[PATCH linux v6 18/18] drivers/fsi: Add SCOM FSI client device driver

Christopher Bostic christopher.lee.bostic at gmail.com
Tue Nov 15 04:13:55 AEDT 2016


On Sun, Nov 13, 2016 at 5:44 PM, Alistair Popple <alistair at popple.id.au> wrote:
> Hi Chris,
>
> Is there a similar device driver for the CFAM/FSI that I missed? That is will
> there be a chardev for read/writing FSI addresses directly (ie. a chardev to
> call fsi_device_read/write)? Probably not critical for an initial release but
> we will need one at some point as I'm pretty sure the cronus server for
> example has get/putcfam commands as some registers aren't available via SCOM.
>
> Regards,
>
> Alistair
>

Hi Alistair,

No there isn't a driver like you describe in the set as it is now.  I
agree that would be important to have for general bringup debug.
Once this set is accepted I'll add that.

Thanks

> On Sun, 30 Oct 2016 05:09:20 PM christopher.lee.bostic at gmail.com wrote:
>> From: Chris Bostic <cbostic at us.ibm.com>
>>
>> Create a simple SCOM engine device driver that reads and writes
>> across an FSI bus.
>>
>> Signed-off-by: Chris Bostic <cbostic at us.ibm.com>
>>
>> ---
>>
>> V4 - Add put_scom and get_scom operations
>>
>> V5 - Add character device registration and fill in read/write
>>      syscalls.
>>
>> V6 - Add multi scom engine support. Add list of devices.
>>      Use file private data to store and hand off scom structures.
>>
>>    - Add lseek, open, close
>>
>>    - Remove data/address structure to pass from user space to
>>      kernel.  Use offset provided by read/write and pass data
>>
>>    - Added list setup in init and so did not add the macro
>>      module_fsi_driver
>>
>>    - Global structs made static where possible.
>>
>>    - Change from char dev to use misc device api as shown
>>      in examples from Jeremy Kere.
>> ---
>>  drivers/fsi/Kconfig    |   6 ++
>>  drivers/fsi/Makefile   |   1 +
>>  drivers/fsi/fsi-scom.c | 238
> +++++++++++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 245 insertions(+)
>>  create mode 100644 drivers/fsi/fsi-scom.c
>>
>> diff --git a/drivers/fsi/Kconfig b/drivers/fsi/Kconfig
>> index b21fe3c..1fa9bc0 100644
>> --- a/drivers/fsi/Kconfig
>> +++ b/drivers/fsi/Kconfig
>> @@ -23,6 +23,12 @@ config FSI_MASTER_GPIO
>>       depends on FSI
>>       ---help---
>>       This option enables a FSI master driver using GPIO lines.
>> +
>> +config FSI_SCOM
>> +     tristate "SCOM FSI client"
>> +     depends on FSI
>> +     ---help---
>> +     This option enables the SCOM FSI client device driver.
>>  endif
>>
>>  endmenu
>> diff --git a/drivers/fsi/Makefile b/drivers/fsi/Makefile
>> index 2021ce5..3e31d9a 100644
>> --- a/drivers/fsi/Makefile
>> +++ b/drivers/fsi/Makefile
>> @@ -2,3 +2,4 @@
>>  obj-$(CONFIG_FSI) += fsi-core.o
>>  obj-$(CONFIG_FSI_MASTER_FAKE) += fsi-master-fake.o
>>  obj-$(CONFIG_FSI_MASTER_GPIO) += fsi-master-gpio.o
>> +obj-$(CONFIG_FSI_SCOM) += fsi-scom.o
>> diff --git a/drivers/fsi/fsi-scom.c b/drivers/fsi/fsi-scom.c
>> new file mode 100644
>> index 0000000..27be082
>> --- /dev/null
>> +++ b/drivers/fsi/fsi-scom.c
>> @@ -0,0 +1,238 @@
>> +/*
>> + * SCOM FSI Client device driver
>> + *
>> + * Copyright (C) IBM Corporation 2016
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERGCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + */
>> +
>> +#include <linux/fsi.h>
