[PATCH 1/7] clk: qcom: add support for setting the duty cycle

[Brian Masney <masneyb@onstation.org>]

Add support for setting the duty cycle via the D register for the
Qualcomm clocks.

Signed-off-by: Brian Masney <masneyb@onstation.org>
---
A few quirks that were noted when varying the speed of CAMSS_GP1_CLK on
msm8974 (Nexus 5 phone):

  - The mnd_width is set to 8 bits, however the d width is actually 7
    bits, at least for this clock. I'm not sure about the other clocks.

  - When the d register has a value less than 17, the following error
    from update_config() is shown: rcg didn't update its configuration.
    So this patch keeps the value of the d register within the range
    [17, 127].

I'm not sure about the relationship of the m, n, and d values,
especially how the 50% duty cycle is calculated by inverting the n
value, so that's why I'm saving the duty cycle ratio for
get_duty_cycle().

 drivers/clk/qcom/clk-rcg.h  |  4 +++
 drivers/clk/qcom/clk-rcg2.c | 61 +++++++++++++++++++++++++++++++++++--
 2 files changed, 63 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/qcom/clk-rcg.h b/drivers/clk/qcom/clk-rcg.h
index 78358b81d249..c3b8732cec8f 100644
--- a/drivers/clk/qcom/clk-rcg.h
+++ b/drivers/clk/qcom/clk-rcg.h
@@ -139,6 +139,8 @@ extern const struct clk_ops clk_dyn_rcg_ops;
  * @freq_tbl: frequency table
  * @clkr: regmap clock handle
  * @cfg_off: defines the cfg register offset from the CMD_RCGR + CFG_REG
+ * @duty_cycle_num: Numerator of the duty cycle ratio
+ * @duty_cycle_den: Denominator of the duty cycle ratio
  */
 struct clk_rcg2 {
 	u32			cmd_rcgr;
@@ -149,6 +151,8 @@ struct clk_rcg2 {
 	const struct freq_tbl	*freq_tbl;
 	struct clk_regmap	clkr;
 	u8			cfg_off;
+	int			duty_cycle_num;
+	int			duty_cycle_den;
 };
 
 #define to_clk_rcg2(_hw) container_of(to_clk_regmap(_hw), struct clk_rcg2, clkr)
diff --git a/drivers/clk/qcom/clk-rcg2.c b/drivers/clk/qcom/clk-rcg2.c
index 8f4b9bec2956..8d685baefe50 100644
--- a/drivers/clk/qcom/clk-rcg2.c
+++ b/drivers/clk/qcom/clk-rcg2.c
@@ -258,7 +258,11 @@ static int clk_rcg2_determine_floor_rate(struct clk_hw *hw,
 	return _freq_tbl_determine_rate(hw, rcg->freq_tbl, req, FLOOR);
 }
 
-static int __clk_rcg2_configure(struct clk_rcg2 *rcg, const struct freq_tbl *f)
+static int __clk_rcg2_configure_with_duty_cycle(struct clk_rcg2 *rcg,
+						const struct freq_tbl *f,
+						int d_reg_val,
+						int duty_cycle_num,
+						int duty_cycle_den)
 {
 	u32 cfg, mask;
 	struct clk_hw *hw = &rcg->clkr.hw;
@@ -280,9 +284,12 @@ static int __clk_rcg2_configure(struct clk_rcg2 *rcg, const struct freq_tbl *f)
 			return ret;
 
 		ret = regmap_update_bits(rcg->clkr.regmap,
-				RCG_D_OFFSET(rcg), mask, ~f->n);
+				RCG_D_OFFSET(rcg), mask, d_reg_val);
 		if (ret)
 			return ret;
+
+		rcg->duty_cycle_num = duty_cycle_num;
+		rcg->duty_cycle_den = duty_cycle_den;
 	}
 
 	mask = BIT(rcg->hid_width) - 1;
@@ -295,6 +302,12 @@ static int __clk_rcg2_configure(struct clk_rcg2 *rcg, const struct freq_tbl *f)
 					mask, cfg);
 }
 
+static int __clk_rcg2_configure(struct clk_rcg2 *rcg, const struct freq_tbl *f)
+{
+	/* Set a 50% duty cycle */
+	return __clk_rcg2_configure_with_duty_cycle(rcg, f, ~f->n, 1, 2);
+}
+
 static int clk_rcg2_configure(struct clk_rcg2 *rcg, const struct freq_tbl *f)
 {
 	int ret;
@@ -353,6 +366,32 @@ static int clk_rcg2_set_floor_rate_and_parent(struct clk_hw *hw,
 	return __clk_rcg2_set_rate(hw, rate, FLOOR);
 }
 
