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linux-stable/drivers/net/dsa/realtek-smi-core.c
Vladimir Oltean 74b6d7d133 net: dsa: realtek: register the MDIO bus under devres 
The Linux device model permits both the ->shutdown and ->remove driver
methods to get called during a shutdown procedure. Example: a DSA switch
which sits on an SPI bus, and the SPI bus driver calls this on its
->shutdown method:

spi_unregister_controller
-> device_for_each_child(&ctlr->dev, NULL, __unregister);
   -> spi_unregister_device(to_spi_device(dev));
      -> device_del(&spi->dev);

So this is a simple pattern which can theoretically appear on any bus,
although the only other buses on which I've been able to find it are
I2C:

i2c_del_adapter
-> device_for_each_child(&adap->dev, NULL, __unregister_client);
   -> i2c_unregister_device(client);
      -> device_unregister(&client->dev);

The implication of this pattern is that devices on these buses can be
unregistered after having been shut down. The drivers for these devices
might choose to return early either from ->remove or ->shutdown if the
other callback has already run once, and they might choose that the
->shutdown method should only perform a subset of the teardown done by
->remove (to avoid unnecessary delays when rebooting).

So in other words, the device driver may choose on ->remove to not
do anything (therefore to not unregister an MDIO bus it has registered
on ->probe), because this ->remove is actually triggered by the
device_shutdown path, and its ->shutdown method has already run and done
the minimally required cleanup.

This used to be fine until the blamed commit, but now, the following
BUG_ON triggers:

void mdiobus_free(struct mii_bus *bus)
{
	/* For compatibility with error handling in drivers. */
	if (bus->state == MDIOBUS_ALLOCATED) {
		kfree(bus);
		return;
	}

	BUG_ON(bus->state != MDIOBUS_UNREGISTERED);
	bus->state = MDIOBUS_RELEASED;

	put_device(&bus->dev);
}

In other words, there is an attempt to free an MDIO bus which was not
unregistered. The attempt to free it comes from the devres release
callbacks of the SPI device, which are executed after the device is
unregistered.

I'm not saying that the fact that MDIO buses allocated using devres
would automatically get unregistered wasn't strange. I'm just saying
that the commit didn't care about auditing existing call paths in the
kernel, and now, the following code sequences are potentially buggy:

(a) devm_mdiobus_alloc followed by plain mdiobus_register, for a device
    located on a bus that unregisters its children on shutdown. After
    the blamed patch, either both the alloc and the register should use
    devres, or none should.

(b) devm_mdiobus_alloc followed by plain mdiobus_register, and then no
    mdiobus_unregister at all in the remove path. After the blamed
    patch, nobody unregisters the MDIO bus anymore, so this is even more
    buggy than the previous case which needs a specific bus
    configuration to be seen, this one is an unconditional bug.

In this case, the Realtek drivers fall under category (b). To solve it,
we can register the MDIO bus under devres too, which restores the
previous behavior.

Fixes: ac3a68d566 ("net: phy: don't abuse devres in devm_mdiobus_register()")
Reported-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Reported-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-09-21 13:52:16 +01:00

