patch-2.3.9 linux/arch/mips/sni/io.c

• Lines: 230
• Date: Fri Jun 25 17:40:13 1999
• Orig file: v2.3.8/linux/arch/mips/sni/io.c
• Orig date: Tue Oct 20 13:52:55 1998

diff -u --recursive --new-file v2.3.8/linux/arch/mips/sni/io.c linux/arch/mips/sni/io.c
@@ -1,11 +1,10 @@
-/*
+/* $Id: io.c,v 1.3 1999/01/04 16:03:58 ralf Exp $
+ *
  * This file is subject to the terms and conditions of the GNU General Public
  * License.  See the file "COPYING" in the main directory of this archive
  * for more details.
  *
  * Low level I/O functions for SNI.
- *
- * $Id: io.c,v 1.2 1998/03/27 08:53:50 ralf Exp $
  */
 #include <linux/string.h>
 #include <asm/mipsconfig.h>
@@ -14,46 +13,42 @@
 #include <asm/spinlock.h>
 #include <asm/sni.h>
 
-unsigned char sni_map_isa_cache;
-
-#define unused __attribute__((unused))
-
-/*
- * The PCIMT_CSMAPISA is shared by all processors; we need locking.
- *
- * XXX It's legal to use all the I/O memory access functions in interrupt
- * code, so we need to use the _irq locking stuff which may result in
- * significant IRQ latencies.
- */
-static spinlock_t csmapisa_lock unused = SPIN_LOCK_UNLOCKED;
-
 /*
  * Urgs...  We only can see a 16mb window of the 4gb EISA address space
  * at PCIMT_EISA_BASE.  Maladia segmentitis ...
  *
- * XXX Check out if accessing PCIMT_CSMAPISA really is slow.
- * For now assume so.
+ * To avoid locking and all the related headacke we implement this such
+ * that accessing the bus address space nests, so we're treating this
+ * correctly even for interrupts.  This is going to suck seriously for
+ * the SMP members of the RM family.
+ *
+ * Making things worse the PCIMT_CSMAPISA register resides on the X bus with
+ * it's unbeatable 1.4 mb/s transfer rate.
  */
-static inline void update_isa_cache(unsigned long address)
+
+static inline void eisa_map(unsigned long address)
 {
 	unsigned char upper;
 
 	upper = address >> 24;
-	if (sni_map_isa_cache != upper) {
-		sni_map_isa_cache = upper;
-		*(volatile unsigned char *)PCIMT_CSMAPISA = ~upper;
-	}
+	*(volatile unsigned char *)PCIMT_CSMAPISA = ~upper;
 }
 
+#define save_eisa_map()							\
+	(*(volatile unsigned char *)PCIMT_CSMAPISA)
+#define restore_eisa_map(val)						\
+	do { (*(volatile unsigned char *)PCIMT_CSMAPISA) = val; } while(0)
+
 static unsigned char sni_readb(unsigned long addr)
 {
 	unsigned char res;
+	unsigned int save_map;
 
-	spin_lock_irq(&csmapisa_lock);
-	update_isa_cache(addr);
+	save_map = save_eisa_map();
+	eisa_map(addr);
 	addr &= 0xffffff;
 	res = *(volatile unsigned char *) (PCIMT_EISA_BASE + addr);
-	spin_unlock_irq(&csmapisa_lock);
+	restore_eisa_map(save_map);
 
 	return res;
 }
@@ -61,12 +56,13 @@
 static unsigned short sni_readw(unsigned long addr)
 {
 	unsigned short res;
+	unsigned int save_map;
 
-	spin_lock_irq(&csmapisa_lock);
-	update_isa_cache(addr);
+	save_map = save_eisa_map();
+	eisa_map(addr);
 	addr &= 0xffffff;
 	res = *(volatile unsigned char *) (PCIMT_EISA_BASE + addr);
-	spin_unlock_irq(&csmapisa_lock);
+	restore_eisa_map(save_map);
 
 	return res;
 }
@@ -74,101 +70,111 @@
 static unsigned int sni_readl(unsigned long addr)
 {
 	unsigned int res;
+	unsigned int save_map;
 
