cpufreq: brcmstb-avs-cpufreq: AVS CPUfreq driver for Broadcom STB SoCs

This driver supports voltage and frequency scaling on Broadcom STB SoCs
using AVS firmware with DFS and DVFS support.

Actual frequency or voltage scaling is done exclusively by the AVS
firmware. The driver merely provides a standard CPUfreq interface to
other kernel components and userland, and instructs the AVS firmware to
perform frequency or voltage changes on its behalf.
Signed-off-by: Markus Mayer <mmayer@broadcom.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

MAINTAINERS

@@ -2744,6 +2744,7 @@ M:	bcm-kernel-feedback-list@broadcom.com
 L:	linux-pm@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/cpufreq/brcm,stb-avs-cpu-freq.txt
+F:	drivers/cpufreq/brcmstb*
 
 BROADCOM SPECIFIC AMBA DRIVER (BCMA)
 M:	Rafał Miłecki <zajec5@gmail.com>

drivers/cpufreq/Kconfig.arm

@@ -12,6 +12,17 @@ config ARM_BIG_LITTLE_CPUFREQ
 	help
 	  This enables the Generic CPUfreq driver for ARM big.LITTLE platforms.
 
+config ARM_BRCMSTB_AVS_CPUFREQ
+	tristate "Broadcom STB AVS CPUfreq driver"
+	depends on ARCH_BRCMSTB || COMPILE_TEST
+	default y
+	help
+	  Some Broadcom STB SoCs use a co-processor running proprietary firmware
+	  ("AVS") to handle voltage and frequency scaling. This driver provides
+	  a standard CPUfreq interface to to the firmware.
+
+	  Say Y, if you have a Broadcom SoC with AVS support for DFS or DVFS.
+
 config ARM_DT_BL_CPUFREQ
 	tristate "Generic probing via DT for ARM big LITTLE CPUfreq driver"
 	depends on ARM_BIG_LITTLE_CPUFREQ && OF

drivers/cpufreq/Makefile

@@ -51,6 +51,7 @@ obj-$(CONFIG_ARM_BIG_LITTLE_CPUFREQ)	+= arm_big_little.o
 # LITTLE drivers, so that it is probed last.
 obj-$(CONFIG_ARM_DT_BL_CPUFREQ)		+= arm_big_little_dt.o
 
+obj-$(CONFIG_ARM_BRCMSTB_AVS_CPUFREQ)	+= brcmstb-avs-cpufreq.o
 obj-$(CONFIG_ARCH_DAVINCI)		+= davinci-cpufreq.o
 obj-$(CONFIG_UX500_SOC_DB8500)		+= dbx500-cpufreq.o
 obj-$(CONFIG_ARM_EXYNOS5440_CPUFREQ)	+= exynos5440-cpufreq.o

drivers/cpufreq/brcmstb-avs-cpufreq.c

+/*
+ * CPU frequency scaling for Broadcom SoCs with AVS firmware that
+ * supports DVS or DVFS
+ *
+ * Copyright (c) 2016 Broadcom
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+/*
+ * "AVS" is the name of a firmware developed at Broadcom. It derives
+ * its name from the technique called "Adaptive Voltage Scaling".
+ * Adaptive voltage scaling was the original purpose of this firmware.
+ * The AVS firmware still supports "AVS mode", where all it does is
+ * adaptive voltage scaling. However, on some newer Broadcom SoCs, the
+ * AVS Firmware, despite its unchanged name, also supports DFS mode and
+ * DVFS mode.
+ *
+ * In the context of this document and the related driver, "AVS" by
+ * itself always means the Broadcom firmware and never refers to the
+ * technique called "Adaptive Voltage Scaling".
