Re: [PATCH 08/12] clk: samsung: add clock controller driver for s3c2410, s3c2440 and s3c2442

Tomasz Figa
2014-02-09T19:34:36Z

Hi Heiko,

On 13.12.2013 14:01, Heiko Stübner wrote:
> This driver can handle the clock controllers of the socs mentioned above,
> as they share a common clock tree with only small differences.

[snip]

> diff --git a/drivers/clk/samsung/clk-s3c2410.c b/drivers/clk/samsung/clk-s3c2410.c
> new file mode 100644
> index 0000000..8358cad
> --- /dev/null
> +++ b/drivers/clk/samsung/clk-s3c2410.c

[snip]

> +static struct clk_div_table divslow_d[] = {
> + { .val = 0, .div = 1 },
> + { .val = 1, .div = 2 },
> + { .val = 2, .div = 4 },
> + { .val = 3, .div = 6 },
> + { .val = 4, .div = 8 },
> + { .val = 5, .div = 10 },
> + { .val = 6, .div = 12 },
> + { .val = 7, .div = 14 },
> + { .div = 0 },

nit: It might be just a matter of preference, but I'd say the more
common pattern is to define the last entry as:

{ /* sentinel */ },

It will be initialized to all-zeroes anyway, but the comment will tell
its purpose.

> +};
> +
> +struct samsung_div_clock s3c2410_common_dividers[] __initdata = {
> + DIV_T(0, "div_slow", "xti", CLKSLOW, 0, 3, divslow_d),
> + DIV(PCLK, "pclk", "hclk", CLKDIVN, 0, 1),
> +};

[snip]

> +static struct samsung_pll_rate_table pll_s3c2410_12mhz_tbl[] __initdata = {
> + /* sorted in descending order */
> + /* 2410A extras */
> + PLL_35XX_RATE(270000000, 127, 1, 1),
> + PLL_35XX_RATE(268000000, 126, 1, 1),
> + PLL_35XX_RATE(266000000, 125, 1, 1),
> + PLL_35XX_RATE(226000000, 105, 1, 1),
> + PLL_35XX_RATE(210000000, 132, 2, 1),
> + /* 2410 common */
> + PLL_35XX_RATE(203000000, 161, 3, 1),
> + PLL_35XX_RATE(192000000, 88, 1, 1),
> + PLL_35XX_RATE(186000000, 85, 1, 1),
> + PLL_35XX_RATE(180000000, 82, 1, 1),
> + PLL_35XX_RATE(170000000, 77, 1, 1),
> + PLL_35XX_RATE(158000000, 71, 1, 1),
> + PLL_35XX_RATE(152000000, 68, 1, 1),
> + PLL_35XX_RATE(147000000, 90, 2, 1),
> + PLL_35XX_RATE(135000000, 82, 2, 1),
> + PLL_35XX_RATE(124000000, 116, 1, 2),
> + PLL_35XX_RATE(118000000, 150, 2, 2),
> + PLL_35XX_RATE(113000000, 105, 1, 2),
> + PLL_35XX_RATE(101000000, 127, 2, 2),
> + PLL_35XX_RATE(90000000, 112, 2, 2),
> + PLL_35XX_RATE(85000000, 105, 2, 2),
> + PLL_35XX_RATE(79000000, 71, 1, 2),
> + PLL_35XX_RATE(68000000, 82, 2, 2),
> + PLL_35XX_RATE(56000000, 142, 2, 3),
> + PLL_35XX_RATE(48000000, 120, 2, 3),
> + PLL_35XX_RATE(51000000, 161, 3, 3),
> + PLL_35XX_RATE(45000000, 82, 1, 3),
> + PLL_35XX_RATE(34000000, 82, 2, 3),
> + { },

nit: The same comment about the sentinel as above.

> +};
> +
> +static struct samsung_pll_clock s3c2410_plls[] __initdata = {
> + [mpll] = PLL(pll_s3c2410_mpll, MPLL, "mpll", "xti",
> + LOCKTIME, MPLLCON, NULL),
> + [upll] = PLL(pll_s3c2410_upll, UPLL, "upll", "xti",
> + LOCKTIME, UPLLCON, NULL),
> +};

[snip]

