From 6c98adf98236b8644b8f5e1aa7af9f1a88ea2766 Mon Sep 17 00:00:00 2001
From: Robert Marko <robimarko@gmail.com>
Date: Mon, 11 Apr 2022 14:38:08 +0200
Subject: [PATCH] power: Add Qualcomm APM

Add Qualcomm APM driver, which allows scaling cache and memory fabrics.

Signed-off-by: Robert Marko <robimarko@gmail.com>
---
 drivers/power/Kconfig          |   1 +
 drivers/power/Makefile         |   1 +
 drivers/power/qcom/Kconfig     |   7 +
 drivers/power/qcom/Makefile    |   1 +
 drivers/power/qcom/apm.c       | 944 +++++++++++++++++++++++++++++++++
 include/linux/power/qcom/apm.h |  48 ++
 6 files changed, 1002 insertions(+)
 create mode 100644 drivers/power/qcom/Kconfig
 create mode 100644 drivers/power/qcom/Makefile
 create mode 100644 drivers/power/qcom/apm.c
 create mode 100644 include/linux/power/qcom/apm.h

--- a/drivers/power/Kconfig
+++ b/drivers/power/Kconfig
@@ -2,3 +2,4 @@
 source "drivers/power/reset/Kconfig"
 source "drivers/power/sequencing/Kconfig"
 source "drivers/power/supply/Kconfig"
+source "drivers/power/qcom/Kconfig"
--- a/drivers/power/Makefile
+++ b/drivers/power/Makefile
@@ -2,3 +2,4 @@
 obj-$(CONFIG_POWER_RESET)	+= reset/
 obj-$(CONFIG_POWER_SEQUENCING)	+= sequencing/
 obj-$(CONFIG_POWER_SUPPLY)	+= supply/
+obj-$(CONFIG_QCOM_APM)		+= qcom/
--- /dev/null
+++ b/drivers/power/qcom/Kconfig
@@ -0,0 +1,7 @@
+config QCOM_APM
+       bool "Qualcomm Technologies Inc platform specific APM driver"
+       help
+	Platform specific driver to manage the power source of
+	memory arrays. Interfaces with regulator drivers to ensure
+	SRAM Vmin requirements are met across different performance
+	levels.
--- /dev/null
+++ b/drivers/power/qcom/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_QCOM_APM)		+= apm.o
--- /dev/null
+++ b/drivers/power/qcom/apm.c
@@ -0,0 +1,941 @@
+/*
+ * Copyright (c) 2015-2016, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#define pr_fmt(fmt) "%s: " fmt, __func__
+
+#include <linux/debugfs.h>
+#include <linux/delay.h>
+#include <linux/of_device.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/power/qcom/apm.h>
+
+/*
+ *        VDD_APCC
+ * =============================================================
+ *       |      VDD_MX                  |                    |
+ *       |    ==========================|=============       |
+ *    ___|___   ___|___    ___|___   ___|___    ___|___   ___|___
+ *   |       | |       |  |       | |       |  |       | |       |
+ *   | APCC  | | MX HS |  | MX HS | | APCC  |  | MX HS | | APCC  |
+ *   |  HS   | |       |  |       | |  HS   |  |       | |  HS   |
+ *   |_______| |_______|  |_______| |_______|  |_______| |_______|
+ *       |_________|          |_________|         |__________|
+ *            |                    |                    |
+ *      ______|_____         ______|_____        _______|_____
+ *     |            |       |            |      |             |
+ *     |            |       |            |      |             |
+ *     |  CPU MEM   |       |   L2 MEM   |      |    L3 MEM   |
+ *     |   Arrays   |       |   Arrays   |      |    Arrays   |
+ *     |            |       |            |      |             |
+ *     |____________|       |____________|      |_____________|
+ *
+ */
+
+/* Register value definitions */
+#define APCS_GFMUXA_SEL_VAL            0x13
+#define APCS_GFMUXA_DESEL_VAL          0x03
+#define MSM_APM_MX_MODE_VAL            0x00
+#define MSM_APM_APCC_MODE_VAL          0x10
+#define MSM_APM_MX_DONE_VAL            0x00
+#define MSM_APM_APCC_DONE_VAL          0x03
+#define MSM_APM_OVERRIDE_SEL_VAL       0xb0
+#define MSM_APM_SEC_CLK_SEL_VAL        0x30
+#define SPM_EVENT_SET_VAL              0x01
+#define SPM_EVENT_CLEAR_VAL            0x00
+
+/* Register bit mask definitions */
+#define MSM_APM_CTL_STS_MASK            0x0f
+
+/* Register offset definitions */
+#define APCC_APM_MODE              0x00000098
+#define APCC_APM_CTL_STS           0x000000a8
+#define APCS_SPARE                 0x00000068
+#define APCS_VERSION               0x00000fd0
+
+#define HMSS_VERSION_1P2           0x10020000
+
+#define MSM_APM_SWITCH_TIMEOUT_US  10
+#define SPM_WAKEUP_DELAY_US        2
+#define SPM_EVENT_NUM              6
+
+#define MSM_APM_DRIVER_NAME        "qcom,msm-apm"
+
+enum {
+	MSM8996_ID,
+	MSM8953_ID,
+	IPQ807x_ID,
+};
+
+struct msm_apm_ctrl_dev {
+	struct list_head	list;
+	struct device		*dev;
+	enum msm_apm_supply	supply;
+	spinlock_t		lock;
+	void __iomem		*reg_base;
+	void __iomem		*apcs_csr_base;
+	void __iomem		**apcs_spm_events_addr;
+	void __iomem		*apc0_pll_ctl_addr;
+	void __iomem		*apc1_pll_ctl_addr;
+	u32			version;
+	struct dentry		*debugfs;
+	u32			msm_id;
+};
+
+#if defined(CONFIG_DEBUG_FS)
+static struct dentry *apm_debugfs_base;
+#endif
+
+static DEFINE_MUTEX(apm_ctrl_list_mutex);
+static LIST_HEAD(apm_ctrl_list);
+
+/*
+ * Get the resources associated with the APM controller from device tree
+ * and remap all I/O addresses that are relevant to this HW revision.
