[PATCH v2 1/2] hwmon: (ltq-cputemp) add cpu temp sensor driver

From: Florian Eckert
Date: Mon Aug 21 2017 - 08:41:38 EST

Add the lantiq cpu temperature sensor support for xrx200.

Signed-off-by: Florian Eckert <fe@xxxxxxxxxx>
---
v2:
- remove default in Makefile
- fix spelling
- removing first read delay, because temperature value is not read during boot
anymore
- change calculation, compiler should to the optimization
- remove unnecessary initialization
- use new devm_hwmon_device_register_with_info API
- use module_platform_driver function

The soc detection for lantiq is done with this pattern. If it sould be more
generic we should change this global.

drivers/hwmon/Kconfig | 7 ++
drivers/hwmon/Makefile | 1 +
drivers/hwmon/ltq-cputemp.c | 175 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 183 insertions(+)
create mode 100644 drivers/hwmon/ltq-cputemp.c

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 5ef2814345ef..218332f0e913 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -790,6 +790,13 @@ config SENSORS_LTC4261
This driver can also be built as a module. If so, the module will
be called ltc4261.

+config SENSORS_LTQ_CPUTEMP
+ bool "Lantiq cpu temperature sensor driver"
+ depends on LANTIQ
+ help
+ If you say yes here you get support for the temperature
+ sensor inside your CPU.
+
config SENSORS_MAX1111
tristate "Maxim MAX1111 Serial 8-bit ADC chip and compatibles"
depends on SPI_MASTER
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index d4641a9f16c1..c84d9784be98 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -110,6 +110,7 @@ obj-$(CONFIG_SENSORS_LTC4222) += ltc4222.o
obj-$(CONFIG_SENSORS_LTC4245) += ltc4245.o
obj-$(CONFIG_SENSORS_LTC4260) += ltc4260.o
obj-$(CONFIG_SENSORS_LTC4261) += ltc4261.o
+obj-$(CONFIG_SENSORS_LTQ_CPUTEMP) += ltq-cputemp.o
obj-$(CONFIG_SENSORS_MAX1111) += max1111.o
obj-$(CONFIG_SENSORS_MAX16065) += max16065.o
obj-$(CONFIG_SENSORS_MAX1619) += max1619.o
diff --git a/drivers/hwmon/ltq-cputemp.c b/drivers/hwmon/ltq-cputemp.c
new file mode 100644
index 000000000000..21c77a125c27
--- /dev/null
+++ b/drivers/hwmon/ltq-cputemp.c
@@ -0,0 +1,175 @@
+/* Lantiq cpu temperature sensor driver
+ *
+ * Copyright (C) 2017 Florian Eckert <fe@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version
+ *
+ * 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
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>
+ */
+
+#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>
+
+#include <lantiq_soc.h>
+
+/* gphy1 configuration register contains cpu temperature */
+#define CGU_GPHY1_CR 0x0040
+#define CGU_TEMP_PD BIT(19)
+
+static void ltq_cputemp_enable(void)
+{
+ ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) | CGU_TEMP_PD, CGU_GPHY1_CR);
+}
+
+static void ltq_cputemp_disable(void)
+{
+ ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) & ~CGU_TEMP_PD, CGU_GPHY1_CR);
+}
+
+static int ltq_read(struct device *dev, enum hwmon_sensor_types type,
+ u32 attr, int channel, long *temp)
+{
+ int value;
+
+ switch (attr) {
+ case hwmon_temp_input:
+ /* get the temperature including one decimal place */
+ value = (ltq_cgu_r32(CGU_GPHY1_CR) >> 9) & 0x01FF;
+ value = value * 5;
+ /* range -38 to +154 ÂC, register value zero is -38.0 ÂC */
+ value -= 380;
+ /* scale temp to millidegree */
+ value = value * 100;
+ break;
+ default:
+ return -EOPNOTSUPP;
+ }
+
+ *temp = value;
+ return 0;
+}
+
+
+static umode_t ltq_is_visible(const void *_data, enum hwmon_sensor_types type,
+ u32 attr, int channel)
+{
+ if (type != hwmon_temp)
+ return 0;
+
+ switch (attr) {
+ case hwmon_temp_input:
+ return S_IRUGO;
+ default:
+ return 0;
+ }
+}
+
+static const u32 ltq_chip_config[] = {
+ HWMON_C_REGISTER_TZ,
+ 0
+};
+
+static const struct hwmon_channel_info ltq_chip = {
+ .type = hwmon_chip,
+ .config = ltq_chip_config,
+};
+
+static const u32 ltq_temp_config[] = {
+ HWMON_T_INPUT,
+ 0
+};
+
+static const struct hwmon_channel_info ltq_temp = {
+ .type = hwmon_temp,
+ .config = ltq_temp_config,
+};
+
+static const struct hwmon_channel_info *ltq_info[] = {
+ &ltq_chip,
+ &ltq_temp,
+ NULL
+};
+
+static const struct hwmon_ops ltq_hwmon_ops = {
+ .is_visible = ltq_is_visible,
+ .read = ltq_read,
+};
+
+static const struct hwmon_chip_info ltq_chip_info = {
+ .ops = &ltq_hwmon_ops,
+ .info = ltq_info,
+};
+
+static int ltq_cputemp_probe(struct platform_device *pdev)
+{
+ 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_info(&pdev->dev,
+ "CPU0",
+ NULL,
+ &ltq_chip_info,
+ NULL);
+
+ if (IS_ERR(hwmon_dev)) {
+ dev_err(&pdev->dev, "Failed to register as hwmon device");
+ return PTR_ERR(hwmon_dev);
+ }
+
+ ltq_cputemp_enable();
+
+ return 0;
+}
+
+static int ltq_cputemp_release(struct platform_device *pdev)
+{
+ ltq_cputemp_disable();
+ return 0;
+}
+
+const struct of_device_id ltq_cputemp_match[] = {
+ { .compatible = "lantiq,cputemp" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, ltq_cputemp_match);
+
+static struct platform_driver ltq_cputemp_driver = {
+ .probe = ltq_cputemp_probe,
+ .remove = ltq_cputemp_release,
+ .driver = {
+ .name = "ltq-cputemp",
+ .of_match_table = ltq_cputemp_match,
+ },
+};
+
+int __init init_ltq_cputemp(void)
+{
+ return platform_driver_register(&ltq_cputemp_driver);
+}
+
+void clean_ltq_cputemp(void)
+{
+ platform_driver_unregister(&ltq_cputemp_driver);
+}
+
+module_platform_driver(ltq_cputemp_driver);
+
+MODULE_AUTHOR("Florian Eckert <fe@xxxxxxxxxx>");
+MODULE_DESCRIPTION("Lantiq cpu temperature sensor driver");
+MODULE_LICENSE("GPL");
--
2.11.0