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clk: meson: fractional pll support

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Fractional MPLLs are a superset of the existing AmLogic MPLLs. They add
in a couple of new bitfields for further dividing the clock rate to
achieve rates with fractional hertz.

Tested-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Michael Turquette <mturquette@baylibre.com>
This commit is contained in:
Michael Turquette 2016-06-06 18:08:15 -07:00
parent 1c50da4f27
commit 4a47295144
2 changed files with 45 additions and 2 deletions
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32
drivers/clk/meson/clk-pll.c
View File

@ -53,7 +53,7 @@ static unsigned long meson_clk_pll_recalc_rate(struct clk_hw *hw,
struct parm *p;
unsigned long parent_rate_mhz = parent_rate / 1000000;
unsigned long rate_mhz;
u16 n, m, od;
u16 n, m, frac = 0, od, od2 = 0;
u32 reg;
p = &pll->n;
@ -68,7 +68,21 @@ static unsigned long meson_clk_pll_recalc_rate(struct clk_hw *hw,
reg = readl(pll->base + p->reg_off);
od = PARM_GET(p->width, p->shift, reg);
rate_mhz = (parent_rate_mhz * m / n) >> od;
p = &pll->od2;
if (p->width) {
reg = readl(pll->base + p->reg_off);
od2 = PARM_GET(p->width, p->shift, reg);
}
p = &pll->frac;
if (p->width) {
reg = readl(pll->base + p->reg_off);
frac = PARM_GET(p->width, p->shift, reg);
rate_mhz = (parent_rate_mhz * m + \
(parent_rate_mhz * frac >> 12)) * 2 / n;
rate_mhz = rate_mhz >> od >> od2;
} else
rate_mhz = (parent_rate_mhz * m / n) >> od >> od2;
return rate_mhz * 1000000;
}
@ -155,6 +169,20 @@ static int meson_clk_pll_set_rate(struct clk_hw *hw, unsigned long rate,
reg = PARM_SET(p->width, p->shift, reg, rate_set->od);
writel(reg, pll->base + p->reg_off);
p = &pll->od2;
if (p->width) {
reg = readl(pll->base + p->reg_off);
reg = PARM_SET(p->width, p->shift, reg, rate_set->od2);
writel(reg, pll->base + p->reg_off);
}
p = &pll->frac;
if (p->width) {
reg = readl(pll->base + p->reg_off);
reg = PARM_SET(p->width, p->shift, reg, rate_set->frac);
writel(reg, pll->base + p->reg_off);
}
p = &pll->n;
ret = meson_clk_pll_wait_lock(pll, p);
if (ret) {

15
drivers/clk/meson/clkc.h
View File

@ -40,7 +40,10 @@ struct pll_rate_table {
u16 m;
u16 n;
u16 od;
u16 od2;
u16 frac;
};
#define PLL_RATE(_r, _m, _n, _od) \
{ \
.rate = (_r), \
@ -49,12 +52,24 @@ struct pll_rate_table {
.od = (_od), \
} \
#define PLL_FRAC_RATE(_r, _m, _n, _od, _od2, _frac) \
{ \
.rate = (_r), \
.m = (_m), \
.n = (_n), \
.od = (_od), \
.od2 = (_od2), \
.frac = (_frac), \
} \
struct meson_clk_pll {
struct clk_hw hw;
void __iomem *base;
struct parm m;
struct parm n;
struct parm frac;
struct parm od;
struct parm od2;
const struct pll_rate_table *rate_table;
unsigned int rate_count;
spinlock_t *lock;