fsi: scom: Major overhaul

This was too hard to split ... this adds a number of features
to the SCOM user interface:

 - Support for indirect SCOMs

 - read()/write() interface now handle errors and retries

 - New ioctl() "raw" interface for use by debuggers

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: Eddie James <eajames@linux.vnet.ibm.com>
Reviewed-by: Alistair Popple <alistair@popple.id.au>
This commit is contained in:
Benjamin Herrenschmidt 2018-06-12 15:19:11 +10:00
parent f143304442
commit 6b293258cd
2 changed files with 452 additions and 30 deletions

View File

@ -24,6 +24,8 @@
#include <linux/list.h>
#include <linux/idr.h>
#include <uapi/linux/fsi.h>
#define FSI_ENGID_SCOM 0x5
/* SCOM engine register set */
@ -41,14 +43,36 @@
/* Status register bits */
#define SCOM_STATUS_ERR_SUMMARY 0x80000000
#define SCOM_STATUS_PROTECTION 0x01000000
#define SCOM_STATUS_PARITY 0x04000000
#define SCOM_STATUS_PIB_ABORT 0x00100000
#define SCOM_STATUS_PIB_RESP_MASK 0x00007000
#define SCOM_STATUS_PIB_RESP_SHIFT 12
#define SCOM_STATUS_ANY_ERR (SCOM_STATUS_ERR_SUMMARY | \
SCOM_STATUS_PROTECTION | \
SCOM_STATUS_PARITY | \
SCOM_STATUS_PIB_ABORT | \
SCOM_STATUS_PIB_RESP_MASK)
/* SCOM address encodings */
#define XSCOM_ADDR_IND_FLAG BIT_ULL(63)
#define XSCOM_ADDR_INF_FORM1 BIT_ULL(60)
/* SCOM indirect stuff */
#define XSCOM_ADDR_DIRECT_PART 0x7fffffffull
#define XSCOM_ADDR_INDIRECT_PART 0x000fffff00000000ull
#define XSCOM_DATA_IND_READ BIT_ULL(63)
#define XSCOM_DATA_IND_COMPLETE BIT_ULL(31)
#define XSCOM_DATA_IND_ERR_MASK 0x70000000ull
#define XSCOM_DATA_IND_ERR_SHIFT 28
#define XSCOM_DATA_IND_DATA 0x0000ffffull
#define XSCOM_DATA_IND_FORM1_DATA 0x000fffffffffffffull
#define XSCOM_ADDR_FORM1_LOW 0x000ffffffffull
#define XSCOM_ADDR_FORM1_HI 0xfff00000000ull
#define XSCOM_ADDR_FORM1_HI_SHIFT 20
/* Retries */
#define SCOM_MAX_RETRIES 100 /* Retries on busy */
#define SCOM_MAX_IND_RETRIES 10 /* Retries indirect not ready */
struct scom_device {
struct list_head link;
@ -56,7 +80,7 @@ struct scom_device {
struct miscdevice mdev;
struct mutex lock;
char name[32];
int idx;
int idx;
};
#define to_scom_dev(x) container_of((x), struct scom_device, mdev)
@ -65,80 +89,304 @@ static struct list_head scom_devices;
static DEFINE_IDA(scom_ida);
static int put_scom(struct scom_device *scom_dev, uint64_t value,
uint32_t addr)
static int __put_scom(struct scom_device *scom_dev, uint64_t value,
uint32_t addr, uint32_t *status)
{
__be32 data;
__be32 data, raw_status;
int rc;
mutex_lock(&scom_dev->lock);
data = cpu_to_be32((value >> 32) & 0xffffffff);
rc = fsi_device_write(scom_dev->fsi_dev, SCOM_DATA0_REG, &data,
sizeof(uint32_t));
if (rc)
goto bail;
return rc;
data = cpu_to_be32(value & 0xffffffff);
rc = fsi_device_write(scom_dev->fsi_dev, SCOM_DATA1_REG, &data,
sizeof(uint32_t));
if (rc)
goto bail;
return rc;
data = cpu_to_be32(SCOM_WRITE_CMD | addr);
rc = fsi_device_write(scom_dev->fsi_dev, SCOM_CMD_REG, &data,
sizeof(uint32_t));
bail:
mutex_unlock(&scom_dev->lock);
return rc;
if (rc)
return rc;
rc = fsi_device_read(scom_dev->fsi_dev, SCOM_STATUS_REG, &raw_status,
sizeof(uint32_t));
if (rc)
return rc;
*status = be32_to_cpu(raw_status);
return 0;
}
static int get_scom(struct scom_device *scom_dev, uint64_t *value,
uint32_t addr)
static int __get_scom(struct scom_device *scom_dev, uint64_t *value,