+ *
+ * The Broadcom STB AVS CPUfreq driver provides voltage and frequency
+ * scaling on Broadcom SoCs using AVS firmware with support for DFS and
+ * DVFS. The AVS firmware is running on its own co-processor. The
+ * driver supports both uniprocessor (UP) and symmetric multiprocessor
+ * (SMP) systems which share clock and voltage across all CPUs.
+ *
+ * Actual voltage and frequency scaling is done solely by the AVS
+ * firmware. This driver does not change frequency or voltage itself.
+ * It provides a standard CPUfreq interface to the rest of the kernel
+ * and to userland. It interfaces with the AVS firmware to effect the
+ * requested changes and to report back the current system status in a
+ * way that is expected by existing tools.
+ */
+
+#include <linux/cpufreq.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/semaphore.h>
+
+/* Max number of arguments AVS calls take */
+#define AVS_MAX_CMD_ARGS	4
+/*
+ * This macro is used to generate AVS parameter register offsets. For
+ * x >= AVS_MAX_CMD_ARGS, it returns 0 to protect against accidental memory
+ * access outside of the parameter range. (Offset 0 is the first parameter.)
+ */
+#define AVS_PARAM_MULT(x)	((x) < AVS_MAX_CMD_ARGS ? (x) : 0)
+
+/* AVS Mailbox Register offsets */
+#define AVS_MBOX_COMMAND	0x00
+#define AVS_MBOX_STATUS		0x04
+#define AVS_MBOX_VOLTAGE0	0x08
+#define AVS_MBOX_TEMP0		0x0c
+#define AVS_MBOX_PV0		0x10
+#define AVS_MBOX_MV0		0x14
+#define AVS_MBOX_PARAM(x)	(0x18 + AVS_PARAM_MULT(x) * sizeof(u32))
+#define AVS_MBOX_REVISION	0x28
+#define AVS_MBOX_PSTATE		0x2c
+#define AVS_MBOX_HEARTBEAT	0x30
+#define AVS_MBOX_MAGIC		0x34
+#define AVS_MBOX_SIGMA_HVT	0x38
+#define AVS_MBOX_SIGMA_SVT	0x3c
+#define AVS_MBOX_VOLTAGE1	0x40
+#define AVS_MBOX_TEMP1		0x44
+#define AVS_MBOX_PV1		0x48
+#define AVS_MBOX_MV1		0x4c
+#define AVS_MBOX_FREQUENCY	0x50
+
+/* AVS Commands */
+#define AVS_CMD_AVAILABLE	0x00
+#define AVS_CMD_DISABLE		0x10
+#define AVS_CMD_ENABLE		0x11
+#define AVS_CMD_S2_ENTER	0x12
+#define AVS_CMD_S2_EXIT		0x13
+#define AVS_CMD_BBM_ENTER	0x14
+#define AVS_CMD_BBM_EXIT	0x15
+#define AVS_CMD_S3_ENTER	0x16
+#define AVS_CMD_S3_EXIT		0x17
+#define AVS_CMD_BALANCE		0x18
+/* PMAP and P-STATE commands */
+#define AVS_CMD_GET_PMAP	0x30
+#define AVS_CMD_SET_PMAP	0x31
+#define AVS_CMD_GET_PSTATE	0x40
+#define AVS_CMD_SET_PSTATE	0x41
+
+/* Different modes AVS supports (for GET_PMAP/SET_PMAP) */
+#define AVS_MODE_AVS		0x0
+#define AVS_MODE_DFS		0x1
+#define AVS_MODE_DVS		0x2
+#define AVS_MODE_DVFS		0x3
+
+/*
+ * PMAP parameter p1
+ * unused:31-24, mdiv_p0:23-16, unused:15-14, pdiv:13-10 , ndiv_int:9-0
+ */
+#define NDIV_INT_SHIFT		0
+#define NDIV_INT_MASK		0x3ff
+#define PDIV_SHIFT		10
+#define PDIV_MASK		0xf
+#define MDIV_P0_SHIFT		16
