On Sat, 05 Sep 2020, Jonathan Neuschäfer wrote:

Nit: "Embedded Controller (EC)"

+	depends on I2C && OF

	depends on (I2C && OF) || COMPILE_TEST

Why 2 only?

+/*
+ * The Netronix embedded controller is a microcontroller found in some
+ * e-book readers designed by the ODM Netronix, Inc. It contains RTC,
+ * battery monitoring, system power management, and PWM functionality.
+ *
+ * This driver implements register access, version detection, and system
+ * power-off/reset.
+ *
+ * Copyright 2020 Jonathan Neuschäfer

Email?

+ */
+
+#include <asm/unaligned.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/i2c.h>
+#include <linux/mfd/ntxec.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/pm.h>
+#include <linux/reboot.h>
+#include <linux/regmap.h>
+#include <linux/types.h>
+
+#define NTXEC_REG_VERSION	0x00
+#define NTXEC_REG_POWEROFF	0x50
+#define NTXEC_REG_POWERKEEP	0x70
+#define NTXEC_REG_RESET		0x90
+
+#define NTXEC_POWEROFF_VALUE	0x0100
+#define NTXEC_POWERKEEP_VALUE	0x0800
+#define NTXEC_RESET_VALUE	0xff00
+
+static struct i2c_client *poweroff_restart_client;
+
+static void ntxec_poweroff(void)
+{
+	int res;
+

Remove this line please.

+	u8 buf[] = {
+		NTXEC_REG_POWEROFF,
+		(NTXEC_POWEROFF_VALUE >> 8) & 0xff,
+		NTXEC_POWEROFF_VALUE & 0xff,
+	};
+

And this one.

+	struct i2c_msg msgs[] = {
+		{
+			.addr = poweroff_restart_client->addr,
+			.flags = 0,
+			.len = sizeof(buf),
+			.buf = buf
+		}
+	};
+
+	res = i2c_transfer(poweroff_restart_client->adapter, msgs, ARRAY_SIZE(msgs));
+

And this one.

+	if (res < 0)
+		dev_alert(&poweroff_restart_client->dev, "Failed to power off (err = %d)\n", res);

This looks way over 80 chars.

Did you run checkpatch.pl?

+	/*
+	 * The time from the register write until the host CPU is powered off
+	 * has been observed to be about 2.5 to 3 seconds. Sleep long enough to
+	 * safely avoid returning from the poweroff handler.
+	 */
+	msleep(5000);
+}
+
+static int ntxec_restart(struct notifier_block *nb,
+			 unsigned long action, void *data)
+{
+	int res;
+
+	/*
+	 * NOTE: The lower half of the reset value is not sent, because sending
+	 * it causes an error
+	 */
+	u8 buf[] = {
+		NTXEC_REG_RESET,
+		(NTXEC_RESET_VALUE >> 8) & 0xff,
+	};
+
+	struct i2c_msg msgs[] = {
+		{
+			.addr = poweroff_restart_client->addr,
+			.flags = 0,
+			.len = sizeof(buf),
+			.buf = buf
+		}
+	};
+
+	res = i2c_transfer(poweroff_restart_client->adapter, msgs, ARRAY_SIZE(msgs));
+
+	if (res < 0)
+		dev_alert(&poweroff_restart_client->dev, "Failed to restart (err = %d)\n", res);
+
+	return NOTIFY_DONE;
+}

All as above for this function.

+static struct notifier_block ntxec_restart_handler = {
+	.notifier_call = ntxec_restart,
+	.priority = 128
+};
+
+static const struct regmap_config regmap_config = {
+	.name = "ntxec",
+	.reg_bits = 8,
+	.val_bits = 16,
+	.cache_type = REGCACHE_NONE,
+	.val_format_endian = REGMAP_ENDIAN_BIG,
+};
+
+static const struct ntxec_info ntxec_known_versions[] = {
+	{ 0xd726 }, /* found in Kobo Aura */
+};
+
+static const struct ntxec_info *ntxec_lookup_info(u16 version)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(ntxec_known_versions); i++) {
+		const struct ntxec_info *info = &ntxec_known_versions[i];
+
+		if (info->version == version)
+			return info;
+	}
+
+	return NULL;
+}

Wait, what?  This is over-engineered.

Just have a look-up table (switch) of supported devices.

+static int ntxec_probe(struct i2c_client *client)
+{
+	struct ntxec *ec;
+	unsigned int version;
+	int res;
+
+	ec = devm_kmalloc(&client->dev, sizeof(*ec), GFP_KERNEL);
+	if (!ec)
+		return -ENOMEM;
+
+	ec->dev = &client->dev;
+
+	ec->regmap = devm_regmap_init_i2c(client, &regmap_config);
+	if (IS_ERR(ec->regmap)) {
+		dev_err(ec->dev, "Failed to set up regmap for device\n");
+		return res;
+	}
+
+	/* Determine the firmware version */
+	res = regmap_read(ec->regmap, NTXEC_REG_VERSION, &version);
+	if (res < 0) {
+		dev_err(ec->dev, "Failed to read firmware version number\n");
+		return res;
+	}
+	dev_info(ec->dev,
+		 "Netronix embedded controller version %04x detected.\n",
+		 version);
+
+	/* Bail out if we encounter an unknown firmware version */
+	ec->info = ntxec_lookup_info(version);
+	if (!ec->info)
+		return -EOPNOTSUPP;

#define EOPNOTSUPP      95      /* Operation not supported on transport endpoint */

I think you want:

#define ENODEV          19      /* No such device */

+	if (of_device_is_system_power_controller(ec->dev->of_node)) {
+		/*
+		 * Set the 'powerkeep' bit. This is necessary on some boards
+		 * in order to keep the system running.
+		 */
+		res = regmap_write(ec->regmap, NTXEC_REG_POWERKEEP,
+				   NTXEC_POWERKEEP_VALUE);
+		if (res < 0)
+			return res;
+
+		/* Install poweroff handler */

Don't think this comment is required.

+		WARN_ON(poweroff_restart_client);
+		poweroff_restart_client = client;
+		if (pm_power_off)
+			dev_err(ec->dev, "pm_power_off already assigned\n");
+		else
+			pm_power_off = ntxec_poweroff;
+
+		/* Install board reset handler */

Nor this.

+		res = register_restart_handler(&ntxec_restart_handler);
+		if (res)
+			dev_err(ec->dev,
+				"Failed to register restart handler: %d\n", res);
+	}
+
+	i2c_set_clientdata(client, ec);
+
+	return devm_of_platform_populate(ec->dev);
+}
+
+static int ntxec_remove(struct i2c_client *i2c)

Why do you call it 'client' in .probe, but 'i2c' in .remove?

+	const struct ntxec_info *info;

What is this used for?

+};
+
+#endif

-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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