uint32_t addr, uint32_t *status)
{
__be32 result, data;
__be32 data, raw_status;
int rc;
mutex_lock(&scom_dev->lock);
*value = 0ULL;
data = cpu_to_be32(SCOM_READ_CMD | addr);
rc = fsi_device_write(scom_dev->fsi_dev, SCOM_CMD_REG, &data,
sizeof(uint32_t));
if (rc)
goto bail;
return rc;
rc = fsi_device_read(scom_dev->fsi_dev, SCOM_STATUS_REG, &raw_status,
sizeof(uint32_t));
if (rc)
return rc;
rc = fsi_device_read(scom_dev->fsi_dev, SCOM_DATA0_REG, &result,
/*
* Read the data registers even on error, so we don't have
* to interpret the status register here.
*/
rc = fsi_device_read(scom_dev->fsi_dev, SCOM_DATA0_REG, &data,
sizeof(uint32_t));
if (rc)
goto bail;
*value |= (uint64_t)be32_to_cpu(result) << 32;
rc = fsi_device_read(scom_dev->fsi_dev, SCOM_DATA1_REG, &result,
return rc;
*value |= (uint64_t)be32_to_cpu(data) << 32;
rc = fsi_device_read(scom_dev->fsi_dev, SCOM_DATA1_REG, &data,
sizeof(uint32_t));
if (rc)
goto bail;
return rc;
*value |= be32_to_cpu(data);
*status = be32_to_cpu(raw_status);
*value |= be32_to_cpu(result);
bail:
mutex_unlock(&scom_dev->lock);
return rc;
}
static int put_indirect_scom_form0(struct scom_device *scom, uint64_t value,
uint64_t addr, uint32_t *status)
{
uint64_t ind_data, ind_addr;
int rc, retries, err = 0;
if (value & ~XSCOM_DATA_IND_DATA)
return -EINVAL;
ind_addr = addr & XSCOM_ADDR_DIRECT_PART;
ind_data = (addr & XSCOM_ADDR_INDIRECT_PART) | value;
rc = __put_scom(scom, ind_data, ind_addr, status);
if (rc || (*status & SCOM_STATUS_ANY_ERR))
return rc;
for (retries = 0; retries < SCOM_MAX_IND_RETRIES; retries++) {
rc = __get_scom(scom, &ind_data, addr, status);
if (rc || (*status & SCOM_STATUS_ANY_ERR))
return rc;
err = (ind_data & XSCOM_DATA_IND_ERR_MASK) >> XSCOM_DATA_IND_ERR_SHIFT;
*status = err << SCOM_STATUS_PIB_RESP_SHIFT;
if ((ind_data & XSCOM_DATA_IND_COMPLETE) || (err != SCOM_PIB_BLOCKED))
return 0;
msleep(1);
}
return rc;
}
static int put_indirect_scom_form1(struct scom_device *scom, uint64_t value,
uint64_t addr, uint32_t *status)
{
uint64_t ind_data, ind_addr;
if (value & ~XSCOM_DATA_IND_FORM1_DATA)
return -EINVAL;
ind_addr = addr & XSCOM_ADDR_FORM1_LOW;
ind_data = value | (addr & XSCOM_ADDR_FORM1_HI) << XSCOM_ADDR_FORM1_HI_SHIFT;
return __put_scom(scom, ind_data, ind_addr, status);
}
static int get_indirect_scom_form0(struct scom_device *scom, uint64_t *value,
uint64_t addr, uint32_t *status)
{
uint64_t ind_data, ind_addr;
int rc, retries, err = 0;
ind_addr = addr & XSCOM_ADDR_DIRECT_PART;
ind_data = (addr & XSCOM_ADDR_INDIRECT_PART) | XSCOM_DATA_IND_READ;
rc = __put_scom(scom, ind_data, ind_addr, status);
if (rc || (*status & SCOM_STATUS_ANY_ERR))
return rc;
for (retries = 0; retries < SCOM_MAX_IND_RETRIES; retries++) {
rc = __get_scom(scom, &ind_data, addr, status);
if (rc || (*status & SCOM_STATUS_ANY_ERR))
return rc;
err = (ind_data & XSCOM_DATA_IND_ERR_MASK) >> XSCOM_DATA_IND_ERR_SHIFT;
*status = err << SCOM_STATUS_PIB_RESP_SHIFT;
*value = ind_data & XSCOM_DATA_IND_DATA;
if ((ind_data & XSCOM_DATA_IND_COMPLETE) || (err != SCOM_PIB_BLOCKED))
return 0;
msleep(1);
}
return rc;
}
static int raw_put_scom(struct scom_device *scom, uint64_t value,
uint64_t addr, uint32_t *status)
{
if (addr & XSCOM_ADDR_IND_FLAG) {
if (addr & XSCOM_ADDR_INF_FORM1)
return put_indirect_scom_form1(scom, value, addr, status);
