On Wed, Jun 16, 2021 at 08:15:45PM +0200, Emil Renner Berthing wrote:

Register definitions based on sfctemp driver in the StarFive
5.10 kernel by Samin Guo [off-list ref].

Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
---

@Samin: Only the register definitions and conversion constants are left
from your driver, but still it would be really nice if you could reply
to this mail with your Signed-off-by. Thanks!


 drivers/hwmon/Kconfig   |   9 ++
 drivers/hwmon/Makefile  |   1 +
 drivers/hwmon/sfctemp.c | 309 ++++++++++++++++++++++++++++++++++++++++

Documentation/hwmon/sfctemp is missing.

This may work on some systems, but on others it will result in:

drivers/hwmon/sfctemp.c: In function ‘sfctemp_power_up’:
drivers/hwmon/sfctemp.c:76:2: error: implicit declaration of function ‘writel’

drivers/hwmon/sfctemp.c: In function ‘sfctemp_convert’:
drivers/hwmon/sfctemp.c:144:17: error: implicit declaration of function ‘readl’

It is necessary to include <linux/io.h>.

+
+/* TempSensor reset. The RSTN can be de-asserted once the analog core has
+ * powered up. Trst(min 100ns)
+ * 0:reset  1:de-assert */

/*
 * Please use standard multi-line comments.
 * checkpatch would tell you, plus it has other complaints.
 * Please run checkpatch --strict and fix what it reports.
 */

+#define SFCTEMP_RSTN     BIT(0)
+
+/* TempSensor analog core power down. The analog core will be powered up
+ * Tpu(min 50us) after PD is de-asserted. RSTN should be held low until the
+ * analog core is powered up.
+ * 0:power up  1:power down */
+#define SFCTEMP_PD       BIT(1)
+
+/* TempSensor start conversion enable.
+ * 0:disable  1:enable */
+#define SFCTEMP_RUN      BIT(2)
+
+/* TempSensor calibration mode enable.
+ * 0:disable  1:enable */
+#define SFCTEMP_CAL      BIT(4)
+
+/* TempSensor signature enable. Generate a toggle value outputting on DOUT for
+ * test purpose.
+ * 0:disable  1:enable */
+#define SFCTEMP_SGN      BIT(5)
+
+/* TempSensor test access control.
+ * 0000:normal 0001:Test1  0010:Test2  0011:Test3
+ * 0100:Test4  1000:Test8  1001:Test9 */
+#define SFCTEMP_TM_Pos   12
+#define SFCTEMP_TM_Msk   GENMASK(15, 12)

Defines should upper case. Besides, the above defines are not
used. Please remove unused defines, and please rename the others
to be upper case only.

+
+/* TempSensor conversion value output.
+ * Temp(c)=DOUT*Y/4094 - K */
+#define SFCTEMP_DOUT_Pos 16
+#define SFCTEMP_DOUT_Msk GENMASK(27, 16)
+
+/* TempSensor digital test output. */
+#define SFCTEMP_DIGO     BIT(31)
+
+/* DOUT to Celcius conversion constants */
+#define SFCTEMP_Y1000 237500L
+#define SFCTEMP_Z       4094L

Please use

#define<space><definition><tab><value>, eg

#define SFCTEMP_Y1000	237500L
#define SFCTEMP_Z	4094L

for all defines.

+#define SFCTEMP_K1000  81100L
+
+struct sfctemp {
+	struct mutex lock;
+	struct completion conversion_done;
+	void __iomem *regs;
+	bool enabled;
+};
+
+static irqreturn_t sfctemp_isr(int irq, void *data)
+{
+	struct sfctemp *sfctemp = data;
+
+	complete(&sfctemp->conversion_done);
+	return IRQ_HANDLED;
+}
+
+static void sfctemp_power_up(struct sfctemp *sfctemp)
+{
+	/* make sure we're powered down first */
+	writel(SFCTEMP_PD, sfctemp->regs);
+	udelay(1);
+
+	writel(0, sfctemp->regs);
+	/* wait t_pu(50us) + t_rst(100ns) */
+	usleep_range(60, 200);
+
+	/* de-assert reset */
+	writel(SFCTEMP_RSTN, sfctemp->regs);
+	udelay(1); /* wait t_su(500ps) */
+}
+
+static void sfctemp_power_down(struct sfctemp *sfctemp)
+{
+	writel(SFCTEMP_PD, sfctemp->regs);
+}
+
+static void sfctemp_run_single(struct sfctemp *sfctemp)
+{
+	writel(SFCTEMP_RSTN | SFCTEMP_RUN, sfctemp->regs);
+	udelay(1);
+	writel(SFCTEMP_RSTN, sfctemp->regs);
+}
+
+static int sfctemp_enable(struct sfctemp *sfctemp)
+{
+	mutex_lock(&sfctemp->lock);
+	if (sfctemp->enabled)
+		goto done;
+
+	sfctemp_power_up(sfctemp);
+	sfctemp->enabled = true;
+done:
+	mutex_unlock(&sfctemp->lock);
+	return 0;
+}
+
+static int sfctemp_disable(struct sfctemp *sfctemp)
+{
+	mutex_lock(&sfctemp->lock);
+	if (!sfctemp->enabled)
+		goto done;
+
+	sfctemp_power_down(sfctemp);
+	sfctemp->enabled = false;
+done:
+	mutex_unlock(&sfctemp->lock);
+	return 0;
+}
+
+static int sfctemp_convert(struct sfctemp *sfctemp, long *val)
+{
+	long ret;

Why long ? Sure, wait_for_completion_interruptible_timeout()
returns a long, but it will never return a value large enough to warrant
a long here.

