hwmon:tegra:tsensor driver added

Tegra integrated temperature sensor(tsensor) driver added
 - TH3 counter < current counter causes hardware reset
 - TH2 counter < current counter causes CPU clock to be halved
 - sysfs interface provided for select operations
 - interrupts TH1 TH2 and TH3 working
 - used recommended N,M and clk source settings
 - tsensor counter to temperature conversion added
   tsensor1 counter being used for temperature computations.

Bug 661228

Original-Change-Id: I0fa405c0f542d1b215162291bd913a9ccd55a0f5
Reviewed-on: http://git-master/r/36083
Tested-by: Bitan Biswas <bbiswas@nvidia.com>
Reviewed-by: Bitan Biswas <bbiswas@nvidia.com>

Rebase-Id: R3c910b4fdc630ffee2135d3d649e25015d2b7206

1 files changed, 1686 insertions, 0 deletions

diff --git a/drivers/hwmon/tegra-tsensor.c b/drivers/hwmon/tegra-tsensor.c
new file mode 100644
index 000000000000..b3edeb3c844e
--- /dev/null
+++ b/drivers/hwmon/tegra-tsensor.c
@@ -0,0 +1,1686 @@
+/*
+ * NVIDIA Tegra SOC - temperature sensor driver
+ *
+ * Copyright (C) 2011 NVIDIA Corporation
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+
+#if 0
+#define VERBOSE_DEBUG
+#define DEBUG
+#endif
+
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/hwmon.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <linux/irqreturn.h>
+#include <linux/err.h>
+#include <linux/spinlock.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/regulator/consumer.h>
+#include <linux/delay.h>
+
+#include <mach/iomap.h>
+#include <mach/clk.h>
+#include <mach/delay.h>
+#include <mach/tsensor.h>
+
+/* We have multiple tsensor instances with following registers */
+#define SENSOR_CFG0				0x40
+#define SENSOR_CFG1				0x48
+#define SENSOR_CFG2				0x4c
+#define SENSOR_STATUS0				0x58
+#define SENSOR_TS_STATUS1			0x5c
+#define SENSOR_TS_STATUS2			0x60
+
+/* interrupt mask in tsensor status register */
+#define TSENSOR_SENSOR_X_STATUS0_0_INTR_MASK	(1 << 8)
+
+#define SENSOR_CFG0_M_MASK			0xffff
+#define SENSOR_CFG0_M_SHIFT			8
+#define SENSOR_CFG0_N_MASK			0xff
+#define SENSOR_CFG0_N_SHIFT			24
+#define SENSOR_CFG0_RST_INTR_SHIFT		6
+#define SENSOR_CFG0_HW_DIV2_INTR_SHIFT		5
+#define SENSOR_CFG0_OVERFLOW_INTR		4
+#define SENSOR_CFG0_RST_ENABLE_SHIFT		2
+#define SENSOR_CFG0_HW_DIV2_ENABLE_SHIFT	1
+#define SENSOR_CFG0_STOP_SHIFT			0
+
+#define SENSOR_CFG_X_TH_X_MASK			0xffff
+#define SENSOR_CFG1_TH2_SHIFT			16
+#define SENSOR_CFG1_TH1_SHIFT			0
+#define SENSOR_CFG2_TH3_SHIFT			0
+#define SENSOR_CFG2_TH0_SHIFT			16
+
+#define SENSOR_STATUS_AVG_VALID_SHIFT		10
+#define SENSOR_STATUS_CURR_VALID_SHIFT		9
+
+#define STATE_MASK				0x7
+#define STATUS0_STATE_SHIFT			0
+#define STATUS0_PREV_STATE_SHIFT		4
+
+#define LOCAL_STR_SIZE1				60
+#define MAX_STR_LINE				100
+#define MAX_TSENSOR_LOOP1			(1000 * 2)
+
+/* fuse spare bits are used to get Tj-ADT values */
+#define FUSE_SPARE_BIT_0_0			0x244
+#define FUSE_SPARE_BIT_6_0			0x25c
+#define FUSE_SPARE_BIT_20_0			0x294
+#define NUM_FUSE_REGS				7
+
+#define FUSE_TSENSOR_CALIB_0			0x198
+
+#define TSENSOR_COUNTER_TOLERANCE		100
+
+#define SENSOR_CTRL_RST_SHIFT			1
+#define RST_SRC_MASK				0x7
+#define RST_SRC_SENSOR				2
+#define TEGRA_REV_REG_OFFSET			0x804
+#define CCLK_G_BURST_POLICY_REG_REL_OFFSET	0x368
+#define TSENSOR_SLOWDOWN_BIT			23
+
+/* macros used for temperature calculations */
+#define get_temperature_int(X)			((X) / 100)
+#define get_temperature_fraction(X)		(((int)(abs(X))) % 100)
+#define get_temperature_round(X)		DIV_ROUND_CLOSEST(X, 100)
+
+/* tsensor states */
+enum ts_state {
+	TS_INVALID = 0,
+	TS_LEVEL0,
+	TS_LEVEL1,
+	TS_LEVEL2,
+	TS_LEVEL3,
+	TS_OVERFLOW,
+	TS_MAX_STATE = TS_OVERFLOW
+};
+
+/* composite type with tsensor state */
+struct tsensor_state {
+	unsigned int prev_state;
+	unsigned int state;
+};
+
+enum {
+	/* temperature is sensed from 2 points on tegra */
+	TSENSOR_COUNT = 2,
+	/* divide by 2 temperature threshold */
+	DIV2_CELSIUS_TEMP_THRESHOLD_DEFAULT = 70,
+	/* reset chip temperature threshold */
+	RESET_CELSIUS_TEMP_THRESHOLD_DEFAULT = 75,
+	/* tsensor frequency in Hz for clk src CLK_M and divisor=24 */
+	DEFAULT_TSENSOR_CLK_HZ = 500000,
+	DEFAULT_TSENSOR_N = 255,
+	DEFAULT_TSENSOR_M = 500,
+	/* tsensor instance offset */
+	TSENSOR_INSTANCE_OFFSET = 0x40,
+	MIN_THRESHOLD = 0x0,
+	MAX_THRESHOLD = 0xffff,
+	DEFAULT_THRESHOLD_TH0 = MAX_THRESHOLD,
+	DEFAULT_THRESHOLD_TH1 = MAX_THRESHOLD,
+	DEFAULT_THRESHOLD_TH2 = MAX_THRESHOLD,
+	DEFAULT_THRESHOLD_TH3 = MAX_THRESHOLD,
+};
+
+/* constants used to implement sysfs interface */
+enum tsensor_params {
+	TSENSOR_PARAM_TH1 = 0,
+	TSENSOR_PARAM_TH2,
+	TSENSOR_PARAM_TH3,
+	TSENSOR_TEMPERATURE
+};
+
+/*
+ * For each registered chip, we need to keep some data in memory.
+ * The structure is dynamically allocated.
