[PATCH RFC 10/13] dmaengine: sdxi: Add PCI driver support

[Nathan Lynch via B4 Relay <devnull+nathan.lynch.amd.com@kernel.org>]

From: Nathan Lynch <nathan.lynch@amd.com>

Add support for binding to PCIe-hosted SDXI devices. SDXI requires
MSI(-X) for PCI implementations, so this code will be gated by
CONFIG_PCI_MSI in the Makefile.

Co-developed-by: Wei Huang <wei.huang2@amd.com>
Signed-off-by: Wei Huang <wei.huang2@amd.com>
Signed-off-by: Nathan Lynch <nathan.lynch@amd.com>
---
 drivers/dma/sdxi/pci.c | 216 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 216 insertions(+)

diff --git a/drivers/dma/sdxi/pci.c b/drivers/dma/sdxi/pci.c
new file mode 100644
index 0000000000000000000000000000000000000000..b7f74555395c605c4affffb198ee359accac8521
--- /dev/null
+++ b/drivers/dma/sdxi/pci.c
@@ -0,0 +1,216 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * SDXI PCI device code
+ *
+ * Copyright (C) 2025 Advanced Micro Devices, Inc.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/dev_printk.h>
+#include <linux/dma-direction.h>
+#include <linux/dma-mapping.h>
+#include <linux/errno.h>
+#include <linux/io.h>
+#include <linux/iomap.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/pci-ats.h>
+#include <linux/pci.h>
+
+#include "mmio.h"
+#include "sdxi.h"
+
+/*
+ * SDXI devices signal message 0 on error conditions, see "Error
+ * Logging Control and Status Registers".
+ */
+#define ERROR_IRQ_MSG 0
+
+/* MMIO BARs */
+#define MMIO_CTL_REGS_BAR		0x0
+#define MMIO_DOORBELL_BAR		0x2
+
+static struct pci_dev *sdxi_to_pci_dev(const struct sdxi_dev *sdxi)
+{
+	return to_pci_dev(sdxi_to_dev(sdxi));
+}
+
+static int sdxi_pci_irq_init(struct sdxi_dev *sdxi)
+{
+	struct pci_dev *pdev = sdxi_to_pci_dev(sdxi);
+	int msi_count;
+	int ret;
+
+	/* 1st irq for error + 1 for each context */
+	msi_count = sdxi->max_cxts + 1;
+
+	ret = pci_alloc_irq_vectors(pdev, 1, msi_count,
+				    PCI_IRQ_MSI | PCI_IRQ_MSIX);
+	if (ret < 0) {
+		sdxi_err(sdxi, "alloc MSI/MSI-X vectors failed\n");
+		return ret;
+	}
+
+	sdxi->error_irq = pci_irq_vector(pdev, ERROR_IRQ_MSG);
+
+	sdxi_dbg(sdxi, "allocated %d irq vectors", ret);
+
+	return 0;
+}
+
+static void sdxi_pci_irq_exit(struct sdxi_dev *sdxi)
+{
+	pci_free_irq_vectors(sdxi_to_pci_dev(sdxi));
+}
+
+static int sdxi_pci_map(struct sdxi_dev *sdxi)
+{
+	struct pci_dev *pdev = sdxi_to_pci_dev(sdxi);
+	int bars, ret;
+
+	bars = 1 << MMIO_CTL_REGS_BAR | 1 << MMIO_DOORBELL_BAR;
+	ret = pcim_iomap_regions(pdev, bars, SDXI_DRV_NAME);
+	if (ret) {
+		sdxi_err(sdxi, "pcim_iomap_regions failed (%d)\n", ret);
+		return ret;
+	}
+
+	sdxi->dbs_bar = pci_resource_start(pdev, MMIO_DOORBELL_BAR);
+
+	/* FIXME: pcim_iomap_table may return NULL, and it's deprecated. */