+#define MDIV_P0_MASK		0xff
+/*
+ * PMAP parameter p2
+ * mdiv_p4:31-24, mdiv_p3:23-16, mdiv_p2:15:8, mdiv_p1:7:0
+ */
+#define MDIV_P1_SHIFT		0
+#define MDIV_P1_MASK		0xff
+#define MDIV_P2_SHIFT		8
+#define MDIV_P2_MASK		0xff
+#define MDIV_P3_SHIFT		16
+#define MDIV_P3_MASK		0xff
+#define MDIV_P4_SHIFT		24
+#define MDIV_P4_MASK		0xff
+
+/* Different P-STATES AVS supports (for GET_PSTATE/SET_PSTATE) */
+#define AVS_PSTATE_P0		0x0
+#define AVS_PSTATE_P1		0x1
+#define AVS_PSTATE_P2		0x2
+#define AVS_PSTATE_P3		0x3
+#define AVS_PSTATE_P4		0x4
+#define AVS_PSTATE_MAX		AVS_PSTATE_P4
+
+/* CPU L2 Interrupt Controller Registers */
+#define AVS_CPU_L2_SET0		0x04
+#define AVS_CPU_L2_INT_MASK	BIT(31)
+
+/* AVS Command Status Values */
+#define AVS_STATUS_CLEAR	0x00
+/* Command/notification accepted */
+#define AVS_STATUS_SUCCESS	0xf0
+/* Command/notification rejected */
+#define AVS_STATUS_FAILURE	0xff
+/* Invalid command/notification (unknown) */
+#define AVS_STATUS_INVALID	0xf1
+/* Non-AVS modes are not supported */
+#define AVS_STATUS_NO_SUPP	0xf2
+/* Cannot set P-State until P-Map supplied */
+#define AVS_STATUS_NO_MAP	0xf3
+/* Cannot change P-Map after initial P-Map set */
+#define AVS_STATUS_MAP_SET	0xf4
+/* Max AVS status; higher numbers are used for debugging */
+#define AVS_STATUS_MAX		0xff
+
+/* Other AVS related constants */
+#define AVS_LOOP_LIMIT		10000
+#define AVS_TIMEOUT		300 /* in ms; expected completion is < 10ms */
+#define AVS_FIRMWARE_MAGIC	0xa11600d1
+
+#define BRCM_AVS_CPUFREQ_PREFIX	"brcmstb-avs"
+#define BRCM_AVS_CPUFREQ_NAME	BRCM_AVS_CPUFREQ_PREFIX "-cpufreq"
+#define BRCM_AVS_CPU_DATA	"brcm,avs-cpu-data-mem"
+#define BRCM_AVS_CPU_INTR	"brcm,avs-cpu-l2-intr"
+#define BRCM_AVS_HOST_INTR	"sw_intr"
+
+struct pmap {
+	unsigned int mode;
+	unsigned int p1;
+	unsigned int p2;
+	unsigned int state;
+};
+
+struct private_data {
+	void __iomem *base;
+	void __iomem *avs_intr_base;
+	struct device *dev;
+	struct completion done;
+	struct semaphore sem;
+	struct pmap pmap;
+};
+
+static void __iomem *__map_region(const char *name)
+{
+	struct device_node *np;
+	void __iomem *ptr;
+
+	np = of_find_compatible_node(NULL, NULL, name);
+	if (!np)
+		return NULL;
+
+	ptr = of_iomap(np, 0);
+	of_node_put(np);
+
+	return ptr;
+}
+
+static int __issue_avs_command(struct private_data *priv, int cmd, bool is_send,
+			       u32 args[])
+{
+	unsigned long time_left = msecs_to_jiffies(AVS_TIMEOUT);
+	void __iomem *base = priv->base;
+	unsigned int i;
+	int ret;
+	u32 val;
+
+	ret = down_interruptible(&priv->sem);
+	if (ret)
+		return ret;
+
+	/*
+	 * Make sure no other command is currently running: cmd is 0 if AVS
+	 * co-processor is idle. Due to the guard above, we should almost never
+	 * have to wait here.
