hwmon: Add On-Chip Controller (OCC) hwmon driver

The OCC is a device embedded on a POWER processor that collects and
aggregates sensor data from the processor and system. The OCC can
provide the raw sensor data as well as perform thermal and power
management on the system.

This driver provides a hwmon interface to the OCC from a service
processor (e.g. a BMC). The driver supports both POWER8 and POWER9 OCCs.
Communications with the POWER8 OCC are established over standard I2C
bus. The driver communicates with the POWER9 OCC through the FSI-based
OCC driver, which handles the lower-level communication details.

This patch lays out the structure of the OCC hwmon driver. There are two
platform drivers, one each for P8 and P9 OCCs. These are probed through
the I2C tree and the FSI-based OCC driver, respectively. The patch also
defines the first common structures and methods between the two OCC
versions.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
[groeck: Fix up SPDX license identifier]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 61 insertions, 0 deletions

diff --git a/drivers/hwmon/occ/p8_i2c.c b/drivers/hwmon/occ/p8_i2c.c
new file mode 100644
index 000000000000..4f3937dec480
--- /dev/null
+++ b/drivers/hwmon/occ/p8_i2c.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+
+#include "common.h"
+
+struct p8_i2c_occ {
+	struct occ occ;
+	struct i2c_client *client;
+};
+
+#define to_p8_i2c_occ(x)	container_of((x), struct p8_i2c_occ, occ)
+
+static int p8_i2c_occ_send_cmd(struct occ *occ, u8 *cmd)
+{
+	return -EOPNOTSUPP;
+}
+
+static int p8_i2c_occ_probe(struct i2c_client *client,
+			    const struct i2c_device_id *id)
+{
+	struct occ *occ;
+	struct p8_i2c_occ *ctx = devm_kzalloc(&client->dev, sizeof(*ctx),
+					      GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
+
+	ctx->client = client;
+	occ = &ctx->occ;
+	occ->bus_dev = &client->dev;
+	dev_set_drvdata(&client->dev, occ);
+
+	occ->poll_cmd_data = 0x10;		/* P8 OCC poll data */
+	occ->send_cmd = p8_i2c_occ_send_cmd;
+
+	return occ_setup(occ, "p8_occ");
+}
+
+static const struct of_device_id p8_i2c_occ_of_match[] = {
+	{ .compatible = "ibm,p8-occ-hwmon" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, p8_i2c_occ_of_match);
+
+static struct i2c_driver p8_i2c_occ_driver = {
+	.class = I2C_CLASS_HWMON,
+	.driver = {
+		.name = "occ-hwmon",
+		.of_match_table = p8_i2c_occ_of_match,
+	},
+	.probe = p8_i2c_occ_probe,
+};
+
+module_i2c_driver(p8_i2c_occ_driver);
+
+MODULE_AUTHOR("Eddie James <eajames@linux.ibm.com>");
+MODULE_DESCRIPTION("BMC P8 OCC hwmon driver");
+MODULE_LICENSE("GPL");