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From:   nick.hawkins@hpe.com
To:     verdun@hpe.com, nick.hawkins@hpe.com, linus.walleij@linaro.org,
        brgl@bgdev.pl, robh+dt@kernel.org,
        krzysztof.kozlowski+dt@linaro.org, jdelvare@suse.com,
        linux@roeck-us.net, linux@armlinux.org.uk,
        linux-gpio@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-hwmon@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org
Subject: [PATCH v1 3/9] hwmon: (gxp-psu) Add driver to read HPE PSUs
Date:   Tue, 18 Apr 2023 10:28:18 -0500
Message-Id: <20230418152824.110823-4-nick.hawkins@hpe.com>
In-Reply-To: <20230418152824.110823-1-nick.hawkins@hpe.com>
References: <20230418152824.110823-1-nick.hawkins@hpe.com>
Precedence: bulk

From: Nick Hawkins <nick.hawkins@hpe.com>

The GXP SoC can support up to 8 power supplies that it can communicate
with via i2c. The GXP PSU driver will provide a method for the GPIO
driver with info it reads to be available to the host.

Signed-off-by: Nick Hawkins <nick.hawkins@hpe.com>
---
 drivers/hwmon/Kconfig   |  10 +
 drivers/hwmon/Makefile  |   1 +
 drivers/hwmon/gxp-psu.c | 773 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 784 insertions(+)
 create mode 100644 drivers/hwmon/gxp-psu.c

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 5b3b76477b0e..3b56690ea089 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -723,6 +723,16 @@ config SENSORS_GXP_FAN_CTRL
 	  The GXP controls fan function via the CPLD through the use of PWM
 	  registers. This driver reports status and pwm setting of the fans.
 
+config SENSORS_GXP_PSU
+	tristate "HPE GXP PSU driver"
+	depends on ARCH_HPE_GXP || COMPILE_TEST
+	depends on I2C
+	help
+	  If you say yes you will get support for GXP psu driver support. The GXP
+	  gets PSU presence and state information from the CPLD. The GXP gets PSU
+	  data via i2c. It provides a method for other drivers to call into get
+	  PSU presence information.
+
 config SENSORS_HIH6130
 	tristate "Honeywell Humidicon HIH-6130 humidity/temperature sensor"
 	depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 88712b5031c8..6c84cd52d0d3 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -84,6 +84,7 @@ obj-$(CONFIG_SENSORS_GL520SM)	+= gl520sm.o
 obj-$(CONFIG_SENSORS_GSC)	+= gsc-hwmon.o
 obj-$(CONFIG_SENSORS_GPIO_FAN)	+= gpio-fan.o
 obj-$(CONFIG_SENSORS_GXP_FAN_CTRL) += gxp-fan-ctrl.o
+obj-$(CONFIG_SENSORS_GXP_PSU)	+= gxp-psu.o
 obj-$(CONFIG_SENSORS_HIH6130)	+= hih6130.o
 obj-$(CONFIG_SENSORS_ULTRA45)	+= ultra45_env.o
 obj-$(CONFIG_SENSORS_I5500)	+= i5500_temp.o
diff --git a/drivers/hwmon/gxp-psu.c b/drivers/hwmon/gxp-psu.c
new file mode 100644
index 000000000000..e4217200c34b
--- /dev/null
+++ b/drivers/hwmon/gxp-psu.c
@@ -0,0 +1,773 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (C) 2023 Hewlett-Packard Enterpise Development Company, L.P. */
+
+#include <linux/err.h>
+#include <linux/debugfs.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/regmap.h>
+
+#define READ_REG_CMD		0x00
+#define READ_FRU_CMD		0x22
+#define REG_IN_VOL		0x10
+#define REG_IN_CUR		0x11
+#define REG_IN_PWR		0x12
+#define REG_OUT_VOL		0x20
+#define REG_OUT_CUR		0x21
+#define REG_OUT_PWR		0x22
+#define REG_FAN_SPEED		0x40
