The pllv4 supports fractional-N function, the formula is:
PLL output freq = input * (mult + num/denom),
This patch adds fractional-N function support, including
clock round rate, calculate rate and set rate, with this
patch, the clock rate of APLL in clock tree is more accurate
than before:
Without fraction:
apll_pre_sel 1 1 1 24000000 0
0 50000
apll_pre_div 1 1 2 24000000 0
0 50000
apll 1 1 2 528000000 0
0 50000
apll_pfd3 0 0 0 792000000 0
0 50000
apll_pfd2 0 0 0 339428571 0
0 50000
apll_pfd1 0 0 0 352000000 0
0 50000
usdhc0 0 0 0 352000000 0
0 50000
apll_pfd0 1 1 1 352000000 0
0 50000
With fraction:
apll_pre_sel 1 1 1 24000000 0
0 50000
apll_pre_div 1 1 2 24000000 0
0 50000
apll 1 1 2 529200000 0
0 50000
apll_pfd3 0 0 0 793800000 0
0 50000
apll_pfd2 0 0 0 340200000 0
0 50000
apll_pfd1 0 0 0 352800000 0
0 50000
usdhc0 0 0 0 352800000 0
0 50000
apll_pfd0 1 1 1 352800000 0
0 50000
Signed-off-by: Anson Huang <anson.hu...@nxp.com>
Reviewed-by: Dong Aisheng <aisheng.d...@nxp.com>
---
drivers/clk/imx/clk-pllv4.c | 72 +++++++++++++++++++++++++++++++++++++++------
1 file changed, 63 insertions(+), 9 deletions(-)
diff --git a/drivers/clk/imx/clk-pllv4.c b/drivers/clk/imx/clk-pllv4.c
index d38bc9f..d7e62c3 100644
--- a/drivers/clk/imx/clk-pllv4.c
+++ b/drivers/clk/imx/clk-pllv4.c
@@ -30,6 +30,9 @@
/* PLL Denominator Register (xPLLDENOM) */
#define PLL_DENOM_OFFSET 0x14
+#define MAX_MFD 0x3fffffff
+#define DEFAULT_MFD 1000000
+
struct clk_pllv4 {
struct clk_hw hw;
void __iomem *base;
@@ -64,13 +67,20 @@ static unsigned long clk_pllv4_recalc_rate(struct clk_hw
*hw,
unsigned long parent_rate)
{
struct clk_pllv4 *pll = to_clk_pllv4(hw);
- u32 div;
+ u32 mult, mfn, mfd;
+ u64 temp64;
+
+ mult = readl_relaxed(pll->base + PLL_CFG_OFFSET);
+ mult &= BM_PLL_MULT;
+ mult >>= BP_PLL_MULT;
- div = readl_relaxed(pll->base + PLL_CFG_OFFSET);
- div &= BM_PLL_MULT;
- div >>= BP_PLL_MULT;
+ mfn = readl_relaxed(pll->base + PLL_NUM_OFFSET);
+ mfd = readl_relaxed(pll->base + PLL_DENOM_OFFSET);
+ temp64 = parent_rate;
+ temp64 *= mfn;
+ do_div(temp64, mfd);
- return parent_rate * div;
+ return (parent_rate * mult) + (u32)temp64;
}
static long clk_pllv4_round_rate(struct clk_hw *hw, unsigned long rate,
@@ -78,14 +88,46 @@ static long clk_pllv4_round_rate(struct clk_hw *hw,
unsigned long rate,
{
unsigned long parent_rate = *prate;
unsigned long round_rate, i;
+ u32 mfn, mfd = DEFAULT_MFD;
+ bool found = false;
+ u64 temp64;
for (i = 0; i < ARRAY_SIZE(pllv4_mult_table); i++) {
round_rate = parent_rate * pllv4_mult_table[i];
- if (rate >= round_rate)
- return round_rate;
+ if (rate >= round_rate) {
+ found = true;
+ break;
+ }
+ }
+
+ if (!found) {
+ pr_warn("%s: unable to round rate %lu, parent rate %lu\n",
+ clk_hw_get_name(hw), rate, parent_rate);
+ return 0;
}
- return round_rate;
+ if (parent_rate <= MAX_MFD)
+ mfd = parent_rate;
+
+ temp64 = (u64)(rate - round_rate);
+ temp64 *= mfd;
+ do_div(temp64, parent_rate);
+ mfn = temp64;
+
+ /*
+ * NOTE: The value of numerator must always be configured to be
+ * less than the value of the denominator. If we can't get a proper
+ * pair of mfn/mfd, we simply return the round_rate without using
+ * the frac part.
+ */
+ if (mfn >= mfd)
+ return round_rate;
+
+ temp64 = (u64)parent_rate;
+ temp64 *= mfn;
+ do_div(temp64, mfd);
+
+ return round_rate + (u32)temp64;
}
static bool clk_pllv4_is_valid_mult(unsigned int mult)
@@ -105,18 +147,30 @@ static int clk_pllv4_set_rate(struct clk_hw *hw, unsigned
long rate,
unsigned long parent_rate)
{
struct clk_pllv4 *pll = to_clk_pllv4(hw);
- u32 val, mult;
+ u32 val, mult, mfn, mfd = DEFAULT_MFD;
+ u64 temp64;
mult = rate / parent_rate;
if (!clk_pllv4_is_valid_mult(mult))
return -EINVAL;
+ if (parent_rate <= MAX_MFD)
+ mfd = parent_rate;
+
+ temp64 = (u64)(rate - mult * parent_rate);
+ temp64 *= mfd;
+ do_div(temp64, parent_rate);
+ mfn = temp64;
+
val = readl_relaxed(pll->base + PLL_CFG_OFFSET);
val &= ~BM_PLL_MULT;
val |= mult << BP_PLL_MULT;
writel_relaxed(val, pll->base + PLL_CFG_OFFSET);
+ writel_relaxed(mfn, pll->base + PLL_NUM_OFFSET);
+ writel_relaxed(mfd, pll->base + PLL_DENOM_OFFSET);
+
return 0;
}
--
2.7.4
