power: avs: Add support for CPR (Core Power Reduction)

CPR (Core Power Reduction) is a technology that reduces core power on a
CPU or other device. It reads voltage settings in efuse from product
test process as initial settings.
Each OPP corresponds to a "corner" that has a range of valid voltages
for a particular frequency. While the device is running at a particular
frequency, CPR monitors dynamic factors such as temperature, etc. and
adjusts the voltage for that frequency accordingly to save power
and meet silicon characteristic requirements.

This driver is based on an RFC by Stephen Boyd[1], which in turn is
based on work by others on codeaurora.org[2].

[1] https://lkml.org/lkml/2015/9/18/833
[2] https://source.codeaurora.org/quic/la/kernel/msm-4.14/tree/drivers/regulator/cpr-regulator.c?h=msm-4.14

Co-developed-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
Signed-off-by: Niklas Cassel <niklas.cassel@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

4 files changed, 1816 insertions, 0 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index cc0a4a8ae06a..b8b0102247f9 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -13667,6 +13667,14 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/opp/qcom-nvmem-cpufreq.txt
 F:	drivers/cpufreq/qcom-cpufreq-nvmem.c
 
+QUALCOMM CORE POWER REDUCTION (CPR) AVS DRIVER
+M:	Niklas Cassel <nks@flawful.org>
+L:	linux-pm@vger.kernel.org
+L:	linux-arm-msm@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/power/avs/qcom,cpr.txt
+F:	drivers/power/avs/qcom-cpr.c
+
 QUALCOMM EMAC GIGABIT ETHERNET DRIVER
 M:	Timur Tabi <timur@kernel.org>
 L:	netdev@vger.kernel.org
diff --git a/drivers/power/avs/Kconfig b/drivers/power/avs/Kconfig
index 089b6244b716..c21882908a66 100644
--- a/drivers/power/avs/Kconfig
+++ b/drivers/power/avs/Kconfig
@@ -12,6 +12,21 @@ menuconfig POWER_AVS
 
 	  Say Y here to enable Adaptive Voltage Scaling class support.
 
+config QCOM_CPR
+	tristate "QCOM Core Power Reduction (CPR) support"
+	depends on POWER_AVS
+	select PM_OPP
+	help
+	  Say Y here to enable support for the CPR hardware found on Qualcomm
+	  SoCs like QCS404.
+
+	  This driver populates CPU OPPs tables and makes adjustments to the
+	  tables based on feedback from the CPR hardware. If you want to do
+	  CPUfrequency scaling say Y here.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called qcom-cpr
+
 config ROCKCHIP_IODOMAIN
 	tristate "Rockchip IO domain support"
 	depends on POWER_AVS && ARCH_ROCKCHIP && OF
diff --git a/drivers/power/avs/Makefile b/drivers/power/avs/Makefile
index a1b8cd453f19..9007d05853e2 100644
--- a/drivers/power/avs/Makefile
+++ b/drivers/power/avs/Makefile
@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0-only
 obj-$(CONFIG_POWER_AVS_OMAP)		+= smartreflex.o
+obj-$(CONFIG_QCOM_CPR)			+= qcom-cpr.o
 obj-$(CONFIG_ROCKCHIP_IODOMAIN)		+= rockchip-io-domain.o
diff --git a/drivers/power/avs/qcom-cpr.c b/drivers/power/avs/qcom-cpr.c
new file mode 100644
index 000000000000..a3187973bbb5
--- /dev/null
+++ b/drivers/power/avs/qcom-cpr.c
@@ -0,0 +1,1792 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2013-2015, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2019, Linaro Limited
+ */
+
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/debugfs.h>
+#include <linux/string.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/bitops.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pm_domain.h>
+#include <linux/pm_opp.h>
+#include <linux/interrupt.h>
+#include <linux/regmap.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regulator/consumer.h>
+#include <linux/clk.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/bitops.h>
+
+/* Register Offsets for RB-CPR and Bit Definitions */
+
+/* RBCPR Version Register */
+#define REG_RBCPR_VERSION		0
+#define RBCPR_VER_2			0x02
+#define FLAGS_IGNORE_1ST_IRQ_STATUS	BIT(0)
+
+/* RBCPR Gate Count and Target Registers */
+#define REG_RBCPR_GCNT_TARGET(n)	(0x60 + 4 * (n))
+
+#define RBCPR_GCNT_TARGET_TARGET_SHIFT	0
+#define RBCPR_GCNT_TARGET_TARGET_MASK	GENMASK(11, 0)
+#define RBCPR_GCNT_TARGET_GCNT_SHIFT	12
+#define RBCPR_GCNT_TARGET_GCNT_MASK	GENMASK(9, 0)
+
+/* RBCPR Timer Control */
+#define REG_RBCPR_TIMER_INTERVAL	0x44
+#define REG_RBIF_TIMER_ADJUST		0x4c
+
+#define RBIF_TIMER_ADJ_CONS_UP_MASK	GENMASK(3, 0)
+#define RBIF_TIMER_ADJ_CONS_UP_SHIFT	0
+#define RBIF_TIMER_ADJ_CONS_DOWN_MASK	GENMASK(3, 0)
+#define RBIF_TIMER_ADJ_CONS_DOWN_SHIFT	4
+#define RBIF_TIMER_ADJ_CLAMP_INT_MASK	GENMASK(7, 0)
+#define RBIF_TIMER_ADJ_CLAMP_INT_SHIFT	8
+
+/* RBCPR Config Register */
+#define REG_RBIF_LIMIT			0x48
+#define RBIF_LIMIT_CEILING_MASK		GENMASK(5, 0)
+#define RBIF_LIMIT_CEILING_SHIFT	6
+#define RBIF_LIMIT_FLOOR_BITS		6
+#define RBIF_LIMIT_FLOOR_MASK		GENMASK(5, 0)
+
+#define RBIF_LIMIT_CEILING_DEFAULT	RBIF_LIMIT_CEILING_MASK
+#define RBIF_LIMIT_FLOOR_DEFAULT	0
+
+#define REG_RBIF_SW_VLEVEL		0x94
+#define RBIF_SW_VLEVEL_DEFAULT		0x20
+
+#define REG_RBCPR_STEP_QUOT		0x80
+#define RBCPR_STEP_QUOT_STEPQUOT_MASK	GENMASK(7, 0)
+#define RBCPR_STEP_QUOT_IDLE_CLK_MASK	GENMASK(3, 0)
+#define RBCPR_STEP_QUOT_IDLE_CLK_SHIFT	8
+
+/* RBCPR Control Register */
+#define REG_RBCPR_CTL			0x90
+
+#define RBCPR_CTL_LOOP_EN			BIT(0)
+#define RBCPR_CTL_TIMER_EN			BIT(3)
+#define RBCPR_CTL_SW_AUTO_CONT_ACK_EN		BIT(5)
+#define RBCPR_CTL_SW_AUTO_CONT_NACK_DN_EN	BIT(6)
+#define RBCPR_CTL_COUNT_MODE			BIT(10)
+#define RBCPR_CTL_UP_THRESHOLD_MASK	GENMASK(3, 0)
+#define RBCPR_CTL_UP_THRESHOLD_SHIFT	24
+#define RBCPR_CTL_DN_THRESHOLD_MASK	GENMASK(3, 0)
