[U-Boot] [PATCH v4 3/5] mx6: thermal: Add i.MX6 CPU thermal sensor support
Nitin Garg
nitin.garg at freescale.com
Tue Sep 16 18:48:56 CEST 2014
i.MX6 SoC has onchip temperature sensor. Add driver
for this sensor.
Signed-off-by: Nitin Garg <nitin.garg at freescale.com>
---
Changes in v4: None
Changes in v3: None
Changes in v2: None
drivers/Makefile | 1 +
drivers/thermal/Makefile | 8 +++
drivers/thermal/imx_thermal.c | 137 +++++++++++++++++++++++++++++++++++++++++
include/imx_thermal.h | 15 +++++
4 files changed, 161 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 b22b109..fc57e49 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -16,3 +16,4 @@ obj-y += watchdog/
obj-$(CONFIG_QE) += qe/
obj-y += memory/
obj-y += pwm/
+obj-y += thermal/
diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
new file mode 100644
index 0000000..04ae395
--- /dev/null
+++ b/drivers/thermal/Makefile
@@ -0,0 +1,8 @@
+#
+# (C) Copyright 2014 Freescale Semiconductor, Inc.
+# Author: Nitin Garg <nitin.garg at freescale.com>
+#
+# SPDX-License-Identifier: GPL-2.0+
+#
+
+obj-$(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..3b53b61
--- /dev/null
+++ b/drivers/thermal/imx_thermal.c
@@ -0,0 +1,137 @@
+/*
+ * (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/crm_regs.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
+
+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(BM_ANADIG_TEMPSENSE0_POWER_DOWN, &anatop->tempsense0_clr);
+ writel(BM_ANADIG_ANA_MISC0_REFTOP_SELBIASOFF, &anatop->ana_misc0_set);
+
+ /* setup measure freq */
+ reg = readl(&anatop->tempsense1);
+ reg &= ~BM_ANADIG_TEMPSENSE1_MEASURE_FREQ;
+ reg |= MEASURE_FREQ;
+ writel(reg, &anatop->tempsense1);
+
+ /* start the measurement process */
+ writel(BM_ANADIG_TEMPSENSE0_MEASURE_TEMP, &anatop->tempsense0_clr);
+ writel(BM_ANADIG_TEMPSENSE0_FINISHED, &anatop->tempsense0_clr);
+ writel(BM_ANADIG_TEMPSENSE0_MEASURE_TEMP, &anatop->tempsense0_set);
+
+ /* make sure that the latest temp is valid */
+ while ((readl(&anatop->tempsense0) &
+ BM_ANADIG_TEMPSENSE0_FINISHED) == 0)
+ udelay(10000);
+
+ /* read temperature count */
+ reg = readl(&anatop->tempsense0);
+ n_meas = (reg & BM_ANADIG_TEMPSENSE0_TEMP_VALUE)
+ >> BP_ANADIG_TEMPSENSE0_TEMP_VALUE;
+ writel(BM_ANADIG_TEMPSENSE0_FINISHED, &anatop->tempsense0_clr);
+
+ /* milli_Tmeas = c2 - Nmeas * c1 */
+ temperature = (c2 - n_meas * c1)/1000;
+
+ /* power down anatop thermal sensor */
+ writel(BM_ANADIG_TEMPSENSE0_POWER_DOWN, &anatop->tempsense0_set);
+ writel(BM_ANADIG_ANA_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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