From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Wed, 5 Aug 2015 17:04:01 -0300
Subject: Initial import

---
 arch/metag/mm/l2cache.c | 192 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 192 insertions(+)
 create mode 100644 arch/metag/mm/l2cache.c

(limited to 'arch/metag/mm/l2cache.c')

diff --git a/arch/metag/mm/l2cache.c b/arch/metag/mm/l2cache.c
new file mode 100644
index 000000000..c64ee615c
--- /dev/null
+++ b/arch/metag/mm/l2cache.c
@@ -0,0 +1,192 @@
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/delay.h>
+
+#include <asm/l2cache.h>
+#include <asm/metag_isa.h>
+
+/* If non-0, then initialise the L2 cache */
+static int l2cache_init = 1;
+/* If non-0, then initialise the L2 cache prefetch */
+static int l2cache_init_pf = 1;
+
+int l2c_pfenable;
+
+static volatile u32 l2c_testdata[16] __initdata __aligned(64);
+
+static int __init parse_l2cache(char *p)
+{
+	char *cp = p;
+
+	if (get_option(&cp, &l2cache_init) != 1) {
+		pr_err("Bad l2cache parameter (%s)\n", p);
+		return 1;
+	}
+	return 0;
+}
+early_param("l2cache", parse_l2cache);
+
+static int __init parse_l2cache_pf(char *p)
+{
+	char *cp = p;
+
+	if (get_option(&cp, &l2cache_init_pf) != 1) {
+		pr_err("Bad l2cache_pf parameter (%s)\n", p);
+		return 1;
+	}
+	return 0;
+}
+early_param("l2cache_pf", parse_l2cache_pf);
+
+static int __init meta_l2c_setup(void)
+{
+	/*
+	 * If the L2 cache isn't even present, don't do anything, but say so in
+	 * the log.
+	 */
+	if (!meta_l2c_is_present()) {
+		pr_info("L2 Cache: Not present\n");
+		return 0;
+	}
+
+	/*
+	 * Check whether the line size is recognised.
+	 */
+	if (!meta_l2c_linesize()) {
+		pr_warn_once("L2 Cache: unknown line size id (config=0x%08x)\n",
+			     meta_l2c_config());
+	}
+
+	/*
+	 * Initialise state.
+	 */
+	l2c_pfenable = _meta_l2c_pf_is_enabled();
+
+	/*
+	 * Enable the L2 cache and print to log whether it was already enabled
+	 * by the bootloader.
+	 */
+	if (l2cache_init) {
+		pr_info("L2 Cache: Enabling... ");
+		if (meta_l2c_enable())
+			pr_cont("already enabled\n");
+		else
+			pr_cont("done\n");
+	} else {
+		pr_info("L2 Cache: Not enabling\n");
+	}
+
+	/*
+	 * Enable L2 cache prefetch.
+	 */
+	if (l2cache_init_pf) {
+		pr_info("L2 Cache: Enabling prefetch... ");
+		if (meta_l2c_pf_enable(1))
+			pr_cont("already enabled\n");
+		else
+			pr_cont("done\n");
+	} else {
+		pr_info("L2 Cache: Not enabling prefetch\n");
+	}
+
+	return 0;
+}
+core_initcall(meta_l2c_setup);
+
+int meta_l2c_disable(void)
+{
+	unsigned long flags;
+	int en;
+
+	if (!meta_l2c_is_present())
+		return 1;
+
+	/*
+	 * Prevent other threads writing during the writeback, otherwise the
+	 * writes will get "lost" when the L2 is disabled.
+	 */
+	__global_lock2(flags);
+	en = meta_l2c_is_enabled();
+	if (likely(en)) {
+		_meta_l2c_pf_enable(0);
+		wr_fence();
+		_meta_l2c_purge();
+		_meta_l2c_enable(0);
+	}
+	__global_unlock2(flags);
+
+	return !en;
+}
+
+int meta_l2c_enable(void)
+{
+	unsigned long flags;
+	int en;
+
+	if (!meta_l2c_is_present())
+		return 0;
+
+	/*
+	 * Init (clearing the L2) can happen while the L2 is disabled, so other
+	 * threads are safe to continue executing, however we must not init the
+	 * cache if it's already enabled (dirty lines would be discarded), so
+	 * this operation should still be atomic with other threads.
+	 */
+	__global_lock1(flags);
+	en = meta_l2c_is_enabled();
+	if (likely(!en)) {
+		_meta_l2c_init();
+		_meta_l2c_enable(1);
+		_meta_l2c_pf_enable(l2c_pfenable);
+	}
+	__global_unlock1(flags);
+
+	return en;
+}
+
+int meta_l2c_pf_enable(int pfenable)
+{
+	unsigned long flags;
+	int en = l2c_pfenable;
+
+	if (!meta_l2c_is_present())
+		return 0;
+
+	/*
+	 * We read modify write the enable register, so this operation must be
+	 * atomic with other threads.
+	 */
+	__global_lock1(flags);
+	en = l2c_pfenable;
+	l2c_pfenable = pfenable;
+	if (meta_l2c_is_enabled())
+		_meta_l2c_pf_enable(pfenable);
+	__global_unlock1(flags);
+
+	return en;
+}
+
+int meta_l2c_flush(void)
+{
+	unsigned long flags;
+	int en;
+
+	/*
+	 * Prevent other threads writing during the writeback. This also
+	 * involves read modify writes.
+	 */
+	__global_lock2(flags);
+	en = meta_l2c_is_enabled();
+	if (likely(en)) {
+		_meta_l2c_pf_enable(0);
+		wr_fence();
+		_meta_l2c_purge();
+		_meta_l2c_enable(0);
+		_meta_l2c_init();
+		_meta_l2c_enable(1);
+		_meta_l2c_pf_enable(l2c_pfenable);
+	}
+	__global_unlock2(flags);
+
+	return !en;
+}
-- 
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