+#define REG_INLET_TEMP		0x42
+#define MAX_PSU			0x08
+#define INPUT_CHAN 0
+
+#define L_IN_POWER		"pin1"
+#define L_OUT_POWER		"pout1"
+#define L_IN_IN			"vin"
+#define L_OUT_IN		"vout1"
+#define L_FAN			"fan1"
+#define L_IN_CURR		"iin"
+#define L_OUT_CURR		"iout1"
+#define L_TEMP			"temp1"
+
+static void __iomem *pl_psu;
+
+struct gxp_psu_drvdata {
+	struct i2c_client *client;
+	u16 input_power;
+	u16 input_voltage;
+	u16 input_current;
+	u16 output_power;
+	u16 output_voltage;
+	u16 output_current;
+	s16 inlet_temp;
+	u16 fan_speed;
+	u8 id;
+	struct dentry *debugfs;
+	u8 spare_part[10];
+	u8 product_name[26];
+	u8 serial_number[14];
+	u8 product_manufacturer[3];
+	bool present; /* psu can be physically removed */
+	struct mutex update_lock;
+	struct device *hwmon_dev;
+};
+
+static u8 psucount;
+struct gxp_psu_drvdata *psus[MAX_PSU] = { NULL };
+
+u8 get_psu_inst(void)
+{
+	if (!pl_psu)
+		return 0;
+
+	return readb(pl_psu);
+}
+EXPORT_SYMBOL(get_psu_inst);
+
+u8 get_psu_ac(void)
+{
+	if (!pl_psu)
+		return 0;
+
+	return readb(pl_psu + 0x02);
+}
+EXPORT_SYMBOL(get_psu_ac);
+
+u8 get_psu_dc(void)
+{
+	if (!pl_psu)
+		return 0;
+
+	return readb(pl_psu + 0x03);
+}
+EXPORT_SYMBOL(get_psu_dc);
+
+void update_presence(u8 id)
+{
+	unsigned int i;
+	unsigned long temp = (unsigned long)readb(pl_psu);
+
+	for_each_set_bit(i, &temp, 8) {
+		if (i == id)
+			psus[id]->present = true;
+	}
+
+	temp = ~temp;
+	for_each_set_bit(i, &temp, 8) {
+		if (i == id)
+			psus[id]->present = false;
+	}
+}
+
+static unsigned char cal_checksum(unsigned char *buf, unsigned long size)
+{
+	unsigned char sum = 0;
+
+	while (size > 0) {
+		sum += (*(buf++));
+		size--;
+	}
+	return ((~sum) + 1);
+}
+
+static unsigned char valid_checksum(unsigned char *buf, unsigned long size)
+{
+	unsigned char sum = 0;
+
+	while (size > 0) {
+		sum += (*(buf++));
+		size--;
+	}
+	return sum;
+}
+
+static int psu_read_fru(struct gxp_psu_drvdata *drvdata,
+			u8 offset, u8 length, u8 *value)
+{
+	struct i2c_client *client = drvdata->client;
+	unsigned char buf_tx[4] = {(client->addr << 1), READ_FRU_CMD, offset, length};
+	unsigned char tx[4] = {0};
+	unsigned char chksum = cal_checksum(buf_tx, 4);
+	int ret = 0;
+	struct i2c_msg msgs[2] = {0};
+
+	update_presence(drvdata->id);
+
+	value[0] = '\0';
+
+	if (!drvdata->present)
+		return -EOPNOTSUPP;
+
+	tx[0] = READ_FRU_CMD;
+	tx[1] = offset;
+	tx[2] = length;
+	tx[3] = chksum;
+	msgs[0].addr = client->addr;
+	msgs[0].flags = 0;
+	msgs[0].buf = tx;
+	msgs[0].len = 4;
+	msgs[1].addr = client->addr;
+	msgs[1].flags = I2C_M_RD;
+	msgs[1].buf = value;
+	msgs[1].len = length;
+
+	mutex_lock(&drvdata->update_lock);
+	ret = i2c_transfer(client->adapter, msgs, 2);
+	mutex_unlock(&drvdata->update_lock);
+	if (ret < 0) {
+		dev_err(&client->dev,
+			"gxppsu_i2c_tx_fail addr:0x%x offest:0x%x length:0x%x chk:0x%x ret:0x%x\n",
+			client->addr, offset, length, chksum, ret);
+		return ret;
+	}
+
+	return ret;
+}
+
+static int psu_read_reg_word(struct gxp_psu_drvdata *drvdata,
+			     u8 reg, u16 *value)
+{
+	struct i2c_client *client = drvdata->client;
+	unsigned char buf_tx[3] = {(client->addr << 1), READ_REG_CMD, reg};
+	unsigned char buf_rx[3] = {0};
+	unsigned char tx[3] = {0};
+	unsigned char rx[3] = {0};