+ */
+static int msm_apm_ctrl_devm_ioremap(struct platform_device *pdev,
+				     struct msm_apm_ctrl_dev *ctrl)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	static const char *res_name[SPM_EVENT_NUM] = {
+		"apc0-l2-spm",
+		"apc1-l2-spm",
+		"apc0-cpu0-spm",
+		"apc0-cpu1-spm",
+		"apc1-cpu0-spm",
+		"apc1-cpu1-spm"
+	};
+	int i, ret = 0;
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "pm-apcc-glb");
+	if (!res) {
+		dev_err(dev, "Missing PM APCC Global register physical address");
+		return -EINVAL;
+	}
+	ctrl->reg_base = devm_ioremap(dev, res->start, resource_size(res));
+	if (!ctrl->reg_base) {
+		dev_err(dev, "Failed to map PM APCC Global registers\n");
+		return -ENOMEM;
+	}
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "apcs-csr");
+	if (!res) {
+		dev_err(dev, "Missing APCS CSR physical base address");
+		return -EINVAL;
+	}
+	ctrl->apcs_csr_base = devm_ioremap(dev, res->start, resource_size(res));
+	if (!ctrl->apcs_csr_base) {
+		dev_err(dev, "Failed to map APCS CSR registers\n");
+		return -ENOMEM;
+	}
+
+	ctrl->version = readl_relaxed(ctrl->apcs_csr_base + APCS_VERSION);
+
+	if (ctrl->version >= HMSS_VERSION_1P2)
+		return ret;
+
+	ctrl->apcs_spm_events_addr = devm_kzalloc(&pdev->dev,
+						  SPM_EVENT_NUM
+						  * sizeof(void __iomem *),
+						  GFP_KERNEL);
+	if (!ctrl->apcs_spm_events_addr) {
+		dev_err(dev, "Failed to allocate memory for APCS SPM event registers\n");
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < SPM_EVENT_NUM; i++) {
+		res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
+						   res_name[i]);
+		if (!res) {
+			dev_err(dev, "Missing address for %s\n", res_name[i]);
+			ret = -EINVAL;
+			goto free_events;
+		}
+
+		ctrl->apcs_spm_events_addr[i] = devm_ioremap(dev, res->start,
+						resource_size(res));
+		if (!ctrl->apcs_spm_events_addr[i]) {
+			dev_err(dev, "Failed to map %s\n", res_name[i]);
+			ret = -ENOMEM;
+			goto free_events;
+		}
+
+		dev_dbg(dev, "%s event phys: %pa virt:0x%p\n", res_name[i],
+			&res->start, ctrl->apcs_spm_events_addr[i]);
+	}
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
+					   "apc0-pll-ctl");
+	if (!res) {
+		dev_err(dev, "Missing APC0 PLL CTL physical address\n");
+		ret = -EINVAL;
+		goto free_events;
+	}
+
+	ctrl->apc0_pll_ctl_addr = devm_ioremap(dev,
+					   res->start,
+					   resource_size(res));
+	if (!ctrl->apc0_pll_ctl_addr) {
+		dev_err(dev, "Failed to map APC0 PLL CTL register\n");
+		ret = -ENOMEM;
+		goto free_events;
+	}
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
+					   "apc1-pll-ctl");
+	if (!res) {
+		dev_err(dev, "Missing APC1 PLL CTL physical address\n");
+		ret = -EINVAL;
+		goto free_events;
+	}
+
+	ctrl->apc1_pll_ctl_addr = devm_ioremap(dev,
+					   res->start,
+					   resource_size(res));
+	if (!ctrl->apc1_pll_ctl_addr) {
+		dev_err(dev, "Failed to map APC1 PLL CTL register\n");
+		ret = -ENOMEM;
+		goto free_events;
+	}
+
+	return ret;
+
+free_events:
+	devm_kfree(dev, ctrl->apcs_spm_events_addr);
+	return ret;
+}
+
+/* 8953 register offset definition */
+#define MSM8953_APM_DLY_CNTR	0x2ac
+
+/* Register field shift definitions */
+#define APM_CTL_SEL_SWITCH_DLY_SHIFT	0
+#define APM_CTL_RESUME_CLK_DLY_SHIFT	8
+#define APM_CTL_HALT_CLK_DLY_SHIFT	16
+#define APM_CTL_POST_HALT_DLY_SHIFT	24
+
+/* Register field mask definitions */
+#define APM_CTL_SEL_SWITCH_DLY_MASK	GENMASK(7, 0)
+#define APM_CTL_RESUME_CLK_DLY_MASK	GENMASK(15, 8)
+#define APM_CTL_HALT_CLK_DLY_MASK	GENMASK(23, 16)
+#define APM_CTL_POST_HALT_DLY_MASK	GENMASK(31, 24)
+
+/*
+ * Get the resources associated with the msm8953 APM controller from
+ * device tree, remap all I/O addresses, and program the initial
+ * register configuration required for the 8953 APM controller device.