+static int clk_rcg2_get_duty_cycle(struct clk_hw *hw, struct clk_duty *duty)
+{
+	struct clk_rcg2 *rcg = to_clk_rcg2(hw);
+
+	duty->num = rcg->duty_cycle_num;
+	duty->den = rcg->duty_cycle_den;
+
+	return 0;
+}
+
+static int clk_rcg2_set_duty_cycle(struct clk_hw *hw, struct clk_duty *duty)
+{
+	struct clk_rcg2 *rcg = to_clk_rcg2(hw);
+	int ret, d_reg_val, mask;
+
+	mask = BIT(rcg->mnd_width - 1) - 1;
+	d_reg_val = mask - (((mask - 17) * duty->num) / duty->den);
+	ret = __clk_rcg2_configure_with_duty_cycle(rcg, rcg->freq_tbl,
+						   d_reg_val, duty->num,
+						   duty->den);
+	if (ret)
+		return ret;
+
+	return update_config(rcg);
+}
+
 const struct clk_ops clk_rcg2_ops = {
 	.is_enabled = clk_rcg2_is_enabled,
 	.get_parent = clk_rcg2_get_parent,
@@ -361,6 +400,8 @@ const struct clk_ops clk_rcg2_ops = {
 	.determine_rate = clk_rcg2_determine_rate,
 	.set_rate = clk_rcg2_set_rate,
 	.set_rate_and_parent = clk_rcg2_set_rate_and_parent,
+	.get_duty_cycle = clk_rcg2_get_duty_cycle,
+	.set_duty_cycle = clk_rcg2_set_duty_cycle,
 };
 EXPORT_SYMBOL_GPL(clk_rcg2_ops);
 
@@ -372,6 +413,8 @@ const struct clk_ops clk_rcg2_floor_ops = {
 	.determine_rate = clk_rcg2_determine_floor_rate,
 	.set_rate = clk_rcg2_set_floor_rate,
 	.set_rate_and_parent = clk_rcg2_set_floor_rate_and_parent,
+	.get_duty_cycle = clk_rcg2_get_duty_cycle,
+	.set_duty_cycle = clk_rcg2_set_duty_cycle,
 };
 EXPORT_SYMBOL_GPL(clk_rcg2_floor_ops);
 
@@ -499,6 +542,8 @@ const struct clk_ops clk_edp_pixel_ops = {
 	.set_rate = clk_edp_pixel_set_rate,
 	.set_rate_and_parent = clk_edp_pixel_set_rate_and_parent,
 	.determine_rate = clk_edp_pixel_determine_rate,
+	.get_duty_cycle = clk_rcg2_get_duty_cycle,
+	.set_duty_cycle = clk_rcg2_set_duty_cycle,
 };
 EXPORT_SYMBOL_GPL(clk_edp_pixel_ops);
 
@@ -557,6 +602,8 @@ const struct clk_ops clk_byte_ops = {
 	.set_rate = clk_byte_set_rate,
 	.set_rate_and_parent = clk_byte_set_rate_and_parent,
 	.determine_rate = clk_byte_determine_rate,
+	.get_duty_cycle = clk_rcg2_get_duty_cycle,
+	.set_duty_cycle = clk_rcg2_set_duty_cycle,
 };
 EXPORT_SYMBOL_GPL(clk_byte_ops);
 
@@ -627,6 +674,8 @@ const struct clk_ops clk_byte2_ops = {
 	.set_rate = clk_byte2_set_rate,
 	.set_rate_and_parent = clk_byte2_set_rate_and_parent,
 	.determine_rate = clk_byte2_determine_rate,
+	.get_duty_cycle = clk_rcg2_get_duty_cycle,
+	.set_duty_cycle = clk_rcg2_set_duty_cycle,
 };
 EXPORT_SYMBOL_GPL(clk_byte2_ops);
 
@@ -717,6 +766,8 @@ const struct clk_ops clk_pixel_ops = {
 	.set_rate = clk_pixel_set_rate,
 	.set_rate_and_parent = clk_pixel_set_rate_and_parent,
 	.determine_rate = clk_pixel_determine_rate,
+	.get_duty_cycle = clk_rcg2_get_duty_cycle,
+	.set_duty_cycle = clk_rcg2_set_duty_cycle,
 };
 EXPORT_SYMBOL_GPL(clk_pixel_ops);
 
@@ -804,6 +855,8 @@ const struct clk_ops clk_gfx3d_ops = {
 	.set_rate = clk_gfx3d_set_rate,
 	.set_rate_and_parent = clk_gfx3d_set_rate_and_parent,
 	.determine_rate = clk_gfx3d_determine_rate,
+	.get_duty_cycle = clk_rcg2_get_duty_cycle,
+	.set_duty_cycle = clk_rcg2_set_duty_cycle,
 };
 EXPORT_SYMBOL_GPL(clk_gfx3d_ops);
 
@@ -942,6 +995,8 @@ const struct clk_ops clk_rcg2_shared_ops = {
 	.determine_rate = clk_rcg2_determine_rate,
 	.set_rate = clk_rcg2_shared_set_rate,
 	.set_rate_and_parent = clk_rcg2_shared_set_rate_and_parent,
+	.get_duty_cycle = clk_rcg2_get_duty_cycle,
+	.set_duty_cycle = clk_rcg2_set_duty_cycle,
 };
 EXPORT_SYMBOL_GPL(clk_rcg2_shared_ops);
 
@@ -1081,6 +1136,8 @@ static const struct clk_ops clk_rcg2_dfs_ops = {
 	.get_parent = clk_rcg2_get_parent,
 	.determine_rate = clk_rcg2_dfs_determine_rate,
 	.recalc_rate = clk_rcg2_dfs_recalc_rate,
+	.get_duty_cycle = clk_rcg2_get_duty_cycle,
+	.set_duty_cycle = clk_rcg2_set_duty_cycle,
 };
 
 static int clk_rcg2_enable_dfs(const struct clk_rcg_dfs_data *data,
-- 
2.21.0