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Subject: Re: [PATCH v7 02/11] clk: Ingenic: Adjust cgu code to make it
 compatible with I2S PLL.
To:     Paul Cercueil <paul@crapouillou.net>
Cc:     sboyd@kernel.org, mturquette@baylibre.com, robh+dt@kernel.org,
        linux-clk@vger.kernel.org, linux-mips@vger.kernel.org,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
        dongsheng.qiu@ingenic.com, aric.pzqi@ingenic.com,
        rick.tyliu@ingenic.com, sihui.liu@ingenic.com,
        jun.jiang@ingenic.com, sernia.zhou@foxmail.com
References: <1627119286-125821-1-git-send-email-zhouyanjie@wanyeetech.com>
 <1627119286-125821-3-git-send-email-zhouyanjie@wanyeetech.com>
 <5RY2YQ.VQN2WB38KM14@crapouillou.net>
From:   Zhou Yanjie <zhouyanjie@wanyeetech.com>
Message-ID: <a98a8078-c388-8af4-a605-20e2edb3363d@wanyeetech.com>
Date:   Sat, 28 Aug 2021 01:46:50 +0800
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Hi Paul,

On 2021/8/19 下午5:37, Paul Cercueil wrote:
> Hi Zhou,
>
> Le sam., juil. 24 2021 at 17:34:37 +0800, 周琰杰 (Zhou Yanjie) 
> <zhouyanjie@wanyeetech.com> a écrit :
>> I2S PLL is different from the APLL/MPLL, which have no OD bits,
>> no stable bit, but have parent clock selection bits, therefore,
>> it is necessary to modify the CGU PLL correlation code to make
>> it compatible with I2S PLL.
>>
>> Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
>
> Could you split this commit into three:
> - one commit to support PLLs with no OD bit,
> - one commit to support PLLs with no stable bit,
> - one commit to support setting the parents of PLLs.


Sure, I will do it in the next version.