+#define RBCPR_CTL_DN_THRESHOLD_SHIFT	28
+
+/* RBCPR Ack/Nack Response */
+#define REG_RBIF_CONT_ACK_CMD		0x98
+#define REG_RBIF_CONT_NACK_CMD		0x9c
+
+/* RBCPR Result status Register */
+#define REG_RBCPR_RESULT_0		0xa0
+
+#define RBCPR_RESULT0_BUSY_SHIFT	19
+#define RBCPR_RESULT0_BUSY_MASK		BIT(RBCPR_RESULT0_BUSY_SHIFT)
+#define RBCPR_RESULT0_ERROR_LT0_SHIFT	18
+#define RBCPR_RESULT0_ERROR_SHIFT	6
+#define RBCPR_RESULT0_ERROR_MASK	GENMASK(11, 0)
+#define RBCPR_RESULT0_ERROR_STEPS_SHIFT	2
+#define RBCPR_RESULT0_ERROR_STEPS_MASK	GENMASK(3, 0)
+#define RBCPR_RESULT0_STEP_UP_SHIFT	1
+
+/* RBCPR Interrupt Control Register */
+#define REG_RBIF_IRQ_EN(n)		(0x100 + 4 * (n))
+#define REG_RBIF_IRQ_CLEAR		0x110
+#define REG_RBIF_IRQ_STATUS		0x114
+
+#define CPR_INT_DONE		BIT(0)
+#define CPR_INT_MIN		BIT(1)
+#define CPR_INT_DOWN		BIT(2)
+#define CPR_INT_MID		BIT(3)
+#define CPR_INT_UP		BIT(4)
+#define CPR_INT_MAX		BIT(5)
+#define CPR_INT_CLAMP		BIT(6)
+#define CPR_INT_ALL	(CPR_INT_DONE | CPR_INT_MIN | CPR_INT_DOWN | \
+			CPR_INT_MID | CPR_INT_UP | CPR_INT_MAX | CPR_INT_CLAMP)
+#define CPR_INT_DEFAULT	(CPR_INT_UP | CPR_INT_DOWN)
+
+#define CPR_NUM_RING_OSC	8
+
+/* CPR eFuse parameters */
+#define CPR_FUSE_TARGET_QUOT_BITS_MASK	GENMASK(11, 0)
+
+#define CPR_FUSE_MIN_QUOT_DIFF		50
+
+#define FUSE_REVISION_UNKNOWN		(-1)
+
+enum voltage_change_dir {
+	NO_CHANGE,
+	DOWN,
+	UP,
+};
+
+struct cpr_fuse {
+	char *ring_osc;
+	char *init_voltage;
+	char *quotient;
+	char *quotient_offset;
+};
+
+struct fuse_corner_data {
+	int ref_uV;
+	int max_uV;
+	int min_uV;
+	int max_volt_scale;
+	int max_quot_scale;
+	/* fuse quot */
+	int quot_offset;
+	int quot_scale;
+	int quot_adjust;
+	/* fuse quot_offset */
+	int quot_offset_scale;
+	int quot_offset_adjust;
+};
+
+struct cpr_fuses {
+	int init_voltage_step;
+	int init_voltage_width;
+	struct fuse_corner_data *fuse_corner_data;
+};
+
+struct corner_data {
+	unsigned int fuse_corner;
+	unsigned long freq;
+};
+
+struct cpr_desc {
+	unsigned int num_fuse_corners;
+	int min_diff_quot;
+	int *step_quot;
+
+	unsigned int		timer_delay_us;
+	unsigned int		timer_cons_up;
+	unsigned int		timer_cons_down;
+	unsigned int		up_threshold;
+	unsigned int		down_threshold;
+	unsigned int		idle_clocks;
+	unsigned int		gcnt_us;
+	unsigned int		vdd_apc_step_up_limit;
+	unsigned int		vdd_apc_step_down_limit;
+	unsigned int		clamp_timer_interval;
+
+	struct cpr_fuses cpr_fuses;
+	bool reduce_to_fuse_uV;
+	bool reduce_to_corner_uV;
+};
+
+struct acc_desc {
+	unsigned int	enable_reg;
+	u32		enable_mask;
+
+	struct reg_sequence	*config;
+	struct reg_sequence	*settings;
+	int			num_regs_per_fuse;
+};
+
+struct cpr_acc_desc {
+	const struct cpr_desc *cpr_desc;
+	const struct acc_desc *acc_desc;
+};
+
+struct fuse_corner {
+	int min_uV;
+	int max_uV;
+	int uV;
+	int quot;
+	int step_quot;
+	const struct reg_sequence *accs;
+	int num_accs;
+	unsigned long max_freq;
+	u8 ring_osc_idx;
+};
+
+struct corner {
+	int min_uV;
+	int max_uV;
+	int uV;
+	int last_uV;
+	int quot_adjust;
+	u32 save_ctl;
+	u32 save_irq;
+	unsigned long freq;
+	struct fuse_corner *fuse_corner;
+};
+
+struct cpr_drv {
+	unsigned int		num_corners;
+	unsigned int		ref_clk_khz;
+
+	struct generic_pm_domain pd;
+	struct device		*dev;
+	struct device		*attached_cpu_dev;
+	struct mutex		lock;
+	void __iomem		*base;
+	struct corner		*corner;
+	struct regulator	*vdd_apc;
+	struct clk		*cpu_clk;
+	struct regmap		*tcsr;
+	bool			loop_disabled;
+	u32			gcnt;
+	unsigned long		flags;
+
+	struct fuse_corner	*fuse_corners;
+	struct corner		*corners;
+
+	const struct cpr_desc *desc;
+	const struct acc_desc *acc_desc;
+	const struct cpr_fuse *cpr_fuses;
+
+	struct dentry *debugfs;
+};
+
+static bool cpr_is_allowed(struct cpr_drv *drv)
+{
+	return !drv->loop_disabled;
+}
+
+static void cpr_write(struct cpr_drv *drv, u32 offset, u32 value)
+{
+	writel_relaxed(value, drv->base + offset);
+}
+
+static u32 cpr_read(struct cpr_drv *drv, u32 offset)
+{
+	return readl_relaxed(drv->base + offset);
+}
+
+static void
+cpr_masked_write(struct cpr_drv *drv, u32 offset, u32 mask, u32 value)
+{
+	u32 val;
+
+	val = readl_relaxed(drv->base + offset);
+	val &= ~mask;
+	val |= value & mask;
+	writel_relaxed(val, drv->base + offset);
+}
+
+static void cpr_irq_clr(struct cpr_drv *drv)
+{
+	cpr_write(drv, REG_RBIF_IRQ_CLEAR, CPR_INT_ALL);
+}
+
+static void cpr_irq_clr_nack(struct cpr_drv *drv)
+{
+	cpr_irq_clr(drv);
+	cpr_write(drv, REG_RBIF_CONT_NACK_CMD, 1);
+}
+
+static void cpr_irq_clr_ack(struct cpr_drv *drv)
+{
+	cpr_irq_clr(drv);
+	cpr_write(drv, REG_RBIF_CONT_ACK_CMD, 1);
+}
+
+static void cpr_irq_set(struct cpr_drv *drv, u32 int_bits)
+{
+	cpr_write(drv, REG_RBIF_IRQ_EN(0), int_bits);
+}
+
+static void cpr_ctl_modify(struct cpr_drv *drv, u32 mask, u32 value)
+{
+	cpr_masked_write(drv, REG_RBCPR_CTL, mask, value);
+}
+
+static void cpr_ctl_enable(struct cpr_drv *drv, struct corner *corner)
+{
+	u32 val, mask;
+	const struct cpr_desc *desc = drv->desc;
+
+	/* Program Consecutive Up & Down */
+	val = desc->timer_cons_down << RBIF_TIMER_ADJ_CONS_DOWN_SHIFT;
+	val |= desc->timer_cons_up << RBIF_TIMER_ADJ_CONS_UP_SHIFT;
+	mask = RBIF_TIMER_ADJ_CONS_UP_MASK | RBIF_TIMER_ADJ_CONS_DOWN_MASK;
+	cpr_masked_write(drv, REG_RBIF_TIMER_ADJUST, mask, val);
+	cpr_masked_write(drv, REG_RBCPR_CTL,
+			 RBCPR_CTL_SW_AUTO_CONT_NACK_DN_EN |
+			 RBCPR_CTL_SW_AUTO_CONT_ACK_EN,
+			 corner->save_ctl);
+	cpr_irq_set(drv, corner->save_irq);
+
+	if (cpr_is_allowed(drv) && corner->max_uV > corner->min_uV)
+		val = RBCPR_CTL_LOOP_EN;