+ */
+static int msm8953_apm_ctrl_init(struct platform_device *pdev,
+				     struct msm_apm_ctrl_dev *ctrl)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	u32 delay_counter, val = 0, regval = 0;
+	int rc = 0;
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "pm-apcc-glb");
+	if (!res) {
+		dev_err(dev, "Missing PM APCC Global register physical address\n");
+		return -ENODEV;
+	}
+	ctrl->reg_base = devm_ioremap(dev, res->start, resource_size(res));
+	if (!ctrl->reg_base) {
+		dev_err(dev, "Failed to map PM APCC Global registers\n");
+		return -ENOMEM;
+	}
+
+	/*
+	 * Initial APM register configuration required before starting
+	 * APM HW controller.
+	 */
+	regval = readl_relaxed(ctrl->reg_base + MSM8953_APM_DLY_CNTR);
+	val = regval;
+
+	if (of_property_present(dev->of_node, "qcom,apm-post-halt-delay")) {
+		rc = of_property_read_u32(dev->of_node,
+				"qcom,apm-post-halt-delay", &delay_counter);
+		if (rc < 0) {
+			dev_err(dev, "apm-post-halt-delay read failed, rc = %d",
+				rc);
+			return rc;
+		}
+
+		val &= ~APM_CTL_POST_HALT_DLY_MASK;
+		val |= (delay_counter << APM_CTL_POST_HALT_DLY_SHIFT)
+			& APM_CTL_POST_HALT_DLY_MASK;
+	}
+
+	if (of_property_present(dev->of_node, "qcom,apm-halt-clk-delay")) {
+		rc = of_property_read_u32(dev->of_node,
+				"qcom,apm-halt-clk-delay", &delay_counter);
+		if (rc < 0) {
+			dev_err(dev, "apm-halt-clk-delay read failed, rc = %d",
+				rc);
+			return rc;
+		}
+
+		val &= ~APM_CTL_HALT_CLK_DLY_MASK;
+		val |= (delay_counter << APM_CTL_HALT_CLK_DLY_SHIFT)
+			& APM_CTL_HALT_CLK_DLY_MASK;
+	}
+
+	if (of_property_present(dev->of_node, "qcom,apm-resume-clk-delay")) {
+		rc = of_property_read_u32(dev->of_node,
+				"qcom,apm-resume-clk-delay", &delay_counter);
+		if (rc < 0) {
+			dev_err(dev, "apm-resume-clk-delay read failed, rc = %d",
+				rc);
+			return rc;
+		}
+
+		val &= ~APM_CTL_RESUME_CLK_DLY_MASK;
+		val |= (delay_counter << APM_CTL_RESUME_CLK_DLY_SHIFT)
+			& APM_CTL_RESUME_CLK_DLY_MASK;
+	}
+
+	if (of_property_present(dev->of_node, "qcom,apm-sel-switch-delay")) {
+		rc = of_property_read_u32(dev->of_node,
+				"qcom,apm-sel-switch-delay", &delay_counter);
+		if (rc < 0) {
+			dev_err(dev, "apm-sel-switch-delay read failed, rc = %d",
+				rc);
+			return rc;
+		}
+
+		val &= ~APM_CTL_SEL_SWITCH_DLY_MASK;
+		val |= (delay_counter << APM_CTL_SEL_SWITCH_DLY_SHIFT)
+			& APM_CTL_SEL_SWITCH_DLY_MASK;
+	}
+
+	if (val != regval) {
+		writel_relaxed(val, ctrl->reg_base + MSM8953_APM_DLY_CNTR);
+		/* make sure write completes before return */
+		mb();
+	}
+
+	return rc;
+}
+
+static int msm8996_apm_switch_to_mx(struct msm_apm_ctrl_dev *ctrl_dev)
+{
+	int i, timeout = MSM_APM_SWITCH_TIMEOUT_US;
+	u32 regval;
+	int ret = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ctrl_dev->lock, flags);
+
+	/* Perform revision-specific programming steps */
+	if (ctrl_dev->version < HMSS_VERSION_1P2) {
+		/* Clear SPM events */
+		for (i = 0; i < SPM_EVENT_NUM; i++)
+			writel_relaxed(SPM_EVENT_CLEAR_VAL,
+				       ctrl_dev->apcs_spm_events_addr[i]);
+
