[PATCH v7 4/7] fsi: Add I2C Responder SCOM driver

Eddie James
2023-03-03T17:05:01Z

The I2CR has the capability to directly perform SCOM operations,
circumventing the need to drive the FSI2PIB engine. Add a new
driver to perform SCOM operations through the I2CR.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
---
Changes since v6:
- Update SCOM driver with newer interfaces and drop BE conversion

drivers/fsi/Kconfig | 8 +++
drivers/fsi/Makefile | 1 +
drivers/fsi/i2cr-scom.c | 154 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 163 insertions(+)
create mode 100644 drivers/fsi/i2cr-scom.c

diff --git a/drivers/fsi/Kconfig b/drivers/fsi/Kconfig
index 999be82720c5..79a31593618a 100644
--- a/drivers/fsi/Kconfig
+++ b/drivers/fsi/Kconfig
@@ -94,4 +94,12 @@ config FSI_OCC
provide the raw sensor data as well as perform thermal and power
management on the system.

+config I2CR_SCOM
+ tristate "IBM I2C Responder SCOM driver"
+ depends on FSI_MASTER_I2CR
+ help
+ This option enables an I2C Responder based SCOM device driver. The
+ I2CR has the capability to directly perform SCOM operations instead
+ of using the FSI2PIB engine.
+
endif
diff --git a/drivers/fsi/Makefile b/drivers/fsi/Makefile
index 34dbaa1c452e..5550aa15e0b1 100644
--- a/drivers/fsi/Makefile
+++ b/drivers/fsi/Makefile
@@ -9,3 +9,4 @@ obj-$(CONFIG_FSI_MASTER_AST_CF) += fsi-master-ast-cf.o
obj-$(CONFIG_FSI_SCOM) += fsi-scom.o
obj-$(CONFIG_FSI_SBEFIFO) += fsi-sbefifo.o
obj-$(CONFIG_FSI_OCC) += fsi-occ.o
+obj-$(CONFIG_I2CR_SCOM) += i2cr-scom.o
diff --git a/drivers/fsi/i2cr-scom.c b/drivers/fsi/i2cr-scom.c
new file mode 100644
index 000000000000..63b548bdef3e
--- /dev/null
+++ b/drivers/fsi/i2cr-scom.c
@@ -0,0 +1,154 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) IBM Corporation 2023 */
+
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <linux/fsi.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+
+#include "fsi-master-i2cr.h"
+#include "fsi-slave.h"
+
+struct i2cr_scom {
+ struct device dev;
+ struct cdev cdev;
+ struct fsi_master_i2cr *i2cr;
+};
+
+static loff_t i2cr_scom_llseek(struct file *file, loff_t offset, int whence)
+{
+ switch (whence) {
+ case SEEK_CUR:
+ break;
+ case SEEK_SET:
+ file->f_pos = offset;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return offset;
+}
+
+static ssize_t i2cr_scom_read(struct file *filep, char __user *buf, size_t len, loff_t *offset)
+{
+ struct i2cr_scom *scom = filep->private_data;
+ u64 data;
+ int ret;
+
+ if (len != sizeof(data))
+ return -EINVAL;
+
+ ret = fsi_master_i2cr_read(scom->i2cr, (u32)*offset, &data);
+ if (ret)
+ return ret;
+
+ ret = copy_to_user(buf, &data, len);
+ if (ret)
+ return ret;
+
+ return len;
+}
+
+static ssize_t i2cr_scom_write(struct file *filep, const char __user *buf, size_t len,
+ loff_t *offset)
+{
+ struct i2cr_scom *scom = filep->private_data;
+ u64 data;
+ int ret;
+
+ if (len != sizeof(data))
+ return -EINVAL;
+
+ ret = copy_from_user(&data, buf, len);
+ if (ret)
+ return ret;
+
+ ret = fsi_master_i2cr_write(scom->i2cr, (u32)*offset, data);
+ if (ret)
+ return ret;
+
+ return len;
+}
+
+static const struct file_operations i2cr_scom_fops = {
+ .owner = THIS_MODULE,
+ .open = simple_open,
+ .llseek = i2cr_scom_llseek,
+ .read = i2cr_scom_read,
+ .write = i2cr_scom_write,
+};
+
+static int i2cr_scom_probe(struct device *dev)
+{
+ struct fsi_device *fsi_dev = to_fsi_dev(dev);
+ struct i2cr_scom *scom;
+ int didx;
+ int ret;
+
+ if (!(fsi_dev->slave->master->flags & FSI_MASTER_FLAG_I2CR))
+ return -ENODEV;
+
+ scom = devm_kzalloc(dev, sizeof(*scom), GFP_KERNEL);
+ if (!scom)
+ return -ENOMEM;
+
+ scom->i2cr = to_fsi_master_i2cr(fsi_dev->slave->master);
+ dev_set_drvdata(dev, scom);
+
+ scom->dev.type = &fsi_cdev_type;
+ scom->dev.parent = dev;
+ device_initialize(&scom->dev);
+
+ ret = fsi_get_new_minor(fsi_dev, fsi_dev_scom, &scom->dev.devt, &didx);
+ if (ret)
+ return ret;
+
+ dev_set_name(&scom->dev, "scom%d", didx);
+ cdev_init(&scom->cdev, &i2cr_scom_fops);
+ ret = cdev_device_add(&scom->cdev, &scom->dev);
+ if (ret)
+ fsi_free_minor(scom->dev.devt);
+
+ return ret;
+}
+
+static int i2cr_scom_remove(struct device *dev)
+{
+ struct i2cr_scom *scom = dev_get_drvdata(dev);
+
+ cdev_device_del(&scom->cdev, &scom->dev);
+ fsi_free_minor(scom->dev.devt);
+
+ return 0;
+}
+
+static const struct of_device_id i2cr_scom_of_ids[] = {
+ { .compatible = "ibm,i2cr-scom" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, i2cr_scom_of_ids);
+
+static const struct fsi_device_id i2cr_scom_ids[] = {
+ { 0x5, FSI_VERSION_ANY },
+ { }
+};
+
+static struct fsi_driver i2cr_scom_driver = {
+ .id_table = i2cr_scom_ids,
+ .drv = {
+ .name = "i2cr_scom",
+ .bus = &fsi_bus_type,
+ .of_match_table = i2cr_scom_of_ids,
+ .probe = i2cr_scom_probe,
+ .remove = i2cr_scom_remove,
+ }
+};
+
+module_fsi_driver(i2cr_scom_driver);
+
+MODULE_AUTHOR("Eddie James <eajames@linux.ibm.com>");
+MODULE_DESCRIPTION("IBM I2C Responder SCOM driver");
+MODULE_LICENSE("GPL");
--
2.31.1