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SubjectRe: [PATCH 3/4] clk: mediatek: Add configurable enable control to mtk_pll_data
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On Wed, 2020-07-22 at 16:51 +0800, Nicolas Boichat wrote:
> On Wed, Jul 22, 2020 at 2:50 PM Weiyi Lu <weiyi.lu@mediatek.com> wrote:
> >
> > In all MediaTek PLL design, bit 0 of CON0 register is always
> > the enable bit.
> > However, there's a special case of usbpll on MT8192.
> > The enable bit of usbpll is moved to bit 2 of other register.
> > Add configurable en_reg and base_en_bit for enable control or
> > using the default if without setting in pll data.
> >
> > Signed-off-by: Weiyi Lu <weiyi.lu@mediatek.com>
> > ---
> > drivers/clk/mediatek/clk-mtk.h | 2 ++
> > drivers/clk/mediatek/clk-pll.c | 26 ++++++++++++++++++++++----
> > 2 files changed, 24 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/clk/mediatek/clk-mtk.h b/drivers/clk/mediatek/clk-mtk.h
> > index c3d6756..8bb0b3d 100644
> > --- a/drivers/clk/mediatek/clk-mtk.h
> > +++ b/drivers/clk/mediatek/clk-mtk.h
> > @@ -233,6 +233,8 @@ struct mtk_pll_data {
> > uint32_t pcw_chg_reg;
> > const struct mtk_pll_div_table *div_table;
> > const char *parent_name;
> > + uint32_t en_reg;
> > + uint8_t base_en_bit;
> > };
> >
> > void mtk_clk_register_plls(struct device_node *node,
> > diff --git a/drivers/clk/mediatek/clk-pll.c b/drivers/clk/mediatek/clk-pll.c
> > index f440f2cd..b8ccd42 100644
> > --- a/drivers/clk/mediatek/clk-pll.c
> > +++ b/drivers/clk/mediatek/clk-pll.c
> > @@ -44,6 +44,7 @@ struct mtk_clk_pll {
> > void __iomem *tuner_en_addr;
> > void __iomem *pcw_addr;
> > void __iomem *pcw_chg_addr;
> > + void __iomem *en_addr;
> > const struct mtk_pll_data *data;
> > };
> >
> > @@ -56,7 +57,10 @@ static int mtk_pll_is_prepared(struct clk_hw *hw)
> > {
> > struct mtk_clk_pll *pll = to_mtk_clk_pll(hw);
> >
> > - return (readl(pll->base_addr + REG_CON0) & CON0_BASE_EN) != 0;
> > + if (pll->en_addr)
> > + return (readl(pll->en_addr) & BIT(pll->data->base_en_bit)) != 0;
> > + else
> > + return (readl(pll->base_addr + REG_CON0) & CON0_BASE_EN) != 0;
> > }
> >
> > static unsigned long __mtk_pll_recalc_rate(struct mtk_clk_pll *pll, u32 fin,
> > @@ -251,6 +255,12 @@ static int mtk_pll_prepare(struct clk_hw *hw)
> > r |= pll->data->en_mask;
> > writel(r, pll->base_addr + REG_CON0);
> >
>
> This is not a new change, but I'm wondering if the asymmetry is
> intentional here, that is, prepare sets bit pll->data->en_mask of
> REG_CON0; unprepare clears CON0_BASE_EN of REG_CON0.
>
> With this patch, if pll->en_addr is set, you set both
> pll->data->en_mask _and_ pll->data->base_en_bit, and clear only
> pll->data->base_en_bit.
>

Hi Nicolas,

AFAIK, the asymmetry was intentional.
en_mask is actually a combination of divider enable mask and the pll
enable bit(CON0_BASE_EN).
Even without my patch, it still sets divider enable mask and en_bit, and
only clears en_bit.
You could see the pll_data in clk-mt8192.c of patch [4/4]
Take mainpll as an example,
the enable mask of mainpll is 0xff000001, where 0xff000000 is the
divider enable mask and 0x1 is the en_bit

For usbpll in special case, usbpll doesn't have divider enable mask on
MT8192 so I give nothing(0x00000000) in the en_mask field.
However, the main reason why I don't skip setting the en_mask of MT8192
usbpll is that I'd just like to reserve the divider enable mask for any
special plls with divider enable mask in near future.

> > + if (pll->en_addr) {
> > + r = readl(pll->en_addr);
> > + r |= BIT(pll->data->base_en_bit);
> > + writel(r, pll->en_addr);
> > + }
> > +
> > __mtk_pll_tuner_enable(pll);
> >
> > udelay(20);
> > @@ -277,9 +287,15 @@ static void mtk_pll_unprepare(struct clk_hw *hw)
> >
> > __mtk_pll_tuner_disable(pll);
> >
> > - r = readl(pll->base_addr + REG_CON0);
> > - r &= ~CON0_BASE_EN;
> > - writel(r, pll->base_addr + REG_CON0);
> > + if (pll->en_addr) {
> > + r = readl(pll->en_addr);
> > + r &= ~BIT(pll->data->base_en_bit);
> > + writel(r, pll->en_addr);
> > + } else {
> > + r = readl(pll->base_addr + REG_CON0);
> > + r &= ~CON0_BASE_EN;
> > + writel(r, pll->base_addr + REG_CON0);
> > + }
> >
> > r = readl(pll->pwr_addr) | CON0_ISO_EN;
> > writel(r, pll->pwr_addr);
> > @@ -321,6 +337,8 @@ static struct clk *mtk_clk_register_pll(const struct mtk_pll_data *data,
> > pll->tuner_addr = base + data->tuner_reg;
> > if (data->tuner_en_reg)
> > pll->tuner_en_addr = base + data->tuner_en_reg;
> > + if (data->en_reg)
> > + pll->en_addr = base + data->en_reg;
>
> If the answer to my question above holds (asymmetry is not
> intentional), this patch/the code could be simplified a lot if you
> also added a pll->en_bit member, and, here, did this:
>
> if (pll->en_reg) {
> pll->en_addr = base + data->en_reg;
> pll->end_bit = data->en_bit;
> } else {
> pll->en_addr = pll->base_addr + REG_CON0;
> pll->en_bit = CON0_BASE_EN;
> }
>
> > pll->hw.init = &init;
> > pll->data = data;
> >
> > --
> > 1.8.1.1.dirty

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