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MXC family: Add clock handling
Internal clock path handling for the mxc CPUs. Changed against the original Freescale code (and against clocklib for example): - clock rate is always calculated whenever one ask for the current rate (means struct clk has no more a member called "rate"). So switching the PLL base frequency will propagate immediately to all other clocks that are depending on this frequency. Signed-off-by: Juergen Beisert <j.beisert@pengutronix.de>
This commit is contained in:
Juergen Beisert
Robert Schwebel
parent
38a41fdf94
commit
c0db2ea4e3
@ -3,4 +3,4 @@
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#
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# Common support
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obj-y := irq.o
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obj-y := irq.o clock.o
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331
arch/arm/plat-mxc/clock.c
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331
arch/arm/plat-mxc/clock.c
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@ -0,0 +1,331 @@
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/*
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* Based on arch/arm/plat-omap/clock.c
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*
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* Copyright (C) 2004 - 2005 Nokia corporation
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* Written by Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
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* Modified for omap shared clock framework by Tony Lindgren <tony@atomide.com>
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* Copyright 2007 Freescale Semiconductor, Inc. All Rights Reserved.
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* Copyright 2008 Juergen Beisert, kernel@pengutronix.de
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301, USA.
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*/
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/* #define DEBUG */
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#include <linux/clk.h>
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#include <linux/err.h>
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#include <linux/errno.h>
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#include <linux/init.h>
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#include <linux/io.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/platform_device.h>
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#include <linux/proc_fs.h>
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#include <linux/semaphore.h>
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#include <linux/string.h>
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#include <linux/version.h>
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#include <asm/arch/clock.h>
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static LIST_HEAD(clocks);
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static DEFINE_MUTEX(clocks_mutex);
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/*-------------------------------------------------------------------------
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* Standard clock functions defined in include/linux/clk.h
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*-------------------------------------------------------------------------*/
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/*
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* Retrieve a clock by name.
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*
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* Note that we first try to use device id on the bus
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* and clock name. If this fails, we try to use "<name>.<id>". If this fails,
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* we try to use clock name only.
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* The reference count to the clock's module owner ref count is incremented.
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*/
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struct clk *clk_get(struct device *dev, const char *id)
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{
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struct clk *p, *clk = ERR_PTR(-ENOENT);
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int idno;
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const char *str;
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if (id == NULL)
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return clk;
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if (dev == NULL || dev->bus != &platform_bus_type)
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idno = -1;
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else
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idno = to_platform_device(dev)->id;
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mutex_lock(&clocks_mutex);
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list_for_each_entry(p, &clocks, node) {
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if (p->id == idno &&
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strcmp(id, p->name) == 0 && try_module_get(p->owner)) {
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clk = p;
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goto found;
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}
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}
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str = strrchr(id, '.');
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if (str) {
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int cnt = str - id;
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str++;
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idno = simple_strtol(str, NULL, 10);
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list_for_each_entry(p, &clocks, node) {
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if (p->id == idno &&
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strlen(p->name) == cnt &&
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strncmp(id, p->name, cnt) == 0 &&
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try_module_get(p->owner)) {
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clk = p;
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goto found;
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}
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}
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}
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list_for_each_entry(p, &clocks, node) {
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if (strcmp(id, p->name) == 0 && try_module_get(p->owner)) {
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clk = p;
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goto found;
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}
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}
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printk(KERN_WARNING "clk: Unable to get requested clock: %s\n", id);
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found:
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mutex_unlock(&clocks_mutex);
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return clk;
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}
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EXPORT_SYMBOL(clk_get);
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static void __clk_disable(struct clk *clk)
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{
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if (clk == NULL || IS_ERR(clk))
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return;
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__clk_disable(clk->parent);
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__clk_disable(clk->secondary);
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if (!(--clk->usecount) && clk->disable)
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clk->disable(clk);
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}
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static int __clk_enable(struct clk *clk)
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{
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if (clk == NULL || IS_ERR(clk))
