From 86378cf646d323d0ce0ac734d444f4d80fd9e43f Mon Sep 17 00:00:00 2001 From: Lars-Peter Clausen Date: Thu, 1 Oct 2020 11:59:47 +0300 Subject: [PATCH] clk: axi-clkgen: Add support for fractional dividers The axi-clkgen has (optional) fractional dividers on the output clock divider and feedback clock divider path. Utilizing the fractional dividers allows for a better resolution of the output clock, being able to synthesize more frequencies. Rework the driver support to support the fractional register fields, both for setting a new rate as well as reading back the current rate from the hardware. For setting the rate if no perfect divider settings were found in non-fractional mode try again in fractional mode and see if better settings can be found. This appears to be the recommended mode of operation. Signed-off-by: Lars-Peter Clausen Signed-off-by: Alexandru Ardelean Link: https://lore.kernel.org/r/20201001085948.21412-1-alexandru.ardelean@analog.com Signed-off-by: Stephen Boyd --- drivers/clk/clk-axi-clkgen.c | 180 +++++++++++++++++++++++++---------- 1 file changed, 129 insertions(+), 51 deletions(-) diff --git a/drivers/clk/clk-axi-clkgen.c b/drivers/clk/clk-axi-clkgen.c index 96f351785b41..1df03cc6d089 100644 --- a/drivers/clk/clk-axi-clkgen.c +++ b/drivers/clk/clk-axi-clkgen.c @@ -27,8 +27,10 @@ #define AXI_CLKGEN_V2_DRP_STATUS_BUSY BIT(16) +#define MMCM_REG_CLKOUT5_2 0x07 #define MMCM_REG_CLKOUT0_1 0x08 #define MMCM_REG_CLKOUT0_2 0x09 +#define MMCM_REG_CLKOUT6_2 0x13 #define MMCM_REG_CLK_FB1 0x14 #define MMCM_REG_CLK_FB2 0x15 #define MMCM_REG_CLK_DIV 0x16 @@ -40,6 +42,7 @@ #define MMCM_CLKOUT_NOCOUNT BIT(6) +#define MMCM_CLK_DIV_DIVIDE BIT(11) #define MMCM_CLK_DIV_NOCOUNT BIT(12) struct axi_clkgen { @@ -107,6 +110,8 @@ static void axi_clkgen_calc_params(unsigned long fin, unsigned long fout, unsigned long d, d_min, d_max, _d_min, _d_max; unsigned long m, m_min, m_max; unsigned long f, dout, best_f, fvco; + unsigned long fract_shift = 0; + unsigned long fvco_min_fract, fvco_max_fract; fin /= 1000; fout /= 1000; @@ -119,42 +124,89 @@ static void axi_clkgen_calc_params(unsigned long fin, unsigned long fout, d_min = max_t(unsigned long, DIV_ROUND_UP(fin, fpfd_max), 1); d_max = min_t(unsigned long, fin / fpfd_min, 80); - m_min = max_t(unsigned long, DIV_ROUND_UP(fvco_min, fin) * d_min, 1); - m_max = min_t(unsigned long, fvco_max * d_max / fin, 64); +again: + fvco_min_fract = fvco_min << fract_shift; + fvco_max_fract = fvco_max << fract_shift; + + m_min = max_t(unsigned long, DIV_ROUND_UP(fvco_min_fract, fin) * d_min, 1); + m_max = min_t(unsigned long, fvco_max_fract * d_max / fin, 64 << fract_shift); for (m = m_min; m <= m_max; m++) { - _d_min = max(d_min, DIV_ROUND_UP(fin * m, fvco_max)); - _d_max = min(d_max, fin * m / fvco_min); + _d_min = max(d_min, DIV_ROUND_UP(fin * m, fvco_max_fract)); + _d_max = min(d_max, fin * m / fvco_min_fract); for (d = _d_min; d <= _d_max; d++) { fvco = fin * m / d; dout = DIV_ROUND_CLOSEST(fvco, fout); - dout = clamp_t(unsigned long, dout, 1, 128); + dout = clamp_t(unsigned long, dout, 