From a048fe996b5109d3c94c243bb0733419fbd0ed8f Mon Sep 17 00:00:00 2001 From: Anson Huang Date: Tue, 30 Apr 2019 00:57:22 +0000 Subject: clk: imx: pllv4: add fractional-N pll support 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 Reviewed-by: Dong Aisheng --- drivers/clk/imx/clk-pllv4.c | 72 +++++++++++++++++++++++++++++++++++++++------ 1 file changed, 63 insertions(+), 9 deletions(-) (limited to 'drivers/clk') diff --git a/drivers/clk/imx/clk-pllv4.c b/drivers/clk/imx/clk-pllv4.c index d38bc9f87c1d..d7e62c3620d3 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; } -- cgit v1.2.3