powerpc/powernv/vas: Define vas_tx_win_open()

Define an interface to open a VAS send window. This interface is
intended to be used the Nest Accelerator (NX) driver(s) to open
a send window and use it to submit compression/encryption requests
to a VAS receive window.

The receive window, identified by the [vasid, cop] parameters, must
already be open in VAS (i.e connected to an NX engine).
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/vas.h

@@ -80,6 +80,29 @@ struct vas_rx_win_attr {
 	int tc_mode;
 };
 
+/*
+ * Window attributes specified by the in-kernel owner of a send window.
+ */
+struct vas_tx_win_attr {
+	enum vas_cop_type cop;
+	int wcreds_max;
+	int lpid;
+	int pidr;		/* hardware PID (from SPRN_PID) */
+	int pid;		/* linux process id */
+	int pswid;
+	int rsvd_txbuf_count;
+	int tc_mode;
+
+	bool user_win;
+	bool pin_win;
+	bool rej_no_credit;
+	bool rsvd_txbuf_enable;
+	bool tx_wcred_mode;
+	bool rx_wcred_mode;
+	bool tx_win_ord_mode;
+	bool rx_win_ord_mode;
+};
+
 /*
  * Helper to initialize receive window attributes to defaults for an
  * NX window.
@@ -95,6 +118,25 @@ void vas_init_rx_win_attr(struct vas_rx_win_attr *rxattr, enum vas_cop_type cop)
 struct vas_window *vas_rx_win_open(int vasid, enum vas_cop_type cop,
 				   struct vas_rx_win_attr *attr);
 
+/*
+ * Helper to initialize send window attributes to defaults for an NX window.
+ */
+extern void vas_init_tx_win_attr(struct vas_tx_win_attr *txattr,
+			enum vas_cop_type cop);
+
+/*
+ * Open a VAS send window for the instance of VAS identified by @vasid
+ * and the co-processor type @cop. Use @attr to initialize attributes
+ * of the window.
+ *
+ * Note: The instance of VAS must already have an open receive window for
+ * the coprocessor type @cop.
+ *
+ * Return a handle to the send window or ERR_PTR() on error.
+ */
+struct vas_window *vas_tx_win_open(int vasid, enum vas_cop_type cop,
+			struct vas_tx_win_attr *attr);
+
 /*
  * Close the send or receive window identified by @win. For receive windows
  * return -EAGAIN if there are active send windows attached to this receive

arch/powerpc/platforms/powernv/vas-window.c

@@ -64,7 +64,7 @@ static inline void get_uwc_mmio_bar(struct vas_window *window,
  * space. Unlike MMIO regions (map_mmio_region() below), paste region must
  * be mapped cache-able and is only applicable to send windows.
  */
-void *map_paste_region(struct vas_window *txwin)
+static void *map_paste_region(struct vas_window *txwin)
 {
 	int len;
 	void *map;
@@ -100,7 +100,6 @@ void *map_paste_region(struct vas_window *txwin)
 	return ERR_PTR(-ENOMEM);
 }
 
-
 static void *map_mmio_region(char *name, u64 start, int len)
 {
 	void *map;
@@ -574,7 +573,7 @@ static void put_rx_win(struct vas_window *rxwin)
  *
  * See also function header of set_vinst_win().
  */
-struct vas_window *get_vinst_rxwin(struct vas_instance *vinst,
+static struct vas_window *get_vinst_rxwin(struct vas_instance *vinst,
 			enum vas_cop_type cop, u32 pswid)
 {
 	struct vas_window *rxwin;
@@ -847,6 +846,157 @@ struct vas_window *vas_rx_win_open(int vasid, enum vas_cop_type cop,
 }
 EXPORT_SYMBOL_GPL(vas_rx_win_open);
 