+	else
+		val = 0;
+	cpr_ctl_modify(drv, RBCPR_CTL_LOOP_EN, val);
+}
+
+static void cpr_ctl_disable(struct cpr_drv *drv)
+{
+	cpr_irq_set(drv, 0);
+	cpr_ctl_modify(drv, RBCPR_CTL_SW_AUTO_CONT_NACK_DN_EN |
+		       RBCPR_CTL_SW_AUTO_CONT_ACK_EN, 0);
+	cpr_masked_write(drv, REG_RBIF_TIMER_ADJUST,
+			 RBIF_TIMER_ADJ_CONS_UP_MASK |
+			 RBIF_TIMER_ADJ_CONS_DOWN_MASK, 0);
+	cpr_irq_clr(drv);
+	cpr_write(drv, REG_RBIF_CONT_ACK_CMD, 1);
+	cpr_write(drv, REG_RBIF_CONT_NACK_CMD, 1);
+	cpr_ctl_modify(drv, RBCPR_CTL_LOOP_EN, 0);
+}
+
+static bool cpr_ctl_is_enabled(struct cpr_drv *drv)
+{
+	u32 reg_val;
+
+	reg_val = cpr_read(drv, REG_RBCPR_CTL);
+	return reg_val & RBCPR_CTL_LOOP_EN;
+}
+
+static bool cpr_ctl_is_busy(struct cpr_drv *drv)
+{
+	u32 reg_val;
+
+	reg_val = cpr_read(drv, REG_RBCPR_RESULT_0);
+	return reg_val & RBCPR_RESULT0_BUSY_MASK;
+}
+
+static void cpr_corner_save(struct cpr_drv *drv, struct corner *corner)
+{
+	corner->save_ctl = cpr_read(drv, REG_RBCPR_CTL);
+	corner->save_irq = cpr_read(drv, REG_RBIF_IRQ_EN(0));
+}
+
+static void cpr_corner_restore(struct cpr_drv *drv, struct corner *corner)
+{
+	u32 gcnt, ctl, irq, ro_sel, step_quot;
+	struct fuse_corner *fuse = corner->fuse_corner;
+	const struct cpr_desc *desc = drv->desc;
+	int i;
+
+	ro_sel = fuse->ring_osc_idx;
+	gcnt = drv->gcnt;
+	gcnt |= fuse->quot - corner->quot_adjust;
+
+	/* Program the step quotient and idle clocks */
+	step_quot = desc->idle_clocks << RBCPR_STEP_QUOT_IDLE_CLK_SHIFT;
+	step_quot |= fuse->step_quot & RBCPR_STEP_QUOT_STEPQUOT_MASK;
+	cpr_write(drv, REG_RBCPR_STEP_QUOT, step_quot);
+
+	/* Clear the target quotient value and gate count of all ROs */
+	for (i = 0; i < CPR_NUM_RING_OSC; i++)
+		cpr_write(drv, REG_RBCPR_GCNT_TARGET(i), 0);
+
+	cpr_write(drv, REG_RBCPR_GCNT_TARGET(ro_sel), gcnt);
+	ctl = corner->save_ctl;
+	cpr_write(drv, REG_RBCPR_CTL, ctl);
+	irq = corner->save_irq;
+	cpr_irq_set(drv, irq);
+	dev_dbg(drv->dev, "gcnt = %#08x, ctl = %#08x, irq = %#08x\n", gcnt,
+		ctl, irq);
+}
+
+static void cpr_set_acc(struct regmap *tcsr, struct fuse_corner *f,
+			struct fuse_corner *end)
+{
+	if (f == end)
+		return;
+
+	if (f < end) {
+		for (f += 1; f <= end; f++)
+			regmap_multi_reg_write(tcsr, f->accs, f->num_accs);
+	} else {
+		for (f -= 1; f >= end; f--)
+			regmap_multi_reg_write(tcsr, f->accs, f->num_accs);
+	}
+}
+
+static int cpr_pre_voltage(struct cpr_drv *drv,
+			   struct fuse_corner *fuse_corner,
+			   enum voltage_change_dir dir)
+{
+	struct fuse_corner *prev_fuse_corner = drv->corner->fuse_corner;
+
+	if (drv->tcsr && dir == DOWN)
+		cpr_set_acc(drv->tcsr, prev_fuse_corner, fuse_corner);
+
+	return 0;
+}
+
+static int cpr_post_voltage(struct cpr_drv *drv,
+			    struct fuse_corner *fuse_corner,
+			    enum voltage_change_dir dir)
+{
+	struct fuse_corner *prev_fuse_corner = drv->corner->fuse_corner;
+
+	if (drv->tcsr && dir == UP)
+		cpr_set_acc(drv->tcsr, prev_fuse_corner, fuse_corner);
+
+	return 0;
+}
+
+static int cpr_scale_voltage(struct cpr_drv *drv, struct corner *corner,
+			     int new_uV, enum voltage_change_dir dir)
+{
+	int ret;
+	struct fuse_corner *fuse_corner = corner->fuse_corner;
+
+	ret = cpr_pre_voltage(drv, fuse_corner, dir);
+	if (ret)
+		return ret;
+
+	ret = regulator_set_voltage(drv->vdd_apc, new_uV, new_uV);
+	if (ret) {
+		dev_err_ratelimited(drv->dev, "failed to set apc voltage %d\n",
+				    new_uV);
+		return ret;
+	}
+
+	ret = cpr_post_voltage(drv, fuse_corner, dir);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static unsigned int cpr_get_cur_perf_state(struct cpr_drv *drv)
+{
+	return drv->corner ? drv->corner - drv->corners + 1 : 0;
+}
+
+static int cpr_scale(struct cpr_drv *drv, enum voltage_change_dir dir)
+{
+	u32 val, error_steps, reg_mask;
+	int last_uV, new_uV, step_uV, ret;
+	struct corner *corner;
+	const struct cpr_desc *desc = drv->desc;
+
+	if (dir != UP && dir != DOWN)
+		return 0;
+
+	step_uV = regulator_get_linear_step(drv->vdd_apc);
+	if (!step_uV)
+		return -EINVAL;
+
+	corner = drv->corner;
+
+	val = cpr_read(drv, REG_RBCPR_RESULT_0);
+
+	error_steps = val >> RBCPR_RESULT0_ERROR_STEPS_SHIFT;
+	error_steps &= RBCPR_RESULT0_ERROR_STEPS_MASK;
+	last_uV = corner->last_uV;
+
+	if (dir == UP) {
+		if (desc->clamp_timer_interval &&
+		    error_steps < desc->up_threshold) {
+			/*
+			 * Handle the case where another measurement started
+			 * after the interrupt was triggered due to a core
+			 * exiting from power collapse.
+			 */
+			error_steps = max(desc->up_threshold,
+					  desc->vdd_apc_step_up_limit);
+		}
+
+		if (last_uV >= corner->max_uV) {
+			cpr_irq_clr_nack(drv);
+
+			/* Maximize the UP threshold */
+			reg_mask = RBCPR_CTL_UP_THRESHOLD_MASK;
+			reg_mask <<= RBCPR_CTL_UP_THRESHOLD_SHIFT;
+			val = reg_mask;
+			cpr_ctl_modify(drv, reg_mask, val);
+
+			/* Disable UP interrupt */
+			cpr_irq_set(drv, CPR_INT_DEFAULT & ~CPR_INT_UP);
+
+			return 0;
+		}
+
+		if (error_steps > desc->vdd_apc_step_up_limit)
+			error_steps = desc->vdd_apc_step_up_limit;
+
+		/* Calculate new voltage */
+		new_uV = last_uV + error_steps * step_uV;
+		new_uV = min(new_uV, corner->max_uV);
+
+		dev_dbg(drv->dev,
+			"UP: -> new_uV: %d last_uV: %d perf state: %u\n",
+			new_uV, last_uV, cpr_get_cur_perf_state(drv));
+	} else if (dir == DOWN) {
+		if (desc->clamp_timer_interval &&
+		    error_steps < desc->down_threshold) {
+			/*
+			 * Handle the case where another measurement started
+			 * after the interrupt was triggered due to a core
+			 * exiting from power collapse.
