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Date: Wed, 13 Jan 2021 10:33:39 +0100
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: Vincent Mailhol <mailhol.vincent@...adoo.fr>,
linux-can@...r.kernel.org
Cc: Arunachalam Santhanam <arunachalam.santhanam@...bosch.com>,
Wolfgang Grandegger <wg@...ndegger.com>,
"David S . Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Jimmy Assarsson <extja@...ser.com>,
Masahiro Yamada <masahiroy@...nel.org>,
"open list : NETWORKING DRIVERS" <netdev@...r.kernel.org>
Subject: Re: [PATCH v10 1/1] can: usb: etas_es58X: add support for ETAS ES58X
CAN USB interfaces
On 1/12/21 2:05 PM, Vincent Mailhol wrote:
> This driver supports the ES581.4, ES582.1 and ES584.1 interfaces from
> ETAS GmbH (https://www.etas.com/en/products/es58x.php).
>
> Co-developed-by: Arunachalam Santhanam <arunachalam.santhanam@...bosch.com>
> Signed-off-by: Arunachalam Santhanam <arunachalam.santhanam@...bosch.com>
> Signed-off-by: Vincent Mailhol <mailhol.vincent@...adoo.fr>
[...]
> diff --git a/drivers/net/can/usb/etas_es58x/es58x_core.c b/drivers/net/can/usb/etas_es58x/es58x_core.c
> new file mode 100644
> index 000000000000..30692d78d8e6
> --- /dev/null
> +++ b/drivers/net/can/usb/etas_es58x/es58x_core.c
> @@ -0,0 +1,2589 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +/* Driver for ETAS GmbH ES58X USB CAN(-FD) Bus Interfaces.
> + *
> + * File es58x_core.c: Core logic to manage the network devices and the
> + * USB interface.
> + *
> + * Copyright (C) 2019 Robert Bosch Engineering and Business
> + * Solutions. All rights reserved.
> + * Copyright (C) 2020 ETAS K.K.. All rights reserved.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/moduleparam.h>
> +#include <linux/usb.h>
> +#include <linux/crc16.h>
> +#include <linux/spinlock.h>
> +#include <asm/unaligned.h>
> +
> +#include "es58x_core.h"
> +
> +#define DRV_VERSION "1.00"
> +MODULE_AUTHOR("Mailhol Vincent <mailhol.vincent@...adoo.fr>");
> +MODULE_AUTHOR("Arunachalam Santhanam <arunachalam.santhanam@...bosch.com>");
> +MODULE_DESCRIPTION("Socket CAN driver for ETAS ES58X USB adapters");
> +MODULE_VERSION(DRV_VERSION);
> +MODULE_LICENSE("GPL v2");
> +
> +/* Vendor and product id */
> +#define ES58X_MODULE_NAME "etas_es58x"
> +#define ES58X_VENDOR_ID 0x108C
> +#define ES581_4_PRODUCT_ID 0x0159
> +#define ES582_1_PRODUCT_ID 0x0168
> +#define ES584_1_PRODUCT_ID 0x0169
> +
> +/* Table of devices which work with this driver */
> +static const struct usb_device_id es58x_id_table[] = {
> + {USB_DEVICE(ES58X_VENDOR_ID, ES581_4_PRODUCT_ID)},
> + {USB_DEVICE(ES58X_VENDOR_ID, ES582_1_PRODUCT_ID)},
> + {USB_DEVICE(ES58X_VENDOR_ID, ES584_1_PRODUCT_ID)},
> + {} /* Terminating entry */
> +};
> +
> +MODULE_DEVICE_TABLE(usb, es58x_id_table);
> +
> +#define es58x_print_hex_dump(buf, len) \
> + print_hex_dump(KERN_DEBUG, \
> + ES58X_MODULE_NAME " " __stringify(buf) ": ", \
> + DUMP_PREFIX_NONE, 16, 1, buf, len, false)
> +
> +#define es58x_print_hex_dump_debug(buf, len) \
> + print_hex_dump_debug(ES58X_MODULE_NAME " " __stringify(buf) ": ",\
> + DUMP_PREFIX_NONE, 16, 1, buf, len, false)
> +
> +/* The last two bytes of an ES58X command is a CRC16. The first two
> + * bytes (the start of frame) are skipped and the CRC calculation
> + * starts on the third byte.
