apml_sbtsi.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * apml_sbtsi.c - hwmon driver for a SBI Temperature Sensor Interface (SB-TSI)
 *                compliant AMD SoC temperature device.
 * 		   Also register to misc driver with an IOCTL.
 *
 * Copyright (c) 2020, Google Inc.
 * Copyright (c) 2020, Kun Yi <kunyi@google.com>
 * Copyright (C) 2022 Advanced Micro Devices, Inc.
 */

#include <linux/err.h>
#include <linux/fs.h>
#include <linux/hwmon.h>
#include <linux/i3c/device.h>
#include <linux/i3c/master.h>
#include <linux/init.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/minmax.h>
#include <linux/mutex.h>
#include <linux/of_device.h>
#include <linux/of.h>
#include <linux/regmap.h>
#include <linux/version.h>

#include "amd-apml.h"

/*
 * SB-TSI registers only support SMBus byte data access. "_INT" registers are
 * the integer part of a temperature value or limit, and "_DEC" registers are
 * corresponding decimal parts.
 */
#define SBTSI_REG_TEMP_INT		0x01 /* RO */
#define SBTSI_REG_STATUS		0x02 /* RO */
#define SBTSI_REG_CONFIG		0x03 /* RO */
#define SBTSI_REG_TEMP_HIGH_INT		0x07 /* RW */
#define SBTSI_REG_TEMP_LOW_INT		0x08 /* RW */
#define SBTSI_REG_TEMP_DEC		0x10 /* RW */
#define SBTSI_REG_TEMP_HIGH_DEC		0x13 /* RW */
#define SBTSI_REG_TEMP_LOW_DEC		0x14 /* RW */

#define SBTSI_CONFIG_READ_ORDER_SHIFT	5

#define SBTSI_TEMP_MIN	0
#define SBTSI_TEMP_MAX	255875

/*
 * SBTSI_STEP_INC Fractional portion of temperature
 * One increment of these bits is equivalent to a step of 0.125 °C
 *
 * SBTSI_INT_OFFSET Integer offset for temperature value
 *
 * SBTSI_DEC_OFFSET offset for decimal bits in register[7:5]
 *
 * SBTSI_DEC_MASK Mask for decimal value
 */
#define SBTSI_STEP_INC		125
#define SBTSI_INT_OFFSET	3
#define SBTSI_DEC_OFFSET	5
#define SBTSI_DEC_MASK		0x7

struct apml_sbtsi_device {
	struct miscdevice sbtsi_misc_dev;
	struct regmap *regmap;
	struct mutex lock;
	u8 dev_static_addr;
	atomic_t in_progress;
	atomic_t no_new_trans;
	struct completion misc_fops_done;
} __packed;

/*
 * From SB-TSI spec: CPU temperature readings and limit registers encode the
 * temperature in increments of 0.125 from 0 to 255.875. The "high byte"
 * register encodes the base-2 of the integer portion, and the upper 3 bits of
 * the "low byte" encode in base-2 the decimal portion.
 *
 * e.g. INT=0x19, DEC=0x20 represents 25.125 degrees Celsius
 *
 * Therefore temperature in millidegree Celsius =
 *   (INT + DEC / 256) * 1000 = (INT * 8 + DEC / 32) * 125
 */
static inline int sbtsi_reg_to_mc(s32 integer, s32 decimal)
{
	return ((integer << SBTSI_INT_OFFSET) +
	       (decimal >> SBTSI_DEC_OFFSET)) * SBTSI_STEP_INC;
}

/*
 * Inversely, given temperature in millidegree Celsius
 *   INT = (TEMP / 125) / 8
 *   DEC = ((TEMP / 125) % 8) * 32
 * Caller have to make sure temp doesn't exceed 255875, the max valid value.
 */
static inline void sbtsi_mc_to_reg(s32 temp, u8 *integer, u8 *decimal)
{
	temp /= SBTSI_STEP_INC;
	*integer = temp >> SBTSI_INT_OFFSET;
	*decimal = (temp & SBTSI_DEC_MASK) << SBTSI_DEC_OFFSET;
}

static int sbtsi_prepare_lock(struct apml_sbtsi_device *tsi_dev)
{
	mutex_lock(&tsi_dev->lock);
	/* Verify device unbind/remove is not invoked */
	if (atomic_read(&tsi_dev->no_new_trans)) {
		mutex_unlock(&tsi_dev->lock);
		return -EBUSY;
	}

