[MIPS] Basic SPRAM support

Signed-off-by: Chris Dearman <chris@mips.com>
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 221 insertions, 0 deletions

diff --git a/arch/mips/kernel/spram.c b/arch/mips/kernel/spram.c
new file mode 100644
index 00000000000..6ddb507a87e
--- /dev/null
+++ b/arch/mips/kernel/spram.c
@@ -0,0 +1,221 @@
+/*
+ * MIPS SPRAM support
+ *
+ * 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; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * Copyright (C) 2007, 2008 MIPS Technologies, Inc.
+ */
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/ptrace.h>
+#include <linux/stddef.h>
+
+#include <asm/cpu.h>
+#include <asm/fpu.h>
+#include <asm/mipsregs.h>
+#include <asm/system.h>
+#include <asm/r4kcache.h>
+#include <asm/hazards.h>
+
+/*
+ * These definitions are correct for the 24K/34K/74K SPRAM sample
+ * implementation. The 4KS interpreted the tags differently...
+ */
+#define SPRAM_TAG0_ENABLE	0x00000080
+#define SPRAM_TAG0_PA_MASK	0xfffff000
+#define SPRAM_TAG1_SIZE_MASK	0xfffff000
+
+#define SPRAM_TAG_STRIDE	8
+
+#define ERRCTL_SPRAM		(1 << 28)
+
+/* errctl access */
+#define read_c0_errctl(x) read_c0_ecc(x)
+#define write_c0_errctl(x) write_c0_ecc(x)
+
+/*
+ * Different semantics to the set_c0_* function built by __BUILD_SET_C0
+ */
+static __cpuinit unsigned int bis_c0_errctl(unsigned int set)
+{
+	unsigned int res;
+	res = read_c0_errctl();
+	write_c0_errctl(res | set);
+	return res;
+}
+
+static __cpuinit void ispram_store_tag(unsigned int offset, unsigned int data)
+{
+	unsigned int errctl;
+
+	/* enable SPRAM tag access */
+	errctl = bis_c0_errctl(ERRCTL_SPRAM);
+	ehb();
+
+	write_c0_taglo(data);
+	ehb();
+
+	cache_op(Index_Store_Tag_I, CKSEG0|offset);
+	ehb();
+
+	write_c0_errctl(errctl);
+	ehb();
+}
+
+
+static __cpuinit unsigned int ispram_load_tag(unsigned int offset)
+{
+	unsigned int data;
+	unsigned int errctl;
+
+	/* enable SPRAM tag access */
+	errctl = bis_c0_errctl(ERRCTL_SPRAM);
+	ehb();
+	cache_op(Index_Load_Tag_I, CKSEG0 | offset);
+	ehb();
+	data = read_c0_taglo();
+	ehb();
+	write_c0_errctl(errctl);
+	ehb();
+
+	return data;
+}
+
+static __cpuinit void dspram_store_tag(unsigned int offset, unsigned int data)
+{
+	unsigned int errctl;
+
+	/* enable SPRAM tag access */
+	errctl = bis_c0_errctl(ERRCTL_SPRAM);
+	ehb();
+	write_c0_dtaglo(data);
+	ehb();
+	cache_op(Index_Store_Tag_D, CKSEG0 | offset);
+	ehb();
+	write_c0_errctl(errctl);
+	ehb();
+}
+
+
+static __cpuinit unsigned int dspram_load_tag(unsigned int offset)
+{
+	unsigned int data;
+	unsigned int errctl;
+
+	errctl = bis_c0_errctl(ERRCTL_SPRAM);
+	ehb();
+	cache_op(Index_Load_Tag_D, CKSEG0 | offset);
+	ehb();
+	data = read_c0_dtaglo();
+	ehb();
+	write_c0_errctl(errctl);
+	ehb();
+
+	return data;
+}
+
+static __cpuinit void probe_spram(char *type,
+	    unsigned int base,
+	    unsigned int (*read)(unsigned int),
+	    void (*write)(unsigned int, unsigned int))
+{
+	unsigned int firstsize = 0, lastsize = 0;
+	unsigned int firstpa = 0, lastpa = 0, pa = 0;
+	unsigned int offset = 0;
+	unsigned int size, tag0, tag1;
+	unsigned int enabled;
+	int i;
+
+	/*
+	 * The limit is arbitrary but avoids the loop running away if
+	 * the SPRAM tags are implemented differently
+	 */
+
+	for (i = 0; i < 8; i++) {
+		tag0 = read(offset);
+		tag1 = read(offset+SPRAM_TAG_STRIDE);
+		pr_debug("DBG %s%d: tag0=%08x tag1=%08x\n",
+			 type, i, tag0, tag1);
+
+		size = tag1 & SPRAM_TAG1_SIZE_MASK;
+
+		if (size == 0)
+			break;
+
+		if (i != 0) {
+			/* tags may repeat... */
+			if ((pa == firstpa && size == firstsize) ||
+			    (pa == lastpa && size == lastsize))
+				break;
+		}
+
+		/* Align base with size */
+		base = (base + size - 1) & ~(size-1);
+
+		/* reprogram the base address base address and enable */
+		tag0 = (base & SPRAM_TAG0_PA_MASK) | SPRAM_TAG0_ENABLE;
+		write(offset, tag0);
+
+		base += size;
+
+		/* reread the tag */
+		tag0 = read(offset);
+		pa = tag0 & SPRAM_TAG0_PA_MASK;
+		enabled = tag0 & SPRAM_TAG0_ENABLE;
+
+		if (i == 0) {
+			firstpa = pa;
+			firstsize = size;
+		}
+
+		lastpa = pa;
+		lastsize = size;
+
+		if (strcmp(type, "DSPRAM") == 0) {
+			unsigned int *vp = (unsigned int *)(CKSEG1 | pa);
+			unsigned int v;
+#define TDAT	0x5a5aa5a5
+			vp[0] = TDAT;
+			vp[1] = ~TDAT;
+
+			mb();
+
+			v = vp[0];
+			if (v != TDAT)
+				printk(KERN_ERR "vp=%p wrote=%08x got=%08x\n",
+				       vp, TDAT, v);
+			v = vp[1];
+			if (v != ~TDAT)
+				printk(KERN_ERR "vp=%p wrote=%08x got=%08x\n",
+				       vp+1, ~TDAT, v);
+		}
+
+		pr_info("%s%d: PA=%08x,Size=%08x%s\n",
+			type, i, pa, size, enabled ? ",enabled" : "");
+		offset += 2 * SPRAM_TAG_STRIDE;
+	}
+}
+
+__cpuinit void spram_config(void)
+{
+	struct cpuinfo_mips *c = &current_cpu_data;
+	unsigned int config0;
+
+	switch (c->cputype) {
+	case CPU_24K:
+	case CPU_34K:
+	case CPU_74K:
+		config0 = read_c0_config();
+		/* FIXME: addresses are Malta specific */
+		if (config0 & (1<<24)) {
+			probe_spram("ISPRAM", 0x1c000000,
+				    &ispram_load_tag, &ispram_store_tag);
+		}
+		if (config0 & (1<<23))
+			probe_spram("DSPRAM", 0x1c100000,
+				    &dspram_load_tag, &dspram_store_tag);
+	}
+}