by Rob Herring (Arm)

[permalink] [raw]

Subject: Re: [PATCH 14/14] fsi: Add I2C Responder SCOM driver

On Mon, Jun 12, 2023 at 02:56:57PM -0500, Eddie James wrote:
> 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 <[email protected]>
> ---
> 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..cb7e02213032
> --- /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 (!is_fsi_master_i2cr(fsi_dev->slave->master))
> + 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" },

This is not documented. Please add a binding.

Rob