+			 */
+			error_steps = max(desc->down_threshold,
+					  desc->vdd_apc_step_down_limit);
+		}
+
+		if (last_uV <= corner->min_uV) {
+			cpr_irq_clr_nack(drv);
+
+			/* Enable auto nack down */
+			reg_mask = RBCPR_CTL_SW_AUTO_CONT_NACK_DN_EN;
+			val = RBCPR_CTL_SW_AUTO_CONT_NACK_DN_EN;
+
+			cpr_ctl_modify(drv, reg_mask, val);
+
+			/* Disable DOWN interrupt */
+			cpr_irq_set(drv, CPR_INT_DEFAULT & ~CPR_INT_DOWN);
+
+			return 0;
+		}
+
+		if (error_steps > desc->vdd_apc_step_down_limit)
+			error_steps = desc->vdd_apc_step_down_limit;
+
+		/* Calculate new voltage */
+		new_uV = last_uV - error_steps * step_uV;
+		new_uV = max(new_uV, corner->min_uV);
+
+		dev_dbg(drv->dev,
+			"DOWN: -> new_uV: %d last_uV: %d perf state: %u\n",
+			new_uV, last_uV, cpr_get_cur_perf_state(drv));
+	}
+
+	ret = cpr_scale_voltage(drv, corner, new_uV, dir);
+	if (ret) {
+		cpr_irq_clr_nack(drv);
+		return ret;
+	}
+	drv->corner->last_uV = new_uV;
+
+	if (dir == UP) {
+		/* Disable auto nack down */
+		reg_mask = RBCPR_CTL_SW_AUTO_CONT_NACK_DN_EN;
+		val = 0;
+	} else if (dir == DOWN) {
+		/* Restore default threshold for UP */
+		reg_mask = RBCPR_CTL_UP_THRESHOLD_MASK;
+		reg_mask <<= RBCPR_CTL_UP_THRESHOLD_SHIFT;
+		val = desc->up_threshold;
+		val <<= RBCPR_CTL_UP_THRESHOLD_SHIFT;
+	}
+
+	cpr_ctl_modify(drv, reg_mask, val);
+
+	/* Re-enable default interrupts */
+	cpr_irq_set(drv, CPR_INT_DEFAULT);
+
+	/* Ack */
+	cpr_irq_clr_ack(drv);
+
+	return 0;
+}
+
+static irqreturn_t cpr_irq_handler(int irq, void *dev)
+{
+	struct cpr_drv *drv = dev;
+	const struct cpr_desc *desc = drv->desc;
+	irqreturn_t ret = IRQ_HANDLED;
+	u32 val;
+
+	mutex_lock(&drv->lock);
+
+	val = cpr_read(drv, REG_RBIF_IRQ_STATUS);
+	if (drv->flags & FLAGS_IGNORE_1ST_IRQ_STATUS)
+		val = cpr_read(drv, REG_RBIF_IRQ_STATUS);
+
+	dev_dbg(drv->dev, "IRQ_STATUS = %#02x\n", val);
+
+	if (!cpr_ctl_is_enabled(drv)) {
+		dev_dbg(drv->dev, "CPR is disabled\n");
+		ret = IRQ_NONE;
+	} else if (cpr_ctl_is_busy(drv) && !desc->clamp_timer_interval) {
+		dev_dbg(drv->dev, "CPR measurement is not ready\n");
+	} else if (!cpr_is_allowed(drv)) {
+		val = cpr_read(drv, REG_RBCPR_CTL);
+		dev_err_ratelimited(drv->dev,
+				    "Interrupt broken? RBCPR_CTL = %#02x\n",
+				    val);
+		ret = IRQ_NONE;
+	} else {
+		/*
+		 * Following sequence of handling is as per each IRQ's
+		 * priority
+		 */
+		if (val & CPR_INT_UP) {
+			cpr_scale(drv, UP);
+		} else if (val & CPR_INT_DOWN) {
+			cpr_scale(drv, DOWN);
+		} else if (val & CPR_INT_MIN) {
+			cpr_irq_clr_nack(drv);
+		} else if (val & CPR_INT_MAX) {
+			cpr_irq_clr_nack(drv);
+		} else if (val & CPR_INT_MID) {
+			/* RBCPR_CTL_SW_AUTO_CONT_ACK_EN is enabled */
+			dev_dbg(drv->dev, "IRQ occurred for Mid Flag\n");
+		} else {
+			dev_dbg(drv->dev,
+				"IRQ occurred for unknown flag (%#08x)\n", val);
+		}
+
+		/* Save register values for the corner */
+		cpr_corner_save(drv, drv->corner);
+	}
+
+	mutex_unlock(&drv->lock);
+
+	return ret;
+}
+
+static int cpr_enable(struct cpr_drv *drv)
+{
+	int ret;
+
+	ret = regulator_enable(drv->vdd_apc);
+	if (ret)
+		return ret;
+
+	mutex_lock(&drv->lock);
+
+	if (cpr_is_allowed(drv) && drv->corner) {
+		cpr_irq_clr(drv);
+		cpr_corner_restore(drv, drv->corner);
+		cpr_ctl_enable(drv, drv->corner);
+	}
+
+	mutex_unlock(&drv->lock);
+
+	return 0;
+}
+
+static int cpr_disable(struct cpr_drv *drv)
+{
+	int ret;
+
+	mutex_lock(&drv->lock);
+
+	if (cpr_is_allowed(drv)) {
+		cpr_ctl_disable(drv);
+		cpr_irq_clr(drv);
+	}
+
+	mutex_unlock(&drv->lock);
+
+	ret = regulator_disable(drv->vdd_apc);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int cpr_config(struct cpr_drv *drv)
+{
+	int i;
+	u32 val, gcnt;
+	struct corner *corner;
+	const struct cpr_desc *desc = drv->desc;
+
+	/* Disable interrupt and CPR */
+	cpr_write(drv, REG_RBIF_IRQ_EN(0), 0);
+	cpr_write(drv, REG_RBCPR_CTL, 0);
+
+	/* Program the default HW ceiling, floor and vlevel */
+	val = (RBIF_LIMIT_CEILING_DEFAULT & RBIF_LIMIT_CEILING_MASK)
+		<< RBIF_LIMIT_CEILING_SHIFT;
+	val |= RBIF_LIMIT_FLOOR_DEFAULT & RBIF_LIMIT_FLOOR_MASK;
+	cpr_write(drv, REG_RBIF_LIMIT, val);
+	cpr_write(drv, REG_RBIF_SW_VLEVEL, RBIF_SW_VLEVEL_DEFAULT);
+
+	/*
+	 * Clear the target quotient value and gate count of all
+	 * ring oscillators
+	 */
+	for (i = 0; i < CPR_NUM_RING_OSC; i++)
+		cpr_write(drv, REG_RBCPR_GCNT_TARGET(i), 0);
+
+	/* Init and save gcnt */
+	gcnt = (drv->ref_clk_khz * desc->gcnt_us) / 1000;
+	gcnt = gcnt & RBCPR_GCNT_TARGET_GCNT_MASK;
+	gcnt <<= RBCPR_GCNT_TARGET_GCNT_SHIFT;
+	drv->gcnt = gcnt;
+
+	/* Program the delay count for the timer */
+	val = (drv->ref_clk_khz * desc->timer_delay_us) / 1000;
+	cpr_write(drv, REG_RBCPR_TIMER_INTERVAL, val);
+	dev_dbg(drv->dev, "Timer count: %#0x (for %d us)\n", val,
+		desc->timer_delay_us);
+
+	/* Program Consecutive Up & Down */
+	val = desc->timer_cons_down << RBIF_TIMER_ADJ_CONS_DOWN_SHIFT;
+	val |= desc->timer_cons_up << RBIF_TIMER_ADJ_CONS_UP_SHIFT;
+	val |= desc->clamp_timer_interval << RBIF_TIMER_ADJ_CLAMP_INT_SHIFT;
+	cpr_write(drv, REG_RBIF_TIMER_ADJUST, val);
+
+	/* Program the control register */
+	val = desc->up_threshold << RBCPR_CTL_UP_THRESHOLD_SHIFT;
+	val |= desc->down_threshold << RBCPR_CTL_DN_THRESHOLD_SHIFT;
+	val |= RBCPR_CTL_TIMER_EN | RBCPR_CTL_COUNT_MODE;
+	val |= RBCPR_CTL_SW_AUTO_CONT_ACK_EN;
+	cpr_write(drv, REG_RBCPR_CTL, val);
+
+	for (i = 0; i < drv->num_corners; i++) {
+		corner = &drv->corners[i];
+		corner->save_ctl = val;
+		corner->save_irq = CPR_INT_DEFAULT;
+	}
+
+	cpr_irq_set(drv, CPR_INT_DEFAULT);
+
+	val = cpr_read(drv, REG_RBCPR_VERSION);
+	if (val <= RBCPR_VER_2)
+		drv->flags |= FLAGS_IGNORE_1ST_IRQ_STATUS;
+
+	return 0;
+}
+
+static int cpr_set_performance_state(struct generic_pm_domain *domain,
+				     unsigned int state)
+{
+	struct cpr_drv *drv = container_of(domain, struct cpr_drv, pd);
+	struct corner *corner, *end;
+	enum voltage_change_dir dir;
+	int ret = 0, new_uV;
+
+	mutex_lock(&drv->lock);
+
+	dev_dbg(drv->dev, "%s: setting perf state: %u (prev state: %u)\n",
+		__func__, state, cpr_get_cur_perf_state(drv));
+
+	/*
+	 * Determine new corner we're going to.
+	 * Remove one since lowest performance state is 1.