> + */
> +#define ES58X_CRC_CALC_OFFSET 2
> +
> +/**
> + * es58x_calculate_crc() - Compute the crc16 of a given URB.
> + * @urb_cmd: The URB command for which we want to calculate the CRC.
> + * @urb_len: Length of @urb_cmd. Must be at least bigger than 4
> + * (ES58X_CRC_CALC_OFFSET + sizeof(crc))
> + *
> + * Return: crc16 value.
> + */
> +static u16 es58x_calculate_crc(const union es58x_urb_cmd *urb_cmd, u16 urb_len)
> +{
> + u16 crc;
> + ssize_t len = urb_len - ES58X_CRC_CALC_OFFSET - sizeof(crc);
> +
> + WARN_ON(len < 0);
Is it possible to ensure earlier, that the urbs are of correct length?
> + crc = crc16(0, &urb_cmd->raw_cmd[ES58X_CRC_CALC_OFFSET], len);
> + return crc;
> +}
[...]
> +/**
> + * struct es58x_priv - All information specific to a CAN channel.
> + * @can: struct can_priv must be the first member (Socket CAN relies
> + * on the fact that function netdev_priv() returns a pointer to
> + * a struct can_priv).
> + * @es58x_dev: pointer to the corresponding ES58X device.
> + * @tx_urb: Used as a buffer to concatenate the TX messages and to do
> + * a bulk send. Please refer to es58x_start_xmit() for more
> + * details.
> + * @echo_skb_spinlock: Spinlock to protect the access to the echo skb
> + * FIFO.
> + * @current_packet_idx: Keeps track of the packet indexes.
> + * @echo_skb_tail_idx: beginning of the echo skb FIFO, i.e. index of
> + * the first element.
> + * @echo_skb_head_idx: end of the echo skb FIFO plus one, i.e. first
> + * free index.
> + * @num_echo_skb: actual number of elements in the FIFO. Thus, the end
> + * of the FIFO is echo_skb_head = (echo_skb_tail_idx +
> + * num_echo_skb) % can.echo_skb_max.
> + * @tx_total_frame_len: sum, in bytes, of the length of each of the
> + * CAN messages contained in @tx_urb. To be used as an input of
> + * netdev_sent_queue() for BQL.
> + * @tx_can_msg_cnt: Number of messages in @tx_urb.
> + * @tx_can_msg_is_fd: false: all messages in @tx_urb are Classical
> + * CAN, true: all messages in @tx_urb are CAN FD. Rationale:
> + * ES58X FD devices do not allow to mix Classical CAN and FD CAN
> + * frames in one single bulk transmission.
> + * @err_passive_before_rtx_success: The ES58X device might enter in a
> + * state in which it keeps alternating between error passive
> + * and active state. This counter keeps track of the number of
> + * error passive and if it gets bigger than
> + * ES58X_CONSECUTIVE_ERR_PASSIVE_MAX, es58x_rx_err_msg() will
> + * force the status to bus-off.
> + * @channel_idx: Channel index, starts at zero.
> + */
> +struct es58x_priv {
> + struct can_priv can;
> + struct es58x_device *es58x_dev;
> + struct urb *tx_urb;
> +
> + spinlock_t echo_skb_spinlock; /* Comments: c.f. supra */
> + u32 current_packet_idx;
> + u16 echo_skb_tail_idx;
> + u16 echo_skb_head_idx;
> + u16 num_echo_skb;
Can you explain me how the tx-path works, especially why you need the
current_packet_idx.
In the mcp251xfd driver, the number of TX buffers is a power of two, that makes
things easier. tx_heads % len points to the next buffer to be filled, tx_tail %
len points to the next buffer to be completed. tx_head - tx_tail is the fill
level of the FIFO. This works without spinlocks.
> +
> + u16 tx_total_frame_len;
> + u8 tx_can_msg_cnt;
> + bool tx_can_msg_is_fd;
> +
> + u8 err_passive_before_rtx_success;
> +
> + u8 channel_idx;
> +};
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Embedded Linux | https://www.pengutronix.de |
Vertretung West/Dortmund | Phone: +49-231-2826-924 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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