thermal: qcom: tsens-8996: Add support for 8996 family of SoCs

The TSENS controller in 8996 family of SoCs is capable of converting the
ADC code outputs to real temperature values (in decidegree Celsius).
It can also be programmed to provide raw ADC code, but the secure software
on 8996 programs it to provide real temperatures and also does the needed
calibrations.

We check the valid bit to ensure valid data is read by the AHB master.
And the spec recommends the below algorithm to read data 3 consecutive
times, which takes care of the worst case delay taken to propagate the
updated data to the register.

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

1 files changed, 84 insertions, 0 deletions

diff --git a/drivers/thermal/qcom/tsens-8996.c b/drivers/thermal/qcom/tsens-8996.c
new file mode 100644
index 000000000000..e2e12745ad21
--- /dev/null
+++ b/drivers/thermal/qcom/tsens-8996.c
@@ -0,0 +1,84 @@
+/*
+ * 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/platform_device.h>
+#include <linux/regmap.h>
+#include "tsens.h"
+
+#define STATUS_OFFSET	0x10a0
+#define LAST_TEMP_MASK	0xfff
+#define STATUS_VALID_BIT	BIT(21)
+#define CODE_SIGN_BIT		BIT(11)
+
+static int get_temp_8996(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, last_temp2 = 0, last_temp3 = 0, ret;
+
+	sensor_addr = STATUS_OFFSET + s->hw_id * 4;
+	ret = regmap_read(tmdev->map, sensor_addr, &code);
+	if (ret)
+		return ret;
+	last_temp = code & LAST_TEMP_MASK;
+	if (code & STATUS_VALID_BIT)
+		goto done;
+
+	/* Try a second time */
+	ret = regmap_read(tmdev->map, sensor_addr, &code);
+	if (ret)
+		return ret;
+	if (code & STATUS_VALID_BIT) {
+		last_temp = code & LAST_TEMP_MASK;
+		goto done;
+	} else {
+		last_temp2 = code & LAST_TEMP_MASK;
+	}
+
+	/* Try a third/last time */
+	ret = regmap_read(tmdev->map, sensor_addr, &code);
+	if (ret)
+		return ret;
+	if (code & STATUS_VALID_BIT) {
+		last_temp = code & LAST_TEMP_MASK;
+		goto done;
+	} else {
+		last_temp3 = code & LAST_TEMP_MASK;
+	}
+
+	if (last_temp == last_temp2)
+		last_temp = last_temp2;
+	else if (last_temp2 == last_temp3)
+		last_temp = last_temp3;
+done:
+	/* Code sign bit is the sign extension for a negative value */
+	if (last_temp & CODE_SIGN_BIT)
+		last_temp |= ~CODE_SIGN_BIT;
+
+	/* Temperatures are in deciCelicius */
+	*temp = last_temp * 100;
+
+	return 0;
+}
+
+const struct tsens_ops ops_8996 = {
+	.init		= init_common,
+	.get_temp	= get_temp_8996,
+};
+
+const struct tsens_data data_8996 = {
+	.num_sensors	= 13,
+	.ops		= &ops_8996,
+};