netdev - Re: [PATCH v3 3/7] i2c: Add Nuvoton NCT6694 I2C support

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Message-ID: <qe7rucm65tixgnlendfdlr6iemrvs2ecun7odlbl3csofj7qjj@sl6vypb66awz>
Date: Thu, 26 Dec 2024 01:43:10 +0100
From: Andi Shyti <andi.shyti@...nel.org>
To: Ming Yu <a0282524688@...il.com>
Cc: tmyu0@...oton.com, lee@...nel.org, linus.walleij@...aro.org, 
	brgl@...ev.pl, mkl@...gutronix.de, mailhol.vincent@...adoo.fr, 
	andrew+netdev@...n.ch, davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org, 
	pabeni@...hat.com, wim@...ux-watchdog.org, linux@...ck-us.net, jdelvare@...e.com, 
	alexandre.belloni@...tlin.com, linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org, 
	linux-i2c@...r.kernel.org, linux-can@...r.kernel.org, netdev@...r.kernel.org, 
	linux-watchdog@...r.kernel.org, linux-hwmon@...r.kernel.org, linux-rtc@...r.kernel.org
Subject: Re: [PATCH v3 3/7] i2c: Add Nuvoton NCT6694 I2C support

Hi Ming,

> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Nuvoton NCT6694 I2C adapter driver based on USB interface.
> + *
> + * Copyright (C) 2024 Nuvoton Technology Corp.
> + */
> +
> +#include <linux/i2c.h>
> +#include <linux/kernel.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/nct6694.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +
> +/* Host interface */

What does it mean "Host interface"?

> +#define NCT6694_I2C_MOD		0x03
> +
> +/* Message Channel*/
> +/* Command 00h */

This comments are meaningless, either make them clearer or remove
them.

> +#define NCT6694_I2C_CMD0_OFFSET	0x0000	/* OFFSET = SEL|CMD */

I find this comment quite meaningless. Can you please make it
clearer?

> +#define NCT6694_I2C_CMD0_LEN	0x90
> +
> +enum i2c_baudrate {
> +	I2C_BR_25K = 0,
> +	I2C_BR_50K,
> +	I2C_BR_100K,
> +	I2C_BR_200K,
> +	I2C_BR_400K,
> +	I2C_BR_800K,
> +	I2C_BR_1M
> +};
> +
> +struct __packed nct6694_i2c_cmd0 {
> +	u8 port;
> +	u8 br;
> +	u8 addr;
> +	u8 w_cnt;
> +	u8 r_cnt;
> +	u8 rsv[11];
> +	u8 write_data[0x40];
> +	u8 read_data[0x40];
> +};
> +
> +struct nct6694_i2c_data {
> +	struct nct6694 *nct6694;
> +	struct i2c_adapter adapter;
> +	unsigned char *xmit_buf;

why isn't this a nct6694_i2c_cmd0 type?

> +	unsigned char port;
> +	unsigned char br;
> +};
> +
> +static int nct6694_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
> +{
> +	struct nct6694_i2c_data *data = adap->algo_data;
> +	struct nct6694_i2c_cmd0 *cmd = (struct nct6694_i2c_cmd0 *)data->xmit_buf;
> +	int ret, i;
> +
> +	for (i = 0; i < num ; i++) {
> +		struct i2c_msg *msg_temp = &msgs[i];
> +
> +		memset(data->xmit_buf, 0, sizeof(struct nct6694_i2c_cmd0));
> +
> +		if (msg_temp->len > 64)
> +			return -EPROTO;
> +		cmd->port = data->port;
> +		cmd->br = data->br;
> +		cmd->addr = i2c_8bit_addr_from_msg(msg_temp);
> +		if (msg_temp->flags & I2C_M_RD) {
> +			cmd->r_cnt = msg_temp->len;
> +			ret = nct6694_write_msg(data->nct6694, NCT6694_I2C_MOD,
> +						NCT6694_I2C_CMD0_OFFSET,
> +						NCT6694_I2C_CMD0_LEN,
> +						cmd);
> +			if (ret < 0)
> +				return 0;

why not return ret?

> +
> +			memcpy(msg_temp->buf, cmd->read_data, msg_temp->len);
> +		} else {
> +			cmd->w_cnt = msg_temp->len;
> +			memcpy(cmd->write_data, msg_temp->buf, msg_temp->len);
> +			ret = nct6694_write_msg(data->nct6694, NCT6694_I2C_MOD,
> +						NCT6694_I2C_CMD0_OFFSET,
> +						NCT6694_I2C_CMD0_LEN,
> +						cmd);
> +			if (ret < 0)
> +				return 0;
> +		}
> +	}
> +
> +	return num;
> +}
> +
> +static u32 nct6694_func(struct i2c_adapter *adapter)
> +{
> +	return (I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL);

parenthesis are not needed.

> +}

...

> +static struct platform_driver nct6694_i2c_driver = {
> +	.driver = {
> +		.name	= "nct6694-i2c",
> +	},
> +	.probe		= nct6694_i2c_probe,
> +	.remove		= nct6694_i2c_remove,
> +};
> +
> +module_platform_driver(nct6694_i2c_driver);

what I meant in v1 is to try using module_auxiliary_driver().
Check, e.g., i2c-ljca.c or i2c-keba.c.

Andi

> +MODULE_DESCRIPTION("USB-I2C adapter driver for NCT6694");
> +MODULE_AUTHOR("Ming Yu <tmyu0@...oton.com>");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:nct6694-i2c");
> -- 
> 2.34.1
>