thermal: qcom: tsens: Add a skeletal TSENS drivers

TSENS is Qualcomms' thermal temperature sensor device. It
supports reading temperatures from multiple thermal sensors
present on various QCOM SoCs.
Calibration data is generally read from a non-volatile memory
(eeprom) device.

Add a skeleton driver with all the necessary abstractions so
a variety of qcom device families which support TSENS can
add driver extensions.

Also add the required device tree bindings which can be used
to describe the TSENS device in DT.

Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
Reviewed-by: Lina Iyer <lina.iyer@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

1 files changed, 141 insertions, 0 deletions

diff --git a/drivers/thermal/qcom/tsens-common.c b/drivers/thermal/qcom/tsens-common.c
new file mode 100644
index 000000000000..4a1af151bd53
--- /dev/null
+++ b/drivers/thermal/qcom/tsens-common.c
@@ -0,0 +1,141 @@
+/*
+ * 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.
+ *
+ */
+
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include "tsens.h"
+
+#define S0_ST_ADDR		0x1030
+#define SN_ADDR_OFFSET		0x4
+#define SN_ST_TEMP_MASK		0x3ff
+#define CAL_DEGC_PT1		30
+#define CAL_DEGC_PT2		120
+#define SLOPE_FACTOR		1000
+#define SLOPE_DEFAULT		3200
+
+char *qfprom_read(struct device *dev, const char *cname)
+{
+	struct nvmem_cell *cell;
+	ssize_t data;
+	char *ret;
+
+	cell = nvmem_cell_get(dev, cname);
+	if (IS_ERR(cell))
+		return ERR_CAST(cell);
+
+	ret = nvmem_cell_read(cell, &data);
+	nvmem_cell_put(cell);
+
+	return ret;
+}
+
+/*
+ * Use this function on devices where slope and offset calculations
+ * depend on calibration data read from qfprom. On others the slope
+ * and offset values are derived from tz->tzp->slope and tz->tzp->offset
+ * resp.
+ */
+void compute_intercept_slope(struct tsens_device *tmdev, u32 *p1,
+			     u32 *p2, u32 mode)
+{
+	int i;
+	int num, den;
+
+	for (i = 0; i < tmdev->num_sensors; i++) {
+		dev_dbg(tmdev->dev,
+			"sensor%d - data_point1:%#x data_point2:%#x\n",
+			i, p1[i], p2[i]);
+
+		tmdev->sensor[i].slope = SLOPE_DEFAULT;
+		if (mode == TWO_PT_CALIB) {
+			/*
+			 * slope (m) = adc_code2 - adc_code1 (y2 - y1)/
+			 *	temp_120_degc - temp_30_degc (x2 - x1)
+			 */
+			num = p2[i] - p1[i];
+			num *= SLOPE_FACTOR;
+			den = CAL_DEGC_PT2 - CAL_DEGC_PT1;
+			tmdev->sensor[i].slope = num / den;
+		}
+
+		tmdev->sensor[i].offset = (p1[i] * SLOPE_FACTOR) -
+				(CAL_DEGC_PT1 *
+				tmdev->sensor[i].slope);
+		dev_dbg(tmdev->dev, "offset:%d\n", tmdev->sensor[i].offset);
+	}
+}
+
+static inline int code_to_degc(u32 adc_code, const struct tsens_sensor *s)
+{
+	int degc, num, den;
+
+	num = (adc_code * SLOPE_FACTOR) - s->offset;
+	den = s->slope;
+
+	if (num > 0)
+		degc = num + (den / 2);
+	else if (num < 0)
+		degc = num - (den / 2);
+	else
+		degc = num;
+
+	degc /= den;
+
+	return degc;
+}
+
+int get_temp_common(struct tsens_device *tmdev, int id, int *temp)
+{
+	struct tsens_sensor *s = &tmdev->sensor[id];
+	u32 code;
+	unsigned int sensor_addr;
+	int last_temp = 0, ret;
+
+	sensor_addr = S0_ST_ADDR + s->hw_id * SN_ADDR_OFFSET;
+	ret = regmap_read(tmdev->map, sensor_addr, &code);
+	if (ret)
+		return ret;
+	last_temp = code & SN_ST_TEMP_MASK;
+
+	*temp = code_to_degc(last_temp, s) * 1000;
+
+	return 0;
+}
+
+static const struct regmap_config tsens_config = {
+	.reg_bits	= 32,
+	.val_bits	= 32,
+	.reg_stride	= 4,
+};
+
+int __init init_common(struct tsens_device *tmdev)
+{
+	void __iomem *base;
+
+	base = of_iomap(tmdev->dev->of_node, 0);
+	if (IS_ERR(base))
+		return -EINVAL;
+
+	tmdev->map = devm_regmap_init_mmio(tmdev->dev, base, &tsens_config);
+	if (!tmdev->map) {
+		iounmap(base);
+		return -ENODEV;
+	}
+
+	return 0;
+}