else
return put_indirect_scom_form0(scom, value, addr, status);
} else
return __put_scom(scom, value, addr, status);
}
static int raw_get_scom(struct scom_device *scom, uint64_t *value,
uint64_t addr, uint32_t *status)
{
if (addr & XSCOM_ADDR_IND_FLAG) {
if (addr & XSCOM_ADDR_INF_FORM1)
return -ENXIO;
return get_indirect_scom_form0(scom, value, addr, status);
} else
return __get_scom(scom, value, addr, status);
}
static int handle_fsi2pib_status(struct scom_device *scom, uint32_t status)
{
uint32_t dummy = -1;
if (status & SCOM_STATUS_PROTECTION)
return -EPERM;
if (status & SCOM_STATUS_PARITY) {
fsi_device_write(scom->fsi_dev, SCOM_FSI2PIB_RESET_REG, &dummy,
sizeof(uint32_t));
return -EIO;
}
/* Return -EBUSY on PIB abort to force a retry */
if (status & SCOM_STATUS_PIB_ABORT)
return -EBUSY;
if (status & SCOM_STATUS_ERR_SUMMARY) {
fsi_device_write(scom->fsi_dev, SCOM_FSI2PIB_RESET_REG, &dummy,
sizeof(uint32_t));
return -EIO;
}
return 0;
}
static int handle_pib_status(struct scom_device *scom, uint8_t status)
{
uint32_t dummy = -1;
if (status == SCOM_PIB_SUCCESS)
return 0;
if (status == SCOM_PIB_BLOCKED)
return -EBUSY;
/* Reset the bridge */
fsi_device_write(scom->fsi_dev, SCOM_FSI2PIB_RESET_REG, &dummy,
sizeof(uint32_t));
switch(status) {
case SCOM_PIB_OFFLINE:
return -ENODEV;
case SCOM_PIB_BAD_ADDR:
return -ENXIO;
case SCOM_PIB_TIMEOUT:
return -ETIMEDOUT;
case SCOM_PIB_PARTIAL:
case SCOM_PIB_CLK_ERR:
case SCOM_PIB_PARITY_ERR:
default:
return -EIO;
}
}
static int put_scom(struct scom_device *scom, uint64_t value,
uint64_t addr)
{
uint32_t status, dummy = -1;
int rc, retries;
for (retries = 0; retries < SCOM_MAX_RETRIES; retries++) {
rc = raw_put_scom(scom, value, addr, &status);
if (rc) {
/* Try resetting the bridge if FSI fails */
if (rc != -ENODEV && retries == 0) {
fsi_device_write(scom->fsi_dev, SCOM_FSI2PIB_RESET_REG,
&dummy, sizeof(uint32_t));
rc = -EBUSY;
} else
return rc;
} else
rc = handle_fsi2pib_status(scom, status);
if (rc && rc != -EBUSY)
break;
if (rc == 0) {
rc = handle_pib_status(scom,
(status & SCOM_STATUS_PIB_RESP_MASK)
>> SCOM_STATUS_PIB_RESP_SHIFT);
if (rc && rc != -EBUSY)
break;
}
if (rc == 0)
break;
msleep(1);
}
return rc;
}
static int get_scom(struct scom_device *scom, uint64_t *value,
uint64_t addr)
{
uint32_t status, dummy = -1;
int rc, retries;
for (retries = 0; retries < SCOM_MAX_RETRIES; retries++) {
rc = raw_get_scom(scom, value, addr, &status);
if (rc) {
/* Try resetting the bridge if FSI fails */
if (rc != -ENODEV && retries == 0) {
fsi_device_write(scom->fsi_dev, SCOM_FSI2PIB_RESET_REG,
&dummy, sizeof(uint32_t));
rc = -EBUSY;
} else
return rc;
} else
rc = handle_fsi2pib_status(scom, status);
if (rc && rc != -EBUSY)
break;
if (rc == 0) {
rc = handle_pib_status(scom,
(status & SCOM_STATUS_PIB_RESP_MASK)
>> SCOM_STATUS_PIB_RESP_SHIFT);
if (rc && rc != -EBUSY)
break;
}
if (rc == 0)
break;
msleep(1);
}
return rc;
}
static ssize_t scom_read(struct file *filep, char __user *buf, size_t len,
loff_t *offset)
{
int rc;
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;
int rc;
if (len != sizeof(uint64_t))
return -EINVAL;
mutex_lock(&scom->lock);
rc = get_scom(scom, &val, *offset);
mutex_unlock(&scom->lock);
if (rc) {
dev_dbg(dev, "get_scom fail:%d\n", rc);
return rc;
@ -169,7 +417,9 @@ static ssize_t scom_write(struct file *filep, const char __user *buf,