+ */
+struct tegra_tsensor_data {
+	struct device *hwmon_dev;
+	spinlock_t tsensor_lock;
+	struct clk *dev_clk;
+	/* tsensor register space */
+	void __iomem		*base;
+	unsigned long		phys;
+	unsigned long		phys_end;
+	/* pmc register space */
+	void __iomem		*pmc_rst_base;
+	unsigned long		pmc_phys;
+	unsigned long		pmc_phys_end;
+	/* clk register space */
+	void __iomem		*clk_rst_base;
+	int			irq;
+	unsigned int		int_status[TSENSOR_COUNT];
+
+	/* threshold for hardware triggered clock divide by 2 */
+	int div2_temp;
+	/* temperature threshold for hardware triggered system reset */
+	int reset_temp;
+	/* temperature threshold to trigger software interrupt */
+	int sw_intr_temp;
+	int hysteresis;
+	unsigned int ts_state_saved[TSENSOR_COUNT];
+};
+
+enum {
+	TSENSOR_COEFF_SET1 = 0,
+	TSENSOR_COEFF_END
+};
+
+struct tegra_tsensor_coeff {
+	int e_minus6_m;
+	int e_minus6_n;
+	int e_minus2_p;
+};
+
+static struct tegra_tsensor_coeff coeff_table[] = {
+	[TSENSOR_COEFF_SET1] = {
+		-2775,
+		1338811,
+		-730
+	}
+	/* FIXME: add tsensor coefficients after chip characterization */
+};
+
+static unsigned int tsensor_index;
+static char my_fixed_str[LOCAL_STR_SIZE1] = "YYYYYY";
+static char error_str[LOCAL_STR_SIZE1] = "ERROR:";
+static unsigned int fuse_T1, fuse_F1, fuse_T2, fuse_F2;
+static int A_e_minus6, B_e_minus2;
+static int m_e_minus6;
+static int n_e_minus6;
+static int p_e_minus2;
+static unsigned int init_flag;
+
+static int tsensor_count_2_temp(struct tegra_tsensor_data *data,
+	unsigned int count, int *p_temperature);
+static unsigned int tsensor_get_threshold_counter(
+	struct tegra_tsensor_data *data, unsigned int temp);
+
+/* tsensor register access functions */
+
+static void tsensor_writel(struct tegra_tsensor_data *data, u32 val,
+				unsigned long reg)
+{
+	unsigned int reg_offset = reg & 0xffff;
+	unsigned char inst = (reg >> 16) & 0xffff;
+	writel(val, data->base + (inst * TSENSOR_INSTANCE_OFFSET) +
+		reg_offset);
+	return;
+}
+
+static unsigned int tsensor_readl(struct tegra_tsensor_data *data,
+				unsigned long reg)
+{
+	unsigned int reg_offset = reg & 0xffff;
+	unsigned char inst = (reg >> 16) & 0xffff;
+	return readl(data->base +
+		(inst * TSENSOR_INSTANCE_OFFSET) + reg_offset);
+}
+
+static unsigned int tsensor_get_reg_field(
+	struct tegra_tsensor_data *data, unsigned int reg,
+	unsigned int shift, unsigned int mask)
+{
+	unsigned int reg_val;
+	reg_val = tsensor_readl(data, reg);
+	return (reg_val & (mask << shift)) >> shift;
+}
+
+static int tsensor_set_reg_field(
+	struct tegra_tsensor_data *data, unsigned int value,
+	unsigned int reg, unsigned int shift, unsigned int mask)
+{
+	unsigned int reg_val;
+	unsigned int rd_val;
+	reg_val = tsensor_readl(data, reg);
+	reg_val &= ~(mask << shift);
+	reg_val |= ((value & mask) << shift);
+	tsensor_writel(data, reg_val, reg);
+	rd_val = tsensor_readl(data, reg);
+	if (rd_val == reg_val)
+		return 0;
+	else
+		return -EINVAL;
+}
+
+/* enable argument is true to enable reset, false disables pmc reset */
+static void pmc_rst_enable(struct tegra_tsensor_data *data, bool enable)
+{
+	unsigned int val;
+	/* mapped first pmc reg is SENSOR_CTRL */
+	val = readl(data->pmc_rst_base);
+	if (enable)
+		val |= (1 << SENSOR_CTRL_RST_SHIFT);
+	else
+		val &= ~(1 << SENSOR_CTRL_RST_SHIFT);
+	writel(val, data->pmc_rst_base);
+}
+
+/* true returned when pmc reset source is tsensor */
+static bool pmc_check_rst_sensor(struct tegra_tsensor_data *data)
+{
+	unsigned int val;
+	unsigned char src;
+	val = readl(data->pmc_rst_base + 4);
+	src = (unsigned char)(val & RST_SRC_MASK);
+	if (src == RST_SRC_SENSOR)
+		return true;
+	else
+		return false;
+}
+
+/* function to get chip revision */
+static void get_chip_rev(unsigned short *p_id, unsigned short *p_major,
+		unsigned short *p_minor)
+{
+	unsigned int reg;
+
+	reg = readl(IO_TO_VIRT(TEGRA_APB_MISC_BASE) +
+		TEGRA_REV_REG_OFFSET);
+	*p_id = (reg >> 8) & 0xff;
+	*p_major = (reg >> 4) & 0xf;
+	*p_minor = (reg >> 16) & 0xf;
+	pr_info("\n Tegra chip revision for tsensor detected as: "
+		" Chip Id=%d, Major=%d, Minor=%d ", (int)*p_id,
+		(int)*p_major, (int)*p_minor);
+}
+
+/*
+ * function to get chip revision specific tsensor coefficients
+ * obtained after chip characterization
+ */
+static int get_chip_tsensor_coeff(void)
+{
+	unsigned short chip_id, major_rev, minor_rev;
+	unsigned short coeff_index;
+
+	get_chip_rev(&chip_id, &major_rev, &minor_rev);
+	switch (minor_rev) {
+	case 2:
+		pr_info("\n Warning: tsensor coefficient for chip pending ");
+	case 1:
+		coeff_index = TSENSOR_COEFF_SET1;
+		break;
+	default:
+		pr_err("\n Error: tsensor unsupported for detected chip ");
+		return -ENOENT;
+	}
+	m_e_minus6 = coeff_table[coeff_index].e_minus6_m;
+	n_e_minus6 = coeff_table[coeff_index].e_minus6_n;
+	p_e_minus2 = coeff_table[coeff_index].e_minus2_p;
+	return 0;
+}
+
+/* tsensor counter read function */
+static unsigned int tsensor_read_counter(
+	struct tegra_tsensor_data *data, u8 instance,
+	unsigned int *p_counterA, unsigned int *p_counterB)
+{
+	unsigned int status_reg;
+	unsigned int config0;
+	int iter_count = 0;
+	const int max_loop = 50;
+
+	do {
+		config0 = tsensor_readl(data, ((instance << 16) |
+			SENSOR_CFG0));
+		if (config0 & (1 << SENSOR_CFG0_STOP_SHIFT)) {
+			dev_dbg(data->hwmon_dev, "\n Error: tsensor "
+				"counter read with STOP bit not supported ");
+			*p_counterA = 0;
+			*p_counterB = 0;
+			return 0;
+		}
+		status_reg = tsensor_readl(data,
+			(instance << 16) | SENSOR_STATUS0);
+		if ((status_reg & (1 <<
+			SENSOR_STATUS_AVG_VALID_SHIFT)) &&
+			(status_reg & (1 <<
+			SENSOR_STATUS_CURR_VALID_SHIFT))) {
+			*p_counterA = tsensor_readl(data, (instance
+				<< 16) | SENSOR_TS_STATUS1);
+			*p_counterB = tsensor_readl(data, (instance
+				<< 16) | SENSOR_TS_STATUS2);
+			break;
+		}
+		if (!(iter_count % 10))
+			dev_dbg(data->hwmon_dev, "\n retry %d ", iter_count);
+		msleep(1);
+		iter_count++;
+	} while (iter_count < max_loop);
+	if (iter_count == max_loop)
+		return -ENODEV;
+	return 0;
+}
+
+/* tsensor threshold print function */
+static void dump_threshold(struct tegra_tsensor_data *data)
+{
+	int i;
+	unsigned int TH_2_1, TH_0_3;
+	unsigned int curr_avg, min_max;
+	int err;
+	for (i = 0; i < TSENSOR_COUNT; i++) {
+		TH_2_1 = tsensor_readl(data, ((i << 16) | SENSOR_CFG1));
+		TH_0_3 = tsensor_readl(data, ((i << 16) | SENSOR_CFG2));