	/*
	 * Set the in_progress variable to true, to wait for
	 * completion during unbind/remove of driver
	 */
	atomic_set(&tsi_dev->in_progress, 1);
	return 0;
}

static void sbtsi_prepare_unlock(struct apml_sbtsi_device *tsi_dev)
{
	/* Send complete only if device is unbinded/remove */
	if (atomic_read(&tsi_dev->no_new_trans))
		complete(&tsi_dev->misc_fops_done);

	atomic_set(&tsi_dev->in_progress, 0);
	mutex_unlock(&tsi_dev->lock);
}

static int sbtsi_read(struct device *dev, enum hwmon_sensor_types type,
		      u32 attr, int channel, long *val)
{
	struct apml_sbtsi_device *tsi_dev = dev_get_drvdata(dev);
	unsigned int temp_int, temp_dec, cfg;
	int ret;

	/*
	 * If device remove/unbind is called do not allow new transaction
	 */
	if (atomic_read(&tsi_dev->no_new_trans))
		return -EBUSY;

	switch (attr) {
	case hwmon_temp_input:
		/*
		 * ReadOrder bit specifies the reading order of integer and
		 * decimal part of CPU temp for atomic reads. If bit == 0,
		 * reading integer part triggers latching of the decimal part,
		 * so integer part should be read first. If bit == 1, read
		 * order should be reversed.
		 */
		ret = regmap_read(tsi_dev->regmap, SBTSI_REG_CONFIG, &cfg);
		if (ret < 0)
			return ret;

		ret = sbtsi_prepare_lock(tsi_dev);
		if (ret)
			return ret;

		if (cfg & BIT(SBTSI_CONFIG_READ_ORDER_SHIFT)) {
			ret = regmap_read(tsi_dev->regmap, SBTSI_REG_TEMP_DEC, &temp_dec);
			ret = regmap_read(tsi_dev->regmap, SBTSI_REG_TEMP_INT, &temp_int);
		} else {
			ret = regmap_read(tsi_dev->regmap, SBTSI_REG_TEMP_INT, &temp_int);
			ret = regmap_read(tsi_dev->regmap, SBTSI_REG_TEMP_DEC, &temp_dec);
		}

		sbtsi_prepare_unlock(tsi_dev);
		break;
	case hwmon_temp_max:
		ret = sbtsi_prepare_lock(tsi_dev);
		if (ret)
			return ret;

		ret = regmap_read(tsi_dev->regmap, SBTSI_REG_TEMP_HIGH_INT, &temp_int);
		ret = regmap_read(tsi_dev->regmap, SBTSI_REG_TEMP_HIGH_DEC, &temp_dec);

		sbtsi_prepare_unlock(tsi_dev);
		break;
	case hwmon_temp_min:
		ret = sbtsi_prepare_lock(tsi_dev);
		if (ret)
			return ret;

		ret = regmap_read(tsi_dev->regmap, SBTSI_REG_TEMP_LOW_INT, &temp_int);
		ret = regmap_read(tsi_dev->regmap, SBTSI_REG_TEMP_LOW_DEC, &temp_dec);

		sbtsi_prepare_unlock(tsi_dev);
		break;
	default:
		return -EINVAL;
	}

	if (ret < 0)
		return ret;

	*val = sbtsi_reg_to_mc(temp_int, temp_dec);

	return 0;
}

static int sbtsi_write(struct device *dev, enum hwmon_sensor_types type,
		       u32 attr, int channel, long val)
{
	struct apml_sbtsi_device *tsi_dev = dev_get_drvdata(dev);
	unsigned int temp_int, temp_dec;
	int reg_int, reg_dec, err;