1, 128 << fract_shift); f = fvco / dout; if (abs(f - fout) < abs(best_f - fout)) { best_f = f; *best_d = d; - *best_m = m; - *best_dout = dout; + *best_m = m << (3 - fract_shift); + *best_dout = dout << (3 - fract_shift); if (best_f == fout) return; } } } + + /* Lets see if we find a better setting in fractional mode */ + if (fract_shift == 0) { + fract_shift = 3; + goto again; + } } -static void axi_clkgen_calc_clk_params(unsigned int divider, unsigned int *low, - unsigned int *high, unsigned int *edge, unsigned int *nocount) +struct axi_clkgen_div_params { + unsigned int low; + unsigned int high; + unsigned int edge; + unsigned int nocount; + unsigned int frac_en; + unsigned int frac; + unsigned int frac_wf_f; + unsigned int frac_wf_r; + unsigned int frac_phase; +}; + +static void axi_clkgen_calc_clk_params(unsigned int divider, + unsigned int frac_divider, struct axi_clkgen_div_params *params) { - if (divider == 1) - *nocount = 1; - else - *nocount = 0; - *high = divider / 2; - *edge = divider % 2; - *low = divider - *high; + memset(params, 0x0, sizeof(*params)); + + if (divider == 1) { + params->nocount = 1; + return; + } + + if (frac_divider == 0) { + params->high = divider / 2; + params->edge = divider % 2; + params->low = divider - params->high; + } else { + params->frac_en = 1; + params->frac = frac_divider; + + params->high = divider / 2; + params->edge = divider % 2; + params->low = params->high; + + if (params->edge == 0) { + params->high--; + params->frac_wf_r = 1; + } + + if (params->edge == 0 || frac_divider == 1) + params->low--; + if (((params->edge == 0) ^ (frac_divider == 1)) || + (divider == 2 && frac_divider == 1)) + params->frac_wf_f = 1; + + params->frac_phase = params->edge * 4 + frac_divider / 2; + } } static void axi_clkgen_write(struct axi_clkgen *axi_clkgen, @@ -246,15 +298,28 @@ static struct axi_clkgen *clk_hw_to_axi_clkgen(struct clk_hw *clk_hw) return container_of(clk_hw, struct axi_clkgen, clk_hw); } +static void axi_clkgen_set_div(struct axi_clkgen *axi_clkgen, + unsigned int reg1, unsigned int reg2, unsigned int reg3, + struct axi_clkgen_div_params *params) +{ + axi_clkgen_mmcm_write(axi_clkgen, reg1, + (params->high << 6) | params->low, 0xefff); + axi_clkgen_mmcm_write(axi_clkgen, reg2, + (params->frac << 12) | (params->frac_en << 11) | + (params->frac_wf_r << 10) | (params->edge << 7) | + (params->nocount << 6), 0x7fff); + if (reg3 != 0) { + axi_clkgen_mmcm_write(axi_clkgen, reg3, + (params->frac_phase << 11) | (params->frac_wf_f << 10), 0x3c00); + } +} + static int axi_clkgen_set_rate(struct clk_hw *clk_hw, unsigned long rate, unsigned long parent_rate) { struct axi_clkgen *axi_clkgen = clk_hw_to_axi_clkgen(clk_hw); unsigned int d, m, dout; - unsigned int nocount; - unsigned int high; - unsigned int edge; - unsigned int low; + struct axi_clkgen_div_params params; uint32_t filter; uint32_t lock; @@ -269,21 +334,18 @@ static int axi_clkgen_set_rate(struct clk_hw *clk_hw, filter = axi_clkgen_lookup_filter(m - 1); lock = axi_clkgen_lookup_lock(m - 