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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 <lars@metafoo.de>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20201001085948.21412-1-alexandru.ardelean@analog.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
This commit is contained in:
Lars-Peter Clausen 2020-10-01 11:59:47 +03:00 committed by Stephen Boyd
parent 9123e3a74e
commit 86378cf646
1 changed files with 130 additions and 52 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

182
drivers/clk/clk-axi-clkgen.c
View File

@ -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)
{
if (divider == 1)
*nocount = 1;
else
*nocount = 0;
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;
};
*high = divider / 2;
*edge = divider % 2;
*low = divider - *high;
static void axi_clkgen_calc_clk_params(unsigned int divider,
unsigned int frac_divider, struct axi_clkgen_div_params *params)
{
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, &params);
axi_clkgen_set_div(axi_clkgen, MMCM_REG_CLKOUT0_1, MMCM_REG_CLKOUT0_2,
MMCM_REG_CLKOUT5_2, &params);
axi_clkgen_calc_clk_params(d, &low, &high, &edge, &nocount);
axi_clkgen_calc_clk_params(d, 0, &params);
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, &params);
axi_clkgen_set_div(axi_clkgen, MMCM_REG_CLK_FB1, MMCM_REG_CLK_FB2,
MMCM_REG_CLKOUT6_2, &params);
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, &reg);
if (reg & MMCM_CLKOUT_NOCOUNT) {
dout = 1;
} else {
axi_clkgen_mmcm_read(axi_clkgen, MMCM_REG_CLKOUT0_1, &reg);
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, &reg);
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, &reg);
if (reg & MMCM_CLKOUT_NOCOUNT) {
m = 1;
} else {
axi_clkgen_mmcm_read(axi_clkgen, MMCM_REG_CLK_FB1, &reg);
m = (reg & 0x3f) + ((reg >> 6) & 0x3f);
}
d = (val & 0x3f) + ((val >> 6) & 0x3f);
if (d == 0 || dout == 0)
return 0;