[PATCH v5 09/21] clk: tegra: pll: Add logic for handling SDM data

From: Rhyland Klein
Date: Tue May 12 2015 - 13:26:37 EST

This adds logic for taking SDM_DIN (Sigma Delta Modulator) setting into
the equation to calculate the effective N value for PLL which supports
fractional divider.

The effective N = NDIV + 1/2 + SDM_DIN/2^13, where NDIV is the integer
feedback divider.

Signed-off-by: Rhyland Klein <rklein@xxxxxxxxxx>
---
v5:
- made use of sdm_en_mask when possible to clean up logic
- added kerneldoc info for new struct params
- Added info about SDM near sdm_set_data
- rewrote check in sdm_set_data to make it clearer

drivers/clk/tegra/clk-pll.c | 66 ++++++++++++++++++++++++++++++++++++++++++-
drivers/clk/tegra/clk.h | 15 +++++++++-
2 files changed, 79 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/tegra/clk-pll.c b/drivers/clk/tegra/clk-pll.c
index 13d86c5b234d..8b27cb6fe992 100644
--- a/drivers/clk/tegra/clk-pll.c
+++ b/drivers/clk/tegra/clk-pll.c
@@ -187,17 +187,23 @@
#define pll_readl_base(p) pll_readl(p->params->base_reg, p)
#define pll_readl_misc(p) pll_readl(p->params->misc_reg, p)
#define pll_override_readl(offset, p) readl_relaxed(p->pmc + offset)
+#define pll_readl_sdm_din(p) pll_readl(p->params->sdm_din_reg, p)
+#define pll_readl_sdm_ctrl(p) pll_readl(p->params->sdm_ctrl_reg, p)

#define pll_writel(val, offset, p) writel_relaxed(val, p->clk_base + offset)
#define pll_writel_base(val, p) pll_writel(val, p->params->base_reg, p)
#define pll_writel_misc(val, p) pll_writel(val, p->params->misc_reg, p)
#define pll_override_writel(val, offset, p) writel(val, p->pmc + offset)
+#define pll_writel_sdm_din(val, p) pll_writel(val, p->params->sdm_din_reg, p)
+#define pll_writel_sdm_ctrl(val, p) pll_writel(val, p->params->sdm_ctrl_reg, p)

#define mask(w) ((1 << (w)) - 1)
#define divm_mask(p) mask(p->params->div_nmp->divm_width)
#define divn_mask(p) mask(p->params->div_nmp->divn_width)
#define divp_mask(p) (p->params->flags & TEGRA_PLLU ? PLLU_POST_DIVP_MASK :\
mask(p->params->div_nmp->divp_width))
+#define sdm_din_mask(p) p->params->sdm_din_mask
+#define sdm_en_mask(p) p->params->sdm_ctrl_en_mask

#define divm_shift(p) (p)->params->div_nmp->divm_shift
#define divn_shift(p) (p)->params->div_nmp->divn_shift
@@ -211,6 +217,9 @@
#define divn_max(p) (divn_mask(p))
#define divp_max(p) (1 << (divp_mask(p)))

+#define sdin_din_to_data(din) ((u16)((din) ? : 0xFFFFU))
+#define sdin_data_to_din(dat) (((dat) == 0xFFFFU) ? 0 : (s16)dat)
+
static struct div_nmp default_nmp = {
.divn_shift = PLL_BASE_DIVN_SHIFT,
.divn_width = PLL_BASE_DIVN_WIDTH,
@@ -429,6 +438,7 @@ static int _get_table_rate(struct clk_hw *hw,
cfg->n = sel->n;
cfg->p = sel->p;
cfg->cpcon = sel->cpcon;
+ cfg->sdm_data = sel->sdm_data;

return 0;
}
@@ -495,6 +505,42 @@ static int _calc_rate(struct clk_hw *hw, struct tegra_clk_pll_freq_table *cfg,
return 0;
}

+/*
+ * SDM (Sigma Delta Modulator) divisor is 16-bit 2's complement signed number
+ * within (-2^12 ... 2^12-1) range. Represented in PLL data structure as
+ * unsigned 16-bit value, with "0" divisor mapped to 0xFFFF. Data "0" is used
+ * to indicate that SDM is disabled.
+ *
+ * Effective ndiv value when SDM is enabled: ndiv + 1/2 + sdm_din/2^13
+ */
+static void clk_pll_set_sdm_data(struct clk_hw *hw,
+ struct tegra_clk_pll_freq_table *cfg)
+{
+ struct tegra_clk_pll *pll = to_clk_pll(hw);
+ u32 val;
+ bool enabled;
+
+ if (!pll->params->sdm_din_reg)
+ return;
+
+ if (cfg->sdm_data) {
+ val = pll_readl_sdm_din(pll) & (~sdm_din_mask(pll));
+ val |= sdin_data_to_din(cfg->sdm_data) & sdm_din_mask(pll);
+ pll_writel_sdm_din(val, pll);
+ }
+
+ val = pll_readl_sdm_ctrl(pll);
+ enabled = (val & sdm_en_mask(pll));
+
+ if (cfg->sdm_data == 0 && enabled)
+ val &= ~pll->params->sdm_ctrl_en_mask;
+
+ if (cfg->sdm_data != 0 && !enabled)
+ val |= pll->params->sdm_ctrl_en_mask;
+
+ pll_writel_sdm_ctrl(val, pll);
+}
+
static void _update_pll_mnp(struct tegra_clk_pll *pll,
struct tegra_clk_pll_freq_table *cfg)
{
@@ -527,6 +573,8 @@ static void _update_pll_mnp(struct tegra_clk_pll *pll,
(cfg->p << divp_shift(pll));