	/*
	 * If device remove/unbind is called do not allow new transaction
	 */
	if (atomic_read(&tsi_dev->no_new_trans))
		return -EBUSY;

	switch (attr) {
	case hwmon_temp_max:
		reg_int = SBTSI_REG_TEMP_HIGH_INT;
		reg_dec = SBTSI_REG_TEMP_HIGH_DEC;
		break;
	case hwmon_temp_min:
		reg_int = SBTSI_REG_TEMP_LOW_INT;
		reg_dec = SBTSI_REG_TEMP_LOW_DEC;
		break;
	default:
		return -EINVAL;
	}

	val = clamp_val(val, SBTSI_TEMP_MIN, SBTSI_TEMP_MAX);
	sbtsi_mc_to_reg(val, (u8 *)&temp_int, (u8 *)&temp_dec);

	err = sbtsi_prepare_lock(tsi_dev);
	if (err)
		return err;

	err = regmap_write(tsi_dev->regmap, reg_int, temp_int);
	if (err)
		goto exit;

	err = regmap_write(tsi_dev->regmap, reg_dec, temp_dec);
exit:
	sbtsi_prepare_unlock(tsi_dev);
	return err;
}

static umode_t sbtsi_is_visible(const void *data,
				enum hwmon_sensor_types type,
				u32 attr, int channel)
{
	switch (type) {
	case hwmon_temp:
		switch (attr) {
		case hwmon_temp_input:
			return 0444;
		case hwmon_temp_min:
			return 0644;
		case hwmon_temp_max:
			return 0644;
		}
		break;
	default:
		break;
	}
	return 0;
}

static const struct hwmon_channel_info *sbtsi_info[] = {
	HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX),
	NULL
};

static const struct hwmon_ops sbtsi_hwmon_ops = {
	.is_visible = sbtsi_is_visible,
	.read = sbtsi_read,
	.write = sbtsi_write,
};

static const struct hwmon_chip_info sbtsi_chip_info = {
	.ops = &sbtsi_hwmon_ops,
	.info = sbtsi_info,
};

static long sbtsi_ioctl(struct file *fp, unsigned int cmd, unsigned long arg)
{
	int __user *arguser = (int  __user *)arg;
	struct apml_message msg = { 0 };
	struct apml_sbtsi_device *tsi_dev;
	int ret;

	if (copy_struct_from_user(&msg, sizeof(msg), arguser, sizeof(struct apml_message)))
		return -EFAULT;

	if (msg.cmd != APML_REG)
		return -EINVAL;

	tsi_dev = container_of(fp->private_data, struct apml_sbtsi_device, sbtsi_misc_dev);
	if (!tsi_dev)
		return -EFAULT;

	/*
	 * If device remove/unbind is called do not allow new transaction
	 */
	if (atomic_read(&tsi_dev->no_new_trans))
		return -EBUSY;

	ret = sbtsi_prepare_lock(tsi_dev);
	if (ret)
		return ret;

	if (!msg.data_in.reg_in[RD_FLAG_INDEX]) {
		ret = regmap_write(tsi_dev->regmap,
				   msg.data_in.reg_in[REG_OFF_INDEX],
				   msg.data_in.reg_in[REG_VAL_INDEX]);
	} else {
		ret = regmap_read(tsi_dev->regmap,
				  msg.data_in.reg_in[REG_OFF_INDEX],
				  (int *)&msg.data_out.reg_out[RD_WR_DATA_INDEX]);
		if (ret)
			goto out;

		if (copy_to_user(arguser, &msg, sizeof(struct apml_message)))
			ret = -EFAULT;
	}
out:
	sbtsi_prepare_unlock(tsi_dev);
	return ret;
}

static const struct file_operations sbtsi_fops = {
	.owner		= THIS_MODULE,
	.unlocked_ioctl	= sbtsi_ioctl,
	.compat_ioctl	= sbtsi_ioctl,
};

static int create_misc_tsi_device(struct apml_sbtsi_device *tsi_dev,
				  struct device *dev)
{
	int ret;

	tsi_dev->sbtsi_misc_dev.name		= devm_kasprintf(dev, GFP_KERNEL,
						  "sbtsi-%x", tsi_dev->dev_static_addr);
	tsi_dev->sbtsi_misc_dev.minor		= MISC_DYNAMIC_MINOR;
	tsi_dev->sbtsi_misc_dev.fops		= &sbtsi_fops;
	tsi_dev->sbtsi_misc_dev.parent		= dev;
	tsi_dev->sbtsi_misc_dev.nodename	= devm_kasprintf(dev, GFP_KERNEL,
						  "sbtsi-%x", tsi_dev->dev_static_addr);
	tsi_dev->sbtsi_misc_dev.mode		= 0600;

	ret = misc_register(&tsi_dev->sbtsi_misc_dev);
	if (ret)
		return ret;

	dev_info(dev, "register %s device\n", tsi_dev->sbtsi_misc_dev.name);
	return ret;
}

