[PATCH v1 1/7] clk: qcom: clk-alpha-pll: Add support for Fabia PLL calibration

[Taniya Das <tdas@codeaurora.org>]

In the cases where the PLL is not calibrated the PLL could fail to lock.
Add support for prepare ops which would take care of the same.

Fabia PLL user/test control registers might required to be configured, so
add support for configuring them.

Signed-off-by: Taniya Das <tdas@codeaurora.org>
---
 drivers/clk/qcom/clk-alpha-pll.c | 84 +++++++++++++++++++++++++++++++++++++---
 drivers/clk/qcom/clk-alpha-pll.h |  4 ++
 2 files changed, 83 insertions(+), 5 deletions(-)

diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c
index 055318f..8cb77ca 100644
--- a/drivers/clk/qcom/clk-alpha-pll.c
+++ b/drivers/clk/qcom/clk-alpha-pll.c
@@ -1024,6 +1024,25 @@ void clk_fabia_pll_configure(struct clk_alpha_pll *pll, struct regmap *regmap,
 		regmap_write(regmap, PLL_CONFIG_CTL(pll),
 						config->config_ctl_val);

+	if (config->config_ctl_hi_val)
+		regmap_write(regmap, PLL_CONFIG_CTL_U(pll),
+						config->config_ctl_hi_val);
+
+	if (config->user_ctl_val)
+		regmap_write(regmap, PLL_USER_CTL(pll), config->user_ctl_val);
+
+	if (config->user_ctl_hi_val)
+		regmap_write(regmap, PLL_USER_CTL_U(pll),
+						config->user_ctl_hi_val);
+
+	if (config->test_ctl_val)
+		regmap_write(regmap, PLL_TEST_CTL(pll),
+						config->test_ctl_val);
+
+	if (config->test_ctl_hi_val)
+		regmap_write(regmap, PLL_TEST_CTL_U(pll),
+						config->test_ctl_hi_val);
+
 	if (config->post_div_mask) {
 		mask = config->post_div_mask;
 		val = config->post_div_val;
@@ -1141,15 +1160,11 @@ static int alpha_pll_fabia_set_rate(struct clk_hw *hw, unsigned long rate,
 						unsigned long prate)
 {
 	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
-	u32 val, l, alpha_width = pll_alpha_width(pll);
+	u32 l, alpha_width = pll_alpha_width(pll);
 	u64 a;
 	unsigned long rrate;
 	int ret = 0;

-	ret = regmap_read(pll->clkr.regmap, PLL_MODE(pll), &val);
-	if (ret)
-		return ret;
-
 	rrate = alpha_pll_round_rate(rate, prate, &l, &a, alpha_width);

 	/*
@@ -1167,7 +1182,66 @@ static int alpha_pll_fabia_set_rate(struct clk_hw *hw, unsigned long rate,
 	return __clk_alpha_pll_update_latch(pll);
 }

+static int alpha_pll_fabia_prepare(struct clk_hw *hw)
+{
+	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
+	const struct pll_vco *vco;
+	struct clk_hw *parent_hw;
+	unsigned long cal_freq, rrate;
+	u32 cal_l, regval, alpha_width = pll_alpha_width(pll);
+	u64 a;
+	int ret;
+
+	/* Check if calibration needs to be done i.e. PLL is in reset */
+	ret = regmap_read(pll->clkr.regmap, PLL_MODE(pll), &regval);
+	if (ret)
+		return ret;
+
+	/* Return early if calibration is not needed. */
+	if (regval & PLL_RESET_N)
+		return 0;
+
+	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;
+	}
+
+	cal_freq = DIV_ROUND_CLOSEST((pll->vco_table[0].min_freq +
+				pll->vco_table[0].max_freq) * 54, 100);
+
+	parent_hw = clk_hw_get_parent(hw);
+	if (!parent_hw)
+		return -EINVAL;
+
+	rrate = alpha_pll_round_rate(cal_freq, clk_hw_get_rate(parent_hw),
+					&cal_l, &a, alpha_width);
+	/*
+	 * Due to a limited number of bits for fractional rate programming, the
+	 * rounded up rate could be marginally higher than the requested rate.
+	 */
+	if (rrate > (cal_freq + FABIA_PLL_RATE_MARGIN) || rrate < cal_freq) {
+		pr_err("Call set rate on the PLL with rounded rates!\n");
+		return -EINVAL;
+	}
+
+	/* Setup PLL for calibration frequency */
+	regmap_write(pll->clkr.regmap, PLL_ALPHA_VAL(pll), cal_l);
+
+	/* Bringup the pll at calibration frequency */
+	ret = clk_alpha_pll_enable(hw);
+	if (ret) {
+		pr_err("alpha pll calibration failed\n");
+		return ret;
+	}
+
+	clk_alpha_pll_disable(hw);
+
+	return 0;
+}
+
 const struct clk_ops clk_alpha_pll_fabia_ops = {
+	.prepare = alpha_pll_fabia_prepare,
 	.enable = alpha_pll_fabia_enable,
 	.disable = alpha_pll_fabia_disable,
 	.is_enabled = clk_alpha_pll_is_enabled,
diff --git a/drivers/clk/qcom/clk-alpha-pll.h b/drivers/clk/qcom/clk-alpha-pll.h
index 15f27f4..b03eea0 100644
--- a/drivers/clk/qcom/clk-alpha-pll.h
+++ b/drivers/clk/qcom/clk-alpha-pll.h
@@ -94,6 +94,10 @@ struct alpha_pll_config {
 	u32 alpha_hi;
 	u32 config_ctl_val;
 	u32 config_ctl_hi_val;
+	u32 user_ctl_val;
+	u32 user_ctl_hi_val;
+	u32 test_ctl_val;
+	u32 test_ctl_hi_val;
 	u32 main_output_mask;
 	u32 aux_output_mask;
 	u32 aux2_output_mask;
--
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