ARM: mxs: Add clock support

Add clock for MXS-based SoCs, MX23 and MX28.
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

arch/arm/mach-mxs/clock.c

+/*
+ * Based on arch/arm/plat-omap/clock.c
+ *
+ * Copyright (C) 2004 - 2005 Nokia corporation
+ * Written by Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
+ * Modified for omap shared clock framework by Tony Lindgren <tony@atomide.com>
+ * Copyright 2007 Freescale Semiconductor, Inc. All Rights Reserved.
+ * Copyright 2008 Juergen Beisert, kernel@pengutronix.de
+ *
+ * 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.
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA  02110-1301, USA.
+ */
+
+/* #define DEBUG */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+#include <linux/proc_fs.h>
+#include <linux/semaphore.h>
+#include <linux/string.h>
+
+#include <mach/clock.h>
+
+static LIST_HEAD(clocks);
+static DEFINE_MUTEX(clocks_mutex);
+
+/*-------------------------------------------------------------------------
+ * Standard clock functions defined in include/linux/clk.h
+ *-------------------------------------------------------------------------*/
+
+static void __clk_disable(struct clk *clk)
+{
+	if (clk == NULL || IS_ERR(clk))
+		return;
+	WARN_ON(!clk->usecount);
+
+	if (!(--clk->usecount)) {
+		if (clk->disable)
+			clk->disable(clk);
+		__clk_disable(clk->parent);
+		__clk_disable(clk->secondary);
+	}
+}
+
+static int __clk_enable(struct clk *clk)
+{
+	if (clk == NULL || IS_ERR(clk))
+		return -EINVAL;
+
+	if (clk->usecount++ == 0) {
+		__clk_enable(clk->parent);
+		__clk_enable(clk->secondary);
+
+		if (clk->enable)
+			clk->enable(clk);
+	}
+	return 0;
+}
+
+/* This function increments the reference count on the clock and enables the
+ * clock if not already enabled. The parent clock tree is recursively enabled
+ */
+int clk_enable(struct clk *clk)
+{
+	int ret = 0;
+
+	if (clk == NULL || IS_ERR(clk))
+		return -EINVAL;
+
+	mutex_lock(&clocks_mutex);
+	ret = __clk_enable(clk);
+	mutex_unlock(&clocks_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL(clk_enable);
+
+/* This function decrements the reference count on the clock and disables
+ * the clock when reference count is 0. The parent clock tree is
+ * recursively disabled
+ */
+void clk_disable(struct clk *clk)
+{
+	if (clk == NULL || IS_ERR(clk))
+		return;
+
+	mutex_lock(&clocks_mutex);
+	__clk_disable(clk);
+	mutex_unlock(&clocks_mutex);
+}
+EXPORT_SYMBOL(clk_disable);
+
+/* Retrieve the *current* clock rate. If the clock itself
+ * does not provide a special calculation routine, ask
+ * its parent and so on, until one is able to return
+ * a valid clock rate
+ */
+unsigned long clk_get_rate(struct clk *clk)
+{
+	if (clk == NULL || IS_ERR(clk))
+		return 0UL;
+
+	if (clk->get_rate)
+		return clk->get_rate(clk);
+
+	return clk_get_rate(clk->parent);
+}
+EXPORT_SYMBOL(clk_get_rate);
+
+/* Round the requested clock rate to the nearest supported
+ * rate that is less than or equal to the requested rate.
+ * This is dependent on the clock's current parent.
+ */
+long clk_round_rate(struct clk *clk, unsigned long rate)
+{
+	if (clk == NULL || IS_ERR(clk) || !clk->round_rate)
+		return 0;
+
+	return clk->round_rate(clk, rate);
+}
+EXPORT_SYMBOL(clk_round_rate);
+
+/* Set the clock to the requested clock rate. The rate must
+ * match a supported rate exactly based on what clk_round_rate returns
+ */
+int clk_set_rate(struct clk *clk, unsigned long rate)
+{
+	int ret = -EINVAL;
+
+	if (clk == NULL || IS_ERR(clk) || clk->set_rate == NULL || rate == 0)
+		return ret;
+
+	mutex_lock(&clocks_mutex);
+	ret = clk->set_rate(clk, rate);
+	mutex_unlock(&clocks_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL(clk_set_rate);
+
+/* Set the clock's parent to another clock source */
+int clk_set_parent(struct clk *clk, struct clk *parent)
+{
+	int ret = -EINVAL;
+	struct clk *old;
+
+	if (clk == NULL || IS_ERR(clk) || parent == NULL ||
+	    IS_ERR(parent) || clk->set_parent == NULL)
+		return ret;
+
+	if (clk->usecount)
+		clk_enable(parent);
+
+	mutex_lock(&clocks_mutex);
+	ret = clk->set_parent(clk, parent);
+	if (ret == 0) {
+		old = clk->parent;
+		clk->parent = parent;
+	} else {
+		old = parent;
+	}
+	mutex_unlock(&clocks_mutex);
+
+	if (clk->usecount)
+		clk_disable(old);
+
+	return ret;
+}
+EXPORT_SYMBOL(clk_set_parent);
+
+/* Retrieve the clock's parent clock source */
+struct clk *clk_get_parent(struct clk *clk)
+{
+	struct clk *ret = NULL;
+
+	if (clk == NULL || IS_ERR(clk))
+		return ret;
+
+	return clk->parent;
+}
+EXPORT_SYMBOL(clk_get_parent);