+		dev_dbg(data->hwmon_dev, "\n Tsensor[%d]: TH_2_1=0x%x, "
+			"TH_0_3=0x%x ", i, TH_2_1, TH_0_3);
+		err = tsensor_read_counter(data, i, &curr_avg, &min_max);
+		if (err < 0)
+			pr_err("\n Error: tsensor %d counter read, "
+				"err=%d ", i, err);
+		else
+			dev_dbg(data->hwmon_dev, "\n Tsensor[%d]: "
+				"curr_avg=0x%x, min_max=0x%x ",
+				i, curr_avg, min_max);
+	}
+}
+
+/* tsensor temperature show function */
+static ssize_t tsensor_show_counters(struct device *dev,
+	struct device_attribute *da, char *buf)
+{
+	int i;
+	unsigned int curr_avg[TSENSOR_COUNT];
+	unsigned int min_max[TSENSOR_COUNT];
+	char err_str[] = "error-sysfs-counter-read\n";
+	char fixed_str[MAX_STR_LINE];
+	struct tegra_tsensor_data *data = dev_get_drvdata(dev);
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	int err;
+	int temp0, temp1;
+
+	if (attr->index == TSENSOR_TEMPERATURE)
+		snprintf(fixed_str, MAX_STR_LINE, "temperature: ");
+	for (i = 0; i < TSENSOR_COUNT; i++) {
+		err = tsensor_read_counter(data, i,
+			&curr_avg[i], &min_max[i]);
+		if (err < 0)
+			goto error;
+	}
+	if (attr->index == TSENSOR_TEMPERATURE) {
+		/* use current counter value to calculate temperature */
+		err = tsensor_count_2_temp(data,
+			((curr_avg[0] & 0xFFFF0000) >> 16), &temp0);
+		dev_vdbg(data->hwmon_dev, "\n %s has curr_avg=0x%x, "
+			"minmax=0x%x, temp0=%d ", __func__,
+			curr_avg[0], min_max[0], temp0);
+		if (err < 0)
+			goto error;
+		err = tsensor_count_2_temp(data,
+			((curr_avg[1] & 0xFFFF0000) >> 16), &temp1);
+		dev_vdbg(data->hwmon_dev, "\n %s has curr_avg=0x%x, "
+			"minmax=0x%x, temp1=%d ", __func__,
+			curr_avg[1], min_max[1], temp1);
+		if (err < 0)
+			goto error;
+		snprintf(buf, (((LOCAL_STR_SIZE1 << 1) + 3) +
+			strlen(fixed_str)),
+			"%s "
+			"[1]: current counter=0x%x, %d.%d"
+			" deg Celsius ", fixed_str,
+			((curr_avg[1] & 0xFFFF0000) >> 16),
+			get_temperature_int(temp1),
+			get_temperature_fraction(temp1));
+	} else {
+		snprintf(buf, ((LOCAL_STR_SIZE1 << 1) + 3) +
+			strlen(fixed_str),
+			"%s[%d %d %d %d] ",
+			fixed_str,
+			((curr_avg[0] >> 16) & 0xffff),
+			(curr_avg[0] & 0xffff),
+			((min_max[0] >> 16) & 0xffff),
+			(min_max[0] & 0xffff));
+	}
+	strcat(buf, "\n");
+	return strlen(buf);
+error:
+	return snprintf(buf, strlen(err_str),
+		"%s", err_str);
+}
+
+/* utility function to check hw clock divide by 2 condition */
+static bool cclkg_check_hwdiv2_sensor(struct tegra_tsensor_data *data)
+{
+	unsigned int val;
+	val = readl(IO_ADDRESS(TEGRA_CLK_RESET_BASE +
+		CCLK_G_BURST_POLICY_REG_REL_OFFSET));
+	if ((1 << TSENSOR_SLOWDOWN_BIT) & val) {
+		dev_err(data->hwmon_dev, "\n Warning: ***** tsensor "
+			"slowdown bit detected ");
+		return true;
+	} else {
+		return false;
+	}
+}
+
+/*
+ * function with table to return register, field shift and mask
+ * values for supported parameters
+ */
+static int get_param_values(unsigned int indx,
+	unsigned int *p_reg, unsigned int *p_sft, unsigned int *p_msk)
+{
+	switch (indx) {
+	case TSENSOR_PARAM_TH1:
+		*p_reg = ((tsensor_index << 16) | SENSOR_CFG1);
+		*p_sft = SENSOR_CFG1_TH1_SHIFT;
+		*p_msk = SENSOR_CFG_X_TH_X_MASK;
+		snprintf(my_fixed_str, LOCAL_STR_SIZE1, "TH1[%d]: ",
+			tsensor_index);
+		break;
+	case TSENSOR_PARAM_TH2:
+		*p_reg = ((tsensor_index << 16) | SENSOR_CFG1);
+		*p_sft = SENSOR_CFG1_TH2_SHIFT;
+		*p_msk = SENSOR_CFG_X_TH_X_MASK;
+		snprintf(my_fixed_str, LOCAL_STR_SIZE1, "TH2[%d]: ",
+			tsensor_index);
+		break;
+	case TSENSOR_PARAM_TH3:
+		*p_reg = ((tsensor_index << 16) | SENSOR_CFG2);
+		*p_sft = SENSOR_CFG2_TH3_SHIFT;
+		*p_msk = SENSOR_CFG_X_TH_X_MASK;
+		snprintf(my_fixed_str, LOCAL_STR_SIZE1, "TH3[%d]: ",
+			tsensor_index);
+		break;
+	default:
+		return -ENOENT;
+	}
+	return 0;
+}
+
+/* tsensor driver sysfs show function */
+static ssize_t show_tsensor_param(struct device *dev,
+				struct device_attribute *da,
+				char *buf)
+{
+	unsigned int val;
+	struct tegra_tsensor_data *data = dev_get_drvdata(dev);
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	unsigned int reg;
+	unsigned int sft;
+	unsigned int msk;
+	int err;
+
+	err = get_param_values(attr->index, &reg, &sft, &msk);
+	if (err < 0)
+		goto labelErr;
+	val = tsensor_get_reg_field(data, reg, sft, msk);
+	snprintf(buf, LOCAL_STR_SIZE1 + strlen(my_fixed_str), "%s%d",
+		my_fixed_str, val);
+	strcat(buf, "\n");
+	return strlen(buf);
+labelErr:
+	snprintf(buf, strlen(error_str), "%s", error_str);
+	return strlen(buf);
+}
+
+/* tsensor driver sysfs store function */
+static ssize_t set_tsensor_param(struct device *dev,
+			struct device_attribute *da,
+			const char *buf, size_t count)
+{
+	int num;
+	struct tegra_tsensor_data *data = dev_get_drvdata(dev);
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	unsigned int reg;
+	unsigned int sft;
+	unsigned int msk;
+	int err;
+	unsigned int counter;
+
+	if (strict_strtoul(buf, 0, (long int *)&num)) {
+		dev_err(dev, "\n file: %s, line=%d return %s() ",
+			__FILE__, __LINE__, __func__);
+		return -EINVAL;
+	}
+
+	counter = tsensor_get_threshold_counter(data, num);
+
+	err = get_param_values(attr->index, &reg, &sft, &msk);
+	if (err < 0)
+		goto labelErr;
+
+	err = tsensor_set_reg_field(data, counter, reg, sft, msk);
+	if (err < 0)
+		goto labelErr;
+
+	/* TH2 clk divide check */
+	if (attr->index == TSENSOR_PARAM_TH2) {
+		msleep(20);
+		(void)cclkg_check_hwdiv2_sensor(data);
+	}
+	return count;
+labelErr:
+	dev_err(dev, "\n file: %s, line=%d, %s(), error=0x%x ", __FILE__,
+		__LINE__, __func__, err);
+	return 0;
+}
+
+static SENSOR_DEVICE_ATTR(tsensor_TH1, S_IRUGO | S_IWUSR,
+		show_tsensor_param, set_tsensor_param, TSENSOR_PARAM_TH1);
+static SENSOR_DEVICE_ATTR(tsensor_TH2, S_IRUGO | S_IWUSR,
+		show_tsensor_param, set_tsensor_param, TSENSOR_PARAM_TH2);
+static SENSOR_DEVICE_ATTR(tsensor_TH3, S_IRUGO | S_IWUSR,
+		show_tsensor_param, set_tsensor_param, TSENSOR_PARAM_TH3);
+static SENSOR_DEVICE_ATTR(tsensor_temperature, S_IRUGO | S_IWUSR,
+		tsensor_show_counters, NULL, TSENSOR_TEMPERATURE);
+
+static struct attribute *tsensor_attributes[] = {
+	&sensor_dev_attr_tsensor_TH1.dev_attr.attr,
+	&sensor_dev_attr_tsensor_TH2.dev_attr.attr,
+	&sensor_dev_attr_tsensor_TH3.dev_attr.attr,
+	&sensor_dev_attr_tsensor_temperature.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group tsensor_attr_group = {
+	.attrs = tsensor_attributes,
+};
