[ARM] Ensure transmitter starts before leaving ssp_write_word()

Wait for BSY bit to be asserted before returning from
ssp_write_word().  This ensures that ssp_flush() will wait for
the transmitter to empty before returning.

Add ssp.h header.

arch/arm/mach-sa1100/ssp.c

@@ -39,7 +39,8 @@ static void ssp_interrupt(int irq, void *dev_id, struct pt_regs *regs)
  * @data: 16-bit, MSB justified data to write.
  *
  * Wait for a free entry in the SSP transmit FIFO, and write a data
- * word to the SSP port.
+ * word to the SSP port.  Wait for the SSP port to start sending
+ * the data.
  *
  * The caller is expected to perform the necessary locking.
  *
@@ -54,6 +55,9 @@ int ssp_write_word(u16 data)
 
 	Ser4SSDR = data;
 
+	while (!(Ser4SSSR & SSSR_BSY))
+		cpu_relax();
+
 	return 0;
 }
 

include/asm-arm/hardware/ssp.h

+/*
+ *  ssp.h
+ *
+ *  Copyright (C) 2003 Russell King, 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 version 2 as
+ * published by the Free Software Foundation.
+ */
+#ifndef SSP_H
+#define SSP_H
+
+struct ssp_state {
+	unsigned int	cr0;
+	unsigned int	cr1;
+};
+
+int ssp_write_word(u16 data);
+int ssp_read_word(void);
+void ssp_flush(void);
+void ssp_enable(void);
+void ssp_disable(void);
+void ssp_save_state(struct ssp_state *ssp);
+void ssp_restore_state(struct ssp_state *ssp);
+int ssp_init(void);
+void ssp_exit(void);
+
+#endif