+		udelay(SPM_WAKEUP_DELAY_US);
+
+		/* Switch APC/CBF to GPLL0 clock */
+		writel_relaxed(APCS_GFMUXA_SEL_VAL,
+			       ctrl_dev->apcs_csr_base + APCS_SPARE);
+		ndelay(200);
+		writel_relaxed(MSM_APM_OVERRIDE_SEL_VAL,
+			       ctrl_dev->apc0_pll_ctl_addr);
+		ndelay(200);
+		writel_relaxed(MSM_APM_OVERRIDE_SEL_VAL,
+			       ctrl_dev->apc1_pll_ctl_addr);
+
+		/* Ensure writes complete before proceeding */
+		mb();
+	}
+
+	/* Switch arrays to MX supply and wait for its completion */
+	writel_relaxed(MSM_APM_MX_MODE_VAL, ctrl_dev->reg_base +
+		       APCC_APM_MODE);
+
+	/* Ensure write above completes before delaying */
+	mb();
+
+	while (timeout > 0) {
+		regval = readl_relaxed(ctrl_dev->reg_base + APCC_APM_CTL_STS);
+		if ((regval & MSM_APM_CTL_STS_MASK) ==
+		    MSM_APM_MX_DONE_VAL)
+			break;
+
+		udelay(1);
+		timeout--;
+	}
+
+	if (timeout == 0) {
+		ret = -ETIMEDOUT;
+		dev_err(ctrl_dev->dev, "APCC to MX APM switch timed out. APCC_APM_CTL_STS=0x%x\n",
+			regval);
+	}
+
+	/* Perform revision-specific programming steps */
+	if (ctrl_dev->version < HMSS_VERSION_1P2) {
+		/* Switch APC/CBF clocks to original source */
+		writel_relaxed(APCS_GFMUXA_DESEL_VAL,
+			       ctrl_dev->apcs_csr_base + APCS_SPARE);
+		ndelay(200);
+		writel_relaxed(MSM_APM_SEC_CLK_SEL_VAL,
+			       ctrl_dev->apc0_pll_ctl_addr);
+		ndelay(200);
+		writel_relaxed(MSM_APM_SEC_CLK_SEL_VAL,
+			       ctrl_dev->apc1_pll_ctl_addr);
+
+		/* Complete clock source switch before SPM event sequence */
+		mb();
+
+		/* Set SPM events */
+		for (i = 0; i < SPM_EVENT_NUM; i++)
+			writel_relaxed(SPM_EVENT_SET_VAL,
+				       ctrl_dev->apcs_spm_events_addr[i]);
+	}
+
+	if (!ret) {
+		ctrl_dev->supply = MSM_APM_SUPPLY_MX;
+		dev_dbg(ctrl_dev->dev, "APM supply switched to MX\n");
+	}
+
+	spin_unlock_irqrestore(&ctrl_dev->lock, flags);
+
+	return ret;
+}
+
+static int msm8996_apm_switch_to_apcc(struct msm_apm_ctrl_dev *ctrl_dev)
+{
+	int i, timeout = MSM_APM_SWITCH_TIMEOUT_US;
+	u32 regval;
+	int ret = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ctrl_dev->lock, flags);
+
+	/* Perform revision-specific programming steps */
+	if (ctrl_dev->version < HMSS_VERSION_1P2) {
+		/* Clear SPM events */
+		for (i = 0; i < SPM_EVENT_NUM; i++)
+			writel_relaxed(SPM_EVENT_CLEAR_VAL,
+				       ctrl_dev->apcs_spm_events_addr[i]);
+
+		udelay(SPM_WAKEUP_DELAY_US);
+
+		/* Switch APC/CBF to GPLL0 clock */
+		writel_relaxed(APCS_GFMUXA_SEL_VAL,
+			       ctrl_dev->apcs_csr_base + APCS_SPARE);
+		ndelay(200);
+		writel_relaxed(MSM_APM_OVERRIDE_SEL_VAL,
+			       ctrl_dev->apc0_pll_ctl_addr);
+		ndelay(200);
+		writel_relaxed(MSM_APM_OVERRIDE_SEL_VAL,
+			       ctrl_dev->apc1_pll_ctl_addr);
+
+		/* Ensure previous writes complete before proceeding */
+		mb();
+	}
+
+	/* Switch arrays to APCC supply and wait for its completion */
+	writel_relaxed(MSM_APM_APCC_MODE_VAL, ctrl_dev->reg_base +
+		       APCC_APM_MODE);
+
+	/* Ensure write above completes before delaying */
+	mb();
+
+	while (timeout > 0) {