+	 */
+	corner = drv->corners + state - 1;
+	end = &drv->corners[drv->num_corners - 1];
+	if (corner > end || corner < drv->corners) {
+		ret = -EINVAL;
+		goto unlock;
+	}
+
+	/* Determine direction */
+	if (drv->corner > corner)
+		dir = DOWN;
+	else if (drv->corner < corner)
+		dir = UP;
+	else
+		dir = NO_CHANGE;
+
+	if (cpr_is_allowed(drv))
+		new_uV = corner->last_uV;
+	else
+		new_uV = corner->uV;
+
+	if (cpr_is_allowed(drv))
+		cpr_ctl_disable(drv);
+
+	ret = cpr_scale_voltage(drv, corner, new_uV, dir);
+	if (ret)
+		goto unlock;
+
+	if (cpr_is_allowed(drv)) {
+		cpr_irq_clr(drv);
+		if (drv->corner != corner)
+			cpr_corner_restore(drv, corner);
+		cpr_ctl_enable(drv, corner);
+	}
+
+	drv->corner = corner;
+
+unlock:
+	mutex_unlock(&drv->lock);
+
+	return ret;
+}
+
+static int cpr_read_efuse(struct device *dev, const char *cname, u32 *data)
+{
+	struct nvmem_cell *cell;
+	ssize_t len;
+	char *ret;
+	int i;
+
+	*data = 0;
+
+	cell = nvmem_cell_get(dev, cname);
+	if (IS_ERR(cell)) {
+		if (PTR_ERR(cell) != -EPROBE_DEFER)
+			dev_err(dev, "undefined cell %s\n", cname);
+		return PTR_ERR(cell);
+	}
+
+	ret = nvmem_cell_read(cell, &len);
+	nvmem_cell_put(cell);
+	if (IS_ERR(ret)) {
+		dev_err(dev, "can't read cell %s\n", cname);
+		return PTR_ERR(ret);
+	}
+
+	for (i = 0; i < len; i++)
+		*data |= ret[i] << (8 * i);
+
+	kfree(ret);
+	dev_dbg(dev, "efuse read(%s) = %x, bytes %ld\n", cname, *data, len);
+
+	return 0;
+}
+
+static int
+cpr_populate_ring_osc_idx(struct cpr_drv *drv)
+{
+	struct fuse_corner *fuse = drv->fuse_corners;
+	struct fuse_corner *end = fuse + drv->desc->num_fuse_corners;
+	const struct cpr_fuse *fuses = drv->cpr_fuses;
+	u32 data;
+	int ret;
+
+	for (; fuse < end; fuse++, fuses++) {
+		ret = cpr_read_efuse(drv->dev, fuses->ring_osc,
+				     &data);
+		if (ret)
+			return ret;
+		fuse->ring_osc_idx = data;
+	}
+
+	return 0;
+}
+
+static int cpr_read_fuse_uV(const struct cpr_desc *desc,
+			    const struct fuse_corner_data *fdata,
+			    const char *init_v_efuse,
+			    int step_volt,
+			    struct cpr_drv *drv)
+{
+	int step_size_uV, steps, uV;
+	u32 bits = 0;
+	int ret;
+
+	ret = cpr_read_efuse(drv->dev, init_v_efuse, &bits);
+	if (ret)
+		return ret;
+
+	steps = bits & ~BIT(desc->cpr_fuses.init_voltage_width - 1);
+	/* Not two's complement.. instead highest bit is sign bit */
+	if (bits & BIT(desc->cpr_fuses.init_voltage_width - 1))
+		steps = -steps;
+
+	step_size_uV = desc->cpr_fuses.init_voltage_step;
+
+	uV = fdata->ref_uV + steps * step_size_uV;
+	return DIV_ROUND_UP(uV, step_volt) * step_volt;
+}
+
+static int cpr_fuse_corner_init(struct cpr_drv *drv)
+{
+	const struct cpr_desc *desc = drv->desc;
+	const struct cpr_fuse *fuses = drv->cpr_fuses;
+	const struct acc_desc *acc_desc = drv->acc_desc;
+	int i;
+	unsigned int step_volt;
+	struct fuse_corner_data *fdata;
+	struct fuse_corner *fuse, *end, *prev;
+	int uV;
+	const struct reg_sequence *accs;
+	int ret;
+
+	accs = acc_desc->settings;
+
+	step_volt = regulator_get_linear_step(drv->vdd_apc);
+	if (!step_volt)
+		return -EINVAL;
+
+	/* Populate fuse_corner members */
+	fuse = drv->fuse_corners;
+	end = &fuse[desc->num_fuse_corners - 1];
+	fdata = desc->cpr_fuses.fuse_corner_data;
+
+	for (i = 0, prev = NULL; fuse <= end; fuse++, fuses++, i++, fdata++) {
+		/*
+		 * Update SoC voltages: platforms might choose a different
+		 * regulators than the one used to characterize the algorithms
+		 * (ie, init_voltage_step).
+		 */
+		fdata->min_uV = roundup(fdata->min_uV, step_volt);
+		fdata->max_uV = roundup(fdata->max_uV, step_volt);
+
+		/* Populate uV */
+		uV = cpr_read_fuse_uV(desc, fdata, fuses->init_voltage,
+				      step_volt, drv);
+		if (uV < 0)
+			return ret;
+
+		fuse->min_uV = fdata->min_uV;
+		fuse->max_uV = fdata->max_uV;
+		fuse->uV = clamp(uV, fuse->min_uV, fuse->max_uV);
+
+		if (fuse == end) {
+			/*
+			 * Allow the highest fuse corner's PVS voltage to
+			 * define the ceiling voltage for that corner in order
+			 * to support SoC's in which variable ceiling values
+			 * are required.
+			 */
+			end->max_uV = max(end->max_uV, end->uV);
+		}
+
+		/* Populate target quotient by scaling */
+		ret = cpr_read_efuse(drv->dev, fuses->quotient, &fuse->quot);
+		if (ret)
+			return ret;
+
+		fuse->quot *= fdata->quot_scale;
+		fuse->quot += fdata->quot_offset;
+		fuse->quot += fdata->quot_adjust;
+		fuse->step_quot = desc->step_quot[fuse->ring_osc_idx];
+
+		/* Populate acc settings */
+		fuse->accs = accs;
+		fuse->num_accs = acc_desc->num_regs_per_fuse;
+		accs += acc_desc->num_regs_per_fuse;
+	}
+
+	/*
+	 * Restrict all fuse corner PVS voltages based upon per corner
+	 * ceiling and floor voltages.
+	 */
+	for (fuse = drv->fuse_corners, i = 0; fuse <= end; fuse++, i++) {
+		if (fuse->uV > fuse->max_uV)
+			fuse->uV = fuse->max_uV;
+		else if (fuse->uV < fuse->min_uV)
+			fuse->uV = fuse->min_uV;
+
+		ret = regulator_is_supported_voltage(drv->vdd_apc,
+						     fuse->min_uV,
+						     fuse->min_uV);
+		if (!ret) {
+			dev_err(drv->dev,
+				"min uV: %d (fuse corner: %d) not supported by regulator\n",
+				fuse->min_uV, i);
+			return -EINVAL;
+		}
+
+		ret = regulator_is_supported_voltage(drv->vdd_apc,
+						     fuse->max_uV,
+						     fuse->max_uV);
+		if (!ret) {
+			dev_err(drv->dev,
+				"max uV: %d (fuse corner: %d) not supported by regulator\n",
+				fuse->max_uV, i);
+			return -EINVAL;
+		}
+
+		dev_dbg(drv->dev,
+			"fuse corner %d: [%d %d %d] RO%hhu quot %d squot %d\n",
+			i, fuse->min_uV, fuse->uV, fuse->max_uV,
+			fuse->ring_osc_idx, fuse->quot, fuse->step_quot);
+	}
+
+	return 0;
+}
+
+static int cpr_calculate_scaling(const char *quot_offset,
+				 struct cpr_drv *drv,
+				 const struct fuse_corner_data *fdata,
+				 const struct corner *corner)
+{
+	u32 quot_diff = 0;
+	unsigned long freq_diff;
+	int scaling;
+	const struct fuse_corner *fuse, *prev_fuse;
+	int ret;
+
+	fuse = corner->fuse_corner;
+	prev_fuse = fuse - 1;
+
+	if (quot_offset) {
+		ret = cpr_read_efuse(drv->dev, quot_offset, &quot_diff);
+		if (ret)
+			return ret;
+
+		quot_diff *= fdata->quot_offset_scale;
+		quot_diff += fdata->quot_offset_adjust;
+	} else {
+		quot_diff = fuse->quot - prev_fuse->quot;
+	}
+
+	freq_diff = fuse->max_freq - prev_fuse->max_freq;
+	freq_diff /= 1000000; /* Convert to MHz */
+	scaling = 1000 * quot_diff / freq_diff;
+	return min(scaling, fdata->max_quot_scale);
+}
+
+static int cpr_interpolate(const struct corner *corner, int step_volt,
+			   const struct fuse_corner_data *fdata)
+{
+	unsigned long f_high, f_low, f_diff;
+	int uV_high, uV_low, uV;
+	u64 temp, temp_limit;
+	const struct fuse_corner *fuse, *prev_fuse;
+
+	fuse = corner->fuse_corner;
+	prev_fuse = fuse - 1;
+
+	f_high = fuse->max_freq;
+	f_low = prev_fuse->max_freq;
+	uV_high = fuse->uV;
+	uV_low = prev_fuse->uV;
+	f_diff = fuse->max_freq - corner->freq;
+
+	/*
+	 * Don't interpolate in the wrong direction. This could happen
+	 * if the adjusted fuse voltage overlaps with the previous fuse's
+	 * adjusted voltage.
+	 */
+	if (f_high <= f_low || uV_high <= uV_low || f_high <= corner->freq)
+		return corner->uV;
+
+	temp = f_diff * (uV_high - uV_low);
+	do_div(temp, f_high - f_low);
+
+	/*
+	 * max_volt_scale has units of uV/MHz while freq values
+	 * have units of Hz.  Divide by 1000000 to convert to.
