tilegx: provide kernel support for the tilegx UART shim

The TILE-Gx chip includes an on-chip UART.  This change adds support
for using the UART from within the kernel.  The UART shim has more
functionality than is exposed here, but to keep the kernel code and
binary simpler, this is a subset of the full API designed to enable
a standard Linux tty serial driver only.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

1 files changed, 105 insertions, 0 deletions

diff --git a/arch/tile/include/gxio/uart.h b/arch/tile/include/gxio/uart.h
new file mode 100644
index 000000000000..438ee7e46c7b
--- /dev/null
+++ b/arch/tile/include/gxio/uart.h
@@ -0,0 +1,105 @@
+/*
+ * Copyright 2013 Tilera Corporation. All Rights Reserved.
+ *
+ *   This program is free software; you can redistribute it and/or
+ *   modify it under the terms of the GNU General Public License
+ *   as published by the Free Software Foundation, version 2.
+ *
+ *   This program is distributed in the hope that it will be useful, but
+ *   WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ *   NON INFRINGEMENT.  See the GNU General Public License for
+ *   more details.
+ */
+
+#ifndef _GXIO_UART_H_
+#define _GXIO_UART_H_
+
+#include "common.h"
+
+#include <hv/drv_uart_intf.h>
+#include <hv/iorpc.h>
+
+/*
+ *
+ * An API for manipulating UART interface.
+ */
+
+/*
+ *
+ * The Rshim allows access to the processor's UART interface.
+ */
+
+/* A context object used to manage UART resources. */
+typedef struct {
+
+	/* File descriptor for calling up to the hypervisor. */
+	int fd;
+
+	/* The VA at which our MMIO registers are mapped. */
+	char *mmio_base;
+
+} gxio_uart_context_t;
+
+/* Request UART interrupts.
+ *
+ *  Request that interrupts be delivered to a tile when the UART's
+ *  Receive FIFO is written, or the Write FIFO is read.
+ *
+ * @param context Pointer to a properly initialized gxio_uart_context_t.
+ * @param bind_cpu_x X coordinate of CPU to which interrupt will be delivered.
+ * @param bind_cpu_y Y coordinate of CPU to which interrupt will be delivered.
+ * @param bind_interrupt IPI interrupt number.
+ * @param bind_event Sub-interrupt event bit number; a negative value can
+ *  disable the interrupt.
+ * @return Zero if all of the requested UART events were successfully
+ *  configured to interrupt.
+ */
+extern int gxio_uart_cfg_interrupt(gxio_uart_context_t *context,
+				   int bind_cpu_x,
+				   int bind_cpu_y,
+				   int bind_interrupt, int bind_event);
+
+/* Initialize a UART context.
+ *
+ *  A properly initialized context must be obtained before any of the other
+ *  gxio_uart routines may be used.
+ *
+ * @param context Pointer to a gxio_uart_context_t, which will be initialized
+ *  by this routine, if it succeeds.
+ * @param uart_index Index of the UART to use.
+ * @return Zero if the context was successfully initialized, else a
+ *  GXIO_ERR_xxx error code.
+ */
+extern int gxio_uart_init(gxio_uart_context_t *context, int uart_index);
+
+/* Destroy a UART context.
+ *
+ *  Once destroyed, a context may not be used with any gxio_uart routines
+ *  other than gxio_uart_init().  After this routine returns, no further
+ *  interrupts requested on this context will be delivered.  The state and
+ *  configuration of the pins which had been attached to this context are
+ *  unchanged by this operation.
+ *
+ * @param context Pointer to a gxio_uart_context_t.
+ * @return Zero if the context was successfully destroyed, else a
+ *  GXIO_ERR_xxx error code.
+ */
+extern int gxio_uart_destroy(gxio_uart_context_t *context);
+
+/* Write UART register.
+ * @param context Pointer to a gxio_uart_context_t.
+ * @param offset UART register offset.
+ * @param word Data will be wrote to UART reigister.
+ */
+extern void gxio_uart_write(gxio_uart_context_t *context, uint64_t offset,
+			    uint64_t word);
+
+/* Read UART register.
+ * @param context Pointer to a gxio_uart_context_t.
+ * @param offset UART register offset.
+ * @return Data read from UART register.
+ */
+extern uint64_t gxio_uart_read(gxio_uart_context_t *context, uint64_t offset);
+
+#endif /* _GXIO_UART_H_ */