+
+/*
+ * returns current state of tsensor
+ * input: tsensor instance
+ *	initializes argument pointer to tsensor_state
+ */
+static void get_ts_state(struct tegra_tsensor_data *data,
+	unsigned char inst, struct tsensor_state *p_state)
+{
+	p_state->prev_state =
+		tsensor_get_reg_field(data,
+		((inst << 16) | SENSOR_STATUS0),
+		STATUS0_PREV_STATE_SHIFT, STATE_MASK);
+	p_state->state =
+		tsensor_get_reg_field(data,
+		((inst << 16) | SENSOR_STATUS0),
+		STATUS0_STATE_SHIFT, STATE_MASK);
+}
+
+/* tsensor driver interrupt handler */
+static irqreturn_t tegra_tsensor_isr(int irq, void *arg_data)
+{
+	struct tegra_tsensor_data *data =
+		(struct tegra_tsensor_data *)arg_data;
+	unsigned long flags;
+	unsigned int val;
+	unsigned int i;
+	struct tsensor_state new_state;
+
+	spin_lock_irqsave(&data->tsensor_lock, flags);
+
+	for (i = 0; i < TSENSOR_COUNT; i++) {
+		val = tsensor_readl(data, ((i << 16) | SENSOR_STATUS0));
+		tsensor_writel(data, val, ((i << 16) | SENSOR_STATUS0));
+		if (val & TSENSOR_SENSOR_X_STATUS0_0_INTR_MASK) {
+			dev_err(data->hwmon_dev, "\n tsensor instance-%d "
+				"interrupt ", i);
+			get_ts_state(data, (unsigned char)i, &new_state);
+			/* counter overflow check */
+			if (new_state.state == TS_OVERFLOW)
+				dev_err(data->hwmon_dev, "\nWarning: "
+					"***** OVERFLOW tsensor ");
+			if (new_state.state != data->ts_state_saved[i]) {
+				dev_err(data->hwmon_dev, "\nTS state "
+					"change: old=%d, new=%d ",
+					data->ts_state_saved[i],
+					new_state.state);
+				data->ts_state_saved[i] = new_state.state;
+			}
+		}
+	}
+
+	spin_unlock_irqrestore(&data->tsensor_lock, flags);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * function to read fuse registers and give - T1, T2, F1 and F2
+ */
+static int read_tsensor_fuse_regs(struct tegra_tsensor_data *data)
+{
+	unsigned int reg1, reg2;
+	int i;
+	unsigned int start, offset1;
+	unsigned int T1, T2;
+
+	/* read tsensor calibration register */
+	/*
+	 * High (~90 DegC) Temperature Calibration value (upper 16 bits of
+	 *          FUSE_TSENSOR_CALIB_0) - F2
+	 * Low (~25 deg C) Temperature Calibration value (lower 16 bits of
+	 *          FUSE_TSENSOR_CALIB_0) - F1
+	 */
+	reg1 = readl(IO_ADDRESS(TEGRA_FUSE_BASE + FUSE_TSENSOR_CALIB_0));
+	fuse_F1 = reg1 & 0xFFFF;
+	fuse_F2 = (reg1 >> 16) & 0xFFFF;
+
+	/*
+	 * FUSE_TJ_ADT_LOWT = T1, FUSE_TJ_ADJ = T2
+	 */
+
+	/*
+	 * Low temp is:
+	 * FUSE_TJ_ADT_LOWT = bits [20:14] or’ed with bits [27:21]
+	 */
+	dev_vdbg(data->hwmon_dev, "\n Tsensor low temp (T1) fuse : ");
+	T1 = 0;
+	start = FUSE_SPARE_BIT_20_0;
+	offset1 = NUM_FUSE_REGS * 4;
+	for (i = 0; i < NUM_FUSE_REGS; i++) {
+		reg1 = readl(IO_ADDRESS((unsigned int)TEGRA_FUSE_BASE +
+			start - (i << 2)));
+		dev_vdbg(data->hwmon_dev, "\n FUSE_SPARE_BIT_%d_0: 0x%x ",
+			(((start - FUSE_SPARE_BIT_0_0) >> 2) - i), reg1);
+		reg2 = readl(IO_ADDRESS((unsigned int)TEGRA_FUSE_BASE +
+			start + offset1 - (i << 2)));
+		dev_vdbg(data->hwmon_dev, "\n FUSE_SPARE_BIT_%d_0: 0x%x ",
+			((((start + offset1) - FUSE_SPARE_BIT_0_0) >> 2)
+			- i), reg2);
+		T1 = (T1 << 1) + ((reg1 | reg2) & 0x1);
+	}
+
+	/*
+	 * High temp is:
+	 * FUSE_TJ_ADJ = bits [6:0] or’ed with bits [13:7]
+	 */
+	dev_vdbg(data->hwmon_dev, "\n Tsensor low temp (T2) fuse : ");
+	start = FUSE_SPARE_BIT_6_0;
+	T2 = 0;
+	for (i = 0; i < NUM_FUSE_REGS; i++) {
+		reg1 = readl(IO_ADDRESS(TEGRA_FUSE_BASE + start -
+			(i << 2)));
+		dev_vdbg(data->hwmon_dev, "\n FUSE_SPARE_BIT_%d_0: 0x%x ",
+			(((start - FUSE_SPARE_BIT_0_0) >> 2) - i), reg1);
+		reg2 = readl(IO_ADDRESS(TEGRA_FUSE_BASE + start + offset1
+			- (i << 2)));
+		dev_vdbg(data->hwmon_dev, "\n FUSE_SPARE_BIT_%d_0: 0x%x ",
+			((((start + offset1) - FUSE_SPARE_BIT_0_0) >> 2)
+			- i), reg2);
+		T2 = (T2 << 1) + ((reg1 | reg2) & 0x1);
+	}
+	pr_info("\n Tsensor fuse calibration F1=%d, F2=%d, T1=%d, T2=%d "
+		, fuse_F1, fuse_F2, T1, T2);
+	fuse_T1 = T1;
+	fuse_T2 = T2;
+	return 0;
+}
+
+/* function to calculate interim temperature */
+static int calc_interim_temp(struct tegra_tsensor_data *data,
+	unsigned int counter, int *p_interim_temp)
+{
+	int val1;
+	/*
+	 * T-int = A * Counter + B
+	 * (Counter is the sensor frequency output)
+	 */
+	if ((fuse_F2 - fuse_F1) <= (fuse_T2 - fuse_T1)) {
+		dev_err(data->hwmon_dev, "\n Error: F2=%d, F1=%d "
+			"difference unexpectedly low. "
+			"Aborting temperature processing ", fuse_F2, fuse_F1);
+		return -EINVAL;
+	} else {
+		/* expression modified after assuming s_A is 10^6 times,
+		 * s_B is 10^2 times and want end result to be 10^2 times
+		 * actual value
+		 */
+		val1 = DIV_ROUND_CLOSEST((A_e_minus6 * counter) , 10000);
+		dev_vdbg(data->hwmon_dev, "\n A*counter / 100 = %d ",
+			val1);
+		*p_interim_temp = (val1 + B_e_minus2);
+	}
+	dev_dbg(data->hwmon_dev, "\n tsensor: counter=0x%x, interim "
+		"temp*100=%d ",
+		counter, *p_interim_temp);
+	return 0;
+}
+
+/*
+ * function to calculate final temperature, given
+ * interim temperature
+ */
+static void calc_final_temp(struct tegra_tsensor_data *data,
+	int interim_temp, int *p_final_temp)
+{
+	int temp1, temp2, temp;
+	/*
+	 * T-final = m * T-int ^2 + n * T-int + p
+	 * m = -0.002775
+	 * n = 1.338811
+	 * p = -7.3
+	 */
+
+	dev_vdbg(data->hwmon_dev, "\n interim_temp=%d ", interim_temp);
+	temp1 = (DIV_ROUND_CLOSEST((interim_temp * interim_temp) , 100));
+	dev_vdbg(data->hwmon_dev, "\n temp1=%d ", temp1);
+	temp1 *= (DIV_ROUND_CLOSEST(m_e_minus6 , 10));
+	dev_vdbg(data->hwmon_dev, "\n m*T-int^2=%d ", temp1);
+	temp1 = (DIV_ROUND_CLOSEST(temp1, 10000));
+	/* we want to keep 3 decimal point digits */
+	dev_vdbg(data->hwmon_dev, "\n m*T-int^2 / 10000=%d ", temp1);
+	dev_dbg(data->hwmon_dev, "\n temp1*100=%d ", temp1);
+
+	temp2 = (DIV_ROUND_CLOSEST(interim_temp * (
+		DIV_ROUND_CLOSEST(n_e_minus6, 100)
+		), 1000)); /* 1000 times actual */
+	dev_vdbg(data->hwmon_dev, "\n n*T-int =%d ", temp2);
+
+	temp = temp1 + temp2;
+	dev_vdbg(data->hwmon_dev, "\n m*T-int^2 + n*T-int =%d ", temp);
+	temp += (p_e_minus2 * 10);
+	temp = DIV_ROUND_CLOSEST(temp, 10);
+	/* final temperature(temp) is 100 times actual value
+	 * to preserve 2 decimal digits and enable fixed point
+	 * computation
+	 */
+	dev_vdbg(data->hwmon_dev, "\n m*T-int^2 + n*T-int + p =%d ",
+		temp);
+	dev_dbg(data->hwmon_dev, "\n Final temp=%d.%d ",
+		get_temperature_int(temp), get_temperature_fraction(temp));