static int sbtsi_i3c_probe(struct i3c_device *i3cdev)
{
	struct device *dev = &i3cdev->dev;
	struct device *hwmon_dev;
	struct apml_sbtsi_device *tsi_dev;
	struct regmap_config sbtsi_i3c_regmap_config = {
		.reg_bits = 8,
		.val_bits = 8,
	};
	struct regmap *regmap;
	const char *name;

	if (!(I3C_PID_INSTANCE_ID(i3cdev->desc->info.pid) == 0 ||
	    i3cdev->desc->info.pid == 0x22400000001))
		return -ENXIO;

	regmap = devm_regmap_init_i3c(i3cdev, &sbtsi_i3c_regmap_config);
	if (IS_ERR(regmap)) {
		dev_err(&i3cdev->dev, "Failed to register i3c regmap %d\n",
			(int)PTR_ERR(regmap));
		return PTR_ERR(regmap);
	}

	tsi_dev = devm_kzalloc(dev, sizeof(struct apml_sbtsi_device), GFP_KERNEL);
	if (!tsi_dev)
		return -ENOMEM;

	atomic_set(&tsi_dev->in_progress, 0);
	atomic_set(&tsi_dev->no_new_trans, 0);
	tsi_dev->regmap = regmap;
	mutex_init(&tsi_dev->lock);

	dev_set_drvdata(dev, (void *)tsi_dev);

	/* Need to verify for the static address for i3cdev */
	tsi_dev->dev_static_addr = i3cdev->desc->info.static_addr;

	switch(tsi_dev->dev_static_addr) {
	case 0x4c:
		name = devm_kasprintf(dev, GFP_KERNEL, "sbtsi_%s", "0.0");
		break;
	case 0x48:
		name = devm_kasprintf(dev, GFP_KERNEL, "sbtsi_%s", "1.0");
		break;
	default:
		name = devm_kasprintf(dev, GFP_KERNEL, "sbtsi_");
		break;
	}

	hwmon_dev = devm_hwmon_device_register_with_info(dev, name, tsi_dev,
							 &sbtsi_chip_info, NULL);

	if (!hwmon_dev)
		return PTR_ERR_OR_ZERO(hwmon_dev);

	init_completion(&tsi_dev->misc_fops_done);
	return create_misc_tsi_device(tsi_dev, dev);
}

#if LINUX_VERSION_CODE < KERNEL_VERSION(6, 3, 0)
static int sbtsi_i2c_probe(struct i2c_client *client,
			   const struct i2c_device_id *tsi_id)
#else
static int sbtsi_i2c_probe(struct i2c_client *client)
#endif
{
	struct device *dev = &client->dev;
	struct device *hwmon_dev;
	struct apml_sbtsi_device *tsi_dev;
	struct regmap_config sbtsi_i2c_regmap_config = {
		.reg_bits = 8,
		.val_bits = 8,
	};
	const char *name;

	tsi_dev = devm_kzalloc(dev, sizeof(struct apml_sbtsi_device), GFP_KERNEL);
	if (!tsi_dev)
		return -ENOMEM;

	atomic_set(&tsi_dev->in_progress, 0);
	atomic_set(&tsi_dev->no_new_trans, 0);
	mutex_init(&tsi_dev->lock);
	tsi_dev->regmap = devm_regmap_init_i2c(client, &sbtsi_i2c_regmap_config);
	if (IS_ERR(tsi_dev->regmap))
		return PTR_ERR(tsi_dev->regmap);

	dev_set_drvdata(dev, (void *)tsi_dev);

	tsi_dev->dev_static_addr = client->addr;

	switch(tsi_dev->dev_static_addr) {
	case 0x4c:
		name = devm_kasprintf(dev, GFP_KERNEL, "sbtsi_%s", "0.0");
		break;
	case 0x48:
		name = devm_kasprintf(dev, GFP_KERNEL, "sbtsi_%s", "1.0");
		break;
	default:
		name = devm_kasprintf(dev, GFP_KERNEL, "sbtsi_");
		break;
	}

	hwmon_dev = devm_hwmon_device_register_with_info(dev, name,
							 tsi_dev,
							 &sbtsi_chip_info,
							 NULL);

	if (!hwmon_dev)
		return PTR_ERR_OR_ZERO(hwmon_dev);

	init_completion(&tsi_dev->misc_fops_done);
	return create_misc_tsi_device(tsi_dev, dev);
}