+	 */
+	for (i = 0, val = 1; val != 0 && i < AVS_LOOP_LIMIT; i++)
+		val = readl(base + AVS_MBOX_COMMAND);
+
+	/* Give the caller a chance to retry if AVS is busy. */
+	if (i == AVS_LOOP_LIMIT) {
+		ret = -EAGAIN;
+		goto out;
+	}
+
+	/* Clear status before we begin. */
+	writel(AVS_STATUS_CLEAR, base + AVS_MBOX_STATUS);
+
+	/* We need to send arguments for this command. */
+	if (args && is_send) {
+		for (i = 0; i < AVS_MAX_CMD_ARGS; i++)
+			writel(args[i], base + AVS_MBOX_PARAM(i));
+	}
+
+	/* Protect from spurious interrupts. */
+	reinit_completion(&priv->done);
+
+	/* Now issue the command & tell firmware to wake up to process it. */
+	writel(cmd, base + AVS_MBOX_COMMAND);
+	writel(AVS_CPU_L2_INT_MASK, priv->avs_intr_base + AVS_CPU_L2_SET0);
+
+	/* Wait for AVS co-processor to finish processing the command. */
+	time_left = wait_for_completion_timeout(&priv->done, time_left);
+
+	/*
+	 * If the AVS status is not in the expected range, it means AVS didn't
+	 * complete our command in time, and we return an error. Also, if there
+	 * is no "time left", we timed out waiting for the interrupt.
+	 */
+	val = readl(base + AVS_MBOX_STATUS);
+	if (time_left == 0 || val == 0 || val > AVS_STATUS_MAX) {
+		dev_err(priv->dev, "AVS command %#x didn't complete in time\n",
+			cmd);
+		dev_err(priv->dev, "    Time left: %u ms, AVS status: %#x\n",
+			jiffies_to_msecs(time_left), val);
+		ret = -ETIMEDOUT;
+		goto out;
+	}
+
+	/* This command returned arguments, so we read them back. */
+	if (args && !is_send) {
+		for (i = 0; i < AVS_MAX_CMD_ARGS; i++)
+			args[i] = readl(base + AVS_MBOX_PARAM(i));
+	}
+
+	/* Clear status to tell AVS co-processor we are done. */
+	writel(AVS_STATUS_CLEAR, base + AVS_MBOX_STATUS);
+
+	/* Convert firmware errors to errno's as much as possible. */
+	switch (val) {
+	case AVS_STATUS_INVALID:
+		ret = -EINVAL;
+		break;
+	case AVS_STATUS_NO_SUPP:
+		ret = -ENOTSUPP;
+		break;
+	case AVS_STATUS_NO_MAP:
+		ret = -ENOENT;
+		break;
+	case AVS_STATUS_MAP_SET:
+		ret = -EEXIST;
+		break;
+	case AVS_STATUS_FAILURE:
+		ret = -EIO;
+		break;
+	}
+
+out:
+	up(&priv->sem);
+
+	return ret;
+}
+
+static irqreturn_t irq_handler(int irq, void *data)
+{
+	struct private_data *priv = data;
+
+	/* AVS command completed execution. Wake up __issue_avs_command(). */
+	complete(&priv->done);
+
+	return IRQ_HANDLED;
+}
+