+	*p_final_temp = (int)(temp);
+}
+
+/*
+ * Function to compute constants A and B needed for temperature
+ * calculation
+ * A = (T2-T1) / (F2-F1)
+ * B = T1 – A * F1
+ */
+static int tsensor_get_const_AB(struct tegra_tsensor_data *data)
+{
+	int err;
+
+	/*
+	 *   1. Find fusing registers for 25C (T1, F1) and 90C (T2, F2);
+	 */
+	err = read_tsensor_fuse_regs(data);
+	if (err) {
+		dev_err(data->hwmon_dev, "\n Fuse register read required "
+			"for internal tsensor returns err=%d ", err);
+		return err;
+	}
+
+	if (fuse_F2 != fuse_F1) {
+		if ((fuse_F2 - fuse_F1) <= (fuse_T2 - fuse_T1)) {
+			dev_err(data->hwmon_dev, "\n Error: F2=%d, "
+				"F1=%d, difference"
+				" unexpectedly low. Aborting temperature"
+				"computation ", fuse_F2, fuse_F1);
+			return -EINVAL;
+		} else {
+			A_e_minus6 = ((fuse_T2 - fuse_T1) * 1000000);
+			A_e_minus6 /= (fuse_F2 - fuse_F1);
+			B_e_minus2 = (fuse_T1 * 100) - (
+				DIV_ROUND_CLOSEST((A_e_minus6 *
+				fuse_F1), 10000));
+			/* B is 100 times now */
+		}
+	}
+	dev_dbg(data->hwmon_dev, "\n A_e_minus6 = %d ", A_e_minus6);
+	dev_dbg(data->hwmon_dev, "\n B_e_minus2 = %d ", B_e_minus2);
+	return 0;
+}
+
+/*
+ * function calculates expected temperature corresponding to
+ * given tsensor counter value
+ * Value returned is 100 times calculated temperature since the
+ * calculations are using fixed point arithmetic instead of floating point
+ */
+static int tsensor_count_2_temp(struct tegra_tsensor_data *data,
+	unsigned int count, int *p_temperature)
+{
+	int interim_temp;
+	int err;
+
+	/*
+	 *
+	 * 2. Calculate interim temperature:
+	 */
+	err = calc_interim_temp(data, count, &interim_temp);
+	if (err < 0) {
+		dev_err(data->hwmon_dev, "\n cannot read temperature\n");
+		*p_temperature = -1;
+		return err;
+	}
+
+	/*
+	 *
+	 * 3. Calculate final temperature:
+	 */
+	calc_final_temp(data, interim_temp, p_temperature);
+	return 0;
+}
+
+/*
+ * utility function implements ceil to power of 10 -
+ * e.g. given 987 it returns 1000
+ */
+static int my_ceil_pow10(int num)
+{
+	int tmp;
+	int val = 1;
+	tmp = (num < 0) ? -num : num;
+	if (tmp == 0)
+		return 0;
+	while (tmp > 1) {
+		val *= 10;
+		tmp /= 10;
+	}
+	return val;
+}
+
+/*
+ * function to solve quadratic roots of equation
+ * used to get counter corresponding to given temperature
+ */
+static void get_quadratic_roots(struct tegra_tsensor_data *data,
+		unsigned int temp, unsigned int *p_counter1,
+		unsigned int *p_counter2)
+{
+	/* expr1 = 2 * m * B + n */
+	int expr1_e_minus6;
+	/* expr2 = expr1^2 */
+	int expr2_e_minus6;
+	/* expr3 = m * B^2 + n * B + p */
+	int expr3_e_minus4_1;
+	int expr3_e_minus4_2;
+	int expr3_e_minus4;
+	int expr4_e_minus6;
+	int expr4_e_minus2_1;
+	int expr4_e_minus6_2;
+	int expr4_e_minus6_3;
+	int expr5_e_minus6, expr5_e_minus6_1, expr6, expr7;
+	int expr8_e_minus6, expr9_e_minus6;
+	int multiplier;
+	const int multiplier2 = 1000000;
+	int expr10_e_minus6, expr11_e_minus6;
+	int expr12, expr13;
+
+	dev_vdbg(data->hwmon_dev, "\n A_e_minus6=%d, B_e_minus2=%d, "
+		"m_e_minus6=%d, n_e_minus6=%d, p_e_minus2=%d, "
+		"temp=%d ", A_e_minus6, B_e_minus2, m_e_minus6,
+		n_e_minus6, p_e_minus2, (int)temp);
+	expr1_e_minus6 = (DIV_ROUND_CLOSEST((2 * m_e_minus6 * B_e_minus2),
+		100) + n_e_minus6);
+	dev_vdbg(data->hwmon_dev, "\n 2_m_B_plun_e_minus6=%d ",
+		expr1_e_minus6);
+	expr2_e_minus6 = (DIV_ROUND_CLOSEST(expr1_e_minus6, 1000)) *
+		(DIV_ROUND_CLOSEST(expr1_e_minus6, 1000));
+	dev_vdbg(data->hwmon_dev, "\n expr1^2=%d ", expr2_e_minus6);
+	expr3_e_minus4_1 = (DIV_ROUND_CLOSEST((
+		(DIV_ROUND_CLOSEST((m_e_minus6 * B_e_minus2), 1000)) *
+		(DIV_ROUND_CLOSEST(B_e_minus2, 10))
+		), 100));
+	dev_vdbg(data->hwmon_dev, "\n expr3_e_minus4_1=%d ",
+		expr3_e_minus4_1);
+	expr3_e_minus4_2 = DIV_ROUND_CLOSEST(
+		(DIV_ROUND_CLOSEST(n_e_minus6, 100) * B_e_minus2),
+		100);
+	dev_vdbg(data->hwmon_dev, "\n expr3_e_minus4_2=%d ",
+		expr3_e_minus4_2);
+	expr3_e_minus4 = expr3_e_minus4_1 + expr3_e_minus4_2;
+	dev_vdbg(data->hwmon_dev, "\n expr3=%d ", expr3_e_minus4);
+	expr4_e_minus2_1 = DIV_ROUND_CLOSEST((expr3_e_minus4 +
+		(p_e_minus2 * 1000)), 100);
+	dev_vdbg(data->hwmon_dev, "\n expr4_e_minus2_1=%d ",
+		expr4_e_minus2_1);
+	expr4_e_minus6_2 = (4 * m_e_minus6);
+	dev_vdbg(data->hwmon_dev, "\n expr4_e_minus6_2=%d ",
+		expr4_e_minus6_2);
+	expr4_e_minus6 = DIV_ROUND_CLOSEST((expr4_e_minus2_1 *
+		expr4_e_minus6_2), 100);
+	dev_vdbg(data->hwmon_dev, "\n expr4_minus6=%d ", expr4_e_minus6);
+	expr5_e_minus6_1 = expr2_e_minus6 - expr4_e_minus6;
+	dev_vdbg(data->hwmon_dev, "\n expr5_e_minus6_1=%d ",
+		expr5_e_minus6_1);
+	expr4_e_minus6_3 = (expr4_e_minus6_2 * temp);
+	dev_vdbg(data->hwmon_dev, "\n expr4_e_minus6_3=%d ",
+		expr4_e_minus6_3);
+	expr5_e_minus6 = (expr5_e_minus6_1 + expr4_e_minus6_3);
+	dev_vdbg(data->hwmon_dev, "\n expr5_e_minus6=%d ",
+		expr5_e_minus6);
+	multiplier = my_ceil_pow10(expr5_e_minus6);
+	dev_vdbg(data->hwmon_dev, "\n multiplier=%d ", multiplier);
+	expr6 = int_sqrt(expr5_e_minus6);
+	dev_vdbg(data->hwmon_dev, "\n sqrt top=%d ", expr6);
+	expr7 = int_sqrt(multiplier);
+	dev_vdbg(data->hwmon_dev, "\n sqrt bot=%d ", expr7);
+	if (expr7 == 0) {
+		pr_err("\n Error: %s line=%d, expr7=%d ",
+			__func__, __LINE__, expr7);
+		return;
+	} else {
+		expr8_e_minus6 = (expr6 * multiplier2) / expr7;
+	}
+	dev_vdbg(data->hwmon_dev, "\n sqrt final=%d ", expr8_e_minus6);
+	dev_vdbg(data->hwmon_dev, "\n 2_m_B_plus_n_e_minus6=%d ",
+		expr1_e_minus6);
+	expr9_e_minus6 = DIV_ROUND_CLOSEST((2 * m_e_minus6 * A_e_minus6),
+		1000000);
+	dev_vdbg(data->hwmon_dev, "\n denominator=%d ", expr9_e_minus6);
+	if (expr9_e_minus6 == 0) {
+		pr_err("\n Error: %s line=%d, expr9_e_minus6=%d ",
+			__func__, __LINE__, expr9_e_minus6);
+		return;
+	}
+	expr10_e_minus6 = -expr1_e_minus6 - expr8_e_minus6;
+	dev_vdbg(data->hwmon_dev, "\n expr10_e_minus6=%d ",
+		expr10_e_minus6);
+	expr11_e_minus6 = -expr1_e_minus6 + expr8_e_minus6;
+	dev_vdbg(data->hwmon_dev, "\n expr11_e_minus6=%d ",
+		expr11_e_minus6);
+	expr12 = (expr10_e_minus6 / expr9_e_minus6);
+	dev_vdbg(data->hwmon_dev, "\ncounter1=%d ", expr12);
+	expr13 = (expr11_e_minus6 / expr9_e_minus6);
+	dev_vdbg(data->hwmon_dev, "\ncounter2=%d ", expr13);
+	*p_counter1 = expr12;
+	*p_counter2 = expr13;
+}
+
+/*
+ * function returns tsensor expected counter corresponding to input
+ * temperature in degree Celsius.
