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lantiq: fix thermal sensors driver

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Read the temperature including the decimale place from the CGU_GPHY1_CR
register.

Decrement the temperature read from the register by 38.0 degree celsius.
The temperature range of the sensor is -38.0 to +154 °C and the register
value 0 is equal to -38.0 °C. This fixes the report of unrealistic
temperatures as seen on all tested boards.

Give the SoC a few milliseconds to get the first temperature value. On
some rare occasions there is no temperature value in the register when
read the first time after activation. This leads to a reported
temperature of -38.0 °C on boot.

Only version 1.2 of the vr9 SoC has a temperature sensor. Add a check
to make sure the driver doesn't load on v1.1 vr9 SoCs.

Signed-off-by: Mathias Kresin <dev@kresin.me>
This commit is contained in:
Mathias Kresin 2016-10-17 20:25:53 +02:00
parent eba84bee4c
commit 23e3314cad
1 changed files with 21 additions and 5 deletions
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26
target/linux/lantiq/patches-4.4/0302-xrx200-add-sensors-driver.patch
View file

@ -27,7 +27,7 @@
depends on SPI_MASTER
--- /dev/null
+++ b/drivers/hwmon/ltq-cputemp.c
@@ -0,0 +1,138 @@
@@ -0,0 +1,154 @@
+/* Lantiq CPU Temperatur sensor driver for xrx200
+ *
+ * Copyright (C) 2016 Florian Eckert <feckert@tdt.de>
@ -48,6 +48,7 @@
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/of_device.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
@ -61,6 +62,9 @@
+static void ltq_cputemp_enable(void)
+{
+ ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) | CGU_TEMP_PD, CGU_GPHY1_CR);
+
+ /* wait a short moment to let the SoC get the first temperatur value */
+ mdelay(100);
+}
+
+static void ltq_cputemp_disable(void)
@ -70,8 +74,16 @@
+
+static int ltq_cputemp_read(void)
+{
+ /* Shift 9 for register alignment and 1 to divide value by 2 */
+ return (ltq_cgu_r32(CGU_GPHY1_CR) >> 10) & 0xFF;
+ int value;
+
+ /* get the temperature including one decimal place */
+ value = (ltq_cgu_r32(CGU_GPHY1_CR) >> 9) & 0x01FF;
+ value = (value << 2 ) + value;
+
+ /* range -38 to +154 °C, register value zero is -38.0 °C */
+ value -= 380;
+
+ return value;
+}
+
+static ssize_t show_cputemp(struct device *dev,
@ -81,7 +93,7 @@
+
+ value = ltq_cputemp_read();
+ /* scale temp to millidegree */
+ value = value * 1000;
+ value = value * 100;
+
+ return sprintf(buf, "%d\n", value);
+}
@ -101,6 +113,10 @@
+ int ret;
+ struct device *hwmon_dev;
+
+ /* available on vr9 v1.2 SoCs only */
+ if (ltq_soc_type() != SOC_TYPE_VR9_2)
+ return -ENODEV;
+
+ hwmon_dev = devm_hwmon_device_register_with_groups(&pdev->dev,
+ "CPU0",
+ NULL,
@ -114,7 +130,7 @@
+
+ ltq_cputemp_enable();
+ value = ltq_cputemp_read();
+ dev_info(&pdev->dev, "Current CPU die temperature: %d °C", value);
+ dev_info(&pdev->dev, "Current CPU die temperature: %d.%d °C", value / 10, value % 10);
+
+ return 0;
+