[v3,02/11] clk: qcom: clk-alpha-pll: Add support for dynamic update for slewing PLLs

diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c
index 03cc7aa092480bfdd9eaa986d44f0545944b3b89..fe9e5d5344d7fa9a8a1f220f8982fbafc875c4c1 100644
--- a/drivers/clk/qcom/clk-alpha-pll.c
+++ b/drivers/clk/qcom/clk-alpha-pll.c
@@ -2758,3 +2758,173 @@  const struct clk_ops clk_alpha_pll_regera_ops = {
 	.set_rate = clk_zonda_pll_set_rate,
 };
 EXPORT_SYMBOL_GPL(clk_alpha_pll_regera_ops);
+
+static int clk_alpha_pll_slew_update(struct clk_alpha_pll *pll)
+{
+	int ret;
+	u32 val;
+
+	regmap_update_bits(pll->clkr.regmap, PLL_MODE(pll), PLL_UPDATE, PLL_UPDATE);
+	regmap_read(pll->clkr.regmap, PLL_MODE(pll), &val);
+
+	ret = wait_for_pll_update(pll);
+	if (ret)
+		return ret;
+	/*
+	 * Hardware programming mandates a wait of at least 570ns before polling the LOCK
+	 * detect bit. Have a delay of 1us just to be safe.
+	 */
+	mb();
+	udelay(1);
+
+	return wait_for_pll_enable_lock(pll);
+}
+
+static int clk_alpha_pll_slew_set_rate(struct clk_hw *hw, unsigned long rate,
+					unsigned long parent_rate)
+{
+	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
+	unsigned long freq_hz;
+	const struct pll_vco *curr_vco, *vco;
+	u32 l, alpha_width = pll_alpha_width(pll);
+	u64 a;
+
+	freq_hz =  alpha_pll_round_rate(rate, parent_rate, &l, &a, alpha_width);
+	if (freq_hz != rate) {
+		pr_err("alpha_pll: Call clk_set_rate with rounded rates!\n");
+		return -EINVAL;
+	}
+
+	curr_vco = alpha_pll_find_vco(pll, clk_hw_get_rate(hw));
+	if (!curr_vco) {
+		pr_err("alpha pll: not in a valid vco range\n");
+		return -EINVAL;
+	}
+
+	vco = alpha_pll_find_vco(pll, freq_hz);
+	if (!vco) {
+		pr_err("alpha pll: not in a valid vco range\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * Dynamic pll update will not support switching frequencies across
+	 * vco ranges. In those cases fall back to normal alpha set rate.
+	 */
+	if (curr_vco->val != vco->val)
+		return clk_alpha_pll_set_rate(hw, rate, parent_rate);
+
+	a = a << (ALPHA_REG_BITWIDTH - ALPHA_BITWIDTH);
+
+	regmap_write(pll->clkr.regmap, PLL_L_VAL(pll), l);
+	regmap_write(pll->clkr.regmap, PLL_ALPHA_VAL(pll), a);
+	regmap_write(pll->clkr.regmap, PLL_ALPHA_VAL_U(pll), a >> 32);
+
+	/* Ensure that the write above goes through before proceeding. */
+	mb();
+
+	if (clk_hw_is_enabled(hw))
+		return clk_alpha_pll_slew_update(pll);
+
+	return 0;
+}
+
+/*
+ * Slewing plls should be bought up at frequency which is in the middle of the
+ * desired VCO range. So after bringing up the pll at calibration freq, set it
+ * back to desired frequency(that was set by previous clk_set_rate).
+ */
+static int clk_alpha_pll_calibrate(struct clk_hw *hw)
+{
+	unsigned long calibration_freq, freq_hz;
+	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
+	struct clk_hw *parent;
+	const struct pll_vco *vco;
+	u32 l, alpha_width = pll_alpha_width(pll);
+	int rc;
+	u64 a;
+
+	parent = clk_hw_get_parent(hw);
+	if (!parent) {
+		pr_err("alpha pll: no valid parent found\n");
+		return -EINVAL;
+	}
+
