metag: Cache/TLB handling

Add cache and TLB handling code for metag, including the required
callbacks used by MM switches and DMA operations. Caches can be
partitioned between the hardware threads and the global space, however
this is usually configured by the bootloader so Linux doesn't make any
changes to this configuration. TLBs aren't configurable, so only need
consideration to flush them.

On Meta1 the L1 cache was VIVT which required a full flush on MM switch.
Meta2 has a VIPT L1 cache so it doesn't require the full flush on MM
switch. Meta2 can also have a writeback L2 with hardware prefetch which
requires some special handling. Support is optional, and the L2 can be
detected and initialised by Linux.

Signed-off-by: James Hogan <james.hogan@imgtec.com>

1 files changed, 258 insertions, 0 deletions

diff --git a/arch/metag/include/asm/l2cache.h b/arch/metag/include/asm/l2cache.h
new file mode 100644
index 000000000000..bffbeaa4d93b
--- /dev/null
+++ b/arch/metag/include/asm/l2cache.h
@@ -0,0 +1,258 @@
+#ifndef _METAG_L2CACHE_H
+#define _METAG_L2CACHE_H
+
+#ifdef CONFIG_METAG_L2C
+
+#include <asm/global_lock.h>
+#include <asm/io.h>
+
+/*
+ * Store the last known value of pfenable (we don't want prefetch enabled while
+ * L2 is off).
+ */
+extern int l2c_pfenable;
+
+/* defined in arch/metag/drivers/core-sysfs.c */
+extern struct sysdev_class cache_sysclass;
+
+static inline void wr_fence(void);
+
+/*
+ * Functions for reading of L2 cache configuration.
+ */
+
+/* Get raw L2 config register (CORE_CONFIG3) */
+static inline unsigned int meta_l2c_config(void)
+{
+	const unsigned int *corecfg3 = (const unsigned int *)METAC_CORE_CONFIG3;
+	return *corecfg3;
+}
+
+/* Get whether the L2 is present */
+static inline int meta_l2c_is_present(void)
+{
+	return meta_l2c_config() & METAC_CORECFG3_L2C_HAVE_L2C_BIT;
+}
+
+/* Get whether the L2 is configured for write-back instead of write-through */
+static inline int meta_l2c_is_writeback(void)
+{
+	return meta_l2c_config() & METAC_CORECFG3_L2C_MODE_BIT;
+}
+
+/* Get whether the L2 is unified instead of separated code/data */
+static inline int meta_l2c_is_unified(void)
+{
+	return meta_l2c_config() & METAC_CORECFG3_L2C_UNIFIED_BIT;
+}
+
+/* Get the L2 cache size in bytes */
+static inline unsigned int meta_l2c_size(void)
+{
+	unsigned int size_s;
+	if (!meta_l2c_is_present())
+		return 0;
+	size_s = (meta_l2c_config() & METAC_CORECFG3_L2C_SIZE_BITS)
+			>> METAC_CORECFG3_L2C_SIZE_S;
+	/* L2CSIZE is in KiB */
+	return 1024 << size_s;
+}
+
+/* Get the number of ways in the L2 cache */
+static inline unsigned int meta_l2c_ways(void)
+{
+	unsigned int ways_s;
+	if (!meta_l2c_is_present())
+		return 0;
+	ways_s = (meta_l2c_config() & METAC_CORECFG3_L2C_NUM_WAYS_BITS)
+			>> METAC_CORECFG3_L2C_NUM_WAYS_S;
+	return 0x1 << ways_s;
+}
+
+/* Get the line size of the L2 cache */
+static inline unsigned int meta_l2c_linesize(void)
+{
+	unsigned int line_size;
+	if (!meta_l2c_is_present())
+		return 0;
+	line_size = (meta_l2c_config() & METAC_CORECFG3_L2C_LINE_SIZE_BITS)
+			>> METAC_CORECFG3_L2C_LINE_SIZE_S;
+	switch (line_size) {
+	case METAC_CORECFG3_L2C_LINE_SIZE_64B:
+		return 64;
+	default:
+		return 0;
+	}
+}
+
+/* Get the revision ID of the L2 cache */
+static inline unsigned int meta_l2c_revision(void)
+{
+	return (meta_l2c_config() & METAC_CORECFG3_L2C_REV_ID_BITS)
+			>> METAC_CORECFG3_L2C_REV_ID_S;
+}
+
+
+/*
+ * Start an initialisation of the L2 cachelines and wait for completion.
+ * This should only be done in a LOCK1 or LOCK2 critical section while the L2
+ * is disabled.
+ */
+static inline void _meta_l2c_init(void)
+{
+	metag_out32(SYSC_L2C_INIT_INIT, SYSC_L2C_INIT);
