hwmon: (ltq-cputemp) add cpu temp sensor driver

Add the lantiq cpu temperature sensor support for xrx200.

Signed-off-by: Florian Eckert <fe@dev.tdt.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

3 files changed, 171 insertions, 0 deletions

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 5b9a61f766ac..d65431417b17 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -791,6 +791,13 @@ 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..1d33f94594c1
--- /dev/null
+++ b/drivers/hwmon/ltq-cputemp.c
@@ -0,0 +1,163 @@
+/* Lantiq cpu temperature sensor driver
+ *
+ * Copyright (C) 2017 Florian Eckert <fe@dev.tdt.de>
+ *
+ * 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/bitops.h>
+#include <linux/delay.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/of_device.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 *data)
+{
+        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 °C, register value zero is -38.0 °C */
+                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 0444;
+        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;
+        int err = 0;
+
+        /* available on vr9 v1.2 SoCs only */
+        if (ltq_soc_type() != SOC_TYPE_VR9_2)
+                return -ENODEV;
+
+        err = devm_add_action(&pdev->dev, ltq_cputemp_disable, NULL);
+        if (err)
+                return err;
+
+        ltq_cputemp_enable();
+
+        hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
+                                                         "ltq_cputemp",
+                                                         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);
+        }
+
+        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,
+        .driver = {
+                .name = "ltq-cputemp",
+                .of_match_table = ltq_cputemp_match,
+        },
+};
+
+module_platform_driver(ltq_cputemp_driver);
+
+MODULE_AUTHOR("Florian Eckert <fe@dev.tdt.de>");
+MODULE_DESCRIPTION("Lantiq cpu temperature sensor driver");
+MODULE_LICENSE("GPL");