+		regval = readl_relaxed(ctrl_dev->reg_base + APCC_APM_CTL_STS);
+		if ((regval & MSM_APM_CTL_STS_MASK) ==
+		    MSM_APM_APCC_DONE_VAL)
+			break;
+
+		udelay(1);
+		timeout--;
+	}
+
+	if (timeout == 0) {
+		ret = -ETIMEDOUT;
+		dev_err(ctrl_dev->dev, "MX to APCC APM switch timed out. APCC_APM_CTL_STS=0x%x\n",
+			regval);
+	}
+
+	/* Perform revision-specific programming steps */
+	if (ctrl_dev->version < HMSS_VERSION_1P2) {
+		/* Set SPM events */
+		for (i = 0; i < SPM_EVENT_NUM; i++)
+			writel_relaxed(SPM_EVENT_SET_VAL,
+				       ctrl_dev->apcs_spm_events_addr[i]);
+
+		/* Complete SPM event sequence before clock source switch */
+		mb();
+
+		/* Switch APC/CBF clocks to original source */
+		writel_relaxed(APCS_GFMUXA_DESEL_VAL,
+			       ctrl_dev->apcs_csr_base + APCS_SPARE);
+		ndelay(200);
+		writel_relaxed(MSM_APM_SEC_CLK_SEL_VAL,
+			       ctrl_dev->apc0_pll_ctl_addr);
+		ndelay(200);
+		writel_relaxed(MSM_APM_SEC_CLK_SEL_VAL,
+			       ctrl_dev->apc1_pll_ctl_addr);
+	}
+
+	if (!ret) {
+		ctrl_dev->supply = MSM_APM_SUPPLY_APCC;
+		dev_dbg(ctrl_dev->dev, "APM supply switched to APCC\n");
+	}
+
+	spin_unlock_irqrestore(&ctrl_dev->lock, flags);
+
+	return ret;
+}
+
+/* 8953 register value definitions */
+#define MSM8953_APM_MX_MODE_VAL            0x00
+#define MSM8953_APM_APCC_MODE_VAL          0x02
+#define MSM8953_APM_MX_DONE_VAL            0x00
+#define MSM8953_APM_APCC_DONE_VAL          0x03
+
+/* 8953 register offset definitions */
+#define MSM8953_APCC_APM_MODE              0x000002a8
+#define MSM8953_APCC_APM_CTL_STS           0x000002b0
+
+/* 8953 constants */
+#define MSM8953_APM_SWITCH_TIMEOUT_US      500
+
+/* Register bit mask definitions */
+#define MSM8953_APM_CTL_STS_MASK           0x1f
+
+static int msm8953_apm_switch_to_mx(struct msm_apm_ctrl_dev *ctrl_dev)
+{
+	int timeout = MSM8953_APM_SWITCH_TIMEOUT_US;
+	u32 regval;
+	int ret = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ctrl_dev->lock, flags);
+
+	/* Switch arrays to MX supply and wait for its completion */
+	writel_relaxed(MSM8953_APM_MX_MODE_VAL, ctrl_dev->reg_base +
+		       MSM8953_APCC_APM_MODE);
+
+	/* Ensure write above completes before delaying */
+	mb();
+
+	while (timeout > 0) {
+		regval = readl_relaxed(ctrl_dev->reg_base +
+					MSM8953_APCC_APM_CTL_STS);
+		if ((regval & MSM8953_APM_CTL_STS_MASK) ==
+				MSM8953_APM_MX_DONE_VAL)
+			break;
+
+		udelay(1);
+		timeout--;
+	}
+
+	if (timeout == 0) {
+		ret = -ETIMEDOUT;
+		dev_err(ctrl_dev->dev, "APCC to MX APM switch timed out. APCC_APM_CTL_STS=0x%x\n",
+			regval);
+	} else {
+		ctrl_dev->supply = MSM_APM_SUPPLY_MX;
+		dev_dbg(ctrl_dev->dev, "APM supply switched to MX\n");
+	}
+
+	spin_unlock_irqrestore(&ctrl_dev->lock, flags);
+
+	return ret;
+}
+
+static int msm8953_apm_switch_to_apcc(struct msm_apm_ctrl_dev *ctrl_dev)
+{
+	int timeout = MSM8953_APM_SWITCH_TIMEOUT_US;
+	u32 regval;
+	int ret = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ctrl_dev->lock, flags);
+
+	/* Switch arrays to APCC supply and wait for its completion */
+	writel_relaxed(MSM8953_APM_APCC_MODE_VAL, ctrl_dev->reg_base +