>
>> ---
>>
>> Notes:
>>     v5:
>>     New patch.
>>
>>     v5->v6:
>>     Change the type of stable_bit from u8 to s8, because a negative 
>> value will appear
>>     when the stable_bit bit does not exist.
>>     Reported-by: kernel test robot <lkp@intel.com>
>>
>>     v6->v7:
>>     No change.
>>
>>  drivers/clk/ingenic/cgu.c | 118 
>> ++++++++++++++++++++++++++++++++++++++++------
>>  drivers/clk/ingenic/cgu.h |  10 +++-
>>  2 files changed, 111 insertions(+), 17 deletions(-)
>>
>> diff --git a/drivers/clk/ingenic/cgu.c b/drivers/clk/ingenic/cgu.c
>> index 266c759..391bf50 100644
>> --- a/drivers/clk/ingenic/cgu.c
>> +++ b/drivers/clk/ingenic/cgu.c
>> @@ -76,6 +76,85 @@ ingenic_cgu_gate_set(struct ingenic_cgu *cgu,
>>   * PLL operations
>>   */
>>
>> +static u8 ingenic_pll_get_parent(struct clk_hw *hw)
>> +{
>> +    struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw);
>> +    const struct ingenic_cgu_clk_info *clk_info = 
>> to_clk_info(ingenic_clk);
>> +    struct ingenic_cgu *cgu = ingenic_clk->cgu;
>> +    const struct ingenic_cgu_pll_info *pll_info;
>> +    u32 reg;
>> +    u8 i, hw_idx, idx = 0;
>> +
>> +    BUG_ON(clk_info->type != CGU_CLK_PLL);
>> +    pll_info = &clk_info->pll;
>> +
>> +    if (pll_info->mux_bits <= 0)
>> +        return 1;
>> +
>> +    reg = readl(cgu->base + pll_info->reg);
>> +    hw_idx = (reg >> pll_info->mux_shift) &
>> +         GENMASK(pll_info->mux_bits - 1, 0);
>> +
>> +    /*
>> +     * Convert the hardware index to the parent index by skipping
>> +     * over any -1's in the parents array.
>> +     */
>> +    for (i = 0; i < hw_idx; i++) {
>> +        if (clk_info->parents[i] != -1)
>> +            idx++;
>> +    }
>> +
>> +    return idx;
>> +}
>> +
>> +static int ingenic_pll_set_parent(struct clk_hw *hw, u8 idx)
>> +{
>> +    struct ingenic_clk *ingenic_clk = to_ingenic_clk(hw);
>> +    const struct ingenic_cgu_clk_info *clk_info = 
>> to_clk_info(ingenic_clk);
>> +    struct ingenic_cgu *cgu = ingenic_clk->cgu;
>> +    const struct ingenic_cgu_pll_info *pll_info;
>> +    unsigned long flags;
>> +    u32 reg;
>> +    u8 curr_idx, hw_idx, num_poss;
>> +
>> +    BUG_ON(clk_info->type != CGU_CLK_PLL);
>> +    pll_info = &clk_info->pll;
>> +
>> +    if (pll_info->mux_bits <= 0)
>> +        return 0;
>> +
>> +    /*
>> +     * Convert the parent index to the hardware index by adding
>> +     * 1 for any -1 in the parents array preceding the given
>> +     * index. That is, we want the index of idx'th entry in
>> +     * clk_info->parents which does not equal -1.
>> +     */
>> +    hw_idx = curr_idx = 0;
>> +    num_poss = 1 << pll_info->mux_bits;
>> +    for (; hw_idx < num_poss; hw_idx++) {
>> +        if (clk_info->parents[hw_idx] == -1)
>> +            continue;
>> +        if (curr_idx == idx)
>> +            break;
>> +        curr_idx++;
>> +    }
>> +
>> +    /* idx should always be a valid parent */
>> +    BUG_ON(curr_idx != idx);
>> +
>> +    spin_lock_irqsave(&cgu->lock, flags);
>> +
>> +    /* write the register */
>> +    reg = readl(cgu->base + pll_info->reg);
>> +    reg &= ~(GENMASK(pll_info->mux_bits - 1, 0) << 
>> pll_info->mux_shift);
>> +    reg |= hw_idx << pll_info->mux_shift;
>> +    writel(reg, cgu->base + pll_info->reg);
>> +
>> +    spin_unlock_irqrestore(&cgu->lock, flags);
>> +
>> +    return 0;
>> +}
>> +
>>  static unsigned long
>>  ingenic_pll_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
>>  {
>> @@ -96,8 +175,20 @@ ingenic_pll_recalc_rate(struct clk_hw *hw, 
>> unsigned long parent_rate)
>>      m += pll_info->m_offset;
>>      n = (ctl >> pll_info->n_shift) & GENMASK(pll_info->n_bits - 1, 0);
>>      n += pll_info->n_offset;
>> -    od_enc = ctl >> pll_info->od_shift;
>> -    od_enc &= GENMASK(pll_info->od_bits - 1, 0);
>> +
>> +    if (pll_info->od_encoding) {
>> +        od_enc = ctl >> pll_info->od_shift;
>> +        od_enc &= GENMASK(pll_info->od_bits - 1, 0);
>> +
>> +        for (od = 0; od < pll_info->od_max; od++) {
>> +            if (pll_info->od_encoding[od] == od_enc)
>> +                break;
>> +        }
>> +        BUG_ON(od == pll_info->od_max);
>> +        od++;
>> +    } else {
>> +        od = 1;
>> +    }
>>
>>      if (pll_info->bypass_bit >= 0) {
>>          ctl = readl(cgu->base + pll_info->bypass_reg);
>> @@ -108,15 +199,7 @@ ingenic_pll_recalc_rate(struct clk_hw *hw, 
>> unsigned long parent_rate)
>>              return parent_rate;
>>      }
>>
>> -    for (od = 0; od < pll_info->od_max; od++) {
>> -        if (pll_info->od_encoding[od] == od_enc)
>> -            break;
>> -    }
>> -    BUG_ON(od == pll_info->od_max);
>> -    od++;
>> -
>> -    return div_u64((u64)parent_rate * m * pll_info->rate_multiplier,
>> -        n * od);
>> +    return div_u64((u64)parent_rate * m * pll_info->rate_multiplier, 
>> n * od);
>>  }
>>
>>  static void
>> @@ -215,13 +298,15 @@ ingenic_pll_set_rate(struct clk_hw *hw, 
>> unsigned long req_rate,
>>      ctl &= ~(GENMASK(pll_info->n_bits - 1, 0) << pll_info->n_shift);
>>      ctl |= (n - pll_info->n_offset) << pll_info->n_shift;
>>
>> -    ctl &= ~(GENMASK(pll_info->od_bits - 1, 0) << pll_info->od_shift);
>> -    ctl |= pll_info->od_encoding[od - 1] << pll_info->od_shift;
>> +    if (pll_info->od_encoding) {
>> +        ctl &= ~(GENMASK(pll_info->od_bits - 1, 0) << 
>> pll_info->od_shift);
>> +        ctl |= pll_info->od_encoding[od - 1] << pll_info->od_shift;
>> +    }
>>
>>      writel(ctl, cgu->base + pll_info->reg);
>>
>>      /* If the PLL is enabled, verify that it's stable */
>> -    if (ctl & BIT(pll_info->enable_bit))
>> +    if ((pll_info->stable_bit >= 0) && (ctl & 
>> BIT(pll_info->enable_bit)))
>>          ret = ingenic_pll_check_stable(cgu, pll_info);
>>
>>      spin_unlock_irqrestore(&cgu->lock, flags);
>> @@ -292,6 +377,9 @@ static int ingenic_pll_is_enabled(struct clk_hw *hw)
>>  }
>>
>>  static const struct clk_ops ingenic_pll_ops = {
>> +    .get_parent = ingenic_pll_get_parent,
>> +    .set_parent = ingenic_pll_set_parent,
>
> If you move the "pll" field of struct ingenic_cgu_clk_info to the 
> nameless "struct" that follows it, you will then be able to use the 
> other fields as well. That means that you'll be able to use 
> ingenic_clk_get_parent() / ingenic_clk_set_parent() instead of 
> duplicating code.


