The DFLL hardware supports two modes (I2C and PWM) for voltage control
when requesting a frequency. In this patch, we introduce PWM mode support.

To support that, we re-organize the LUT for unifying the table for both
cases of I2C and PWM mode. And generate that based on regulator info.
For the PWM-based regulator, we get this info from DT. And do the same as
the case of I2C LUT, which can help to map the PMIC voltage ID and voltages
that the regulator supported.

The other parts are the support code for initializing the DFLL hardware
to support PWM mode. Also, the register debugfs file is slightly
reworked to only show the i2c registers when I2C mode is in use.

Based on the work of Peter De Schrijver [off-list ref].

Signed-off-by: Joseph Lo <redacted>
---
*V2:
 - move reg_init_uV to be with the PWM related variables
 - fix the variable type to 'unsigned long' if it needs to catch the
 return value from 'dev_pm_opp_get_voltage'
 - update to use lut_uv table for LUT look up. This makes the generic
 lut_uv table to work with both PWM and I2C mode.
---
 drivers/clk/tegra/clk-dfll.c | 435 +++++++++++++++++++++++++++++------
 1 file changed, 369 insertions(+), 66 deletions(-)

diff --git a/drivers/clk/tegra/clk-dfll.c b/drivers/clk/tegra/clk-dfll.c
index 609e363dabf8..72e02898006c 100644
--- a/drivers/clk/tegra/clk-dfll.c
+++ b/drivers/clk/tegra/clk-dfll.c

@@ -1,7 +1,7 @@
 /*
  * clk-dfll.c - Tegra DFLL clock source common code
  *
- * Copyright (C) 2012-2014 NVIDIA Corporation. All rights reserved.
+ * Copyright (C) 2012-2018 NVIDIA Corporation. All rights reserved.
  *
  * Aleksandr Frid <afrid@nvidia.com>
  * Paul Walmsley <pwalmsley@nvidia.com>

@@ -47,6 +47,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/pinctrl/consumer.h>
 #include <linux/pm_opp.h>
 #include <linux/pm_runtime.h>
 #include <linux/regmap.h>

@@ -243,6 +244,12 @@ enum dfll_tune_range {
 	DFLL_TUNE_LOW = 1,
 };
 
+
+enum tegra_dfll_pmu_if {
+	TEGRA_DFLL_PMU_I2C = 0,
+	TEGRA_DFLL_PMU_PWM = 1,
+};
+
 /**
  * struct dfll_rate_req - target DFLL rate request data
  * @rate: target frequency, after the postscaling

@@ -300,10 +307,19 @@ struct tegra_dfll {
 	u32				i2c_reg;
 	u32				i2c_slave_addr;
 
-	/* i2c_lut array entries are regulator framework selectors */
-	unsigned			i2c_lut[MAX_DFLL_VOLTAGES];
-	int				i2c_lut_size;
-	u8				lut_min, lut_max, lut_safe;
+	/* lut array entries are regulator framework selectors or PWM values*/
+	unsigned			lut[MAX_DFLL_VOLTAGES];
+	unsigned long			lut_uv[MAX_DFLL_VOLTAGES];
+	int				lut_size;
+	u8				lut_bottom, lut_min, lut_max, lut_safe;
+
+	/* PWM interface */
+	enum tegra_dfll_pmu_if		pmu_if;
+	unsigned long			pwm_rate;
+	struct pinctrl			*pwm_pin;
+	struct pinctrl_state		*pwm_enable_state;
+	struct pinctrl_state		*pwm_disable_state;
+	u32				reg_init_uV;
 };
 
 #define clk_hw_to_dfll(_hw) container_of(_hw, struct tegra_dfll, dfll_clk_hw)

@@ -489,6 +505,34 @@ static void dfll_set_mode(struct tegra_dfll *td,
 	dfll_wmb(td);
 }
 
