Re: [PATCH 2/2] clk: X1000: Add support for calculat REFCLK of USB PHY.

Paul Cercueil
2020-06-29T20:46:34Z

Hi Zhou,

Le lun. 29 juin 2020 à 0:18, Zhou Yanjie <zhouyanjie@wanyeetech.com> a
écrit :
> Hi Paul,
>
> 在 2020/6/27 上午1:36, Paul Cercueil 写道:
>> Hi Zhou,
>>
>> Le sam. 27 juin 2020 à 0:48, 周琰杰 (Zhou Yanjie)
>> \x7f<zhouyanjie@wanyeetech.com> a écrit :
>>> Add new functions to "x1000_otg_phy_ops" to calculat the rate of
>>> REFCLK,
>>> which is needed by USB PHY in the Ingenic X1000 SoC.
>>>
>>> Tested-by: 周正 (Zhou Zheng) <sernia.zhou@foxmail.com>
>>> Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
>>> ---
>>> drivers/clk/ingenic/x1000-cgu.c | 113
>>> \x7f\x7f++++++++++++++++++++++++++++++++++++++++
>>> 1 file changed, 113 insertions(+)
>>>
>>> diff --git a/drivers/clk/ingenic/x1000-cgu.c
>>> \x7f\x7fb/drivers/clk/ingenic/x1000-cgu.c
>>> index 453f3323cb99..a61c16f98a11 100644
>>> --- a/drivers/clk/ingenic/x1000-cgu.c
>>> +++ b/drivers/clk/ingenic/x1000-cgu.c
>>> @@ -48,8 +48,114 @@
>>> #define USBPCR_SIDDQ BIT(21)
>>> #define USBPCR_OTG_DISABLE BIT(20)
>>>
>>> +/* bits within the USBPCR1 register */
>>> +#define USBPCR1_REFCLKSEL_SHIFT 26
>>> +#define USBPCR1_REFCLKSEL_MASK (0x3 << USBPCR1_REFCLKSEL_SHIFT)
>>> +#define USBPCR1_REFCLKSEL_CORE (0x2 << USBPCR1_REFCLKSEL_SHIFT)
>>> +#define USBPCR1_REFCLKDIV_SHIFT 24
>>> +#define USBPCR1_REFCLKDIV_MASK (0x3 << USBPCR1_REFCLKDIV_SHIFT)
>>> +#define USBPCR1_REFCLKDIV_48 (0x2 << USBPCR1_REFCLKDIV_SHIFT)
>>> +#define USBPCR1_REFCLKDIV_24 (0x1 << USBPCR1_REFCLKDIV_SHIFT)
>>> +#define USBPCR1_REFCLKDIV_12 (0x0 << USBPCR1_REFCLKDIV_SHIFT)
>>> +
>>> static struct ingenic_cgu *cgu;
>>>
>>> +static u8 x1000_otg_phy_get_parent(struct clk_hw *hw)
>>> +{
>>> + /* we only use CLKCORE, revisit if that ever changes */
>>> + return 0;
>>> +}
>>> +
>>> +static int x1000_otg_phy_set_parent(struct clk_hw *hw, u8 idx)
>>> +{
>>> + unsigned long flags;
>>> + u32 usbpcr1;
>>> +
>>> + if (idx > 0)
>>> + return -EINVAL;
>>> +
>>> + spin_lock_irqsave(&cgu->lock, flags);
>>> +
>>> + usbpcr1 = readl(cgu->base + CGU_REG_USBPCR1);
>>> + usbpcr1 &= ~USBPCR1_REFCLKSEL_MASK;
>>> + /* we only use CLKCORE */
>>> + usbpcr1 |= USBPCR1_REFCLKSEL_CORE;
>>> + writel(usbpcr1, cgu->base + CGU_REG_USBPCR1);
>>> +
>>> + spin_unlock_irqrestore(&cgu->lock, flags);
>>> + return 0;
>>> +}
>>
>> If you only support one parent, maybe set that bit in the
>> \x7fx1000_cgu_init(), then you can drop the get_parent/set_parent.
>>
>
> Sure.
>
>
>>> +
>>> +static unsigned long x1000_otg_phy_recalc_rate(struct clk_hw *hw,
>>> + unsigned long parent_rate)
>>> +{
>>> + u32 usbpcr1;
>>> + unsigned refclk_div;
>>> +
>>> + usbpcr1 = readl(cgu->base + CGU_REG_USBPCR1);
>>> + refclk_div = usbpcr1 & USBPCR1_REFCLKDIV_MASK;
>>> +
>>> + switch (refclk_div) {
>>> + case USBPCR1_REFCLKDIV_12:
>>> + return 12000000;
>>> +
>>> + case USBPCR1_REFCLKDIV_24:
>>> + return 24000000;
>>> +
>>> + case USBPCR1_REFCLKDIV_48:
>>> + return 48000000;
>>> + }
>>
>> On your setup, what frequency is configured for the "otg" clock? Is
>> it \x7f48 MHz?
>>
>> I believe CLKCORE is the OTG core's clock (aka "otg"), and I'm
>> pretty \x7fsure that these fields only represent CLKCORE/4, CLKCORE/2,
>> CLKCORE/1, \x7fbut the doc expects CLKCORE==48MHz.
>>
>
> This is the REFCLKDIV in USBPCR1 reg, it's for the usb phy, so it is
> not the otg clock. In X1000 and X1500 it is 24MHz, in JZ4780 it is
> 48MHz.

