Re: [PATCH 1/2] hwmon: (ltq-cputemp) add cpu temp sensor for xrx200
From: Guenter Roeck
Date: Fri Aug 18 2017 - 02:05:38 EST
On 08/17/2017 05:53 AM, Florian Eckert wrote:
Add the lantiq cpu temperature sensor support for xrx200.
Signed-off-by: Florian Eckert <fe@xxxxxxxxxx>
---
drivers/hwmon/Kconfig | 8 +++
drivers/hwmon/Makefile | 1 +
drivers/hwmon/ltq-cputemp.c | 155 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 164 insertions(+)
create mode 100644 drivers/hwmon/ltq-cputemp.c
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 5ef2814345ef..ed3f5e1d10cc 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -790,6 +790,14 @@ 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 for xrx200"
+ depends on LANTIQ
+ default n
n is already the default. No need to specify it.
+ help
+ If you say yes here you get support for the temperature
+ sensor inside your xrx200 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..a6f820533164
--- /dev/null
+++ b/drivers/hwmon/ltq-cputemp.c
@@ -0,0 +1,155 @@
+/* Lantiq cpu temperature sensor driver for xrx200
+ *
+ * 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);
+
+ /* wait a short moment to let the SoC get the first temperatur value */
temperature
+ mdelay(100);
An active delay during boot doesn't sound like a good idea to me.
It might be better to mark the time and add an msleep() into the read
function if called too early.
+}
+
+static void ltq_cputemp_disable(void)
+{
+ ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) & ~CGU_TEMP_PD, CGU_GPHY1_CR);
+}
+
+static int ltq_cputemp_read(void)
+{
+ int value;
+
+ /* get the temperature including one decimal place */
+ value = (ltq_cgu_r32(CGU_GPHY1_CR) >> 9) & 0x01FF;
+ value = (value << 2) + value;
+
Can you just multiply times 5 and leave the optimization to the compiler ?
This would be much easier to understand.
+ /* range -38 to +154 ÂC, register value zero is -38.0 ÂC */
+ value -= 380;
+
+ return value;
+}
+
+static ssize_t show_cputemp(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ int value;
+
+ value = ltq_cputemp_read();
+ /* scale temp to millidegree */
+ value = value * 100;
+
+ return sprintf(buf, "%d\n", value);
+}
+
+static DEVICE_ATTR(temp1_input, S_IRUGO, show_cputemp, NULL);
+
+static struct attribute *ltq_cputemp_attrs[] = {
+ &dev_attr_temp1_input.attr,
+ NULL
+};
+
+ATTRIBUTE_GROUPS(ltq_cputemp);
+
+static int ltq_cputemp_probe(struct platform_device *pdev)
+{
+ int value = 0;
Unnecessary initialization.
+ int ret;
+ struct device *hwmon_dev;
+
+ /* available on vr9 v1.2 SoCs only */
+ if (ltq_soc_type() != SOC_TYPE_VR9_2)
+ return -ENODEV;
+
Any chance to make this a bit more generic ? It is quite likely that
later SOC revisions will support it as well, meaning we'll have to
repeatedly touch the driver.
+ hwmon_dev = devm_hwmon_device_register_with_groups(&pdev->dev,
+ "CPU0",
+ NULL,
+ ltq_cputemp_groups);
Please consider using devm_hwmon_device_register_with_info() instead.
This driver looks like an excellent fit for the new API.
+
+ if (IS_ERR(hwmon_dev)) {
+ dev_err(&pdev->dev, "Failed to register as hwmon device");
+ ret = PTR_ERR(hwmon_dev);
+ goto error_hwmon;
Unnecessary goto. Just return.
+ }
+
+ ltq_cputemp_enable();
+ value = ltq_cputemp_read();
+ dev_info(&pdev->dev,
+ "Current CPU die temperature: %d.%d ÂC",
+ value / 10,
+ value % 10);
Highly unusual, even more so since it requires an active 100 ms delay during boot.
Please drop.
+
+ return 0;
+
+error_hwmon:
+ return ret;
+}
+
+static int ltq_cputemp_release(struct platform_device *pdev)
+{
+ hwmon_device_unregister(&pdev->dev);
This is done automatically (or don't the the devm function to register it).
Besides, it takes the hwmon device as argument.
+ 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",
+ .owner = THIS_MODULE,
AFAIK this is no longer necessary.
+ .of_match_table = ltq_cputemp_match,
+ },
+};
+
+int __init init_ltq_cputemp(void)
+{
+ int ret;
+
+ ret = platform_driver_register(<q_cputemp_driver);
+ return ret;
Unnecessary variable. I am quite sure there is a template for this code, though.
+}
+
+void clean_ltq_cputemp(void)
+{
+ platform_driver_unregister(<q_cputemp_driver);
+}
+
+module_init(init_ltq_cputemp);
+module_exit(clean_ltq_cputemp);
module_platform_driver ?
+
+MODULE_AUTHOR("Florian Eckert <fe@xxxxxxxxxx>");
+MODULE_DESCRIPTION("Lantiq Temperature Sensor");
+MODULE_LICENSE("GPL");