+ * e.g. for temperature of 35C, temp=35
+ */
+static void tsensor_temp_2_count(struct tegra_tsensor_data *data,
+				int temp,
+				unsigned int *p_counter1,
+				unsigned int *p_counter2)
+{
+	if (temp > 0) {
+		dev_dbg(data->hwmon_dev, "\n Trying to calculate counter"
+			" for requested temperature"
+			" threshold=%d ", temp);
+		/*
+		 * calculate the constants needed to get roots of
+		 * following quadratic eqn:
+		 * m * A^2 * Counter^2 +
+		 * A * (2 * m * B + n) * Counter +
+		 * (m * B^2 + n * B + p - Temperature) = 0
+		 */
+		get_quadratic_roots(data, temp, p_counter1, p_counter2);
+		/*
+		 * checked at current temperature=35 the counter=11418
+		 * for 50 deg temperature: counter1=22731, counter2=11817
+		 * at 35 deg temperature: counter1=23137, counter2=11411
+		 * hence, for above values we are assuming counter2 has
+		 * the correct value
+		 */
+	} else {
+		if (temp == data->div2_temp) {
+			*p_counter1 = DEFAULT_THRESHOLD_TH2;
+			*p_counter2 = DEFAULT_THRESHOLD_TH2;
+		} else {
+			*p_counter1 = DEFAULT_THRESHOLD_TH3;
+			*p_counter2 = DEFAULT_THRESHOLD_TH3;
+		}
+	}
+}
+
+/*
+ * function to compare computed and expected values with
+ * certain tolerance setting hard coded here
+ */
+static bool cmp_counter(unsigned int actual, unsigned int exp)
+{
+	unsigned int smaller;
+	unsigned int larger;
+	smaller = (actual > exp) ? exp : actual;
+	larger = (smaller == actual) ? exp : actual;
+	if ((larger - smaller) > TSENSOR_COUNTER_TOLERANCE)
+		return false;
+	return true;
+}
+
+/* function to print chart of temperature to counter values */
+static void print_temperature_2_counter_table(
+	struct tegra_tsensor_data *data)
+{
+	int i;
+	/* static list of temperature tested */
+	unsigned int temp_list[] = {
+		30,
+		35,
+		40,
+		45,
+		50,
+		55,
+		60,
+		61,
+		62,
+		63,
+		64,
+		65,
+		70,
+		75,
+		80,
+		85,
+		90,
+		95,
+		100,
+		105,
+		110,
+		115,
+		120
+	};
+	unsigned int counter1, counter2;
+	dev_dbg(data->hwmon_dev, "\n Temperature and counter1 and "
+		"counter2 chart ********** ");
+	for (i = 0; i < ARRAY_SIZE(temp_list); i++) {
+		tsensor_temp_2_count(data, temp_list[i],
+			&counter1, &counter2);
+		dev_dbg(data->hwmon_dev, "\n temperature[%d]=%d, "
+			"counter1=0x%x, counter2=0x%x ",
+			i, temp_list[i], counter1, counter2);
+	}
+	dev_dbg(data->hwmon_dev, "\n\n ");
+}
+
+/*
+ * function to test if conversion of counter to temperature
+ * and vice-versa is working
+ */
+static bool test_temperature_algo(struct tegra_tsensor_data *data)
+{
+	unsigned int actual_counter;
+	unsigned int curr_avg, min_max;
+	unsigned int counter1, counter2;
+	unsigned int T1;
+	int err;
+	bool result1, result2;
+	bool result = false;
+
+	/* read actual counter */
+	err = tsensor_read_counter(data, 0, &curr_avg, &min_max);
+	if (err < 0) {
+		pr_err("\n Error: tsensor0 counter read, err=%d ", err);
+		goto endLabel;
+	}
+	actual_counter = ((curr_avg & 0xFFFF0000) >> 16);
+	dev_dbg(data->hwmon_dev, "\n counter read=0x%x ", actual_counter);
+
+	/* calculate temperature */
+	err = tsensor_count_2_temp(data, actual_counter, &T1);
+	dev_dbg(data->hwmon_dev, "\n %s actual counter=0x%x, calculated "
+		"temperature=%d.%d ", __func__,
+		actual_counter, get_temperature_int(T1),
+		get_temperature_fraction(T1));
+	if (err < 0) {
+		pr_err("\n Error: calculate temperature step ");
+		goto endLabel;
+	}
+
+	/* calculate counter corresponding to read temperature */
+	tsensor_temp_2_count(data, get_temperature_round(T1),
+		&counter1, &counter2);
+	dev_dbg(data->hwmon_dev, "\n given temperature=%d, counter1=0x%x,"
+		" counter2=0x%x ",
+		get_temperature_round(T1), counter1, counter2);
+
+	/* compare counter calculated with actual original counter */
+	result1 = cmp_counter(actual_counter, counter1);
+	result2 = cmp_counter(actual_counter, counter2);
+	if (result1) {
+		dev_dbg(data->hwmon_dev, "\n counter1 matches: actual=%d,"
+			" calc=%d ", actual_counter, counter1);
+		result = true;
+	}
+	if (result2) {
+		dev_dbg(data->hwmon_dev, "\n counter2 matches: actual=%d,"
+			" calc=%d ", actual_counter, counter2);
+		result = true;
+	}
+
+endLabel:
+	return result;
+}
+
+/* tsensor threshold temperature to threshold counter conversion function */
+static unsigned int tsensor_get_threshold_counter(
+	struct tegra_tsensor_data *data,
+	unsigned int temp_threshold)
+{
+	unsigned int counter1, counter2;
+	unsigned int curr_avg, min_max;
+	unsigned int counter;
+	int err;
+
+	tsensor_temp_2_count(data, temp_threshold, &counter1, &counter2);
+	err = tsensor_read_counter(data, 0, &curr_avg, &min_max);
+	if (err < 0) {
+		pr_err("\n Error: tsensor0 counter read, err=%d ", err);
+		return MAX_THRESHOLD;
+	}
+	if (counter2 > ((curr_avg & 0xFFFF0000) >> 16)) {
+		dev_dbg(data->hwmon_dev, "\n choosing counter2=0x%x as "
+			"root ", counter2);
+		counter = counter2;
+	} else {
+		pr_err("\n Error: choosing counter1=0x%x as root, "
+			"counter=0x%x ", counter1,
+			((curr_avg & 0xFFFF0000) >> 16));
+		counter = counter1;
+	}
+	return counter;
+}
+
+/* tsensor temperature threshold setup function */
+static void tsensor_threshold_setup(
+		struct tegra_tsensor_data *data,
+		unsigned char index, bool is_default_threshold)
+{
+	unsigned long config0;
+	unsigned char i = index;
+	unsigned int th2_count = DEFAULT_THRESHOLD_TH2;
+	unsigned int th3_count = DEFAULT_THRESHOLD_TH3;
+	unsigned int th1_count = DEFAULT_THRESHOLD_TH1;
+	unsigned int hysteresis_count;
+	int th0_diff = (DEFAULT_THRESHOLD_TH1 - MIN_THRESHOLD);
+
+	dev_dbg(data->hwmon_dev, "\n started tsensor_threshold_setup %d ",
+		index);
+	config0 = tsensor_readl(data, ((i << 16) | SENSOR_CFG0));
+
+	/* Choose thresholds for sensor0 and sensor1 */
+	/* set to very high values initially - DEFAULT_THRESHOLD */
+	if ((!is_default_threshold) && (i == 0)) {
+		dev_dbg(data->hwmon_dev, "\n before div2 temp_2_count ");
+		th2_count = tsensor_get_threshold_counter(data,
+			data->div2_temp);
+		dev_dbg(data->hwmon_dev, "\n div2_temp=%d, count=%d ",
+			data->div2_temp, th2_count);
+		dev_dbg(data->hwmon_dev, "\n before reset temp_2_count ");
+		th3_count = tsensor_get_threshold_counter(data,
+			data->reset_temp);
+		dev_dbg(data->hwmon_dev, "\n reset_temp=%d, count=%d ",
+			(unsigned int)data->reset_temp, th3_count);
+		dev_dbg(data->hwmon_dev, "\n before sw_intr temp_2_count ");
+		th1_count = tsensor_get_threshold_counter(data,
+			data->sw_intr_temp);
+		dev_dbg(data->hwmon_dev, "\n sw_intr_temp=%d, count=%d ",
+			(unsigned int)data->sw_intr_temp, th1_count);
+		dev_dbg(data->hwmon_dev, "\n before hysteresis temp_2_count ");
+		hysteresis_count = tsensor_get_threshold_counter(data,
+			(data->sw_intr_temp - data->hysteresis));
