sfc: Allocate and link PIO buffers; map them with write-combining

Try to allocate a segment of PIO buffer to each TX channel.  If
allocation fails, log an error but continue.

PIO buffers must be mapped separately from the NIC registers, with
write-combining enabled.  Where the host page size is 4K, we could
potentially map each VI's registers and PIO buffer separately.
However, this would add significant complexity, and we also need to
support architectures such as POWER which have a greater page size.
So make a single contiguous write-combining mapping after the
uncacheable mapping, aligned to the host page size, and link PIO
buffers there.  Where necessary, allocate additional VIs within
the write-combining mapping purely for access to PIO buffers.

Link all TX buffers to TX queues and the additional VIs in
efx_ef10_dimension_resources() and in efx_ef10_init_nic() after
an MC reboot.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/drivers/net/ethernet/sfc/nic.h b/drivers/net/ethernet/sfc/nic.h
index fda29d39032f..db70005999c3 100644
--- a/drivers/net/ethernet/sfc/nic.h
+++ b/drivers/net/ethernet/sfc/nic.h
@@ -389,6 +389,12 @@ enum {
 	EF10_STAT_COUNT
 };
 
+/* Maximum number of TX PIO buffers we may allocate to a function.
+ * This matches the total number of buffers on each SFC9100-family
+ * controller.
+ */
+#define EF10_TX_PIOBUF_COUNT 16
+
 /**
  * struct efx_ef10_nic_data - EF10 architecture NIC state
  * @mcdi_buf: DMA buffer for MCDI
@@ -397,6 +403,13 @@ enum {
  * @n_allocated_vis: Number of VIs allocated to this function
  * @must_realloc_vis: Flag: VIs have yet to be reallocated after MC reboot
  * @must_restore_filters: Flag: filters have yet to be restored after MC reboot
+ * @n_piobufs: Number of PIO buffers allocated to this function
+ * @wc_membase: Base address of write-combining mapping of the memory BAR
+ * @pio_write_base: Base address for writing PIO buffers
+ * @pio_write_vi_base: Relative VI number for @pio_write_base
+ * @piobuf_handle: Handle of each PIO buffer allocated
+ * @must_restore_piobufs: Flag: PIO buffers have yet to be restored after MC
+ *	reboot
  * @rx_rss_context: Firmware handle for our RSS context
  * @stats: Hardware statistics
  * @workaround_35388: Flag: firmware supports workaround for bug 35388
@@ -412,6 +425,11 @@ struct efx_ef10_nic_data {
 	unsigned int n_allocated_vis;
 	bool must_realloc_vis;
 	bool must_restore_filters;
+	unsigned int n_piobufs;
+	void __iomem *wc_membase, *pio_write_base;
+	unsigned int pio_write_vi_base;
+	unsigned int piobuf_handle[EF10_TX_PIOBUF_COUNT];
+	bool must_restore_piobufs;
 	u32 rx_rss_context;
 	u64 stats[EF10_STAT_COUNT];
 	bool workaround_35388;