+	vco = alpha_pll_find_vco(pll, clk_hw_get_rate(hw));
+	if (!vco) {
+		pr_err("alpha pll: not in a valid vco range\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * As during slewing plls vco_sel won't be allowed to change, vco table
+	 * should have only one entry table, i.e. index = 0, find the
+	 * calibration frequency.
+	 */
+	calibration_freq = (pll->vco_table[0].min_freq + pll->vco_table[0].max_freq) / 2;
+
+	freq_hz = alpha_pll_round_rate(calibration_freq, clk_hw_get_rate(parent),
+					&l, &a, alpha_width);
+	if (freq_hz != calibration_freq) {
+		pr_err("alpha_pll: call clk_set_rate with rounded rates!\n");
+		return -EINVAL;
+	}
+
+	/* Setup PLL for calibration frequency */
+	a <<= (ALPHA_REG_BITWIDTH - ALPHA_BITWIDTH);
+
+	regmap_write(pll->clkr.regmap, PLL_L_VAL(pll), l);
+	regmap_write(pll->clkr.regmap, PLL_ALPHA_VAL(pll), a);
+	regmap_write(pll->clkr.regmap, PLL_ALPHA_VAL_U(pll), a >> 32);
+
+	regmap_update_bits(pll->clkr.regmap, PLL_USER_CTL(pll), PLL_VCO_MASK << PLL_VCO_SHIFT,
+				vco->val << PLL_VCO_SHIFT);
+
+	/* Bringup the pll at calibration frequency */
+	rc = clk_alpha_pll_enable(hw);
+	if (rc) {
+		pr_err("alpha pll calibration failed\n");
+		return rc;
+	}
+
+	/*
+	 * PLL is already running at calibration frequency.
+	 * So slew pll to the previously set frequency.
+	 */
+	freq_hz = alpha_pll_round_rate(clk_hw_get_rate(hw),
+			clk_hw_get_rate(parent), &l, &a, alpha_width);
+
+	pr_debug("pll %s: setting back to required rate %lu, freq_hz %ld\n",
+		clk_hw_get_name(hw), clk_hw_get_rate(hw), freq_hz);
+
+	/* Setup the PLL for the new frequency */
+	a <<= (ALPHA_REG_BITWIDTH - ALPHA_BITWIDTH);
+
+	regmap_write(pll->clkr.regmap, PLL_L_VAL(pll), l);
+	regmap_write(pll->clkr.regmap, PLL_ALPHA_VAL(pll), a);
+	regmap_write(pll->clkr.regmap, PLL_ALPHA_VAL_U(pll), a >> 32);
+
+	regmap_update_bits(pll->clkr.regmap, PLL_USER_CTL(pll), PLL_ALPHA_EN, PLL_ALPHA_EN);
+
+	return clk_alpha_pll_slew_update(pll);
+}
+
+static int clk_alpha_pll_slew_enable(struct clk_hw *hw)
+{
+	int rc;
+
+	rc = clk_alpha_pll_calibrate(hw);
+	if (rc)
+		return rc;
+
+	return clk_alpha_pll_enable(hw);
+}
+
+const struct clk_ops clk_alpha_pll_slew_ops = {
+	.enable = clk_alpha_pll_slew_enable,
+	.disable = clk_alpha_pll_disable,
+	.recalc_rate = clk_alpha_pll_recalc_rate,
+	.round_rate = clk_alpha_pll_round_rate,
+	.set_rate = clk_alpha_pll_slew_set_rate,
+};
+EXPORT_SYMBOL(clk_alpha_pll_slew_ops);
diff --git a/drivers/clk/qcom/clk-alpha-pll.h b/drivers/clk/qcom/clk-alpha-pll.h
index 55eca04b23a1fc3f3554f43a8fdd329a524dad0e..f149d10247bd4a85521940a1255cd019bde4729a 100644
--- a/drivers/clk/qcom/clk-alpha-pll.h
+++ b/drivers/clk/qcom/clk-alpha-pll.h
@@ -195,6 +195,7 @@  extern const struct clk_ops clk_alpha_pll_rivian_evo_ops;
 #define clk_alpha_pll_postdiv_rivian_evo_ops clk_alpha_pll_postdiv_fabia_ops
 
 extern const struct clk_ops clk_alpha_pll_regera_ops;
+extern const struct clk_ops clk_alpha_pll_slew_ops;
 
 void clk_alpha_pll_configure(struct clk_alpha_pll *pll, struct regmap *regmap,
 			     const struct alpha_pll_config *config);