[PATCH v9 7/7] cdx: add device attributes

Nipun Gupta
2023-03-07T13:22:29Z

Create sysfs entry for CDX devices.

Sysfs entries provided in each of the CDX device detected by
the CDX controller
- vendor id
- device id
- remove
- reset of the device.
- driver override

Signed-off-by: Puneet Gupta <puneet.gupta@amd.com>
Signed-off-by: Nipun Gupta <nipun.gupta@amd.com>
Signed-off-by: Tarak Reddy <tarak.reddy@amd.com>
Reviewed-by: Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@amd.com>
Tested-by: Nikhil Agarwal <nikhil.agarwal@amd.com>
---
Documentation/ABI/testing/sysfs-bus-cdx | 44 +++++++
drivers/cdx/cdx.c | 145 ++++++++++++++++++++++++
drivers/cdx/controller/cdx_controller.c | 19 ++++
drivers/cdx/controller/mcdi_functions.c | 14 +++
drivers/cdx/controller/mcdi_functions.h | 11 ++
include/linux/cdx/cdx_bus.h | 27 +++++
6 files changed, 260 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-cdx b/Documentation/ABI/testing/sysfs-bus-cdx
index 063d1a0dd866..c553ce3a449a 100644
--- a/Documentation/ABI/testing/sysfs-bus-cdx
+++ b/Documentation/ABI/testing/sysfs-bus-cdx
@@ -10,3 +10,47 @@ Description:
For example::

# echo 1 > /sys/bus/cdx/rescan
+
+What: /sys/bus/cdx/devices/.../vendor
+Date: March 2023
+Contact: nipun.gupta@amd.com
+Description:
+ Vendor ID for this CDX device. Vendor ID is 16 bit
+ identifier which is specific to the device manufacturer.
+ Combination of Vendor ID and Device ID identifies a device.
+
+What: /sys/bus/cdx/devices/.../device
+Date: March 2023
+Contact: nipun.gupta@amd.com
+Description:
+ Device ID for this CDX device. Device ID is a 16 bit
+ identifier to identify a device type within the range
+ of a device manufacturer.
+ Combination of Vendor ID and Device ID identifies a device.
+
+What: /sys/bus/cdx/devices/.../reset
+Date: March 2023
+Contact: nipun.gupta@amd.com
+Description:
+ Writing a non-zero value to this file resets the CDX device.
+ On resetting the device, the corresponding driver is notified
+ twice, once before the device is being reset, and again after
+ the reset has been complete.
+
+ For example::
+
+ # echo 1 > /sys/bus/cdx/.../reset
+
+What: /sys/bus/cdx/devices/.../remove
+Date: March 2023
+Contact: tarak.reddy@amd.com
+Description:
+ Writing a non-zero value to this file removes the corresponding
+ device from the CDX bus. If the device is to be reconfigured
+ reconfigured in the Hardware, the device can be removed, so
+ that the device driver does not access the device while it is
+ being reconfigured.
+
+ For example::
+
+ # echo 1 > /sys/bus/cdx/devices/.../remove
diff --git a/drivers/cdx/cdx.c b/drivers/cdx/cdx.c
index c981232486dd..0c4f300373e5 100644
--- a/drivers/cdx/cdx.c
+++ b/drivers/cdx/cdx.c
@@ -71,6 +71,39 @@
/* CDX controllers registered with the CDX bus */
static DEFINE_XARRAY_ALLOC(cdx_controllers);

+/**
+ * cdx_dev_reset - Reset a CDX device
+ * @dev: CDX device
+ *
+ * Return: -errno on failure, 0 on success.
+ */
+int cdx_dev_reset(struct device *dev)
+{
+ struct cdx_device *cdx_dev = to_cdx_device(dev);
+ struct cdx_controller *cdx = cdx_dev->cdx;
+ struct cdx_device_config dev_config;
+ struct cdx_driver *cdx_drv;
+ int ret;
+
+ cdx_drv = to_cdx_driver(dev->driver);
+ /* Notify driver that device is being reset */
+ if (cdx_drv && cdx_drv->reset_prepare)
+ cdx_drv->reset_prepare(cdx_dev);
+
+ dev_config.type = CDX_DEV_RESET_CONF;
+ ret = cdx->ops->dev_configure(cdx, cdx_dev->bus_num,
+ cdx_dev->dev_num, &dev_config);
+ if (ret)
+ dev_err(dev, "cdx device reset failed\n");
+
+ /* Notify driver that device reset is complete */
+ if (cdx_drv && cdx_drv->reset_done)
+ cdx_drv->reset_done(cdx_dev);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(cdx_dev_reset);
+
/**
* cdx_unregister_device - Unregister a CDX device
* @dev: CDX device
@@ -237,6 +270,117 @@ static int cdx_dma_configure(struct device *dev)
return 0;
}