1); - axi_clkgen_calc_clk_params(dout, &low, &high, &edge, &nocount); - axi_clkgen_mmcm_write(axi_clkgen, MMCM_REG_CLKOUT0_1, - (high << 6) | low, 0xefff); - axi_clkgen_mmcm_write(axi_clkgen, MMCM_REG_CLKOUT0_2, - (edge << 7) | (nocount << 6), 0x03ff); + axi_clkgen_calc_clk_params(dout >> 3, dout & 0x7, ¶ms); + axi_clkgen_set_div(axi_clkgen, MMCM_REG_CLKOUT0_1, MMCM_REG_CLKOUT0_2, + MMCM_REG_CLKOUT5_2, ¶ms); - axi_clkgen_calc_clk_params(d, &low, &high, &edge, &nocount); + axi_clkgen_calc_clk_params(d, 0, ¶ms); axi_clkgen_mmcm_write(axi_clkgen, MMCM_REG_CLK_DIV, - (edge << 13) | (nocount << 12) | (high << 6) | low, 0x3fff); + (params.edge << 13) | (params.nocount << 12) | + (params.high << 6) | params.low, 0x3fff); - axi_clkgen_calc_clk_params(m, &low, &high, &edge, &nocount); - axi_clkgen_mmcm_write(axi_clkgen, MMCM_REG_CLK_FB1, - (high << 6) | low, 0xefff); - axi_clkgen_mmcm_write(axi_clkgen, MMCM_REG_CLK_FB2, - (edge << 7) | (nocount << 6), 0x03ff); + axi_clkgen_calc_clk_params(m >> 3, m & 0x7, ¶ms); + axi_clkgen_set_div(axi_clkgen, MMCM_REG_CLK_FB1, MMCM_REG_CLK_FB2, + MMCM_REG_CLKOUT6_2, ¶ms); axi_clkgen_mmcm_write(axi_clkgen, MMCM_REG_LOCK1, lock & 0x3ff, 0x3ff); axi_clkgen_mmcm_write(axi_clkgen, MMCM_REG_LOCK2, @@ -313,35 +375,51 @@ static long axi_clkgen_round_rate(struct clk_hw *hw, unsigned long rate, return min_t(unsigned long long, tmp, LONG_MAX); } +static unsigned int axi_clkgen_get_div(struct axi_clkgen *axi_clkgen, + unsigned int reg1, unsigned int reg2) +{ + unsigned int val1, val2; + unsigned int div; + + axi_clkgen_mmcm_read(axi_clkgen, reg2, &val2); + if (val2 & MMCM_CLKOUT_NOCOUNT) + return 8; + + axi_clkgen_mmcm_read(axi_clkgen, reg1, &val1); + + div = (val1 & 0x3f) + ((val1 >> 6) & 0x3f); + div <<= 3; + + if (val2 & MMCM_CLK_DIV_DIVIDE) { + if ((val2 & BIT(7)) && (val2 & 0x7000) != 0x1000) + div += 8; + else + div += 16; + + div += (val2 >> 12) & 0x7; + } + + return div; +} + static unsigned long axi_clkgen_recalc_rate(struct clk_hw *clk_hw, unsigned long parent_rate) { struct axi_clkgen *axi_clkgen = clk_hw_to_axi_clkgen(clk_hw); unsigned int d, m, dout; - unsigned int reg; unsigned long long tmp; + unsigned int val; - axi_clkgen_mmcm_read(axi_clkgen, MMCM_REG_CLKOUT0_2, ®); - if (reg & MMCM_CLKOUT_NOCOUNT) { - dout = 1; - } else { - axi_clkgen_mmcm_read(axi_clkgen, MMCM_REG_CLKOUT0_1, ®); - dout = (reg & 0x3f) + ((reg >> 6) & 0x3f); - } + dout = axi_clkgen_get_div(axi_clkgen, MMCM_REG_CLKOUT0_1, + MMCM_REG_CLKOUT0_2); + m = axi_clkgen_get_div(axi_clkgen, MMCM_REG_CLK_FB1, + MMCM_REG_CLK_FB2); - axi_clkgen_mmcm_read(axi_clkgen, MMCM_REG_CLK_DIV, ®); - if (reg & MMCM_CLK_DIV_NOCOUNT) + axi_clkgen_mmcm_read(axi_clkgen, MMCM_REG_CLK_DIV, &val); + if (val & MMCM_CLK_DIV_NOCOUNT) d = 1; else - d = (reg & 0x3f) + ((reg >> 6) & 0x3f); - - axi_clkgen_mmcm_read(axi_clkgen, MMCM_REG_CLK_FB2, ®); - if (reg & MMCM_CLKOUT_NOCOUNT) { - m = 1; - } else { - axi_clkgen_mmcm_read(axi_clkgen, MMCM_REG_CLK_FB1, ®); - m = (reg & 0x3f) + ((reg >> 6) & 0x3f); - } + d = (val & 0x3f) + ((val >> 6) & 0x3f); if (d == 0 || dout == 0) return 0; -- 2.34.1