Re: [PATCH] clk: mediatek: Add MT8173 MMPLL change rate support

From: Heiko Stübner
Date: Tue Jul 07 2015 - 04:59:14 EST

Hi James,

Am Dienstag, 2. Juni 2015, 13:26:00 schrieb James Liao:
> MT8173 MMPLL frequency settings are different from common PLLs.
> It needs different post divider settings for some ranges of frequency.
> This patch add support for MT8173 MMPLL frequency setting, includes:
>
> 1. Add div-rate table for PLLs.
> 2. Increase the max ost divider setting from 3 (/8) to 4 (/16).
> 3. Write postdiv and pcw settings at the same time.
>
> Signed-off-by: James Liao <jamesjj.liao@xxxxxxxxxxxx>
> ---
> drivers/clk/mediatek/clk-mt8173.c | 24 +++++++++++++++++++++---
> drivers/clk/mediatek/clk-mtk.h | 1 +
> drivers/clk/mediatek/clk-pll.c | 37
> +++++++++++++++++++++++++------------ 3 files changed, 47 insertions(+), 15
> deletions(-)
>
> diff --git a/drivers/clk/mediatek/clk-mt8173.c
> b/drivers/clk/mediatek/clk-mt8173.c index 357b080..821de7d 100644
> --- a/drivers/clk/mediatek/clk-mt8173.c
> +++ b/drivers/clk/mediatek/clk-mt8173.c
> @@ -779,8 +779,9 @@ CLK_OF_DECLARE(mtk_pericfg, "mediatek,mt8173-pericfg",
> mtk_pericfg_init);
>
> #define CON0_MT8173_RST_BAR BIT(24)
>
> -#define PLL(_id, _name, _reg, _pwr_reg, _en_mask, _flags, _pcwbits,
> _pd_reg, _pd_shift, \ - _tuner_reg, _pcw_reg, _pcw_shift) { \
> +#define PLL_B(_id, _name, _reg, _pwr_reg, _en_mask, _flags, _pcwbits, \
> + _pd_reg, _pd_shift, _tuner_reg, _pcw_reg, \
> + _pcw_shift, _div_rate) { \
> .id = _id, \
> .name = _name, \
> .reg = _reg, \
> @@ -795,14 +796,31 @@ CLK_OF_DECLARE(mtk_pericfg, "mediatek,mt8173-pericfg",
> mtk_pericfg_init); .tuner_reg = _tuner_reg, \
> .pcw_reg = _pcw_reg, \
> .pcw_shift = _pcw_shift, \
> + .div_rate = _div_rate, \
> }
>
> +#define PLL(_id, _name, _reg, _pwr_reg, _en_mask, _flags, _pcwbits, \
> + _pd_reg, _pd_shift, _tuner_reg, _pcw_reg, \
> + _pcw_shift) \
> + PLL_B(_id, _name, _reg, _pwr_reg, _en_mask, _flags, _pcwbits, \
> + _pd_reg, _pd_shift, _tuner_reg, _pcw_reg, _pcw_shift, \
> + NULL)
> +
> +const unsigned long mmpll_div_rate[] = {

static?

> + MT8173_PLL_FMAX,
> + 1000000000,
> + 702000000,
> + 253500000,
> + 126750000,
> + 0,

it's more common to label sentinel entries (the 0 marking the end) with
/* sentinel */
instead of value 0.


If I'm reading the code correctly, this is a mapping divider -> frequency,
right? So it may be nice to make this a bit more explicit, like:

struct mtk_pll_div_table {
unsigned int freq;
unsigned int div;
};

static const struct mtk_pll_div_table mmpll_div_rate[] = {
{ .freq = MT8173_PLL_FMAX, .div = 0 },
{ .freq = 1000000000, .div = 1 },
{ .freq = 702000000, .div = 2 },
{ .freq = 253500000, .div = 3 },
{ .freq = 126750000, .div = 4 },
{ /* sentinel */ },
};


