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net: ethernet: ti: davinci_mdio: Add workaround for errata i2329
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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>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Ravi Gunasekaran authored and David S. Miller committed Aug 22, 2022
1 parent bb726b7 commit d04807b
Showing 1 changed file with 231 additions and 11 deletions.
242 changes: 231 additions & 11 deletions drivers/net/ethernet/ti/davinci_mdio.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -41,6 +43,7 @@

struct davinci_mdio_of_param {
int autosuspend_delay_ms;
bool manual_mode;
};

struct davinci_mdio_regs {
Expand All @@ -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;
Expand All @@ -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;
Expand All @@ -79,6 +93,7 @@ static const struct mdio_platform_data default_pdata = {

struct davinci_mdio_data {
struct mdio_platform_data pdata;
struct mdiobb_ctrl bb_ctrl;
struct davinci_mdio_regs __iomem *regs;
struct clk *clk;
struct device *dev;
Expand All @@ -90,6 +105,7 @@ struct davinci_mdio_data {
*/
bool skip_scan;
u32 clk_div;
bool manual_mode;
};

static void davinci_mdio_init_clk(struct davinci_mdio_data *data)
Expand Down Expand Up @@ -128,16 +144,134 @@ 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;

ret = pm_runtime_resume_and_get(bus->parent);
if (ret < 0)
return ret;

ret = mdiobb_read(bus, phy, reg);

pm_runtime_mark_last_busy(bus->parent);
pm_runtime_put_autosuspend(bus->parent);

return ret;
}

static int davinci_mdiobb_write(struct mii_bus *bus, int phy, int reg,
u16 val)
{
int ret;

ret = pm_runtime_resume_and_get(bus->parent);
if (ret < 0)
return ret;

ret = mdiobb_write(bus, phy, reg, val);

pm_runtime_mark_last_busy(bus->parent);
pm_runtime_put_autosuspend(bus->parent);

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;

ret = pm_runtime_resume_and_get(data->dev);
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);

Expand Down Expand Up @@ -171,6 +305,23 @@ 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)
{
Expand Down Expand Up @@ -318,6 +469,28 @@ static int davinci_mdio_probe_dt(struct mdio_platform_data *data,
return 0;
}

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 */ },
};

#if IS_ENABLED(CONFIG_OF)
static const struct davinci_mdio_of_param of_cpsw_mdio_data = {
.autosuspend_delay_ms = 100,
Expand All @@ -331,6 +504,14 @@ 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);
Expand All @@ -345,7 +526,26 @@ static int davinci_mdio_probe(struct platform_device *pdev)
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) {
const struct soc_device_attribute *soc_match_data;

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;
Expand All @@ -371,11 +571,20 @@ 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)) {
Expand Down Expand Up @@ -433,9 +642,13 @@ 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);

Expand All @@ -452,7 +665,9 @@ 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;
}
Expand All @@ -461,7 +676,12 @@ 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
Expand Down

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