return -EINVAL;
}
mutex_lock(&scom->lock);
rc = put_scom(scom, val, *offset);
mutex_unlock(&scom->lock);
if (rc) {
dev_dbg(dev, "put_scom failed with:%d\n", rc);
return rc;
@ -193,11 +443,125 @@ static loff_t scom_llseek(struct file *file, loff_t offset, int whence)
return offset;
}
static void raw_convert_status(struct scom_access *acc, uint32_t status)
{
acc->pib_status = (status & SCOM_STATUS_PIB_RESP_MASK) >>
SCOM_STATUS_PIB_RESP_SHIFT;
acc->intf_errors = 0;
if (status & SCOM_STATUS_PROTECTION)
acc->intf_errors |= SCOM_INTF_ERR_PROTECTION;
else if (status & SCOM_STATUS_PARITY)
acc->intf_errors |= SCOM_INTF_ERR_PARITY;
else if (status & SCOM_STATUS_PIB_ABORT)
acc->intf_errors |= SCOM_INTF_ERR_ABORT;
else if (status & SCOM_STATUS_ERR_SUMMARY)
acc->intf_errors |= SCOM_INTF_ERR_UNKNOWN;
}
static int scom_raw_read(struct scom_device *scom, void __user *argp)
{
struct scom_access acc;
uint32_t status;
int rc;
if (copy_from_user(&acc, argp, sizeof(struct scom_access)))
return -EFAULT;
rc = raw_get_scom(scom, &acc.data, acc.addr, &status);
if (rc)
return rc;
raw_convert_status(&acc, status);
if (copy_to_user(argp, &acc, sizeof(struct scom_access)))
return -EFAULT;
return 0;
}
static int scom_raw_write(struct scom_device *scom, void __user *argp)
{
u64 prev_data, mask, data;
struct scom_access acc;
uint32_t status;
int rc;
if (copy_from_user(&acc, argp, sizeof(struct scom_access)))
return -EFAULT;
if (acc.mask) {
rc = raw_get_scom(scom, &prev_data, acc.addr, &status);
if (rc)
return rc;
if (status & SCOM_STATUS_ANY_ERR)
goto fail;
mask = acc.mask;
} else {
prev_data = mask = -1ull;
}
data = (prev_data & ~mask) | (acc.data & mask);
rc = raw_put_scom(scom, data, acc.addr, &status);
if (rc)
return rc;
fail:
raw_convert_status(&acc, status);
if (copy_to_user(argp, &acc, sizeof(struct scom_access)))
return -EFAULT;
return 0;
}
static int scom_reset(struct scom_device *scom, void __user *argp)
{
uint32_t flags, dummy = -1;
int rc = 0;
if (get_user(flags, (__u32 __user *)argp))
return -EFAULT;
if (flags & SCOM_RESET_PIB)
rc = fsi_device_write(scom->fsi_dev, SCOM_PIB_RESET_REG, &dummy,
sizeof(uint32_t));
if (!rc && (flags & (SCOM_RESET_PIB | SCOM_RESET_INTF)))
rc = fsi_device_write(scom->fsi_dev, SCOM_FSI2PIB_RESET_REG, &dummy,
sizeof(uint32_t));
return rc;
}
static int scom_check(struct scom_device *scom, void __user *argp)
{
/* Still need to find out how to get "protected" */
return put_user(SCOM_CHECK_SUPPORTED, (__u32 __user *)argp);
}
static long scom_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct miscdevice *mdev = file->private_data;
struct scom_device *scom = to_scom_dev(mdev);
void __user *argp = (void __user *)arg;
int rc = -ENOTTY;
mutex_lock(&scom->lock);
switch(cmd) {
case FSI_SCOM_CHECK:
rc = scom_check(scom, argp);
break;
case FSI_SCOM_READ:
rc = scom_raw_read(scom, argp);
break;
case FSI_SCOM_WRITE:
rc = scom_raw_write(scom, argp);
break;
case FSI_SCOM_RESET:
rc = scom_reset(scom, argp);
break;
}
mutex_unlock(&scom->lock);
return rc;
}
static const struct file_operations scom_fops = {
.owner = THIS_MODULE,
.llseek = scom_llseek,
.read = scom_read,
.write = scom_write,
.owner = THIS_MODULE,
.llseek = scom_llseek,
.read = scom_read,
.write = scom_write,
.unlocked_ioctl = scom_ioctl,
};
static int scom_probe(struct device *dev)