+/*
+ * DVCO rate control
+ */
+
+static unsigned long get_dvco_rate_below(struct tegra_dfll *td, u8 out_min)
+{
+	struct dev_pm_opp *opp;
+	unsigned long rate, prev_rate;
+	unsigned long uv, min_uv;
+
+	min_uv = td->lut_uv[out_min];
+	for (rate = 0, prev_rate = 0; ; rate++) {
+		opp = dev_pm_opp_find_freq_ceil(td->soc->dev, &rate);
+		if (IS_ERR(opp))
+			break;
+
+		uv = dev_pm_opp_get_voltage(opp);
+		dev_pm_opp_put(opp);
+
+		if (uv && uv > min_uv)
+			return prev_rate;
+
+		prev_rate = rate;
+	}
+
+	return prev_rate;
+}
+
 /*
  * DFLL-to-I2C controller interface
  */

@@ -518,6 +562,118 @@ static int dfll_i2c_set_output_enabled(struct tegra_dfll *td, bool enable)
 	return 0;
 }
 
+
+/*
+ * DFLL-to-PWM controller interface
+ */
+
+/**
+ * dfll_pwm_set_output_enabled - enable/disable PWM voltage requests
+ * @td: DFLL instance
+ * @enable: whether to enable or disable the PWM voltage requests
+ *
+ * Set the master enable control for PWM control value updates. If disabled,
+ * then the PWM signal is not driven. Also configure the PWM output pad
+ * to the appropriate state.
+ */
+static int dfll_pwm_set_output_enabled(struct tegra_dfll *td, bool enable)
+{
+	int ret;
+	u32 val, div;
+
+	if (enable) {
+		ret = pinctrl_select_state(td->pwm_pin, td->pwm_enable_state);
+		if (ret < 0) {
+			dev_err(td->dev, "setting enable state failed\n");
+			return -EINVAL;
+		}
+		val = dfll_readl(td, DFLL_OUTPUT_CFG);
+		val &= ~DFLL_OUTPUT_CFG_PWM_DIV_MASK;
+		div = DIV_ROUND_UP(td->ref_rate, td->pwm_rate);
+		val |= (div << DFLL_OUTPUT_CFG_PWM_DIV_SHIFT)
+				& DFLL_OUTPUT_CFG_PWM_DIV_MASK;
+		dfll_writel(td, val, DFLL_OUTPUT_CFG);
+		dfll_wmb(td);
+
+		val |= DFLL_OUTPUT_CFG_PWM_ENABLE;
+		dfll_writel(td, val, DFLL_OUTPUT_CFG);
+		dfll_wmb(td);
+	} else {
+		ret = pinctrl_select_state(td->pwm_pin, td->pwm_disable_state);
+		if (ret < 0)
+			dev_warn(td->dev, "setting disable state failed\n");
+
+		val = dfll_readl(td, DFLL_OUTPUT_CFG);
+		val &= ~DFLL_OUTPUT_CFG_PWM_ENABLE;
+		dfll_writel(td, val, DFLL_OUTPUT_CFG);
+		dfll_wmb(td);
+	}
+
+	return 0;
+}
+
+/**
+ * dfll_set_force_output_value - set fixed value for force output
+ * @td: DFLL instance
+ * @out_val: value to force output
+ *
+ * Set the fixed value for force output, DFLL will output this value when
+ * force output is enabled.
+ */
+static u32 dfll_set_force_output_value(struct tegra_dfll *td, u8 out_val)
+{
+	u32 val = dfll_readl(td, DFLL_OUTPUT_FORCE);
+
+	val = (val & DFLL_OUTPUT_FORCE_ENABLE) | (out_val & OUT_MASK);
+	dfll_writel(td, val, DFLL_OUTPUT_FORCE);
+	dfll_wmb(td);
+
+	return dfll_readl(td, DFLL_OUTPUT_FORCE);
+}
+
+/**
+ * dfll_set_force_output_enabled - enable/disable force output
+ * @td: DFLL instance
+ * @enable: whether to enable or disable the force output
+ *
+ * Set the enable control for fouce output with fixed value.
+ */
+static void dfll_set_force_output_enabled(struct tegra_dfll *td, bool enable)
+{
+	u32 val = dfll_readl(td, DFLL_OUTPUT_FORCE);
+
+	if (enable)
+		val |= DFLL_OUTPUT_FORCE_ENABLE;
+	else
+		val &= ~DFLL_OUTPUT_FORCE_ENABLE;
+
+	dfll_writel(td, val, DFLL_OUTPUT_FORCE);
+	dfll_wmb(td);
+}
+
+/**
+ * dfll_force_output - force output a fixed value
+ * @td: DFLL instance
+ * @out_sel: value to force output
+ *
+ * Set the fixed value for force output, DFLL will output this value.
+ */
+static int dfll_force_output(struct tegra_dfll *td, unsigned int out_sel)
+{
+	u32 val;
+
+	if (out_sel > OUT_MASK)
+		return -EINVAL;
+
+	val = dfll_set_force_output_value(td, out_sel);
+	if ((td->mode < DFLL_CLOSED_LOOP) &&
+	    !(val & DFLL_OUTPUT_FORCE_ENABLE)) {
+		dfll_set_force_output_enabled(td, true);
+	}
+
+	return 0;
+}
+
 /**
  * dfll_load_lut - load the voltage lookup table
  * @td: struct tegra_dfll *

