[U-Boot] [PATCH v6 2/4] mx6: thermal: Add i.MX6 CPU thermal sensor support

nitin.garg at freescale.com nitin.garg at freescale.com
Fri Nov 14 21:13:04 CET 2014


From: Nitin Garg <nitin.garg at freescale.com>

i.MX6 SoC has onchip temperature sensor. Add driver
for this sensor.

Signed-off-by: Nitin Garg <nitin.garg at freescale.com>
---
 drivers/Makefile              |    1 +
 drivers/thermal/Makefile      |    8 +++
 drivers/thermal/imx_thermal.c |  144 +++++++++++++++++++++++++++++++++++++++++
 include/imx_thermal.h         |   15 +++++
 4 files changed, 168 insertions(+)
 create mode 100644 drivers/thermal/Makefile
 create mode 100644 drivers/thermal/imx_thermal.c
 create mode 100644 include/imx_thermal.h

diff --git a/drivers/Makefile b/drivers/Makefile
index 33227c8..7683c61 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -21,3 +21,4 @@ obj-y += pwm/
 obj-y += input/
 # SOC specific infrastructure drivers.
 obj-y += soc/
+obj-y += thermal/
diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
new file mode 100644
index 0000000..04ae395
--- /dev/null
+++ b/drivers/thermal/Makefile
@@ -0,0 +1,8 @@
+#
+# (C) Copyright 2014 Freescale Semiconductor, Inc.
+# Author: Nitin Garg <nitin.garg at freescale.com>
+#
+# SPDX-License-Identifier:	GPL-2.0+
+#
+
+obj-$(CONFIG_IMX6_THERMAL) += imx_thermal.o
diff --git a/drivers/thermal/imx_thermal.c b/drivers/thermal/imx_thermal.c
new file mode 100644
index 0000000..fe9dd85
--- /dev/null
+++ b/drivers/thermal/imx_thermal.c
@@ -0,0 +1,144 @@
+/*
+ * (C) Copyright 2014 Freescale Semiconductor, Inc.
+ * Author: Nitin Garg <nitin.garg at freescale.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <config.h>
+#include <common.h>
+#include <div64.h>
+#include <fuse.h>
+#include <asm/io.h>
+#include <asm/arch/clock.h>
+
+#define TEMPERATURE_MIN		-40
+#define TEMPERATURE_HOT		80
+#define TEMPERATURE_MAX		125
+#define FACTOR0			10000000
+#define FACTOR1			15976
+#define FACTOR2			4297157
+#define MEASURE_FREQ		327
+
+#define TEMPSENSE0_TEMP_CNT_SHIFT	8
+#define TEMPSENSE0_TEMP_CNT_MASK	(0xfff << TEMPSENSE0_TEMP_CNT_SHIFT)
+#define TEMPSENSE0_FINISHED		(1 << 2)
+#define TEMPSENSE0_MEASURE_TEMP		(1 << 1)
+#define TEMPSENSE0_POWER_DOWN		(1 << 0)
+#define MISC0_REFTOP_SELBIASOFF		(1 << 3)
+#define TEMPSENSE1_MEASURE_FREQ		0xffff
+
+static int read_cpu_temperature(u32 fuse)
+{
+	int temperature;
+	unsigned int reg, n_meas;
+	struct anatop_regs *anatop = (struct anatop_regs *)ANATOP_BASE_ADDR;
+	int t1, n1;
+	u32 c1, c2;
+	u64 temp64;
+
+	/* make sure pll3 is enabled for thermal sensor */
+	enable_pll3();
+
+	/*
+	 * Sensor data layout:
+	 *   [31:20] - sensor value @ 25C
+	 * We use universal formula now and only need sensor value @ 25C
+	 * slope = 0.4297157 - (0.0015976 * 25C fuse)
+	 */
+	n1 = fuse >> 20;
+	t1 = 25; /* t1 always 25C */
+
+	/*
+	 * Derived from linear interpolation:
+	 * slope = 0.4297157 - (0.0015976 * 25C fuse)
+	 * slope = (FACTOR2 - FACTOR1 * n1) / FACTOR0
+	 * (Nmeas - n1) / (Tmeas - t1) = slope
+	 * We want to reduce this down to the minimum computation necessary
+	 * for each temperature read.  Also, we want Tmeas in millicelsius