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return -EINVAL;
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__clk_enable(clk->parent);
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__clk_enable(clk->secondary);
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if (clk->usecount++ == 0 && clk->enable)
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clk->enable(clk);
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return 0;
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}
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/* This function increments the reference count on the clock and enables the
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* clock if not already enabled. The parent clock tree is recursively enabled
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*/
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int clk_enable(struct clk *clk)
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{
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int ret = 0;
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if (clk == NULL || IS_ERR(clk))
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return -EINVAL;
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mutex_lock(&clocks_mutex);
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ret = __clk_enable(clk);
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mutex_unlock(&clocks_mutex);
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return ret;
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}
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EXPORT_SYMBOL(clk_enable);
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/* This function decrements the reference count on the clock and disables
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* the clock when reference count is 0. The parent clock tree is
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* recursively disabled
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*/
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void clk_disable(struct clk *clk)
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{
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if (clk == NULL || IS_ERR(clk))
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return;
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mutex_lock(&clocks_mutex);
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__clk_disable(clk);
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mutex_unlock(&clocks_mutex);
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}
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EXPORT_SYMBOL(clk_disable);
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/* Retrieve the *current* clock rate. If the clock itself
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* does not provide a special calculation routine, ask
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* its parent and so on, until one is able to return
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* a valid clock rate
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*/
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unsigned long clk_get_rate(struct clk *clk)
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{
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if (clk == NULL || IS_ERR(clk))
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return 0UL;
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if (clk->get_rate)
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return clk->get_rate(clk);
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return clk_get_rate(clk->parent);
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}
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EXPORT_SYMBOL(clk_get_rate);
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/* Decrement the clock's module reference count */
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void clk_put(struct clk *clk)
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{
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if (clk && !IS_ERR(clk))
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module_put(clk->owner);
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}
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EXPORT_SYMBOL(clk_put);
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/* Round the requested clock rate to the nearest supported
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* rate that is less than or equal to the requested rate.
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* This is dependent on the clock's current parent.
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*/
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long clk_round_rate(struct clk *clk, unsigned long rate)
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{
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if (clk == NULL || IS_ERR(clk) || !clk->round_rate)
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return 0;
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return clk->round_rate(clk, rate);
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}
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EXPORT_SYMBOL(clk_round_rate);
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/* Set the clock to the requested clock rate. The rate must
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* match a supported rate exactly based on what clk_round_rate returns
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*/
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int clk_set_rate(struct clk *clk, unsigned long rate)
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{
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int ret = -EINVAL;
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if (clk == NULL || IS_ERR(clk) || clk->set_rate == NULL || rate == 0)
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return ret;
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mutex_lock(&clocks_mutex);
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ret = clk->set_rate(clk, rate);
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mutex_unlock(&clocks_mutex);
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return ret;
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}
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EXPORT_SYMBOL(clk_set_rate);
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/* Set the clock's parent to another clock source */
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int clk_set_parent(struct clk *clk, struct clk *parent)
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{
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int ret = -EINVAL;
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if (clk == NULL || IS_ERR(clk) || parent == NULL ||
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IS_ERR(parent) || clk->set_parent == NULL)
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return ret;
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mutex_lock(&clocks_mutex);
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ret = clk->set_parent(clk, parent);
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if (ret == 0)
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clk->parent = parent;
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mutex_unlock(&clocks_mutex);
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return ret;
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}
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EXPORT_SYMBOL(clk_set_parent);
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/* Retrieve the clock's parent clock source */
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struct clk *clk_get_parent(struct clk *clk)
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{
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struct clk *ret = NULL;
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if (clk == NULL || IS_ERR(clk))
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return ret;
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return clk->parent;
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}
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EXPORT_SYMBOL(clk_get_parent);
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/*
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* Add a new clock to the clock tree.