+	unsigned char chksum = cal_checksum(buf_tx, 3);
+	struct i2c_msg msgs[2] = {0};
+	int ret = 0;
+
+	tx[0] = 0;
+	tx[1] = reg;
+	tx[2] = chksum;
+
+	msgs[0].addr = client->addr;
+	msgs[0].flags = 0;
+	msgs[0].buf = tx;
+	msgs[0].len = 3;
+	msgs[1].addr = client->addr;
+	msgs[1].flags = I2C_M_RD;
+	msgs[1].buf = rx;
+	msgs[1].len = 3;
+	mutex_lock(&drvdata->update_lock);
+	ret = i2c_transfer(client->adapter, msgs, 2);
+	mutex_unlock(&drvdata->update_lock);
+	if (ret < 0) {
+		dev_err(&client->dev,
+			"gxppsu_i2c_tx_fail addr:0x%x reg:0x%x chk:0x%x ret:0x%x\n",
+			client->addr, reg, chksum, ret);
+		return ret;
+	}
+
+	buf_rx[0] = rx[0];
+	buf_rx[1] = rx[1];
+	buf_rx[2] = rx[2];
+	if (valid_checksum(buf_rx, 3) != 0) {
+		dev_err(&client->dev,
+			"gxppsu_checksum_fail addr:0x%x reg:0x%x, data:%x %x %x\n",
+			client->addr, reg, rx[0], rx[1], rx[2]);
+		return -EAGAIN;
+	}
+
+	*value = rx[0] + (rx[1] << 8);
+
+	return ret;
+}
+
+static int gxppsu_update_client(struct device *dev, u8 reg)
+{
+	struct gxp_psu_drvdata *drvdata = dev_get_drvdata(dev);
+	int ret = 0;
+
+	update_presence(drvdata->id);
+
+	if (!drvdata->present)
+		return -EOPNOTSUPP;
+
+	switch (reg) {
+	case REG_IN_PWR:
+		ret = psu_read_reg_word(drvdata, REG_IN_PWR,
+					&drvdata->input_power);
+		break;
+	case REG_IN_VOL:
+		ret = psu_read_reg_word(drvdata, REG_IN_VOL,
+					&drvdata->input_voltage);
+		break;
+	case REG_IN_CUR:
+		ret = psu_read_reg_word(drvdata, REG_IN_CUR,
+					&drvdata->input_current);
+		break;
+	case REG_OUT_PWR:
+		ret = psu_read_reg_word(drvdata, REG_OUT_PWR,
+					&drvdata->output_power);
+		break;
+	case REG_OUT_VOL:
+		ret = psu_read_reg_word(drvdata, REG_OUT_VOL,
+					&drvdata->output_voltage);
+		break;
+	case REG_OUT_CUR:
+		ret = psu_read_reg_word(drvdata, REG_OUT_CUR,
+					&drvdata->output_current);
+		break;
+	case REG_INLET_TEMP:
+		ret = psu_read_reg_word(drvdata, REG_INLET_TEMP,
+					&drvdata->inlet_temp);
+		break;
+	case REG_FAN_SPEED:
+		ret = psu_read_reg_word(drvdata, REG_FAN_SPEED,
+					&drvdata->fan_speed);
+		break;
+	default:
+		dev_err(&drvdata->client->dev, "gxppsu_error_reg 0x%x\n", reg);
+		return -EOPNOTSUPP;
+	}
+
+	return ret;
+}
+
+static int gxp_psu_get_power_input(struct device *dev, u32 attr, int channel,
+				   long *val)
+{
+	struct gxp_psu_drvdata *drvdata = dev_get_drvdata(dev);
+	int ret = 0;
+	u8 reg;
+
+	if (channel == INPUT_CHAN)
+		reg = REG_IN_PWR;
+	else
+		reg = REG_OUT_PWR;
+
+	ret = gxppsu_update_client(dev, reg);
+	if (ret < 0)
+		return ret;
+
+	if (channel == INPUT_CHAN)
+		*val = drvdata->input_power;
+	else
+		*val = drvdata->output_power;
+
+	return 0;
+}
+
+static int gxp_psu_get_in_input(struct device *dev, u32 attr, int channel,
+				long *val)
+{
+	struct gxp_psu_drvdata *drvdata = dev_get_drvdata(dev);
+	int ret = 0;
+	u8 reg;
+
+	if (channel == INPUT_CHAN)
+		reg = REG_IN_VOL;
+	else
+		reg = REG_OUT_VOL;
+
+	ret = gxppsu_update_client(dev, reg);
+	if (ret < 0)
+		return ret;
+
+	if (channel == INPUT_CHAN)
+		*val = drvdata->input_voltage;
+	else
+		*val = drvdata->output_voltage;
+
+	return 0;
+}
+
+static int gxp_psu_get_curr_input(struct device *dev, u32 attr, int channel,
+				  long *val)
+{
+	struct gxp_psu_drvdata *drvdata = dev_get_drvdata(dev);