+static char *brcm_avs_mode_to_string(unsigned int mode)
+{
+	switch (mode) {
+	case AVS_MODE_AVS:
+		return "AVS";
+	case AVS_MODE_DFS:
+		return "DFS";
+	case AVS_MODE_DVS:
+		return "DVS";
+	case AVS_MODE_DVFS:
+		return "DVFS";
+	}
+	return NULL;
+}
+
+static void brcm_avs_parse_p1(u32 p1, unsigned int *mdiv_p0, unsigned int *pdiv,
+			      unsigned int *ndiv)
+{
+	*mdiv_p0 = (p1 >> MDIV_P0_SHIFT) & MDIV_P0_MASK;
+	*pdiv = (p1 >> PDIV_SHIFT) & PDIV_MASK;
+	*ndiv = (p1 >> NDIV_INT_SHIFT) & NDIV_INT_MASK;
+}
+
+static void brcm_avs_parse_p2(u32 p2, unsigned int *mdiv_p1,
+			      unsigned int *mdiv_p2, unsigned int *mdiv_p3,
+			      unsigned int *mdiv_p4)
+{
+	*mdiv_p4 = (p2 >> MDIV_P4_SHIFT) & MDIV_P4_MASK;
+	*mdiv_p3 = (p2 >> MDIV_P3_SHIFT) & MDIV_P3_MASK;
+	*mdiv_p2 = (p2 >> MDIV_P2_SHIFT) & MDIV_P2_MASK;
+	*mdiv_p1 = (p2 >> MDIV_P1_SHIFT) & MDIV_P1_MASK;
+}
+
+static int brcm_avs_get_pmap(struct private_data *priv, struct pmap *pmap)
+{
+	u32 args[AVS_MAX_CMD_ARGS];
+	int ret;
+
+	ret = __issue_avs_command(priv, AVS_CMD_GET_PMAP, false, args);
+	if (ret || !pmap)
+		return ret;
+
+	pmap->mode = args[0];
+	pmap->p1 = args[1];
+	pmap->p2 = args[2];
+	pmap->state = args[3];
+
+	return 0;
+}
+
+static int brcm_avs_set_pmap(struct private_data *priv, struct pmap *pmap)
+{
+	u32 args[AVS_MAX_CMD_ARGS];
+
+	args[0] = pmap->mode;
+	args[1] = pmap->p1;
+	args[2] = pmap->p2;
+	args[3] = pmap->state;
+
+	return __issue_avs_command(priv, AVS_CMD_SET_PMAP, true, args);
+}
+
+static int brcm_avs_get_pstate(struct private_data *priv, unsigned int *pstate)
+{
+	u32 args[AVS_MAX_CMD_ARGS];
+	int ret;
+
+	ret = __issue_avs_command(priv, AVS_CMD_GET_PSTATE, false, args);
+	if (ret)
+		return ret;
+	*pstate = args[0];
+
+	return 0;
+}
+
+static int brcm_avs_set_pstate(struct private_data *priv, unsigned int pstate)
+{
+	u32 args[AVS_MAX_CMD_ARGS];
+
+	args[0] = pstate;
+
+	return __issue_avs_command(priv, AVS_CMD_SET_PSTATE, true, args);
+}
+
+static unsigned long brcm_avs_get_voltage(void __iomem *base)
+{
+	return readl(base + AVS_MBOX_VOLTAGE1);
+}
+
+static unsigned long brcm_avs_get_frequency(void __iomem *base)
+{
+	return readl(base + AVS_MBOX_FREQUENCY) * 1000;	/* in kHz */
+}
+
+/*
+ * We determine which frequencies are supported by cycling through all P-states
+ * and reading back what frequency we are running at for each P-state.