+void vas_init_tx_win_attr(struct vas_tx_win_attr *txattr, enum vas_cop_type cop)
+{
+	memset(txattr, 0, sizeof(*txattr));
+
+	if (cop == VAS_COP_TYPE_842 || cop == VAS_COP_TYPE_842_HIPRI) {
+		txattr->rej_no_credit = false;
+		txattr->rx_wcred_mode = true;
+		txattr->tx_wcred_mode = true;
+		txattr->rx_win_ord_mode = true;
+		txattr->tx_win_ord_mode = true;
+	} else if (cop == VAS_COP_TYPE_FTW) {
+		txattr->user_win = true;
+	}
+}
+EXPORT_SYMBOL_GPL(vas_init_tx_win_attr);
+
+static void init_winctx_for_txwin(struct vas_window *txwin,
+			struct vas_tx_win_attr *txattr,
+			struct vas_winctx *winctx)
+{
+	/*
+	 * We first zero all fields and only set non-zero ones. Following
+	 * are some fields set to 0/false for the stated reason:
+	 *
+	 *	->notify_os_intr_reg	In powernv, send intrs to HV
+	 *	->rsvd_txbuf_count	Not supported yet.
+	 *	->notify_disable	False for NX windows
+	 *	->xtra_write		False for NX windows
+	 *	->notify_early		NA for NX windows
+	 *	->lnotify_lpid		NA for Tx windows
+	 *	->lnotify_pid		NA for Tx windows
+	 *	->lnotify_tid		NA for Tx windows
+	 *	->tx_win_cred_mode	Ignore for now for NX windows
+	 *	->rx_win_cred_mode	Ignore for now for NX windows
+	 */
+	memset(winctx, 0, sizeof(struct vas_winctx));
+
+	winctx->wcreds_max = txattr->wcreds_max ?: VAS_WCREDS_DEFAULT;
+
+	winctx->user_win = txattr->user_win;
+	winctx->nx_win = txwin->rxwin->nx_win;
+	winctx->pin_win = txattr->pin_win;
+
+	winctx->rx_wcred_mode = txattr->rx_wcred_mode;
+	winctx->tx_wcred_mode = txattr->tx_wcred_mode;
+	winctx->rx_word_mode = txattr->rx_win_ord_mode;
+	winctx->tx_word_mode = txattr->tx_win_ord_mode;
+
+	if (winctx->nx_win) {
+		winctx->data_stamp = true;
+		winctx->intr_disable = true;
+	}
+
+	winctx->lpid = txattr->lpid;
+	winctx->pidr = txattr->pidr;
+	winctx->rx_win_id = txwin->rxwin->winid;
+
+	winctx->dma_type = VAS_DMA_TYPE_INJECT;
+	winctx->tc_mode = txattr->tc_mode;
+	winctx->min_scope = VAS_SCOPE_LOCAL;
+	winctx->max_scope = VAS_SCOPE_VECTORED_GROUP;
+
+	winctx->pswid = 0;
+}
+
+static bool tx_win_args_valid(enum vas_cop_type cop,
+			struct vas_tx_win_attr *attr)
+{
+	if (attr->tc_mode != VAS_THRESH_DISABLED)
+		return false;
+
+	if (cop > VAS_COP_TYPE_MAX)
+		return false;
+
+	if (attr->user_win &&
+			(cop != VAS_COP_TYPE_FTW || attr->rsvd_txbuf_count))
+		return false;
+
+	return true;
+}
+
+struct vas_window *vas_tx_win_open(int vasid, enum vas_cop_type cop,
+			struct vas_tx_win_attr *attr)
+{
+	int rc;
+	struct vas_window *txwin;
+	struct vas_window *rxwin;
+	struct vas_winctx winctx;
+	struct vas_instance *vinst;
+
+	if (!tx_win_args_valid(cop, attr))
+		return ERR_PTR(-EINVAL);
+
+	vinst = find_vas_instance(vasid);
+	if (!vinst) {
+		pr_devel("vasid %d not found!\n", vasid);
+		return ERR_PTR(-EINVAL);
+	}
+
+	rxwin = get_vinst_rxwin(vinst, cop, attr->pswid);
+	if (IS_ERR(rxwin)) {
+		pr_devel("No RxWin for vasid %d, cop %d\n", vasid, cop);
+		return rxwin;
+	}
+
+	txwin = vas_window_alloc(vinst);
+	if (IS_ERR(txwin)) {
+		rc = PTR_ERR(txwin);
+		goto put_rxwin;
+	}
+
+	txwin->tx_win = 1;
+	txwin->rxwin = rxwin;
+	txwin->nx_win = txwin->rxwin->nx_win;
+	txwin->pid = attr->pid;
+	txwin->user_win = attr->user_win;
+
+	init_winctx_for_txwin(txwin, attr, &winctx);
+
+	init_winctx_regs(txwin, &winctx);
+
+	/*
+	 * If its a kernel send window, map the window address into the
+	 * kernel's address space. For user windows, user must issue an
+	 * mmap() to map the window into their address space.
+	 *
+	 * NOTE: If kernel ever resubmits a user CRB after handling a page
+	 *	 fault, we will need to map this into kernel as well.
+	 */
+	if (!txwin->user_win) {
+		txwin->paste_kaddr = map_paste_region(txwin);
+		if (IS_ERR(txwin->paste_kaddr)) {
+			rc = PTR_ERR(txwin->paste_kaddr);
+			goto free_window;
+		}
+	}
+
+	set_vinst_win(vinst, txwin);
+
+	return txwin;
+
+free_window:
+	vas_window_free(txwin);
+
+put_rxwin:
+	put_rx_win(rxwin);
+	return ERR_PTR(rc);
+
+}
+EXPORT_SYMBOL_GPL(vas_tx_win_open);
+
 static void poll_window_busy_state(struct vas_window *window)
 {
 	int busy;