+	int ret = 0;
+	u8 reg;
+
+	if (channel == INPUT_CHAN)
+		reg = REG_IN_CUR;
+	else
+		reg = REG_OUT_CUR;
+
+	ret = gxppsu_update_client(dev, reg);
+
+	if (ret < 0)
+		return ret;
+
+	if (channel == INPUT_CHAN)
+		*val = drvdata->input_current;
+	else
+		*val = drvdata->output_current;
+
+	return 0;
+}
+
+static int gxp_psu_get_temp_input(struct device *dev, u32 attr, int channel,
+				  long *val)
+{
+	struct gxp_psu_drvdata *drvdata = dev_get_drvdata(dev);
+	int ret = 0;
+	u8 reg = REG_INLET_TEMP;
+
+	ret = gxppsu_update_client(dev, reg);
+	if (ret < 0)
+		return ret;
+
+	*val = drvdata->inlet_temp;
+
+	return 0;
+};
+
+static int gxp_psu_get_fan_input(struct device *dev, u32 attr, int channel,
+				 long *val)
+{
+	struct gxp_psu_drvdata *drvdata = dev_get_drvdata(dev);
+	int ret = 0;
+	u8 reg = REG_FAN_SPEED;
+
+	ret = gxppsu_update_client(dev, reg);
+	if (ret < 0)
+		return ret;
+
+	*val = drvdata->fan_speed;
+
+	return 0;
+}
+
+void swapbytes(void *input, size_t len)
+{
+	unsigned int i;
+	unsigned char *in = (unsigned char *)input, tmp;
+
+	for (i = 0; i < len / 2; i++) {
+		tmp = *(in + i);
+		*(in + i) = *(in + len - i - 1);
+		*(in + len - i - 1) = tmp;
+	}
+}
+
+static const struct hwmon_channel_info *gxp_psu_info[] = {
+	HWMON_CHANNEL_INFO(power,
+			   HWMON_P_INPUT | HWMON_P_LABEL,
+			   HWMON_P_INPUT | HWMON_P_LABEL),
+	HWMON_CHANNEL_INFO(in,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL),
+	HWMON_CHANNEL_INFO(fan,
+			   HWMON_F_INPUT | HWMON_F_LABEL),
+	HWMON_CHANNEL_INFO(curr,
+			   HWMON_C_INPUT | HWMON_C_LABEL,
+			   HWMON_C_INPUT | HWMON_C_LABEL),
+	HWMON_CHANNEL_INFO(temp,
+			   HWMON_T_INPUT | HWMON_T_LABEL),
+	NULL
+};
+
+static umode_t gxp_psu_is_visible(const void *_data, enum hwmon_sensor_types type,
+				  u32 attr, int channel)
+{
+	umode_t mode = 0;
+
+	switch (type) {
+	case hwmon_power:
+		switch (attr) {
+		case hwmon_power_input:
+		case hwmon_power_label:
+			mode = 0444;
+			break;
+		default:
+			break;
+		}
+	break;
+	case hwmon_in:
+		switch (attr) {
+		case hwmon_in_input:
+		case hwmon_in_label:
+			mode = 0444;
+			break;
+		default:
+			break;
+		}
+		break;
+	case hwmon_fan:
+		switch (attr) {
+		case hwmon_fan_input:
+		case hwmon_fan_label:
+			mode = 0444;
+			break;
+		default:
+			break;
+		}
+		break;
+	case hwmon_curr:
+		switch (attr) {
+		case hwmon_curr_input:
+		case hwmon_curr_label:
+			mode = 0444;
+			break;
+		default:
+			break;
+		}
+		break;
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_input:
+		case hwmon_temp_label:
+			mode = 0444;
+			break;
+		default:
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+
+	return mode;
+}
+
+static int gxp_psu_read(struct device *dev, enum hwmon_sensor_types type,
+			u32 attr, int channel, long *val)
+{
+	switch (type) {
+	case hwmon_power:
+		switch (attr) {
+		case hwmon_power_input:
+			return gxp_psu_get_power_input(dev, attr, channel,
+							       val);
+		default:
+			break;
+		}
+		break;
+	case hwmon_in:
+		switch (attr) {
+		case hwmon_in_input:
+			return gxp_psu_get_in_input(dev, attr, channel,
+							    val);
+		default:
+			break;
+		}
+		break;
+	case hwmon_fan:
+		switch (attr) {
+		case hwmon_fan_input:
+			return gxp_psu_get_fan_input(dev, attr, channel,
+							     val);
+		default:
+			break;
+		}
+		break;
+	case hwmon_curr:
+		switch (attr) {
+		case hwmon_curr_input:
+			return gxp_psu_get_curr_input(dev, attr, channel,
+						val);
+		default:
+			break;
+		}
+		break;
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_input:
+			return gxp_psu_get_temp_input(dev, attr, channel,
+						      val);
+		default:
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+	return -EOPNOTSUPP;
+}
+
+static int gxp_psu_read_string(struct device *dev, enum hwmon_sensor_types type,
+			       u32 attr, int channel, const char **str)
+{
+	switch (type) {
+	case hwmon_power:
+		switch (attr) {
+		case hwmon_power_label:
+			*str = channel ? L_OUT_POWER : L_IN_POWER;
+			return 0;
+		default:
+			break;
+		}
+	case hwmon_in:
+		switch (attr) {
+		case hwmon_in_label:
+			*str = channel ? L_OUT_IN : L_IN_IN;
+			return 0;
+		default:
+			break;
+		}
+	case hwmon_fan:
+		switch (attr) {
+		case hwmon_fan_label:
+			*str = L_FAN;
+			return 0;
+		default:
+			break;
+		}
+	case hwmon_curr:
+		switch (attr) {
+		case hwmon_curr_label:
+			*str = channel ? L_OUT_CURR : L_IN_CURR;
+			return 0;
+		default:
+			break;
+		}
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_label:
+			*str = L_TEMP;
+			return 0;
+		default:
+			break;
+		}
+	default:
+		break;
+	}
+	return -EOPNOTSUPP;
+}
+
+static const struct hwmon_ops gxp_psu_ops = {
+	.is_visible = gxp_psu_is_visible,
+	.read = gxp_psu_read,
+	.read_string = gxp_psu_read_string,
+};
+
+static const struct hwmon_chip_info gxp_psu_chip_info = {
+	.ops = &gxp_psu_ops,
+	.info = gxp_psu_info,
+};
+
+#ifdef CONFIG_DEBUG_FS
+
+static int serial_number_show(struct seq_file *seqf, void *unused)
+{
+	struct gxp_psu_drvdata *drvdata = seqf->private;
+	int ret = 0;
+
+	ret = psu_read_fru(drvdata, 91, 14, &drvdata->serial_number[0]);
+	if (ret < 0) {
+		dev_err(&drvdata->client->dev, "Unknown product serial number %d", ret);
+		seq_puts(seqf, "unknown\n");
+		return 0;
+	}
+
+	seq_printf(seqf, "%s\n", drvdata->serial_number);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(serial_number);
+
+static int manufacturer_show(struct seq_file *seqf, void *unused)
+{
+	struct gxp_psu_drvdata *drvdata = seqf->private;
+	int ret = 0;
+
+	ret = psu_read_fru(drvdata, 197, 3, &drvdata->product_manufacturer[0]);
+	if (ret < 0) {
+		dev_err(&drvdata->client->dev, "Unknown product manufacturer %d", ret);
+		seq_puts(seqf, "unknown\n");
+		return 0;
+	}
+
+	swapbytes(&drvdata->product_manufacturer[0], 3);
+	seq_printf(seqf, "%s\n", drvdata->product_manufacturer);
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(manufacturer);
+
+static int product_name_show(struct seq_file *seqf, void *unused)
+{
+	struct gxp_psu_drvdata *drvdata = seqf->private;
+	int ret = 0;
+
+	ret = psu_read_fru(drvdata, 50, 26, &drvdata->product_name[0]);
+	if (ret < 0) {
+		dev_err(&drvdata->client->dev, "Unknown product name %d", ret);
+		seq_puts(seqf, "unknown\n");
+		return 0;
+	}
+
+	seq_printf(seqf, "%s\n", drvdata->product_name);
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(product_name);
+
+static int spare_show(struct seq_file *seqf, void *unused)
+{