arch/arm/mach-mxs/include/mach/clkdev.h

+#ifndef __MACH_MXS_CLKDEV_H__
+#define __MACH_MXS_CLKDEV_H__
+
+#define __clk_get(clk) ({ 1; })
+#define __clk_put(clk) do { } while (0)
+
+#endif

arch/arm/mach-mxs/include/mach/clock.h

+/*
+ * Copyright 2005-2007 Freescale Semiconductor, Inc. All Rights Reserved.
+ * Copyright 2008 Juergen Beisert, kernel@pengutronix.de
+ *
+ * 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.
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA  02110-1301, USA.
+ */
+
+#ifndef __MACH_MXS_CLOCK_H__
+#define __MACH_MXS_CLOCK_H__
+
+#ifndef __ASSEMBLY__
+#include <linux/list.h>
+
+struct module;
+
+struct clk {
+	int id;
+	/* Source clock this clk depends on */
+	struct clk *parent;
+	/* Secondary clock to enable/disable with this clock */
+	struct clk *secondary;
+	/* Reference count of clock enable/disable */
+	__s8 usecount;
+	/* Register bit position for clock's enable/disable control. */
+	u8 enable_shift;
+	/* Register address for clock's enable/disable control. */
+	void __iomem *enable_reg;
+	u32 flags;
+	/* get the current clock rate (always a fresh value) */
+	unsigned long (*get_rate) (struct clk *);
+	/* Function ptr to set the clock to a new rate. The rate must match a
+	   supported rate returned from round_rate. Leave blank if clock is not
+	   programmable */
+	int (*set_rate) (struct clk *, unsigned long);
+	/* Function ptr to round the requested clock rate to the nearest
+	   supported rate that is less than or equal to the requested rate. */
+	unsigned long (*round_rate) (struct clk *, unsigned long);
+	/* Function ptr to enable the clock. Leave blank if clock can not
+	   be gated. */
+	int (*enable) (struct clk *);
+	/* Function ptr to disable the clock. Leave blank if clock can not
+	   be gated. */
+	void (*disable) (struct clk *);
+	/* Function ptr to set the parent clock of the clock. */
+	int (*set_parent) (struct clk *, struct clk *);
+};
+
+int clk_register(struct clk *clk);
+void clk_unregister(struct clk *clk);
+
+#endif /* __ASSEMBLY__ */
+#endif /* __MACH_MXS_CLOCK_H__ */