+ */
+static struct cpufreq_frequency_table *
+brcm_avs_get_freq_table(struct device *dev, struct private_data *priv)
+{
+	struct cpufreq_frequency_table *table;
+	unsigned int pstate;
+	int i, ret;
+
+	/* Remember P-state for later */
+	ret = brcm_avs_get_pstate(priv, &pstate);
+	if (ret)
+		return ERR_PTR(ret);
+
+	table = devm_kzalloc(dev, (AVS_PSTATE_MAX + 1) * sizeof(*table),
+			     GFP_KERNEL);
+	if (!table)
+		return ERR_PTR(-ENOMEM);
+
+	for (i = AVS_PSTATE_P0; i <= AVS_PSTATE_MAX; i++) {
+		ret = brcm_avs_set_pstate(priv, i);
+		if (ret)
+			return ERR_PTR(ret);
+		table[i].frequency = brcm_avs_get_frequency(priv->base);
+		table[i].driver_data = i;
+	}
+	table[i].frequency = CPUFREQ_TABLE_END;
+
+	/* Restore P-state */
+	ret = brcm_avs_set_pstate(priv, pstate);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return table;
+}
+
+/*
+ * To ensure the right firmware is running we need to
+ *    - check the MAGIC matches what we expect
+ *    - brcm_avs_get_pmap() doesn't return -ENOTSUPP or -EINVAL
+ * We need to set up our interrupt handling before calling brcm_avs_get_pmap()!
+ */
+static bool brcm_avs_is_firmware_loaded(struct private_data *priv)
+{
+	u32 magic;
+	int rc;
+
+	rc = brcm_avs_get_pmap(priv, NULL);
+	magic = readl(priv->base + AVS_MBOX_MAGIC);
+
+	return (magic == AVS_FIRMWARE_MAGIC) && (rc != -ENOTSUPP) &&
+		(rc != -EINVAL);
+}
+
+static unsigned int brcm_avs_cpufreq_get(unsigned int cpu)
+{
+	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
+	struct private_data *priv = policy->driver_data;
+
+	return brcm_avs_get_frequency(priv->base);
+}
+
+static int brcm_avs_target_index(struct cpufreq_policy *policy,
+				 unsigned int index)
+{
+	return brcm_avs_set_pstate(policy->driver_data,
+				  policy->freq_table[index].driver_data);
+}
+
+static int brcm_avs_suspend(struct cpufreq_policy *policy)
+{
+	struct private_data *priv = policy->driver_data;
+
+	return brcm_avs_get_pmap(priv, &priv->pmap);
+}
+
+static int brcm_avs_resume(struct cpufreq_policy *policy)
+{
+	struct private_data *priv = policy->driver_data;
+	int ret;
+
+	ret = brcm_avs_set_pmap(priv, &priv->pmap);
+	if (ret == -EEXIST) {
+		struct platform_device *pdev  = cpufreq_get_driver_data();
+		struct device *dev = &pdev->dev;
+
+		dev_warn(dev, "PMAP was already set\n");
+		ret = 0;
+	}
+
+	return ret;
+}
+
+/*
+ * All initialization code that we only want to execute once goes here. Setup
+ * code that can be re-tried on every core (if it failed before) can go into
+ * brcm_avs_cpufreq_init().
+ */
+static int brcm_avs_prepare_init(struct platform_device *pdev)
+{
+	struct private_data *priv;
+	struct device *dev;
+	int host_irq, ret;
+
+	dev = &pdev->dev;
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->dev = dev;
+	sema_init(&priv->sem, 1);
+	init_completion(&priv->done);
+	platform_set_drvdata(pdev, priv);
+
+	priv->base = __map_region(BRCM_AVS_CPU_DATA);
+	if (!priv->base) {