+	sdxi->ctrl_regs = pcim_iomap_table(pdev)[MMIO_CTL_REGS_BAR];
+	sdxi->dbs = pcim_iomap_table(pdev)[MMIO_DOORBELL_BAR];
+	if (!sdxi->ctrl_regs || !sdxi->dbs) {
+		sdxi_err(sdxi, "pcim_iomap_table failed\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void sdxi_pci_unmap(struct sdxi_dev *sdxi)
+{
+	struct pci_dev *pdev = sdxi_to_pci_dev(sdxi);
+
+	pcim_iounmap(pdev, sdxi->ctrl_regs);
+	pcim_iounmap(pdev, sdxi->dbs);
+}
+
+static int sdxi_pci_init(struct sdxi_dev *sdxi)
+{
+	struct pci_dev *pdev = sdxi_to_pci_dev(sdxi);
+	struct device *dev = &pdev->dev;
+	int dma_bits = 64;
+	int ret;
+
+	ret = pcim_enable_device(pdev);
+	if (ret) {
+		sdxi_err(sdxi, "pcim_enbale_device failed\n");
+		return ret;
+	}
+
+	pci_set_master(pdev);
+	ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(dma_bits));
+	if (ret) {
+		sdxi_err(sdxi, "failed to set DMA mask & coherent bits\n");
+		return ret;
+	}
+
+	ret = sdxi_pci_map(sdxi);
+	if (ret) {
+		sdxi_err(sdxi, "failed to map device IO resources\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static void sdxi_pci_exit(struct sdxi_dev *sdxi)
+{
+	sdxi_pci_unmap(sdxi);
+}
+
+static struct sdxi_dev *sdxi_device_alloc(struct device *dev)
+{
+	struct sdxi_dev *sdxi;
+
+	sdxi = kzalloc(sizeof(*sdxi), GFP_KERNEL);
+	if (!sdxi)
+		return NULL;
+
+	sdxi->dev = dev;
+
+	mutex_init(&sdxi->cxt_lock);
+
+	return sdxi;
+}
+
+static void sdxi_device_free(struct sdxi_dev *sdxi)
+{
+	kfree(sdxi);
+}
+
+static const struct sdxi_dev_ops sdxi_pci_dev_ops = {
+	.irq_init = sdxi_pci_irq_init,
+	.irq_exit = sdxi_pci_irq_exit,
+};
+
+static int sdxi_pci_probe(struct pci_dev *pdev,
+			  const struct pci_device_id *id)
+{
+	struct device *dev = &pdev->dev;
+	struct sdxi_dev *sdxi;
+	int err;
+
+	sdxi = sdxi_device_alloc(dev);
+	if (!sdxi)
+		return -ENOMEM;
+
+	pci_set_drvdata(pdev, sdxi);
+
+	err = sdxi_pci_init(sdxi);
+	if (err)
+		goto free_sdxi;
+
+	err = sdxi_device_init(sdxi, &sdxi_pci_dev_ops);
+	if (err)
+		goto pci_exit;
+
+	return 0;
+
+pci_exit:
+	sdxi_pci_exit(sdxi);
+free_sdxi:
+	sdxi_device_free(sdxi);
+
+	return err;
+}
+
+static void sdxi_pci_remove(struct pci_dev *pdev)
+{
+	struct sdxi_dev *sdxi = pci_get_drvdata(pdev);
+
+	sdxi_device_exit(sdxi);
+	sdxi_pci_exit(sdxi);
+	sdxi_device_free(sdxi);
+}
+
+static const struct pci_device_id sdxi_id_table[] = {
+	{ PCI_DEVICE_CLASS(PCI_CLASS_ACCELERATOR_SDXI, 0xffffff) },
+	{0, }
+};
+MODULE_DEVICE_TABLE(pci, sdxi_id_table);
+
+static struct pci_driver sdxi_driver = {
+	.name = "sdxi",
+	.id_table = sdxi_id_table,
+	.probe = sdxi_pci_probe,
+	.remove = sdxi_pci_remove,
+	.sriov_configure = pci_sriov_configure_simple,
+};
+
+module_pci_driver(sdxi_driver);

-- 
2.39.5