+		       MSM8953_APCC_APM_MODE);
+
+	/* Ensure write above completes before delaying */
+	mb();
+
+	while (timeout > 0) {
+		regval = readl_relaxed(ctrl_dev->reg_base +
+					MSM8953_APCC_APM_CTL_STS);
+		if ((regval & MSM8953_APM_CTL_STS_MASK) ==
+				MSM8953_APM_APCC_DONE_VAL)
+			break;
+
+		udelay(1);
+		timeout--;
+	}
+
+	if (timeout == 0) {
+		ret = -ETIMEDOUT;
+		dev_err(ctrl_dev->dev, "MX to APCC APM switch timed out. APCC_APM_CTL_STS=0x%x\n",
+			regval);
+	} else {
+		ctrl_dev->supply = MSM_APM_SUPPLY_APCC;
+		dev_dbg(ctrl_dev->dev, "APM supply switched to APCC\n");
+	}
+
+	spin_unlock_irqrestore(&ctrl_dev->lock, flags);
+
+	return ret;
+}
+
+static int msm_apm_switch_to_mx(struct msm_apm_ctrl_dev *ctrl_dev)
+{
+	int ret = 0;
+
+	switch (ctrl_dev->msm_id) {
+	case MSM8996_ID:
+		ret = msm8996_apm_switch_to_mx(ctrl_dev);
+		break;
+	case MSM8953_ID:
+	case IPQ807x_ID:
+		ret = msm8953_apm_switch_to_mx(ctrl_dev);
+		break;
+	}
+
+	return ret;
+}
+
+static int msm_apm_switch_to_apcc(struct msm_apm_ctrl_dev *ctrl_dev)
+{
+	int ret = 0;
+
+	switch (ctrl_dev->msm_id) {
+	case MSM8996_ID:
+		ret = msm8996_apm_switch_to_apcc(ctrl_dev);
+		break;
+	case MSM8953_ID:
+	case IPQ807x_ID:
+		ret = msm8953_apm_switch_to_apcc(ctrl_dev);
+		break;
+	}
+
+	return ret;
+}
+
+/**
+ * msm_apm_get_supply() - Returns the supply that is currently
+ *			powering the memory arrays
+ * @ctrl_dev:                   Pointer to an MSM APM controller device
+ *
+ * Returns the supply currently selected by the APM.
+ */
+int msm_apm_get_supply(struct msm_apm_ctrl_dev *ctrl_dev)
+{
+	return ctrl_dev->supply;
+}
+EXPORT_SYMBOL(msm_apm_get_supply);
+
+/**
+ * msm_apm_set_supply() - Perform the necessary steps to switch the voltage
+ *                        source of the memory arrays to a given supply
+ * @ctrl_dev:                   Pointer to an MSM APM controller device
+ * @supply:                     Power rail to use as supply for the memory
+ *                              arrays
+ *
+ * Returns 0 on success, -ETIMEDOUT on APM switch timeout, or -EPERM if
+ * the supply is not supported.
+ */
+int msm_apm_set_supply(struct msm_apm_ctrl_dev *ctrl_dev,
+		       enum msm_apm_supply supply)
+{
+	int ret;
+
+	switch (supply) {
+	case MSM_APM_SUPPLY_APCC:
+		ret = msm_apm_switch_to_apcc(ctrl_dev);
+		break;
+	case MSM_APM_SUPPLY_MX:
+		ret = msm_apm_switch_to_mx(ctrl_dev);
+		break;
+	default:
+		ret = -EPERM;
+		break;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(msm_apm_set_supply);
+
+/**
+ * msm_apm_ctrl_dev_get() - get a handle to the MSM APM controller linked to
+ *                          the device in device tree
+ * @dev:                    Pointer to the device
+ *
+ * The device must specify "qcom,apm-ctrl" property in its device tree
+ * node which points to an MSM APM controller device node.
+ *
+ * Returns an MSM APM controller handle if successful or ERR_PTR on any error.
+ * If the APM controller device hasn't probed yet, ERR_PTR(-EPROBE_DEFER) is
+ * returned.
