On Mon, Oct 25, 2021 at 12:42 PM Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
>
> The TPS68470 PMIC provides Clocks, GPIOs and Regulators. At present in
> the kernel the Regulators and Clocks are controlled by an OpRegion
> driver designed to work with power control methods defined in ACPI, but
> some platforms lack those methods, meaning drivers need to be able to
> consume the resources of these chips through the usual frameworks.
>
> This commit adds a driver for the clocks provided by the tps68470,
> and is designed to bind to the platform_device registered by the
> intel_skl_int3472 module.
...
> +/*
> + * The PLL is used to multiply the crystal oscillator
> + * frequency range of 3 MHz to 27 MHz by a programmable
> + * factor of F = (M/N)*(1/P) such that the output
> + * available at the HCLK_A or HCLK_B pins are in the range
> + * of 4 MHz to 64 MHz in increments of 0.1 MHz
Missed (grammatical) period.
> + *
> + * hclk_# = osc_in * (((plldiv*2)+320) / (xtaldiv+30)) * (1 / 2^postdiv)
> + *
> + * PLL_REF_CLK should be as close as possible to 100kHz
> + * PLL_REF_CLK = input clk / XTALDIV[7:0] + 30)
> + *
> + * PLL_VCO_CLK = (PLL_REF_CLK * (plldiv*2 + 320))
> + *
> + * BOOST should be as close as possible to 2Mhz
> + * BOOST = PLL_VCO_CLK / (BOOSTDIV[4:0] + 16) *
> + *
> + * BUCK should be as close as possible to 5.2Mhz
> + * BUCK = PLL_VCO_CLK / (BUCKDIV[3:0] + 5)
> + *
> + * osc_in xtaldiv plldiv postdiv hclk_#
> + * 20Mhz 170 32 1 19.2Mhz
> + * 20Mhz 170 40 1 20Mhz
> + * 20Mhz 170 80 1 24Mhz
> + *
Redundant empty line.
> + */
...
> + /* disable clock first */
Disable
first...
> + /* and then tri-state the clock outputs */
...and
...
> + for (i = 0; i < ARRAY_SIZE(clk_freqs); i++) {
> + diff = clk_freqs[i].freq - rate;
> + if (diff == 0)
> + return i;
> + diff = abs(diff);
This needs a comment why higher (lower) frequency is okay.
> + if (diff < best_diff) {
> + best_diff = diff;
> + best_idx = i;
> + }
> + }
...
> + if (pdata) {
> + ret = devm_clk_hw_register_clkdev(&pdev->dev,
> + &tps68470_clkdata->clkout_hw,
> + pdata->consumer_con_id,
> + pdata->consumer_dev_name);
if (ret)
return ret;
> + }
> +
> + return ret;
return 0;
--
With Best Regards,
Andy Shevchenko