> +};
> +
> static const struct mtk_pll_data plls[] = {
> PLL(CLK_APMIXED_ARMCA15PLL, "armca15pll", 0x200, 0x20c, 0x00000001, 0,
21,
> 0x204, 24, 0x0, 0x204, 0), PLL(CLK_APMIXED_ARMCA7PLL, "armca7pll", 0x210,
> 0x21c, 0x00000001, 0, 21, 0x214, 24, 0x0, 0x214, 0),
> PLL(CLK_APMIXED_MAINPLL, "mainpll", 0x220, 0x22c, 0xf0000101, HAVE_RST_BAR,
> 21, 0x220, 4, 0x0, 0x224, 0), PLL(CLK_APMIXED_UNIVPLL, "univpll", 0x230,
> 0x23c, 0xfe000001, HAVE_RST_BAR, 7, 0x230, 4, 0x0, 0x234, 14),
> - PLL(CLK_APMIXED_MMPLL, "mmpll", 0x240, 0x24c, 0x00000001, 0, 21, 0x244,
> 24, 0x0, 0x244, 0), + PLL_B(CLK_APMIXED_MMPLL, "mmpll", 0x240, 0x24c,
> 0x00000001, 0, 21, 0x244, 24, 0x0, 0x244, 0, mmpll_div_rate),
> PLL(CLK_APMIXED_MSDCPLL, "msdcpll", 0x250, 0x25c, 0x00000001, 0, 21, 0x250,
> 4, 0x0, 0x254, 0), PLL(CLK_APMIXED_VENCPLL, "vencpll", 0x260, 0x26c,
> 0x00000001, 0, 21, 0x260, 4, 0x0, 0x264, 0), PLL(CLK_APMIXED_TVDPLL,
> "tvdpll", 0x270, 0x27c, 0x00000001, 0, 21, 0x270, 4, 0x0, 0x274, 0), diff
> --git a/drivers/clk/mediatek/clk-mtk.h b/drivers/clk/mediatek/clk-mtk.h
> index 61035b9..645af7c 100644
> --- a/drivers/clk/mediatek/clk-mtk.h
> +++ b/drivers/clk/mediatek/clk-mtk.h
> @@ -150,6 +150,7 @@ struct mtk_pll_data {
> int pcwbits;
> uint32_t pcw_reg;
> int pcw_shift;
> + const unsigned long *div_rate;
> };
>
> void __init 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 44409e9..4680a09 100644
> --- a/drivers/clk/mediatek/clk-pll.c
> +++ b/drivers/clk/mediatek/clk-pll.c
> @@ -90,20 +90,23 @@ static unsigned long __mtk_pll_recalc_rate(struct
> mtk_clk_pll *pll, u32 fin, static void mtk_pll_set_rate_regs(struct
> mtk_clk_pll *pll, u32 pcw, int postdiv)
> {

-------------

> - u32 con1, pd, val;
> + u32 con1, val;
> int pll_en;
>
> - /* set postdiv */
> - pd = readl(pll->pd_addr);
> - pd &= ~(POSTDIV_MASK << pll->data->pd_shift);
> - pd |= (ffs(postdiv) - 1) << pll->data->pd_shift;
> - writel(pd, pll->pd_addr);
> -
> pll_en = readl(pll->base_addr + REG_CON0) & CON0_BASE_EN;
>
> - /* set pcw */
> - val = readl(pll->pcw_addr);
> + /* set postdiv */
> + val = readl(pll->pd_addr);
> + val &= ~(POSTDIV_MASK << pll->data->pd_shift);
> + val |= (ffs(postdiv) - 1) << pll->data->pd_shift;
> +
> + /* postdiv and pcw need to set at the same time if on same register */
> + if (pll->pd_addr != pll->pcw_addr) {
> + writel(val, pll->pd_addr);
> + val = readl(pll->pcw_addr);
> + }
>
> + /* set pcw */
> val &= ~GENMASK(pll->data->pcw_shift + pll->data->pcwbits - 1,
> pll->data->pcw_shift);
> val |= pcw << pll->data->pcw_shift;

This whole block probably wants to be a separate patch ;-) .

While it may not affect previous pll implementations, it changes how register
accesses are handled and should not hide in another patch.



> @@ -135,16 +138,26 @@ static void mtk_pll_calc_values(struct mtk_clk_pll
> *pll, u32 *pcw, u32 *postdiv, u32 freq, u32 fin)
> {
> unsigned long fmin = 1000 * MHZ;
> + const unsigned long *div_rate = pll->data->div_rate;
> u64 _pcw;
> u32 val;
>
> if (freq > pll->data->fmax)
> freq = pll->data->fmax;
>
> - for (val = 0; val < 4; val++) {
> + if (div_rate) {
> + for (val = 1; div_rate[val] != 0; val++) {
> + if (freq > div_rate[val])
> + break;
> + }
> + val--;

if you're changing the table struct, this of course also would need to be
adapted.


Hmm, what I don't understand is, what does MT8173_PLL_FMAX in the table, if
you ignore it here all the time?

So the table should probably look more like [when using the concept from
above]

static const struct mtk_pll_div_table mmpll_div_rate[] = {
{ .freq = 1000000000, .div = 0 },
{ .freq = 702000000, .div = 1 },
{ .freq = 253500000, .div = 2 },
{ .freq = 126750000, .div = 3 },
{ /* sentinel */ },
};


> *postdiv = 1 << val;
> - if (freq * *postdiv >= fmin)
> - break;
> + } else {
> + for (val = 0; val < 5; val++) {
> + *postdiv = 1 << val;
> + if ((u64)freq * *postdiv >= fmin)
> + break;
> + }
> }
>
> /* _pcw = freq * postdiv / fin * 2^pcwfbits */


Heiko
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