powerpc/vas: Move VAS API to book3s common platform

The pseries platform will share vas and nx code and interfaces
with the PowerNV platform, so create the
arch/powerpc/platforms/book3s/ directory and move VAS API code
there. Functionality is not changed.

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/e05c8db17b9eabe3545b902d034238e4c6c08180.camel@linux.ibm.com

3 files changed, 295 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/book3s/Kconfig b/arch/powerpc/platforms/book3s/Kconfig
new file mode 100644
index 000000000000..34c931592ef0
--- /dev/null
+++ b/arch/powerpc/platforms/book3s/Kconfig
@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: GPL-2.0
+config PPC_VAS
+	bool "IBM Virtual Accelerator Switchboard (VAS)"
+	depends on (PPC_POWERNV || PPC_PSERIES) && PPC_64K_PAGES
+	default y
+	help
+	  This enables support for IBM Virtual Accelerator Switchboard (VAS).
+
+	  VAS devices are found in POWER9-based and later systems, they
+	  provide access to accelerator coprocessors such as NX-GZIP and
+	  NX-842. This config allows the kernel to use NX-842 accelerators,
+	  and user-mode APIs for the NX-GZIP accelerator on POWER9 PowerNV
+	  and POWER10 PowerVM platforms.
+
+	  If unsure, say "N".
diff --git a/arch/powerpc/platforms/book3s/Makefile b/arch/powerpc/platforms/book3s/Makefile
new file mode 100644
index 000000000000..e790f1910f61
--- /dev/null
+++ b/arch/powerpc/platforms/book3s/Makefile
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_PPC_VAS)	+= vas-api.o
diff --git a/arch/powerpc/platforms/book3s/vas-api.c b/arch/powerpc/platforms/book3s/vas-api.c
new file mode 100644
index 000000000000..cfc9d7dd65ab
--- /dev/null
+++ b/arch/powerpc/platforms/book3s/vas-api.c
@@ -0,0 +1,278 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * VAS user space API for its accelerators (Only NX-GZIP is supported now)
+ * Copyright (C) 2019 Haren Myneni, IBM Corp
+ */
+
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/cdev.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/io.h>
+#include <asm/vas.h>
+#include <uapi/asm/vas-api.h>
+
+/*
+ * The driver creates the device node that can be used as follows:
+ * For NX-GZIP
+ *
+ *	fd = open("/dev/crypto/nx-gzip", O_RDWR);
+ *	rc = ioctl(fd, VAS_TX_WIN_OPEN, &attr);
+ *	paste_addr = mmap(NULL, PAGE_SIZE, prot, MAP_SHARED, fd, 0ULL).
+ *	vas_copy(&crb, 0, 1);
+ *	vas_paste(paste_addr, 0, 1);
+ *	close(fd) or exit process to close window.
+ *
+ * where "vas_copy" and "vas_paste" are defined in copy-paste.h.
+ * copy/paste returns to the user space directly. So refer NX hardware
+ * documententation for exact copy/paste usage and completion / error
+ * conditions.
+ */
+
+/*
+ * Wrapper object for the nx-gzip device - there is just one instance of
+ * this node for the whole system.
+ */
+static struct coproc_dev {
+	struct cdev cdev;
+	struct device *device;
+	char *name;
+	dev_t devt;
+	struct class *class;
+	enum vas_cop_type cop_type;
+} coproc_device;
+
+struct coproc_instance {
+	struct coproc_dev *coproc;
+	struct vas_window *txwin;
+};
+
+static char *coproc_devnode(struct device *dev, umode_t *mode)
+{
+	return kasprintf(GFP_KERNEL, "crypto/%s", dev_name(dev));
+}
+
+static int coproc_open(struct inode *inode, struct file *fp)
+{
+	struct coproc_instance *cp_inst;
+
+	cp_inst = kzalloc(sizeof(*cp_inst), GFP_KERNEL);
+	if (!cp_inst)
+		return -ENOMEM;
+
+	cp_inst->coproc = container_of(inode->i_cdev, struct coproc_dev,
+					cdev);
+	fp->private_data = cp_inst;
+
+	return 0;
+}
+
+static int coproc_ioc_tx_win_open(struct file *fp, unsigned long arg)
+{
+	void __user *uptr = (void __user *)arg;
+	struct vas_tx_win_attr txattr = {};
+	struct vas_tx_win_open_attr uattr;
+	struct coproc_instance *cp_inst;
+	struct vas_window *txwin;
+	int rc, vasid;
+
+	cp_inst = fp->private_data;
+
+	/*
+	 * One window for file descriptor
+	 */
+	if (cp_inst->txwin)
+		return -EEXIST;
+
+	rc = copy_from_user(&uattr, uptr, sizeof(uattr));
+	if (rc) {
+		pr_err("%s(): copy_from_user() returns %d\n", __func__, rc);
+		return -EFAULT;
+	}
+
+	if (uattr.version != 1) {
+		pr_err("Invalid version\n");
+		return -EINVAL;
+	}
+
+	vasid = uattr.vas_id;
+
+	vas_init_tx_win_attr(&txattr, cp_inst->coproc->cop_type);
+
+	txattr.lpid = mfspr(SPRN_LPID);
+	txattr.pidr = mfspr(SPRN_PID);
+	txattr.user_win = true;
+	txattr.rsvd_txbuf_count = false;
+	txattr.pswid = false;