+ */
+struct msm_apm_ctrl_dev *msm_apm_ctrl_dev_get(struct device *dev)
+{
+	struct msm_apm_ctrl_dev *ctrl_dev = NULL;
+	struct msm_apm_ctrl_dev *dev_found = ERR_PTR(-EPROBE_DEFER);
+	struct device_node *ctrl_node;
+
+	if (!dev || !dev->of_node) {
+		pr_err("Invalid device node\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	ctrl_node = of_parse_phandle(dev->of_node, "qcom,apm-ctrl", 0);
+	if (!ctrl_node) {
+		pr_err("Could not find qcom,apm-ctrl property in %s\n",
+		       dev->of_node->full_name);
+		return ERR_PTR(-ENXIO);
+	}
+
+	mutex_lock(&apm_ctrl_list_mutex);
+	list_for_each_entry(ctrl_dev, &apm_ctrl_list, list) {
+		if (ctrl_dev->dev && ctrl_dev->dev->of_node == ctrl_node) {
+			dev_found = ctrl_dev;
+			break;
+		}
+	}
+	mutex_unlock(&apm_ctrl_list_mutex);
+
+	of_node_put(ctrl_node);
+	return dev_found;
+}
+EXPORT_SYMBOL(msm_apm_ctrl_dev_get);
+
+#if defined(CONFIG_DEBUG_FS)
+
+static int apm_supply_dbg_open(struct inode *inode, struct file *filep)
+{
+	filep->private_data = inode->i_private;
+
+	return 0;
+}
+
+static ssize_t apm_supply_dbg_read(struct file *filep, char __user *ubuf,
+				   size_t count, loff_t *ppos)
+{
+	struct msm_apm_ctrl_dev *ctrl_dev = filep->private_data;
+	char buf[10];
+	int len;
+
+	if (!ctrl_dev) {
+		pr_err("invalid apm ctrl handle\n");
+		return -ENODEV;
+	}
+
+	if (ctrl_dev->supply == MSM_APM_SUPPLY_APCC)
+		len = snprintf(buf, sizeof(buf), "APCC\n");
+	else if (ctrl_dev->supply == MSM_APM_SUPPLY_MX)
+		len = snprintf(buf, sizeof(buf), "MX\n");
+	else
+		len = snprintf(buf, sizeof(buf), "ERR\n");
+
+	return simple_read_from_buffer(ubuf, count, ppos, buf, len);
+}
+
+static const struct file_operations apm_supply_fops = {
+	.open = apm_supply_dbg_open,
+	.read = apm_supply_dbg_read,
+};
+
+static void apm_debugfs_base_init(void)
+{
+	apm_debugfs_base = debugfs_create_dir("msm-apm", NULL);
+
+	if (IS_ERR_OR_NULL(apm_debugfs_base))
+		pr_err("msm-apm debugfs base directory creation failed\n");
+}
+
+static void apm_debugfs_init(struct msm_apm_ctrl_dev *ctrl_dev)
+{
+	struct dentry *temp;
+
+	if (IS_ERR_OR_NULL(apm_debugfs_base)) {
+		pr_err("Base directory missing, cannot create apm debugfs nodes\n");
+		return;
+	}
+
+	ctrl_dev->debugfs = debugfs_create_dir(dev_name(ctrl_dev->dev),
+					       apm_debugfs_base);
+	if (IS_ERR_OR_NULL(ctrl_dev->debugfs)) {
+		pr_err("%s debugfs directory creation failed\n",
+		       dev_name(ctrl_dev->dev));
+		return;
+	}
+
+	temp = debugfs_create_file("supply", S_IRUGO, ctrl_dev->debugfs,
+				   ctrl_dev, &apm_supply_fops);
+	if (IS_ERR_OR_NULL(temp)) {
+		pr_err("supply mode creation failed\n");
+		return;
+	}
+}
+
+static void apm_debugfs_deinit(struct msm_apm_ctrl_dev *ctrl_dev)
+{
+	if (!IS_ERR_OR_NULL(ctrl_dev->debugfs))
+		debugfs_remove_recursive(ctrl_dev->debugfs);
+}
+
+static void apm_debugfs_base_remove(void)
+{
+	debugfs_remove_recursive(apm_debugfs_base);
+}
+#else
+
+static void apm_debugfs_base_init(void)
+{}
+
+static void apm_debugfs_init(struct msm_apm_ctrl_dev *ctrl_dev)
+{}
+
+static void apm_debugfs_deinit(struct msm_apm_ctrl_dev *ctrl_dev)
+{}
+
+static void apm_debugfs_base_remove(void)
+{}
+
+#endif
+
+static const struct of_device_id msm_apm_match_table[] = {
+	{
+		.compatible = "qcom,msm-apm",
+		.data = (void *)(uintptr_t)MSM8996_ID,
+	},
+	{
+		.compatible = "qcom,msm8953-apm",
+		.data = (void *)(uintptr_t)MSM8953_ID,
+	},
+	{
+		.compatible = "qcom,ipq807x-apm",
+		.data = (void *)(uintptr_t)IPQ807x_ID,
+	},
+	{}
+};
+
+static int msm_apm_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct msm_apm_ctrl_dev *ctrl;