58
include/uapi/linux/fsi.h Normal file
View File

@ -0,0 +1,58 @@
/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
#ifndef _UAPI_LINUX_FSI_H
#define _UAPI_LINUX_FSI_H
#include <linux/types.h>
#include <linux/ioctl.h>
/*
* /dev/scom "raw" ioctl interface
*
* The driver supports a high level "read/write" interface which
* handles retries and converts the status to Linux error codes,
* however low level tools an debugger need to access the "raw"
* HW status information and interpret it themselves, so this
* ioctl interface is also provided for their use case.
*/
/* Structure for SCOM read/write */
struct scom_access {
__u64 addr; /* SCOM address, supports indirect */
__u64 data; /* SCOM data (in for write, out for read) */
__u64 mask; /* Data mask for writes */
__u32 intf_errors; /* Interface error flags */
#define SCOM_INTF_ERR_PARITY 0x00000001 /* Parity error */
#define SCOM_INTF_ERR_PROTECTION 0x00000002 /* Blocked by secure boot */
#define SCOM_INTF_ERR_ABORT 0x00000004 /* PIB reset during access */
#define SCOM_INTF_ERR_UNKNOWN 0x80000000 /* Unknown error */
/*
* Note: Any other bit set in intf_errors need to be considered as an
* error. Future implementations may define new error conditions. The
* pib_status below is only valid if intf_errors is 0.
*/
__u8 pib_status; /* 3-bit PIB status */
#define SCOM_PIB_SUCCESS 0 /* Access successful */
#define SCOM_PIB_BLOCKED 1 /* PIB blocked, pls retry */
#define SCOM_PIB_OFFLINE 2 /* Chiplet offline */
#define SCOM_PIB_PARTIAL 3 /* Partial good */
#define SCOM_PIB_BAD_ADDR 4 /* Invalid address */
#define SCOM_PIB_CLK_ERR 5 /* Clock error */
#define SCOM_PIB_PARITY_ERR 6 /* Parity error on the PIB bus */
#define SCOM_PIB_TIMEOUT 7 /* Bus timeout */
__u8 pad;
};
/* Flags for SCOM check */
#define SCOM_CHECK_SUPPORTED 0x00000001 /* Interface supported */
#define SCOM_CHECK_PROTECTED 0x00000002 /* Interface blocked by secure boot */
/* Flags for SCOM reset */
#define SCOM_RESET_INTF 0x00000001 /* Reset interface */
#define SCOM_RESET_PIB 0x00000002 /* Reset PIB */
#define FSI_SCOM_CHECK _IOR('s', 0x00, __u32)
#define FSI_SCOM_READ _IOWR('s', 0x01, struct scom_access)
#define FSI_SCOM_WRITE _IOWR('s', 0x02, struct scom_access)
#define FSI_SCOM_RESET _IOW('s', 0x03, __u32)
#endif /* _UAPI_LINUX_FSI_H */