+/* show configuration fields */
+#define cdx_config_attr(field, format_string) \
+static ssize_t \
+field##_show(struct device *dev, struct device_attribute *attr, char *buf) \
+{ \
+ struct cdx_device *cdx_dev = to_cdx_device(dev); \
+ return sysfs_emit(buf, format_string, cdx_dev->field); \
+} \
+static DEVICE_ATTR_RO(field)
+
+cdx_config_attr(vendor, "0x%04x\n");
+cdx_config_attr(device, "0x%04x\n");
+
+static ssize_t remove_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ unsigned long val = 0;
+
+ if (kstrtoul(buf, 0, &val) < 0)
+ return -EINVAL;
+
+ if (!val)
+ return -EINVAL;
+
+ if (device_remove_file_self(dev, attr)) {
+ int ret;
+
+ ret = cdx_unregister_device(dev, NULL);
+ if (ret)
+ return ret;
+ }
+
+ return count;
+}
+static DEVICE_ATTR_WO(remove);
+
+static ssize_t reset_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ unsigned long val = 0;
+ int ret = 0;
+
+ if (kstrtoul(buf, 0, &val) < 0)
+ return -EINVAL;
+
+ if (!val)
+ return -EINVAL;
+
+ ret = cdx_dev_reset(dev);
+ if (ret)
+ return ret;
+
+ return count;
+}
+static DEVICE_ATTR_WO(reset);
+
+static ssize_t driver_override_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct cdx_device *cdx_dev = to_cdx_device(dev);
+ const char *old = cdx_dev->driver_override;
+ char *driver_override;
+ char *cp;
+
+ if (WARN_ON(dev->bus != &cdx_bus_type))
+ return -EINVAL;
+
+ if (count >= (PAGE_SIZE - 1))
+ return -EINVAL;
+
+ driver_override = kstrndup(buf, count, GFP_KERNEL);
+ if (!driver_override)
+ return -ENOMEM;
+
+ cp = strchr(driver_override, '\n');
+ if (cp)
+ *cp = '\0';
+
+ if (strlen(driver_override)) {
+ cdx_dev->driver_override = driver_override;
+ } else {
+ kfree(driver_override);
+ cdx_dev->driver_override = NULL;
+ }
+
+ kfree(old);
+
+ return count;
+}
+
+static ssize_t driver_override_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct cdx_device *cdx_dev = to_cdx_device(dev);
+
+ return sysfs_emit(buf, "%s\n", cdx_dev->driver_override);
+}
+static DEVICE_ATTR_RW(driver_override);
+
+static struct attribute *cdx_dev_attrs[] = {
+ &dev_attr_remove.attr,
+ &dev_attr_reset.attr,
+ &dev_attr_vendor.attr,
+ &dev_attr_device.attr,
+ &dev_attr_driver_override.attr,
+ NULL,
+};
+ATTRIBUTE_GROUPS(cdx_dev);
+
static ssize_t rescan_store(struct bus_type *bus,
const char *buf, size_t count)
{
@@ -279,6 +423,7 @@ struct bus_type cdx_bus_type = {
.shutdown = cdx_shutdown,
.dma_configure = cdx_dma_configure,
.bus_groups = cdx_bus_groups,
+ .dev_groups = cdx_dev_groups,
};
EXPORT_SYMBOL_GPL(cdx_bus_type);

diff --git a/drivers/cdx/controller/cdx_controller.c b/drivers/cdx/controller/cdx_controller.c
index 0d1826980935..b1c2e96589d1 100644
--- a/drivers/cdx/controller/cdx_controller.c
+++ b/drivers/cdx/controller/cdx_controller.c
@@ -45,6 +45,24 @@ void cdx_rpmsg_pre_remove(struct cdx_controller *cdx)
cdx_mcdi_wait_for_quiescence(cdx->priv, MCDI_RPC_TIMEOUT);
}

+static int cdx_configure_device(struct cdx_controller *cdx,
+ u8 bus_num, u8 dev_num,
+ struct cdx_device_config *dev_config)
+{
+ int ret = 0;
+
+ switch (dev_config->type) {
+ case CDX_DEV_RESET_CONF:
+ ret = cdx_mcdi_reset_device(cdx->priv, bus_num, dev_num);
+ break;
+ default:
+ dev_err(cdx->dev, "Invalid device configuration flag\n");
+ ret = -EINVAL;
+ }
+
+ return ret;
+}
+
static int cdx_scan_devices(struct cdx_controller *cdx)
{
struct cdx_mcdi *cdx_mcdi = cdx->priv;
@@ -104,6 +122,7 @@ static int cdx_scan_devices(struct cdx_controller *cdx)

static struct cdx_ops cdx_ops = {
.scan = cdx_scan_devices,
+ .dev_configure = cdx_configure_device,
};

