[PATCH net-next 0/2] sfc: Add EF100 BAR config support

[PATCH net-next 0/2] sfc: Add EF100 BAR config support

[Martin Habets]

The EF100 NICs allow for different register layouts of a PCI memory BAR.
This series provides the framework to switch this layout at runtime.

Subsequent patch series will use this to add support for vDPA.
---

Martin Habets (2):
      sfc: Add EF100 BAR config support
      sfc: Implement change of BAR configuration


 drivers/net/ethernet/sfc/ef100_nic.c |   80 ++++++++++++++++++++++++++++++++++
 drivers/net/ethernet/sfc/ef100_nic.h |    6 +++
 2 files changed, 86 insertions(+)

--
Martin Habets <habetsm.xilinx@gmail.com>

[PATCH net-next 1/2] sfc: Add EF100 BAR config support

[Martin Habets]

Provide a "bar_config" file in the sysfs directory of the PCI device.
This can be used to switch the PCI BAR layout to/from vDPA mode.

Signed-off-by: Martin Habets <habetsm.xilinx@gmail.com>
---
 drivers/net/ethernet/sfc/ef100_nic.c |   45 ++++++++++++++++++++++++++++++++++
 drivers/net/ethernet/sfc/ef100_nic.h |    6 +++++
 2 files changed, 51 insertions(+)

diff --git a/drivers/net/ethernet/sfc/ef100_nic.c b/drivers/net/ethernet/sfc/ef100_nic.c
index f89e695cf8ac..218db3cb31eb 100644
--- a/drivers/net/ethernet/sfc/ef100_nic.c
+++ b/drivers/net/ethernet/sfc/ef100_nic.c
@@ -704,6 +704,49 @@ static unsigned int efx_ef100_recycle_ring_size(const struct efx_nic *efx)
 	return 10 * EFX_RECYCLE_RING_SIZE_10G;
 }
 
+/* BAR configuration */
+static ssize_t bar_config_show(struct device *dev,
+			       struct device_attribute *attr, char *buf_out)
+{
+	struct efx_nic *efx = pci_get_drvdata(to_pci_dev(dev));
+	struct ef100_nic_data *nic_data = efx->nic_data;
+
+	switch (nic_data->bar_config) {
+	case EF100_BAR_CONFIG_EF100:
+		sprintf(buf_out, "EF100\n");
+		break;
+	case EF100_BAR_CONFIG_VDPA:
+		sprintf(buf_out, "vDPA\n");
+		break;
+	default: /* this should not happen */
+		WARN_ON_ONCE(1);
+		return 0;
+	}
+
+	return strlen(buf_out);
+}
+
+static ssize_t bar_config_store(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf, size_t count)
+{
+	struct efx_nic *efx = pci_get_drvdata(to_pci_dev(dev));
+	struct ef100_nic_data *nic_data = efx->nic_data;
+	enum ef100_bar_config new_config;
+
+	if (!strncasecmp(buf, "ef100", min_t(size_t, count, 5)))
+		new_config = EF100_BAR_CONFIG_EF100;
+	else if (!strncasecmp(buf, "vdpa", min_t(size_t, count, 4)))
+		new_config = EF100_BAR_CONFIG_VDPA;
+	else
+		return -EIO;
+
+	nic_data->bar_config = new_config;
+	return count;
+}
+
+static DEVICE_ATTR_RW(bar_config);
+
 static int compare_versions(const char *a, const char *b)
 {
 	int a_major, a_minor, a_point, a_patch;
@@ -1039,6 +1082,7 @@ static int ef100_probe_main(struct efx_nic *efx)
 		goto fail;
 	}
 
+	device_create_file(&efx->pci_dev->dev, &dev_attr_bar_config);
 	return 0;
 fail:
 	return rc;
@@ -1072,6 +1116,7 @@ void ef100_remove(struct efx_nic *efx)
 {
 	struct ef100_nic_data *nic_data = efx->nic_data;
 
+	device_remove_file(&efx->pci_dev->dev, &dev_attr_bar_config);
 	efx_mcdi_detach(efx);
 	efx_mcdi_fini(efx);
 	if (nic_data)
diff --git a/drivers/net/ethernet/sfc/ef100_nic.h b/drivers/net/ethernet/sfc/ef100_nic.h
index 744dbbdb4adc..64b82cae6b54 100644
--- a/drivers/net/ethernet/sfc/ef100_nic.h
+++ b/drivers/net/ethernet/sfc/ef100_nic.h
@@ -61,6 +61,11 @@ enum {
 	EF100_STAT_COUNT
 };
 