pll_writel_base(val, pll);
+
+ clk_pll_set_sdm_data(&pll->hw, cfg);
}
}

@@ -552,6 +600,14 @@ static void _get_pll_mnp(struct tegra_clk_pll *pll,
cfg->m = (val >> div_nmp->divm_shift) & divm_mask(pll);
cfg->n = (val >> div_nmp->divn_shift) & divn_mask(pll);
cfg->p = (val >> div_nmp->divp_shift) & divp_mask(pll);
+
+ if (pll->params->sdm_din_reg) {
+ if (sdm_en_mask(pll) & pll_readl_sdm_ctrl(pll)) {
+ val = pll_readl_sdm_din(pll);
+ val &= sdm_din_mask(pll);
+ cfg->sdm_data = sdin_din_to_data(val);
+ }
+ }
}
}

@@ -633,7 +689,8 @@ static int clk_pll_set_rate(struct clk_hw *hw, unsigned long rate,

_get_pll_mnp(pll, &old_cfg);

- if (old_cfg.m != cfg.m || old_cfg.n != cfg.n || old_cfg.p != cfg.p)
+ if (old_cfg.m != cfg.m || old_cfg.n != cfg.n || old_cfg.p != cfg.p ||
+ old_cfg.sdm_data != cfg.sdm_data)
ret = _program_pll(hw, &cfg, rate);

if (pll->lock)
@@ -697,6 +754,9 @@ static unsigned long clk_pll_recalc_rate(struct clk_hw *hw,
pdiv = 1;
}

+ if (pll->params->set_gain)
+ pll->params->set_gain(&cfg);
+
cfg.m *= pdiv;

rate *= cfg.n;
@@ -978,6 +1038,7 @@ static int clk_pllxc_set_rate(struct clk_hw *hw, unsigned long rate,
static long clk_pll_ramp_round_rate(struct clk_hw *hw, unsigned long rate,
unsigned long *prate)
{
+ struct tegra_clk_pll *pll = to_clk_pll(hw);
struct tegra_clk_pll_freq_table cfg;
int ret, p_div;
u64 output_rate = *prate;
@@ -990,6 +1051,9 @@ static long clk_pll_ramp_round_rate(struct clk_hw *hw, unsigned long rate,
if (p_div < 0)
return p_div;

+ if (pll->params->set_gain)
+ pll->params->set_gain(&cfg);
+
output_rate *= cfg.n;
do_div(output_rate, cfg.m * p_div);

diff --git a/drivers/clk/tegra/clk.h b/drivers/clk/tegra/clk.h
index afcdd8575355..e78133822233 100644
--- a/drivers/clk/tegra/clk.h
+++ b/drivers/clk/tegra/clk.h
@@ -110,14 +110,16 @@ struct clk *tegra_clk_register_mc(const char *name, const char *parent_name,
* @m: input divider
* @p: post divider
* @cpcon: charge pump current
+ * @sdm_data: fraction divider setting (0 = disabled)
*/
struct tegra_clk_pll_freq_table {
unsigned long input_rate;
unsigned long output_rate;
- u16 n;
+ u32 n;
u16 m;
u8 p;
u8 cpcon;
+ u16 sdm_data;
};

/**
@@ -174,6 +176,10 @@ struct div_nmp {
* @lock_enable_bit_idx: Bit index to enable PLL lock
* @iddq_reg: PLL IDDQ register offset
* @iddq_bit_idx: Bit index to enable PLL IDDQ
+ * @sdm_din_reg: Register offset where SDM settings are
+ * @sdm_din_mask: Mask of SDM divider bits
+ * @sdm_ctrl_reg: Register offset where SDM enable is
+ * @sdm_ctrl_en_mask: Mask of SDM enable bit
* @aux_reg: AUX register offset
* @dyn_ramp_reg: Dynamic ramp control register offset
* @ext_misc_reg: Miscellaneous control register offsets
@@ -188,6 +194,8 @@ struct div_nmp {
* @div_nmp: offsets and widths on n, m and p fields
* @freq_table: array of frequencies supported by PLL
* @fixed_rate: PLL rate if it is fixed
+ * @set_gain: Callback to adjust N div for SDM enabled
+ * PLL's based on fractional divider value.
*
* Flags:
* TEGRA_PLL_USE_LOCK - This flag indicated to use lock bits for
@@ -225,6 +233,10 @@ struct tegra_clk_pll_params {
u32 lock_enable_bit_idx;
u32 iddq_reg;
u32 iddq_bit_idx;
+ u32 sdm_din_reg;
+ u32 sdm_din_mask;
+ u32 sdm_ctrl_reg;
+ u32 sdm_ctrl_en_mask;
u32 aux_reg;
u32 dyn_ramp_reg;
u32 ext_misc_reg[MAX_PLL_MISC_REG_COUNT];
@@ -239,6 +251,7 @@ struct tegra_clk_pll_params {
struct div_nmp *div_nmp;
struct tegra_clk_pll_freq_table *freq_table;
unsigned long fixed_rate;
+ void (*set_gain)(struct tegra_clk_pll_freq_table *cfg);
};

#define TEGRA_PLL_USE_LOCK BIT(0)
--
1.7.9.5

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