+	struct gxp_psu_drvdata *drvdata = seqf->private;
+	int ret = 0;
+
+	ret = psu_read_fru(drvdata, 18, 10, &drvdata->spare_part[0]);
+	if (ret < 0) {
+		dev_err(&drvdata->client->dev, "Unknown product spare %d", ret);
+		seq_puts(seqf, "unknown\n");
+		return 0;
+	}
+
+	seq_printf(seqf, "%s\n", drvdata->spare_part);
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(spare);
+
+static int present_show(struct seq_file *seqf, void *unused)
+{
+	struct gxp_psu_drvdata *drvdata = seqf->private;
+
+	update_presence(drvdata->id);
+
+	if (drvdata->present)
+		seq_puts(seqf, "yes\n");
+	else
+		seq_puts(seqf, "no\n");
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(present);
+
+static void gxp_psu_debugfs_init(struct gxp_psu_drvdata *drvdata)
+{
+	char name[32];
+
+	scnprintf(name, sizeof(name), "%s_%s-%d", dev_name(drvdata->hwmon_dev),
+		  drvdata->client->name, drvdata->client->addr);
+
+	drvdata->debugfs = debugfs_create_dir(name, NULL);
+
+	debugfs_create_file("serial_number", 0444, drvdata->debugfs, drvdata, &serial_number_fops);
+
+	debugfs_create_file("manufacturer", 0444, drvdata->debugfs, drvdata, &manufacturer_fops);
+
+	debugfs_create_file("product_name", 0444, drvdata->debugfs, drvdata, &product_name_fops);
+
+	debugfs_create_file("spare", 0444, drvdata->debugfs, drvdata, &spare_fops);
+
+	debugfs_create_file("present", 0444, drvdata->debugfs, drvdata, &present_fops);
+
+	if (!debugfs_initialized())
+		dev_err(&drvdata->client->dev, "Debug FS not Init");
+}
+
+#else
+
+static void gxp_psu_debugfs_init(struct gxp_psu_drvdata *drvdata)
+{
+}
+
+#endif
+
+static int gxp_psu_probe(struct i2c_client *client)
+{
+	struct gxp_psu_drvdata *drvdata;
+	struct device *hwmon_dev;
+	struct device_node *np;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL))
+		return -EIO;
+
+	drvdata = devm_kzalloc(&client->dev, sizeof(struct gxp_psu_drvdata),
+			       GFP_KERNEL);
+	if (!drvdata)
+		return -ENOMEM;
+
+	if (!pl_psu) {
+		np = of_parse_phandle(client->dev.of_node, "hpe,sysreg", 0);
+		if (!np)
+			return -ENODEV;
+
+		pl_psu = of_iomap(np, 0);
+		if (IS_ERR(pl_psu))
+			return dev_err_probe(&client->dev, IS_ERR(pl_psu),
+					     "failed to map pl_psu");
+	}
+
+	drvdata->client = client;
+	i2c_set_clientdata(client, drvdata);
+
+	mutex_init(&drvdata->update_lock);
+	drvdata->hwmon_dev = NULL;
+	hwmon_dev = devm_hwmon_device_register_with_info(&client->dev,
+							 "hpe_gxp_psu",
+							 drvdata,
+							 &gxp_psu_chip_info,
+							 NULL);
+	if (IS_ERR(hwmon_dev))
+		return PTR_ERR(hwmon_dev);
+
+	drvdata->hwmon_dev = hwmon_dev;
+
+	drvdata->id = psucount;
+
+	psus[psucount] = drvdata;
+
+	update_presence(drvdata->id);
+
+	psucount++;
+
+	gxp_psu_debugfs_init(drvdata);
+
+	return 0;
+}
+
+static const struct of_device_id gxp_psu_of_match[] = {
+	{ .compatible = "hpe,gxp-psu" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, gxp_psu_of_match);
+
+static struct i2c_driver gxp_psu_driver = {
+	.class = I2C_CLASS_HWMON,
+	.driver = {
+		.name	= "gxp-psu",
+		.of_match_table = gxp_psu_of_match,
+	},
+	.probe_new = gxp_psu_probe,
+};
+module_i2c_driver(gxp_psu_driver);
+
+MODULE_AUTHOR("Nick Hawkins <nick.hawkins@hpe.com>");
+MODULE_DESCRIPTION("HPE GXP PSU driver");
+MODULE_LICENSE("GPL");
-- 
2.17.1