Commit bb986904 authored by Tristram Ha's avatar Tristram Ha Committed by Jakub Kicinski
Browse files

net: dsa: microchip: Fix LAN937X set_ageing_time function 



The aging count is not a simple 20-bit value but comprises a 3-bit
multiplier and a 20-bit second time.  The code tries to use the
original multiplier which is 4 as the second count is still 300 seconds
by default.

As the 20-bit number is now too large for practical use there is an option
to interpret it as microseconds instead of seconds.

Fixes: 2c119d99 ("net: dsa: microchip: add the support for set_ageing_time")
Signed-off-by: default avatarTristram Ha <tristram.ha@microchip.com>
Reviewed-by: default avatarAndrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20241218020224.70590-3-Tristram.Ha@microchip.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 262bfba8

drivers/net/dsa/microchip/lan937x_main.c

+59 −3
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Microchip LAN937X switch driver main logic

 * Copyright (C) 2019-2022 Microchip Technology Inc.

 * Copyright (C) 2019-2024 Microchip Technology Inc.

 */

#include <linux/kernel.h>

#include <linux/module.h>
@@ -461,10 +461,66 @@ int lan937x_change_mtu(struct ksz_device *dev, int port, int new_mtu) 


int lan937x_set_ageing_time(struct ksz_device *dev, unsigned int msecs)

{

	u32 secs = msecs / 1000;

	u32 value;

	u8 data, mult, value8;

	bool in_msec = false;

	u32 max_val, value;

	u32 secs = msecs;

	int ret;



#define MAX_TIMER_VAL	((1 << 20) - 1)



	/* The aging timer comprises a 3-bit multiplier and a 20-bit second

	 * value.  Either of them cannot be zero.  The maximum timer is then

	 * 7 * 1048575 = 7340025 seconds.  As this value is too large for

	 * practical use it can be interpreted as microseconds, making the

	 * maximum timer 7340 seconds with finer control.  This allows for

	 * maximum 122 minutes compared to 29 minutes in KSZ9477 switch.

	 */

	if (msecs % 1000)

		in_msec = true;

	else

		secs /= 1000;

	if (!secs)

		secs = 1;



	/* Return error if too large. */

	else if (secs > 7 * MAX_TIMER_VAL)

		return -EINVAL;



	/* Configure how to interpret the number value. */

	ret = ksz_rmw8(dev, REG_SW_LUE_CTRL_2, SW_AGE_CNT_IN_MICROSEC,

		       in_msec ? SW_AGE_CNT_IN_MICROSEC : 0);

	if (ret < 0)

		return ret;



	ret = ksz_read8(dev, REG_SW_LUE_CTRL_0, &value8);

	if (ret < 0)

		return ret;



	/* Check whether there is need to update the multiplier. */

	mult = FIELD_GET(SW_AGE_CNT_M, value8);

	max_val = MAX_TIMER_VAL;

	if (mult > 0) {

		/* Try to use the same multiplier already in the register as

		 * the hardware default uses multiplier 4 and 75 seconds for

		 * 300 seconds.

		 */

		max_val = DIV_ROUND_UP(secs, mult);

		if (max_val > MAX_TIMER_VAL || max_val * mult != secs)

			max_val = MAX_TIMER_VAL;

	}



	data = DIV_ROUND_UP(secs, max_val);

	if (mult != data) {

		value8 &= ~SW_AGE_CNT_M;

		value8 |= FIELD_PREP(SW_AGE_CNT_M, data);

		ret = ksz_write8(dev, REG_SW_LUE_CTRL_0, value8);

		if (ret < 0)

			return ret;

	}



	secs = DIV_ROUND_UP(secs, data);



	value = FIELD_GET(SW_AGE_PERIOD_7_0_M, secs);



	ret = ksz_write8(dev, REG_SW_AGE_PERIOD__1, value);

drivers/net/dsa/microchip/lan937x_reg.h

+6 −3
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

/* Microchip LAN937X switch register definitions

 * Copyright (C) 2019-2021 Microchip Technology Inc.

 * Copyright (C) 2019-2024 Microchip Technology Inc.

 */

#ifndef __LAN937X_REG_H

#define __LAN937X_REG_H
@@ -56,8 +56,7 @@ 


#define SW_VLAN_ENABLE			BIT(7)

#define SW_DROP_INVALID_VID		BIT(6)

#define SW_AGE_CNT_M			0x7

#define SW_AGE_CNT_S			3

#define SW_AGE_CNT_M			GENMASK(5, 3)

#define SW_RESV_MCAST_ENABLE		BIT(2)



#define REG_SW_LUE_CTRL_1		0x0311
@@ -70,6 +69,10 @@ 
#define SW_FAST_AGING			BIT(1)

#define SW_LINK_AUTO_AGING		BIT(0)



#define REG_SW_LUE_CTRL_2		0x0312



#define SW_AGE_CNT_IN_MICROSEC		BIT(7)



#define REG_SW_AGE_PERIOD__1		0x0313

#define SW_AGE_PERIOD_7_0_M		GENMASK(7, 0)