linux-kernel - Re: [PATCH v3 3/3] serial: sc16is7xx: add support for EXAR XR20M1172 UART

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Date: Thu, 18 Apr 2024 20:54:00 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Konstantin Pugin <rilian.la.te@...ru>
Cc: Konstantin Pugin <ria.freelander@...il.com>,
	Vladimir Zapolskiy <vz@...ia.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jirislaby@...nel.org>,
	Hugo Villeneuve <hvilleneuve@...onoff.com>,
	Lech Perczak <lech.perczak@...lingroup.com>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org,
	linux-serial@...r.kernel.org
Subject: Re: [PATCH v3 3/3] serial: sc16is7xx: add support for EXAR XR20M1172
 UART

On Thu, Apr 18, 2024 at 08:06:07PM +0300, Konstantin Pugin wrote:
> From: Konstantin Pugin <ria.freelander@...il.com>
> 
> XR20M1172 register set is mostly compatible with SC16IS762, but it has
> a support for additional division rates of UART with special DLD register.
> So, add handling this register by appropriate devicetree bindings.

..

>  /* Special Register set: Only if ((LCR[7] == 1) && (LCR != 0xBF)) */
>  #define SC16IS7XX_DLL_REG		(0x00) /* Divisor Latch Low */
>  #define SC16IS7XX_DLH_REG		(0x01) /* Divisor Latch High */
> +#define XR20M117X_DLD_REG		(0x02) /* Divisor Fractional Register (only on EXAR chips) */

The comment in the parentheses is not needed anymore as it's implied by
the namespace.

..

> +#define XR20M117X_DLD_16X		0
> +#define XR20M117X_DLD_DIV(m)	((m) & GENMASK(3, 0))

Seems like one too little TABs in between.

> +#define XR20M117X_DLD_8X		BIT(4)
> +#define XR20M117X_DLD_4X		BIT(5)

..

>  	char	name[10];
>  	int	nr_gpio;
>  	int	nr_uart;

> +	bool has_dld;

Not needed. See below.

..

> +	bool has_dld = s->devtype->has_dld;

So, you can check against devtype itself:

	s->devtype == &xr20m1172_devtype;

> +static const struct sc16is7xx_devtype = {

..

> +	if (has_dld && DIV_ROUND_CLOSEST(clk, baud) < 16)
> +		divisor = 1 << (fls(DIV_ROUND_CLOSEST(clk, baud)) - 1);

BIT() ?

-- 
With Best Regards,
Andy Shevchenko