+		dev_err(dev, "Couldn't find property %s in device tree.\n",
+			BRCM_AVS_CPU_DATA);
+		return -ENOENT;
+	}
+
+	priv->avs_intr_base = __map_region(BRCM_AVS_CPU_INTR);
+	if (!priv->avs_intr_base) {
+		dev_err(dev, "Couldn't find property %s in device tree.\n",
+			BRCM_AVS_CPU_INTR);
+		ret = -ENOENT;
+		goto unmap_base;
+	}
+
+	host_irq = platform_get_irq_byname(pdev, BRCM_AVS_HOST_INTR);
+	if (host_irq < 0) {
+		dev_err(dev, "Couldn't find interrupt %s -- %d\n",
+			BRCM_AVS_HOST_INTR, host_irq);
+		ret = host_irq;
+		goto unmap_intr_base;
+	}
+
+	ret = devm_request_irq(dev, host_irq, irq_handler, IRQF_TRIGGER_RISING,
+			       BRCM_AVS_HOST_INTR, priv);
+	if (ret) {
+		dev_err(dev, "IRQ request failed: %s (%d) -- %d\n",
+			BRCM_AVS_HOST_INTR, host_irq, ret);
+		goto unmap_intr_base;
+	}
+
+	if (brcm_avs_is_firmware_loaded(priv))
+		return 0;
+
+	dev_err(dev, "AVS firmware is not loaded or doesn't support DVFS\n");
+	ret = -ENODEV;
+
+unmap_intr_base:
+	iounmap(priv->avs_intr_base);
+unmap_base:
+	iounmap(priv->base);
+	platform_set_drvdata(pdev, NULL);
+
+	return ret;
+}
+
+static int brcm_avs_cpufreq_init(struct cpufreq_policy *policy)
+{
+	struct cpufreq_frequency_table *freq_table;
+	struct platform_device *pdev;
+	struct private_data *priv;
+	struct device *dev;
+	int ret;
+
+	pdev = cpufreq_get_driver_data();
+	priv = platform_get_drvdata(pdev);
+	policy->driver_data = priv;
+	dev = &pdev->dev;
+
+	freq_table = brcm_avs_get_freq_table(dev, priv);
+	if (IS_ERR(freq_table)) {
+		ret = PTR_ERR(freq_table);
+		dev_err(dev, "Couldn't determine frequency table (%d).\n", ret);
+		return ret;
+	}
+
+	ret = cpufreq_table_validate_and_show(policy, freq_table);
+	if (ret) {
+		dev_err(dev, "invalid frequency table: %d\n", ret);
+		return ret;
+	}
+
+	/* All cores share the same clock and thus the same policy. */
+	cpumask_setall(policy->cpus);
+
+	ret = __issue_avs_command(priv, AVS_CMD_ENABLE, false, NULL);
+	if (!ret) {
+		unsigned int pstate;
+
+		ret = brcm_avs_get_pstate(priv, &pstate);
+		if (!ret) {
+			policy->cur = freq_table[pstate].frequency;
+			dev_info(dev, "registered\n");
+			return 0;
+		}
+	}
+
+	dev_err(dev, "couldn't initialize driver (%d)\n", ret);
+
+	return ret;
+}
+
+static ssize_t show_brcm_avs_pstate(struct cpufreq_policy *policy, char *buf)
+{
+	struct private_data *priv = policy->driver_data;
+	unsigned int pstate;
+
+	if (brcm_avs_get_pstate(priv, &pstate))
+		return sprintf(buf, "<unknown>\n");
+
+	return sprintf(buf, "%u\n", pstate);
+}
+
+static ssize_t show_brcm_avs_mode(struct cpufreq_policy *policy, char *buf)
+{
+	struct private_data *priv = policy->driver_data;
+	struct pmap pmap;
+
+	if (brcm_avs_get_pmap(priv, &pmap))
+		return sprintf(buf, "<unknown>\n");
+
+	return sprintf(buf, "%s %u\n", brcm_avs_mode_to_string(pmap.mode),
+		pmap.mode);
+}
+
+static ssize_t show_brcm_avs_pmap(struct cpufreq_policy *policy, char *buf)
+{