+
+	mutex_lock(&sfctemp->lock);
+	if (!sfctemp->enabled) {
+		ret = -ENODATA;
+		goto out;
+	}
+
+	sfctemp_run_single(sfctemp);
+
+	ret = wait_for_completion_interruptible_timeout(&sfctemp->conversion_done,
+			                                msecs_to_jiffies(10));
+	if (ret < 0)
+		goto out;
+
+	/* calculate temperature in milli Celcius */
+	*val = (long)((readl(sfctemp->regs) & SFCTEMP_DOUT_Msk) >> SFCTEMP_DOUT_Pos)
+		* SFCTEMP_Y1000 / SFCTEMP_Z - SFCTEMP_K1000;
+
+	ret = 0;
+out:
+	mutex_unlock(&sfctemp->lock);
+	return ret;
+}
+
+static umode_t sfctemp_is_visible(const void *data, enum hwmon_sensor_types type,
+				  u32 attr, int channel)
+{
+	switch (type) {
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_enable:
+			return 0644;
+		case hwmon_temp_input:
+			return 0444;
+		}
+		return 0;
+	default:
+		return 0;
+	}
+}
+
+static int sfctemp_read(struct device *dev, enum hwmon_sensor_types type,
+			u32 attr, int channel, long *val)
+{
+	struct sfctemp *sfctemp = dev_get_drvdata(dev);
+
+	switch (type) {
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_enable:
+			*val = sfctemp->enabled;
+			return 0;
+		case hwmon_temp_input:
+			return sfctemp_convert(sfctemp, val);
+		}
+		return -EINVAL;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int sfctemp_write(struct device *dev, enum hwmon_sensor_types type,
+			 u32 attr, int channel, long val)
+{
+	struct sfctemp *sfctemp = dev_get_drvdata(dev);
+
+	switch (type) {
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_enable:
+			if (val == 0)
+				return sfctemp_disable(sfctemp);
+			if (val == 1)
+				return sfctemp_enable(sfctemp);
+			break;
+		}
+		return -EINVAL;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct hwmon_channel_info *sfctemp_info[] = {
+	HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
+	HWMON_CHANNEL_INFO(temp, HWMON_T_ENABLE | HWMON_T_INPUT),
+	NULL
+};
+
+static const struct hwmon_ops sfctemp_hwmon_ops = {
+	.is_visible = sfctemp_is_visible,
+	.read = sfctemp_read,
+	.write = sfctemp_write,
+};
+
+static const struct hwmon_chip_info sfctemp_chip_info = {
+	.ops = &sfctemp_hwmon_ops,
+	.info = sfctemp_info,
+};
+
+static int sfctemp_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device *hwmon_dev;
+	struct resource *mem;
+	struct sfctemp *sfctemp;
+	long val;
+	int ret;
+
+	sfctemp = devm_kzalloc(dev, sizeof(*sfctemp), GFP_KERNEL);
+	if (!sfctemp)
+		return -ENOMEM;
+
+	dev_set_drvdata(dev, sfctemp);
+	mutex_init(&sfctemp->lock);
+	init_completion(&sfctemp->conversion_done);
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	sfctemp->regs = devm_ioremap_resource(dev, mem);
+	if (IS_ERR(sfctemp->regs))
+		return PTR_ERR(sfctemp->regs);
+
+	ret = platform_get_irq(pdev, 0);
+	if (ret < 0)
+		return ret;
+
+	ret = devm_request_irq(dev, ret, sfctemp_isr,
+			       IRQF_SHARED, pdev->name, sfctemp);
+	if (ret) {
+		dev_err(dev, "request irq failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = sfctemp_enable(sfctemp);
+	if (ret)
+		return ret;

Please consider adding devm_add_action_or_reset() to disable the sensor.
Then you can use devm_hwmon_device_register_with_info(), and there is
no need for a remove function.

+
+	hwmon_dev = hwmon_device_register_with_info(dev, pdev->name, sfctemp,
+						    &sfctemp_chip_info, NULL);
+	if (IS_ERR(hwmon_dev))
+		return PTR_ERR(hwmon_dev);
+
+	/* do a conversion to check everything works */
+	ret = sfctemp_convert(sfctemp, &val);

Please drop this check; it will result in substantial boot delays.
The assumption is the the hardware works; the system should not be
optimized (slowed down) to handle a potential and hopefully rare
failure case.

+	if (ret) {
+		hwmon_device_unregister(hwmon_dev);
+		return ret;
+	}
+
+	dev_info(dev, "%ld.%03ld C\n", val / 1000, val % 1000);

Please drop this message. Anyone interested in boot-time temperature
readings can add a script and get it from sysfs attributes as needed.

+	return 0;
+}
+
+static int sfctemp_remove(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct sfctemp *sfctemp = dev_get_drvdata(dev);
+
+	hwmon_device_unregister(dev);
+	return sfctemp_disable(sfctemp);
+}
+
+static const struct of_device_id sfctemp_of_match[] = {
+	{ .compatible = "starfive,jh7100-temp" },
+	{ /* sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(of, sfctemp_of_match);
+
+static struct platform_driver sfctemp_driver = {
+	.driver = {
+		.name = "sfctemp",
+		.of_match_table = of_match_ptr(sfctemp_of_match),
+	},
+	.probe  = sfctemp_probe,
+	.remove = sfctemp_remove,
+};
+module_platform_driver(sfctemp_driver);
+
+MODULE_AUTHOR("Emil Renner Berthing");
+MODULE_DESCRIPTION("StarFive JH7100 temperature sensor driver");
+MODULE_LICENSE("GPL");
-- 
2.32.0