Subject: Re: [PATCH v3 07/42] soc: Add SoC driver for Cirrus ep93xx

From: Andy Shevchenko <[email-masked]>
Date: Fri, 21 Jul 2023 17:13:55 +0300

On Thu, Jul 20, 2023 at 02:29:07PM +0300, Nikita Shubin via B4 Relay wrote:
> From: Nikita Shubin <[email-masked]>
> 
> This adds an SoC driver for the ep93xx. Currently there
> is only one thing not fitting into any other framework,
> and that is the swlock setting.
> 
> It's used for clock settings and restart.

> +#include <linux/clk-provider.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/of.h>
> +#include <linux/regmap.h>
> +#include <linux/slab.h>
> +#include <linux/sys_soc.h>
> +#include <linux/soc/cirrus/ep93xx.h>

...

> +#define EP93XX_SYSCON_SYSCFG_REV_MASK	0xf0000000

GENMASK() (you will need bits.h, and looking below you seem missed it anyway)

...

> +	spin_lock_irqsave(&ep93xx_swlock, flags);
> +
> +	regmap_read(map, EP93XX_SYSCON_DEVCFG, &val);
> +	val &= ~clear_bits;
> +	val |= set_bits;
> +	regmap_write(map, EP93XX_SYSCON_SWLOCK, EP93XX_SWLOCK_MAGICK);
> +	regmap_write(map, EP93XX_SYSCON_DEVCFG, val);

Is this sequence a must?
I.o.w. can you first supply magic and then update devcfg?

> +	spin_unlock_irqrestore(&ep93xx_swlock, flags);

...

> +void ep93xx_swlocked_update_bits(struct regmap *map, unsigned int reg,
> +				 unsigned int mask, unsigned int val)
> +{

Same Q as above.

> +}

...

> +	int rev = ep93xx_chip_revision(map);
> +
> +	switch (rev) {

	switch(ep93xx_chip_revision(map))

?

> +	case EP93XX_CHIP_REV_D0:
> +		return "D0";
> +	case EP93XX_CHIP_REV_D1:
> +		return "D1";
> +	case EP93XX_CHIP_REV_E0:
> +		return "E0";
> +	case EP93XX_CHIP_REV_E1:
> +		return "E1";
> +	case EP93XX_CHIP_REV_E2:
> +		return "E2";
> +	default:
> +		return "unknown";
> +	}

...

> +static unsigned long __init calc_pll_rate(u64 rate, u32 config_word)
> +{
> +	rate *= ((config_word >> 11) & GENMASK(4, 0)) + 1;	/* X1FBD */
> +	rate *= ((config_word >> 5) & GENMASK(5, 0)) + 1;	/* X2FBD */
> +	do_div(rate, (config_word & GENMASK(4, 0)) + 1);	/* X2IPD */
> +	rate >>= ((config_word >> 16) & 3);			/* PS */

GENMASK()

> +	return rate;
> +}

...

> +	/* Multiplatform guard, only proceed on ep93xx */
> +	if (!of_machine_is_compatible("cirrus,ep9301"))
> +		return 0;

Why?

> +	map = syscon_regmap_lookup_by_compatible("cirrus,ep9301-syscon");
> +	if (IS_ERR(map))
> +		return PTR_ERR(map);

Is this not enough?

...

> +	if (!(value & EP93XX_SYSCON_CLKSET1_NBYP1))
> +		clk_pll1_rate = EP93XX_EXT_CLK_RATE;
> +	else
> +		clk_pll1_rate = calc_pll_rate(EP93XX_EXT_CLK_RATE, value);

Positive conditionals in if-else are easier to be read.

...

> +	clk_f_div = fclk_divisors[(value >> 25) & 0x7];
> +	clk_h_div = hclk_divisors[(value >> 20) & 0x7];
> +	clk_p_div = pclk_divisors[(value >> 18) & 0x3];

GENMASK() in all three?

...

> +	np = of_find_node_by_path("/");
> +	of_property_read_string(np, "model", &machine);
> +	if (machine)
> +		attrs->machine = kstrdup(machine, GFP_KERNEL);

No error check?

> +	of_node_put(np);

Looks like NIH of_flat_dt_get_machine_name(). Can you rather make use of it as
it's done, e.g., here arch/riscv/kernel/setup.c:251?

-- 
With Best Regards,
Andy Shevchenko