-	spin_lock_irq(&csmapisa_lock);
-	update_isa_cache(addr);
+	save_map = save_eisa_map();
+	eisa_map(addr);
 	addr &= 0xffffff;
 	res = *(volatile unsigned char *) (PCIMT_EISA_BASE + addr);
-	spin_unlock_irq(&csmapisa_lock);
+	restore_eisa_map(save_map);
 
 	return res;
 }
 
 static void sni_writeb(unsigned char val, unsigned long addr)
 {
-	spin_lock_irq(&csmapisa_lock);
-	update_isa_cache(addr);
+	unsigned int save_map;
+
+	save_map = save_eisa_map();
+	eisa_map(addr);
 	addr &= 0xffffff;
 	*(volatile unsigned char *) (PCIMT_EISA_BASE + addr) = val;
-	spin_unlock_irq(&csmapisa_lock);
+	restore_eisa_map(save_map);
 }
 
 static void sni_writew(unsigned short val, unsigned long addr)
 {
-	spin_lock_irq(&csmapisa_lock);
-	update_isa_cache(addr);
+	unsigned int save_map;
+
+	save_map = save_eisa_map();
+	eisa_map(addr);
 	addr &= 0xffffff;
 	*(volatile unsigned char *) (PCIMT_EISA_BASE + addr) = val;
-	spin_unlock_irq(&csmapisa_lock);
+	restore_eisa_map(save_map);
 }
 
 static void sni_writel(unsigned int val, unsigned long addr)
 {
-	spin_lock_irq(&csmapisa_lock);
-	update_isa_cache(addr);
+	unsigned int save_map;
+
+	save_map = save_eisa_map();
+	eisa_map(addr);
 	addr &= 0xffffff;
 	*(volatile unsigned char *) (PCIMT_EISA_BASE + addr) = val;
-	spin_unlock_irq(&csmapisa_lock);
+	restore_eisa_map(save_map);
 }
 
 static void sni_memset_io(unsigned long addr, int val, unsigned long len)
 {
 	unsigned long waddr;
+	unsigned int save_map;
 
+	save_map = save_eisa_map();
 	waddr = PCIMT_EISA_BASE | (addr & 0xffffff);
-	spin_lock_irq(&csmapisa_lock);
 	while(len) {
 		unsigned long fraglen;
 
 		fraglen = (~addr + 1) & 0xffffff;
 		fraglen = (fraglen < len) ? fraglen : len;
-		update_isa_cache(addr);
+		eisa_map(addr);
 		memset((char *)waddr, val, fraglen);
 		addr += fraglen;
 		waddr = waddr + fraglen - 0x1000000;
 		len -= fraglen;
 	}
-	spin_unlock_irq(&csmapisa_lock);
+	restore_eisa_map(save_map);
 }
 
 static void sni_memcpy_fromio(unsigned long to, unsigned long from, unsigned long len)
 {
 	unsigned long waddr;
+	unsigned int save_map;
 
+	save_map = save_eisa_map();
 	waddr = PCIMT_EISA_BASE | (from & 0xffffff);
-	spin_lock_irq(&csmapisa_lock);
 	while(len) {
 		unsigned long fraglen;
 
 		fraglen = (~from + 1) & 0xffffff;
 		fraglen = (fraglen < len) ? fraglen : len;
-		update_isa_cache(from);
+		eisa_map(from);
 		memcpy((void *)to, (void *)waddr, fraglen);
 		to += fraglen;
 		from += fraglen;
 		waddr = waddr + fraglen - 0x1000000;
 		len -= fraglen;
 	}
-	spin_unlock_irq(&csmapisa_lock);
+	restore_eisa_map(save_map);
 }
 
 static void sni_memcpy_toio(unsigned long to, unsigned long from, unsigned long len)
 {
 	unsigned long waddr;
+	unsigned int save_map;
 
+	save_map = save_eisa_map();
 	waddr = PCIMT_EISA_BASE | (to & 0xffffff);
-	spin_lock_irq(&csmapisa_lock);
 	while(len) {
 		unsigned long fraglen;
 
 		fraglen = (~to + 1) & 0xffffff;
 		fraglen = (fraglen < len) ? fraglen : len;
-		update_isa_cache(to);
+		eisa_map(to);
 		memcpy((char *)to + PCIMT_EISA_BASE, (void *)from, fraglen);
 		to += fraglen;
 		from += fraglen;
 		waddr = waddr + fraglen - 0x1000000;
 		len -= fraglen;
 	}
-	spin_unlock_irq(&csmapisa_lock);
+	restore_eisa_map(save_map);
 }