[PATCH 10/19] thunderbolt: Make the ring register layout configurable

[Sven Peter]

The ring descriptor and options registers are laid out differently on
the Apple NHI. Describe their offsets and strides with a
tb_nhi_ring_layout struct that NHI drivers can override.

Signed-off-by: Sven Peter <sven at kernel.org>
---
 drivers/thunderbolt/nhi.c   | 30 ++++++++++++++++++++++++------
 drivers/thunderbolt/nhi.h   | 18 ++++++++++++++++++
 include/linux/thunderbolt.h |  3 +++
 3 files changed, 45 insertions(+), 6 deletions(-)

diff --git a/drivers/thunderbolt/nhi.c b/drivers/thunderbolt/nhi.c
index fc54ff7edfb9..3a3d334e69fd 100644
--- a/drivers/thunderbolt/nhi.c
+++ b/drivers/thunderbolt/nhi.c
@@ -176,19 +176,32 @@ void nhi_disable_interrupts(struct tb_nhi *nhi)
 
 /* ring helper methods */
 
+static const struct tb_nhi_ring_layout nhi_default_ring_layout = {
+	.tx_desc_base = REG_TX_RING_BASE,
+	.rx_desc_base = REG_RX_RING_BASE,
+	.desc_stride = 16,
+	.tx_options_base = REG_TX_OPTIONS_BASE,
+	.rx_options_base = REG_RX_OPTIONS_BASE,
+	.options_stride = 32,
+};
+
 static void __iomem *ring_desc_base(struct tb_ring *ring)
 {
+	const struct tb_nhi_ring_layout *layout = ring->nhi->ring_layout;
 	void __iomem *io = ring->nhi->iobase;
-	io += ring->is_tx ? REG_TX_RING_BASE : REG_RX_RING_BASE;
-	io += ring->hop * 16;
+
+	io += ring->is_tx ? layout->tx_desc_base : layout->rx_desc_base;
+	io += ring->hop * layout->desc_stride;
 	return io;
 }
 
 static void __iomem *ring_options_base(struct tb_ring *ring)
 {
+	const struct tb_nhi_ring_layout *layout = ring->nhi->ring_layout;
 	void __iomem *io = ring->nhi->iobase;
-	io += ring->is_tx ? REG_TX_OPTIONS_BASE : REG_RX_OPTIONS_BASE;
-	io += ring->hop * 32;
+
+	io += ring->is_tx ? layout->tx_options_base : layout->rx_options_base;
+	io += ring->hop * layout->options_stride;
 	return io;
 }
 
@@ -215,8 +228,10 @@ static void ring_iowrite32desc(struct tb_ring *ring, u32 value, u32 offset)
 
 static void ring_iowrite64desc(struct tb_ring *ring, u64 value, u32 offset)
 {
-	iowrite32(value, ring_desc_base(ring) + offset);
-	iowrite32(value >> 32, ring_desc_base(ring) + offset + 4);
+	void __iomem *base = ring_desc_base(ring);
+
+	iowrite32(value, base + offset);
+	iowrite32(value >> 32, base + offset + 4);
 }
 
 static void ring_iowrite32options(struct tb_ring *ring, u32 value, u32 offset)
@@ -1253,6 +1268,9 @@ int nhi_probe(struct tb_nhi *nhi)
 	if (!nhi->ops->init_interrupts)
 		return dev_err_probe(dev, -EINVAL, "missing required NHI ops\n");
 
+	if (!nhi->ring_layout)
+		nhi->ring_layout = &nhi_default_ring_layout;
+
 	nhi->hop_count = ioread32(nhi->iobase + REG_CAPS) & 0x3ff;
 	dev_dbg(dev, "total paths: %d\n", nhi->hop_count);
 
diff --git a/drivers/thunderbolt/nhi.h b/drivers/thunderbolt/nhi.h
index 4884c3f5a2b2..035cee433a3c 100644
--- a/drivers/thunderbolt/nhi.h
+++ b/drivers/thunderbolt/nhi.h
@@ -40,6 +40,24 @@ void nhi_reset_interface(struct tb_nhi *nhi);
 
 extern const struct dev_pm_ops nhi_pm_ops;
 
+/**
+ * struct tb_nhi_ring_layout - Layout of the ring registers in the NHI MMIO space
+ * @tx_desc_base: Offset of the descriptor registers of the first TX ring
+ * @rx_desc_base: Offset of the descriptor registers of the first RX ring
+ * @desc_stride: Stride between the descriptor registers of neighboring rings
+ * @tx_options_base: Offset of the options registers of the first TX ring
+ * @rx_options_base: Offset of the options registers of the first RX ring
+ * @options_stride: Stride between the options registers of neighboring rings
+ */
+struct tb_nhi_ring_layout {
+	u32 tx_desc_base;
+	u32 rx_desc_base;
+	u32 desc_stride;
+	u32 tx_options_base;
+	u32 rx_options_base;
+	u32 options_stride;
+};
+
 /**
  * struct tb_nhi_ops - NHI specific optional operations
  * @init: NHI specific initialization
diff --git a/include/linux/thunderbolt.h b/include/linux/thunderbolt.h
index d48623fda79b..7c2717bd2945 100644
--- a/include/linux/thunderbolt.h
+++ b/include/linux/thunderbolt.h
@@ -503,6 +503,8 @@ void tb_service_properties_changed(struct tb_service *svc);
  *	  interrupt_work when dispatching interrupts to individual rings.
  * @dev: Device associated with this NHI instance
  * @ops: NHI specific optional ops
+ * @ring_layout: Layout of the ring registers inside @iobase. If not set
+ *		 the default layout from the USB4 specification is used.
  * @iobase: MMIO space of the NHI
  * @tx_rings: All Tx rings available on this host controller
  * @rx_rings: All Rx rings available on this host controller
@@ -524,6 +526,7 @@ struct tb_nhi {
 	spinlock_t lock;
 	struct device *dev;
 	const struct tb_nhi_ops *ops;
+	const struct tb_nhi_ring_layout *ring_layout;
 	void __iomem *iobase;
 	struct tb_ring **tx_rings;
 	struct tb_ring **rx_rings;

-- 
2.55.0