sh: clkfwk: Wire up clk_get_sys() support.

This stubs in clk_get_sys() from the ARM clkdev implementation.
Tentatively conver the clk_get() lookup code to use this, and once the
rest of the in-tree users are happy with this, it can replace the
fallback lookups.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/include/asm/clock.h

@@ -37,6 +37,13 @@ struct clk {
 	unsigned long		arch_flags;
 };
 
+struct clk_lookup {
+	struct list_head	node;
+	const char		*dev_id;
+	const char		*con_id;
+	struct clk		*clk;
+};
+
 #define CLK_ENABLE_ON_INIT	(1 << 0)
 
 /* Should be defined by processor-specific code */

arch/sh/kernel/cpu/clock.c

@@ -10,6 +10,10 @@
  *
  *  Modified for omap shared clock framework by Tony Lindgren <tony@atomide.com>
  *
+ *  With clkdev bits:
+ *
+ *	Copyright (C) 2008 Russell King.
+ *
  * 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.
@@ -334,15 +338,70 @@ long clk_round_rate(struct clk *clk, unsigned long rate)
 }
 EXPORT_SYMBOL_GPL(clk_round_rate);
 
+/*
+ * Find the correct struct clk for the device and connection ID.
+ * We do slightly fuzzy matching here:
+ *  An entry with a NULL ID is assumed to be a wildcard.
+ *  If an entry has a device ID, it must match
+ *  If an entry has a connection ID, it must match
+ * Then we take the most specific entry - with the following
+ * order of precidence: dev+con > dev only > con only.
+ */
+static struct clk *clk_find(const char *dev_id, const char *con_id)
+{
+	struct clk_lookup *p;
+	struct clk *clk = NULL;
+	int match, best = 0;
+
+	list_for_each_entry(p, &clock_list, node) {
+		match = 0;
+		if (p->dev_id) {
+			if (!dev_id || strcmp(p->dev_id, dev_id))
+				continue;
+			match += 2;
+		}
+		if (p->con_id) {
+			if (!con_id || strcmp(p->con_id, con_id))
+				continue;
+			match += 1;
+		}
+		if (match == 0)
+			continue;
+
+		if (match > best) {
+			clk = p->clk;
+			best = match;
+		}
+	}
+	return clk;
+}
+
+struct clk *clk_get_sys(const char *dev_id, const char *con_id)
+{
+	struct clk *clk;
+
+	mutex_lock(&clock_list_sem);
+	clk = clk_find(dev_id, con_id);
+	mutex_unlock(&clock_list_sem);
+
+	return clk ? clk : ERR_PTR(-ENOENT);
+}
+EXPORT_SYMBOL_GPL(clk_get_sys);
+
 /*
  * Returns a clock. Note that we first try to use device id on the bus
  * and clock name. If this fails, we try to use clock name only.
  */
 struct clk *clk_get(struct device *dev, const char *id)
 {
+	const char *dev_id = dev ? dev_name(dev) : NULL;
 	struct clk *p, *clk = ERR_PTR(-ENOENT);
 	int idno;
 
+	clk = clk_get_sys(dev_id, id);
+	if (clk)
+		return clk;
+
 	if (dev == NULL || dev->bus != &platform_bus_type)
 		idno = -1;
 	else