+	 * and we don't want to lose precision from integer division. So...
+	 * Tmeas = (Nmeas - n1) / slope + t1
+	 * milli_Tmeas = 1000 * (Nmeas - n1) / slope + 1000 * t1
+	 * milli_Tmeas = -1000 * (n1 - Nmeas) / slope + 1000 * t1
+	 * Let constant c1 = (-1000 / slope)
+	 * milli_Tmeas = (n1 - Nmeas) * c1 + 1000 * t1
+	 * Let constant c2 = n1 *c1 + 1000 * t1
+	 * milli_Tmeas = c2 - Nmeas * c1
+	 */
+	temp64 = FACTOR0;
+	temp64 *= 1000;
+	do_div(temp64, FACTOR1 * n1 - FACTOR2);
+	c1 = temp64;
+	c2 = n1 * c1 + 1000 * t1;
+
+	/*
+	 * now we only use single measure, every time we read
+	 * the temperature, we will power on/down anadig thermal
+	 * module
+	 */
+	writel(TEMPSENSE0_POWER_DOWN, &anatop->tempsense0_clr);
+	writel(MISC0_REFTOP_SELBIASOFF, &anatop->ana_misc0_set);
+
+	/* setup measure freq */
+	reg = readl(&anatop->tempsense1);
+	reg &= ~TEMPSENSE1_MEASURE_FREQ;
+	reg |= MEASURE_FREQ;
+	writel(reg, &anatop->tempsense1);
+
+	/* start the measurement process */
+	writel(TEMPSENSE0_MEASURE_TEMP, &anatop->tempsense0_clr);
+	writel(TEMPSENSE0_FINISHED, &anatop->tempsense0_clr);
+	writel(TEMPSENSE0_MEASURE_TEMP, &anatop->tempsense0_set);
+
+	/* make sure that the latest temp is valid */
+	while ((readl(&anatop->tempsense0) &
+		TEMPSENSE0_FINISHED) == 0)
+		udelay(10000);
+
+	/* read temperature count */
+	reg = readl(&anatop->tempsense0);
+	n_meas = (reg & TEMPSENSE0_TEMP_CNT_MASK)
+		>> TEMPSENSE0_TEMP_CNT_SHIFT;
+	writel(TEMPSENSE0_FINISHED, &anatop->tempsense0_clr);
+
+	/* milli_Tmeas = c2 - Nmeas * c1 */
+	temperature = (c2 - n_meas * c1)/1000;
+
+	/* power down anatop thermal sensor */
+	writel(TEMPSENSE0_POWER_DOWN, &anatop->tempsense0_set);
+	writel(MISC0_REFTOP_SELBIASOFF, &anatop->ana_misc0_clr);
+
+	return temperature;
+}
+
+void check_cpu_temperature(void)
+{
+	int cpu_tmp = 0;
+	u32 fuse = ~0;
+
+	/* Read Temperature calibration data fuse */
+	fuse_read(1, 6, &fuse);
+
+	/* Check for valid fuse */
+	if (fuse == 0 || fuse == ~0) {
+		printf("CPU:   Temperature: invalid data, fuse: 0x%x\n", fuse);
+		return;
+	}
+
+	cpu_tmp = read_cpu_temperature(fuse);
+	while (cpu_tmp > TEMPERATURE_MIN && cpu_tmp < TEMPERATURE_MAX) {
+		if (cpu_tmp >= TEMPERATURE_HOT) {
+			printf("CPU is %d C, too hot to boot, waiting...\n",
+			       cpu_tmp);
+			udelay(5000000);
+			cpu_tmp = read_cpu_temperature(fuse);
+		} else {
+			break;
+		}
+	}
+
+	if (cpu_tmp > TEMPERATURE_MIN && cpu_tmp < TEMPERATURE_MAX)
+		printf("CPU:   Temperature %d C\n", cpu_tmp);
+	else
+		printf("CPU:   Temperature: invalid sensor data\n");
+}
diff --git a/include/imx_thermal.h b/include/imx_thermal.h
new file mode 100644
index 0000000..979664a
--- /dev/null
+++ b/include/imx_thermal.h
@@ -0,0 +1,15 @@
+/*
+ * IMX Thermal Defines
+ *-------------------------------------------------------------------
+ *
+ * Copyright 2014 Freescale Semiconductor, Inc
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef __IMX6_THERMAL_H__
+#define	__IMX6_THERMAL_H__
+
+void check_cpu_temperature(void);
+
+#endif /* __IMX6_THERMAL_H__ */
-- 
1.7.9.5



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