+	const struct of_device_id *match;
+	int ret = 0;
+
+	dev_dbg(dev, "probing MSM Array Power Mux driver\n");
+
+	if (!dev->of_node) {
+		dev_err(dev, "Device tree node is missing\n");
+		return -ENODEV;
+	}
+
+	match = of_match_device(msm_apm_match_table, dev);
+	if (!match)
+		return -ENODEV;
+
+	ctrl = devm_kzalloc(dev, sizeof(*ctrl), GFP_KERNEL);
+	if (!ctrl) {
+		dev_err(dev, "MSM APM controller memory allocation failed\n");
+		return -ENOMEM;
+	}
+
+	INIT_LIST_HEAD(&ctrl->list);
+	spin_lock_init(&ctrl->lock);
+	ctrl->dev = dev;
+	ctrl->msm_id = (uintptr_t)match->data;
+	platform_set_drvdata(pdev, ctrl);
+
+	switch (ctrl->msm_id) {
+	case MSM8996_ID:
+		ret = msm_apm_ctrl_devm_ioremap(pdev, ctrl);
+		if (ret) {
+			dev_err(dev, "Failed to add APM controller device\n");
+			return ret;
+		}
+		break;
+	case MSM8953_ID:
+	case IPQ807x_ID:
+		ret = msm8953_apm_ctrl_init(pdev, ctrl);
+		if (ret) {
+			dev_err(dev, "Failed to initialize APM controller device: ret=%d\n",
+				ret);
+			return ret;
+		}
+		break;
+	default:
+		dev_err(dev, "unable to add APM controller device for msm_id:%d\n",
+			ctrl->msm_id);
+		return -ENODEV;
+	}
+
+	apm_debugfs_init(ctrl);
+	mutex_lock(&apm_ctrl_list_mutex);
+	list_add_tail(&ctrl->list, &apm_ctrl_list);
+	mutex_unlock(&apm_ctrl_list_mutex);
+
+	dev_dbg(dev, "MSM Array Power Mux driver probe successful");
+
+	return ret;
+}
+
+static void msm_apm_remove(struct platform_device *pdev)
+{
+	struct msm_apm_ctrl_dev *ctrl_dev;
+
+	ctrl_dev = platform_get_drvdata(pdev);
+	if (ctrl_dev) {
+		mutex_lock(&apm_ctrl_list_mutex);
+		list_del(&ctrl_dev->list);
+		mutex_unlock(&apm_ctrl_list_mutex);
+		apm_debugfs_deinit(ctrl_dev);
+	}
+}
+
+static struct platform_driver msm_apm_driver = {
+	.driver		= {
+		.name		= MSM_APM_DRIVER_NAME,
+		.of_match_table	= msm_apm_match_table,
+	},
+	.probe		= msm_apm_probe,
+	.remove		= msm_apm_remove,
+};
+
+static int __init msm_apm_init(void)
+{
+	apm_debugfs_base_init();
+	return platform_driver_register(&msm_apm_driver);
+}
+
+static void __exit msm_apm_exit(void)
+{
+	platform_driver_unregister(&msm_apm_driver);
+	apm_debugfs_base_remove();
+}
+
+arch_initcall(msm_apm_init);
+module_exit(msm_apm_exit);
+
+MODULE_DESCRIPTION("MSM Array Power Mux driver");
+MODULE_LICENSE("GPL v2");
--- /dev/null
+++ b/include/linux/power/qcom/apm.h
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2015, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __LINUX_POWER_QCOM_APM_H__
+#define __LINUX_POWER_QCOM_APM_H__
+
+#include <linux/device.h>
+#include <linux/err.h>
+
+/**
+ * enum msm_apm_supply - supported power rails to supply memory arrays
+ * %MSM_APM_SUPPLY_APCC:	to enable selection of VDD_APCC rail as supply
+ * %MSM_APM_SUPPLY_MX:		to enable selection of VDD_MX rail as supply
+ */
+enum msm_apm_supply {
+	MSM_APM_SUPPLY_APCC,
+	MSM_APM_SUPPLY_MX,
+};
+
+/* Handle used to identify an APM controller device  */
+struct msm_apm_ctrl_dev;
+
+#ifdef CONFIG_QCOM_APM
+struct msm_apm_ctrl_dev *msm_apm_ctrl_dev_get(struct device *dev);
+int msm_apm_set_supply(struct msm_apm_ctrl_dev *ctrl_dev,
+		       enum msm_apm_supply supply);
+int msm_apm_get_supply(struct msm_apm_ctrl_dev *ctrl_dev);
+
+#else
+static inline struct msm_apm_ctrl_dev *msm_apm_ctrl_dev_get(struct device *dev)
+{ return ERR_PTR(-EPERM); }
+static inline int msm_apm_set_supply(struct msm_apm_ctrl_dev *ctrl_dev,
+		       enum msm_apm_supply supply)
+{ return -EPERM; }
+static inline int msm_apm_get_supply(struct msm_apm_ctrl_dev *ctrl_dev)
+{ return -EPERM; }
+#endif
+#endif