#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 12, 0)
static int sbtsi_i3c_remove(struct i3c_device *i3cdev)
#else
static void sbtsi_i3c_remove(struct i3c_device *i3cdev)
#endif
{
	struct apml_sbtsi_device *tsi_dev = dev_get_drvdata(&i3cdev->dev);

	if (!tsi_dev)
#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 12, 0)
		return 0;
#else
		return;
#endif

	/*
	 * Set the no_new_trans so no new transaction can
	 * occur in sbtsi functions
	 */
	atomic_set(&tsi_dev->no_new_trans, 1);
	/*
	 * If any transaction is in progress wait for the
	 * transaction to get complete
	 * Max wait is 3 sec for any pending transaction to
	 * complete
	 */
	if (atomic_read(&tsi_dev->in_progress))
		wait_for_completion_timeout(&tsi_dev->misc_fops_done,
					    3 * HZ);
	misc_deregister(&tsi_dev->sbtsi_misc_dev);
	/* Assign fops and parent of misc dev to NULL */
	tsi_dev->sbtsi_misc_dev.fops = NULL;
	tsi_dev->sbtsi_misc_dev.parent = NULL;

	dev_info(&i3cdev->dev, "Removed sbtsi-i3c driver\n");
#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 12, 0)
	return 0;
#endif
}

#if LINUX_VERSION_CODE < KERNEL_VERSION(6, 1, 0)
static int sbtsi_i2c_remove(struct i2c_client *client)
#else
static void sbtsi_i2c_remove(struct i2c_client *client)
#endif
{
	struct apml_sbtsi_device *tsi_dev = dev_get_drvdata(&client->dev);

	if (!tsi_dev)
#if LINUX_VERSION_CODE < KERNEL_VERSION(6, 1, 0)
		return 0;
#else
		return;
#endif

	/*
	 * Set the no_new_trans so no new transaction can
	 * occur in sbtsi functions
	 */
	atomic_set(&tsi_dev->no_new_trans, 1);
	/*
	 * If any transaction is in progress wait for the
	 * transaction to get complete
	 * Max wait is 3 sec for any pending transaction to
	 * complete
	 */
	if (atomic_read(&tsi_dev->in_progress))
		wait_for_completion_timeout(&tsi_dev->misc_fops_done,
					    3 * HZ);
	misc_deregister(&tsi_dev->sbtsi_misc_dev);
	/* Assign fops and parent of misc dev to NULL */
	tsi_dev->sbtsi_misc_dev.fops = NULL;
	tsi_dev->sbtsi_misc_dev.parent = NULL;

	dev_info(&client->dev, "Removed sbtsi driver\n");
#if LINUX_VERSION_CODE < KERNEL_VERSION(6, 1, 0)
	return 0;
#endif
}

static const struct i3c_device_id sbtsi_i3c_id[] = {
	I3C_DEVICE_EXTRA_INFO(0x112, 0, 0x1, NULL),
	{}
};
MODULE_DEVICE_TABLE(i3c, sbtsi_i3c_id);

static struct i3c_driver sbtsi_i3c_driver = {
	.driver = {
		.name = "sbtsi_i3c",
	},
	.probe = sbtsi_i3c_probe,
	.remove = sbtsi_i3c_remove,
	.id_table = sbtsi_i3c_id,
};

static const struct i2c_device_id sbtsi_id[] = {
	{"sbtsi", 0},
	{}
};
MODULE_DEVICE_TABLE(i2c, sbtsi_id);

static const struct of_device_id __maybe_unused sbtsi_of_match[] = {
	{
		.compatible = "amd,sbtsi",
	},
	{ },
};
MODULE_DEVICE_TABLE(of, sbtsi_of_match);

static struct i2c_driver sbtsi_driver = {
	.class = I2C_CLASS_HWMON,
	.driver = {
		.name = "sbtsi",
		.of_match_table = of_match_ptr(sbtsi_of_match),
	},
	.probe = sbtsi_i2c_probe,
	.remove = sbtsi_i2c_remove,
	.id_table = sbtsi_id,
};

module_i3c_i2c_driver(sbtsi_i3c_driver, &sbtsi_driver)

MODULE_AUTHOR("Kun Yi <kunyi@google.com>");
MODULE_DESCRIPTION("Hwmon driver for AMD SB-TSI emulated sensor");
MODULE_LICENSE("GPL");