519 lines
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// SPDX-License-Identifier: GPL-2.0+
/* Realtek Simple Management Interface (SMI) driver
* It can be discussed how "simple" this interface is.
*
* The SMI protocol piggy-backs the MDIO MDC and MDIO signals levels
* but the protocol is not MDIO at all. Instead it is a Realtek
* pecularity that need to bit-bang the lines in a special way to
* communicate with the switch.
*
* ASICs we intend to support with this driver:
*
* RTL8366 - The original version, apparently
* RTL8369 - Similar enough to have the same datsheet as RTL8366
* RTL8366RB - Probably reads out "RTL8366 revision B", has a quite
* different register layout from the other two
* RTL8366S - Is this "RTL8366 super"?
* RTL8367 - Has an OpenWRT driver as well
* RTL8368S - Seems to be an alternative name for RTL8366RB
* RTL8370 - Also uses SMI
*
* Copyright (C) 2017 Linus Walleij <linus.walleij@linaro.org>
* Copyright (C) 2010 Antti Seppälä <a.seppala@gmail.com>
* Copyright (C) 2010 Roman Yeryomin <roman@advem.lv>
* Copyright (C) 2011 Colin Leitner <colin.leitner@googlemail.com>
* Copyright (C) 2009-2010 Gabor Juhos <juhosg@openwrt.org>
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/spinlock.h>
#include <linux/skbuff.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_mdio.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/bitops.h>
#include <linux/if_bridge.h>
#include "realtek-smi-core.h"
#define REALTEK_SMI_ACK_RETRY_COUNT 5
#define REALTEK_SMI_HW_STOP_DELAY 25 /* msecs */
#define REALTEK_SMI_HW_START_DELAY 100 /* msecs */
static inline void realtek_smi_clk_delay(struct realtek_smi *smi)
{
ndelay(smi->clk_delay);
}
static void realtek_smi_start(struct realtek_smi *smi)
{
/* Set GPIO pins to output mode, with initial state:
* SCK = 0, SDA = 1
*/
gpiod_direction_output(smi->mdc, 0);
gpiod_direction_output(smi->mdio, 1);
realtek_smi_clk_delay(smi);
/* CLK 1: 0 -> 1, 1 -> 0 */
gpiod_set_value(smi->mdc, 1);
realtek_smi_clk_delay(smi);
gpiod_set_value(smi->mdc, 0);
realtek_smi_clk_delay(smi);
/* CLK 2: */
gpiod_set_value(smi->mdc, 1);
realtek_smi_clk_delay(smi);
gpiod_set_value(smi->mdio, 0);
realtek_smi_clk_delay(smi);
gpiod_set_value(smi->mdc, 0);
realtek_smi_clk_delay(smi);
gpiod_set_value(smi->mdio, 1);
}
static void realtek_smi_stop(struct realtek_smi *smi)
{
realtek_smi_clk_delay(smi);
gpiod_set_value(smi->mdio, 0);
gpiod_set_value(smi->mdc, 1);
realtek_smi_clk_delay(smi);
gpiod_set_value(smi->mdio, 1);
realtek_smi_clk_delay(smi);
gpiod_set_value(smi->mdc, 1);
realtek_smi_clk_delay(smi);
gpiod_set_value(smi->mdc, 0);
realtek_smi_clk_delay(smi);
gpiod_set_value(smi->mdc, 1);
/* Add a click */
realtek_smi_clk_delay(smi);
gpiod_set_value(smi->mdc, 0);
realtek_smi_clk_delay(smi);
gpiod_set_value(smi->mdc, 1);
/* Set GPIO pins to input mode */
gpiod_direction_input(smi->mdio);
gpiod_direction_input(smi->mdc);
}
static void realtek_smi_write_bits(struct realtek_smi *smi, u32 data, u32 len)
{
for (; len > 0; len--) {
realtek_smi_clk_delay(smi);
/* Prepare data */
gpiod_set_value(smi->mdio, !!(data & (1 << (len - 1))));
realtek_smi_clk_delay(smi);
/* Clocking */
gpiod_set_value(smi->mdc, 1);
realtek_smi_clk_delay(smi);
gpiod_set_value(smi->mdc, 0);
}
}
static void realtek_smi_read_bits(struct realtek_smi *smi, u32 len, u32 *data)
{
gpiod_direction_input(smi->mdio);
for (*data = 0; len > 0; len--) {
u32 u;
realtek_smi_clk_delay(smi);
/* Clocking */
gpiod_set_value(smi->mdc, 1);
realtek_smi_clk_delay(smi);
u = !!gpiod_get_value(smi->mdio);
gpiod_set_value(smi->mdc, 0);
*data |= (u << (len - 1));
}
gpiod_direction_output(smi->mdio, 0);
}
static int realtek_smi_wait_for_ack(struct realtek_smi *smi)
{
int retry_cnt;
retry_cnt = 0;
do {
u32 ack;
realtek_smi_read_bits(smi, 1, &ack);
if (ack == 0)
break;
if (++retry_cnt > REALTEK_SMI_ACK_RETRY_COUNT) {
dev_err(smi->dev, "ACK timeout\n");