+		dev_dbg(data->hwmon_dev, "\n hysteresis_temp=%d, count=%d ",
+			(unsigned int)(data->sw_intr_temp - data->hysteresis),
+			hysteresis_count);
+		th0_diff = th1_count - hysteresis_count;
+		dev_dbg(data->hwmon_dev, "\n th0_diff=%d ", th0_diff);
+	}
+	dev_dbg(data->hwmon_dev, "\n before threshold program TH dump: ");
+	dump_threshold(data);
+	dev_dbg(data->hwmon_dev, "\n th3=0x%x, th2=0x%x, th1=0x%x, th0=0x%x ",
+		th3_count, th2_count, th1_count, th0_diff);
+	config0 = (((th2_count & SENSOR_CFG_X_TH_X_MASK)
+		<< SENSOR_CFG1_TH2_SHIFT) |
+		((th1_count & SENSOR_CFG_X_TH_X_MASK) <<
+		SENSOR_CFG1_TH1_SHIFT));
+	tsensor_writel(data, config0, ((i << 16) | SENSOR_CFG1));
+	config0 = (((th0_diff & SENSOR_CFG_X_TH_X_MASK)
+		<< SENSOR_CFG2_TH0_SHIFT) |
+		((th3_count & SENSOR_CFG_X_TH_X_MASK) <<
+		SENSOR_CFG2_TH3_SHIFT));
+	tsensor_writel(data, config0, ((i << 16) | SENSOR_CFG2));
+	dev_dbg(data->hwmon_dev, "\n after threshold program TH dump: ");
+	dump_threshold(data);
+}
+
+/* tsensor config programming function */
+static int tsensor_config_setup(struct tegra_tsensor_data *data)
+{
+	unsigned int config0;
+	unsigned int i;
+	unsigned int status_reg;
+	unsigned int no_resp_count;
+	int err;
+	struct tsensor_state curr_state;
+
+	for (i = 0; i < TSENSOR_COUNT; i++) {
+		/*
+		 * Pre-read setup:
+		 * Set M and N values
+		 * Enable HW features HW_FREQ_DIV_EN, THERMAL_RST_EN
+		 */
+		config0 = tsensor_readl(data, ((i << 16) | SENSOR_CFG0));
+		config0 &= ~((SENSOR_CFG0_M_MASK << SENSOR_CFG0_M_SHIFT) |
+			(SENSOR_CFG0_N_MASK << SENSOR_CFG0_N_SHIFT) |
+			(1 << SENSOR_CFG0_OVERFLOW_INTR) |
+			(1 << SENSOR_CFG0_RST_INTR_SHIFT) |
+			(1 << SENSOR_CFG0_HW_DIV2_INTR_SHIFT) |
+			(1 << SENSOR_CFG0_RST_ENABLE_SHIFT) |
+			(1 << SENSOR_CFG0_HW_DIV2_ENABLE_SHIFT)
+			);
+		/* Set STOP bit */
+		/* Set M and N values */
+		/* Enable HW features HW_FREQ_DIV_EN, THERMAL_RST_EN */
+		config0 |= (((DEFAULT_TSENSOR_M & SENSOR_CFG0_M_MASK) <<
+			SENSOR_CFG0_M_SHIFT) |
+			((DEFAULT_TSENSOR_N & SENSOR_CFG0_N_MASK) <<
+			SENSOR_CFG0_N_SHIFT) |
+			(1 << SENSOR_CFG0_OVERFLOW_INTR) |
+			/*(1 << SENSOR_CFG0_RST_INTR_SHIFT) |
+			(1 << SENSOR_CFG0_HW_DIV2_INTR_SHIFT) |*/
+			(1 << SENSOR_CFG0_STOP_SHIFT) |
+			(1 << SENSOR_CFG0_RST_ENABLE_SHIFT) |
+			(1 << SENSOR_CFG0_HW_DIV2_ENABLE_SHIFT));
+
+		tsensor_writel(data, config0, ((i << 16) | SENSOR_CFG0));
+		tsensor_threshold_setup(data, i, true);
+	}
+
+	for (i = 0; i < TSENSOR_COUNT; i++) {
+		config0 = tsensor_readl(data, ((i << 16) | SENSOR_CFG0));
+		/* Enables interrupts and clears sensor stop */
+		/*
+		 * Interrupts not enabled as software handling is not
+		 * needed in rev1 driver
+		 */
+		/* Disable sensor stop bit */
+		config0 &= ~(1 << SENSOR_CFG0_STOP_SHIFT);
+		tsensor_writel(data, config0, ((i << 16) | SENSOR_CFG0));
+	}
+
+	/* Check if counters are getting updated */
+	no_resp_count = 0;
+
+	for (i = 0; i < TSENSOR_COUNT; i++) {
+		/* if STOP bit is set skip this check */
+		config0 = tsensor_readl(data, ((i << 16) | SENSOR_CFG0));
+		if (!(config0 & (1 << SENSOR_CFG0_STOP_SHIFT))) {
+			unsigned int loop_count = 0;
+			do {
+				status_reg = tsensor_readl(data,
+					(i << 16) | SENSOR_STATUS0);
+				if ((status_reg & (1 <<
+					SENSOR_STATUS_AVG_VALID_SHIFT)) &&
+					(status_reg & (1 <<
+					SENSOR_STATUS_CURR_VALID_SHIFT))) {
+					msleep(1);
+					loop_count++;
+					if (!(loop_count % 200))
+						dev_err(data->hwmon_dev,
+						"\n Warning: Tsensor Counter "
+						"sensor%d not Valid yet. ", i);
+					if (loop_count > MAX_TSENSOR_LOOP1) {
+						no_resp_count++;
+						break;
+					}
+				}
+			} while (!(status_reg &
+				(1 << SENSOR_STATUS_AVG_VALID_SHIFT)) ||
+				(!(status_reg &
+				(1 << SENSOR_STATUS_CURR_VALID_SHIFT))));
+			if (no_resp_count == TSENSOR_COUNT)
+				return -ENODEV;
+		}
+		/* check initial state */
+		get_ts_state(data, (unsigned char)i, &curr_state);
+		data->ts_state_saved[i] = curr_state.state;
+	}
+	/* initialize tsensor chip coefficients */
+	err = get_chip_tsensor_coeff();
+	return err;
+}
+
+/* function to enable tsensor clock */
+static int tsensor_clk_enable(
+	struct tegra_tsensor_data *data,
+	bool enable)
+{
+	int err = 0;
+	unsigned long rate;
+	struct clk *clk_m;
+
+	if (enable) {
+		clk_enable(data->dev_clk);
+		rate = clk_get_rate(data->dev_clk);
+		clk_m = clk_get_sys(NULL, "clk_m");
+		if (clk_get_parent(data->dev_clk) != clk_m) {
+			err = clk_set_parent(data->dev_clk, clk_m);
+			if (err < 0)
+				goto fail;
+		}
+		rate = DEFAULT_TSENSOR_CLK_HZ;
+		if (rate != clk_get_rate(clk_m)) {
+			err = clk_set_rate(data->dev_clk, rate);
+			if (err < 0)
+				goto fail;
+		}
+	} else {
+		clk_disable(data->dev_clk);
+		clk_put(data->dev_clk);
+	}
+fail:
+	return err;
+}
+
+/*
+ * This function enables the tsensor using default configuration
+ * 1. We would need some configuration APIs to calibrate
+ *    the tsensor counters to right temperature
+ * 2. hardware triggered divide cpu clock by 2 as well pmu reset is enabled
+ *    implementation. No software actions are enabled at this point
+ */
+static int tegra_tsensor_setup(struct platform_device *pdev)
+{
+	struct tegra_tsensor_data *data = platform_get_drvdata(pdev);
+	struct resource *r;
+	int err;
+	struct tegra_tsensor_platform_data *tsensor_data;
+
+	data->dev_clk = clk_get(&pdev->dev, NULL);
+	if ((!data->dev_clk) || ((int)data->dev_clk == -(ENOENT))) {
+		dev_err(&pdev->dev, "Couldn't get the clock\n");
+		err = PTR_ERR(data->dev_clk);
+		goto fail;
+	}
+
+	/* Enable tsensor clock */
+	err = tsensor_clk_enable(data, true);
+	if (err < 0)
+		goto err_irq;
+
+	/* Reset tsensor */
+	dev_dbg(&pdev->dev, "\n before tsensor reset %s ", __func__);
+	tegra_periph_reset_assert(data->dev_clk);
+	msleep(1);
+	tegra_periph_reset_deassert(data->dev_clk);
+	msleep(1);
+
+	dev_dbg(&pdev->dev, "\n before tsensor chk pmc reset %s ",
+		__func__);
+	/* Check for previous resets in pmc */
+	if (pmc_check_rst_sensor(data)) {
+		dev_err(data->hwmon_dev, "\n Warning: ***** Last PMC "
+			"Reset source: tsensor detected ");
+	}
+
+	dev_dbg(&pdev->dev, "\n before tsensor pmc reset enable %s ",
+		__func__);
+	/* Enable the sensor reset in PMC */
+	pmc_rst_enable(data, true);
+
+	/* register interrupt */
+	r = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+	if (!r) {
+		dev_err(&pdev->dev, "Failed to get IRQ\n");
+		err = -ENXIO;
+		goto err_irq;
+	}
+	data->irq = r->start;
+	err = request_irq(data->irq, tegra_tsensor_isr,
+			IRQF_DISABLED, pdev->name, data);
+	if (err < 0) {
+		dev_err(&pdev->dev, "Failed to register IRQ\n");
+		goto err_irq;
+	}
+
+	/* tsensor thresholds are read from board/platform specific files */
