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    Subject[PATCH v5 4/6] fsi: Add I2C Responder SCOM driver
    Date
    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>
    ---
    drivers/fsi/Kconfig | 12 +++
    drivers/fsi/Makefile | 1 +
    drivers/fsi/i2cr-scom.c | 158 ++++++++++++++++++++++++++++++++++++++++
    3 files changed, 171 insertions(+)
    create mode 100644 drivers/fsi/i2cr-scom.c

    diff --git a/drivers/fsi/Kconfig b/drivers/fsi/Kconfig
    index 999be82720c5..09a8285d4bdc 100644
    --- a/drivers/fsi/Kconfig
    +++ b/drivers/fsi/Kconfig
    @@ -71,6 +71,18 @@ config FSI_MASTER_I2CR
    that translates I2C commands to CFAM or SCOM operations, effectively
    implementing an FSI master and bus.

    +if FSI_MASTER_I2CR
    +
    +config I2CR_SCOM
    + tristate "IBM I2C Responder SCOM driver"
    + default y
    + 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
    +
    config FSI_SCOM
    tristate "SCOM FSI client device driver"
    help
    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..7e1c7b93c32f
    --- /dev/null
    +++ b/drivers/fsi/i2cr-scom.c
    @@ -0,0 +1,158 @@
    +// 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;
    + __be64 data_be;
    + u64 data;
    + int ret;
    +
    + if (len != sizeof(data))
    + return -EINVAL;
    +
    + ret = fsi_master_i2cr_read(scom->i2cr, (u32)*offset, &data_be, sizeof(data_be));
    + if (ret)
    + return ret;
    +
    + data = be64_to_cpu(data_be);
    + 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;
    + __be64 data_be;
    + u64 data;
    + int ret;
    +
    + if (len != sizeof(data))
    + return -EINVAL;
    +
    + ret = copy_from_user(&data, buf, len);
    + if (ret)
    + return ret;
    +
    + data_be = cpu_to_be64(data);
    + ret = fsi_master_i2cr_write(scom->i2cr, (u32)*offset, &data_be, sizeof(data_be));
    + 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
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