@@ -539,7 +695,7 @@ static void dfll_load_i2c_lut(struct tegra_dfll *td)
 			lut_index = i;
 
 		val = regulator_list_hardware_vsel(td->vdd_reg,
-						     td->i2c_lut[lut_index]);
+						     td->lut[lut_index]);
 		__raw_writel(val, td->lut_base + i * 4);
 	}
 

@@ -594,24 +750,41 @@ static void dfll_init_out_if(struct tegra_dfll *td)
 {
 	u32 val;
 
-	td->lut_min = 0;
-	td->lut_max = td->i2c_lut_size - 1;
-	td->lut_safe = td->lut_min + 1;
+	td->lut_min = td->lut_bottom;
+	td->lut_max = td->lut_size - 1;
+	td->lut_safe = td->lut_min + (td->lut_min < td->lut_max ? 1 : 0);
+
+	/* clear DFLL_OUTPUT_CFG before setting new value */
+	dfll_writel(td, 0, DFLL_OUTPUT_CFG);
+	dfll_wmb(td);
 
-	dfll_i2c_writel(td, 0, DFLL_OUTPUT_CFG);
 	val = (td->lut_safe << DFLL_OUTPUT_CFG_SAFE_SHIFT) |
-		(td->lut_max << DFLL_OUTPUT_CFG_MAX_SHIFT) |
-		(td->lut_min << DFLL_OUTPUT_CFG_MIN_SHIFT);
-	dfll_i2c_writel(td, val, DFLL_OUTPUT_CFG);
-	dfll_i2c_wmb(td);
+	      (td->lut_max << DFLL_OUTPUT_CFG_MAX_SHIFT) |
+	      (td->lut_min << DFLL_OUTPUT_CFG_MIN_SHIFT);
+	dfll_writel(td, val, DFLL_OUTPUT_CFG);
+	dfll_wmb(td);
 
 	dfll_writel(td, 0, DFLL_OUTPUT_FORCE);
 	dfll_i2c_writel(td, 0, DFLL_INTR_EN);
 	dfll_i2c_writel(td, DFLL_INTR_MAX_MASK | DFLL_INTR_MIN_MASK,
 			DFLL_INTR_STS);
 
-	dfll_load_i2c_lut(td);
-	dfll_init_i2c_if(td);
+	if (td->pmu_if == TEGRA_DFLL_PMU_PWM) {
+		int vinit = td->reg_init_uV;

+
+		/* set initial voltage */
+		if ((vinit >= vmin) && vstep) {
+			unsigned int vsel;
+
+			vsel = DIV_ROUND_UP((vinit - vmin), vstep);
+			dfll_force_output(td, vsel);
+		}
+	} else {
+		dfll_load_i2c_lut(td);
+		dfll_init_i2c_if(td);
+	}
 }
 
 /*

@@ -640,8 +813,8 @@ static int find_lut_index_for_rate(struct tegra_dfll *td, unsigned long rate)
 	uv = dev_pm_opp_get_voltage(opp);
 	dev_pm_opp_put(opp);
 
-	for (i = 0; i < td->i2c_lut_size; i++) {
-		if (regulator_list_voltage(td->vdd_reg, td->i2c_lut[i]) == uv)
+	for (i = td->lut_bottom; i < td->lut_size; i++) {
+		if (td->lut_uv[i] >= uv)