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*/
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int clk_register(struct clk *clk)
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{
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if (clk == NULL || IS_ERR(clk))
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return -EINVAL;
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mutex_lock(&clocks_mutex);
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list_add(&clk->node, &clocks);
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mutex_unlock(&clocks_mutex);
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return 0;
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}
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EXPORT_SYMBOL(clk_register);
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/* Remove a clock from the clock tree */
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void clk_unregister(struct clk *clk)
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{
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if (clk == NULL || IS_ERR(clk))
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return;
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mutex_lock(&clocks_mutex);
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list_del(&clk->node);
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mutex_unlock(&clocks_mutex);
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}
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EXPORT_SYMBOL(clk_unregister);
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#ifdef CONFIG_PROC_FS
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static int mxc_clock_read_proc(char *page, char **start, off_t off,
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int count, int *eof, void *data)
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{
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struct clk *clkp;
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char *p = page;
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int len;
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list_for_each_entry(clkp, &clocks, node) {
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p += sprintf(p, "%s-%d:\t\t%lu, %d", clkp->name, clkp->id,
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clk_get_rate(clkp), clkp->usecount);
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if (clkp->parent)
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p += sprintf(p, ", %s-%d\n", clkp->parent->name,
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clkp->parent->id);
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else
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p += sprintf(p, "\n");
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}
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len = (p - page) - off;
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if (len < 0)
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len = 0;
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*eof = (len <= count) ? 1 : 0;
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*start = page + off;
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return len;
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}
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static int __init mxc_setup_proc_entry(void)
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{
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struct proc_dir_entry *res;
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res = create_proc_read_entry("cpu/clocks", 0, NULL,
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mxc_clock_read_proc, NULL);
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if (!res) {
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printk(KERN_ERR "Failed to create proc/cpu/clocks\n");
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return -ENOMEM;
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}
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return 0;
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}
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late_initcall(mxc_setup_proc_entry);
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#endif
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67
include/asm-arm/arch-mxc/clock.h
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67
include/asm-arm/arch-mxc/clock.h
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@ -0,0 +1,67 @@
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/*
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* Copyright 2005-2007 Freescale Semiconductor, Inc. All Rights Reserved.
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* Copyright 2008 Juergen Beisert, kernel@pengutronix.de
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301, USA.
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*/
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#ifndef __ASM_ARCH_MXC_CLOCK_H__
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#define __ASM_ARCH_MXC_CLOCK_H__
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#ifndef __ASSEMBLY__
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#include <linux/list.h>
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struct module;
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struct clk {
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struct list_head node;
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struct module *owner;
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const char *name;
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int id;
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/* Source clock this clk depends on */
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struct clk *parent;
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/* Secondary clock to enable/disable with this clock */
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struct clk *secondary;
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/* Reference count of clock enable/disable */
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__s8 usecount;
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/* Register bit position for clock's enable/disable control. */
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u8 enable_shift;
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/* Register address for clock's enable/disable control. */
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u32 enable_reg;
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u32 flags;
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/* get the current clock rate (always a fresh value) */
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unsigned long (*get_rate) (struct clk *);
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/* Function ptr to set the clock to a new rate. The rate must match a
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supported rate returned from round_rate. Leave blank if clock is not
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programmable */
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int (*set_rate) (struct clk *, unsigned long);
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/* Function ptr to round the requested clock rate to the nearest
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supported rate that is less than or equal to the requested rate. */
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unsigned long (*round_rate) (struct clk *, unsigned long);
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/* Function ptr to enable the clock. Leave blank if clock can not
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be gated. */
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int (*enable) (struct clk *);
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/* Function ptr to disable the clock. Leave blank if clock can not
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be gated. */
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void (*disable) (struct clk *);
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/* Function ptr to set the parent clock of the clock. */
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int (*set_parent) (struct clk *, struct clk *);
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};
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int clk_register(struct clk *clk);
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void clk_unregister(struct clk *clk);
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#endif /* __ASSEMBLY__ */
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#endif /* __ASM_ARCH_MXC_CLOCK_H__ */
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