>> +#include <linux/module.h>
>> +#include <linux/cdev.h>
>> +#include <linux/delay.h>
>> +#include <linux/fs.h>
>> +#include <linux/uaccess.h>
>> +#include <linux/slab.h>
>> +#include <linux/miscdevice.h>
>> +#include <linux/list.h>
>> +
>> +#define FSI_ENGID_SCOM               0x5
>> +
>> +#define SCOM_FSI2PIB_DELAY   50
>> +
>> +/* SCOM engine register set */
>> +#define SCOM_DATA0_REG               0x00
>> +#define SCOM_DATA1_REG               0x04
>> +#define SCOM_CMD_REG         0x08
>> +#define SCOM_RESET_REG               0x1C
>> +
>> +#define SCOM_RESET_CMD               0x80000000
>> +#define SCOM_WRITE_CMD               0x80000000
>> +
>> +struct scom_device {
>> +     struct list_head link;
>> +     struct fsi_device *fsi_dev;
>> +     struct miscdevice mdev;
>> +     char    name[32];
>> +};
>> +
>> +#define to_scom_dev(x)               container_of((x), struct scom_device,
> mdev)
>> +
>> +static struct list_head scom_devices;
>> +static atomic_t scom_idx = ATOMIC_INIT(0);
>> +static int scom_probe(struct device *);
>> +
>> +static int put_scom(struct scom_device *scom_dev, uint64_t value,
>> +                     uint32_t addr)
>> +{
>> +     int rc;
>> +     uint32_t data = SCOM_RESET_CMD;
>> +
>> +     rc = fsi_device_write(scom_dev->fsi_dev, SCOM_RESET_REG, &data,
>> +                             sizeof(uint32_t));
>> +     if (rc)
>> +             return rc;
>> +
>> +     data = (value >> 32) & 0xffffffff;
>> +     rc = fsi_device_write(scom_dev->fsi_dev, SCOM_DATA0_REG, &data,
>> +                             sizeof(uint32_t));
>> +     if (rc)
>> +             return rc;
>> +
>> +     data = value & 0xffffffff;
>> +     rc = fsi_device_write(scom_dev->fsi_dev, SCOM_DATA1_REG, &data,
>> +                             sizeof(uint32_t));
>> +     if (rc)
>> +             return rc;
>> +
>> +     data = SCOM_WRITE_CMD | addr;
>> +     return fsi_device_write(scom_dev->fsi_dev, SCOM_CMD_REG, &data,
>> +                             sizeof(uint32_t));
>> +}
>> +
>> +static int get_scom(struct scom_device *scom_dev, uint64_t *value,
>> +                     uint32_t addr)
>> +{
>> +     uint32_t result, data;
>> +     int rc;
>> +
>> +     udelay(SCOM_FSI2PIB_DELAY);
>> +
>> +     data = addr;
>> +     rc = fsi_device_write(scom_dev->fsi_dev, SCOM_CMD_REG, &data,
>> +                             sizeof(uint32_t));
>> +     if (rc)
>> +             return rc;
>> +
>> +     rc = fsi_device_read(scom_dev->fsi_dev, SCOM_DATA0_REG, &result,
>> +                             sizeof(uint32_t));
>> +     if (rc)
>> +             return rc;
>> +
>> +     *value |= (uint64_t) result << 32;
>> +     rc = fsi_device_read(scom_dev->fsi_dev, SCOM_DATA1_REG, &result,
>> +                             sizeof(uint32_t));
>> +     if (rc)
>> +             return rc;
>> +
>> +     *value |= result;
>> +
>> +     return 0;
>> +}
>> +
>> +static loff_t scom_llseek(struct file *filep, loff_t offset, int whence)
>> +{
>> +     if (whence != 0)  /* SEEK_SET */
>> +             return -EINVAL;
>> +
>> +     filep->f_pos = offset;
>> +     return offset;
>> +}
>> +
>> +static ssize_t scom_read(struct file *filep, char __user *buf, size_t len,
>> +                     loff_t *offset)
>> +{
>> +     int rc = 0;
>> +     struct miscdevice *mdev =
>> +                             (struct miscdevice *)filep->private_data;