+	dev_dbg(&pdev->dev, "\n before tsensor get platform data %s ",
+		__func__);
+	tsensor_data = pdev->dev.platform_data;
+	dev_dbg(&pdev->dev, "\n tsensor platform_data=0x%x ",
+		(unsigned int)pdev->dev.platform_data);
+	dev_dbg(&pdev->dev, "\n clk_div temperature=%d ",
+		tsensor_data->hw_clk_div_temperature);
+	data->div2_temp = tsensor_data->hw_clk_div_temperature;
+	dev_dbg(&pdev->dev, "\n reset temperature=%d ",
+		tsensor_data->hw_reset_temperature);
+	data->reset_temp = tsensor_data->hw_reset_temperature;
+	dev_dbg(&pdev->dev, "\n sw_intr temperature=%d ",
+		tsensor_data->sw_intr_temperature);
+	data->sw_intr_temp = tsensor_data->sw_intr_temperature;
+	dev_dbg(&pdev->dev, "\n hysteresis temperature=%d ",
+		tsensor_data->hysteresis);
+	data->hysteresis = tsensor_data->hysteresis;
+
+	dev_dbg(&pdev->dev, "\n before tsensor_config_setup ");
+	if (tsensor_config_setup(data)) {
+		dev_err(&pdev->dev, " [%s,line=%d]: tsensor counters dead! ",
+			__func__, __LINE__);
+		goto err_setup;
+	}
+	dev_dbg(&pdev->dev, "\n before tsensor_get_const_AB ");
+	/* calculate constants needed for temperature conversion */
+	err = tsensor_get_const_AB(data);
+	if (err < 0) {
+		dev_err(&pdev->dev, " Failed to extract temperature "
+			"const\n");
+		goto err_setup;
+	}
+
+	/* test if counter-to-temperature and temperature-to-counter
+	 * are matching */
+	if (!test_temperature_algo(data)) {
+		dev_err(&pdev->dev, " Error: read temperature "
+			"algorithm broken ");
+	}
+
+	print_temperature_2_counter_table(data);
+
+	dev_dbg(&pdev->dev, "\n before tsensor_threshold_setup ");
+	/* change tsensor threshold for instance 0 */
+	tsensor_threshold_setup(data, 0, false);
+	dev_dbg(&pdev->dev, "\n end tsensor_threshold_setup ");
+
+	return 0;
+err_setup:
+	free_irq(data->irq, data);
+err_irq:
+	tsensor_clk_enable(data, false);
+fail:
+	dev_err(&pdev->dev, "\n %s error=%d returned ", __func__, err);
+	return err;
+}
+
+static int __devinit tegra_tsensor_probe(struct platform_device *pdev)
+{
+	struct tegra_tsensor_data *data;
+	struct resource *r;
+	int err;
+
+	data = kzalloc(sizeof(struct tegra_tsensor_data), GFP_KERNEL);
+	if (!data) {
+		dev_err(&pdev->dev, " [%s,line=%d]: Failed to allocate "
+			"memory\n", __func__, __LINE__);
+		err = -ENOMEM;
+		goto exit;
+	}
+	platform_set_drvdata(pdev, data);
+
+	/* Register sysfs hooks */
+	err = sysfs_create_group(&pdev->dev.kobj, &tsensor_attr_group);
+	if (err < 0)
+		goto err0;
+
+	data->hwmon_dev = hwmon_device_register(&pdev->dev);
+	if (IS_ERR(data->hwmon_dev)) {
+		err = PTR_ERR(data->hwmon_dev);
+		goto err0b;
+	}
+
+	dev_set_drvdata(data->hwmon_dev, data);
+
+	spin_lock_init(&data->tsensor_lock);
+
+	/* map tsensor register space */
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (r == NULL) {
+		dev_err(&pdev->dev, " [%s,line=%d]: Failed to get io "
+			"resource\n", __func__, __LINE__);
+		err = -ENODEV;
+		goto err0b;
+	}
+
+	if (!request_mem_region(r->start, (r->end - r->start) + 1,
+				dev_name(&pdev->dev))) {
+		dev_err(&pdev->dev, " [%s,line=%d]: Error mem busy\n",
+			__func__, __LINE__);
+		err = -EBUSY;
+		goto err0b;
+	}
+
+	data->phys = r->start;
+	data->phys_end = r->end;
+	data->base = ioremap(r->start, r->end - r->start + 1);
+	if (!data->base) {
+		dev_err(&pdev->dev, " [%s, line=%d]: can't ioremap "
+			"tsensor iomem\n", __FILE__, __LINE__);
+		err = -ENOMEM;
+		goto err1;
+	}
+
+	/* map pmc rst_status register  */
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	if (r == NULL) {
+		dev_err(&pdev->dev, " [%s,line=%d]: Failed to get io "
+			"resource\n", __func__, __LINE__);
+		err = -ENODEV;
+		goto err2;
+	}
+
+	if (!request_mem_region(r->start, (r->end - r->start) + 1,
+				dev_name(&pdev->dev))) {
+		dev_err(&pdev->dev, " [%s, line=%d]: Error mem busy\n",
+			__func__, __LINE__);
+		err = -EBUSY;
+		goto err2;
+	}
+
+	data->pmc_phys = r->start;
+	data->pmc_phys_end = r->end;
+	data->pmc_rst_base = ioremap(r->start, r->end - r->start + 1);
+	if (!data->pmc_rst_base) {
+		dev_err(&pdev->dev, " [%s, line=%d]: can't ioremap "
+			"pmc iomem\n", __FILE__, __LINE__);
+		err = -ENOMEM;
+		goto err3;
+	}
+
+	/* tegra tsensor - setup and init */
+	if (tegra_tsensor_setup(pdev) != 0)
+		goto err4;
+
+	dev_dbg(&pdev->dev, "\n end tegra_tsensor_probe ");
+	return 0;
+err4:
+	iounmap(data->pmc_rst_base);
+err3:
+	release_mem_region(data->pmc_phys, (data->pmc_phys_end -
+		data->pmc_phys) + 1);
+err2:
+	iounmap(data->base);
+err1:
+	release_mem_region(data->phys, (data->phys_end -
+		data->phys) + 1);
+err0b:
+	sysfs_remove_group(&pdev->dev.kobj, &tsensor_attr_group);
+	hwmon_device_unregister(data->hwmon_dev);
+
+err0:
+	kfree(data);
+exit:
+	dev_err(&pdev->dev, "\n %s error=%d returned ", __func__, err);
+	return err;
+}
+
+static int __devexit tegra_tsensor_remove(struct platform_device *pdev)
+{
+	struct tegra_tsensor_data *data = platform_get_drvdata(pdev);
+
+	hwmon_device_unregister(data->hwmon_dev);
+
+	free_irq(data->irq, data);
+
+	iounmap(data->pmc_rst_base);
+	release_mem_region(data->pmc_phys, (data->pmc_phys_end -
+		data->pmc_phys) + 1);
+	iounmap(data->base);
+	release_mem_region(data->phys, (data->phys_end -
+		data->phys) + 1);
+	sysfs_remove_group(&pdev->dev.kobj, &tsensor_attr_group);
+	platform_set_drvdata(pdev, NULL);
+	kfree(data);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int tsensor_suspend(struct platform_device *pdev,
+	pm_message_t state)
+{
+	struct tegra_tsensor_data *data = platform_get_drvdata(pdev);
+	/* TBD: check anything else that could be needed for suspend */
+	tsensor_clk_enable(data, false);
+
+	return 0;
+}
+
+static int tsensor_resume(struct platform_device *pdev)
+{
+	struct tegra_tsensor_data *data = platform_get_drvdata(pdev);
+	/* TBD: check anything else that could be needed for resume */
+	tsensor_clk_enable(data, true);
+
+	return 0;
+}
+#endif
+
+static struct platform_driver tegra_tsensor_driver = {
+	.driver = {
+		.owner	= THIS_MODULE,
+		.name	= "tegra-tsensor",
+	},
+	.probe		= tegra_tsensor_probe,
+	.remove		= __devexit_p(tegra_tsensor_remove),
+#ifdef CONFIG_PM
+	.suspend	= tsensor_suspend,
+	.resume		= tsensor_resume,
+#endif
+};
+
+static int __init tegra_tsensor_init(void)
+{
+	init_flag = 0;
+	if (platform_driver_register(&tegra_tsensor_driver))
+		goto exit;
+	init_flag = 1;
+	return 0;
+
+exit:
+	return -ENODEV;
+}
+
+static void __exit tegra_tsensor_exit(void)
+{
+	if (init_flag) {
+		platform_driver_unregister(&tegra_tsensor_driver);
+		init_flag = 0;
+	}
+}
+
+MODULE_AUTHOR("nvidia");
+MODULE_DESCRIPTION("Nvidia Tegra Temperature Sensor driver");
+MODULE_LICENSE("GPL");
+
+module_init(tegra_tsensor_init);
+module_exit(tegra_tsensor_exit);
+