linux-kernel - Re: [PATCH v5 2/3] i2c: at91: split driver into core and master file

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Message-ID: <20190225103444.GR9224@smile.fi.intel.com>
Date:   Mon, 25 Feb 2019 12:34:44 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Ludovic Desroches <ludovic.desroches@...rochip.com>
Cc:     linux-i2c@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        me@....yt, nicolas.ferre@...rochip.com,
        alexandre.belloni@...tlin.com, linux-kernel@...r.kernel.org,
        wsa@...-dreams.de
Subject: Re: [PATCH v5 2/3] i2c: at91: split driver into core and master file

On Fri, Feb 22, 2019 at 10:25:21AM +0100, Ludovic Desroches wrote:
> From: Juergen Fitschen <me@....yt>
> 
> The single file i2c-at91.c has been split into core code (i2c-at91-core.c)
> and master mode specific code (i2c-at91-master.c). This should enhance
> maintainability and reduce ifdeffery for slave mode related code.
> 
> The code itself hasn't been touched. Shared functions only had to be made
> non-static. Furthermore, includes have been cleaned up.

Since it's a split of existing code, consider my comments as a way to improve
it afterwards.

> +static struct at91_twi_pdata *at91_twi_get_driver_data(
> +					struct platform_device *pdev)
> +{
> +	if (pdev->dev.of_node) {
> +		const struct of_device_id *match;
> +		match = of_match_node(atmel_twi_dt_ids, pdev->dev.of_node);
> +		if (!match)
> +			return NULL;
> +		return (struct at91_twi_pdata *)match->data;
> +	}
> +	return (struct at91_twi_pdata *) platform_get_device_id(pdev)->driver_data;



One may do the following instead:
	struct at91_twi_pdata *data;

	data = device_get_match_data(&pdev->dev);
	if (data)
		return data;
	return ...

And if you ever will switch old platform to somelike unified interface for
device properties, I would recommend to use device_property_* instead of
of_property_* and so on.

> +}

> +#include <linux/clk.h>
> +#include <linux/completion.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/dmaengine.h>
> +#include <linux/i2c.h>
> +#include <linux/platform_data/dma-atmel.h>
> +#include <linux/platform_device.h>

Are all those anyhow in use in this header file?

> +#define AT91_I2C_TIMEOUT	msecs_to_jiffies(100)	/* transfer timeout */

Wouldn't be better to use _MS here and call actual conversion whenever it's
needed?

> +#define AT91_I2C_DMA_THRESHOLD	8			/* enable DMA if transfer size is bigger than this threshold */

> +#define AUTOSUSPEND_TIMEOUT		2000

_MS ?

> +#define	AT91_TWI_SR		0x0020	/* Status Register */
> +#define	AT91_TWI_TXCOMP		BIT(0)	/* Transmission Complete */
> +#define	AT91_TWI_RXRDY		BIT(1)	/* Receive Holding Register Ready */
> +#define	AT91_TWI_TXRDY		BIT(2)	/* Transmit Holding Register Ready */
> +#define	AT91_TWI_OVRE		BIT(6)	/* Overrun Error */
> +#define	AT91_TWI_UNRE		BIT(7)	/* Underrun Error */
> +#define	AT91_TWI_NACK		BIT(8)	/* Not Acknowledged */
> +#define	AT91_TWI_LOCK		BIT(23) /* TWI Lock due to Frame Errors */
> +
> +#define	AT91_TWI_INT_MASK \
> +	(AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY | AT91_TWI_NACK)
> +
> +#define	AT91_TWI_IER		0x0024	/* Interrupt Enable Register */
> +#define	AT91_TWI_IDR		0x0028	/* Interrupt Disable Register */
> +#define	AT91_TWI_IMR		0x002c	/* Interrupt Mask Register */
> +#define	AT91_TWI_RHR		0x0030	/* Receive Holding Register */
> +#define	AT91_TWI_THR		0x0034	/* Transmit Holding Register */
> +
> +#define	AT91_TWI_ACR		0x0040	/* Alternative Command Register */
> +#define	AT91_TWI_ACR_DATAL(len)	((len) & 0xff)
> +#define	AT91_TWI_ACR_DIR	BIT(8)
> +
> +#define	AT91_TWI_FMR		0x0050	/* FIFO Mode Register */
> +#define	AT91_TWI_FMR_TXRDYM(mode)	(((mode) & 0x3) << 0)

> +#define	AT91_TWI_FMR_TXRDYM_MASK	(0x3 << 0)

GENMASK() ?

> +#define	AT91_TWI_FMR_RXRDYM(mode)	(((mode) & 0x3) << 4)

> +#define	AT91_TWI_FMR_RXRDYM_MASK	(0x3 << 4)

Ditto.

-- 
With Best Regards,
Andy Shevchenko