return -ETIMEDOUT;
}
} while (1);
return 0;
}
static int realtek_smi_write_byte(struct realtek_smi *smi, u8 data)
{
realtek_smi_write_bits(smi, data, 8);
return realtek_smi_wait_for_ack(smi);
}
static int realtek_smi_write_byte_noack(struct realtek_smi *smi, u8 data)
{
realtek_smi_write_bits(smi, data, 8);
return 0;
}
static int realtek_smi_read_byte0(struct realtek_smi *smi, u8 *data)
{
u32 t;
/* Read data */
realtek_smi_read_bits(smi, 8, &t);
*data = (t & 0xff);
/* Send an ACK */
realtek_smi_write_bits(smi, 0x00, 1);
return 0;
}
static int realtek_smi_read_byte1(struct realtek_smi *smi, u8 *data)
{
u32 t;
/* Read data */
realtek_smi_read_bits(smi, 8, &t);
*data = (t & 0xff);
/* Send an ACK */
realtek_smi_write_bits(smi, 0x01, 1);
return 0;
}
static int realtek_smi_read_reg(struct realtek_smi *smi, u32 addr, u32 *data)
{
unsigned long flags;
u8 lo = 0;
u8 hi = 0;
int ret;
spin_lock_irqsave(&smi->lock, flags);
realtek_smi_start(smi);
/* Send READ command */
ret = realtek_smi_write_byte(smi, smi->cmd_read);
if (ret)
goto out;
/* Set ADDR[7:0] */
ret = realtek_smi_write_byte(smi, addr & 0xff);
if (ret)
goto out;
/* Set ADDR[15:8] */
ret = realtek_smi_write_byte(smi, addr >> 8);
if (ret)
goto out;
/* Read DATA[7:0] */
realtek_smi_read_byte0(smi, &lo);
/* Read DATA[15:8] */
realtek_smi_read_byte1(smi, &hi);
*data = ((u32)lo) | (((u32)hi) << 8);
ret = 0;
out:
realtek_smi_stop(smi);
spin_unlock_irqrestore(&smi->lock, flags);
return ret;
}
static int realtek_smi_write_reg(struct realtek_smi *smi,
u32 addr, u32 data, bool ack)
{
unsigned long flags;
int ret;
spin_lock_irqsave(&smi->lock, flags);
realtek_smi_start(smi);
/* Send WRITE command */
ret = realtek_smi_write_byte(smi, smi->cmd_write);
if (ret)
goto out;
/* Set ADDR[7:0] */
ret = realtek_smi_write_byte(smi, addr & 0xff);
if (ret)
goto out;
/* Set ADDR[15:8] */
ret = realtek_smi_write_byte(smi, addr >> 8);
if (ret)
goto out;
/* Write DATA[7:0] */
ret = realtek_smi_write_byte(smi, data & 0xff);
if (ret)
goto out;
/* Write DATA[15:8] */
if (ack)
ret = realtek_smi_write_byte(smi, data >> 8);
else
ret = realtek_smi_write_byte_noack(smi, data >> 8);
if (ret)
goto out;
ret = 0;
out:
realtek_smi_stop(smi);
spin_unlock_irqrestore(&smi->lock, flags);
return ret;
}
/* There is one single case when we need to use this accessor and that
* is when issueing soft reset. Since the device reset as soon as we write
* that bit, no ACK will come back for natural reasons.
*/
int realtek_smi_write_reg_noack(struct realtek_smi *smi, u32 addr,
u32 data)
{
return realtek_smi_write_reg(smi, addr, data, false);
}
EXPORT_SYMBOL_GPL(realtek_smi_write_reg_noack);
/* Regmap accessors */
static int realtek_smi_write(void *ctx, u32 reg, u32 val)
{
struct realtek_smi *smi = ctx;
return realtek_smi_write_reg(smi, reg, val, true);
}
static int realtek_smi_read(void *ctx, u32 reg, u32 *val)
{
struct realtek_smi *smi = ctx;
return realtek_smi_read_reg(smi, reg, val);
}
static const struct regmap_config realtek_smi_mdio_regmap_config = {
.reg_bits = 10, /* A4..A0 R4..R0 */
.val_bits = 16,
.reg_stride = 1,
/* PHY regs are at 0x8000 */
.max_register = 0xffff,
.reg_format_endian = REGMAP_ENDIAN_BIG,
.reg_read = realtek_smi_read,
.reg_write = realtek_smi_write,
.cache_type = REGCACHE_NONE,
};
static int realtek_smi_mdio_read(struct mii_bus *bus, int addr, int regnum)
{
struct realtek_smi *smi = bus->priv;
return smi->ops->phy_read(smi, addr, regnum);
}
static int realtek_smi_mdio_write(struct mii_bus *bus, int addr, int regnum,
u16 val)
{
struct realtek_smi *smi = bus->priv;
return smi->ops->phy_write(smi, addr, regnum, val);
}
int realtek_smi_setup_mdio(struct realtek_smi *smi)
{
struct device_node *mdio_np;
int ret;
mdio_np = of_get_compatible_child(smi->dev->of_node, "realtek,smi-mdio");
if (!mdio_np) {
dev_err(smi->dev, "no MDIO bus node\n");
return -ENODEV;
}