+	 */
+	temp_limit = f_diff * fdata->max_volt_scale;
+	do_div(temp_limit, 1000000);
+
+	uV = uV_high - min(temp, temp_limit);
+	return roundup(uV, step_volt);
+}
+
+static unsigned int cpr_get_fuse_corner(struct dev_pm_opp *opp)
+{
+	struct device_node *np;
+	unsigned int fuse_corner = 0;
+
+	np = dev_pm_opp_get_of_node(opp);
+	if (of_property_read_u32(np, "qcom,opp-fuse-level", &fuse_corner))
+		pr_err("%s: missing 'qcom,opp-fuse-level' property\n",
+		       __func__);
+
+	of_node_put(np);
+
+	return fuse_corner;
+}
+
+unsigned long cpr_get_opp_hz_for_req(struct dev_pm_opp *ref,
+				     struct device *cpu_dev)
+{
+	u64 rate = 0;
+	struct device_node *ref_np;
+	struct device_node *desc_np;
+	struct device_node *child_np = NULL;
+	struct device_node *child_req_np = NULL;
+
+	desc_np = dev_pm_opp_of_get_opp_desc_node(cpu_dev);
+	if (!desc_np)
+		return 0;
+
+	ref_np = dev_pm_opp_get_of_node(ref);
+	if (!ref_np)
+		goto out_ref;
+
+	do {
+		of_node_put(child_req_np);
+		child_np = of_get_next_available_child(desc_np, child_np);
+		child_req_np = of_parse_phandle(child_np, "required-opps", 0);
+	} while (child_np && child_req_np != ref_np);
+
+	if (child_np && child_req_np == ref_np)
+		of_property_read_u64(child_np, "opp-hz", &rate);
+
+	of_node_put(child_req_np);
+	of_node_put(child_np);
+	of_node_put(ref_np);
+out_ref:
+	of_node_put(desc_np);
+
+	return (unsigned long) rate;
+}
+
+static int cpr_corner_init(struct cpr_drv *drv)
+{
+	const struct cpr_desc *desc = drv->desc;
+	const struct cpr_fuse *fuses = drv->cpr_fuses;
+	int i, level, scaling = 0;
+	unsigned int fnum, fc;
+	const char *quot_offset;
+	struct fuse_corner *fuse, *prev_fuse;
+	struct corner *corner, *end;
+	struct corner_data *cdata;
+	const struct fuse_corner_data *fdata;
+	bool apply_scaling;
+	unsigned long freq_diff, freq_diff_mhz;
+	unsigned long freq;
+	int step_volt = regulator_get_linear_step(drv->vdd_apc);
+	struct dev_pm_opp *opp;
+
+	if (!step_volt)
+		return -EINVAL;
+
+	corner = drv->corners;
+	end = &corner[drv->num_corners - 1];
+
+	cdata = devm_kcalloc(drv->dev, drv->num_corners,
+			     sizeof(struct corner_data),
+			     GFP_KERNEL);
+	if (!cdata)
+		return -ENOMEM;
+
+	/*
+	 * Store maximum frequency for each fuse corner based on the frequency
+	 * plan
+	 */
+	for (level = 1; level <= drv->num_corners; level++) {
+		opp = dev_pm_opp_find_level_exact(&drv->pd.dev, level);
+		if (IS_ERR(opp))
+			return -EINVAL;
+		fc = cpr_get_fuse_corner(opp);
+		if (!fc) {
+			dev_pm_opp_put(opp);
+			return -EINVAL;
+		}
+		fnum = fc - 1;
+		freq = cpr_get_opp_hz_for_req(opp, drv->attached_cpu_dev);
+		if (!freq) {
+			dev_pm_opp_put(opp);
+			return -EINVAL;
+		}
+		cdata[level - 1].fuse_corner = fnum;
+		cdata[level - 1].freq = freq;
+
+		fuse = &drv->fuse_corners[fnum];
+		dev_dbg(drv->dev, "freq: %lu level: %u fuse level: %u\n",
+			freq, dev_pm_opp_get_level(opp) - 1, fnum);
+		if (freq > fuse->max_freq)
+			fuse->max_freq = freq;
+		dev_pm_opp_put(opp);
+	}
+
+	/*
+	 * Get the quotient adjustment scaling factor, according to:
+	 *
+	 * scaling = min(1000 * (QUOT(corner_N) - QUOT(corner_N-1))
+	 *		/ (freq(corner_N) - freq(corner_N-1)), max_factor)
+	 *
+	 * QUOT(corner_N):	quotient read from fuse for fuse corner N
+	 * QUOT(corner_N-1):	quotient read from fuse for fuse corner (N - 1)
+	 * freq(corner_N):	max frequency in MHz supported by fuse corner N
+	 * freq(corner_N-1):	max frequency in MHz supported by fuse corner
+	 *			 (N - 1)
+	 *
+	 * Then walk through the corners mapped to each fuse corner
+	 * and calculate the quotient adjustment for each one using the
+	 * following formula:
+	 *
+	 * quot_adjust = (freq_max - freq_corner) * scaling / 1000
+	 *
+	 * freq_max: max frequency in MHz supported by the fuse corner
+	 * freq_corner: frequency in MHz corresponding to the corner
+	 * scaling: calculated from above equation
+	 *
+	 *
+	 *     +                           +
+	 *     |                         v |
+	 *   q |           f c           o |           f c
+	 *   u |         c               l |         c
+	 *   o |       f                 t |       f
+	 *   t |     c                   a |     c
+	 *     | c f                     g | c f
+	 *     |                         e |
+	 *     +---------------            +----------------
+	 *       0 1 2 3 4 5 6               0 1 2 3 4 5 6
+	 *          corner                      corner
+	 *
+	 *    c = corner
+	 *    f = fuse corner
+	 *
+	 */
+	for (apply_scaling = false, i = 0; corner <= end; corner++, i++) {
+		fnum = cdata[i].fuse_corner;
+		fdata = &desc->cpr_fuses.fuse_corner_data[fnum];
+		quot_offset = fuses[fnum].quotient_offset;
+		fuse = &drv->fuse_corners[fnum];
+		if (fnum)
+			prev_fuse = &drv->fuse_corners[fnum - 1];
+		else
+			prev_fuse = NULL;
+
+		corner->fuse_corner = fuse;
+		corner->freq = cdata[i].freq;
+		corner->uV = fuse->uV;
+
+		if (prev_fuse && cdata[i - 1].freq == prev_fuse->max_freq) {
+			scaling = cpr_calculate_scaling(quot_offset, drv,
+							fdata, corner);
+			if (scaling < 0)
+				return scaling;
+
+			apply_scaling = true;
+		} else if (corner->freq == fuse->max_freq) {
+			/* This is a fuse corner; don't scale anything */
+			apply_scaling = false;
+		}
+
+		if (apply_scaling) {
+			freq_diff = fuse->max_freq - corner->freq;
+			freq_diff_mhz = freq_diff / 1000000;
+			corner->quot_adjust = scaling * freq_diff_mhz / 1000;
+
+			corner->uV = cpr_interpolate(corner, step_volt, fdata);
+		}
+
+		corner->max_uV = fuse->max_uV;
+		corner->min_uV = fuse->min_uV;
+		corner->uV = clamp(corner->uV, corner->min_uV, corner->max_uV);
+		corner->last_uV = corner->uV;
+
+		/* Reduce the ceiling voltage if needed */
+		if (desc->reduce_to_corner_uV && corner->uV < corner->max_uV)
+			corner->max_uV = corner->uV;
+		else if (desc->reduce_to_fuse_uV && fuse->uV < corner->max_uV)
+			corner->max_uV = max(corner->min_uV, fuse->uV);
+
+		dev_dbg(drv->dev, "corner %d: [%d %d %d] quot %d\n", i,
+			corner->min_uV, corner->uV, corner->max_uV,
+			fuse->quot - corner->quot_adjust);
+	}
+
+	return 0;
+}
+
+static const struct cpr_fuse *cpr_get_fuses(struct cpr_drv *drv)
+{
+	const struct cpr_desc *desc = drv->desc;
+	struct cpr_fuse *fuses;
+	int i;
+
+	fuses = devm_kcalloc(drv->dev, desc->num_fuse_corners,
+			     sizeof(struct cpr_fuse),
+			     GFP_KERNEL);
+	if (!fuses)
+		return ERR_PTR(-ENOMEM);
+
+	for (i = 0; i < desc->num_fuse_corners; i++) {
+		char tbuf[32];
+
+		snprintf(tbuf, 32, "cpr_ring_osc%d", i + 1);
+		fuses[i].ring_osc = devm_kstrdup(drv->dev, tbuf, GFP_KERNEL);
+		if (!fuses[i].ring_osc)
+			return ERR_PTR(-ENOMEM);
+
+		snprintf(tbuf, 32, "cpr_init_voltage%d", i + 1);
+		fuses[i].init_voltage = devm_kstrdup(drv->dev, tbuf,
+						     GFP_KERNEL);
+		if (!fuses[i].init_voltage)
+			return ERR_PTR(-ENOMEM);
+
+		snprintf(tbuf, 32, "cpr_quotient%d", i + 1);
+		fuses[i].quotient = devm_kstrdup(drv->dev, tbuf, GFP_KERNEL);
+		if (!fuses[i].quotient)
+			return ERR_PTR(-ENOMEM);
+
+		snprintf(tbuf, 32, "cpr_quotient_offset%d", i + 1);
+		fuses[i].quotient_offset = devm_kstrdup(drv->dev, tbuf,
+							GFP_KERNEL);
+		if (!fuses[i].quotient_offset)
+			return ERR_PTR(-ENOMEM);
+	}
+
+	return fuses;
+}
+
+static void cpr_set_loop_allowed(struct cpr_drv *drv)
+{
+	drv->loop_disabled = false;
+}
+
+static int cpr_init_parameters(struct cpr_drv *drv)
+{
+	const struct cpr_desc *desc = drv->desc;
+	struct clk *clk;
+
+	clk = clk_get(drv->dev, "ref");
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+
+	drv->ref_clk_khz = clk_get_rate(clk) / 1000;
+	clk_put(clk);
+
+	if (desc->timer_cons_up > RBIF_TIMER_ADJ_CONS_UP_MASK ||
+	    desc->timer_cons_down > RBIF_TIMER_ADJ_CONS_DOWN_MASK ||
+	    desc->up_threshold > RBCPR_CTL_UP_THRESHOLD_MASK ||
+	    desc->down_threshold > RBCPR_CTL_DN_THRESHOLD_MASK ||
+	    desc->idle_clocks > RBCPR_STEP_QUOT_IDLE_CLK_MASK ||
+	    desc->clamp_timer_interval > RBIF_TIMER_ADJ_CLAMP_INT_MASK)
+		return -EINVAL;
+
+	dev_dbg(drv->dev, "up threshold = %u, down threshold = %u\n",
+		desc->up_threshold, desc->down_threshold);
+
+	return 0;
+}
+
+static int cpr_find_initial_corner(struct cpr_drv *drv)
+{
+	unsigned long rate;
+	const struct corner *end;
+	struct corner *iter;
+	unsigned int i = 0;
+
+	if (!drv->cpu_clk) {
+		dev_err(drv->dev, "cannot get rate from NULL clk\n");
+		return -EINVAL;
+	}
+
+	end = &drv->corners[drv->num_corners - 1];
+	rate = clk_get_rate(drv->cpu_clk);
+
+	/*
+	 * Some bootloaders set a CPU clock frequency that is not defined
+	 * in the OPP table. When running at an unlisted frequency,
+	 * cpufreq_online() will change to the OPP which has the lowest
+	 * frequency, at or above the unlisted frequency.