+
+	pr_devel("Pid %d: Opening txwin, PIDR %ld\n", txattr.pidr,
+				mfspr(SPRN_PID));
+
+	txwin = vas_tx_win_open(vasid, cp_inst->coproc->cop_type, &txattr);
+	if (IS_ERR(txwin)) {
+		pr_err("%s() vas_tx_win_open() failed, %ld\n", __func__,
+					PTR_ERR(txwin));
+		return PTR_ERR(txwin);
+	}
+
+	cp_inst->txwin = txwin;
+
+	return 0;
+}
+
+static int coproc_release(struct inode *inode, struct file *fp)
+{
+	struct coproc_instance *cp_inst = fp->private_data;
+
+	if (cp_inst->txwin) {
+		vas_win_close(cp_inst->txwin);
+		cp_inst->txwin = NULL;
+	}
+
+	kfree(cp_inst);
+	fp->private_data = NULL;
+
+	/*
+	 * We don't know here if user has other receive windows
+	 * open, so we can't really call clear_thread_tidr().
+	 * So, once the process calls set_thread_tidr(), the
+	 * TIDR value sticks around until process exits, resulting
+	 * in an extra copy in restore_sprs().
+	 */
+
+	return 0;
+}
+
+static int coproc_mmap(struct file *fp, struct vm_area_struct *vma)
+{
+	struct coproc_instance *cp_inst = fp->private_data;
+	struct vas_window *txwin;
+	unsigned long pfn;
+	u64 paste_addr;
+	pgprot_t prot;
+	int rc;
+
+	txwin = cp_inst->txwin;
+
+	if ((vma->vm_end - vma->vm_start) > PAGE_SIZE) {
+		pr_debug("%s(): size 0x%zx, PAGE_SIZE 0x%zx\n", __func__,
+				(vma->vm_end - vma->vm_start), PAGE_SIZE);
+		return -EINVAL;
+	}
+
+	/* Ensure instance has an open send window */
+	if (!txwin) {
+		pr_err("%s(): No send window open?\n", __func__);
+		return -EINVAL;
+	}
+
+	vas_win_paste_addr(txwin, &paste_addr, NULL);
+	pfn = paste_addr >> PAGE_SHIFT;
+
+	/* flags, page_prot from cxl_mmap(), except we want cachable */
+	vma->vm_flags |= VM_IO | VM_PFNMAP;
+	vma->vm_page_prot = pgprot_cached(vma->vm_page_prot);
+
+	prot = __pgprot(pgprot_val(vma->vm_page_prot) | _PAGE_DIRTY);
+
+	rc = remap_pfn_range(vma, vma->vm_start, pfn + vma->vm_pgoff,
+			vma->vm_end - vma->vm_start, prot);
+
+	pr_devel("%s(): paste addr %llx at %lx, rc %d\n", __func__,
+			paste_addr, vma->vm_start, rc);
+
+	return rc;
+}
+
+static long coproc_ioctl(struct file *fp, unsigned int cmd, unsigned long arg)
+{
+	switch (cmd) {
+	case VAS_TX_WIN_OPEN:
+		return coproc_ioc_tx_win_open(fp, arg);
+	default:
+		return -EINVAL;
+	}
+}
+
+static struct file_operations coproc_fops = {
+	.open = coproc_open,
+	.release = coproc_release,
+	.mmap = coproc_mmap,
+	.unlocked_ioctl = coproc_ioctl,
+};
+
+/*
+ * Supporting only nx-gzip coprocessor type now, but this API code
+ * extended to other coprocessor types later.
+ */
+int vas_register_coproc_api(struct module *mod, enum vas_cop_type cop_type,
+				const char *name)
+{
+	int rc = -EINVAL;
+	dev_t devno;
+
+	rc = alloc_chrdev_region(&coproc_device.devt, 1, 1, name);
+	if (rc) {
+		pr_err("Unable to allocate coproc major number: %i\n", rc);
+		return rc;
+	}
+
+	pr_devel("%s device allocated, dev [%i,%i]\n", name,
+			MAJOR(coproc_device.devt), MINOR(coproc_device.devt));
+
+	coproc_device.class = class_create(mod, name);
+	if (IS_ERR(coproc_device.class)) {
+		rc = PTR_ERR(coproc_device.class);
+		pr_err("Unable to create %s class %d\n", name, rc);
+		goto err_class;
+	}
+	coproc_device.class->devnode = coproc_devnode;
+	coproc_device.cop_type = cop_type;
+
+	coproc_fops.owner = mod;
+	cdev_init(&coproc_device.cdev, &coproc_fops);
+
+	devno = MKDEV(MAJOR(coproc_device.devt), 0);
+	rc = cdev_add(&coproc_device.cdev, devno, 1);
+	if (rc) {
+		pr_err("cdev_add() failed %d\n", rc);
+		goto err_cdev;
+	}
+
+	coproc_device.device = device_create(coproc_device.class, NULL,
+			devno, NULL, name, MINOR(devno));
+	if (IS_ERR(coproc_device.device)) {
+		rc = PTR_ERR(coproc_device.device);
+		pr_err("Unable to create coproc-%d %d\n", MINOR(devno), rc);
+		goto err;
+	}
+
+	pr_devel("%s: Added dev [%d,%d]\n", __func__, MAJOR(devno),
+			MINOR(devno));
+
+	return 0;
+
+err:
+	cdev_del(&coproc_device.cdev);
+err_cdev:
+	class_destroy(coproc_device.class);
+err_class:
+	unregister_chrdev_region(coproc_device.devt, 1);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(vas_register_coproc_api);
+
+void vas_unregister_coproc_api(void)
+{
+	dev_t devno;
+
+	cdev_del(&coproc_device.cdev);
+	devno = MKDEV(MAJOR(coproc_device.devt), 0);
+	device_destroy(coproc_device.class, devno);
+
+	class_destroy(coproc_device.class);
+	unregister_chrdev_region(coproc_device.devt, 1);
+}
+EXPORT_SYMBOL_GPL(vas_unregister_coproc_api);