+	while (metag_in32(SYSC_L2C_INIT) == SYSC_L2C_INIT_IN_PROGRESS)
+		/* do nothing */;
+}
+
+/*
+ * Start a writeback of dirty L2 cachelines and wait for completion.
+ * This should only be done in a LOCK1 or LOCK2 critical section.
+ */
+static inline void _meta_l2c_purge(void)
+{
+	metag_out32(SYSC_L2C_PURGE_PURGE, SYSC_L2C_PURGE);
+	while (metag_in32(SYSC_L2C_PURGE) == SYSC_L2C_PURGE_IN_PROGRESS)
+		/* do nothing */;
+}
+
+/* Set whether the L2 cache is enabled. */
+static inline void _meta_l2c_enable(int enabled)
+{
+	unsigned int enable;
+
+	enable = metag_in32(SYSC_L2C_ENABLE);
+	if (enabled)
+		enable |= SYSC_L2C_ENABLE_ENABLE_BIT;
+	else
+		enable &= ~SYSC_L2C_ENABLE_ENABLE_BIT;
+	metag_out32(enable, SYSC_L2C_ENABLE);
+}
+
+/* Set whether the L2 cache prefetch is enabled. */
+static inline void _meta_l2c_pf_enable(int pfenabled)
+{
+	unsigned int enable;
+
+	enable = metag_in32(SYSC_L2C_ENABLE);
+	if (pfenabled)
+		enable |= SYSC_L2C_ENABLE_PFENABLE_BIT;
+	else
+		enable &= ~SYSC_L2C_ENABLE_PFENABLE_BIT;
+	metag_out32(enable, SYSC_L2C_ENABLE);
+}
+
+/* Return whether the L2 cache is enabled */
+static inline int _meta_l2c_is_enabled(void)
+{
+	return metag_in32(SYSC_L2C_ENABLE) & SYSC_L2C_ENABLE_ENABLE_BIT;
+}
+
+/* Return whether the L2 cache prefetch is enabled */
+static inline int _meta_l2c_pf_is_enabled(void)
+{
+	return metag_in32(SYSC_L2C_ENABLE) & SYSC_L2C_ENABLE_PFENABLE_BIT;
+}
+
+
+/* Return whether the L2 cache is enabled */
+static inline int meta_l2c_is_enabled(void)
+{
+	int en;
+
+	/*
+	 * There is no need to lock at the moment, as the enable bit is never
+	 * intermediately changed, so we will never see an intermediate result.
+	 */
+	en = _meta_l2c_is_enabled();
+
+	return en;
+}
+
+/*
+ * Ensure the L2 cache is disabled.
+ * Return whether the L2 was previously disabled.
+ */
+int meta_l2c_disable(void);
+
+/*
+ * Ensure the L2 cache is enabled.
+ * Return whether the L2 was previously enabled.
+ */
+int meta_l2c_enable(void);
+
+/* Return whether the L2 cache prefetch is enabled */
+static inline int meta_l2c_pf_is_enabled(void)
+{
+	return l2c_pfenable;
+}
+
+/*
+ * Set whether the L2 cache prefetch is enabled.
+ * Return whether the L2 prefetch was previously enabled.
+ */
+int meta_l2c_pf_enable(int pfenable);
+
+/*
+ * Flush the L2 cache.
+ * Return 1 if the L2 is disabled.
+ */
+int meta_l2c_flush(void);
+
+/*
+ * Write back all dirty cache lines in the L2 cache.
+ * Return 1 if the L2 is disabled or there isn't any writeback.
+ */
+static inline int meta_l2c_writeback(void)
+{
+	unsigned long flags;
+	int en;
+
+	/* no need to purge if it's not a writeback cache */
+	if (!meta_l2c_is_writeback())
+		return 1;
+
+	/*
+	 * Purge only works if the L2 is enabled, and involves reading back to
+	 * detect completion, so keep this operation atomic with other threads.
+	 */
+	__global_lock1(flags);
+	en = meta_l2c_is_enabled();
+	if (likely(en)) {
+		wr_fence();
+		_meta_l2c_purge();
+	}
+	__global_unlock1(flags);
+
+	return !en;
+}
+
+#else /* CONFIG_METAG_L2C */
+
+#define meta_l2c_config()		0
+#define meta_l2c_is_present()		0
+#define meta_l2c_is_writeback()		0
+#define meta_l2c_is_unified()		0
+#define meta_l2c_size()			0
+#define meta_l2c_ways()			0
+#define meta_l2c_linesize()		0
+#define meta_l2c_revision()		0
+
+#define meta_l2c_is_enabled()		0
+#define _meta_l2c_pf_is_enabled()	0
+#define meta_l2c_pf_is_enabled()	0
+#define meta_l2c_disable()		1
+#define meta_l2c_enable()		0
+#define meta_l2c_pf_enable(X)		0
+static inline int meta_l2c_flush(void)
+{
+	return 1;
+}
+static inline int meta_l2c_writeback(void)
+{
+	return 1;
+}
+
+#endif /* CONFIG_METAG_L2C */
+
+#endif /* _METAG_L2CACHE_H */