Sure, I'll try it.


>
>> +
>>      .recalc_rate = ingenic_pll_recalc_rate,
>>      .round_rate = ingenic_pll_round_rate,
>>      .set_rate = ingenic_pll_set_rate,
>> @@ -672,7 +760,7 @@ static int ingenic_register_clock(struct 
>> ingenic_cgu *cgu, unsigned idx)
>>          clk_init.flags |= CLK_SET_RATE_PARENT;
>>      }
>>
>> -    if (caps & (CGU_CLK_MUX | CGU_CLK_CUSTOM)) {
>> +    if (caps & (CGU_CLK_PLL | CGU_CLK_MUX | CGU_CLK_CUSTOM)) {
>
> I tend to disagree with this - clocks that support parenting should 
> use the CGU_CLK_MUX flag. I know it conflicts with CGU_CLK_PLL right 
> now, but with the change I suggested above, your clock should be able 
> to use .type = CGU_CLK_PLL | CGU_CLK_MUX.


Sure.


Thanks and best regards!


>
> Cheers,
> -Paul
>
>>          clk_init.num_parents = 0;
>>
>>          if (caps & CGU_CLK_MUX)
>> diff --git a/drivers/clk/ingenic/cgu.h b/drivers/clk/ingenic/cgu.h
>> index bfc2b9c..30d575d 100644
>> --- a/drivers/clk/ingenic/cgu.h
>> +++ b/drivers/clk/ingenic/cgu.h
>> @@ -18,6 +18,10 @@
>>   * struct ingenic_cgu_pll_info - information about a PLL
>>   * @reg: the offset of the PLL's control register within the CGU
>>   * @rate_multiplier: the multiplier needed by pll rate calculation
>> + * @mux_shift: the number of bits to shift the mux value by (ie. the
>> + *           index of the lowest bit of the mux value in the I2S PLL's
>> + *           control register)
>> + * @mux_bits: the size of the mux field in bits
>>   * @m_shift: the number of bits to shift the multiplier value by 
>> (ie. the
>>   *           index of the lowest bit of the multiplier value in the 
>> PLL's
>>   *           control register)
>> @@ -42,19 +46,21 @@
>>   * @bypass_bit: the index of the bypass bit in the PLL control 
>> register, or
>>   *              -1 if there is no bypass bit
>>   * @enable_bit: the index of the enable bit in the PLL control register
>> - * @stable_bit: the index of the stable bit in the PLL control register
>> + * @stable_bit: the index of the stable bit in the PLL control 
>> register, or
>> + *              -1 if there is no stable bit
>>   */
>>  struct ingenic_cgu_pll_info {
>>      unsigned reg;
>>      unsigned rate_multiplier;
>>      const s8 *od_encoding;
>> +    u8 mux_shift, mux_bits;
>>      u8 m_shift, m_bits, m_offset;
>>      u8 n_shift, n_bits, n_offset;
>>      u8 od_shift, od_bits, od_max;
>>      unsigned bypass_reg;
>>      s8 bypass_bit;
>>      u8 enable_bit;
>> -    u8 stable_bit;
>> +    s8 stable_bit;
>>      void (*calc_m_n_od)(const struct ingenic_cgu_pll_info *pll_info,
>>                  unsigned long rate, unsigned long parent_rate,
>>                  unsigned int *m, unsigned int *n, unsigned int *od);
>> -- 
>> 2.7.4
>>
>