Commit a1439a5a authored by Marc Kleine-Budde's avatar Marc Kleine-Budde
Browse files

can: mcp251xfd: ram: add helper function for runtime ring size calculation 

This patch adds a helper function to calculate the ring configuration
of the controller based on various constraints, like available RAM,
size of RX and TX objects, CAN-mode, number of FIFOs and FIFO depth.

Link: https://lore.kernel.org/20220313083640.501791-3-mkl@pengutronix.de


Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
parent c47675b1

drivers/net/can/spi/mcp251xfd/Makefile

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@@ -6,6 +6,7 @@ mcp251xfd-objs := 
mcp251xfd-objs += mcp251xfd-chip-fifo.o

mcp251xfd-objs += mcp251xfd-core.o

mcp251xfd-objs += mcp251xfd-crc16.o

mcp251xfd-objs += mcp251xfd-ram.o

mcp251xfd-objs += mcp251xfd-regmap.o

mcp251xfd-objs += mcp251xfd-ring.o

mcp251xfd-objs += mcp251xfd-rx.o

drivers/net/can/spi/mcp251xfd/mcp251xfd-ram.c

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+97 −0
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// SPDX-License-Identifier: GPL-2.0

//

// mcp251xfd - Microchip MCP251xFD Family CAN controller driver

//

// Copyright (c) 2021, 2022 Pengutronix,

//               Marc Kleine-Budde <kernel@pengutronix.de>

//



#include "mcp251xfd-ram.h"



static inline u8 can_ram_clamp(const struct can_ram_config *config,

			       const struct can_ram_obj_config *obj,

			       u8 val)

{

	u8 max;



	max = min_t(u8, obj->max, obj->fifo_num * config->fifo_depth);

	return clamp(val, obj->min, max);

}



static u8

can_ram_rounddown_pow_of_two(const struct can_ram_config *config,

			     const struct can_ram_obj_config *obj, u8 val)

{

	u8 fifo_num = obj->fifo_num;

	u8 ret = 0, i;



	val = can_ram_clamp(config, obj, val);



	for (i = 0; i < fifo_num && val; i++) {

		u8 n;



		n = min_t(u8, rounddown_pow_of_two(val),

			  config->fifo_depth);



		/* skip small FIFOs */

		if (n < obj->fifo_depth_min)

			return ret;



		ret += n;

		val -= n;

	}



	return ret;

}



void can_ram_get_layout(struct can_ram_layout *layout,

			const struct can_ram_config *config,

			const struct ethtool_ringparam *ring,

			const bool fd_mode)

{

	u8 num_rx, num_tx;

	u16 ram_free;



	/* default CAN */



	num_tx = config->tx.def[fd_mode];

	num_tx = can_ram_rounddown_pow_of_two(config, &config->tx, num_tx);



	ram_free = config->size;

	ram_free -= config->tx.size[fd_mode] * num_tx;



	num_rx = ram_free / config->rx.size[fd_mode];



	layout->default_rx = can_ram_rounddown_pow_of_two(config, &config->rx, num_rx);

	layout->default_tx = num_tx;



	/* MAX CAN */



	ram_free = config->size;

	ram_free -= config->tx.size[fd_mode] * config->tx.min;

	num_rx = ram_free / config->rx.size[fd_mode];



	ram_free = config->size;

	ram_free -= config->rx.size[fd_mode] * config->rx.min;

	num_tx = ram_free / config->tx.size[fd_mode];



	layout->max_rx = can_ram_rounddown_pow_of_two(config, &config->rx, num_rx);

	layout->max_tx = can_ram_rounddown_pow_of_two(config, &config->tx, num_tx);



	/* cur CAN */



	if (ring) {

		num_rx = can_ram_rounddown_pow_of_two(config, &config->rx, ring->rx_pending);



		ram_free = config->size - config->rx.size[fd_mode] * num_rx;

		num_tx = ram_free / config->tx.size[fd_mode];

		num_tx = min_t(u8, ring->tx_pending, num_tx);

		num_tx = can_ram_rounddown_pow_of_two(config, &config->tx, num_tx);



		layout->cur_rx = num_rx;

		layout->cur_tx = num_tx;

	} else {

		layout->cur_rx = layout->default_rx;

		layout->cur_tx = layout->default_tx;

	}

}

drivers/net/can/spi/mcp251xfd/mcp251xfd-ram.h

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Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0

 *

 * mcp251xfd - Microchip MCP251xFD Family CAN controller driver

 *

 * Copyright (c) 2021, 2022 Pengutronix,

 *               Marc Kleine-Budde <kernel@pengutronix.de>

 */



#ifndef _MCP251XFD_RAM_H

#define _MCP251XFD_RAM_H



#include <linux/ethtool.h>



#define CAN_RAM_NUM_MAX (-1)



enum can_ram_mode {

	CAN_RAM_MODE_CAN,

	CAN_RAM_MODE_CANFD,

	__CAN_RAM_MODE_MAX

};



struct can_ram_obj_config {

	u8 size[__CAN_RAM_MODE_MAX];



	u8 def[__CAN_RAM_MODE_MAX];

	u8 min;

	u8 max;



	u8 fifo_num;

	u8 fifo_depth_min;

};



struct can_ram_config {

	const struct can_ram_obj_config rx;

	const struct can_ram_obj_config tx;



	u16 size;

	u8 fifo_depth;

};



struct can_ram_layout {

	u8 default_rx;

	u8 default_tx;



	u8 max_rx;

	u8 max_tx;



	u8 cur_rx;

	u8 cur_tx;

};



void can_ram_get_layout(struct can_ram_layout *layout,

			const struct can_ram_config *config,

			const struct ethtool_ringparam *ring,

			const bool fd_mode);



#endif