+	 * Since cpufreq_online() always "rounds up" in the case of an
+	 * unlisted frequency, this function always "rounds down" in case
+	 * of an unlisted frequency. That way, when cpufreq_online()
+	 * triggers the first ever call to cpr_set_performance_state(),
+	 * it will correctly determine the direction as UP.
+	 */
+	for (iter = drv->corners; iter <= end; iter++) {
+		if (iter->freq > rate)
+			break;
+		i++;
+		if (iter->freq == rate) {
+			drv->corner = iter;
+			break;
+		}
+		if (iter->freq < rate)
+			drv->corner = iter;
+	}
+
+	if (!drv->corner) {
+		dev_err(drv->dev, "boot up corner not found\n");
+		return -EINVAL;
+	}
+
+	dev_dbg(drv->dev, "boot up perf state: %u\n", i);
+
+	return 0;
+}
+
+static const struct cpr_desc qcs404_cpr_desc = {
+	.num_fuse_corners = 3,
+	.min_diff_quot = CPR_FUSE_MIN_QUOT_DIFF,
+	.step_quot = (int []){ 25, 25, 25, },
+	.timer_delay_us = 5000,
+	.timer_cons_up = 0,
+	.timer_cons_down = 2,
+	.up_threshold = 1,
+	.down_threshold = 3,
+	.idle_clocks = 15,
+	.gcnt_us = 1,
+	.vdd_apc_step_up_limit = 1,
+	.vdd_apc_step_down_limit = 1,
+	.cpr_fuses = {
+		.init_voltage_step = 8000,
+		.init_voltage_width = 6,
+		.fuse_corner_data = (struct fuse_corner_data[]){
+			/* fuse corner 0 */
+			{
+				.ref_uV = 1224000,
+				.max_uV = 1224000,
+				.min_uV = 1048000,
+				.max_volt_scale = 0,
+				.max_quot_scale = 0,
+				.quot_offset = 0,
+				.quot_scale = 1,
+				.quot_adjust = 0,
+				.quot_offset_scale = 5,
+				.quot_offset_adjust = 0,
+			},
+			/* fuse corner 1 */
+			{
+				.ref_uV = 1288000,
+				.max_uV = 1288000,
+				.min_uV = 1048000,
+				.max_volt_scale = 2000,
+				.max_quot_scale = 1400,
+				.quot_offset = 0,
+				.quot_scale = 1,
+				.quot_adjust = -20,
+				.quot_offset_scale = 5,
+				.quot_offset_adjust = 0,
+			},
+			/* fuse corner 2 */
+			{
+				.ref_uV = 1352000,
+				.max_uV = 1384000,
+				.min_uV = 1088000,
+				.max_volt_scale = 2000,
+				.max_quot_scale = 1400,
+				.quot_offset = 0,
+				.quot_scale = 1,
+				.quot_adjust = 0,
+				.quot_offset_scale = 5,
+				.quot_offset_adjust = 0,
+			},
+		},
+	},
+};
+
+static const struct acc_desc qcs404_acc_desc = {
+	.settings = (struct reg_sequence[]){
+		{ 0xb120, 0x1041040 },
+		{ 0xb124, 0x41 },
+		{ 0xb120, 0x0 },
+		{ 0xb124, 0x0 },
+		{ 0xb120, 0x0 },
+		{ 0xb124, 0x0 },
+	},
+	.config = (struct reg_sequence[]){
+		{ 0xb138, 0xff },
+		{ 0xb130, 0x5555 },
+	},
+	.num_regs_per_fuse = 2,
+};
+
+static const struct cpr_acc_desc qcs404_cpr_acc_desc = {
+	.cpr_desc = &qcs404_cpr_desc,
+	.acc_desc = &qcs404_acc_desc,
+};
+
+static unsigned int cpr_get_performance_state(struct generic_pm_domain *genpd,
+					      struct dev_pm_opp *opp)
+{
+	return dev_pm_opp_get_level(opp);
+}
+
+static int cpr_power_off(struct generic_pm_domain *domain)
+{
+	struct cpr_drv *drv = container_of(domain, struct cpr_drv, pd);
+
+	return cpr_disable(drv);
+}
+
+static int cpr_power_on(struct generic_pm_domain *domain)
+{
+	struct cpr_drv *drv = container_of(domain, struct cpr_drv, pd);
+
+	return cpr_enable(drv);
+}
+
+static int cpr_pd_attach_dev(struct generic_pm_domain *domain,
+			     struct device *dev)
+{
+	struct cpr_drv *drv = container_of(domain, struct cpr_drv, pd);
+	const struct acc_desc *acc_desc = drv->acc_desc;
+	int ret = 0;
+
+	mutex_lock(&drv->lock);
+
+	dev_dbg(drv->dev, "attach callback for: %s\n", dev_name(dev));
+
+	/*
+	 * This driver only supports scaling voltage for a CPU cluster
+	 * where all CPUs in the cluster share a single regulator.
+	 * Therefore, save the struct device pointer only for the first
+	 * CPU device that gets attached. There is no need to do any
+	 * additional initialization when further CPUs get attached.
+	 */
+	if (drv->attached_cpu_dev)
+		goto unlock;
+
+	/*
+	 * cpr_scale_voltage() requires the direction (if we are changing
+	 * to a higher or lower OPP). The first time
+	 * cpr_set_performance_state() is called, there is no previous
+	 * performance state defined. Therefore, we call
+	 * cpr_find_initial_corner() that gets the CPU clock frequency
+	 * set by the bootloader, so that we can determine the direction
+	 * the first time cpr_set_performance_state() is called.
+	 */
+	drv->cpu_clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(drv->cpu_clk)) {
+		ret = PTR_ERR(drv->cpu_clk);
+		if (ret != -EPROBE_DEFER)
+			dev_err(drv->dev, "could not get cpu clk: %d\n", ret);
+		goto unlock;
+	}
+	drv->attached_cpu_dev = dev;
+
+	dev_dbg(drv->dev, "using cpu clk from: %s\n",
+		dev_name(drv->attached_cpu_dev));
+
+	/*
+	 * Everything related to (virtual) corners has to be initialized
+	 * here, when attaching to the power domain, since we need to know
+	 * the maximum frequency for each fuse corner, and this is only
+	 * available after the cpufreq driver has attached to us.
+	 * The reason for this is that we need to know the highest
+	 * frequency associated with each fuse corner.