+enum ef100_bar_config {
+	EF100_BAR_CONFIG_EF100,
+	EF100_BAR_CONFIG_VDPA,
+};
+
 struct ef100_nic_data {
 	struct efx_nic *efx;
 	struct efx_buffer mcdi_buf;
@@ -70,6 +75,7 @@ struct ef100_nic_data {
 	unsigned int pf_index;
 	u16 warm_boot_count;
 	u8 port_id[ETH_ALEN];
+	enum ef100_bar_config bar_config;
 	DECLARE_BITMAP(evq_phases, EFX_MAX_CHANNELS);
 	u64 stats[EF100_STAT_COUNT];
 	u16 tso_max_hdr_len;

[PATCH net-next 2/2] sfc: Implement change of BAR configuration

[Martin Habets]

Placeholders are added for vDPA. These will be assigned with
a later patch.

Signed-off-by: Martin Habets <habetsm.xilinx@gmail.com>
---
 drivers/net/ethernet/sfc/ef100_nic.c |   39 ++++++++++++++++++++++++++++++++--
 1 file changed, 37 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/sfc/ef100_nic.c b/drivers/net/ethernet/sfc/ef100_nic.c
index 218db3cb31eb..ce4b7b4e705e 100644
--- a/drivers/net/ethernet/sfc/ef100_nic.c
+++ b/drivers/net/ethernet/sfc/ef100_nic.c
@@ -704,7 +704,25 @@ static unsigned int efx_ef100_recycle_ring_size(const struct efx_nic *efx)
 	return 10 * EFX_RECYCLE_RING_SIZE_10G;
 }
 
-/* BAR configuration */
+/* BAR configuration.
+ * To change BAR configuration we tear down the current configuration (which
+ * leaves the hardware in the PROBED state), and then initialise the new
+ * BAR state.
+ */
+static struct {
+	int (*init)(struct efx_probe_data *probe_data);
+	void (*fini)(struct efx_probe_data *probe_data);
+} bar_config_std[] = {
+	[EF100_BAR_CONFIG_EF100] = {
+		.init = ef100_probe_netdev,
+		.fini = ef100_remove_netdev
+	},
+	[EF100_BAR_CONFIG_VDPA] = {
+		.init = NULL,	/* TODO: assign these */
+		.fini = NULL
+	},
+};
+
 static ssize_t bar_config_show(struct device *dev,
 			       struct device_attribute *attr, char *buf_out)
 {
@@ -732,7 +750,9 @@ static ssize_t bar_config_store(struct device *dev,
 {
 	struct efx_nic *efx = pci_get_drvdata(to_pci_dev(dev));
 	struct ef100_nic_data *nic_data = efx->nic_data;
-	enum ef100_bar_config new_config;
+	enum ef100_bar_config new_config, old_config;
+	struct efx_probe_data *probe_data;
+	int rc;
 
 	if (!strncasecmp(buf, "ef100", min_t(size_t, count, 5)))
 		new_config = EF100_BAR_CONFIG_EF100;
@@ -741,7 +761,22 @@ static ssize_t bar_config_store(struct device *dev,
 	else
 		return -EIO;
 
+	old_config = nic_data->bar_config;
+	if (new_config == old_config)
+		return count;
+
+	probe_data = container_of(efx, struct efx_probe_data, efx);
+	if (bar_config_std[old_config].fini)
+		bar_config_std[old_config].fini(probe_data);
+
 	nic_data->bar_config = new_config;
+	if (bar_config_std[new_config].init) {
+		rc = bar_config_std[new_config].init(probe_data);
+		if (rc)
+			return rc;
+	}
+
+	pci_info(efx->pci_dev, "BAR configuration changed to %s", buf);
 	return count;
 }
 

Re: [PATCH net-next 1/2] sfc: Add EF100 BAR config support

[Andrew Lunn]

On Wed, Jul 06, 2022 at 05:21:13PM +0100, Martin Habets wrote:
> Provide a "bar_config" file in the sysfs directory of the PCI device.
> This can be used to switch the PCI BAR layout to/from vDPA mode.

You probably should also Cc: the PCI maintainers.

    Andrew

Re: [PATCH net-next 1/2] sfc: Add EF100 BAR config support

[Jakub Kicinski]

On Wed, 6 Jul 2022 19:25:01 +0200 Andrew Lunn wrote:
> On Wed, Jul 06, 2022 at 05:21:13PM +0100, Martin Habets wrote:
> > Provide a "bar_config" file in the sysfs directory of the PCI device.
> > This can be used to switch the PCI BAR layout to/from vDPA mode.  
> 
> You probably should also Cc: the PCI maintainers.

And virtio people, just in case.