> +static struct samsung_pll_rate_table pll_s3c244x_12mhz_tbl[] __initdata = {
> + /* sorted in descending order */
> + PLL_35XX_RATE(400000000, 0x5c, 1, 1),
> + PLL_35XX_RATE(390000000, 0x7a, 2, 1),
> + PLL_35XX_RATE(380000000, 0x57, 1, 1),
> + PLL_35XX_RATE(370000000, 0xb1, 4, 1),
> + PLL_35XX_RATE(360000000, 0x70, 2, 1),
> + PLL_35XX_RATE(350000000, 0xa7, 4, 1),
> + PLL_35XX_RATE(340000000, 0x4d, 1, 1),
> + PLL_35XX_RATE(330000000, 0x66, 2, 1),
> + PLL_35XX_RATE(320000000, 0x98, 4, 1),
> + PLL_35XX_RATE(310000000, 0x93, 4, 1),
> + PLL_35XX_RATE(300000000, 0x75, 3, 1),
> + PLL_35XX_RATE(240000000, 0x70, 1, 2),
> + PLL_35XX_RATE(230000000, 0x6b, 1, 2),
> + PLL_35XX_RATE(220000000, 0x66, 1, 2),
> + PLL_35XX_RATE(210000000, 0x84, 2, 2),
> + PLL_35XX_RATE(200000000, 0x5c, 1, 2),
> + PLL_35XX_RATE(190000000, 0x57, 1, 2),
> + PLL_35XX_RATE(180000000, 0x70, 2, 2),
> + PLL_35XX_RATE(170000000, 0x4d, 1, 2),
> + PLL_35XX_RATE(160000000, 0x98, 4, 2),
> + PLL_35XX_RATE(150000000, 0x75, 3, 2),
> + PLL_35XX_RATE(120000000, 0x70, 1, 3),
> + PLL_35XX_RATE(110000000, 0x66, 1, 3),
> + PLL_35XX_RATE(100000000, 0x5c, 1, 3),
> + PLL_35XX_RATE(90000000, 0x70, 2, 3),
> + PLL_35XX_RATE(80000000, 0x98, 4, 3),
> + PLL_35XX_RATE(75000000, 0x75, 3, 3),

Hmm, don't you need a sentinel here?

> +};
> +
> +static struct samsung_pll_clock s3c244x_common_plls[] __initdata = {
> + [mpll] = PLL(pll_s3c2440_mpll, MPLL, "mpll", "xti",
> + LOCKTIME, MPLLCON, NULL),
> + [upll] = PLL(pll_s3c2410_upll, UPLL, "upll", "xti",
> + LOCKTIME, UPLLCON, NULL),
> +};
> +
> +PNAME(hclk_p) = { "fclk", "div_hclk_2", "div_hclk_4", "div_hclk_3" };
> +PNAME(armclk_p) = { "fclk", "hclk" };
> +
> +struct samsung_mux_clock s3c244x_common_muxes[] __initdata = {
> + MUX(HCLK, "hclk", hclk_p, CLKDIVN, 1, 2),
> + MUX(ARMCLK, "armclk", armclk_p, CAMDIVN, 12, 1),
> +};
> +
> +struct samsung_fixed_factor_clock s3c244x_common_ffactor[] __initdata = {
> + FFACTOR(0, "div_hclk_2", "fclk", 1, 2, 0),
> + FFACTOR(0, "ff_cam", "div_cam", 2, 1, CLK_SET_RATE_PARENT),
> +};
> +
> +static struct clk_div_table div_hclk_4_d[] = {
> + { .val = 0, .div = 4 },
> + { .val = 1, .div = 8 },

Missing sentinel?

> +};
> +
> +static struct clk_div_table div_hclk_3_d[] = {
> + { .val = 0, .div = 3 },
> + { .val = 1, .div = 6 },

Ditto.

> +};
> +
> +struct samsung_div_clock s3c244x_common_dividers[] __initdata = {
> + DIV(UCLK, "uclk", "upll", CLKDIVN, 3, 1),
> + DIV(0, "div_hclk", "fclk", CLKDIVN, 1, 1),
> + DIV_T(0, "div_hclk_4", "fclk", CAMDIVN, 9, 1, div_hclk_4_d),
> + DIV_T(0, "div_hclk_3", "fclk", CAMDIVN, 8, 1, div_hclk_3_d),
> + DIV(0, "div_cam", "upll", CAMDIVN, 0, 3),
> +};

[snip]

> +/*
> + * fixed rate clocks generated outside the soc
> + * Only necessary until the devicetree-move is complete
> + */
> +struct samsung_fixed_rate_clock s3c2410_common_frate_clks[] __initdata = {
> + FRATE(XTI, "xti", NULL, CLK_IS_ROOT, 0),

Do you need to assign this clock an ID? When DT is used, it's defined as
a separate clock provider using fixed clock bindings, so it is not
provided by this driver.

> +};
> +
> +static void __init s3c2410_common_clk_register_fixed_ext(unsigned long xti_f)
> +{
> + struct samsung_clock_alias xti_alias = ALIAS(XTI, NULL, "xtal");
> +
> + s3c2410_common_frate_clks[0].fixed_rate = xti_f;
> + samsung_clk_register_fixed_rate(s3c2410_common_frate_clks,
> + ARRAY_SIZE(s3c2410_common_frate_clks));
> +
> + samsung_clk_register_alias(&xti_alias, 1);
> +}

[snip]

> diff --git a/include/dt-bindings/clock/samsung,s3c2410-clock.h b/include/dt-bindings/clock/samsung,s3c2410-clock.h
> new file mode 100644
> index 0000000..66c278f
> --- /dev/null
> +++ b/include/dt-bindings/clock/samsung,s3c2410-clock.h

I know this is nitpiccking, but I'd say that the name of this file could
be made a simple "s3c2410.h", as it's already located in "clock"
directory and "s3c2410" is specific enough to not add "samsung" prefix.

At the time of writing the s3c64xx CCF driver I went for full compatible
string as the file name, but at that time there was just a few DT
binding headers available and so no widely used naming convention. Now
looking at file names, other platforms seem to use just a simple name
and we decided to do the same for Exynos as well, so I think s3c24xx
should follow the same.

Best regards,
Tomasz