static int xlnx_cdx_probe(struct platform_device *pdev)
diff --git a/drivers/cdx/controller/mcdi_functions.c b/drivers/cdx/controller/mcdi_functions.c
index 012b52881dd5..0158f26533dd 100644
--- a/drivers/cdx/controller/mcdi_functions.c
+++ b/drivers/cdx/controller/mcdi_functions.c
@@ -123,3 +123,17 @@ int cdx_mcdi_get_dev_config(struct cdx_mcdi *cdx,

return 0;
}
+
+int cdx_mcdi_reset_device(struct cdx_mcdi *cdx, u8 bus_num, u8 dev_num)
+{
+ MCDI_DECLARE_BUF(inbuf, MC_CMD_CDX_DEVICE_RESET_IN_LEN);
+ int ret;
+
+ MCDI_SET_DWORD(inbuf, CDX_DEVICE_RESET_IN_BUS, bus_num);
+ MCDI_SET_DWORD(inbuf, CDX_DEVICE_RESET_IN_DEVICE, dev_num);
+
+ ret = cdx_mcdi_rpc(cdx, MC_CMD_CDX_DEVICE_RESET, inbuf, sizeof(inbuf),
+ NULL, 0, NULL);
+
+ return ret;
+}
diff --git a/drivers/cdx/controller/mcdi_functions.h b/drivers/cdx/controller/mcdi_functions.h
index 6bf5a4a0778f..7440ace5539a 100644
--- a/drivers/cdx/controller/mcdi_functions.h
+++ b/drivers/cdx/controller/mcdi_functions.h
@@ -47,4 +47,15 @@ int cdx_mcdi_get_dev_config(struct cdx_mcdi *cdx,
u8 bus_num, u8 dev_num,
struct cdx_dev_params *dev_params);

+/**
+ * cdx_mcdi_reset_device - Reset cdx device represented by bus_num:dev_num
+ * @cdx: pointer to MCDI interface.
+ * @bus_num: Bus number.
+ * @dev_num: Device number.
+ *
+ * Return: 0 on success, <0 on failure
+ */
+int cdx_mcdi_reset_device(struct cdx_mcdi *cdx,
+ u8 bus_num, u8 dev_num);
+
#endif /* CDX_MCDI_FUNCTIONS_H */
diff --git a/include/linux/cdx/cdx_bus.h b/include/linux/cdx/cdx_bus.h
index d134e0104724..35ef41d8a61a 100644
--- a/include/linux/cdx/cdx_bus.h
+++ b/include/linux/cdx/cdx_bus.h
@@ -21,8 +21,20 @@
/* Forward declaration for CDX controller */
struct cdx_controller;

+enum {
+ CDX_DEV_RESET_CONF,
+};
+
+struct cdx_device_config {
+ u8 type;
+};
+
typedef int (*cdx_scan_cb)(struct cdx_controller *cdx);

+typedef int (*cdx_dev_configure_cb)(struct cdx_controller *cdx,
+ u8 bus_num, u8 dev_num,
+ struct cdx_device_config *dev_config);
+
/**
* CDX_DEVICE_DRIVER_OVERRIDE - macro used to describe a CDX device with
* override_only flags.
@@ -39,9 +51,12 @@ typedef int (*cdx_scan_cb)(struct cdx_controller *cdx);
/**
* struct cdx_ops - Callbacks supported by CDX controller.
* @scan: scan the devices on the controller
+ * @dev_configure: configuration like reset, master_enable,
+ * msi_config etc for a CDX device
*/
struct cdx_ops {
cdx_scan_cb scan;
+ cdx_dev_configure_cb dev_configure;
};

/**
@@ -101,6 +116,8 @@ struct cdx_device {
* @probe: Function called when a device is added
* @remove: Function called when a device is removed
* @shutdown: Function called at shutdown time to quiesce the device
+ * @reset_prepare: Function called before is reset to notify driver
+ * @reset_done: Function called after reset is complete to notify driver
* @driver_managed_dma: Device driver doesn't use kernel DMA API for DMA.
* For most device drivers, no need to care about this flag
* as long as all DMAs are handled through the kernel DMA API.
@@ -115,6 +132,8 @@ struct cdx_driver {
int (*probe)(struct cdx_device *dev);
int (*remove)(struct cdx_device *dev);
void (*shutdown)(struct cdx_device *dev);
+ void (*reset_prepare)(struct cdx_device *dev);
+ void (*reset_done)(struct cdx_device *dev);
bool driver_managed_dma;
};

@@ -144,4 +163,12 @@ void cdx_driver_unregister(struct cdx_driver *cdx_driver);

extern struct bus_type cdx_bus_type;

+/**
+ * cdx_dev_reset - Reset CDX device
+ * @dev: device pointer
+ *
+ * Return: 0 for success, -errno on failure
+ */
+int cdx_dev_reset(struct device *dev);
+
#endif /* _CDX_BUS_H_ */
--
2.17.1