+	 */
+	drv->num_corners = dev_pm_opp_get_opp_count(&drv->pd.dev);
+	if (drv->num_corners < 0) {
+		ret = drv->num_corners;
+		goto unlock;
+	}
+	if (drv->num_corners < 2) {
+		dev_err(drv->dev, "need at least 2 OPPs to use CPR\n");
+		ret = -EINVAL;
+		goto unlock;
+	}
+
+	dev_dbg(drv->dev, "number of OPPs: %d\n", drv->num_corners);
+
+	drv->corners = devm_kcalloc(drv->dev, drv->num_corners,
+				    sizeof(*drv->corners),
+				    GFP_KERNEL);
+	if (!drv->corners) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+
+	ret = cpr_corner_init(drv);
+	if (ret)
+		goto unlock;
+
+	cpr_set_loop_allowed(drv);
+
+	ret = cpr_init_parameters(drv);
+	if (ret)
+		goto unlock;
+
+	/* Configure CPR HW but keep it disabled */
+	ret = cpr_config(drv);
+	if (ret)
+		goto unlock;
+
+	ret = cpr_find_initial_corner(drv);
+	if (ret)
+		goto unlock;
+
+	if (acc_desc->config)
+		regmap_multi_reg_write(drv->tcsr, acc_desc->config,
+				       acc_desc->num_regs_per_fuse);
+
+	/* Enable ACC if required */
+	if (acc_desc->enable_mask)
+		regmap_update_bits(drv->tcsr, acc_desc->enable_reg,
+				   acc_desc->enable_mask,
+				   acc_desc->enable_mask);
+
+unlock:
+	mutex_unlock(&drv->lock);
+
+	return ret;
+}
+
+static int cpr_debug_info_show(struct seq_file *s, void *unused)
+{
+	u32 gcnt, ro_sel, ctl, irq_status, reg, error_steps;
+	u32 step_dn, step_up, error, error_lt0, busy;
+	struct cpr_drv *drv = s->private;
+	struct fuse_corner *fuse_corner;
+	struct corner *corner;
+
+	corner = drv->corner;
+	fuse_corner = corner->fuse_corner;
+
+	seq_printf(s, "corner, current_volt = %d uV\n",
+		       corner->last_uV);
+
+	ro_sel = fuse_corner->ring_osc_idx;
+	gcnt = cpr_read(drv, REG_RBCPR_GCNT_TARGET(ro_sel));
+	seq_printf(s, "rbcpr_gcnt_target (%u) = %#02X\n", ro_sel, gcnt);
+
+	ctl = cpr_read(drv, REG_RBCPR_CTL);
+	seq_printf(s, "rbcpr_ctl = %#02X\n", ctl);
+
+	irq_status = cpr_read(drv, REG_RBIF_IRQ_STATUS);
+	seq_printf(s, "rbcpr_irq_status = %#02X\n", irq_status);
+
+	reg = cpr_read(drv, REG_RBCPR_RESULT_0);
+	seq_printf(s, "rbcpr_result_0 = %#02X\n", reg);
+
+	step_dn = reg & 0x01;
+	step_up = (reg >> RBCPR_RESULT0_STEP_UP_SHIFT) & 0x01;
+	seq_printf(s, "  [step_dn = %u", step_dn);
+
+	seq_printf(s, ", step_up = %u", step_up);
+
+	error_steps = (reg >> RBCPR_RESULT0_ERROR_STEPS_SHIFT)
+				& RBCPR_RESULT0_ERROR_STEPS_MASK;
+	seq_printf(s, ", error_steps = %u", error_steps);
+
+	error = (reg >> RBCPR_RESULT0_ERROR_SHIFT) & RBCPR_RESULT0_ERROR_MASK;
+	seq_printf(s, ", error = %u", error);
+
+	error_lt0 = (reg >> RBCPR_RESULT0_ERROR_LT0_SHIFT) & 0x01;
+	seq_printf(s, ", error_lt_0 = %u", error_lt0);
+
+	busy = (reg >> RBCPR_RESULT0_BUSY_SHIFT) & 0x01;
+	seq_printf(s, ", busy = %u]\n", busy);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(cpr_debug_info);
+
+static void cpr_debugfs_init(struct cpr_drv *drv)
+{
+	drv->debugfs = debugfs_create_dir("qcom_cpr", NULL);
+
+	debugfs_create_file("debug_info", 0444, drv->debugfs,
+			    drv, &cpr_debug_info_fops);
+}
+
+static int cpr_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct device *dev = &pdev->dev;
+	struct cpr_drv *drv;
+	int irq, ret;
+	const struct cpr_acc_desc *data;
+	struct device_node *np;
+	u32 cpr_rev = FUSE_REVISION_UNKNOWN;
+
+	data = of_device_get_match_data(dev);
+	if (!data || !data->cpr_desc || !data->acc_desc)
+		return -EINVAL;
+
+	drv = devm_kzalloc(dev, sizeof(*drv), GFP_KERNEL);
+	if (!drv)
+		return -ENOMEM;
+	drv->dev = dev;
+	drv->desc = data->cpr_desc;
+	drv->acc_desc = data->acc_desc;
+
+	drv->fuse_corners = devm_kcalloc(dev, drv->desc->num_fuse_corners,
+					 sizeof(*drv->fuse_corners),
+					 GFP_KERNEL);
+	if (!drv->fuse_corners)
+		return -ENOMEM;
+
+	np = of_parse_phandle(dev->of_node, "acc-syscon", 0);
+	if (!np)
+		return -ENODEV;
+
+	drv->tcsr = syscon_node_to_regmap(np);
+	of_node_put(np);
+	if (IS_ERR(drv->tcsr))
+		return PTR_ERR(drv->tcsr);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	drv->base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(drv->base))
+		return PTR_ERR(drv->base);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return -EINVAL;
+
+	drv->vdd_apc = devm_regulator_get(dev, "vdd-apc");
+	if (IS_ERR(drv->vdd_apc))
+		return PTR_ERR(drv->vdd_apc);
+
+	/*
+	 * Initialize fuse corners, since it simply depends
+	 * on data in efuses.
+	 * Everything related to (virtual) corners has to be
+	 * initialized after attaching to the power domain,
+	 * since it depends on the CPU's OPP table.
+	 */
+	ret = cpr_read_efuse(dev, "cpr_fuse_revision", &cpr_rev);
+	if (ret)
+		return ret;
+
+	drv->cpr_fuses = cpr_get_fuses(drv);
+	if (IS_ERR(drv->cpr_fuses))
+		return PTR_ERR(drv->cpr_fuses);
+
+	ret = cpr_populate_ring_osc_idx(drv);
+	if (ret)
+		return ret;
+
+	ret = cpr_fuse_corner_init(drv);
+	if (ret)
+		return ret;
+
+	mutex_init(&drv->lock);
+
+	ret = devm_request_threaded_irq(dev, irq, NULL,
+					cpr_irq_handler,
+					IRQF_ONESHOT | IRQF_TRIGGER_RISING,
+					"cpr", drv);
+	if (ret)
+		return ret;
+
+	drv->pd.name = devm_kstrdup_const(dev, dev->of_node->full_name,
+					  GFP_KERNEL);
+	if (!drv->pd.name)
+		return -EINVAL;
+
+	drv->pd.power_off = cpr_power_off;
+	drv->pd.power_on = cpr_power_on;
+	drv->pd.set_performance_state = cpr_set_performance_state;
+	drv->pd.opp_to_performance_state = cpr_get_performance_state;
+	drv->pd.attach_dev = cpr_pd_attach_dev;
+
+	ret = pm_genpd_init(&drv->pd, NULL, true);
+	if (ret)
+		return ret;
+
+	ret = of_genpd_add_provider_simple(dev->of_node, &drv->pd);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, drv);
+	cpr_debugfs_init(drv);
+
+	return 0;
+}
+
+static int cpr_remove(struct platform_device *pdev)
+{
+	struct cpr_drv *drv = platform_get_drvdata(pdev);
+
+	if (cpr_is_allowed(drv)) {
+		cpr_ctl_disable(drv);
+		cpr_irq_set(drv, 0);
+	}
+
+	of_genpd_del_provider(pdev->dev.of_node);
+	pm_genpd_remove(&drv->pd);
+
+	debugfs_remove_recursive(drv->debugfs);
+
+	return 0;
+}
+
+static const struct of_device_id cpr_match_table[] = {
+	{ .compatible = "qcom,qcs404-cpr", .data = &qcs404_cpr_acc_desc },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, cpr_match_table);
+
+static struct platform_driver cpr_driver = {
+	.probe		= cpr_probe,
+	.remove		= cpr_remove,
+	.driver		= {
+		.name	= "qcom-cpr",
+		.of_match_table = cpr_match_table,
+	},
+};
+module_platform_driver(cpr_driver);
+
+MODULE_DESCRIPTION("Core Power Reduction (CPR) driver");
+MODULE_LICENSE("GPL v2");