>> +     struct scom_device *scom = to_scom_dev(mdev);
>> +     struct device *dev = &scom->fsi_dev->dev;
>> +     uint64_t val;
>> +
>> +     if (len != sizeof(uint64_t))
>> +             return -EINVAL;
>> +
>> +     rc = get_scom(scom, &val, *offset);
>> +     if (rc) {
>> +             dev_dbg(dev, "get_scom fail:%d\n", rc);
>> +             return rc;
>> +     }
>> +
>> +     rc = copy_to_user(buf, &val, len);
>> +     if (rc)
>> +             dev_dbg(dev, "copy to user failed:%d\n", rc);
>> +
>> +     return rc ? rc : len;
>> +}
>> +
>> +static ssize_t scom_write(struct file *filep, const char __user *buf,
>> +                     size_t len, loff_t *offset)
>> +{
>> +     int rc = 0;
>> +     struct miscdevice *mdev =
>> +                             (struct miscdevice *)filep->private_data;
>> +     struct scom_device *scom = to_scom_dev(mdev);
>> +     struct device *dev = &scom->fsi_dev->dev;
>> +     uint64_t val;
>> +
>> +     if (len != sizeof(uint64_t))
>> +             return -EINVAL;
>> +
>> +     rc = copy_from_user(&val, buf, len);
>> +     if (rc) {
>> +             dev_dbg(dev, "copy from user failed:%d\n", rc);
>> +             return -EINVAL;
>> +     }
>> +
>> +     rc = put_scom(scom, val, *offset);
>> +     if (rc)
>> +             dev_dbg(dev, "put_scom failed with:%d\n", rc);
>> +
>> +
>> +     return rc ? rc : len;
>> +}
>> +
>> +static const struct file_operations scom_fops = {
>> +     .owner  = THIS_MODULE,
>> +     .llseek = scom_llseek,
>> +     .read   = scom_read,
>> +     .write  = scom_write,
>> +};
>> +
>> +static int scom_probe(struct device *dev)
>> +{
>> +     struct fsi_device *fsi_dev = to_fsi_dev(dev);
>> +     struct scom_device *scom = NULL;
>> +
>> +     scom = devm_kzalloc(dev, sizeof(*scom), GFP_KERNEL);
>> +     if (!scom)
>> +             return -ENOMEM;
>> +
>> +     snprintf(scom->name, sizeof(scom->name),
>> +                     "scom%d", atomic_inc_return(&scom_idx));
>> +     scom->fsi_dev = fsi_dev;
>> +     scom->mdev.minor = MISC_DYNAMIC_MINOR;
>> +     scom->mdev.fops = &scom_fops;
>> +     scom->mdev.name = scom->name;
>> +     scom->mdev.parent = dev;
>> +     list_add(&scom->link, &scom_devices);
>> +
>> +     return misc_register(&scom->mdev);
>> +}
>> +
>> +static struct fsi_device_id scom_ids[] = {
>> +     {
>> +             .engine_type = FSI_ENGID_SCOM,
>> +             .version = FSI_VERSION_ANY,
>> +     },
>> +     { 0 }
>> +};
>> +
>> +static struct fsi_driver scom_drv = {
>> +     .id_table = scom_ids,
>> +     .drv = {
>> +             .name = "scom",
>> +             .bus = &fsi_bus_type,
>> +             .probe = scom_probe,
>> +     }
>> +};
>> +
>> +static int scom_init(void)
>> +{
>> +     INIT_LIST_HEAD(&scom_devices);
>> +     return fsi_driver_register(&scom_drv);
>> +}
>> +
>> +static void scom_exit(void)
>> +{
>> +     struct list_head *pos;
>> +     struct scom_device *scom = NULL;
>> +
>> +     list_for_each(pos, &scom_devices) {
>> +             scom = list_entry(pos, struct scom_device, link);
>> +             misc_deregister(&scom->mdev);
>> +             devm_kfree(&scom->fsi_dev->dev, scom);
>> +     }
>> +     fsi_driver_unregister(&scom_drv);
>> +}
>> +
>> +module_init(scom_init);
>> +module_exit(scom_exit);
>> +MODULE_LICENSE("GPL");
>>
>


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