+	unsigned int mdiv_p0, mdiv_p1, mdiv_p2, mdiv_p3, mdiv_p4;
+	struct private_data *priv = policy->driver_data;
+	unsigned int ndiv, pdiv;
+	struct pmap pmap;
+
+	if (brcm_avs_get_pmap(priv, &pmap))
+		return sprintf(buf, "<unknown>\n");
+
+	brcm_avs_parse_p1(pmap.p1, &mdiv_p0, &pdiv, &ndiv);
+	brcm_avs_parse_p2(pmap.p2, &mdiv_p1, &mdiv_p2, &mdiv_p3, &mdiv_p4);
+
+	return sprintf(buf, "0x%08x 0x%08x %u %u %u %u %u %u %u\n",
+		pmap.p1, pmap.p2, ndiv, pdiv, mdiv_p0, mdiv_p1, mdiv_p2,
+		mdiv_p3, mdiv_p4);
+}
+
+static ssize_t show_brcm_avs_voltage(struct cpufreq_policy *policy, char *buf)
+{
+	struct private_data *priv = policy->driver_data;
+
+	return sprintf(buf, "0x%08lx\n", brcm_avs_get_voltage(priv->base));
+}
+
+static ssize_t show_brcm_avs_frequency(struct cpufreq_policy *policy, char *buf)
+{
+	struct private_data *priv = policy->driver_data;
+
+	return sprintf(buf, "0x%08lx\n", brcm_avs_get_frequency(priv->base));
+}
+
+cpufreq_freq_attr_ro(brcm_avs_pstate);
+cpufreq_freq_attr_ro(brcm_avs_mode);
+cpufreq_freq_attr_ro(brcm_avs_pmap);
+cpufreq_freq_attr_ro(brcm_avs_voltage);
+cpufreq_freq_attr_ro(brcm_avs_frequency);
+
+struct freq_attr *brcm_avs_cpufreq_attr[] = {
+	&cpufreq_freq_attr_scaling_available_freqs,
+	&brcm_avs_pstate,
+	&brcm_avs_mode,
+	&brcm_avs_pmap,
+	&brcm_avs_voltage,
+	&brcm_avs_frequency,
+	NULL
+};
+
+static struct cpufreq_driver brcm_avs_driver = {
+	.flags		= CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+	.verify		= cpufreq_generic_frequency_table_verify,
+	.target_index	= brcm_avs_target_index,
+	.get		= brcm_avs_cpufreq_get,
+	.suspend	= brcm_avs_suspend,
+	.resume		= brcm_avs_resume,
+	.init		= brcm_avs_cpufreq_init,
+	.attr		= brcm_avs_cpufreq_attr,
+	.name		= BRCM_AVS_CPUFREQ_PREFIX,
+};
+
+static int brcm_avs_cpufreq_probe(struct platform_device *pdev)
+{
+	int ret;
+
+	ret = brcm_avs_prepare_init(pdev);
+	if (ret)
+		return ret;
+
+	brcm_avs_driver.driver_data = pdev;
+
+	return cpufreq_register_driver(&brcm_avs_driver);
+}
+
+static int brcm_avs_cpufreq_remove(struct platform_device *pdev)
+{
+	struct private_data *priv;
+	int ret;
+
+	ret = cpufreq_unregister_driver(&brcm_avs_driver);
+	if (ret)
+		return ret;
+
+	priv = platform_get_drvdata(pdev);
+	iounmap(priv->base);
+	iounmap(priv->avs_intr_base);
+	platform_set_drvdata(pdev, NULL);
+
+	return 0;
+}
+
+static const struct of_device_id brcm_avs_cpufreq_match[] = {
+	{ .compatible = BRCM_AVS_CPU_DATA },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, brcm_avs_cpufreq_match);
+
+static struct platform_driver brcm_avs_cpufreq_platdrv = {
+	.driver = {
+		.name	= BRCM_AVS_CPUFREQ_NAME,
+		.of_match_table = brcm_avs_cpufreq_match,
+	},
+	.probe		= brcm_avs_cpufreq_probe,
+	.remove		= brcm_avs_cpufreq_remove,
+};
+module_platform_driver(brcm_avs_cpufreq_platdrv);
+
+MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>");
+MODULE_DESCRIPTION("CPUfreq driver for Broadcom STB AVS");
+MODULE_LICENSE("GPL");