smi->slave_mii_bus = devm_mdiobus_alloc(smi->dev);
if (!smi->slave_mii_bus) {
ret = -ENOMEM;
goto err_put_node;
}
smi->slave_mii_bus->priv = smi;
smi->slave_mii_bus->name = "SMI slave MII";
smi->slave_mii_bus->read = realtek_smi_mdio_read;
smi->slave_mii_bus->write = realtek_smi_mdio_write;
snprintf(smi->slave_mii_bus->id, MII_BUS_ID_SIZE, "SMI-%d",
smi->ds->index);
smi->slave_mii_bus->dev.of_node = mdio_np;
smi->slave_mii_bus->parent = smi->dev;
smi->ds->slave_mii_bus = smi->slave_mii_bus;
ret = devm_of_mdiobus_register(smi->dev, smi->slave_mii_bus, mdio_np);
if (ret) {
dev_err(smi->dev, "unable to register MDIO bus %s\n",
smi->slave_mii_bus->id);
goto err_put_node;
}
return 0;
err_put_node:
of_node_put(mdio_np);
return ret;
}
static int realtek_smi_probe(struct platform_device *pdev)
{
const struct realtek_smi_variant *var;
struct device *dev = &pdev->dev;
struct realtek_smi *smi;
struct device_node *np;
int ret;
var = of_device_get_match_data(dev);
np = dev->of_node;
smi = devm_kzalloc(dev, sizeof(*smi) + var->chip_data_sz, GFP_KERNEL);
if (!smi)
return -ENOMEM;
smi->chip_data = (void *)smi + sizeof(*smi);
smi->map = devm_regmap_init(dev, NULL, smi,
&realtek_smi_mdio_regmap_config);
if (IS_ERR(smi->map)) {
ret = PTR_ERR(smi->map);
dev_err(dev, "regmap init failed: %d\n", ret);
return ret;
}
/* Link forward and backward */
smi->dev = dev;
smi->clk_delay = var->clk_delay;
smi->cmd_read = var->cmd_read;
smi->cmd_write = var->cmd_write;
smi->ops = var->ops;
dev_set_drvdata(dev, smi);
spin_lock_init(&smi->lock);
/* TODO: if power is software controlled, set up any regulators here */
/* Assert then deassert RESET */
smi->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
if (IS_ERR(smi->reset)) {
dev_err(dev, "failed to get RESET GPIO\n");
return PTR_ERR(smi->reset);
}
msleep(REALTEK_SMI_HW_STOP_DELAY);
gpiod_set_value(smi->reset, 0);
msleep(REALTEK_SMI_HW_START_DELAY);
dev_info(dev, "deasserted RESET\n");
/* Fetch MDIO pins */
smi->mdc = devm_gpiod_get_optional(dev, "mdc", GPIOD_OUT_LOW);
if (IS_ERR(smi->mdc))
return PTR_ERR(smi->mdc);
smi->mdio = devm_gpiod_get_optional(dev, "mdio", GPIOD_OUT_LOW);
if (IS_ERR(smi->mdio))
return PTR_ERR(smi->mdio);
smi->leds_disabled = of_property_read_bool(np, "realtek,disable-leds");
ret = smi->ops->detect(smi);
if (ret) {
dev_err(dev, "unable to detect switch\n");
return ret;
}
smi->ds = devm_kzalloc(dev, sizeof(*smi->ds), GFP_KERNEL);
if (!smi->ds)
return -ENOMEM;
smi->ds->dev = dev;
smi->ds->num_ports = smi->num_ports;
smi->ds->priv = smi;
smi->ds->ops = var->ds_ops;
ret = dsa_register_switch(smi->ds);
if (ret) {
dev_err(dev, "unable to register switch ret = %d\n", ret);
return ret;
}
return 0;
}
static int realtek_smi_remove(struct platform_device *pdev)
{
struct realtek_smi *smi = platform_get_drvdata(pdev);
if (!smi)
return 0;
dsa_unregister_switch(smi->ds);
if (smi->slave_mii_bus)
of_node_put(smi->slave_mii_bus->dev.of_node);
gpiod_set_value(smi->reset, 1);
platform_set_drvdata(pdev, NULL);
return 0;
}
static void realtek_smi_shutdown(struct platform_device *pdev)
{
struct realtek_smi *smi = platform_get_drvdata(pdev);
if (!smi)
return;
dsa_switch_shutdown(smi->ds);
platform_set_drvdata(pdev, NULL);
}
static const struct of_device_id realtek_smi_of_match[] = {
{
.compatible = "realtek,rtl8366rb",
.data = &rtl8366rb_variant,
},
{
/* FIXME: add support for RTL8366S and more */
.compatible = "realtek,rtl8366s",
.data = NULL,
},
{ /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, realtek_smi_of_match);
static struct platform_driver realtek_smi_driver = {
.driver = {
.name = "realtek-smi",
.of_match_table = of_match_ptr(realtek_smi_of_match),
},
.probe = realtek_smi_probe,
.remove = realtek_smi_remove,
.shutdown = realtek_smi_shutdown,
};
module_platform_driver(realtek_smi_driver);
MODULE_LICENSE("GPL");
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