci_mdio_of_mtable[] = {
 MODULE_DEVICE_TABLE(of, davinci_mdio_of_mtable);
 #endif
 
+static const struct mdiobb_ops davinci_mdiobb_ops = {
+	.owner = THIS_MODULE,
+	.set_mdc = davinci_set_mdc,
+	.set_mdio_dir = davinci_set_mdio_dir,
+	.set_mdio_data = davinci_set_mdio_data,
+	.get_mdio_data = davinci_get_mdio_data,
+};
+
 static int davinci_mdio_probe(struct platform_device *pdev)
 {
 	struct mdio_platform_data *pdata = dev_get_platdata(&pdev->dev);
@@ -340,12 +535,30 @@  static int davinci_mdio_probe(struct platform_device *pdev)
 	struct phy_device *phy;
 	int ret, addr;
 	int autosuspend_delay_ms = -1;
+	const struct soc_device_attribute *soc_match_data;
 
 	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
 
-	data->bus = devm_mdiobus_alloc(dev);
+	data->manual_mode = false;
+	data->bb_ctrl.ops = &davinci_mdiobb_ops;
+
+	if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
+		soc_match_data = soc_device_match(k3_mdio_socinfo);
+		if (soc_match_data && soc_match_data->data) {
+			const struct k3_mdio_soc_data *socdata =
+						soc_match_data->data;
+
+			data->manual_mode = socdata->manual_mode;
+		}
+	}
+
+	if (data->manual_mode)
+		data->bus = alloc_mdio_bitbang(&data->bb_ctrl);
+	else
+		data->bus = devm_mdiobus_alloc(dev);
+
 	if (!data->bus) {
 		dev_err(dev, "failed to alloc mii bus\n");
 		return -ENOMEM;
@@ -371,11 +584,20 @@  static int davinci_mdio_probe(struct platform_device *pdev)
 	}
 
 	data->bus->name		= dev_name(dev);
-	data->bus->read		= davinci_mdio_read;
-	data->bus->write	= davinci_mdio_write;
-	data->bus->reset	= davinci_mdio_reset;
+
+	if (data->manual_mode) {
+		data->bus->read		= davinci_mdiobb_read;
+		data->bus->write	= davinci_mdiobb_write;
+		data->bus->reset	= davinci_mdiobb_reset;
+
+		dev_info(dev, "Configuring MDIO in manual mode\n");
+	} else {
+		data->bus->read		= davinci_mdio_read;
+		data->bus->write	= davinci_mdio_write;
+		data->bus->reset	= davinci_mdio_reset;
+		data->bus->priv		= data;
+	}
 	data->bus->parent	= dev;
-	data->bus->priv		= data;
 
 	data->clk = devm_clk_get(dev, "fck");
 	if (IS_ERR(data->clk)) {
@@ -433,9 +655,13 @@  static int davinci_mdio_remove(struct platform_device *pdev)
 {
 	struct davinci_mdio_data *data = platform_get_drvdata(pdev);
 
-	if (data->bus)
+	if (data->bus) {
 		mdiobus_unregister(data->bus);
 
+		if (data->manual_mode)
+			free_mdio_bitbang(data->bus);
+	}
+
 	pm_runtime_dont_use_autosuspend(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
 
@@ -452,7 +678,9 @@  static int davinci_mdio_runtime_suspend(struct device *dev)
 	ctrl = readl(&data->regs->control);
 	ctrl &= ~CONTROL_ENABLE;
 	writel(ctrl, &data->regs->control);
-	wait_for_idle(data);
+
+	if (!data->manual_mode)
+		wait_for_idle(data);
 
 	return 0;
 }
@@ -461,7 +689,12 @@  static int davinci_mdio_runtime_resume(struct device *dev)
 {
 	struct davinci_mdio_data *data = dev_get_drvdata(dev);
 
-	davinci_mdio_enable(data);
+	if (data->manual_mode) {
+		davinci_mdio_disable(data);
+		davinci_mdio_enable_manual_mode(data);
+	} else {
+		davinci_mdio_enable(data);
+	}
 	return 0;
 }
 #endif