I know it is for the OTG PHY clock, what I'm saying is that the OTG PHY
clock is derived from CLKCORE which I believe is the "otg" clock.
Unless the clock represents a crystal, it is derived from another
clock, and as a result the clock rate should be computed from the
parent clock rate.

-Paul

>
>> In that case the "otg_phy" should be parented to "otg", and the rate
>> \x7fshould be computed according to the parent rate and the divider
>> \x7fconfigured.
>>
>>> +
>>> + BUG();
>>
>> Don't use BUG() - it pisses off Linus :)
>> And it's reserved for bugs that will take the whole system down, I
>> \x7fthink. Better use WARN().
>>
>
> Sure, I will change it in the next version.
>
> Thanks and best regards!
>
>
>> Cheers,
>> -Paul
>>
>>> + return parent_rate;
>>> +}
>>> +
>>> +static long x1000_otg_phy_round_rate(struct clk_hw *hw, unsigned
>>> \x7f\x7flong req_rate,
>>> + unsigned long *parent_rate)
>>> +{
>>> + if (req_rate < 18000000)
>>> + return 12000000;
>>> +
>>> + if (req_rate < 36000000)
>>> + return 24000000;
>>> +
>>> + return 48000000;
>>> +}
>>> +
>>> +static int x1000_otg_phy_set_rate(struct clk_hw *hw, unsigned long
>>> \x7f\x7freq_rate,
>>> + unsigned long parent_rate)
>>> +{
>>> + unsigned long flags;
>>> + u32 usbpcr1, div_bits;
>>> +
>>> + switch (req_rate) {
>>> + case 12000000:
>>> + div_bits = USBPCR1_REFCLKDIV_12;
>>> + break;
>>> +
>>> + case 24000000:
>>> + div_bits = USBPCR1_REFCLKDIV_24;
>>> + break;
>>> +
>>> + case 48000000:
>>> + div_bits = USBPCR1_REFCLKDIV_48;
>>> + break;
>>> +
>>> + default:
>>> + return -EINVAL;
>>> + }
>>> +
>>> + spin_lock_irqsave(&cgu->lock, flags);
>>> +
>>> + usbpcr1 = readl(cgu->base + CGU_REG_USBPCR1);
>>> + usbpcr1 &= ~USBPCR1_REFCLKDIV_MASK;
>>> + usbpcr1 |= div_bits;
>>> + writel(usbpcr1, cgu->base + CGU_REG_USBPCR1);
>>> +
>>> + spin_unlock_irqrestore(&cgu->lock, flags);
>>> + return 0;
>>> +}
>>> +
>>> static int x1000_usb_phy_enable(struct clk_hw *hw)
>>> {
>>> void __iomem *reg_opcr = cgu->base + CGU_REG_OPCR;
>>> @@ -80,6 +186,13 @@ static int x1000_usb_phy_is_enabled(struct
>>> clk_hw \x7f\x7f*hw)
>>> }
>>>
>>> static const struct clk_ops x1000_otg_phy_ops = {
>>> + .get_parent = x1000_otg_phy_get_parent,
>>> + .set_parent = x1000_otg_phy_set_parent,
>>> +
>>> + .recalc_rate = x1000_otg_phy_recalc_rate,
>>> + .round_rate = x1000_otg_phy_round_rate,
>>> + .set_rate = x1000_otg_phy_set_rate,
>>> +
>>> .enable = x1000_usb_phy_enable,
>>> .disable = x1000_usb_phy_disable,
>>> .is_enabled = x1000_usb_phy_is_enabled,
>>> --
>>> 2.11.0
>>>
>>